WorldWideScience

Sample records for heliospheric modeling system

  1. SEP modeling based on global heliospheric models at the CCMC

    Science.gov (United States)

    Mays, M. L.; Luhmann, J. G.; Odstrcil, D.; Bain, H. M.; Schwadron, N.; Gorby, M.; Li, Y.; Lee, K.; Zeitlin, C.; Jian, L. K.; Lee, C. O.; Mewaldt, R. A.; Galvin, A. B.

    2017-12-01

    Heliospheric models provide contextual information of conditions in the heliosphere, including the background solar wind conditions and shock structures, and are used as input to SEP models, providing an essential tool for understanding SEP properties. The global 3D MHD WSA-ENLIL+Cone model provides a time-dependent background heliospheric description, into which a spherical shaped hydrodynamic CME can be inserted. ENLIL simulates solar wind parameters and additionally one can extract the magnetic topologies of observer-connected magnetic field lines and all plasma and shock properties along those field lines. An accurate representation of the background solar wind is necessary for simulating transients. ENLIL simulations also drive SEP models such as the Solar Energetic Particle Model (SEPMOD) (Luhmann et al. 2007, 2010) and the Energetic Particle Radiation Environment Module (EPREM) (Schwadron et al. 2010). The Community Coordinated Modeling Center (CCMC) is in the process of making these SEP models available to the community and offering a system to run SEP models driven by a variety of heliospheric models available at CCMC. SEPMOD injects protons onto a sequence of observer field lines at intensities dependent on the connected shock source strength which are then integrated at the observer to approximate the proton flux. EPREM couples with MHD models such as ENLIL and computes energetic particle distributions based on the focused transport equation along a Lagrangian grid of nodes that propagate out with the solar wind. The coupled SEP models allow us to derive the longitudinal distribution of SEP profiles of different types of events throughout the heliosphere. The coupled ENLIL and SEP models allow us to derive the longitudinal distribution of SEP profiles of different types of events throughout the heliosphere. In this presentation we demonstrate several case studies of SEP event modeling at different observers based on WSA-ENLIL+Cone simulations.

  2. Modeling Secondary Neutral Helium in the Heliosphere

    International Nuclear Information System (INIS)

    Müller, Hans-Reinhard; Möbius, Eberhard; Wood, Brian E.

    2016-01-01

    An accurate, analytic heliospheric neutral test-particle code for helium atoms from the interstellar medium (ISM) is coupled to global heliospheric models dominated by hydrogen and protons from the solar wind and the ISM. This coupling enables the forward-calculation of secondary helium neutrals from first principles. Secondaries are produced predominantly in the outer heliosheath, upwind of the heliopause, by charge exchange of helium ions with neutral atoms. The forward model integrates the secondary production terms along neutral trajectories and calculates the combined neutral helium phase space density in the innermost heliosphere where it can be related to in-situ observations. The phase space density of the secondary component is lower than that of primary neutral helium, but its presence can change the analysis of primaries and the ISM, and can yield valuable insight into the characteristics of the plasma in the outer heliosheath. (paper)

  3. A Time-dependent Heliospheric Model Driven by Empirical Boundary Conditions

    Science.gov (United States)

    Kim, T. K.; Arge, C. N.; Pogorelov, N. V.

    2017-12-01

    Consisting of charged particles originating from the Sun, the solar wind carries the Sun's energy and magnetic field outward through interplanetary space. The solar wind is the predominant source of space weather events, and modeling the solar wind propagation to Earth is a critical component of space weather research. Solar wind models are typically separated into coronal and heliospheric parts to account for the different physical processes and scales characterizing each region. Coronal models are often coupled with heliospheric models to propagate the solar wind out to Earth's orbit and beyond. The Wang-Sheeley-Arge (WSA) model is a semi-empirical coronal model consisting of a potential field source surface model and a current sheet model that takes synoptic magnetograms as input to estimate the magnetic field and solar wind speed at any distance above the coronal region. The current version of the WSA model takes the Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model as input to provide improved time-varying solutions for the ambient solar wind structure. When heliospheric MHD models are coupled with the WSA model, density and temperature at the inner boundary are treated as free parameters that are tuned to optimal values. For example, the WSA-ENLIL model prescribes density and temperature assuming momentum flux and thermal pressure balance across the inner boundary of the ENLIL heliospheric MHD model. We consider an alternative approach of prescribing density and temperature using empirical correlations derived from Ulysses and OMNI data. We use our own modeling software (Multi-scale Fluid-kinetic Simulation Suite) to drive a heliospheric MHD model with ADAPT-WSA input. The modeling results using the two different approaches of density and temperature prescription suggest that the use of empirical correlations may be a more straightforward, consistent method.

  4. COUPLING OF CORONAL AND HELIOSPHERIC MAGNETOHYDRODYNAMIC MODELS: SOLUTION COMPARISONS AND VERIFICATION

    Energy Technology Data Exchange (ETDEWEB)

    Merkin, V. G. [The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Lionello, R.; Linker, J.; Török, T.; Downs, C. [Predictive Science, Inc., San Diego, CA 92121 (United States); Lyon, J. G., E-mail: slava.merkin@jhuapl.edu [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States)

    2016-11-01

    Two well-established magnetohydrodynamic (MHD) codes are coupled to model the solar corona and the inner heliosphere. The corona is simulated using the MHD algorithm outside a sphere (MAS) model. The Lyon–Fedder–Mobarry (LFM) model is used in the heliosphere. The interface between the models is placed in a spherical shell above the critical point and allows both models to work in either a rotating or an inertial frame. Numerical tests are presented examining the coupled model solutions from 20 to 50 solar radii. The heliospheric simulations are run with both LFM and the MAS extension into the heliosphere, and use the same polytropic coronal MAS solutions as the inner boundary condition. The coronal simulations are performed for idealized magnetic configurations, with an out-of-equilibrium flux rope inserted into an axisymmetric background, with and without including the solar rotation. The temporal evolution at the inner boundary of the LFM and MAS solutions is shown to be nearly identical, as are the steady-state background solutions, prior to the insertion of the flux rope. However, after the coronal mass ejection has propagated through the significant portion of the simulation domain, the heliospheric solutions diverge. Additional simulations with different resolution are then performed and show that the MAS heliospheric solutions approach those of LFM when run with progressively higher resolution. Following these detailed tests, a more realistic simulation driven by the thermodynamic coronal MAS is presented, which includes solar rotation and an azimuthally asymmetric background and extends to the Earth’s orbit.

  5. Heliospheric modulation of cosmic rays: model and observation

    Directory of Open Access Journals (Sweden)

    Gerasimova S.K.

    2017-03-01

    Full Text Available This paper presents the basic model of cosmic ray modulation in the heliosphere, developed in Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy of the Siberian Branch of the Russian Academy of Sciences. The model has only one free modulation parameter: the ratio of the regular magnetic field to the turbulent one. It may also be applied to the description of cosmic ray intensity variations in a wide energy range from 100 MeV to 100 GeV. Possible mechanisms of generation of the turbulent field are considered. The primary assumption about the electrical neutrality of the heliosphere appears to be wrong, and the zero potential needed to match the model with observations in the solar equatorial plane can be achieved if the frontal point of the heliosphere, which is flowed around by interstellar gas, lies near the plane. We have revealed that the abnormal rise of cosmic ray intensity at the end of solar cycle 23 is related to the residual modulation produced by the subsonic solar wind behind the front of a standing shock wave. The model is used to describe features of cosmic ray intensity variations in several solar activity cycles.

  6. Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

    International Nuclear Information System (INIS)

    Swaczyna, Paweł; Bzowski, Maciej

    2017-01-01

    Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2–130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smaller for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50–10 6 times smaller than the hydrogen ENA intensities observed by IBEX . The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.

  7. Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

    Energy Technology Data Exchange (ETDEWEB)

    Swaczyna, Paweł; Bzowski, Maciej, E-mail: pswaczyna@cbk.waw.pl [Space Research Centre of the Polish Academy of Sciences (CBK PAN), Bartycka 18A, 00-716 Warsaw (Poland)

    2017-09-10

    Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2–130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smaller for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50–10{sup 6} times smaller than the hydrogen ENA intensities observed by IBEX . The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.

  8. The Heliosphere in Space

    Science.gov (United States)

    Frisch, P. C.; Hanson, A. J.; Fu, P. C.

    2008-12-01

    A scientifically accurate visualization of the Journey of the Sun through deep space has been created in order to share the excitement of heliospheric physics and scientific discovery with the non-expert. The MHD heliosphere model of Linde (1998) displays the interaction of the solar wind with the interstellar medium for a supersonic heliosphere traveling through a low density magnetized interstellar medium. The camera viewpoint follows the solar motion through a virtual space of the Milky Way Galaxy. This space is constructed from real data placed in the three-dimensional solar neighborhood, and populated with Hipparcos stars in front of a precisely aligned image of the Milky Way itself. The celestial audio track of this three minute movie includes the music of the heliosphere, heard by the two Voyager satellites as 3 kHz emissions from the edge of the heliosphere. This short heliosphere visualization can be downloaded from http://www.cs.indiana.edu/~soljourn/pub/AstroBioScene7Sound.mov, and the full scientific data visualization of the Solar Journey is available commercially.

  9. Comparative Validation of Realtime Solar Wind Forecasting Using the UCSD Heliospheric Tomography Model

    Science.gov (United States)

    MacNeice, Peter; Taktakishvili, Alexandra; Jackson, Bernard; Clover, John; Bisi, Mario; Odstrcil, Dusan

    2011-01-01

    The University of California, San Diego 3D Heliospheric Tomography Model reconstructs the evolution of heliospheric structures, and can make forecasts of solar wind density and velocity up to 72 hours in the future. The latest model version, installed and running in realtime at the Community Coordinated Modeling Center(CCMC), analyzes scintillations of meter wavelength radio point sources recorded by the Solar-Terrestrial Environment Laboratory(STELab) together with realtime measurements of solar wind speed and density recorded by the Advanced Composition Explorer(ACE) Solar Wind Electron Proton Alpha Monitor(SWEPAM).The solution is reconstructed using tomographic techniques and a simple kinematic wind model. Since installation, the CCMC has been recording the model forecasts and comparing them with ACE measurements, and with forecasts made using other heliospheric models hosted by the CCMC. We report the preliminary results of this validation work and comparison with alternative models.

  10. A Snapshot of the Sun Near Solar Minimum: The Whole Heliosphere Interval

    Science.gov (United States)

    Thompson, Barbara J.; Gibson, Sarah E.; Schroeder, Peter C.; Webb, David F.; Arge, Charles N.; Bisi, Mario M.; de Toma, Giuliana; Emery, Barbara A.; Galvin, Antoinette B.; Haber, Deborah A.; hide

    2011-01-01

    We present an overview of the data and models collected for the Whole Heliosphere Interval, an international campaign to study the three-dimensional solar heliospheric planetary connected system near solar minimum. The data and models correspond to solar Carrington Rotation 2068 (20 March 16 April 2008) extending from below the solar photosphere, through interplanetary space, and down to Earth's mesosphere. Nearly 200 people participated in aspects of WHI studies, analyzing and interpreting data from nearly 100 instruments and models in order to elucidate the physics of fundamental heliophysical processes. The solar and inner heliospheric data showed structure consistent with the declining phase of the solar cycle. A closely spaced cluster of low-latitude active regions was responsible for an increased level of magnetic activity, while a highly warped current sheet dominated heliospheric structure. The geospace data revealed an unusually high level of activity, driven primarily by the periodic impingement of high-speed streams. The WHI studies traced the solar activity and structure into the heliosphere and geospace, and provided new insight into the nature of the interconnected heliophysical system near solar minimum.

  11. Plasmas in the outer heliosphere

    Science.gov (United States)

    Belcher, J. W.; Richardson, J. D.; Lazarus, A. J.; Gazis, P. R.; Barnes, A.

    1995-01-01

    We review the observed properties of the solar wind in the outer heliosphere, including observations from Voyager and the Pioneers, as well as from inner heliospheric probes as appropriate. These observations are crucial to modeling of the heliosphere and its interactions with the interstellar medium, since the wind ram pressure and its temporal variations are important in understanding the distance to the termination shock and heliopause and how those boundaries might vary in time. We focus on results since Solar Wind 7. Among the issues we will discuss are: (1) the time scales for and statistical properties of variations in the ram pressure in the outer heliosphere, and how those variations might affect the morphology of the heliospheric/interstellar medium interface; (2) the question of possible solar wind slowing in the outer heliosphere due to the pick-up of interstellar ions; (3) the issue of whether there is bulk heating of the solar wind associated either with interstellar ion pick-up or with continued heating due to stream-stream interactions; (4) evidence for latitudinal variations in solar wind properties; and (5) the 1.3 year periodicities apparent in the outer heliosphere, and the close correspondence with similar variations seen with inner heliospheric probes.

  12. Modeling of coronal mass ejections with the STEREO heliospheric imagers verified with in situ observations by the Heliophysics System Observatory

    Science.gov (United States)

    Möstl, Christian; Isavnin, Alexey; Kilpua, Emilia; Bothmer, Volker; Mrotzek, Nicolas; Boakes, Peter; Rodriguez, Luciano; Krupar, Vratislav; Eastwood, Jonathan; Davies, Jackie; Harrison, Richard; Barnes, David; Winslow, Reka; Helcats Team

    2017-04-01

    We present the first study to verify modeling of CMEs as observed by the heliospheric imagers on the two STEREO spacecraft with a large scale dataset of in situ plasma and magnetic field observations from the Heliophysics System Observatory, including MESSENGER, VEX, Wind, and the in situ measurements on the two STEREO spacecraft. To this end, we have established a new interplanetary CME catalog (ICMECAT) for these spacecraft by gathering and updating individual ICME lists. In addition, we have re-calculated the in situ parameters in a consistent way, resulting in 668 events observed between 2007-2015. We then calculated the efficacy of the STEREO/HI instruments for predicting (in hindsight) with the SSEF30 model the arrival time and speed of CMEs as well as hit/miss ratios. We also show how ICMECAT gives decent statistics concerning CME impacts on all of the terrestrial planets, including Mars. The results show some major implications for future heliospheric imagers which may be used for space weather forecasting. Our effort should also serve as a baseline for the upcoming new era in heliospheric science with Solar Orbiter, Solar Probe Plus, BepiColombo returning partly comparable observations in the next decade. The presented work has received funding from the European Union Seventh Framework Programme (FP7/ 2007-2013) under grant agreement No. 606692 [HELCATS].

  13. Modeling observations of solar coronal mass ejections with heliospheric imagers verified with the Heliophysics System Observatory.

    Science.gov (United States)

    Möstl, C; Isavnin, A; Boakes, P D; Kilpua, E K J; Davies, J A; Harrison, R A; Barnes, D; Krupar, V; Eastwood, J P; Good, S W; Forsyth, R J; Bothmer, V; Reiss, M A; Amerstorfer, T; Winslow, R M; Anderson, B J; Philpott, L C; Rodriguez, L; Rouillard, A P; Gallagher, P; Nieves-Chinchilla, T; Zhang, T L

    2017-07-01

    We present an advance toward accurately predicting the arrivals of coronal mass ejections (CMEs) at the terrestrial planets, including Earth. For the first time, we are able to assess a CME prediction model using data over two thirds of a solar cycle of observations with the Heliophysics System Observatory. We validate modeling results of 1337 CMEs observed with the Solar Terrestrial Relations Observatory (STEREO) heliospheric imagers (HI) (science data) from 8 years of observations by five in situ observing spacecraft. We use the self-similar expansion model for CME fronts assuming 60° longitudinal width, constant speed, and constant propagation direction. With these assumptions we find that 23%-35% of all CMEs that were predicted to hit a certain spacecraft lead to clear in situ signatures, so that for one correct prediction, two to three false alarms would have been issued. In addition, we find that the prediction accuracy does not degrade with the HI longitudinal separation from Earth. Predicted arrival times are on average within 2.6 ± 16.6 h difference of the in situ arrival time, similar to analytical and numerical modeling, and a true skill statistic of 0.21. We also discuss various factors that may improve the accuracy of space weather forecasting using wide-angle heliospheric imager observations. These results form a first-order approximated baseline of the prediction accuracy that is possible with HI and other methods used for data by an operational space weather mission at the Sun-Earth L5 point.

  14. TRAJECTORIES AND DISTRIBUTION OF INTERSTELLAR DUST GRAINS IN THE HELIOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Slavin, Jonathan D. [Harvard-Smithsonian Center for Astrophysics, MS 83, 60 Garden Street, Cambridge, MA 02138 (United States); Frisch, Priscilla C. [Department of Astronomy and Astrophysics, University of Chicago, 5460 S. Ellis Avenue, Chicago, IL 60637 (United States); Mueller, Hans-Reinhard [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Heerikhuisen, Jacob; Pogorelov, Nikolai V. [Department of Physics and Center for Space Physics and Aeronomic Research, University of Alabama, Huntsville, AL 35899 (United States); Reach, William T. [Universities Space Research Association, MS 211-3, Moffett Field, CA 94035 (United States); Zank, Gary [Department of Physics and Center for Space Plasma and Aeronomic Research, University of Alabama, Huntsville, AL 35805 (United States)

    2012-11-20

    The solar wind carves a bubble in the surrounding interstellar medium (ISM) known as the heliosphere. Charged interstellar dust grains (ISDG) encountering the heliosphere may be diverted around the heliopause or penetrate it depending on their charge-to-mass ratio. We present new calculations of trajectories of ISDG in the heliosphere, and the dust density distributions that result. We include up-to-date grain charging calculations using a realistic UV radiation field and full three-dimensional magnetohydrodynamic fluid + kinetic models for the heliosphere. Models with two different (constant) polarities for the solar wind magnetic field (SWMF) are used, with the grain trajectory calculations done separately for each polarity. Small grains a {sub gr} {approx}< 0.01 {mu}m are completely excluded from the inner heliosphere. Large grains, a {sub gr} {approx}> 1.0 {mu}m, pass into the inner solar system and are concentrated near the Sun by its gravity. Trajectories of intermediate size grains depend strongly on the SWMF polarity. When the field has magnetic north pointing to ecliptic north, the field de-focuses the grains resulting in low densities in the inner heliosphere, while for the opposite polarity the dust is focused near the Sun. The ISDG density outside the heliosphere inferred from applying the model results to in situ dust measurements is inconsistent with local ISM depletion data for both SWMF polarities but is bracketed by them. This result points to the need to include the time variation in the SWMF polarity during grain propagation. Our results provide valuable insights for interpretation of the in situ dust observations from Ulysses.

  15. The long-term variability of cosmic ray protons in the heliosphere: A modeling approach

    Directory of Open Access Journals (Sweden)

    M.S. Potgieter

    2013-05-01

    Full Text Available Galactic cosmic rays are charged particles created in our galaxy and beyond. They propagate through interstellar space to eventually reach the heliosphere and Earth. Their transport in the heliosphere is subjected to four modulation processes: diffusion, convection, adiabatic energy changes and particle drifts. Time-dependent changes, caused by solar activity which varies from minimum to maximum every ∼11 years, are reflected in cosmic ray observations at and near Earth and along spacecraft trajectories. Using a time-dependent compound numerical model, the time variation of cosmic ray protons in the heliosphere is studied. It is shown that the modeling approach is successful and can be used to study long-term modulation cycles.

  16. A MODEL OF THE HELIOSPHERE WITH JETS

    International Nuclear Information System (INIS)

    Drake, J. F.; Swisdak, M.; Opher, M.

    2015-01-01

    An analytic model of the heliosheath (HS) between the termination shock (TS) and the heliopause (HP) is developed in the limit in which the interstellar flow and magnetic field are neglected. The heliosphere in this limit is axisymmetric and the overall structure of the HS and HP is controlled by the solar magnetic field even in the limit in which the ratio of the plasma to magnetic field pressure, β = 8πP/B 2 , in the HS is large. The tension of the solar magnetic field produces a drop in the total pressure between the TS and the HP. This same pressure drop accelerates the plasma flow downstream of the TS into the north and south directions to form two collimated jets. The radii of these jets are controlled by the flow through the TS and the acceleration of this flow by the magnetic field—a stronger solar magnetic field boosts the velocity of the jets and reduces the radii of the jets and the HP. MHD simulations of the global heliosphere embedded in a stationary interstellar medium match well with the analytic model. The results suggest that mechanisms that reduce the HS plasma pressure downstream of the TS can enhance the jet outflow velocity and reduce the HP radius to values more consistent with the Voyager 1 observations than in current global models

  17. TRAJECTORIES AND DISTRIBUTION OF INTERSTELLAR DUST GRAINS IN THE HELIOSPHERE

    International Nuclear Information System (INIS)

    Slavin, Jonathan D.; Frisch, Priscilla C.; Müller, Hans-Reinhard; Heerikhuisen, Jacob; Pogorelov, Nikolai V.; Reach, William T.; Zank, Gary

    2012-01-01

    The solar wind carves a bubble in the surrounding interstellar medium (ISM) known as the heliosphere. Charged interstellar dust grains (ISDG) encountering the heliosphere may be diverted around the heliopause or penetrate it depending on their charge-to-mass ratio. We present new calculations of trajectories of ISDG in the heliosphere, and the dust density distributions that result. We include up-to-date grain charging calculations using a realistic UV radiation field and full three-dimensional magnetohydrodynamic fluid + kinetic models for the heliosphere. Models with two different (constant) polarities for the solar wind magnetic field (SWMF) are used, with the grain trajectory calculations done separately for each polarity. Small grains a gr ∼ gr ∼> 1.0 μm, pass into the inner solar system and are concentrated near the Sun by its gravity. Trajectories of intermediate size grains depend strongly on the SWMF polarity. When the field has magnetic north pointing to ecliptic north, the field de-focuses the grains resulting in low densities in the inner heliosphere, while for the opposite polarity the dust is focused near the Sun. The ISDG density outside the heliosphere inferred from applying the model results to in situ dust measurements is inconsistent with local ISM depletion data for both SWMF polarities but is bracketed by them. This result points to the need to include the time variation in the SWMF polarity during grain propagation. Our results provide valuable insights for interpretation of the in situ dust observations from Ulysses.

  18. Galactic Cosmic-ray Transport in the Global Heliosphere: A Four-Dimensional Stochastic Model

    Science.gov (United States)

    Florinski, V.

    2009-04-01

    We study galactic cosmic-ray transport in the outer heliosphere and heliosheath using a newly developed transport model based on stochastic integration of the phase-space trajectories of Parker's equation. The model employs backward integration of the diffusion-convection transport equation using Ito calculus and is four-dimensional in space+momentum. We apply the model to the problem of galactic proton transport in the heliosphere during a negative solar minimum. Model results are compared with the Voyager measurements of galactic proton radial gradients and spectra in the heliosheath. We show that the heliosheath is not as efficient in diverting cosmic rays during solar minima as predicted by earlier two-dimensional models.

  19. The Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project

    Science.gov (United States)

    Barnes, D.; Harrison, R. A.; Davies, J. A.; Perry, C. H.; Moestl, C.; Rouillard, A.; Bothmer, V.; Rodriguez, L.; Eastwood, J. P.; Kilpua, E.; Gallagher, P.; Odstrcil, D.

    2017-12-01

    Understanding solar wind evolution is fundamental to advancing our knowledge of energy and mass transport in the solar system, whilst also being crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of solar wind evolution, by enabling direct and continuous observation of both transient and background components of the solar wind as they propagate from the Sun to 1 AU and beyond. The recently completed, EU-funded FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project (1st May 2014 - 30th April 2017) combined European expertise in heliospheric imaging, built up over the last decade in particular through leadership of the Heliospheric Imager (HI) instruments aboard NASA's STEREO mission, with expertise in solar and coronal imaging as well as the interpretation of in-situ and radio diagnostic measurements of solar wind phenomena. HELCATS involved: (1) the cataloguing of transient (coronal mass ejections) and background (stream/corotating interaction regions) solar wind structures observed by the STEREO/HI instruments, including estimates of their kinematic properties based on a variety of modelling techniques; (2) the verification of these kinematic properties through comparison with solar source observations and in-situ measurements at multiple points throughout the heliosphere; (3) the assessment of the potential for initialising numerical models based on the derived kinematic properties of transient and background solar wind components; and (4) the assessment of the complementarity of radio observations (Type II radio bursts and interplanetary scintillation) in the detection and analysis of heliospheric structure in combination with heliospheric imaging observations. In this presentation, we provide an overview of the HELCATS project emphasising, in particular, the principal achievements and legacy of this unprecedented project.

  20. The Energetic Neutral Atoms of the "Croissant" Heliosphere with Jets

    Science.gov (United States)

    Kornbleuth, M. Z.; Opher, M.; Michael, A.

    2017-12-01

    Opher et al. (2015) suggests the heliosphere may have two jets in the tail-ward direction driven to the north and south. This new model, the "Croissant Heliosphere", is in contrast to the classically accepted view of a comet-like tail. We investigate the effect of the heliosphere with jets model on energetic neutral atom (ENA) maps. Regardless of the existence of a split tail, other models show heliosheath plasma confined by the toroidal magnetic field in a "slinky" structure, similar to astrophysical jets bent by the interstellar medium. Therefore, the confinement of the plasma should appear in the ENA maps. ENA maps from the Interstellar Boundary Explorer (IBEX) have recently shown two high latitude lobes with excess ENA flux at higher energies in the tail of the heliosphere. These lobes could be a signature of the two jet structure of the heliosphere, while some have argued they are cause by the fast/slow solar wind profile. Here we present the ENA maps of the "Croissant Heliosphere" using initially a uniform solar wind. We incorporate pick-up ions (PUIs) into our model based on the kinetic modeling of Malama et al. (2006). We include the extinction of PUIs in the heliosheath and describe a locally created PUI population resulting from this extinction process. Additionally, we include the angular dependence of the PUIs based on the work of Vasyliunas & Siscoe (1976). With our model, we find that, in the presence of a uniform solar wind, the "heliosphere with jets" model is able to qualitatively reproduce the lobe structure of the tail seen in IBEX measurements. Turbulence also manifests itself within the lobes of the simulated ENA maps on the order of years. Finally we will present ENA maps using a time-dependent model of the heliosphere with the inclusion of solar cycle.

  1. Modeling observations of solar coronal mass ejections with heliospheric imagers verified with the eliophysics System Observatory

    Czech Academy of Sciences Publication Activity Database

    Möstl, C.; Isavnin, A.; Boakes, P. D.; Kilpua, E. K. J.; Davies, J. A.; Harrison, R. A.; Barnes, D.; Krupař, Vratislav; Eastwood, J.; Good, S. W.; Forsyth, R. J.; Bothmer, V.; Reiss, M. A.; Amerstorfer, T.; Winslow, R. M.; Anderson, B.J.; Philpott, L. C.; Rodriguez, L.; Rouillard, A. P.; Gallagher, P.; Nieves-Chinchilla, T.; Zhang, T. L.

    2017-01-01

    Roč. 15, č. 7 (2017), s. 955-970 ISSN 1539-4956 R&D Projects: GA ČR(CZ) GJ17-06818Y Institutional support: RVO:68378289 Keywords : space weather * coronal mass ejections * STEREO * heliospheric imagers * Heliophysics System Observatory * heliophysics Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) http://onlinelibrary.wiley.com/doi/10.1002/2017SW001614/full

  2. MULTIFRACTAL STRUCTURES DETECTED BY VOYAGER 1 AT THE HELIOSPHERIC BOUNDARIES

    International Nuclear Information System (INIS)

    Macek, W. M.; Wawrzaszek, A.; Burlaga, L. F.

    2014-01-01

    To better understand the dynamics of turbulent systems, we have proposed a phenomenological model based on a generalized Cantor set with two rescaling and one weight parameters. In this Letter, using recent Voyager 1 magnetic field data, we extend our two-scale multifractal analysis further in the heliosheath beyond the heliospheric termination shock, and even now near the heliopause, when entering the interstellar medium for the first time in human history. We have identified the scaling inertial region for magnetized heliospheric plasma between the termination shock and the heliopause. We also show that the degree of multifractality decreases with the heliocentric distance and is still modulated by the phases of the solar cycle in the entire heliosphere including the heliosheath. Moreover, we observe the change of scaling toward a nonintermittent (nonmultifractal) behavior in the nearby interstellar medium, just beyond the heliopause. We argue that this loss of multifractal behavior could be a signature of the expected crossing of the heliopause by Voyager 2 in the near future. The results obtained demonstrate that our phenomenological multifractal model exhibits some properties of intermittent turbulence in the solar system plasmas, and we hope that it could shed light on universal characteristics of turbulence

  3. MULTIFRACTAL STRUCTURES DETECTED BY VOYAGER 1 AT THE HELIOSPHERIC BOUNDARIES

    Energy Technology Data Exchange (ETDEWEB)

    Macek, W. M. [Faculty of Mathematics and Natural Sciences, Cardinal Stefan Wyszyński University, Wóycickiego 1/3, 01-938 Warsaw (Poland); Wawrzaszek, A. [Space Research Centre, Polish Academy of Sciences, Bartycka 18 A, 00-716 Warszawa (Poland); Burlaga, L. F., E-mail: macek@cbk.waw.pl, E-mail: anna.wawrzaszek@cbk.waw.pl, E-mail: lburlagahsp@verizon.net [NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 (United States)

    2014-10-01

    To better understand the dynamics of turbulent systems, we have proposed a phenomenological model based on a generalized Cantor set with two rescaling and one weight parameters. In this Letter, using recent Voyager 1 magnetic field data, we extend our two-scale multifractal analysis further in the heliosheath beyond the heliospheric termination shock, and even now near the heliopause, when entering the interstellar medium for the first time in human history. We have identified the scaling inertial region for magnetized heliospheric plasma between the termination shock and the heliopause. We also show that the degree of multifractality decreases with the heliocentric distance and is still modulated by the phases of the solar cycle in the entire heliosphere including the heliosheath. Moreover, we observe the change of scaling toward a nonintermittent (nonmultifractal) behavior in the nearby interstellar medium, just beyond the heliopause. We argue that this loss of multifractal behavior could be a signature of the expected crossing of the heliopause by Voyager 2 in the near future. The results obtained demonstrate that our phenomenological multifractal model exhibits some properties of intermittent turbulence in the solar system plasmas, and we hope that it could shed light on universal characteristics of turbulence.

  4. Cosmic-Ray Transport in Heliospheric Magnetic Structures. II. Modeling Particle Transport through Corotating Interaction Regions

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Andreas [Université Libre de Bruxelles, Service de Physique Statistique et des Plasmas, CP 231, B-1050 Brussels (Belgium); Wiengarten, Tobias; Fichtner, Horst [Institut für Theoretische Physik IV, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Effenberger, Frederic [Department of Physics and KIPAC, Stanford University, Stanford, CA 94305 (United States); Kühl, Patrick; Heber, Bernd [Institut für Experimentelle und Angewandte Physik, Christian-Albrecht-Universität zu Kiel, D-24098 Kiel (Germany); Raath, Jan-Louis; Potgieter, Marius S. [Centre for Space Research, North-West University, 2520 Potchefstroom (South Africa)

    2017-03-01

    The transport of cosmic rays (CRs) in the heliosphere is determined by the properties of the solar wind plasma. The heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric CR transport are structures such as corotating interaction regions (CIRs), which, due to the enhancement of the magnetic field strength and magnetic fluctuations within and due to the associated shocks as well as stream interfaces, do influence the CR diffusion and drift. In a three-fold series of papers, we investigate these effects by modeling inner-heliospheric solar wind conditions with the numerical magnetohydrodynamic (MHD) framework Cronos (Wiengarten et al., referred as Paper I), and the results serve as input to a transport code employing a stochastic differential equation approach (this paper). While, in Paper I, we presented results from 3D simulations with Cronos, the MHD output is now taken as an input to the CR transport modeling. We discuss the diffusion and drift behavior of Galactic cosmic rays using the example of different theories, and study the effects of CIRs on these transport processes. In particular, we point out the wide range of possible particle fluxes at a given point in space resulting from these different theories. The restriction of this variety by fitting the numerical results to spacecraft data will be the subject of the third paper of this series.

  5. Modulation of Galactic Cosmic Rays in the Inner Heliosphere over Solar Cycles

    Science.gov (United States)

    Shen, Z.-N.; Qin, G.

    2018-02-01

    The 11- and 22-year modulation of galactic cosmic rays (GCRs) in the inner heliosphere is studied using a numerical model developed by Qin and Shen in 2017. Based on the numerical solutions of Parker’s transport equations, the model incorporates a modified Parker heliospheric magnetic field, a locally static time-delayed heliosphere, and a time-dependent diffusion coefficients model in which an analytical expression of the variation of magnetic turbulence magnitude throughout the inner heliosphere is applied. Furthermore, during solar maximum, the solar magnetic polarity is determined randomly with the possibility of A > 0 decided by the percentage of the solar north polar magnetic field being outward and the solar south polar magnetic field being inward. The computed results are compared at various energies with several GCR observations, e.g., the Interplanetary Monitoring Platform 8 (IMP 8), EPHIN on board the Solar and Heliospheric Observatory (SOHO), Ulysses, and Voyager 1 and 2, and they show good agreement. We show that our model has successfully reproduced the 11- and 22-year modulation cycles.

  6. Magnetized jets driven by the Sun: The structure of the heliosphere revisited—Updates

    Energy Technology Data Exchange (ETDEWEB)

    Opher, M., E-mail: mopher@bu.edu [Astronomy Department, Boston University, Boston, Massachusetts 02215 (United States); Drake, J. F.; Swisdak, M. [University of Maryland, College Park, Maryland 20742 (United States); Zieger, B. [Center for Space Physics, Boston University, Massachusetts 02215 (United States); Toth, G. [Department of Climate and Space, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2016-05-15

    As the solar system moves through the interstellar medium, the solar wind is deflected forming the heliosphere. The standard picture of the heliosphere is a comet-shape like structure with the tail extending for 1000s of astronomical units. This standard picture stems from a view where magnetic forces are negligible and the solar magnetic field is convected passively down the tail. Recently, we showed that the magnetic tension of the solar magnetic field plays a crucial role on organizing the solar wind in the heliosheath into two jet-like structures. The two jets are separated by the interstellar medium that flows between them. The heliosphere then has a “croissant”-like shape where the distance to the heliopause downtail is almost the same as towards the nose. This new view of the heliosphere is in agreement with the energetic neutral atoms maps taken by the Interstellar Boundary Explorer and INCA/CASSINI. We developed as well an analytic model of the heliosheath in the axisymmetric limit that shows how the magnetic tension force is the driver for the north and south jets. We confirmed that the formation of these jets with magnetohydrodynamic (MHD) simulations. The main reason why previous global MHD simulations did not see these jets is due to spurious magnetic dissipation that was present at the heliospheric current sheet. We instead kept the same polarity for the interplanetary (solar) magnetic field in both the northern and southern hemispheres, eliminating spurious magnetic dissipation effects at the heliospheric current sheet. In this paper, we extend these previous results to include additional cases where we used: (a) weaker solar magnetic field; (b) solar magnetic field that reverses polarity at the solar equator in the axisymmetric limit; and (c) slower motion through the interstellar system. We discuss as well future challenges regarding the structure of the heliosphere.

  7. Observational Evidence For The Comet-Like Heliosphere

    Science.gov (United States)

    Bzowski, M.; Czechowski, A.; Funsten, H. O.; Grygorczuk, J.; Heerikhuisen, J.; Kubiak, M. A.; Moebius, E.; McComas, D. J.; Schwadron, N.; Sokol, J. M.; Swaczyna, P.; Zirnstein, E.

    2017-12-01

    The shape of the heliosphere is a subject of ongoing debate. The traditional comet-like image has recently been challenged by ideas of croissant- or bubble-like forms. Here we seek to resolve this debate by confronting available observational evidence with global modeling. Several MHD models of a comet-like heliosphere were used to simulate the radius and center of the IBEX Ribbon to fit the direction and intensity of the interstellar magnetic field (ISMF). These models assumed the secondary ENA emission mechanism, which was recently strengthened due to direct measurement of the distance to the Ribbon source most likely just beyond the heliopause. The same mechanism explains the dependence of the Ribbon center position on energy due to the latitudinal structure of solar wind. The obtained ISMF vector agrees among these models and is consistent with the draped IMF measured by Voyager. Independently, we have shown by modeling that the Warm Breeze discovered by IBEX is naturally created in the outer heliosheath due to charge-exchange between interstellar He+ ions and He atoms. Now we simulate the Warm Breeze for various directions and intensities of the local IMF and we find that the simulation results are in best agreement with IBEX observations for the IMF vector obtained from the above-mentioned Ribbon analyses and Voyager measurements. These arguments, along with the co-planarity of the inflow directions of interstellar neutral H, He, O, and the Warm Breeze, directions of the Ribbon center and ISMF, as well as measurements of the plasma flow directions in the IHS by Voyager 2 indicate the existence of a common plane of approximate mirror symmetry of the heliosphere, defined by the directions of ISMF and the Sun's motion through the local interstellar medium. This suggests that the global structure of the outer heliosphere mostly results from the conditions in the local interstellar medium and the Sun's velocity. This evidence, obtained from very different

  8. Modelling injection rates of PUIs from photoionization using kinetic simulations of interstellar neutrals traversing the heliosphere

    Science.gov (United States)

    Keilbach, D.; Drews, C.; Taut, A.; Wimmer-Schweingruber, R. F.

    2016-12-01

    Recent studies of the inflow direction of the local insterstellar medium from PUI density distributions have shown that the extrema of the longitudinal distribution of PUI velocities (with respect to the solar wind speed) can be attributed to the radial velocity of the interstellar neutral seed population and is symmetric around the inflow direction of the local interstellar medium. This work is aimed to model pickup ion injection rates from photoionization (which is the main process of interstellar PUI production) throughout the heliosphere. To that end a seed population of interstellar neutrals is injected into a model heliosphere at 60 AU distance from the sun, whereas each particle's initial speed is given by a maxwellian distribution at a temperature of 1 eV and an inflow speed of 22 km/s. Then the density of the interstellar neutrals is integrated over the model heliosphere, while the movement of the neutrals is simulated using timestep methods. To model the focusing of the interstellar neutral trajectories from the sun's gravitational potential the model heliosphere contains a central gravitational potential.Each neutral test particle can be ionized via photoionization with a per-timestep probability antiproportional to the neutral's distance to the sun squared. By tracking the ionization rate location-dependently, PUI injection rates have been determined. Therefore using these simulations the density distributions of different species of interstellar neutrals have been calculated. In addition location-dependent injection rates of different species of PUIs have been calculated, which show an increased rate of PUI production in the focusing cone region (e.g. for He+ PUIs), but also in the crescent region (e.g. for O+ PUIs).Furthermore the longitudinal distribution of the neutrals' velocity at 1 AU is calculated from the simulation's results in order to estimate the PUI cut-off as a function of ecliptic longitude. Figure: Simulated He neutral density (left

  9. ADVECTIVE TRANSPORT OF INTERSTELLAR PLASMA INTO THE HELIOSPHERE ACROSS THE RECONNECTING HELIOPAUSE

    International Nuclear Information System (INIS)

    Strumik, M.; Grzedzielski, S.; Czechowski, A.; Macek, W. M.; Ratkiewicz, R.

    2014-01-01

    We discuss results of magnetohydrodynamical model simulations of plasma dynamics in the proximity of the heliopause (HP). The model is shown to fit details of the magnetic field variations observed by the Voyager 1 spacecraft during the transition from the heliosphere to the local interstellar medium (LISM). We propose an interpretation of magnetic field structures observed by Voyager 1 in terms of fine-scale physical processes. Our simulations reveal an effective transport mechanism of relatively dense LISM plasma across the reconnecting HP into the heliosphere. The mechanism is associated with annihilation of magnetic sectors in the heliospheric plasma near the HP

  10. The Sun's Dynamic Influence on the Outer Heliosphere, the Heliosheath, and the Local Interstellar Medium

    International Nuclear Information System (INIS)

    Intriligator, D S; Sun, W; Detman, T; Miller, W D; Intriligator, J; Dryer, M; Deehr, C; Webber, W; Gloeckler, G

    2016-01-01

    The Sun has been observed for many years to be a dynamic influence in the heliosphere, and as the Voyager missions have continued long after achieving their original goals of observing the major planets they have provided the first in situ observations of the effects of solar activity in the heliosheath (HS), and the nearest portions of the local Interstellar Medium (LISM). Comparing these observations with models provides key insights. We employ two three-dimensional (3D) time-dependent models that simulate the propagation of shocks, other specific features, and the background solar wind throughout the heliosphere, starting with the solar background and solar event boundary conditions near the Sun at 2.5 Rs. The Hybrid Heliospheric Modeling System with Pickup Protons (HHMS-PI) is a 3D time- dependent Magnetohydrodynamic (MHD) simulation. HAFSS (HAF Solar Surface) is a 3D time-dependent kinematic simulation. Comparing our models with the observations indicates that solar effects are seen in the heliosphere, the HS, and the LISM in in-situ spacecraft measurements of plasma, magnetic field, energetic particles, cosmic rays, and plasma waves. There is quantitative agreement (at ACE, Ulysses, VI, V2) with data (e.g., solar wind, IMF, Ulysses SWICS pickup protons (PUPs)). Propagating shocks are slowed due to PUPs. The 3D locations of solar events and of various spacecraft are key to understanding the 3D propagation and timing of shocks, other specific features, and gradients throughout the heliosphere, HS, and LISM. (paper)

  11. The Heliosphere through the Solar Activity Cycle

    CERN Document Server

    Balogh, André; Suess, Steven T

    2008-01-01

    Understanding how the Sun changes though its 11-year sunspot cycle and how these changes affect the vast space around the Sun – the heliosphere – has been one of the principal objectives of space research since the advent of the space age. This book presents the evolution of the heliosphere through an entire solar activity cycle. The last solar cycle (cycle 23) has been the best observed from both the Earth and from a fleet of spacecraft. Of these, the joint ESA-NASA Ulysses probe has provided continuous observations of the state of the heliosphere since 1990 from a unique vantage point, that of a nearly polar orbit around the Sun. Ulysses’ results affect our understanding of the heliosphere from the interior of the Sun to the interstellar medium - beyond the outer boundary of the heliosphere. Written by scientists closely associated with the Ulysses mission, the book describes and explains the many different aspects of changes in the heliosphere in response to solar activity. In particular, the authors...

  12. A model for heliospheric flux-ropes

    Science.gov (United States)

    Nieves-Chinchilla, T.; Linton, M.; Vourlidas, A.; Hidalgo, M. A. U.

    2017-12-01

    This work is presents an analytical flux-rope model, which explores different levels of complexity starting from a circular-cylindrical geometry. The framework of this series of models was established by Nieves-Chinchilla et al. 2016 with the circular-cylindrical analytical flux rope model. The model attempts to describe the magnetic flux rope topology with distorted cross-section as a possible consequence of the interaction with the solar wind. In this model, the flux rope is completely described in a non-orthogonal geometry. The Maxwell equations are solved using tensor calculus consistent with the geometry chosen, invariance along the axial direction, and with the assumption of no radial current density. The model is generalized in terms of the radial and azimuthal dependence of the poloidal current density component and axial current density component. The misalignment between current density and magnetic field is studied in detail for several example profiles of the axial and poloidal current density components. This theoretical analysis provides a map of the force distribution inside of the flux-rope. For reconstruction of the heliospheric flux-ropes, the circular-cylindrical reconstruction technique has been adapted to the new geometry and applied to in situ ICMEs with a flux-rope entrained and tested with cases with clear in situ signatures of distortion. The model adds a piece in the puzzle of the physical-analytical representation of these magnetic structures that should be evaluated with the ultimate goal of reconciling in-situ reconstructions with imaging 3D remote sensing CME reconstructions. Other effects such as axial curvature and/or expansion could be incorporated in the future to fully understand the magnetic structure.

  13. Cosmic ray transport in heliospheric magnetic structures. I. Modeling background solar wind using the CRONOS magnetohydrodynamic code

    Energy Technology Data Exchange (ETDEWEB)

    Wiengarten, T.; Kleimann, J.; Fichtner, H. [Institut für Theoretische Physik IV, Ruhr-Universität Bochum (Germany); Kühl, P.; Kopp, A.; Heber, B. [Institut für Experimentelle und Angewandte Physik, Christian-Albrecht-Universität zu Kiel (Germany); Kissmann, R. [Institut für Astro- und Teilchenphysik, Universität Innsbruck (Austria)

    2014-06-10

    The transport of energetic particles such as cosmic rays is governed by the properties of the plasma being traversed. While these properties are rather poorly known for galactic and interstellar plasmas due to the lack of in situ measurements, the heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric transport of energetic particles are structures such as corotating interaction regions, which, due to strongly enhanced magnetic field strengths, turbulence, and associated shocks, can act as diffusion barriers on the one hand, but also as accelerators of low energy CRs on the other hand as well. In a two-fold series of papers, we investigate these effects by modeling inner-heliospheric solar wind conditions with a numerical magnetohydrodynamic (MHD) setup (this paper), which will serve as an input to a transport code employing a stochastic differential equation approach (second paper). In this first paper, we present results from 3D MHD simulations with our code CRONOS: for validation purposes we use analytic boundary conditions and compare with similar work by Pizzo. For a more realistic modeling of solar wind conditions, boundary conditions derived from synoptic magnetograms via the Wang-Sheeley-Arge (WSA) model are utilized, where the potential field modeling is performed with a finite-difference approach in contrast to the traditional spherical harmonics expansion often utilized in the WSA model. Our results are validated by comparing with multi-spacecraft data for ecliptical (STEREO-A/B) and out-of-ecliptic (Ulysses) regions.

  14. Cosmic Ray Modulation in the Outer Heliosphere During the Minimum of Solar Cycle 23/24

    Science.gov (United States)

    Adams, James H., Jr.; Florinski, V.; Washimi, H.; Pogorelov, N. V.

    2011-01-01

    We report a next generation model of galactic cosmic ray (GCR) transport in the three dimensional heliosphere. Our model is based on an accurate three-dimensional representation of the heliospheric interface. This representation is obtained by taking into account the interaction between partially ionized, magnetized plasma flows of the solar wind and the local interstellar medium. Our model reveals that after entering the heliosphere GCRs are stored in the heliosheath for several years. The preferred GCR entry locations are near the nose of the heliopause and at high latitudes. Low-energy (hundreds of MeV) galactic ions observed in the heliosheath have spent, on average, a longer time in the solar wind than those observed in the inner heliosphere, which would explain their cooled-off spectra at these energies. We also discuss radial gradients in the heliosheath and the implications for future Voyager observations.

  15. Solar Dynamics and Its Effects on the Heliosphere and Earth

    CERN Document Server

    Baker, D. N; Schwartz, S. J; Schwenn, R; Steiger, R

    2007-01-01

    The SOHO and Cluster missions form a single ESA cornerstone. Yet they observe very different regions in our solar system: the solar atmosphere on one hand and the Earth’s magnetosphere on the other. At the same time the Ulysses mission provides observations in the third dimension of the heliosphere, and many others add to the picture from the Lagrangian point L1 to the edge of the heliosphere. It is the aim of this ISSI volume to tie these observations together in addressing the topic of Solar Dynamics and its Effects on the Heliosphere and Earth, thus contributing to the International Living With a Star (ILWS) program. The volume starts out with an assessment and description of the reasons for solar dynamics and how it couples into the heliosphere. The three subsequent sections are each devoted to following one chain of events from the Sun all the way to the Earth’s magnetosphere and ionosphere: The normal solar wind chain, the chain associated with coronal mass ejections, and the solar energetic particl...

  16. IBEX Discoveries of the Global Heliosphere from Energetic Neutral Atoms and Preparations for IMAP

    Science.gov (United States)

    Schwadron, N.

    2015-12-01

    Our piece of cosmic real-estate, the heliosphere, is the domain of all human existence -- an astrophysical case-history of the successful evolution of life in a habitable system. By exploring our global heliosphere and its myriad interactions, we develop key physical knowledge of the interstellar interactions that influence exoplanetary habitability as well the history and destiny of our solar system. IBEX was the first mission to explore the global heliosphere and in concert with Voyager 1 and Voyager 2 is discovering a fundamentally new and uncharted physical domain of the outer heliosphere. In parallel, Cassini/INCA maps the global heliosphere at energies (~5-55 KeV) above those measured by IBEX. The enigmatic IBEX ribbon and the INCA belt were unanticipated discoveries demonstrating that much of what we know or think we understand about the outer heliosphere needs to be revised. Remarkably, the combination of observations of the ribbon, the belt and the globally distributed flux have provided a picture not only of the global heliosphere, but also the interstellar magnetic field, which has a strength and direction that can be directly compared to Voyager 1 observations. Currently, unraveling the interstellar magnetic field and its influences on the flows and structure of the heliosheath is an area of remarkably rapid discovery. The next quantum leap enabled by IMAP will open new windows on the frontier of Heliophysics at a time when the space environment is rapidly evolving. IMAP, like ACE before it, will be a keystone of the Heliophysics System Observatory. IMAP with 100 times the combined resolution and sensitivity of IBEX and INCA will discover the substructure of the IBEX ribbon and will reveal in unprecedented resolution global maps of our heliosphere. The remarkable synergy between IMAP, Voyager 1 and Voyager 2 will remain for at least the next decade as Voyager1 pushes further into the interstellar domain and Voyager 2 moves through the heliosheath.

  17. TeV Cosmic-Ray Anisotropy from the Magnetic Field at the Heliospheric Boundary

    Energy Technology Data Exchange (ETDEWEB)

    López-Barquero, V. [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Xu, S. [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Desiati, P. [Wisconsin IceCube Particle Astrophysics Center (WIPAC), University of Wisconsin, Madison, WI 53703 (United States); Lazarian, A. [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States); Pogorelov, N. V. [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Yan, H. [DESY, Platanenallee 6, D-15738 Zeuthen (Germany)

    2017-06-10

    We performed numerical calculations to test the suggestion by Desiati and Lazarian that the anisotropies of TeV cosmic rays may arise from their interactions with the heliosphere. For this purpose, we used a magnetic field model of the heliosphere and performed direct numerical calculations of particle trajectories. Unlike earlier papers testing the idea, we did not employ time-reversible techniques that are based on Liouville’s theorem. We showed numerically that for scattering by the heliosphere, the conditions of Liouville’s theorem are not satisfied, and the adiabatic approximation and time-reversibility of the particle trajectories are not valid. Our results indicate sensitivity to the magnetic structure of the heliospheric magnetic field, and we expect that this will be useful for probing this structure in future research.

  18. A GLOBAL TWO-TEMPERATURE CORONA AND INNER HELIOSPHERE MODEL: A COMPREHENSIVE VALIDATION STUDY

    Energy Technology Data Exchange (ETDEWEB)

    Jin, M.; Manchester, W. B.; Van der Holst, B.; Gruesbeck, J. R.; Frazin, R. A.; Landi, E.; Toth, G.; Gombosi, T. I. [Atmospheric Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Vasquez, A. M. [Instituto de Astronomia y Fisica del Espacio (CONICET-UBA) and FCEN (UBA), CC 67, Suc 28, Ciudad de Buenos Aires (Argentina); Lamy, P. L.; Llebaria, A.; Fedorov, A., E-mail: jinmeng@umich.edu [Laboratoire d' Astrophysique de Marseille, Universite de Provence, Marseille (France)

    2012-01-20

    The recent solar minimum with very low activity provides us a unique opportunity for validating solar wind models. During CR2077 (2008 November 20 through December 17), the number of sunspots was near the absolute minimum of solar cycle 23. For this solar rotation, we perform a multi-spacecraft validation study for the recently developed three-dimensional, two-temperature, Alfven-wave-driven global solar wind model (a component within the Space Weather Modeling Framework). By using in situ observations from the Solar Terrestrial Relations Observatory (STEREO) A and B, Advanced Composition Explorer (ACE), and Venus Express, we compare the observed proton state (density, temperature, and velocity) and magnetic field of the heliosphere with that predicted by the model. Near the Sun, we validate the numerical model with the electron density obtained from the solar rotational tomography of Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph C2 data in the range of 2.4 to 6 solar radii. Electron temperature and density are determined from differential emission measure tomography (DEMT) of STEREO A and B Extreme Ultraviolet Imager data in the range of 1.035 to 1.225 solar radii. The electron density and temperature derived from the Hinode/Extreme Ultraviolet Imaging Spectrometer data are also used to compare with the DEMT as well as the model output. Moreover, for the first time, we compare ionic charge states of carbon, oxygen, silicon, and iron observed in situ with the ACE/Solar Wind Ion Composition Spectrometer with those predicted by our model. The validation results suggest that most of the model outputs for CR2077 can fit the observations very well. Based on this encouraging result, we therefore expect great improvement for the future modeling of coronal mass ejections (CMEs) and CME-driven shocks.

  19. Global Fluxon Modeling of the Solar Corona and Inner Heliosphere

    Science.gov (United States)

    Lamb, D. A.; DeForest, C. E.

    2017-12-01

    The fluxon approach to MHD modeling enables simulations of low-beta plasmas in the absence of undesirable numerical effects such as diffusion and magnetic reconnection. The magnetic field can be modeled as a collection of discrete field lines ("fluxons") containing a set amount of magnetic flux in a prescribed field topology. Due to the fluxon model's pseudo-Lagrangian grid, simulations can be completed in a fraction of the time of traditional grid-based simulations, enabling near-real-time simulations of the global magnetic field structure and its influence on solar wind properties. Using SDO/HMI synoptic magnetograms as lower magnetic boundary conditions, and a separate one-dimensional fluid flow model attached to each fluxon, we compare the resulting fluxon relaxations with other commonly-used global models (such as PFSS), and with white-light images of the corona (including the August 2017 total solar eclipse). Finally, we show the computed magnetic field expansion ratio, and the modeled solar wind speed near the coronal-heliospheric transition. Development of the fluxon MHD model FLUX (the Field Line Universal relaXer), has been funded by NASA's Living with a Star program and by Southwest Research Institute.

  20. Modulation of Galactic Cosmic Rays in the Inner Heliosphere, Comparing with PAMELA Measurements

    Science.gov (United States)

    Qin, G.; Shen, Z.-N.

    2017-09-01

    We develop a numerical model to study the time-dependent modulation of galactic cosmic rays in the inner heliosphere. In the model, a time-delayed modified Parker heliospheric magnetic field (HMF) and a new diffusion coefficient model, NLGCE-F, from Qin & Zhang, are adopted. In addition, the latitudinal dependence of magnetic turbulence magnitude is assumed to be ˜ (1+{\\sin }2θ )/2 from the observations of Ulysses, and the radial dependence is assumed to be ˜ {r}S, where we choose an expression of S as a function of the heliospheric current sheet tilt angle. We show that the analytical expression used to describe the spatial variation of HMF turbulence magnitude agrees well with the Ulysses, Voyager 1, and Voyager 2 observations. By numerically calculating the modulation code, we get the proton energy spectra as a function of time during the recent solar minimum, it is shown that the modulation results are consistent with the Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics measurements.

  1. From the Outside Looking In - Looking Back at Our Heliosphere in Energetic Neutral Atoms

    Science.gov (United States)

    Demajistre, R.; Brandt, P. C.; Gruntman, M.; McNutt, R. L., Jr.; Opher, M.; Roelof, E. C.; Wood, B. E.

    2017-12-01

    Energetic Neutral Atoms (ENAs) have been used over the past two decades to image space plasmas in planetary magnetospheres as well as the structure of the heliosheath. Any energetic plasma containing singly charged ions embedded in a cold neutral gas will 'glow' in ENAs, and this glow can be analyzed to infer the properties of the source plasma, giving us insight into processes that are difficult to study with the more traditional sensors that use photons/electromagnetic waves as an information carrier. ENA measurements of the heliosphere have (obviously) all been taken from vantage points in the inner heliosphere. ENAs created in the inner heliosphere from the solar wind and Pick Up Ions (PUIs) generally have large outward velocity, and thus do not reach sensors closer to the sun. Thus, the plasma is only 'visible' in ENAs to an inner heliosphere observer after it reaches the termination shock, where its outward motion is slowed and it is heated. This perspective from the inside looking out is convenient to study the outer boundary of the heliophere, but contains no direct information about the plasma and processes occurring in the inner heliosphere. ENA sensors placed outside the heliosphere, conversely would allow us to remotely sense both the inner and outer heliosphere, allowing us full access to the evolution of the solar wind and PUIs as they travel from the sun outward. Further, such a perspective would allow us to more directly measure the boundaries of the heliosphere with the LISM without the obscuration of the inner heliosheath. In this paper, we present modeled views of ENA images from the outside looking in at energies between 0.5 and 100 keV. It is important to note that while measurements of the outer heliosphere have been made by IBEX, Cassini/INCA, SoHO/HSTOF and the Voyagers, there are still important outstanding questions about the global structure and plasma flow patterns in the heliosphere. We will show here how new observations from the

  2. Ulysses Data Analysis: Magnetic Topology of Heliospheric Structures

    Science.gov (United States)

    Crooker, Nancy

    2001-01-01

    In this final technical report on research funded by a NASA grant, a project overview is given by way of summaries on nine published papers. Research has included: 1) Using suprathermal electron data to study heliospheric magnetic structures; 2) Analysis of magnetic clouds, coronal mass ejections (CME), and the heliospheric current sheet (HCS); 3) Analysis of the corotating interaction region (CIR) which develop from interactions between solar wind streams of different velocities; 4) Use of Ulysses data in the interpretation of heliospheric events and phenomena.

  3. ENERGETIC NEUTRAL ATOMS: AN ADDITIONAL SOURCE FOR HELIOSPHERIC PICKUP IONS

    International Nuclear Information System (INIS)

    Bochsler, Peter; Moebius, Eberhard

    2010-01-01

    Recently, Schwadron and McComas discussed the possibility of inner source pickup particles originating from the ionization of energetic neutral atoms (ENAs), based on new data from the IBEX mission. This proposition has some interesting features, namely, it might be able to explain why inner source pickup ions (PUIs) have a composition resembling solar abundances and show no indication of overabundance of refractory elements, although this should be expected, if the conventional explanation of solar wind-dust interaction for the origin of this heliospheric component were correct. In this Letter, we explore further consequences for ENA-related PUIs and investigate their velocity distributions. We conclude that this model will not reproduce the observed velocity distributions of inner source PUIs and point out a substantial deviation in their composition. However, it seems likely that the ionization of ENAs as observed with IBEX could contribute a significant amount of heliospheric suprathermal tail ions. Some possible consequences of our investigation for heliospheric particle populations are briefly discussed.

  4. Breathing of heliospheric structures triggered by the solar-cycle activity

    Directory of Open Access Journals (Sweden)

    K. Scherer

    Full Text Available Solar wind ram pressure variations occuring within the solar activity cycle are communicated to the outer heliosphere as complicated time-variabilities, but repeating its typical form with the activity period of about 11 years. At outer heliospheric regions, the main surviving solar cycle feature is a periodic variation of the solar wind dynamical pressure or momentum flow, as clearly recognized by observations of the VOYAGER-1/2 space probes. This long-periodic variation of the solar wind dynamical pressure is modeled here through application of appropriately time-dependent inner boundary conditions within our multifluid code to describe the solar wind – interstellar medium interaction. As we can show, it takes several solar cycles until the heliospheric structures adapt to an average location about which they carry out a periodic breathing, however, lagged in phase with respect to the solar cycle. The dynamically active heliosphere behaves differently from a static heliosphere and especially shows a historic hysteresis in the sense that the shock structures move out to larger distances than explained by the average ram pressure. Obviously, additional energies are pumped into the heliosheath by means of density and pressure waves which are excited. These waves travel outwards through the interface from the termination shock towards the bow shock. Depending on longitude, the heliospheric sheath region memorizes 2–3 (upwind and up to 6–7 (downwind preceding solar activity cycles, i.e. the cycle-induced waves need corresponding travel times for the passage over the heliosheath. Within our multifluid code we also adequately describe the solar cycle variations in the energy distributions of anomalous and galactic cosmic rays, respectively. According to these results the distribution of these high energetic species cannot be correctly described on the basis of the actually prevailing solar wind conditions.

    Key words. Interplanetary

  5. Solar wind stream interaction regions throughout the heliosphere

    Science.gov (United States)

    Richardson, Ian G.

    2018-01-01

    This paper focuses on the interactions between the fast solar wind from coronal holes and the intervening slower solar wind, leading to the creation of stream interaction regions that corotate with the Sun and may persist for many solar rotations. Stream interaction regions have been observed near 1 AU, in the inner heliosphere (at ˜ 0.3-1 AU) by the Helios spacecraft, in the outer and distant heliosphere by the Pioneer 10 and 11 and Voyager 1 and 2 spacecraft, and out of the ecliptic by Ulysses, and these observations are reviewed. Stream interaction regions accelerate energetic particles, modulate the intensity of Galactic cosmic rays and generate enhanced geomagnetic activity. The remote detection of interaction regions using interplanetary scintillation and white-light imaging, and MHD modeling of interaction regions will also be discussed.

  6. Modeling Solar Energetic Particle Transport near a Wavy Heliospheric Current Sheet

    Science.gov (United States)

    Battarbee, Markus; Dalla, Silvia; Marsh, Mike S.

    2018-02-01

    Understanding the transport of solar energetic particles (SEPs) from acceleration sites at the Sun into interplanetary space and to the Earth is an important question for forecasting space weather. The interplanetary magnetic field (IMF), with two distinct polarities and a complex structure, governs energetic particle transport and drifts. We analyze for the first time the effect of a wavy heliospheric current sheet (HCS) on the propagation of SEPs. We inject protons close to the Sun and propagate them by integrating fully 3D trajectories within the inner heliosphere in the presence of weak scattering. We model the HCS position using fits based on neutral lines of magnetic field source surface maps (SSMs). We map 1 au proton crossings, which show efficient transport in longitude via HCS, depending on the location of the injection region with respect to the HCS. For HCS tilt angles around 30°–40°, we find significant qualitative differences between A+ and A‑ configurations of the IMF, with stronger fluences along the HCS in the former case but with a distribution of particles across a wider range of longitudes and latitudes in the latter. We show how a wavy current sheet leads to longitudinally periodic enhancements in particle fluence. We show that for an A+ IMF configuration, a wavy HCS allows for more proton deceleration than a flat HCS. We find that A‑ IMF configurations result in larger average fluences than A+ IMF configurations, due to a radial drift component at the current sheet.

  7. Validation of community models: 3. Tracing field lines in heliospheric models

    Science.gov (United States)

    MacNeice, Peter; Elliott, Brian; Acebal, Ariel

    2011-10-01

    Forecasting hazardous gradual solar energetic particle (SEP) bursts at Earth requires accurately modeling field line connections between Earth and the locations of coronal or interplanetary shocks that accelerate the particles. We test the accuracy of field lines reconstructed using four different models of the ambient coronal and inner heliospheric magnetic field, through which these shocks must propagate, including the coupled Wang-Sheeley-Arge (WSA)/ENLIL model. Evaluating the WSA/ENLIL model performance is important since it is the most sophisticated model currently available to space weather forecasters which can model interplanetary coronal mass ejections and, when coupled with particle acceleration and transport models, will provide a complete model for gradual SEP bursts. Previous studies using a simpler Archimedean spiral approach above 2.5 solar radii have reported poor performance. We test the accuracy of the model field lines connecting Earth to the Sun at the onset times of 15 impulsive SEP bursts, comparing the foot points of these field lines with the locations of surface events believed to be responsible for the SEP bursts. We find the WSA/ENLIL model performance is no better than the simplest spiral model, and the principal source of error is the model's inability to reproduce sufficient low-latitude open flux. This may be due to the model's use of static synoptic magnetograms, which fail to account for transient activity in the low corona, during which reconnection events believed to initiate the SEP acceleration may contribute short-lived open flux at low latitudes. Time-dependent coronal models incorporating these transient events may be needed to significantly improve Earth/Sun field line forecasting.

  8. INTERSTELLAR NEUTRAL HELIUM IN THE HELIOSPHERE FROM IBEX OBSERVATIONS. II. THE WARSAW TEST PARTICLE MODEL (WTPM)

    Energy Technology Data Exchange (ETDEWEB)

    Sokół, J. M.; Kubiak, M. A.; Bzowski, M.; Swaczyna, P., E-mail: jsokol@cbk.waw.pl [Space Research Centre of the Polish Academy of Sciences, 00-716 Warsaw (Poland)

    2015-10-15

    We have developed a refined and optimized version of the Warsaw Test Particle Model of interstellar neutral gas in the heliosphere, specially tailored for analysis of IBEX-Lo observations. The former version of the model was used in the analysis of neutral He observed by IBEX that resulted in an unexpected conclusion that the interstellar neutral He flow vector was different than previously thought and that a new population of neutral He, dubbed the Warm Breeze, exists in the heliosphere. It was also used in the reanalysis of Ulysses observations that confirmed the original findings on the flow vector, but suggested a significantly higher temperature. The present version of the model has two strains targeted for different applications, based on an identical paradigm, but differing in the implementation and in the treatment of ionization losses. We present the model in detail and discuss numerous effects related to the measurement process that potentially modify the resulting flux of ISN He observed by IBEX, and identify those of them that should not be omitted in the simulations to avoid biasing the results. This paper is part of a coordinated series of papers presenting the current state of analysis of IBEX-Lo observations of ISN He. Details of the analysis method are presented by Swaczyna et al. and results of the analysis are presented by Bzowski et al.

  9. Energetic particles in the heliosphere

    CERN Document Server

    Simnett, George M

    2017-01-01

    This monograph traces the development of our understanding of how and where energetic particles are accelerated in the heliosphere and how they may reach the Earth. Detailed data sets are presented which address these topics. The bulk of the observations are from spacecraft in or near the ecliptic plane. It is timely to present this subject now that Voyager-1 has entered the true interstellar medium. Since it seems unlikely that there will be a follow-on to the Voyager programme any time soon, the data we already have regarding the outer heliosphere are not going to be enhanced for at least 40 years.

  10. POSSIBLE EVIDENCE FOR A FISK-TYPE HELIOSPHERIC MAGNETIC FIELD. I. ANALYZING ULYSSES/KET ELECTRON OBSERVATIONS

    International Nuclear Information System (INIS)

    Sternal, O.; Heber, B.; Kopp, A.; Engelbrecht, N. E.; Burger, R. A.; Ferreira, S. E. S.; Potgieter, M. S.; Fichtner, H.; Scherer, K.

    2011-01-01

    The propagation of energetic charged particles in the heliospheric magnetic field is one of the fundamental problems in heliophysics. In particular, the structure of the heliospheric magnetic field remains an unsolved problem and is discussed as a controversial topic. The first successful analytic approach to the structure of the heliospheric magnetic field was the Parker field. However, the measurements of the Ulysses spacecraft at high latitudes revealed the possible need for refinements of the existing magnetic field model during solar minimum. Among other reasons, this led to the development of the Fisk field. This approach is highly debated and could not be ruled out with magnetic field measurements so far. A promising method to trace this magnetic field structure is to model the propagation of electrons in the energy range of a few MeV. Employing three-dimensional and time-dependent simulations of the propagation of energetic electrons, this work shows that the influence of a Fisk-type field on the particle transport in the heliosphere leads to characteristic variations of the electron intensities on the timescale of a solar rotation. For the first time it is shown that the Ulysses count rates of 2.5-7 MeV electrons contain the imprint of a Fisk-type heliospheric magnetic field structure. From a comparison of simulation results and the Ulysses count rates, realistic parameters for the Fisk theory are derived. Furthermore, these parameters are used to investigate the modeled relative amplitudes of protons and electrons, including the effects of drifts.

  11. Validation for Global Solar Wind Prediction Using Ulysses Comparison: Multiple Coronal and Heliospheric Models Installed at the Community Coordinated Modeling Center

    Science.gov (United States)

    Jian, L. K.; MacNeice, P. J.; Mays, M. L.; Taktakishvili, A.; Odstrcil, D.; Jackson, B.; Yu, H.-S.; Riley, P.; Sokolov, I. V.

    2016-01-01

    The prediction of the background global solar wind is a necessary part of space weather forecasting. Several coronal and heliospheric models have been installed and/or recently upgraded at the Community Coordinated Modeling Center (CCMC), including the Wang-Sheely-Arge (WSA)-Enlil model, MHD-Around-a-Sphere (MAS)-Enlil model, Space Weather Modeling Framework (SWMF), and Heliospheric tomography using interplanetary scintillation data. Ulysses recorded the last fast latitudinal scan from southern to northern poles in 2007. By comparing the modeling results with Ulysses observations over seven Carrington rotations, we have extended our third-party validation from the previous near-Earth solar wind to middle to high latitudes, in the same late declining phase of solar cycle 23. Besides visual comparison, wehave quantitatively assessed the models capabilities in reproducing the time series, statistics, and latitudinal variations of solar wind parameters for a specific range of model parameter settings, inputs, and grid configurations available at CCMC. The WSA-Enlil model results vary with three different magnetogram inputs.The MAS-Enlil model captures the solar wind parameters well, despite its underestimation of the speed at middle to high latitudes. The new version of SWMF misses many solar wind variations probably because it uses lower grid resolution than other models. The interplanetary scintillation-tomography cannot capture the latitudinal variations of solar wind well yet. Because the model performance varies with parameter settings which are optimized for different epochs or flow states, the performance metric study provided here can serve as a template that researchers can use to validate the models for the time periods and conditions of interest to them.

  12. Validation for global solar wind prediction using Ulysses comparison: Multiple coronal and heliospheric models installed at the Community Coordinated Modeling Center

    Science.gov (United States)

    Jian, L. K.; MacNeice, P. J.; Mays, M. L.; Taktakishvili, A.; Odstrcil, D.; Jackson, B.; Yu, H.-S.; Riley, P.; Sokolov, I. V.

    2016-08-01

    The prediction of the background global solar wind is a necessary part of space weather forecasting. Several coronal and heliospheric models have been installed and/or recently upgraded at the Community Coordinated Modeling Center (CCMC), including the Wang-Sheely-Arge (WSA)-Enlil model, MHD-Around-a-Sphere (MAS)-Enlil model, Space Weather Modeling Framework (SWMF), and heliospheric tomography using interplanetary scintillation data. Ulysses recorded the last fast latitudinal scan from southern to northern poles in 2007. By comparing the modeling results with Ulysses observations over seven Carrington rotations, we have extended our third-party validation from the previous near-Earth solar wind to middle to high latitudes, in the same late declining phase of solar cycle 23. Besides visual comparison, we have quantitatively assessed the models' capabilities in reproducing the time series, statistics, and latitudinal variations of solar wind parameters for a specific range of model parameter settings, inputs, and grid configurations available at CCMC. The WSA-Enlil model results vary with three different magnetogram inputs. The MAS-Enlil model captures the solar wind parameters well, despite its underestimation of the speed at middle to high latitudes. The new version of SWMF misses many solar wind variations probably because it uses lower grid resolution than other models. The interplanetary scintillation-tomography cannot capture the latitudinal variations of solar wind well yet. Because the model performance varies with parameter settings which are optimized for different epochs or flow states, the performance metric study provided here can serve as a template that researchers can use to validate the models for the time periods and conditions of interest to them.

  13. [A Predictive Model for the Magnetic Field in the Heliosphere and Acceleration of Suprathermal Particles in the Solar Wind

    Science.gov (United States)

    Fisk, L. A.

    2005-01-01

    The purpose of this grant was to develop a theoretical understanding of the processes by which open magnetic flux undergoes large-scale transport in the solar corona, and to use this understanding to develop a predictive model for the heliospheric magnetic field, the configuration for which is determined by such motions.

  14. MICROSTRUCTURE OF THE HELIOSPHERIC TERMINATION SHOCK: IMPLICATIONS FOR ENERGETIC NEUTRAL ATOM OBSERVATIONS

    International Nuclear Information System (INIS)

    Zank, G. P.; Heerikhuisen, J.; Pogorelov, N. V.; Burrows, R.; McComas, D.

    2010-01-01

    The Voyager 2 plasma observations of the proton distribution function downstream of the quasi-perpendicular heliospheric termination shock (TS) showed that upstream thermal solar wind ions played little role in the shock dissipation mechanism, being essentially transmitted directly through the shock. Instead, the hot supra-thermal pickup ion (PUI) component is most likely responsible for the dissipation at the TS. Consequently, the downstream proton distribution function will be a complicated superposition of relatively cool thermal solar wind protons and hot PUIs that have experienced either direct transmission or reflection at the TS cross-shock potential. We develop a simple model for the TS microstructure that allows us to construct approximate proton distribution functions for the inner heliosheath. The distribution function models are compared to κ-distributions, showing the correspondence between the two. Since the interpretation of energetic neutral atom (ENA) fluxes measured at 1 AU by IBEX will depend sensitively on the form of the underlying proton distribution function, we use a three-dimensional MHD-kinetic global model to model ENA spectra at 1 AU and ENA skymaps across the IBEX energy range. We consider both solar minimum and solar maximum-like global models, showing how ENA skymap structure can be related to global heliospheric structure. We suggest that the ENA spectra may allow us to probe the directly the microphysics of the TS, while the ENA skymaps reveal heliospheric structure and, at certain energies, are distinctly different during solar minimum and maximum.

  15. Three-dimensional Features of the Outer Heliosphere Due to Coupling between the Interstellar and Heliospheric Magnetic Field. V. The Bow Wave, Heliospheric Boundary Layer, Instabilities, and Magnetic Reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Pogorelov, N. V.; Heerikhuisen, J. [Department of Space Science, The University of Alabama in Huntsville, AL 35805 (United States); Roytershteyn, V. [Space Science Institute, Boulder, CO 80301 (United States); Burlaga, L. F. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gurnett, D. A.; Kurth, W. S., E-mail: nikolai.pogorelov@uah.edu [Department of Physics and Astronomy, The University of Iowa, Iowa City, IA 52242 (United States)

    2017-08-10

    The heliosphere is formed due to interaction between the solar wind (SW) and local interstellar medium (LISM). The shape and position of the heliospheric boundary, the heliopause, in space depend on the parameters of interacting plasma flows. The interplay between the asymmetrizing effect of the interstellar magnetic field and charge exchange between ions and neutral atoms plays an important role in the SW–LISM interaction. By performing three-dimensional, MHD plasma/kinetic neutral atom simulations, we determine the width of the outer heliosheath—the LISM plasma region affected by the presence of the heliosphere—and analyze quantitatively the distributions in front of the heliopause. It is shown that charge exchange modifies the LISM plasma to such extent that the contribution of a shock transition to the total variation of plasma parameters becomes small even if the LISM velocity exceeds the fast magnetosonic speed in the unperturbed medium. By performing adaptive mesh refinement simulations, we show that a distinct boundary layer of decreased plasma density and enhanced magnetic field should be observed on the interstellar side of the heliopause. We show that this behavior is in agreement with the plasma oscillations of increasing frequency observed by the plasma wave instrument onboard Voyager 1. We also demonstrate that Voyager observations in the inner heliosheath between the heliospheric termination shock and the heliopause are consistent with dissipation of the heliospheric magnetic field. The choice of LISM parameters in this analysis is based on the simulations that fit observations of energetic neutral atoms performed by Interstellar Boundary Explorer .

  16. A MEASUREMENT OF THE ADIABATIC COOLING INDEX FOR INTERSTELLAR HELIUM PICKUP IONS IN THE INNER HELIOSPHERE

    International Nuclear Information System (INIS)

    Saul, Lukas; Wurz, Peter; Kallenbach, Reinald

    2009-01-01

    Interstellar neutral gas enters the inner heliosphere where it is ionized and becomes the pickup ion population of the solar wind. It is often assumed that this population will subsequently cool adiabatically, like an expanding ideal gas due, to the divergent flow of the solar wind. Here, we report the first independent measure of the effective adiabatic cooling index in the inner heliosphere from SOHO CELIAS measurements of singly charged helium taken during times of perpendicular interplanetary magnetic field. We use a simple adiabatic transport model of interstellar pickup helium ions, valid for the upwind region of the inner heliosphere. The time averaged velocity spectrum of helium pickup ions measured by CELIAS/CTOF is fit to this model with a single free parameter which indicates an effective cooling rate with a power-law index of γ = 1.35 ± 0.2. While this average is consistent with the 'ideal-gas' assumption of γ = 1.5, the analysis indicates that such an assumption will not apply in general, and that due to observational constraints further measurements are necessary to constrain the cooling process. Implications are discussed for understanding the transport processes in the inner heliosphere and improving this measurement technique.

  17. The Sun and Heliosphere Explorer – The Interhelioprobe Mission

    Czech Academy of Sciences Publication Activity Database

    Kuznetsov, V. D.; Zimovets, I.V.; Anufreychik, K.; Bezrukikh, V.; Chulkov, I. V.; Konovalov, A. A.; Kotova, G.A.; Kovrazhkin, R. A.; Moiseenko, D.; Petrukovich, A. A.; Remizov, A.; Shestakov, A.; Skalsky, A.; Vaisberg, O. L.; Verigin, M. I.; Zhuravlev, R. N.; Andreevskyi, S. E.; Dokukin, V. S.; Fomichev, V. V.; Lebedev, N. I.; Obridko, V. N.; Polyanskyi, V. P.; Styazhkin, V. A.; Rudenchik, E. A.; Sinelnikov, V. M.; Zhugzhda, Yu. D.; Ryzhenko, A. P.; Ivanov, A. V.; Simonov, A. V.; Dobrovolskyi, V. S.; Konstantinov, M. S.; Kuzin, S. V.; Bogachev, S. A.; Kholodilov, A. A.; Kirichenko, A. S.; Lavrentiev, E. N.; Reva, A. A.; Shestov, S. V.; Ulyanov, A. S.; Panasyuk, M. I.; Iyudin, A. F.; Svertilov, S. I.; Bogomolov, V. V.; Galkin, V. I.; Marjin, B. V.; Morozov, O. V.; Osedlo, V. I.; Rubinshtein, I. A.; Scherbovsky, B. Ya.; Tulupov, V. I.; Kotov, Yu. D.; Yurov, V. N.; Glyanenko, A. S.; Kochemasov, A. V.; Lupar, E. E.; Rubtsov, I. V.; Trofimov, Yu. A.; Tyshkevich, V. G.; Ulin, S. E.; Novikov, A. S.; Dmitrenko, V. V.; Grachev, V. M.; Stekhanov, V. N.; Vlasik, K. F.; Uteshev, Z. M.; Chernysheva, I. V.; Shustov, A. E.; Petrenko, D. V.; Aptekar, R. L.; Dergachev, V. A.; Golenetskii, S. V.; Gribovskyi, K. S.; Frederiks, D. D.; Kruglov, E. M.; Lazutkov, V. P.; Levedev, V. V.; Oleinik, F. P.; Palshin, V. D.; Repin, A. I.; Savchenko, M. I.; Skorodumov, D. V.; Svinkin, D. S.; Tsvetkova, A. S.; Ulanov, M. V.; Kozhevatov, I. E.; Sylwester, J.; Siarkowski, M.; Bąkała, J.; Szaforz, Ż.; Kowaliński, M.; Dudnik, O. V.; Lavraud, B.; Hruška, František; Kolmašová, Ivana; Santolík, Ondřej; Šimůnek, Jiří; Truhlík, Vladimír; Auster, H.-U.; Hilchenbach, M.; Venedictov, Yu.; Berghofer, G.

    2016-01-01

    Roč. 56, č. 7 (2016), s. 781-841 ISSN 0016-7932 Institutional support: RVO:68378289 Keywords : Sun * heliosphere * Interhelioprobe space mission * solar physics * heliospheric physics * solar-terrestrial relations Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.482, year: 2016 http://link.springer.com/article/10.1134/S0016793216070124

  18. Heliospheric Modulation Strength During The Neutron Monitor Era

    Science.gov (United States)

    Usoskin, I. G.; Alanko, K.; Mursula, K.; Kovaltsov, G. A.

    Using a stochastic simulation of a one-dimensional heliosphere we calculate galactic cosmic ray spectra at the Earth's orbit for different values of the heliospheric mod- ulation strength. Convoluting these spectra with the specific yield function of a neu- tron monitor, we obtain the expected neutron monitor count rates for different values of the modulation strength. Finally, inverting this relation, we calculate the modula- tion strength using the actually recorded neutron monitor count rates. We present the reconstructed annual heliospheric modulation strengths for the neutron monitor era (1953­2000) using several neutron monitors from different latitudes, covering a large range of geomagnetic rigidity cutoffs from polar to equatorial regions. The estimated modulation strengths are shown to be in good agreement with the corresponding esti- mates reported earlier for some years.

  19. SOLAR PHOTOIONIZATION RATES FOR INTERSTELLAR NEUTRALS IN THE INNER HELIOSPHERE: H, He, O, AND Ne

    Energy Technology Data Exchange (ETDEWEB)

    Bochsler, P.; Kucharek, H.; Möbius, E. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States); Bzowski, Maciej; Sokół, Justyna M. [Space Research Center of the Polish Academy of Sciences, Ul. Bartycka 18A, 00-716 Warsaw (Poland); Didkovsky, Leonid; Wieman, Seth, E-mail: bochsler@space.unibe.ch [Space Sciences Center, University of Southern California, Los Angeles, CA 90089-1341 (United States)

    2014-01-01

    Extreme UV (EUV) spectra from the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED)/Solar EUV Experiment are used to infer photoionization rates in the inner heliosphere. Relating these rates to various proxies describing the solar EUV radiation, we construct a multi-linear model which allows us to extrapolate ionization rates back to periods when no routine measurements of the solar EUV spectral distribution have been available. Such information is important, e.g., for comparing conditions of the interstellar neutral particles in the inner heliosphere at the time of Ulysses/GAS observations with conditions during the more recent observations of the Interstellar Boundary Explorer. From a period of 11 yr when detailed spectra from both TIMED and three proxies—Solar and Heliospheric Observatory/CELIAS/SEM-rates, F10.7 radio flux, and Mg II core-to-wing indices—have been available, we conclude that the simple model is able to reproduce the photoionization rates with an uncertainty of typically 5%.

  20. The Heliospheric Termination Shock

    Science.gov (United States)

    Jokipii, J. R.

    2013-06-01

    The heliospheric termination shock is a vast, spheroidal shock wave marking the transition from the supersonic solar wind to the slower flow in the heliosheath, in response to the pressure of the interstellar medium. It is one of the most-important boundaries in the outer heliosphere. It affects energetic particles strongly and for this reason is a significant factor in the effects of the Sun on Galactic cosmic rays. This paper summarizes the general properties and overall large-scale structure and motions of the termination shock. Observations over the past several years, both in situ and remote, have dramatically revised our understanding of the shock. The consensus now is that the shock is quite blunt, is with the front, blunt side canted at an angle to the flow direction of the local interstellar plasma relative to the Sun, and is dynamical and turbulent. Much of this new understanding has come from remote observations of energetic charged particles interacting with the shock, radio waves and radiation backscattered from interstellar neutral atoms. The observations and the implications are discussed.

  1. INTERSTELLAR PICKUP ION PRODUCTION IN THE GLOBAL HELIOSPHERE AND HELIOSHEATH

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.; Florinski, V.; Guo, X., E-mail: yw0009@uah.edu [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35805 (United States)

    2016-11-20

    Interstellar pickup ions (PUIs) play a significant part in mediating the solar wind (SW) interaction with the interstellar medium. In this paper, we examine the details of spatial variation of the PUI velocity distribution function (VDF) in the SW by solving the PUI transport equation. We assume the PUI distribution is isotropic resulting from strong pitch-angle scattering by wave–particle interaction. A three-dimensional model combining the MHD treatment of the background SW and neutrals with a kinetic treatment of PUIs throughout the heliosphere and the surrounding local interstellar medium has been developed. The model generates PUI power-law tails via second-order Fermi process. We analyze how PUIs transform across the heliospheric termination shock and obtain the PUI phase space distribution in the inner heliosheath including continuing velocity diffusion. Our simulated PUI spectra are compared with observations made by New Horizons , Ulysses , Voyager 1, 2 , and Cassini , and a satisfactory agreement is demonstrated. Some specific features in the observations, for example, a cutoff of PUI VDF at v = V {sub SW} and a f ∝ v {sup -5} tail in the reference frame of the SW, are well represented by the model.

  2. Energetic particles beyond the heliospheric shock: Anomalous Cosmic Rays (ACRs), Pick-Up Ions (PUIs) and the associated energetic neutral atoms (ENAs)

    International Nuclear Information System (INIS)

    Fichtner, Horst; Czechowski, Andrzej; Fahr, Hans J.; Lay, Guenter

    2000-01-01

    The Voyager 1 spacecraft is expected to encounter the heliospheric termination shock within the next decade. Besides the ongoing discussion how to possibly predict the time of this encounter, there is a growing interest into a more detailed description of the region beyond the heliospheric shock, i.e., the heliosheath. Refinements of the so far rather crude models will facilitate interpretation of forthcoming data. We report on results obtained with our model of the transport of ACRs in the heliosheath. In improvement of earlier approaches it is based on a solar wind background flow computed with a self-consistent large-scale model of the heliosphere. Besides these downstream ACR spectra, which will become accessible for in situ observation as soon as the Voyager spacecraft will have crossed the heliospheric shock, we study the potential of observations of the flux of ENAs to remotely explore the structure of the heliosheath. In particular, as part of a comparison of the various ENA sources, we will address the significance of the contribution of those ENAs resulting from a de-charging of PUIs

  3. FEASIBILITY OF HELIOSPHERIC IMAGING FROM NEAR EARTH

    International Nuclear Information System (INIS)

    DeForest, C. E.; Howard, T. A.

    2015-01-01

    Imaging solar wind structures via Thomson scattered sunlight has proved important to understanding the inner heliosphere. The principal challenge of heliospheric imaging is background subtraction: typical solar wind features are fainter than the zodiacal light and starfield by 2-3 orders of magnitude. Careful post-processing is required to separate the solar wind signal from the static background. Remnant background, and not photon noise, is the dominant noise source in current STEREO data. We demonstrate that 10× shorter exposure times would not strongly affect the noise level in these data. Further, we demonstrate that current processing techniques are sufficient to separate not only the existing background of the STEREO images but also diffuse variable backgrounds such as are expected to be seen from low Earth orbit. We report on a hare-and-hounds style study, demonstrating blind signal extraction from STEREO/HI-2 data that have been degraded by the addition of large-scale, time-dependent artifacts to simulate viewing through airglow or high-altitude aurora. We demonstrate removal of these effects via image processing, with little degradation compared to the original. Even with as few as three highly degraded source images over 48 hr, it is possible to detect and track large coronal mass ejections more than 40° from the Sun. This implies that neither the high altitude aurora discovered by Coriolis/SMEI, nor airglow effects seen from low Earth orbit, are impediments to a hypothetical next-generation heliospheric imager in low Earth orbit; and also that post-processing is as important to heliospheric image qualitiy as are optical contamination effects

  4. Energetic Particles: From Sun to Heliosphere - and vice versa

    Science.gov (United States)

    Wimmer-Schweingruber, R. F.; Rodriguez-Pacheco, J.; Boden, S.; Boettcher, S. I.; Cernuda, I.; Dresing, N.; Drews, C.; Droege, W.; Espinosa Lara, F.; Gomez-Herrero, R.; Heber, B.; Ho, G. C.; Klassen, A.; Kulkarni, S. R.; Mann, G. J.; Martin-Garcia, C.; Mason, G. M.; Panitzsch, L.; Prieto, M.; Sanchez, S.; Terasa, C.; Eldrum, S.

    2017-12-01

    Energetic particles in the heliosphere can be measured at their elevated energetic status after three processes: injection, acceleration, and transport. Suprathermal seed particles have speeds well above the fast magnetosonic speed in the solar wind frame of reference and can vary from location to location and within the solar activity cycle. Acceleration sites include reconnecting current sheets in solar flares or magnetspheric boundaries, shocks in the solar corona, heliosphere and a planetary obstacles, as well as planetary magnetospheres. Once accelerated, particles are transported from the acceleration site into and through the heliosphere. Thus, by investigating properties of energetic particles such as their composition, energy spectra, pitch-angle distribution, etc. one can attempt to distinguish their origin or injection and acceleration site. This in turn allows us to better understand transport effects whose underlying microphysics is also a key ingredient in the acceleration of particles. In this presentation we will present some clear examples which link energetic particles from their observing site to their source locations. These include Jupiter electrons, singly-charged He ions from CIRs, and 3He from solar flares. We will compare these examples with the measurement capabilities of the Energetic Particle Detector (EPD) on Solar Orbiter and consider implications for the key science goal of Solar Orbiter and Solar Proble Plus - How the Sun creates and controls the heliosphere.

  5. Solar Energetic Particle Transport Near a Heliospheric Current Sheet

    Energy Technology Data Exchange (ETDEWEB)

    Battarbee, Markus; Dalla, Silvia [Jeremiah Horrocks Institute, University of Central Lancashire, PR1 2HE (United Kingdom); Marsh, Mike S., E-mail: mbattarbee@uclan.ac.uk [Met Office, Exeter, EX1 3 PB (United Kingdom)

    2017-02-10

    Solar energetic particles (SEPs), a major component of space weather, propagate through the interplanetary medium strongly guided by the interplanetary magnetic field (IMF). In this work, we analyze the implications that a flat Heliospheric Current Sheet (HCS) has on proton propagation from SEP release sites to the Earth. We simulate proton propagation by integrating fully 3D trajectories near an analytically defined flat current sheet, collecting comprehensive statistics into histograms, fluence maps, and virtual observer time profiles within an energy range of 1–800 MeV. We show that protons experience significant current sheet drift to distant longitudes, causing time profiles to exhibit multiple components, which are a potential source of confusing interpretations of observations. We find that variation of the current sheet thickness within a realistic parameter range has little effect on particle propagation. We show that the IMF configuration strongly affects the deceleration of protons. We show that in our model, the presence of a flat equatorial HCS in the inner heliosphere limits the crossing of protons into the opposite hemisphere.

  6. WARM BREEZE FROM THE STARBOARD BOW: A NEW POPULATION OF NEUTRAL HELIUM IN THE HELIOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Kubiak, M. A.; Bzowski, M.; Sokół, J. M.; Swaczyna, P.; Grzedzielski, S. [Space Research Centre of the Polish Academy of Sciences, Warsaw (Poland); Alexashov, D. B.; Izmodenov, V. V. [Space Research Institute (IKI) of the Russian Academy of Sciences, Moscow (Russian Federation); Möbius, E.; Leonard, T. [Space Research Center and Department of Physics, University of New Hampshire, Durham, NH (United States); Fuselier, S. A.; McComas, D. J. [Southwest Research Institute, San Antonio, TX (United States); Wurz, P. [Physics Institute, University of Bern, Bern (Switzerland)

    2014-08-01

    We investigate the signals from neutral helium atoms observed in situ from Earth orbit in 2010 by the Interstellar Boundary Explorer (IBEX). The full helium signal observed during the 2010 observation season can be explained as a superposition of pristine neutral interstellar He gas and an additional population of neutral helium that we call the Warm Breeze. The Warm Breeze is approximately 2 times slower and 2.5 times warmer than the primary interstellar He population, and its density in front of the heliosphere is ∼7% that of the neutral interstellar helium. The inflow direction of the Warm Breeze differs by ∼19° from the inflow direction of interstellar gas. The Warm Breeze seems to be a long-term, perhaps permanent feature of the heliospheric environment. It has not been detected earlier because it is strongly ionized inside the heliosphere. This effect brings it below the threshold of detection via pickup ion and heliospheric backscatter glow observations, as well as by the direct sampling of GAS/Ulysses. We discuss possible sources for the Warm Breeze, including (1) the secondary population of interstellar helium, created via charge exchange and perhaps elastic scattering of neutral interstellar He atoms on interstellar He{sup +} ions in the outer heliosheath, or (2) a gust of interstellar He originating from a hypothetic wave train in the Local Interstellar Cloud. A secondary population is expected from models, but the characteristics of the Warm Breeze do not fully conform to modeling results. If, nevertheless, this is the explanation, IBEX-Lo observations of the Warm Breeze provide key insights into the physical state of plasma in the outer heliosheath. If the second hypothesis is true, the source is likely to be located within a few thousand AU from the Sun, which is the propagation range of possible gusts of interstellar neutral helium with the Warm Breeze characteristics against dissipation via elastic scattering in the Local Cloud. Whatever the

  7. Modulation of galactic and anomalous cosmic rays in the inner heliosphere

    Science.gov (United States)

    Heber, B.

    Our knowledge on how galactic and anomalous cosmic rays are modulated in the inner heliosphere has been dramatically enlarged due to measurements provided by several missions launched in the past ten years. The current paradigma of singly charged anomalous cosmic rays has been confirmed by recent measurements from the SAMPEX and ACE satelite. Ulysses explored the inner heliosphere at polar regions during the last solar minimum period and is heading again to high heliographic latitudes during the time of the conference in July, 2000. The Sun approaches maximum activity when the spacecraft is at high heliographic latitudes giving us for the first time the possibility to explore modulation of cosmic rays in the inner three-dimensional heliosphere during such conditions. Ulysses electron measurements in addition to the 1 AU ICE electron and IMP helium measurements allows us to investigate charge sign dependent modulation over a full 22-year solar magnetic cycle. Implications of these observations for our understanding of different modulation processes in the inner three-dimensional heliosphere are presented.

  8. Interstellar Dust in the Heliosheath: Tentative Discovery of the Magnetic Wall of the Heliosphere

    Science.gov (United States)

    Frisch, P. C.

    2005-12-01

    The evident identification of interstellar dust grains entrained in the magnetic wall of the heliosphere is reported. It is shown that the distribution of dust grains causing the weak polarization of light from nearby stars is consistent with polarization by small charged interstellar dust grains captured in the heliosphere magnetic wall (Tinbergen 1982, Frisch 2005). There is an offset between the deflected small charged polarizing dust grains, radius less than 0.2 microns, and the undeflected large grain population, radius larger than 0.2 microns. The region of maximum polarization is towards ecliptic coordinates lambda,beta = 295,0 deg, which is offset along the ecliptic longitude by about 35 deg from the heliosphere nose and extends to low ecliptic latitudes where the heliosphere magnetic wall is expected. An offset is also found between the best aligned dust grains, near lambda=281 deg to 220 deg, and the upwind direction of the undeflected inflow of large grains seen by Ulysses and Galileo. In the aligned-grain region, the polarization strength anti-correlates with ecliptic latitude, indicating that the magnetic wall was predominantly at negative ecliptic latitudes when these data were acquired. These data are consistent with model predictions for an interstellar magnetic field which is tilted by 60 deg with respect to the ecliptic plane, and parallel to the galactic plane. References: Tinbergen, 1982: AA, v105, p53; Frisch, 2005: to appear in ApJL.

  9. CMEs in the Heliosphere: I. A Statistical Analysis of the Observational Properties of CMEs Detected in the Heliosphere from 2007 to 2017 by STEREO/HI-1

    Science.gov (United States)

    Harrison, R. A.; Davies, J. A.; Barnes, D.; Byrne, J. P.; Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D.

    2018-05-01

    We present a statistical analysis of coronal mass ejections (CMEs) imaged by the Heliospheric Imager (HI) instruments on board NASA's twin-spacecraft STEREO mission between April 2007 and August 2017 for STEREO-A and between April 2007 and September 2014 for STEREO-B. The analysis exploits a catalogue that was generated within the FP7 HELCATS project. Here, we focus on the observational characteristics of CMEs imaged in the heliosphere by the inner (HI-1) cameras, while following papers will present analyses of CME propagation through the entire HI fields of view. More specifically, in this paper we present distributions of the basic observational parameters - namely occurrence frequency, central position angle (PA) and PA span - derived from nearly 2000 detections of CMEs in the heliosphere by HI-1 on STEREO-A or STEREO-B from the minimum between Solar Cycles 23 and 24 to the maximum of Cycle 24; STEREO-A analysis includes a further 158 CME detections from the descending phase of Cycle 24, by which time communication with STEREO-B had been lost. We compare heliospheric CME characteristics with properties of CMEs observed at coronal altitudes, and with sunspot number. As expected, heliospheric CME rates correlate with sunspot number, and are not inconsistent with coronal rates once instrumental factors/differences in cataloguing philosophy are considered. As well as being more abundant, heliospheric CMEs, like their coronal counterparts, tend to be wider during solar maximum. Our results confirm previous coronagraph analyses suggesting that CME launch sites do not simply migrate to higher latitudes with increasing solar activity. At solar minimum, CMEs tend to be launched from equatorial latitudes, while at maximum, CMEs appear to be launched over a much wider latitude range; this has implications for understanding the CME/solar source association. Our analysis provides some supporting evidence for the systematic dragging of CMEs to lower latitude as they propagate

  10. Taming the data wilderness with the VHO: Integrating heliospheric data sets

    Science.gov (United States)

    Schroeder, P.; Szabo, A.; Narock, T.

    Currently space physicists are faced with a bewildering array of heliospheric missions experiments and data sets available at archives distributed around the world Daunting even for those most familiar with the field physicists in other concentrations solar physics magnetospheric physics etc find locating the heliospheric data that they need extremely challenging if not impossible The Virtual Heliospheric Observatory VHO will help to solve this problem by creating an Application Programming Interface API and web portal that integrates these data sets to find the highest quality data for a given task The VHO will locate the best available data often found only at PI institutions rather than at national archives like the NSSDC The VHO will therefore facilitate a dynamic data environment where improved data products are made available immediately In order to accomplish this the VHO will enforce a metadata standard on participating data providers with sufficient depth to allow for meaningful scientific evaluation of similar data products The VHO will provide an automated way for secondary sites to keep mirrors of data archives up to date and encouraging the generation of secondary or added-value data products The VHO will interact seamlessly with the Virtual Solar Observatory VSO and other Virtual Observatories VxO s to allow for inter-disciplinary data searching Software tools for these data sets will also be available through the VHO Finally the VHO will provide linkages to the modeling community and will develop metadata standards for the

  11. The application of heliospheric imaging to space weather operations: Lessons learned from published studies

    Science.gov (United States)

    Harrison, Richard A.; Davies, Jackie A.; Biesecker, Doug; Gibbs, Mark

    2017-08-01

    The field of heliospheric imaging has matured significantly over the last 10 years—corresponding, in particular, to the launch of NASA's STEREO mission and the successful operation of the heliospheric imager (HI) instruments thereon. In parallel, this decade has borne witness to a marked increase in concern over the potentially damaging effects of space weather on space and ground-based technological assets, and the corresponding potential threat to human health, such that it is now under serious consideration at governmental level in many countries worldwide. Hence, in a political climate that recognizes the pressing need for enhanced operational space weather monitoring capabilities most appropriately stationed, it is widely accepted, at the Lagrangian L1 and L5 points, it is timely to assess the value of heliospheric imaging observations in the context of space weather operations. To this end, we review a cross section of the scientific analyses that have exploited heliospheric imagery—particularly from STEREO/HI—and discuss their relevance to operational predictions of, in particular, coronal mass ejection (CME) arrival at Earth and elsewhere. We believe that the potential benefit of heliospheric images to the provision of accurate CME arrival predictions on an operational basis, although as yet not fully realized, is significant and we assert that heliospheric imagery is central to any credible space weather mission, particularly one located at a vantage point off the Sun-Earth line.

  12. Opening a Window on ICME Evolution and GCR Modulation During Propagation in the Innermost Heliosphere

    Science.gov (United States)

    Winslow, R. M.; Lugaz, N.; Schwadron, N.; Farrugia, C. J.; Guo, J.; Wimmer-Schweingruber, R. F.; Wilson, J. K.; Joyce, C.; Jordan, A.; Lawrence, D. J.

    2017-12-01

    We use multipoint spacecraft observations to study interplanetary coronal mass ejection (ICME) evolution and subsequent galactic cosmic ray (GCR) modulation during propagation in the inner heliosphere. We illustrate ICME propagation effects through two different case studies. The first ICME was launched from the Sun on 29 December 2011 and was observed in near-perfect longitudinal conjunction at MESSENGER and STEREO A. Despite the close longitudinal alignment, we infer from force-free field modeling that the orientation of the underlying flux rope rotated ˜80o in latitude and ˜65o in longitude. Based on both spacecraft measurements as well as ENLIL model simulations of the steady state solar wind, we find that interactions involving magnetic reconnection with corotating structures in the solar wind dramatically alter the ICME magnetic field. In particular, we observed at STEREO A a highly turbulent region with distinct properties within the flux rope that was not observed at MESSENGER; we attribute this region to interaction between the ICME and a heliospheric plasma sheet/current sheet. This is a concrete example of a sequence of events that can increase the complexity of ICMEs during propagation and should serve as a caution on using very distant observations to predict the geoeffectiveness of large interplanetary transients. Our second case study investigates changes with heliospheric distance in GCR modulation by an ICME event (launched on 12 February 2014) observed in near-conjunction at all four of the inner solar system planets. The ICME caused Forbush decreases (FDs) in the GCR count rates at Mercury (MESSENGER), Earth/Moon (ACE/LRO), and Mars (MSL). At all three locations, the pre-ICME background GCR rate was well-matched, but the depth of the FD of GCR fluxes with similar energy ranges diminished with distance from the Sun. A larger difference in FD size was observed between Mercury and Earth than between Earth and Mars, partly owing to the much larger

  13. Outer heliospheric radio emissions. II - Foreshock source models

    Science.gov (United States)

    Cairns, Iver H.; Kurth, William S.; Gurnett, Donald A.

    1992-01-01

    Observations of LF radio emissions in the range 2-3 kHz by the Voyager spacecraft during the intervals 1983-1987 and 1989 to the present while at heliocentric distances greater than 11 AU are reported. New analyses of the wave data are presented, and the characteristics of the radiation are reviewed and discussed. Two classes of events are distinguished: transient events with varying starting frequencies that drift upward in frequency and a relatively continuous component that remains near 2 kHz. Evidence for multiple transient sources and for extension of the 2-kHz component above the 2.4-kHz interference signal is presented. The transient emissions are interpreted in terms of radiation generated at multiples of the plasma frequency when solar wind density enhancements enter one or more regions of a foreshock sunward of the inner heliospheric shock. Solar wind density enhancements by factors of 4-10 are observed. Propagation effects, the number of radiation sources, and the time variability, frequency drift, and varying starting frequencies of the transient events are discussed in terms of foreshock sources.

  14. Energetic particles in the heliosphere and GCR modulation: Reviewing of SH-posters

    International Nuclear Information System (INIS)

    Struminsky, Alexei

    2013-01-01

    This rapporteur paper addresses the SH poster session titled 'Energetic particles in the heliosphere (solar and anomalous CRs, GCR modulation)' of the 23rd European Cosmic Ray Symposium (ECRS) and the 32nd Russian Cosmic Ray Conference (RCRC). The 65 posters presented are tentatively divided into five sections: Instruments and Methods; Solar Energetic Particles; Short Term Variations; Long Term Variations; Heliosphere.

  15. An Efficient Approximation of the Coronal Heating Rate for use in Global Sun-Heliosphere Simulations

    Science.gov (United States)

    Cranmer, Steven R.

    2010-02-01

    The origins of the hot solar corona and the supersonically expanding solar wind are still the subject of debate. A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a physically motivated way of specifying the coronal heating rate. Recent one-dimensional models have been found to reproduce many observed features of the solar wind by assuming the energy comes from Alfvén waves that are partially reflected, then dissipated by magnetohydrodynamic turbulence. However, the nonlocal physics of wave reflection has made it difficult to apply these processes to more sophisticated (three-dimensional) models. This paper presents a set of robust approximations to the solutions of the linear Alfvén wave reflection equations. A key ingredient of the turbulent heating rate is the ratio of inward-to-outward wave power, and the approximations developed here allow this to be written explicitly in terms of local plasma properties at any given location. The coronal heating also depends on the frequency spectrum of Alfvén waves in the open-field corona, which has not yet been measured directly. A model-based assumption is used here for the spectrum, but the results of future measurements can be incorporated easily. The resulting expression for the coronal heating rate is self-contained, computationally efficient, and applicable directly to global models of the corona and heliosphere. This paper tests and validates the approximations by comparing the results to exact solutions of the wave transport equations in several cases relevant to the fast and slow solar wind.

  16. Particle propagation and acceleration in the heliosphere

    International Nuclear Information System (INIS)

    Valdes-Galicia, J.F.; Quenby, J.J.; Mousas, X.

    1988-01-01

    A realistic model of interplanetary magnetic field perturbations has been constructed based on data taken on board spacecraft. The model has been used to study numerically pitch angle scattering suffered by energetic particles (1-100 MeV) as they propagate in the Heliosphere. These numerical experiments allow the determination of the pitch angle diffusion coefficient Dμ and the associated mean free path λ. Dμ is found to be always smaller than implied by quasi linear theory, leading to radial mean free paths (λ r ≅ 0.015 AU) that are at least 3 times larger. Inclusion of solar wind velocity measurements in the model producing V x B random electric fields permits the study of stochastic acceleration caused by these fields. Initial results show that these processes might be able to overcome the effects of adiabatic cooling caused by the expansion of the solar wind and thus be of some influence in cosmic ray acceleration when extrapolated to other astrophysical environments

  17. MODULATION OF GALACTIC ELECTRONS IN THE HELIOSPHERE DURING THE UNUSUAL SOLAR MINIMUM OF 2006–2009: A MODELING APPROACH

    International Nuclear Information System (INIS)

    Potgieter, M. S.; Vos, E. E.; Munini, R.; Boezio, M.; Felice, V. Di

    2015-01-01

    The last solar minimum activity period, and the consequent minimum modulation conditions for cosmic rays, was unusual. The highest levels of Galactic protons were recorded at Earth in late 2009 in contrast to expectations. A comprehensive model was used to study the proton modulation for the period from 2006 to 2009 in order to determine what basic processes were responsible for solar modulation during this period and why it differs from proton modulation during previous solar minimum modulation periods. This established model is now applied to studying the solar modulation of electron spectra as observed for 80 MeV–30 GeV by the PAMELA space detector from mid-2006 to the end of 2009. Over this period the heliospheric magnetic field had decreased significantly until the end of 2009 while the waviness of the heliospheric current sheet decreased moderately and the observed electron spectra increased by a factor of ∼1.5 at 1.0 GeV to ∼3.5 at 100 MeV. In order to reproduce the modulation evident from seven consecutive semesters, the diffusion coefficients had to increase moderately while maintaining the basic rigidity dependence. It is confirmed that the main diffusion coefficients are independent of rigidity below ∼0.5 GV, while the drift coefficient had to be reduced below this value. The 2006–2009 solar minimum epoch indeed was different than previously observed minima, at least since the beginning of the space exploration era. This period could be called “diffusion-dominated” as was also found for the modulation of protons

  18. The sun, the solar wind, and the heliosphere

    CERN Document Server

    Miralles, Mari Paz

    2011-01-01

    This volume presents a concise, up-to-date overview of current research on the observations, theoretical interpretations, and empirical and physical descriptions of the Sun, the Solar Wind, and the Heliosphere, from the solar interior outward to the planets.

  19. Formation of Heliospheric Arcs of Slow Solar Wind

    Energy Technology Data Exchange (ETDEWEB)

    Higginson, A. K.; Zurbuchen, T. H. [Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Antiochos, S. K.; DeVore, C. R. [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Wyper, P. F., E-mail: aleida@umich.edu [Department of Mathematical Sciences, Durham University, Durham DH1 3LE (United Kingdom)

    2017-05-01

    A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun’s atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.

  20. Voyager in-situ and Cassini Remote Measurements Suggest a Bubble-like Shape for the Global Heliosphere

    Science.gov (United States)

    Dialynas, K.; Krimigis, S. M.; Mitchell, D. G.; Decker, R. B.; Roelof, E. C.

    2017-12-01

    The Low Energy Charged Particle (LECP) in situ measurements from Voyager 1 and Voyager 2 (V1, V2) have revealed the reservoir of ions and electrons that constitute the heliosheath after crossing the termination shock 35 deg north and 32 deg south of the ecliptic plane at 94 and 84 astronomical units (1 AU=1.5x108 km), respectively. In August 2012, at 121.6 AU, V1 crossed the heliopause to enter the interstellar space, while V2 remains in the heliosheath since 2007. The advent of Energetic Neutral Atom (ENA, produced through charge exchange between ions and neutral particles flowing through the heliosphere) imaging, has revealed the global nature of the heliosheath at both high (5.2-55 keV, Cassini/Ion and Neutral Camera-INCA, from 10 AU) and low (INCA global imaging through ENA in overlapping energy bands provides a powerful tool for examining the spatial, temporal, and spectral evolution of the source hot plasma ions. Here we report 5.2-55 keV ENA global images of the heliosphere from Cassini/INCA and compare them with V1,2/LECP 28-53 keV ions measured within the heliosheath over a 13-year period (2003-2016). The similarity between the time profiles of ENA and ions establish that the heliosheath ions are the source of ENA. These measurements also demonstrate that the heliosphere responds promptly, within 2-3 years, to outward propagating solar wind changes (manifested in solar sunspot numbers and solar wind energy input) in both the upstream (nose) and downstream (tail) hemispheres. These results, taken together with the V1 measurement of a 0.5 nT interstellar magnetic field and the enhanced ratio between particle pressure and magnetic pressure in the heliosheath, constrain the shape of the global heliosphere: by contrast to the magnetosphere-like heliotail (that past modeling broadly assumed for more than 55 years), a more symmetric, diamagnetic bubble-like heliosphere, with few substantial tail-like features is revealed.

  1. Heliosphere Responds to a Large Solar Wind Intensification: Decisive Observations from IBEX

    Science.gov (United States)

    McComas, D. J.; Dayeh, M. A.; Funsten, H. O.; Heerikhuisen, J.; Janzen, P. H.; Reisenfeld, D. B.; Schwadron, N. A.; Szalay, J. R.; Zirnstein, E. J.

    2018-03-01

    Our heliosphere—the bubble in the local interstellar medium produced by the Sun’s outflowing solar wind—has finally responded to a large increase in solar wind output and pressure in the second half of 2014. NASA’s Interstellar Boundary Explorer (IBEX) mission remotely monitors the outer heliosphere by observing energetic neutral atoms (ENAs) returning from the heliosheath, the region between the termination shock and heliopause. IBEX observed a significant enhancement in higher energy ENAs starting in late 2016. While IBEX observations over the previous decade reflected a general reduction of ENA intensities, indicative of a deflating heliosphere, new observations show that the large (∼50%), persistent increase in the solar wind dynamic pressure has modified the heliosheath, producing enhanced ENA emissions. The combination of these new observations with simulation results indicate that this pressure is re-expanding our heliosphere, with the termination shock and heliopause already driven outward in the locations closest to the Sun. The timing between the IBEX observations, a large transient pressure enhancement seen by Voyager 2, and the simulations indicates that the pressure increase propagated through the heliosheath, reflected off the heliopause, and the enhanced density of the solar wind filled the heliosheath behind it before generating significantly enhanced ENA emissions. The coming years should see significant changes in anomalous cosmic rays, galactic cosmic radiation, and the filtration of interstellar neutral atoms into the inner heliosphere.

  2. Cosmic Rays in the Heliosphere: Requirements for Future Observations

    Science.gov (United States)

    Mewaldt, R. A.

    2013-06-01

    Since the publication of Cosmic Rays in the Heliosphere in 1998 there has been great progress in understanding how and why cosmic rays vary in space and time. This paper discusses measurements that are needed to continue advances in relating cosmic ray variations to changes in solar and interplanetary activity and variations in the local interstellar environment. Cosmic ray acceleration and transport is an important discipline in space physics and astrophysics, but it also plays a critical role in defining the radiation environment for humans and hardware in space, and is critical to efforts to unravel the history of solar activity. Cosmic rays are measured directly by balloon-borne and space instruments, and indirectly by ground-based neutron, muon and neutrino detectors, and by measurements of cosmogenic isotopes in ice cores, tree-rings, sediments, and meteorites. The topics covered here include: what we can learn from the deep 2008-2009 solar minimum, when cosmic rays reached the highest intensities of the space era; the implications of 10Be and 14C isotope archives for past and future solar activity; the effects of variations in the size of the heliosphere; opportunities provided by the Voyagers for discovering the origin of anomalous cosmic rays and measuring cosmic-ray spectra in interstellar space; and future space missions that can continue the exciting exploration of the heliosphere that has occurred over the past 50 years.

  3. ASHI: An All Sky Heliospheric Imager for Viewing Thomson-Scattered Light

    Science.gov (United States)

    Buffington, A.; Jackson, B. V.; Yu, H. S.; Hick, P. P.; Bisi, M. M.

    2017-12-01

    We have developed, and are now making a detailed design for an All-Sky Heliospheric Imager (ASHI), to fly on future deep-space missions. ASHI's principal long-term objective is acquisition of a precision photometric map of the inner heliosphere as viewed from deep space. Photometers on the twin Helios spacecraft, the Solar Mass Ejection Imager (SMEI) upon the Coriolis satellite, and the Heliospheric Imagers (HIs) upon the Solar-TErrestrial RElations Observatory (STEREO) twin spacecraft, all indicate an optimum instrument design for visible-light Thomson-scattering observations. This design views a hemisphere of sky starting a few degrees from the Sun. Two imagers can cover almost all of the whole sky. A key photometric specification for ASHI is 0.1% differential photometry: this enables the three dimensional reconstruction of density starting from near the Sun and extending outward. SMEI analyses have demonstrated the success of this technique: when employed by ASHI, this will provide an order of magnitude better resolution in 3-D density over time. We augment this analysis to include velocity, and these imagers deployed in deep space can thus provide high-resolution comparisons both of direct in-situ density and velocity measurements to remote observations of solar wind structures. In practice we find that the 3-D velocity determinations provide the best tomographic timing depiction of heliospheric structures. We discuss the simple concept behind this, and present recent progress in the instrument design, and its expected performance specifications. A preliminary balloon flight of an ASHI prototype is planned to take place next Summer.

  4. 3D Embedded Reconfigurable Riometer for Heliospheric Space Missions

    Science.gov (United States)

    Dekoulis, George

    2016-07-01

    This paper describes the development of a new three-dimensional embedded reconfigurable Riometer for performing remote sensing of planetary magnetospheres. The system couples the in situ measurements of probe or orbiter magnetospheric space missions. The new prototype features a multi-frequency mode that allows measurements at frequencies, where heliospheric physics events' signatures are distinct on the ionized planetary plasma. For our planet similar measurements are meaningful for frequencies below 55 MHz. Observation frequencies above 55 MHz yield to direct measurements of the Cosmic Microwave Background intensity. The system acts as a prototyping platform for subsequent space exploration phased-array imaging experiments, due to its high-intensity scientific processing capabilities. The performance improvement over existing systems in operation is in the range of 80%, due to the state-of-the-art hardware and scientific processing used.

  5. Heliospheric Magnetic Fields, Energetic Particles, and the Solar Cycle

    Indian Academy of Sciences (India)

    tribpo

    from interstellar space penetrate deep into the heliosphere before being ionized by .... program was formally terminated in 1997, Pioneer-10 is still tracked. Since the last .... already been uncovered, and how many secrets it still holds.

  6. The Structure of the Heliosphere with Solar Cycle and Its Effect on the Conditions in the Local ISM

    Science.gov (United States)

    Opher, M.; Drake, J. F.; Toth, G.; Swisdak, M.; Michael, A.; Kornbleuth, M. Z.; Zieger, B.

    2017-12-01

    We argued (Opher et al. 2015, Drake et al. 2015) that the magnetic tension of the solar magnetic field plays a crucial role in organizing the solar wind in the heliosheath into two jet-like structures. The heliosphere then has a "croissant"-like shape where the distance to the heliopause downtail is almost the same as towards the nose. Regardless of whether the heliospheric tail is split in two or has a long comet shape there is consensus that the magnetic field in the heliosheath behaves differently than previously expected - it has a "slinky" structure and is turbulent. In this presentation, we will discuss several aspects related with this new model. We will show that this structure persists when the solar magnetic field is treated as a dipole. We show how the heliosphere, with its "Croissant" shape, evolves when the solar wind with solar cycle conditions are included and when the neutrals are treated kinetically (with our new MHD-Kinetic code). Due to reconnection (and turbulence of the jets) there is a substantial amount of heliosheath material sitting on open field lines. We will discuss the impact of artificial dissipation of the magnetic field in driving mixing and how it evolves with the solar cycle. We will discuss as well the development of turbulence in the jets and its role in mixing the plasma in the heliosheath and LISM and controlling the global structure of the heliosphere. We will discuss how the conditions upstream of the heliosphere, in the local interstellar medium are affected by reconnection in the tail and how it evolves with solar cycle. Recently we established (Opher et al. 2017) that reconnection in the eastern flank of the heliosphere is responsible for the twist of the interstellar magnetic field (BISM) acquiring a strong east-west component as it approaches the Heliopause. Reconnection drives a rotational discontinuity (RD) that twists the BISM into the -T direction and propagates upstream in the interstellar medium toward the nose

  7. The Telemachus mission: dynamics of the polar sun and heliosphere

    Science.gov (United States)

    Roelof, E.

    Telemachus in Greek mythology was the faithful son of Ulysses. The Telemachus mission is envisioned as the next logical step in the exploration of the polar regions of the Sun and heliosphere so excitingly initiated by the ESA/NASA Ulysses mission. Telemachus is a polar solar-heliospheric mission described in the current NASA Sun-Earth Connections Roadmap (2003-2028) that has successfully undergone two Team X studies by NASA/JPL. The pioneering observations from Ulysses transformed our perception of the structure and dynamics of these polar regions through which flow the solar wind, magnetic fields and energetic particles that eventually populate most of the volume of the heliosphere. Ulysses carried only fields and particles detectors. Telemachus, in addition to modern versions of such essential in situ instruments, will carry imagers that will give solar astronomers a new viewpoint on coronal mass ejections and solar flares, as well as their first purely polar views of the photospheric magnetic field, thereby providing new helioseismology to probe the interior of the Sun. Unlike the RTG-powered Ulysses, the power for Telemachus will come simply from solar panels. Gravity assist encounters with Venus and Earth (twice) will yield ˜5 years of continuous in-ecliptic cruise science between 0.7 AU and 3.3 AU that will powerfully complement other contemporary solar-heliospheric missions. The Jupiter gravity assist, followed by a perihelion burn ˜8 years after launch, will place Telemachus in a permanent ˜0.2 AU by 2.5 AU heliographic polar orbit (inclination >80 deg) whose period will be 1.5 years. Telemachus will then pass over the solar poles at ˜0.4 AU (compared to 1.4 AU for Ulysses) and spend ˜2 weeks above 60 deg on each polar pass (alternating perihelions between east and west limbs as viewed from Earth). In 14 polar passes during a 10.5 year solar cycle, Telemachus would accumulate over half a year of polar science data. During the remainder of the time, it

  8. Status of Knowledge after Ulysses and SOHO: Session 2: Investigate the Links between the Solar Surface, Corona, and Inner Heliosphere.

    Science.gov (United States)

    Suess, Steven

    2006-01-01

    As spacecraft observations of the heliosphere have moved from exploration into studies of physical processes, we are learning about the linkages that exist between different parts of the system. The past fifteen years have led to new ideas for how the heliospheric magnetic field connects back to the Sun and to how that connection plays a role in the origin of the solar wind. A growing understanding these connections, in turn, has led to the ability to use composition, ionization state, the microscopic state of the in situ plasma, and energetic particles as tools to further analyze the linkages and the underlying physical processes. Many missions have contributed to these investigations of the heliosphere as an integrated system. Two of the most important are Ulysses and SOHO, because of the types of measurements they make, their specific orbits, and how they have worked to complement each other. I will review and summarize the status of knowledge about these linkages, with emphasis on results from the Ulysses and SOHO missions. Some of the topics will be the global heliosphere at sunspot maximum and minimum, the physics and morphology of coronal holes, the origin(s) of slow wind, SOHO-Ulysses quadrature observations, mysteries in the propagation of energetic particles, and the physics of eruptive events and their associated current sheets. These specific topics are selected because they point towards the investigations that will be carried out with Solar Orbiter (SO) and the opportunity will be used to illustrate how SO will uniquely contribute to our knowledge of the underlying physical processes.

  9. 2- to 3-kHz continuum emissions as possible indications of global heliospheric 'breathing'

    Science.gov (United States)

    Grzedzielski, S.; Lazarus, A. J.

    1993-01-01

    The paper analyzes the main features of 2- to 3-kHz heliospheric emissions in the context of a general heliospheric 'breathing' as inferred from the Voyager 2 solar wind average ram pressure data. Triggers for the three 3-kHz emission events seen to date are suggested, and good agreement is obtained in timing and expected postshock frequency for termination shock distances of about 90 AU. It is suggested that the visibility of the individual 3-kHz events and their observed upward frequency drift are enhanced when the postulated global heliospheric expansion results in the formation of a transient, compressed external plasma barrier around the heliopause that prevents radiation escape for several months. The average termination shock distance is estimated to be in the range 80-90 AU.

  10. Tracking heliospheric disturbances by interplanetary scintillation

    Directory of Open Access Journals (Sweden)

    M. Tokumaru

    2006-01-01

    Full Text Available Coronal mass ejections are known as a solar cause of significant geospace disturbances, and a fuller elucidation of their physical properties and propagation dynamics is needed for space weather predictions. The scintillation of cosmic radio sources caused by turbulence in the solar wind (interplanetary scintillation; IPS serves as an effective ground-based method for monitoring disturbances in the heliosphere. We studied global properties of transient solar wind streams driven by CMEs using 327-MHz IPS observations of the Solar-Terrestrial Environment Laboratory (STEL of Nagoya University. In this study, we reconstructed three-dimensional features of the interplanetary (IP counterpart of the CME from the IPS data by applying the model fitting technique. As a result, loop-shaped density enhancements were deduced for some CME events, whereas shell-shaped high-density regions were observed for the other events. In addition, CME speeds were found to evolve significantly during the propagation between the corona and 1 AU.

  11. Voyager observations of the interaction of the heliosphere with the interstellar medium

    Directory of Open Access Journals (Sweden)

    John D. Richardson

    2013-05-01

    Full Text Available This paper provides a brief review and update on the Voyager observations of the interaction of the heliosphere with the interstellar medium. Voyager has found many surprises: (1 a new energetic particle component which is accelerated at the termination shock (TS and leaks into the outer heliosphere forming a foreshock region; (2 a termination shock which is modulated by energetic particles and which transfers most of the solar wind flow energy to the pickup ions (not the thermal ions; (3 the heliosphere is asymmetric; (4 the TS does not accelerate anomalous cosmic rays at the Voyager locations; and (5 the plasma flow in the Voyagers 1 (V1 and 2 (V2 directions are very different. At V1 the flow was small after the TS and has recently slowed to near zero, whereas at V2 the speed has remained constant while the flow direction has turned tailward. V1 may have entered an extended boundary region in front of the heliopause (HP in 2010 in which the plasma flow speeds are near zero.

  12. Voyager observations of the interaction of the heliosphere with the interstellar medium.

    Science.gov (United States)

    Richardson, John D

    2013-05-01

    This paper provides a brief review and update on the Voyager observations of the interaction of the heliosphere with the interstellar medium. Voyager has found many surprises: (1) a new energetic particle component which is accelerated at the termination shock (TS) and leaks into the outer heliosphere forming a foreshock region; (2) a termination shock which is modulated by energetic particles and which transfers most of the solar wind flow energy to the pickup ions (not the thermal ions); (3) the heliosphere is asymmetric; (4) the TS does not accelerate anomalous cosmic rays at the Voyager locations; and (5) the plasma flow in the Voyagers 1 (V1) and 2 (V2) directions are very different. At V1 the flow was small after the TS and has recently slowed to near zero, whereas at V2 the speed has remained constant while the flow direction has turned tailward. V1 may have entered an extended boundary region in front of the heliopause (HP) in 2010 in which the plasma flow speeds are near zero.

  13. Tentative Identification of Interstellar Dust in the Magnetic Wall of the Heliosphere

    Science.gov (United States)

    Frisch, P. C.

    2006-06-01

    Data showing that light from nearby stars, Tinbergen (1982) and Piirola (1977), were acquired during the solar minimum of the mid-1970's when the magnetic wall was expected to form at negative ecliptic latitudes because the solar magnetic polarity was north-pole-positive. The polarization is seen primarily at negative ecliptic latitudes, consistent with the expected magnetic wall position. The interstellar magnetic field direction at the Sun is derived from these data. The small dust grains most likely to cause the polarization are also the grains excluded from the heliosphere by small gyroradii, <100 AU. The direction of maximum polarization is offset by ˜ 20 --40 deg. from the inflow direction of the large grains that are gravitationally focused in the heliosphere tail. Interstellar dust grains in and near the heliosphere form a potential contaminant of the cosmic microwave background signal, which should then be identifiable because the spatial behavior of these grains depends on the phase of the 22 year solar magnetic activity cycle. The author would like to thank NASA for supporting her research.

  14. Energetic neutral atom and interstellar flow observations with IBEX: Implications for the global heliosphere

    Energy Technology Data Exchange (ETDEWEB)

    Schwadron, N. A., E-mail: nschwadron@unh.edu [University of New Hampshire, Durham NH, 03824 (United States); Southwest Research Institute, San Antonio, TX, 78238 (United States); McComas, D. J.; Desai, M. I.; Fuselier, S. A. [Southwest Research Institute, San Antonio, TX, 78238 (United States); University of Texas, San Antonio, TX, 78249 (United States); Christian, E. R. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Funsten, H. O. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Moebius, E. [University of New Hampshire, Durham NH, 03824 (United States); Reno, M.; Scherrer, J.; Zirnstein, E. [Southwest Research Institute, San Antonio, TX, 78238 (United States)

    2016-03-25

    Since launch in Oct. 2008, IBEX, with its two energetic neutral atom (ENA) cameras, has provided humankind with the first-ever global images of the complex boundary separating the heliosphere from the local interstellar medium (LISM). IBEX’s energy-resolved all-sky maps, collected every six months, are yielding remarkable new insights into the heliospheres structure as it is shaped by the combined forces of the local interstellar flow, the local interstellar magnetic field (LISMF), and the evolving solar wind. IBEX has also acquired the first images of ENAs backscattered from the surface of the moon as well as global images of the magnetospheric response to solar wind disturbances. IBEX thus addresses all three Heliophysics science objectives set forth in the 2014 Science Plan for NASAs Science Mission Directorate (SMD) as well as the goals in the recent Solar and Space Physics Decadal Survey (NRC 2012). In addition, with the information it provides on the properties of the LISM and the LISMF, IBEX represents a unique bridge between heliophysics and astrophysics, and fills in critical knowledge for understanding the habitability of exoplanetary systems and the future habitability of Earth and the solar system. Because of the few-year time lag due to solar wind and ENA transport, IBEX observed the solar wind/ LISM interaction characteristic of declining phase/solar minimum conditions. In the continuing mission, IBEX captures the response of the interstellar boundaries to the changing structure of the solar wind in its transition toward the “mini” solar maximum and possibly the decline into the next solar minimum. The continuing IBEX mission affords never-to-be-repeated opportunities to coordinate global imaging of the heliospheric boundary with in-situ measurements by the Voyagers as they pass beyond the heliopause and start to directly sample the LISM.

  15. Remote Sensing of the Heliospheric Solar Wind using Radio ...

    Indian Academy of Sciences (India)

    tribpo

    Astr. (2000) 21, 439–444. Remote Sensing of the Heliospheric Solar Wind using Radio. Astronomy Methods and Numerical Simulations. S. Ananthakrishnan, National Center for Radio Astrophysics, Tata Institute of. Fundamental Research, Pune, India. Abstract. The ground-based radio astronomy method of interplanetary.

  16. PREFACE: 14th Annual International Astrophysics Conference: Linear and Nonlinear Particle Energization throughout the Heliosphere and Beyond

    Science.gov (United States)

    Zank, G. P.

    2015-09-01

    The 14th Annual International Astrophysics Conference was held at the Sheraton Tampa Riverwalk Hotel, Tampa, Florida, USA, during the week of 19-24 April 2015. The meeting drew some 75 participants from all over the world, representing a wide range of interests and expertise in the energization of particles from the perspectives of theory, modelling and simulations, and observations. The theme of the meeting was "Linear and Nonlinear Particle Energization throughout the Heliosphere and Beyond." Energetic particles are ubiquitous to plasma environments, whether collisionless such as the supersonic solar wind, the magnetospheres of planets, the exospheres of nonmagnetized planets and comets, the heliospheric-local interstellar boundary regions, interstellar space and supernova remnant shocks, and stellar wind boundaries. Energetic particles are found too in more collisional regions such as in the solar corona, dense regions of the interstellar medium, accretion flows around stellar objects, to name a few. Particle acceleration occurs wherever plasma boundaries, magnetic and electric fields, and turbulence are present. The meeting addressed the linear and nonlinear physical processes underlying the variety of particle acceleration mechanisms, the role of particle acceleration in shaping different environments, and acceleration processes common to different regions. Both theory and observations were addressed with a view to encouraging crossdisciplinary fertilization of ideas, concepts, and techniques. The meeting addressed all aspects of particle acceleration in regions ranging from the Sun to the interplanetary medium to magnetospheres, exospheres, and comets, the boundaries of the heliosphere, and beyond to supernova remnant shocks, galactic jets, stellar winds, accretion flows, and more. The format of the meeting included 25-minute presentations punctuated by two 40-minute talks, one by Len Fisk that provided an historical overview of particle acceleration in the

  17. The Downwind Hemisphere of the Heliosphere as Observed with IBEX-Lo from 2009 to 2015

    Science.gov (United States)

    Wurz, P.; Galli, A.; Schwadron, N.; Kucharek, H.; Moebius, E.; Bzowski, M.; Sokol, J. M.; Kubiak, M. A.; Funsten, H. O.; Fuselier, S. A.; McComas, D. J.

    2017-12-01

    The topic of this study is the vast region towards the tail of the heliosphere. To this end, we comprehensively analyzed energetic neutral hydrogen atoms (ENAs) of energies 10 eV to 2.5 keV from the downwind hemisphere of the heliosheath measured during the first 7 years of the IBEX (Interstellar Boundary Explorer) mission. Neutralized ions from the heliosheath (the region of slow solar wind plasma between termination shock and heliopause) can be remotely observed as ENAs down to 10 eV with the IBEX-Lo sensor onboard IBEX. This sensor covers those energies of the ion spectrum that dominate the total plasma pressure in the downwind region. So far, this region of the heliosphere has never been explored in-situ. Converting observations obtained near Earth orbit at these low energies to the original ion distributions in the heliocentric rest frame at 100 AU is very challenging, making the assessment of uncertainties and implicit assumptions crucial. From the maps of observed ENAs from the heliosheath and their uncertainties we derive observational constraints on heliospheric models for the downwind hemisphere. These constraints limit the possible range of 1) the distance of the termination shock, 2) the total plasma pressure across the termination shock, 3) the radial flow velocity of the heliosheath plasma, 4) the extinction length of said plasma, and finally 5) the dimension of the heliosheath in downwind directions. Because these parameters are coupled and because of observational limitations, we also need to characterize the degeneracy, i.e., the fact that different sets of parameters may reproduce the observations.

  18. Large-scale density structures in the outer heliosphere

    Science.gov (United States)

    Belcher, J. W.; Lazarus, A. J.; Mcnutt, R. L., Jr.; Gordon, G. S., Jr.

    1993-01-01

    The Plasma Science experiment on the Voyager 2 spacecraft has measured the solar wind density from 1 to 38 AU. Over this distance, the solar wind density decreases as the inverse square of the heliocentric distance. However, there are large variations in this density at a given radius. Such changes in density are the dominant cause of changes in the solar wind ram pressure in the outer heliosphere and can cause large perturbations in the location of the termination shock of the solar wind. Following a simple model suggested by Suess, we study the non-equilibrium, dynamic location of the termination shock as it responds to these pressure changes. The results of this study suggest that the termination shock is rarely if ever at its equilibrium distance and may depart from that distance by as much as 50 AU at times.

  19. Magnetic flux density in the heliosphere through several solar cycles

    Energy Technology Data Exchange (ETDEWEB)

    Erdős, G. [Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Balogh, A., E-mail: erdos.geza@wigner.mta.hu [The Blackett Laboratory, Imperial College London, London SW7 2BZ (United Kingdom)

    2014-01-20

    We studied the magnetic flux density carried by solar wind to various locations in the heliosphere, covering a heliospheric distance range of 0.3-5.4 AU and a heliolatitudinal range from 80° south to 80° north. Distributions of the radial component of the magnetic field, B{sub R} , were determined over long intervals from the Helios, ACE, STEREO, and Ulysses missions, as well as from using the 1 AU OMNI data set. We show that at larger distances from the Sun, the fluctuations of the magnetic field around the average Parker field line distort the distribution of B{sub R} to such an extent that the determination of the unsigned, open solar magnetic flux density from the average (|B{sub R} |) is no longer justified. We analyze in detail two methods for reducing the effect of fluctuations. The two methods are tested using magnetic field and plasma velocity measurements in the OMNI database and in the Ulysses observations, normalized to 1 AU. It is shown that without such corrections for the fluctuations, the magnetic flux density measured by Ulysses around the aphelion phase of the orbit is significantly overestimated. However, the matching between the in-ecliptic magnetic flux density at 1 AU (OMNI data) and the off-ecliptic, more distant, normalized flux density by Ulysses is remarkably good if corrections are made for the fluctuations using either method. The main finding of the analysis is that the magnetic flux density in the heliosphere is fairly uniform, with no significant variations having been observed either in heliocentric distance or heliographic latitude.

  20. A Heuristic Approach to Remove the Background Intensity on White-light Solar Images. I. STEREO /HI-1 Heliospheric Images

    Energy Technology Data Exchange (ETDEWEB)

    Stenborg, Guillermo; Howard, Russell A. [Space Science Division, U.S. Naval Research Laboratory, Washington, DC 20375 (United States)

    2017-04-10

    White-light coronal and heliospheric imagers observe scattering of photospheric light from both dust particles (the F-Corona) and free electrons in the corona (the K-corona). The separation of the two coronae is thus vitally important to reveal the faint K-coronal structures (e.g., streamers, co-rotating interaction regions, coronal mass ejections, etc.). However, the separation of the two coronae is very difficult, so we are content in defining a background corona that contains the F- and as little K- as possible. For both the LASCO-C2 and LASCO-C3 coronagraphs aboard the Solar and Heliospheric Observatory ( SOHO ) and the white-light imagers of the SECCHI suite aboard the Solar Terrestrial Relationships Observatory ( STEREO ), a time-dependent model of the background corona is generated from about a month of similar images. The creation of such models is possible because the missions carrying these instruments are orbiting the Sun at about 1 au. However, the orbit profiles for the upcoming Solar Orbiter and Solar Probe Plus missions are very different. These missions will have elliptic orbits with a rapidly changing radial distance, hence invalidating the techniques in use for the SOHO /LASCO and STEREO /SECCHI instruments. We have been investigating techniques to generate background models out of just single images that could be used for the Solar Orbiter Heliospheric Imager and the Wide-field Imager for the Solar Probe Plus packages on board the respective spacecraft. In this paper, we introduce a state-of-the-art, heuristic technique to create the background intensity models of STEREO /HI-1 data based solely on individual images, report on new results derived from its application, and discuss its relevance to instrumental and operational issues.

  1. Recurrent Cosmic-ray Variations as a Probe of the Heliospheric Magnetic Field

    Science.gov (United States)

    Burger, R. A.; Engelbrecht, E. E.

    2006-12-01

    A linear relationship between the observed 26-day recurrent cosmic-ray intensity variations and the global latitudinal gradient was first reported by Zhang (1997, ApJ, 488), who made extensive use of Ulysses data. This relationship is seen for all species considered and at all latitudes covered by the spacecraft. Burger and Hitge (2004, ApJL, 617) used a three-dimensional steady-state numerical modulation model and showed that a Fisk-type (Fisk 1996, JGR, 101) heliospheric magnetic field (HMF) can in principle explain these observations, at least at high latitudes. In this progress report we use a refinement of the Fisk-Parker hybrid HMF model of Burger and Hitge (2004) by Kruger (2006, MSc dissertation, NWU University) (see also Kruger, Burger and Hitge 2005, AGU Fall meeting abstracts SH23B-0341) to study these 26-day recurrent variations in more detail with the same modulation code. In Kruger's model the HMF is Parker-like at the highest latitudes, becomes Fisk- like at intermediate latitudes, and becomes Parker-like again in the region swept out by the wavy current sheet. By using an almost continuous range of latitudinal gradients for both solar magnetic polarity cycles and for both protons and electrons - in contrast to the limited number of values used by Burger and Hitge (2004) - the structure of the graphs of amplitude of the recurrent cosmic-ray intensity variations as function of global latitudinal gradient can be studied in detail. This was performed in a 100 AU model heliosphere for solar minimum conditions with the tilt angle of the heliospheric current sheet at 10 degrees. In all cases drift effects are included. We find that these curves for amplitude vs. latitudinal gradient are similar for protons and for electrons. By switching the sign of the modeled amplitudes when the latitudinal gradient becomes negative, the existence of a single relationship between the two quantities can be studied for the whole range of modeled latitudinal gradients. This

  2. Statistical Investigation and Modeling of Sungrazing Comets Discovered with the Solar and Heliospheric Observatory

    Science.gov (United States)

    Sekanina, Zdenek

    2002-02-01

    More than 300 sungrazing comets, most of them discovered with the Solar and Heliospheric Observatory (SOHO) coronagraphs since the beginning of 1996, are known to belong to the Kreutz group or system. Moving about the Sun in similar orbits, they are of indisputably common parentage and represent by far the most extensive data set in the history of investigations of cometary splitting. This study compares the SOHO sungrazers, which always disappear during their approach to the Sun, with the sungrazers detected earlier with the other space-borne coronagraphs (Solwind and Solar Maximum Mission [SMM]) as well as with the bright members of the Kreutz system, discovered from the ground between 1843 and 1970. Collected, summarized, and reviewed information on the sungrazers' light curves indicates that there is a difference of 20 mag (a factor of 108 in brightness) between the brightest sungrazer, C/1882 R1, and the faintest objects detectable with the SOHO instruments. The headless comet C/1887 B1 is suggested to be a transition object between the bright sungrazers and the coronagraphically discovered ones: its physical behavior was similar to that of the latter comets, but it survived the perihelion passage. This study also (1) examines temporal and spatial distributions of the SOHO sungrazers; (2) depicts correlations among their orbital elements; (3) distinguishes among tidally triggered, post-tidal, and terminal fragmentation; (4) reiterates the conclusion made in an earlier paper that post-tidal, secondary fragmentation events are occurring throughout the orbit, including the region of aphelion; (5) determines the relationship between a breakup's location in the orbit and the perturbations of the orbital elements of a fragment caused by the momentum it acquires during the separation from the parent; (6) shows that collisions of the Kreutz system comets with the Sun are clearly possible; (7) finds that minor fragments acquire enough extra momentum during each of the

  3. Helium Energetic Neutral Atoms from the Heliosphere: Perspectives for Future Observations

    Energy Technology Data Exchange (ETDEWEB)

    Swaczyna, Paweł; Grzedzielski, Stan; Bzowski, Maciej, E-mail: pswaczyna@cbk.waw.pl [Space Research Centre of the Polish Academy of Sciences (CBK PAN), Bartycka 18A, 00-716 Warsaw (Poland)

    2017-05-10

    Observations of energetic neutral atoms (ENAs) allow for remote sensing of plasma properties in distant regions of the heliosphere. So far, most of the observations have concerned only hydrogen atoms. In this paper, we present perspectives for observations of helium energetic neutral atoms (He ENAs). We calculated the expected intensities of He ENAs created by the neutralization of helium ions in the inner heliosheath and through the secondary ENA mechanism in the outer heliosheath. We found that the dominant source region for He ENAs is the inner heliosheath. The obtained magnitudes of intensity spectra suggest that He ENAs can be observed with future ENA detectors, as those planned on Interstellar Mapping and Acceleration Probe . Observing He ENAs is most likely for energies from a few to a few tens of keV/nuc. Estimates of the expected count rates show that the ratio of helium to hydrogen atoms registered in the detectors can be as low as 1:10{sup 4}. Consequently, the detectors need to be equipped with an appropriate mass spectrometer capability, allowing for recognition of chemical elements. Due to the long mean free paths of helium ions in the inner heliosheath, He ENAs are produced also in the distant heliospheric tail. This implies that observations of He ENAs can resolve its structure, which seems challenging from observations of hydrogen ENAs since energetic protons are neutralized before they progress deeper in the heliospheric tail.

  4. Is the S-Web the Secret to Observed Heliospheric Particle Distributions?

    Science.gov (United States)

    Higginson, A. K.; Antiochos, S. K.; DeVore, C. R.; Daldorff, L. K. S.; Wyper, P. F.; Ukhorskiy, A. Y.; Sorathia, K.

    2017-12-01

    Particle transport in the heliosphere remains an unsolved problem across energy regimes. Observations of slow solar wind show that plasma escapes from the closed-field corona, but ends up far away from the heliospheric current sheet, even though the release mechanisms are expected to occur at the HCS. Similarly, some impulsive SEP events have extreme longitudinal extents of 100 degrees or more. Recent theoretical and numerical work has shown that interchange reconnection near a coronal-hole corridor can release plasma from originally closed magnetic field lines into a large swath spread across the heliosphere, forming what is known as an S-Web arc. This is a promising mechanism for explaining both the slow solar wind, with its large latitudinal extent, and impulsive SEP particles, with their large longitudinal extent. Here we compute, for the first time, the dynamics of the S-Web when the photospheric driver is applied over a large portion of the solar surface compared to the scale of the driving. We examine the time scales for the interchange reconnection and compute the angular extent of the plasma released, in the context of understanding both the slow solar wind and flare-accelerated SEPs. We will make predictions for Solar Orbiter and Parker Solar Probe and discuss how these new measurements will help to both pinpoint the source of the slow solar wind and illuminate the transport mechanisms of wide-spread impulsive SEP events.

  5. Badhwar - O'Neill 2014 Galactic Cosmic Ray Flux Model Description

    Science.gov (United States)

    O'Neill, P. M.; Golge, S.; Slaba, T. C.

    2014-01-01

    The Badhwar-O'Neill (BON) Galactic Cosmic Ray (GCR) model is based on GCR measurements from particle detectors. The model has mainly been used by NASA to certify microelectronic systems and the analysis of radiation health risks to astronauts in space missions. The BON14 model numerically solves the Fokker-Planck differential equation to account for particle transport in the heliosphere due to diffusion, convection, and adiabatic deceleration under the assumption of a spherically symmetric heliosphere. The model also incorporates an empirical time delay function to account for the lag of the solar activity to reach the boundary of the heliosphere. This technical paper describes the most recent improvements in parameter fits to the BON model (BON14). Using a comprehensive measurement database, it is shown that BON14 is significantly improved over the previous version, BON11.

  6. A Tractable Estimate for the Dissipation Range Onset Wavenumber Throughout the Heliosphere

    Science.gov (United States)

    Engelbrecht, N. Eugene; Strauss, R. Du Toit

    2018-04-01

    The modulation of low-energy electrons in the heliosphere is extremely sensitive to the behavior of the dissipation range slab turbulence. The present study derives approximate expressions for the wavenumber at which the dissipation range on the slab turbulence power spectrum commences, by assuming that this onset occurs when dispersive waves propagating parallel to the background magnetic field gyroresonate with thermal plasma particles. This assumption yields results in reasonable agreement with existing spacecraft observations. These expressions are functions of the solar wind proton and electron temperatures, which are here modeled throughout the region where the solar wind is supersonic using a two-component turbulence transport model. The results so acquired are compared with extrapolations of existing models for the dissipation range onset wavenumber, and conclusions are drawn therefrom.

  7. Observations of Heliospheric Faraday Rotation (FR) and Interplanetary Scintillation (IPS) with the LOw Frequency ARray (LOFAR): Steps Towards Improving Space-Weather Forecasting Capabilities

    Science.gov (United States)

    Bisi, M. M.; Fallows, R. A.; Sobey, C.; Eftekhari, T.; Jensen, E. A.; Jackson, B. V.; Yu, H. S.; Hick, P. P.; Odstrcil, D.; Tokumaru, M.

    2015-12-01

    The phenomenon of space weather - analogous to terrestrial weather which describes the changing pressure, temperature, wind, and humidity conditions on Earth - is essentially a description of the changes in velocity, density, magnetic field, high-energy particles, and radiation in the near-Earth space environment including the effects of such changes on the Earth's magnetosphere, radiation belts, ionosphere, and thermosphere. Space weather can be considered to have two main strands: (i) scientific research, and (ii) applications. The former is self-explanatory, but the latter covers operational aspects which includes its forecasting. Understanding and forecasting space weather in the near-Earth environment is vitally important to protecting our modern-day reliance (militarily and commercially) on satellites, global-communication and navigation networks, high-altitude air travel (radiation concerns particularly on polar routes), long-distance power/oil/gas lines and piping, and for any future human exploration of space to list but a few. Two ground-based radio-observing remote-sensing techniques that can aid our understanding and forecasting of heliospheric space weather are those of interplanetary scintillation (IPS) and heliospheric Faraday rotation (FR). The LOw Frequency ARray (LOFAR) is a next-generation 'software' radio telescope centered in The Netherlands with international stations spread across central and northwest Europe. For several years, scientific observations of IPS on LOFAR have been undertaken on a campaign basis and the experiment is now well developed. More recently, LOFAR has been used to attempt scientific heliospheric FR observations aimed at remotely sensing the magnetic field of the plasma traversing the inner heliosphere. We present our latest progress using these two radio heliospheric-imaging remote-sensing techniques including the use of three-dimensional (3-D) modeling and reconstruction techniques using other, additional data as input

  8. Kinky heliospheric current sheet: Cause of CDAW-6 substorms

    International Nuclear Information System (INIS)

    Tsurutani, B.T.; Russell, C.T.; King, J.H.; Zwickl, R.D.; Lin, R.P.

    1984-01-01

    Two magnetospheric substorms and the intensification of the second are caused by interplanetary magnetic field and ram pressure changes associated with a kinky heliospheric current sheet (KHCS). The responsible interplanetary features occur in a highly compressed region between a solar flare-associated shock wave and the cold driver gas. The possibity that the interplanetary structure is a ''magnetic cloud'' is ruled out

  9. Energetic Particles in the Inner Heliosphere

    Science.gov (United States)

    Malandraki, Olga

    2016-07-01

    Solar Energetic Particle (SEP) events are a key ingredient of Solar-Terrestrial Physics both for fundamental research and space weather applications. SEP events are the defining component of solar radiation storms, contribute to radio blackouts in polar regions and are related to many of the fastest Coronal Mass Ejections (CMEs) driving major geomagnetic storms. In addition to CMEs, SEPs are also related to flares. In this work, the current state of knowledge on the SEP field will be reviewed. Key issues to be covered and discussed include: the current understanding of the origin, acceleration and transport processes of SEPs at the Sun and in the inner heliosphere, lessons learned from multi-spacecraft SEP observations, statistical quantification of the comparison of solar events and SEP events of the current solar cycle 24 with previous solar cycles, causes of the solar-cycle variations in SEP fluencies and composition, theoretical work and current SEP acceleration models. Furthermore, the outstanding issues that constitute a knowledge gap in the field will be presented and discussed, as well as future directions and expected advances from the observational and modeling perspective, also in view of the unique observations provided by the upcoming Solar Orbiter and Solar Probe Plus missions. Acknowledgement: This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324.

  10. Solar journey: The significance of our galactic environment for the heliosphere and earth

    CERN Document Server

    Frisch, Priscilla C

    2006-01-01

    Humans evolved when the Sun was in the great void of the Local Bubble. The Sun entered the present environment of interstellar clouds only during the late Quaternary. Astronomical data reveal these long and short term changes in our galactic environment. Theoretical models then tell us how these changes affect interplanetary particles, planetary magnetospheres, and the Earth itself. Cosmic rays leave an isotopic signature in the paleoclimate record that helps trace the solar journey through space. "Solar Journey: The Significance of Our Galactic Environment for the Heliosphere and Earth" lays the foundation for an interdisciplinary study of the influence of interstellar material on the solar system and Earth as we travel through the Milky Way Galaxy. The solar wind bubble responds dynamically to interstellar material flowing past the Sun, regulating interstellar gas, dust, and cosmic particle fluxes in the interplanetary medium and the Earth. Cones of interstellar gas and dust focused by solar gravity, the ma...

  11. Number density structures in the inner heliosphere

    Science.gov (United States)

    Stansby, D.; Horbury, T. S.

    2018-06-01

    Aims: The origins and generation mechanisms of the slow solar wind are still unclear. Part of the slow solar wind is populated by number density structures, discrete patches of increased number density that are frozen in to and move with the bulk solar wind. In this paper we aimed to provide the first in-situ statistical study of number density structures in the inner heliosphere. Methods: We reprocessed in-situ ion distribution functions measured by Helios in the inner heliosphere to provide a new reliable set of proton plasma moments for the entire mission. From this new data set we looked for number density structures measured within 0.5 AU of the Sun and studied their properties. Results: We identified 140 discrete areas of enhanced number density. The structures occurred exclusively in the slow solar wind and spanned a wide range of length scales from 50 Mm to 2000 Mm, which includes smaller scales than have been previously observed. They were also consistently denser and hotter that the surrounding plasma, but had lower magnetic field strengths, and therefore remained in pressure balance. Conclusions: Our observations show that these structures are present in the slow solar wind at a wide range of scales, some of which are too small to be detected by remote sensing instruments. These structures are rare, accounting for only 1% of the slow solar wind measured by Helios, and are not a significant contribution to the mass flux of the solar wind.

  12. Heliospheric Impact on Cosmic Rays Modulation

    Science.gov (United States)

    Tiwari, Bhupendra Kumar

    2016-07-01

    Heliospheric Impact on Cosmic RaysModulation B. K. Tiwari Department of Physics, A. P. S. University, Rewa (M.P.), btiwari70@yahoo.com Cosmic rays (CRs) flux at earth is modulated by the heliosphereric magnetic field and the structure of the heliosphere, controls by solar outputs and their variability. Sunspots numbers (SSN) is often treated as a primary indicator of solar activity (SA). GCRs entering the helioshphere are affected by the interplanetary magnetic field (IMF) and solar wind speed, their modulation varies with the varying solar activity. The observation based on data recoded from Omniweb data Centre for solar- interplanetary activity indices and monthly mean count rate of cosmic ray intensity (CRI) data from neutron monitors of different cut-off rigidities(Rc) (Moscow Rc=2.42Gv and Oulu Rc=0.80Gv). During minimum solar activity periodof solar cycle 23/24, the sun is remarkably quiet, weakest strength of the IMF and least dense and slowest, solar wind speed, whereas, in 2003, highest value of yearly averaged solar wind speed (~568 Km/sec) associated with several coronal holes, which generate high speed wind stream has been recorded. It is observed that GCRs fluxes reduces and is high anti-correlated with SSN (0.80) and IMF (0.86). CRI modulation produces by a strong solar flare, however, CME associated solar flare produce more disturbance in the interplanetary medium as well as in geomagnetic field. It is found that count rate of cosmic ray intensity and solar- interplanetary parameters were inverse correlated and solar indices were positive correlated. Keywords- Galactic Cosmic rays (GCRs), Sunspot number (SSN), Solar activity (SA), Coronal Mass Ejection (CME), Interplanetary magnetic field (IMF)

  13. NUMERICAL STUDY OF THE LONGITUDINALLY ASYMMETRIC DISTRIBUTION OF SOLAR ENERGETIC PARTICLES IN THE HELIOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    He, H.-Q.; Wan, W., E-mail: hqhe@mail.iggcas.ac.cn, E-mail: wanw@mail.iggcas.ac.cn [Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China)

    2015-06-22

    Solar energetic particles (SEPs) affect the solar–terrestrial space environment and are very important to space weather research. In this work, we numerically investigate the transport processes of SEPs in the three-dimensional interplanetary magnetic field, with an emphasis on the longitudinal distribution of SEPs in the heliosphere. We confirm our previous finding that there exists an east–west longitudinal asymmetry in the SEP intensities, i.e., with the same longitude separations between the solar source centers and the magnetic footpoint of the observer, the fluxes of SEP events originating from solar sources located on the eastern side of the nominal magnetic footpoint of the observer are systematically larger than those of the SEP events originating from sources located on the western side. We discuss the formation mechanism of this phenomenon, and conclude that the longitudinally asymmetric distribution of SEPs results from the east–west azimuthal asymmetry in the topology of the heliospheric magnetic field as well as the effects of perpendicular diffusion on the transport of SEPs in the heliosphere. Our results will be valuable to understanding Sun–Earth relations and useful for space weather forecasting.

  14. Short Wavelength Electromagnetic Perturbations Excited Near the Solar Probe Plus Spacecraft in the Inner Heliosphere: 2.5D Hybrid Modeling

    Science.gov (United States)

    Lipatov, Alexander S.; Sittler, Edward C.; Hartle, Richard E.; Cooper, John F.

    2011-01-01

    A 2.5D numerical plasma model of the interaction of the solar wind (SW) with the Solar Probe Plus spacecraft (SPPSC) is presented. These results should be interpreted as a basic plasma model derived from the SW-interaction with the spacecraft (SC), which could have consequences for both plasma wave and electron plasma measurements on board the SC in the inner heliosphere. Compression waves and electric field jumps with amplitudes of about 1.5 V/m and (12-18) V/m were also observed. A strong polarization electric field was also observed in the wing of the plasma wake. However, 2.5D hybrid modeling did not show excitation of whistler/Alfven waves in the upstream connected with the bidirectional current closure that was observed in short-time 3D modeling SPPSC and near a tether in the ionosphere. The observed strong electromagnetic perturbations may be a crucial point in the electromagnetic measurements planned for the future Solar Probe Plus (SPP) mission. The results of modeling electromagnetic field perturbations in the SW due to shot noise in absence of SPPSC are also discussed.

  15. Trajectories of inner and outer heliospheric spacecraft: Predicted through 1999

    Science.gov (United States)

    Parthasarathy, R.; King, Joseph H.

    1991-01-01

    Information is presented in tabular and graphical form on the trajectories of the international fleet of spacecraft that will be probing the far reaches of the heliosphere during the 1990s. In particular, the following spacecraft are addressed: Pioneer 10 and 11, Pioneer Venus Orbiter (PVO), Voyager 1 and 2, Galileo, Ulysses, Suisei, Sakigake, Giotto, International Cometary Explorer (ICE), and Interplanetary Monitoring Platform 8 (IMP 8). Yearly resolution listing of position information in inertial space are given for Pioneer and Voyager spacecraft from the times of their launches in the 1970s. One series of plots shows the radial distances, latitudes, and longitudes of the Pioneers and Voyagers. The solar ecliptic inertial coordinate system is used. In this system, the Z axis is normal to the ecliptic plane and the X axis is towards the first point of Aries (from Sun to Earth on the vernal equinox).

  16. Observations and Analyses of Heliospheric Faraday Rotation of a Coronal Mass Ejection (CME) Using the LOw Frequency ARray (LOFAR) and Space-Based Imaging Techniques

    Science.gov (United States)

    Bisi, Mario Mark; Jensen, Elizabeth; Sobey, Charlotte; Fallows, Richard; Jackson, Bernard; Barnes, David; Giunta, Alessandra; Hick, Paul; Eftekhari, Tarraneh; Yu, Hsiu-Shan; Odstrcil, Dusan; Tokumaru, Munetoshi; Wood, Brian

    2017-04-01

    Geomagnetic storms of the highest intensity are general driven by coronal mass ejections (CMEs) impacting the Earth's space environment. Their intensity is driven by the speed, density, and, most-importantly, their magnetic-field orientation and magnitude of the incoming solar plasma. The most-significant magnetic-field factor is the North-South component (Bz in Geocentric Solar Magnetic - GSM - coordinates). At present, there are no reliable prediction methods available for this magnetic-field component ahead of the in-situ monitors around the Sun-Earth L1 point. Observations of Faraday rotation (FR) can be used to attempt to determine average magnetic-field orientations in the inner heliosphere. Such a technique has already been well demonstrated through the corona, ionosphere, and also the interstellar medium. Measurements of the polarisation of astronomical (or spacecraft in superior conjunction) radio sources (beacons/radio frequency carriers) through the inner corona of the Sun to obtain the FR have been demonstrated but mostly at relatively-high radio frequencies. Here we show some initial results of true heliospheric FR using the Low Frequency Array (LOFAR) below 200 MHz to investigate the passage of a coronal mass ejection (CME) across the line of sight. LOFAR is a next-generation low-frequency radio interferometer, and a pathfinder to the Square Kilometre Array (SKA) - LOW telescope. We demonstrate preliminary heliospheric FR results through the analysis of observations of pulsar J1022+1001, which commenced on 13 August 2014 at 13:00UT and spanned over 150 minutes in duration. We also show initial comparisons to the FR results via various modelling techniques and additional context information to understand the structure of the inner heliosphere being detected. This observation could indeed pave the way to an experiment which might be implemented for space-weather purposes that will eventually lead to a near-global method for determining the magnetic

  17. Ion heating and energy partition at the heliospheric termination shock: hybrid simulations and analytical model

    Energy Technology Data Exchange (ETDEWEB)

    Gary, S Peter [Los Alamos National Laboratory; Winske, Dan [Los Alamos National Laboratory; Wu, Pin [BOSTON UNIV.; Schwadron, N A [BOSTON UNIV.; Lee, M [UNIV OF NEW HAMPSHIRE

    2009-01-01

    The Los Alamos hybrid simulation code is used to examine heating and the partition of dissipation energy at the perpendicular heliospheric termination shock in the presence of pickup ions. The simulations are one-dimensional in space but three-dimensional in field and velocity components, and are carried out for a range of values of pickup ion relative density. Results from the simulations show that because the solar wind ions are relatively cold upstream, the temperature of these ions is raised by a relatively larger factor than the temperature of the pickup ions. An analytic model for energy partition is developed on the basis of the Rankine-Hugoniot relations and a polytropic energy equation. The polytropic index {gamma} used in the Rankine-Hugoniot relations is varied to improve agreement between the model and the simulations concerning the fraction of downstream heating in the pickup ions as well as the compression ratio at the shock. When the pickup ion density is less than 20%, the polytropic index is about 5/3, whereas for pickup ion densities greater than 20%, the polytropic index tends toward 2.2, suggesting a fundamental change in the character of the shock, as seen in the simulations, when the pickup ion density is large. The model and the simulations both indicate for the upstream parameters chosen for Voyager 2 conditions that the pickup ion density is about 25% and the pickup ions gain the larger share (approximately 90%) of the downstream thermal pressure, consistent with Voyager 2 observations near the shock.

  18. Observations of Heliospheric Faraday Rotation (FR) and Interplanetary Scintillation (IPS): Steps Towards Investigating Bz Propagation Between the Sun and the Earth

    Science.gov (United States)

    Bisi, Mario M.; Fallows, Richard A.; Sobey, Charlotte; Eftekhari, Tarraneh; Jensen, Elizabeth A.; Jackson, Bernard V.; Yu, Hsiu-Shan; Hick, P. Paul; Odstrcil, Dusan; Tokumaru, Munetoshi; Oyuki Chang, M. T.

    2016-04-01

    Space weather - analogous to terrestrial weather (describing the changing pressure, temperature, wind, and humidity conditions on Earth) - is essentially a description of the changes in velocity, density, magnetic field, high-energy particles, and radiation in the near-Earth space environment including the effects of such on the Earth. Space weather can be considered to have two main strands: (i) scientific research, and (ii) applications. The former is self-explanatory, but the latter covers operational aspects including forecasting. Understanding and forecasting space weather near the Earth is of critical importance to protecting our modern-day reliance on satellites, global-communications and navigation networks, high-altitude air travel (radiation concerns particularly on polar routes), long-distance power/oil/gas lines and piping, and for any future human exploration of space to list but a few. This includes both military and commercial considerations. Two ground-based radio-observing techniques that can add to and lead our understanding and forecasting of heliospheric space weather are those of interplanetary scintillation (IPS) and heliospheric Faraday rotation (FR). We present our latest progress using these two radio heliospheric-imaging remote-sensing techniques including the use of three-dimensional (3-D) modelling and reconstruction techniques using other, additional data as input to support and better-interpret individual case-study results.

  19. A Small Mission Concept to the Sun-Earth Lagrangian L5 Point for Innovative Solar, Heliospheric and Space Weather Science

    Science.gov (United States)

    Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer, M.; Vial, J.-C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; hide

    2016-01-01

    We present a concept for a small mission to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science. The proposed INvestigation of Solar-Terrestrial Activity aNd Transients (INSTANT) mission is designed to identify how solar coronal magnetic fields drive eruptions, mass transport and particle acceleration that impact the Earth and the heliosphere. INSTANT is the first mission designed to (1) obtain measurements of coronal magnetic fields from space and (2) determine coronal mass ejection (CME) kinematics with unparalleled accuracy. Thanks to innovative instrumentation at a vantage point that provides the most suitable perspective view of the Sun-Earth system, INSTANT would uniquely track the whole chain of fundamental processes driving space weather at Earth. We present the science requirements, payload and mission profile that fulfill ambitious science objectives within small mission programmatic boundary conditions.

  20. A kinky heliospheric current sheet - Cause of CDAW-6 substorms

    Science.gov (United States)

    Tsurutani, B. T.; Russell, C. T.; King, J. H.; Zwickl, R. D.; Lin, R. P.

    1984-01-01

    Two magnetospheric substorms and the intensification of the second are caused by interplanetary magnetic field and ram pressure changes associated with a kinky heliospheric current sheet (KHCS). The responsible interplanetary features occur in a highly compressed region between a solar flare-associated shock wave and the cold driver gas. The possibility that the interplanetary structure is a 'magnetic cloud' is ruled out.

  1. Diagnostics of the Solar Wind and Global Heliosphere with Lyman-α Emission Measurements

    Science.gov (United States)

    Provornikova, E. P.; Izmodenov, V. V.; Laming, J. M.; Strachan, L.; Wood, B. E.; Katushkina, O. A.; Ko, Y.-K.; Tun Beltran, S.; Chakrabarti, S.

    2018-02-01

    We propose to develop an instrument measuring full sky intensity maps and spectra of interplanetary Lyman-α emission to reveal the global solar wind variability and the nature of the heliosphere and the local interstellar medium.

  2. From the Outer Heliosphere to the Local Bubble Comparisons of New Observations with Theory

    CERN Document Server

    Linsky, J. L; Möbius, E; Steiger, R

    2009-01-01

    The present volume provides a state-of-the-art synopsis of our current understanding of the dynamic heliosphere, the interstellar clouds surrounding it, the wider neighborhood of the local bubble, and their complex interactions. It is written by many of the researchers who have made key discoveries, observations, and modeling efforts that have led to dramatic progress in the field over the past 25 years. Thus the book is an essential research tool for space scientists and astronomers alike, including graduate students for whom it presents a single-point entrance into this complex yet fascinating field.

  3. Forward Modeling of Coronal Mass Ejection Flux Ropes in the Inner Heliosphere with 3DCORE

    Science.gov (United States)

    Möstl, C.; Amerstorfer, T.; Palmerio, E.; Isavnin, A.; Farrugia, C. J.; Lowder, C.; Winslow, R. M.; Donnerer, J. M.; Kilpua, E. K. J.; Boakes, P. D.

    2018-03-01

    Forecasting the geomagnetic effects of solar storms, known as coronal mass ejections (CMEs), is currently severely limited by our inability to predict the magnetic field configuration in the CME magnetic core and by observational effects of a single spacecraft trajectory through its 3-D structure. CME magnetic flux ropes can lead to continuous forcing of the energy input to the Earth's magnetosphere by strong and steady southward-pointing magnetic fields. Here we demonstrate in a proof-of-concept way a new approach to predict the southward field Bz in a CME flux rope. It combines a novel semiempirical model of CME flux rope magnetic fields (Three-Dimensional Coronal ROpe Ejection) with solar observations and in situ magnetic field data from along the Sun-Earth line. These are provided here by the MESSENGER spacecraft for a CME event on 9-13 July 2013. Three-Dimensional Coronal ROpe Ejection is the first such model that contains the interplanetary propagation and evolution of a 3-D flux rope magnetic field, the observation by a synthetic spacecraft, and the prediction of an index of geomagnetic activity. A counterclockwise rotation of the left-handed erupting CME flux rope in the corona of 30° and a deflection angle of 20° is evident from comparison of solar and coronal observations. The calculated Dst matches reasonably the observed Dst minimum and its time evolution, but the results are highly sensitive to the CME axis orientation. We discuss assumptions and limitations of the method prototype and its potential for real time space weather forecasting and heliospheric data interpretation.

  4. ION-SCALE TURBULENCE IN THE INNER HELIOSPHERE: RADIAL DEPENDENCE

    Energy Technology Data Exchange (ETDEWEB)

    Comisel, H.; Motschmann, U.; Büchner, J.; Narita, Y.; Nariyuki, Y. [University of Toyama, Faculty of Human Development, 3190, Gofuku, Toyama, 930-8555 (Japan)

    2015-10-20

    The evolution of the ion-scale plasma turbulence in the inner heliosphere is studied by associating the plasma parameters for hybrid-code turbulence simulations to the radial distance from the Sun via a Solar wind model based mapping procedure. Using a mapping based on a one-dimensional solar wind expansion model, the resulting ion-kinetic scale turbulence is related to the solar wind distance from the Sun. For this purpose the mapping is carried out for various values of ion beta that correspond to the heliocentric distance. It is shown that the relevant normal modes such as ion cyclotron and ion Bernstein modes will occur first at radial distances of about 0.2–0.3 AU, i.e., near the Mercury orbit. This finding can be used as a reference, a prediction to guide the in situ measurements to be performed by the upcoming Solar Orbiter and Solar Probe Plus missions. Furthermore, a radial dependence of the wave-vector anisotropy was obtained. For astrophysical objects this means that the spatial scales of filamentary structures in interstellar media or astrophysical jets can be predicted for photometric observations.

  5. The high latitude heliosphere. Proceedings. 28. ESLAB Symposium, Friedrichshafen (Germany), 19 - 21 Apr 1994.

    Science.gov (United States)

    Marsden, R. G.

    1995-04-01

    The following topics were dealt with: high latitude heliosphere, Ulysses mission, corona, spectra, coronal holes, composition, solar wind, He, plasma, streams, interplanetary magnetic field, plasma waves, radio bursts, energetic particles, cosmic rays, and interstellar gas.

  6. Intensity variation of cosmic rays near the heliospheric current sheet

    International Nuclear Information System (INIS)

    Badruddin, K.S.; Yadav, R.S.; Yadav, N.R.

    1985-01-01

    Cosmic ray intensity variations near the heliospheric current sheet-both above and below it-have been studied during 1964-76. Superposed epoch analysis of the cosmic ray neutron monitor data with respect to sector boundaries (i.e., heliospheric current sheet crossings) has been performed. In this analysis data from neutron monitors well distributed in latitude over the Earth's surface is used. First, this study has been made during the two solar activity minimum periods 1964-65 and 1975-76, using the data from Thule (cut-off rigidity O GV), Deep River (cut-off rigidity 1.02 GV), Rome (cut-off rigidity 6.32 GV) and Huancayo (cut-off rigidity 13.45 GV) neutron monitors. The data is analyzed from Deep River, Rome and Huancayo neutron monitors, for which data is available for the full period (1964-76), by dividing the periods according to the changes in solar activity, interplanetary magnetic field polarity and coronal holes. All these studies have shown a negative gradient with respect to heliomagnetic latitude (current sheet). These results have been discussed in the light of theoretical and observational evidences. Suggestions have been given to overcome the discrepancy between the observational and theoretical results. Further, possible explanations for these observational results have been suggested. (author)

  7. Small-scale gradients of charged particles in the heliospheric magnetic field

    International Nuclear Information System (INIS)

    Guo, Fan; Giacalone, Joe

    2014-01-01

    Using numerical simulations of charged-particles propagating in the heliospheric magnetic field, we study small-scale gradients, or 'dropouts,' in the intensity of solar energetic particles seen at 1 AU. We use two turbulence models, the foot-point random motion model and the two-component model, to generate fluctuating magnetic fields similar to spacecraft observations at 1 AU. The turbulence models include a Kolmogorov-like magnetic field power spectrum containing a broad range of spatial scales from those that lead to large-scale field-line random walk to small scales leading to resonant pitch-angle scattering of energetic particles. We release energetic protons (20 keV-10 MeV) from a spatially compact and instantaneous source. The trajectories of energetic charged particles in turbulent magnetic fields are numerically integrated. Spacecraft observations are mimicked by collecting particles in small windows when they pass the windows at a distance of 1 AU. We show that small-scale gradients in the intensity of energetic particles and velocity dispersions observed by spacecraft can be reproduced using the foot-point random motion model. However, no dropouts are seen in simulations using the two-component magnetic turbulence model. We also show that particle scattering in the solar wind magnetic field needs to be infrequent for intensity dropouts to form.

  8. Seven Years of Imaging the Global Heliosphere with IBEX

    Energy Technology Data Exchange (ETDEWEB)

    McComas, D. J.; Zirnstein, E. J. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Bzowski, M.; Kubiak, M. A.; Sokół, J. M. [Space Research Centre of the Polish Academy of Sciences, Bartycka 18A, 00-716, Warsaw (Poland); Dayeh, M. A.; Fuselier, S. A.; Szalay, J. R. [Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 (United States); Funsten, H. O. [Los Alamos National Laboratory, Intelligence and Space Research Division, P.O. Box 1663, Los Alamos, NM 87545 (United States); Janzen, P. H.; Reisenfeld, D. B. [University of Montana, 32 Campus Drive, Missoula, MT 59812 (United States); Kucharek, H.; Möbius, E.; Schwadron, N. A. [University of New Hampshire, Space Science Center, Morse Hall Rm 407, Durham, NH 03824 (United States); Tokumaru, M., E-mail: dmccomas@princeton.edu [Institute for Space-Earth Environmental Research, Nagoya University, Nagoya 464-8601 (Japan)

    2017-04-01

    The Interstellar Boundary Explorer ( IBEX ) has now operated in space for 7 years and returned nearly continuous observations that have led to scientific discoveries and reshaped our entire understanding of the outer heliosphere and its interaction with the local interstellar medium. Here we extend prior work, adding the 2014–2015 data for the first time, and examine, validate, initially analyze, and provide a complete 7-year set of Energetic Neutral Atom (ENA) observations from ∼0.1 to 6 keV. The data, maps, and documentation provided here represent the 10th major release of IBEX data and include improvements to various prior corrections to provide the citable reference for the current version of IBEX data. We are now able to study time variations in the outer heliosphere and interstellar interaction over more than half a solar cycle. We find that the Ribbon has evolved differently than the globally distributed flux (GDF), with a leveling off and partial recovery of ENAs from the GDF, owing to solar wind output flattening and recovery. The Ribbon has now also lost its latitudinal ordering, which reflects the breakdown of solar minimum solar wind conditions and exhibits a greater time delay than for the surrounding GDF. Together, the IBEX observations strongly support a secondary ENA source for the Ribbon, and we suggest that this be adopted as the nominal explanation of the Ribbon going forward.

  9. VOYAGER OBSERVATIONS OF MAGNETIC SECTORS AND HELIOSPHERIC CURRENT SHEET CROSSINGS IN THE OUTER HELIOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, J. D. [Kavli Center for Astrophysics and Space Science, Massachusetts Institute of Technology, Cambridge, 02139 (United States); Burlaga, L. F. [NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 (United States); Drake, J. F. [Department of Physics and Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States); Hill, M. E. [Applied Physics Laboratory, The Johns Hopkins University, Laurel, MD 20723 (United States); Opher, M., E-mail: jdr@space.mit.edu, E-mail: lburlagahsp@verizon.net, E-mail: drake@umd.edu, E-mail: Matthew.Hill@jhuapl.edu, E-mail: mopher@bu.edu [Astronomy Department, Boston University, 675 Commonwealth Avenue, Boston, MA 02215 (United States)

    2016-11-10

    Voyager 1 ( V1 ) has passed through the heliosheath and is in the local interstellar medium. Voyager 2 ( V2 ) has been in the heliosheath since 2007. The role of reconnection in the heliosheath is under debate; compression of the heliospheric current sheets (HCS) in the heliosheath could lead to rapid reconnection and a reconfiguration of the magnetic field topology. This paper compares the expected and actual amounts of time the Voyager spacecraft observe each magnetic sector and the number of HCS crossings. The predicted and observed values generally agree well. One exception is at Voyager 1 in 2008 and 2009, where the distribution of sectors is more equal than expected and the number of HCS crossings is small. Two other exceptions are at V1 in 2011–2012 and at V2 in 2012, when the spacecraft are in the opposite magnetic sector less than expected and see fewer HCS crossings than expected. These features are consistent with those predicted for reconnection, and consequently searches for other reconnection signatures should focus on these times.

  10. Spatial gradients of GCR protons in the inner heliosphere derived from Ulysses COSPIN/KET and PAMELA measurements

    Science.gov (United States)

    Gieseler, J.; Heber, B.

    2016-05-01

    Context. During the transition from solar cycle 23 to 24 from 2006 to 2009, the Sun was in an unusual solar minimum with very low activity over a long period. These exceptional conditions included a very low interplanetary magnetic field (IMF) strength and a high tilt angle, which both play an important role in the modulation of galactic cosmic rays (GCR) in the heliosphere. Thus, the radial and latitudinal gradients of GCRs are very much expected to depend not only on the solar magnetic epoch, but also on the overall modulation level. Aims: We determine the non-local radial and the latitudinal gradients of protons in the rigidity range from ~0.45 to 2 GV. Methods: This was accomplished by using data from the satellite-borne experiment Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) at Earth and the Kiel Electron Telescope (KET) onboard Ulysses on its highly inclined Keplerian orbit around the Sun with the aphelion at Jupiter's orbit. Results: In comparison to the previous A> 0 solar magnetic epoch, we find that the absolute value of the latitudinal gradient is lower at higher and higher at lower rigidities. This energy dependence is therefore a crucial test for models that describe the cosmic ray transport in the inner heliosphere.

  11. Enhancements of energetic particles near the heliospheric termination shock.

    Science.gov (United States)

    McDonald, Frank B; Stone, Edward C; Cummings, Alan C; Heikkila, Bryant; Lal, Nand; Webber, William R

    2003-11-06

    The spacecraft Voyager 1 is at a distance greater than 85 au from the Sun, in the vicinity of the termination shock that marks the abrupt slowing of the supersonic solar wind and the beginning of the extended and unexplored distant heliosphere. This shock is expected to accelerate 'anomalous cosmic rays', as well as to re-accelerate Galactic cosmic rays and low-energy particles from the inner Solar System. Here we report a significant increase in the numbers of energetic ions and electrons that persisted for seven months beginning in mid-2002. This increase differs from any previously observed in that there was a simultaneous increase in Galactic cosmic ray ions and electrons, anomalous cosmic rays and low-energy ions. The low-intensity level and spectral energy distribution of the anomalous cosmic rays, however, indicates that Voyager 1 still has not reached the termination shock. Rather, the observed increase is an expected precursor event. We argue that the radial anisotropy of the cosmic rays is expected to be small in the foreshock region, as is observed.

  12. Relative location of a powerful flare, the heliospheric current sheet and the Earth favourable for the onset of a strong geomagnetic storm

    International Nuclear Information System (INIS)

    Ivanov, K.G.; Kharshiladze, A.F.; Romashets, E.P.

    1992-01-01

    Problem of magnetic clouds propagation in regular-nonuniform internal heliosphere is discussed. High dependence of their retardation and consequently intensity of interplanetary and geomagnetic disturbances on mutual location of flares, heliospheric current sheet and the Earth is identified. Eight solar flares, four of which caused strong storms, and another four led to weak disturbances, all of them being in fair agreement with theoretical conclusions, are presented as examples

  13. Solar wind velocity and temperature in the outer heliosphere

    Science.gov (United States)

    Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

    1994-01-01

    At the end of 1992, the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were at heliocentric distances of 56.0, 37.3, and 39.0 AU and heliographic latitudes of 3.3 deg N, 17.4 deg N, and 8.6 deg S, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer 10 is on the opposite side of the Sun. All three spacecraft have working plasma analyzers, so intercomparison of data from these spacecraft provides important information about the global character of the solar wind in the outer heliosphere. The averaged solar wind speed continued to exhibit its well-known variation with solar cycle: Even at heliocentric distances greater than 50 AU, the average speed is highest during the declining phase of the solar cycle and lowest near solar minimum. There was a strong latitudinal gradient in solar wind speed between 3 deg and 17 deg N during the last solar minimum, but this gradient has since disappeared. The solar wind temperature declined with increasing heliocentric distance out to a heliocentric distance of at least 20 AU; this decline appeared to continue at larger heliocentric distances, but temperatures in the outer heliosphere were suprisingly high. While Pioneer 10 and Voyager 2 observed comparable solar wind temperatures, the temperature at Pioneer 11 was significantly higher, which suggests the existence of a large-scale variation of temperature with heliographic longitude. There was also some suggestion that solar wind temperatures were higher near solar minimum.

  14. Solar polar rotation and its effect on heliospheric neutral fluxes

    Science.gov (United States)

    Sokol, J. M.; Grzedzielski, S.; Bzowski, M.

    2016-12-01

    The magnetic field in the solar polar corona exhibit a regular "ray-like" structure associated with large polar coronal holes during solar minimum. The solar rotation twists the magnetic field lines of the expanding fast solar wind over the poles. The twist induces a toroidal component of the polar magnetic field which results in magnetic forces directed towards the rotation axis. That is tantamount to a (weak) zeta pinch, known also in other astrophysical contexts (e.g. AGN plasmas). The pinch compresses the polar solar corona plasma and a cone-like enhancement in the solar wind density forms along the rotation axis. Though the effect is likely very dynamic, a time independent description is used here to get an order-of-magnitude estimate. The weak pinch is treated as a 1st order perturbation to the zero-order radial flow. The obtained density enhancement may affect the near and far heliosphere, modifying the charge-exchange and electron impact ionization rates of neutral atoms in interplanetary space. The charge exchange is the most effective ionization process for hydrogen and oxygen atoms, and electron impact ionization is a significant loss reaction for the helium atoms at close distances to the Sun. The change in the polar density due to the solar polar corona rotation could be of importance in the inner heliosphere for low energy atoms. We will present the influence of this effect on interstellar neutral gas distribution and H ENA fluxes observed by IBEX.

  15. 26-Day Variations of 7 MeV Electrons at high Latitudes and their Implications on the Heliospheric Magnetic Field

    Science.gov (United States)

    Sternal, Oliver; Engelbrecht, Eugene; Burger, Renier; Dunzlaff, Phillip; Ferreira, Stefan; Fichtner, Horst; Heber, Bernd; Kopp, Andreas; Potgieter, Marius; Scherer, Klaus

    The transport of energetic particles in the heliosphere is usually described by the Parker trans-port equation including the physical processes of diffusion, drift, convection and adiabatic energy changes. The Ulysses spacecraft provides unique insight into the flux of MeV electrons at high latitudes. In this contribution, we compare our model results for the Parker HMF model and the Fisk-type Schwadron-Parker HMF model to Ulysses measurements. The elec-tron flux at high latitudes has been used as a remote sensing method to investigate the imprint of a Fisk-type HMF. We show here for the first time that such an imprint exists and deduce a limitation on the Fisk HMF angle β.

  16. Characteristics of solar and heliospheric ion populations observed near earth

    International Nuclear Information System (INIS)

    Gloeckler, G.

    1984-01-01

    The composition and spectra of ions in solar-energetic-particle and energetic-storm-particle events, of diffuse ions upstream of the earth bow shock, and of ions in deep-geomagnetic-tail plasmoids are characterized in a summary of in situ observations. Data are presented in graphs and tables, and remarkable similarities are noted in the distribution functions of the heliospheric ion populations. The solar wind, acting through acceleration mechanisms associated with shocks and turbulence, is identified as the major plasma source of suprathermal and energetic particles. 33 references

  17. HEMISPHERIC ASYMMETRIES OF SOLAR PHOTOSPHERIC MAGNETISM: RADIATIVE, PARTICULATE, AND HELIOSPHERIC IMPACTS

    International Nuclear Information System (INIS)

    McIntosh, Scott W.; Burkepile, Joan; Miesch, Mark; Markel, Robert S.; Sitongia, Leonard; Leamon, Robert J.; Gurman, Joseph B.; Olive, Jean-Philippe; Cirtain, Jonathan W.; Hathaway, David H.

    2013-01-01

    Among many other measurable quantities, the summer of 2009 saw a considerable low in the radiative output of the Sun that was temporally coincident with the largest cosmic-ray flux ever measured at 1 AU. Combining measurements and observations made by the Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO) spacecraft we begin to explore the complexities of the descending phase of solar cycle 23, through the 2009 minimum into the ascending phase of solar cycle 24. A hemispheric asymmetry in magnetic activity is clearly observed and its evolution monitored and the resulting (prolonged) magnetic imbalance must have had a considerable impact on the structure and energetics of the heliosphere. While we cannot uniquely tie the variance and scale of the surface magnetism to the dwindling radiative and particulate output of the star, or the increased cosmic-ray flux through the 2009 minimum, the timing of the decline and rapid recovery in early 2010 would appear to inextricably link them. These observations support a picture where the Sun's hemispheres are significantly out of phase with each other. Studying historical sunspot records with this picture in mind shows that the northern hemisphere has been leading since the middle of the last century and that the hemispheric ''dominance'' has changed twice in the past 130 years. The observations presented give clear cause for concern, especially with respect to our present understanding of the processes that produce the surface magnetism in the (hidden) solar interior—hemispheric asymmetry is the normal state—the strong symmetry shown in 1996 was abnormal. Further, these observations show that the mechanism(s) which create and transport the magnetic flux are slowly changing with time and, it appears, with only loose coupling across the equator such that those asymmetries can persist for a considerable time. As the current asymmetry persists and the basal energetics of the system continue to

  18. HEMISPHERIC ASYMMETRIES OF SOLAR PHOTOSPHERIC MAGNETISM: RADIATIVE, PARTICULATE, AND HELIOSPHERIC IMPACTS

    Energy Technology Data Exchange (ETDEWEB)

    McIntosh, Scott W.; Burkepile, Joan; Miesch, Mark; Markel, Robert S.; Sitongia, Leonard [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Gurman, Joseph B. [Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Olive, Jean-Philippe [Astrium SAS, 6 rue Laurent Pichat, F-75016 Paris (France); Cirtain, Jonathan W.; Hathaway, David H. [Marshall Space Flight Center, Huntsville, AL 35812 (United States)

    2013-03-10

    Among many other measurable quantities, the summer of 2009 saw a considerable low in the radiative output of the Sun that was temporally coincident with the largest cosmic-ray flux ever measured at 1 AU. Combining measurements and observations made by the Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO) spacecraft we begin to explore the complexities of the descending phase of solar cycle 23, through the 2009 minimum into the ascending phase of solar cycle 24. A hemispheric asymmetry in magnetic activity is clearly observed and its evolution monitored and the resulting (prolonged) magnetic imbalance must have had a considerable impact on the structure and energetics of the heliosphere. While we cannot uniquely tie the variance and scale of the surface magnetism to the dwindling radiative and particulate output of the star, or the increased cosmic-ray flux through the 2009 minimum, the timing of the decline and rapid recovery in early 2010 would appear to inextricably link them. These observations support a picture where the Sun's hemispheres are significantly out of phase with each other. Studying historical sunspot records with this picture in mind shows that the northern hemisphere has been leading since the middle of the last century and that the hemispheric ''dominance'' has changed twice in the past 130 years. The observations presented give clear cause for concern, especially with respect to our present understanding of the processes that produce the surface magnetism in the (hidden) solar interior-hemispheric asymmetry is the normal state-the strong symmetry shown in 1996 was abnormal. Further, these observations show that the mechanism(s) which create and transport the magnetic flux are slowly changing with time and, it appears, with only loose coupling across the equator such that those asymmetries can persist for a considerable time. As the current asymmetry persists and the basal energetics of the

  19. Multi-point Shock and Flux Rope Analysis of Multiple Interplanetary Coronal Mass Ejections around 2010 August 1 in the Inner Heliosphere

    Science.gov (United States)

    Möstl, C.; Farrugia, C. J.; Kilpua, E. K. J.; Jian, L. K.; Liu, Y.; Eastwood, J. P.; Harrison, R. A.; Webb, D. F.; Temmer, M.; Odstrcil, D.; Davies, J. A.; Rollett, T.; Luhmann, J. G.; Nitta, N.; Mulligan, T.; Jensen, E. A.; Forsyth, R.; Lavraud, B.; de Koning, C. A.; Veronig, A. M.; Galvin, A. B.; Zhang, T. L.; Anderson, B. J.

    2012-10-01

    We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions, Solar Dynamics Observatory/Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory (SDO/SOHO/STEREO), monitored several CMEs originating within tens of degrees from the solar disk center. We compare their imprints on four widely separated locations, spanning 120° in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE, and ARTEMIS near Earth and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures at Wind. The geomagnetic storm was intense, reaching two minima in the Dst index (≈ - 100 nT), and was caused by the sheath region behind the shock and one of two observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures. We also emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs.

  20. MULTI-POINT SHOCK AND FLUX ROPE ANALYSIS OF MULTIPLE INTERPLANETARY CORONAL MASS EJECTIONS AROUND 2010 AUGUST 1 IN THE INNER HELIOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Moestl, C.; Liu, Y.; Luhmann, J. G. [Space Science Laboratory, University of California, Berkeley, CA (United States); Farrugia, C. J. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH (United States); Kilpua, E. K. J. [Department of Physics, University of Helsinki, FI-00560 Helsinki (Finland); Jian, L. K. [Department of Astronomy, University of Maryland, College Park, MD (United States); Eastwood, J. P.; Forsyth, R. [The Blackett Laboratory, Imperial College, London (United Kingdom); Harrison, R. A.; Davies, J. A. [RAL Space, Harwell Oxford, Didcot (United Kingdom); Webb, D. F. [Institute for Scientific Research, Boston College, Newton, MA (United States); Temmer, M.; Rollett, T.; Veronig, A. M. [Kanzelhoehe Observatory-IGAM, Institute of Physics, University of Graz, A-8010 Graz (Austria); Odstrcil, D. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Nitta, N. [Solar and Astrophysics Laboratory, Lockheed Martin Advanced Technology Center, Palo Alto, CA (United States); Mulligan, T. [Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA (United States); Jensen, E. A. [ACS Consulting, Houston, TX (United States); Lavraud, B. [Institut de Recherche en Astrophysique et Planetologie, Universite de Toulouse (UPS), F-31400 Toulouse (France); De Koning, C. A., E-mail: christian.moestl@uni-graz.at [NOAA/SWPC, Boulder, Colorado (United States); and others

    2012-10-10

    We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions, Solar Dynamics Observatory/Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory (SDO/SOHO/STEREO), monitored several CMEs originating within tens of degrees from the solar disk center. We compare their imprints on four widely separated locations, spanning 120 Degree-Sign in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE, and ARTEMIS near Earth and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures at Wind. The geomagnetic storm was intense, reaching two minima in the Dst index ( Almost-Equal-To - 100 nT), and was caused by the sheath region behind the shock and one of two observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures. We also emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs.

  1. Interplanetary magnetic field according to measurements on the Fobos-1,-2 space vehicles. 3. Heliospheric substorm of August 5-7, 1988

    International Nuclear Information System (INIS)

    Ivanov, K.G.

    1995-01-01

    Three-phase disturbance of the interplanetary magnetic field was observed by FOBOS-1 and Fobos-2 space vehicles being at 10 million km distance from the Earth and by IMP-8 near-the-Earth satellite. Disturbance configuration and structure demonstrate that passing of nonstandard bend of heliospheric current layer is the reason of it. Structure, intensity and origination of disturbance enable to classify it as belonging to a category of heliospheric substorms. All three phases of interplanetary disturbance were represented in special near-the-Earth geomagnetic variations of polar cap. 9 refs

  2. A Heliospheric Weather Expert Service Centre for ESA's Space Situational Awareness Space Weather Activities

    Science.gov (United States)

    Barnes, D.; Perry, C. H.

    2017-12-01

    The Heliospheric Weather Expert Service Centre (H-ESC) is one of five thematic virtual centres that are currently being developed as part of ESA's Space Situational Awareness pre-operational Space Weather service. In this presentation we introduce the current products and service that the H-ESC is providing. The immediate and downstream user groups that the centre is aiming to support are discussed. A description is provided on how the H-ESC is largely built on adoption and tailoring of federated products from expert groups around Europe and how these can be used to add value to the overall system. Having only recently been established the H-ESC is continuing to address gaps in its capabilities. Some of the priorities for products, their assessment, validation and integration into the system are discussed together with plans for bespoke development activities tailored to specific end-user group needs.

  3. An new MHD/kinetic model for exploring energetic particle production in macro-scale systems

    Science.gov (United States)

    Drake, J. F.; Swisdak, M.; Dahlin, J. T.

    2017-12-01

    A novel MHD/kinetic model is being developed to explore magneticreconnection and particle energization in macro-scale systems such asthe solar corona and the outer heliosphere. The model blends the MHDdescription with a macro-particle description. The rationale for thismodel is based on the recent discovery that energetic particleproduction during magnetic reconnection is controlled by Fermireflection and Betatron acceleration and not parallel electricfields. Since the former mechanisms are not dependent on kineticscales such as the Debye length and the electron and ion inertialscales, a model that sheds these scales is sufficient for describingparticle acceleration in macro-systems. Our MHD/kinetic model includesmacroparticles laid out on an MHD grid that are evolved with the MHDfields. Crucially, the feedback of the energetic component on the MHDfluid is included in the dynamics. Thus, energy of the total system,the MHD fluid plus the energetic component, is conserved. The systemhas no kinetic scales and therefore can be implemented to modelenergetic particle production in macro-systems with none of theconstraints associated with a PIC model. Tests of the new model insimple geometries will be presented and potential applications will bediscussed.

  4. Heliospheric pick-up ions influencing thermodynamics and dynamics of the distant solar wind

    Directory of Open Access Journals (Sweden)

    H. J. Fahr

    2002-01-01

    Full Text Available Neutral interstellar H-atoms penetrate into the inner heliosphere and upon the event of ionization are converted into pick-up ions (PUIs. The magnetized solar wind flow incorporates these ions into the plasma bulk and enforces their co-motion. By nonlinear interactions with wind-entrained Alfvén waves, these ions are then processed in the comoving velocity space. The complete pick-up process is connected with forces acting back to the original solar wind ion flow, thereby decelerating and heating the solar wind plasma. As we show here, the resulting deceleration cannot be treated as a pure loading effect, but requires adequate consideration of the action of the pressure of PUI-scattered waves operating by the PUI pressure gradient. Hereby, it is important to take into proper account the stochastic acceleration which PUIs suffer from at their convection out of the inner heliosphere by quasi-linear interactions with MHD turbulences. Only then can the presently reported VOYAGER observations of solar wind decelerations and heatings in the outer heliosphere be understood in view of the most likely values of interstellar gas parameters, such as an H-atom density of 0.12 cm-3 . Solar wind protons (SWPs appear to be globally heated in their motion to larger solar distances. Ascribing the needed heat transfer to the action of suprathermal PUIs, which drive MHD waves that are partly absorbed by SWPs, in order to establish the observed SWP polytropy, we can obtain a quantitative expression for the solar wind proton pressure as a function of solar distance. This expression clearly shows the change from an adiabatic to a quasi-polytropic SWP behaviour with a decreasing polytropic index at increasing distances. This also allows one to calculate the average percentage of initial pick-up energy fed into the thermal proton energy. In a first order evaluation of this expression, we can estimate that about 10% of the initial PUI injection energy is eventually

  5. Energetic Particles at High Latitudes of the Heliosphere

    International Nuclear Information System (INIS)

    Zhang Ming

    2004-01-01

    Ulysses has by now made two complete out-of-ecliptic orbits around the sun. The first encounter of the solar poles occurred in 1994-1995, when the sun was near the minimum of its activity cycle, while the second one was in 2000-2001, when the sun was at solar maximum. To our surprise, energetic particles of all origins at high latitude are not much different from those we observe near the ecliptic for at least these two phases of solar cycle. The latitude gradients of galactic and anomalous cosmic rays are positive but small at the 1994-1995 solar minimum and almost zero at the 2000-2001 solar maximum, while temporal solar cycle variation dominates their flux variation at all latitudes. Solar energetic particles from all large gradual events can be seen at both Ulysses and Earth no matter how large their spatial separations from the solar event are, and the particle flux often reaches a uniform level in the entire inner heliosphere within a few days after event onset and remains so throughout the decay phase that can sometimes last over a month. Energetic particles accelerated by low-latitude CIRs can appear at high latitudes, far beyond the latitudinal range of CIRs. All these observations suggest that latitudinal transport of energetic particles is quite easy. In addition, because the average magnetic field is radial at the pole, The Ulysses observations indicate that parallel diffusion and drift in the radial direction need to be reduced at the poles relative to their equatorial values. To achieve such behaviors of particle transport, the heliospheric magnetic field needs a significant latitudinal component at the poles. A non-zero latitudinal magnetic field component can be produced by latitudinal motion of the magnetic field line in solar corona, which can be in form of either random walk suggested by Jokipii or large scale systematic motion suggested by Fisk

  6. Additional acceleration of solar-wind particles in current sheets of the heliosphere

    Directory of Open Access Journals (Sweden)

    V. Zharkova

    2015-04-01

    Full Text Available Particles of fast solar wind in the vicinity of the heliospheric current sheet (HCS or in a front of interplanetary coronal mass ejections (ICMEs often reveal very peculiar energy or velocity profiles, density distributions with double or triple peaks, and well-defined streams of electrons occurring around or far away from these events. In order to interpret the parameters of energetic particles (both ions and electrons measured by the WIND spacecraft during the HCS crossings, a comparison of the data was carried out with 3-D particle-in-cell (PIC simulations for the relevant magnetic topology (Zharkova and Khabarova, 2012. The simulations showed that all the observed particle-energy distributions, densities, ion peak velocities, electron pitch angles and directivities can be fitted with the same model if the heliospheric current sheet is in a status of continuous magnetic reconnection. In this paper we present further observations of the solar-wind particles being accelerated to rather higher energies while passing through the HCS and the evidence that this acceleration happens well before the appearance of the corotating interacting region (CIR, which passes through the spacecraft position hours later. We show that the measured particle characteristics (ion velocity, electron pitch angles and the distance at which electrons are turned from the HCS are in agreement with the simulations of additional particle acceleration in a reconnecting HCS with a strong guiding field as measured by WIND. A few examples are also presented showing additional acceleration of solar-wind particles during their passage through current sheets formed in a front of ICMEs. This additional acceleration at the ICME current sheets can explain the anticorrelation of ion and electron fluxes frequently observed around the ICME's leading front. Furthermore, it may provide a plausible explanation of the appearance of bidirectional "strahls" (field-aligned most energetic

  7. Photoemission of Single Dust Grains for Heliospheric Conditions

    Science.gov (United States)

    Spann, James F., Jr.; Venturini, Catherine C.; Abbas, Mian M.; Comfort, Richard H.

    2000-01-01

    Initial results of an experiment to measure the photoemission of single dust grains as a function of far ultraviolet wavelengths are presented. Coulombic forces dominate the interaction of the dust grains in the heliosphere. Knowledge of the charge state of dust grains, whether in a dusty plasma (Debye length grains is primarily determined by primary electron and ion collisions, secondary electron emission and photoemission due to ultraviolet sunlight. We have established a unique experimental technique to measure the photoemission of individual micron-sized dust grains in vacuum. This technique resolves difficulties associated with statistical measurements of dust grain ensembles and non-static dust beams. The photoemission yield of Aluminum Oxide 3-micron grains For wavelengths from 120-300 nm with a spectral resolution of 1 nm FWHM is reported. Results are compared to interplanetary conditions.

  8. Probing the Structure of Our Solar System's Edge

    Science.gov (United States)

    Hensley, Kerry

    2018-02-01

    The boundary between the solar wind and the interstellar medium (ISM) at the distant edge of our solar system has been probed remotely and directly by spacecraft, but questions about its properties persist. What can models tell us about the structure of this region?The Heliopause: A Dynamic BoundarySchematic illustrating different boundaries of our solar system and the locations of the Voyager spacecraft. [Walt Feimer/NASA GSFCs Conceptual Image Lab]As our solar system travels through interstellar space, the magnetized solar wind flows outward and pushes back on the oncoming ISM, forming a bubble called the heliosphere. The clash of plasmas generates a boundary region called the heliopause, the shape of which depends strongly on the properties of the solar wind and the local ISM.Much of our understanding of the outer heliosphere and the local ISM comes from observations made by the International Boundary Explorer (IBEX) and the Voyager 1 and Voyager 2 spacecraft. IBEX makes global maps of the flux of neutral atoms, while Voyagers 1 and 2 record the plasma density and magnetic field parameters along their trajectories as they exit the solar system. In order to interpret the IBEX and Voyager observations, astronomers rely on complex models that must capture both global and local effects.Simulations of the plasma density in the meridional plane of the heliosphere due to the interaction of the solar wind with the ISM for the case of a relatively dense ISM with a weak magnetic field. [Adapted from Pogorelov et al. 2017]Modeling the Edge of the Solar SystemIn this study, Nikolai Pogorelov (University of Alabama in Huntsville) and collaborators use a hybrid magneto-hydrodynamical (MHD) and kinetic simulation to capture fully the physical processes happening in the outer heliosphere.MHD models have been used to understand many aspects of plasma flow in the heliosphere. However, they struggle to capture processes that are better described kinetically, like charge exchange

  9. The radial distribution of cosmic rays in the heliosphere at solar maximum

    Science.gov (United States)

    McDonald, F. B.; Fujii, Z.; Heikkila, B.; Lal, N.

    2003-08-01

    To obtain a more detailed profile of the radial distribution of galactic (GCRs) and anomalous (ACRs) cosmic rays, a unique time in the 11-year solar activity cycle has been selected - that of solar maximum. At this time of minimum cosmic ray intensity a simple, straight-forward normalization technique has been found that allows the cosmic ray data from IMP 8, Pioneer 10 (P-10) and Voyagers 1 and 2 (V1, V2) to be combined for the solar maxima of cycles 21, 22 and 23. This combined distribution reveals a functional form of the radial gradient that varies as G 0/r with G 0 being constant and relatively small in the inner heliosphere. After a transition region between ˜10 and 20 AU, G 0 increases to a much larger value that remains constant between ˜25 and 82 AU. This implies that at solar maximum the changes that produce the 11-year modulation cycle are mainly occurring in the outer heliosphere between ˜15 AU and the termination shock. These observations are not inconsistent with the concept that Global Merged Interaction. regions (GMIRs) are the principal agent of modulation between solar minimum and solar maximum. There does not appear to be a significant change in the amount of heliosheath modulation occurring between the 1997 solar minimum and the cycle 23 solar maximum.

  10. A cone-like enhancement of polar solar corona plasma and its influence on heliospheric particles

    Science.gov (United States)

    Grzedzielski, Stan; Sokół, Justyna M.

    2017-04-01

    We will present results of the study of the properties of the solar wind plasma due to rotation of the polar solar corona. We focus in our study on the solar minimum conditions, when the polar coronal holes are well formed and the magnetic field in the solar polar corona exhibit almost regular "ray-like" structure. The solar rotation twists the magnetic field lines of the expanding fast polar solar wind and the resulting toroidal component of the field induces a force directed towards the rotation axis. This phenomenon is tantamount to a (weak) zeta pinch, known also in other astrophysical contexts (e.g. like in AGN jets). The pinch compresses the polar solar corona plasma and forms a cone-like enhancement of the solar wind density aligned with the rotation axis in the spherically symmetric case. The effect is likely very dynamic due to fast changing conditions in the solar corona, however in the study presented here, we assume a time independent description to get an order-of-magnitude estimate. The weak pinch is treated as a first-order perturbation to the zeroth-order radial flow. Following the assumptions based on the available knowledge about the plasma properties in the polar solar corona we estimated the most typical density enhancements. The cone like structure may extend as far from the Sun as tens of AU and thus will influence the heliospheric particles inside the heliosphere. An increase of the solar wind density in the polar region may be related with a decrease of the solar wind speed. Such changes of the solar wind plasma at high latitudes may modify the charge-exchange and electron impact ionization rates of heliospheric particles in interplanetary space. We will present their influence on the interstellar neutral gas and energetic neutral atoms observed by IBEX.

  11. Prospective Out-of-ecliptic White-light Imaging of Coronal Mass Ejections Traveling through the Corona and Heliosphere

    Science.gov (United States)

    Xiong, Ming; Davies, Jackie A.; Harrison, Richard A.; Zhou, Yufen; Feng, Xueshang; Xia, Lidong; Li, Bo; Liu, Ying D.; Hayashi, Keiji; Li, Huichao; Yang, Liping

    2018-01-01

    The in-flight performance of the Coriolis/SMEI and STEREO/HI instruments substantiates the high-technology readiness level of white-light (WL) imaging of coronal mass ejections (CMEs) in the inner heliosphere. The WL intensity of a propagating CME is jointly determined by its evolving mass distribution and the fixed Thomson-scattering geometry. From their in-ecliptic viewpoints, SMEI and HI, the only heliospheric imagers that have been flown to date, integrate the longitudinal dimension of CMEs. In this paper, using forward magnetohydrodynamic modeling, we synthesize the WL radiance pattern of a typical halo CME viewed from an out-of-ecliptic (OOE) vantage point. The major anatomical elements of the CME identified in WL imagery are a leading sheath and a trailing ejecta; the ejecta-driven sheath is the brightest feature of the CME. The sheath, a three-dimensional (3D) dome-like density structure, occupies a wide angular extent ahead of the ejecta itself. The 2D radiance pattern of the sheath depends critically on viewpoint. For a CME modeled under solar minimum conditions, the WL radiance pattern of the sheath is generally a quasi-straight band when viewed from an in-ecliptic viewpoint and a semicircular arc from an OOE viewpoint. The dependence of the radiance pattern of the ejecta-driven sheath on viewpoint is attributed to the bimodal nature of the 3D background solar wind flow. Our forward-modeling results suggest that OOE imaging in WL radiance can enable (1) a near-ecliptic CME to be continuously tracked from its coronal initiation, (2) the longitudinal span of the CME to be readily charted, and (3) the transporting speed of the CME to be reliably determined. Additional WL polarization measurements can significantly limit the ambiguity of localizing CMEs. We assert that a panoramic OOE view in WL would be highly beneficial in revealing CME morphology and kinematics in the hitherto-unresolved longitudinal dimension and hence for monitoring the propagation and

  12. Three-Dimensional Evolution of Flux-Rope CMEs and Its Relation to the Local Orientation of the Heliospheric Current Sheet

    Science.gov (United States)

    Isavnin, A.; Vourlidas, A.; Kilpua, E. K. J.

    2014-06-01

    Flux ropes ejected from the Sun may change their geometrical orientation during their evolution, which directly affects their geoeffectiveness. Therefore, it is crucial to understand how solar flux ropes evolve in the heliosphere to improve our space-weather forecasting tools. We present a follow-up study of the concepts described by Isavnin, Vourlidas, and Kilpua ( Solar Phys. 284, 203, 2013). We analyze 14 coronal mass ejections (CMEs), with clear flux-rope signatures, observed during the decay of Solar Cycle 23 and rise of Solar Cycle 24. First, we estimate initial orientations of the flux ropes at the origin using extreme-ultraviolet observations of post-eruption arcades and/or eruptive prominences. Then we reconstruct multi-viewpoint coronagraph observations of the CMEs from ≈ 2 to 30 R⊙ with a three-dimensional geometric representation of a flux rope to determine their geometrical parameters. Finally, we propagate the flux ropes from ≈ 30 R⊙ to 1 AU through MHD-simulated background solar wind while using in-situ measurements at 1 AU of the associated magnetic cloud as a constraint for the propagation technique. This methodology allows us to estimate the flux-rope orientation all the way from the Sun to 1 AU. We find that while the flux-ropes' deflection occurs predominantly below 30 R⊙, a significant amount of deflection and rotation happens between 30 R⊙ and 1 AU. We compare the flux-rope orientation to the local orientation of the heliospheric current sheet (HCS). We find that slow flux ropes tend to align with the streams of slow solar wind in the inner heliosphere. During the solar-cycle minimum the slow solar-wind channel as well as the HCS usually occupy the area in the vicinity of the solar equatorial plane, which in the past led researchers to the hypothesis that flux ropes align with the HCS. Our results show that exceptions from this rule are explained by interaction with the Parker-spiraled background magnetic field, which dominates

  13. ENERGETIC PARTICLE ANISOTROPIES AT THE HELIOSPHERIC BOUNDARY. II. TRANSIENT FEATURES AND RIGIDITY DEPENDENCE

    International Nuclear Information System (INIS)

    Florinski, V.; Roux, J. A. le; Stone, E. C.; Cummings, A. C.

    2015-01-01

    In the preceding paper, we showed that large second-order anisotropies of heliospheric ions measured by the Voyager 1 space probe during the August 2012 boundary crossing event could be explained by a magnetic shear across the heliopause preventing particles streaming along the magnetic field from escaping the inner heliosheath. According to Stone et al., the penetration distance of heliospheric ions into the outer heliosheath had a strong dependence on the particle’s Larmor radius. By comparing hydrogen, helium, and oxygen ions with the same energy per nucleon, these authors argued that this effect must be attributed to larger cyclotron radii of heavier species rather than differences in velocity. We propose that gradient drift in a nonuniform magnetic field was the cause of both the large second-order anisotropies and the spatial differentiation based on the ion’s rigidity. A latitudinal gradient of magnetic field strength of about 10% per AU between 2012.7 and 2012.9 could have provided drift motion sufficient to match both LECP and CRS Voyager 1 observations. We explain the transient intensity dropout observed prior to the heliocliff using flux tube structures embedded in the heliosheath and magnetically connected to interstellar space. Finally, this paper reports a new indirect measurement of the plasma radial velocity at the heliopause on the basis of the time difference between two cosmic-ray telescopes measuring the same intensity dropout

  14. ENERGETIC PARTICLE ANISOTROPIES AT THE HELIOSPHERIC BOUNDARY. II. TRANSIENT FEATURES AND RIGIDITY DEPENDENCE

    Energy Technology Data Exchange (ETDEWEB)

    Florinski, V.; Roux, J. A. le [Department of Space Sciences, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Stone, E. C.; Cummings, A. C. [Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-04-10

    In the preceding paper, we showed that large second-order anisotropies of heliospheric ions measured by the Voyager 1 space probe during the August 2012 boundary crossing event could be explained by a magnetic shear across the heliopause preventing particles streaming along the magnetic field from escaping the inner heliosheath. According to Stone et al., the penetration distance of heliospheric ions into the outer heliosheath had a strong dependence on the particle’s Larmor radius. By comparing hydrogen, helium, and oxygen ions with the same energy per nucleon, these authors argued that this effect must be attributed to larger cyclotron radii of heavier species rather than differences in velocity. We propose that gradient drift in a nonuniform magnetic field was the cause of both the large second-order anisotropies and the spatial differentiation based on the ion’s rigidity. A latitudinal gradient of magnetic field strength of about 10% per AU between 2012.7 and 2012.9 could have provided drift motion sufficient to match both LECP and CRS Voyager 1 observations. We explain the transient intensity dropout observed prior to the heliocliff using flux tube structures embedded in the heliosheath and magnetically connected to interstellar space. Finally, this paper reports a new indirect measurement of the plasma radial velocity at the heliopause on the basis of the time difference between two cosmic-ray telescopes measuring the same intensity dropout.

  15. A study of density modulation index in the inner heliospheric solar wind during solar cycle 23

    International Nuclear Information System (INIS)

    Bisoi, Susanta Kumar; Janardhan, P.; Ingale, M.; Subramanian, P.; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K.

    2014-01-01

    The ratio of the rms electron density fluctuations to the background density in the solar wind (density modulation index, ε N ≡ ΔN/N) is of vital importance for understanding several problems in heliospheric physics related to solar wind turbulence. In this paper, we have investigated the behavior of ε N in the inner heliosphere from 0.26 to 0.82 AU. The density fluctuations ΔN have been deduced using extensive ground-based observations of interplanetary scintillation at 327 MHz, which probe spatial scales of a few hundred kilometers. The background densities (N) have been derived using near-Earth observations from the Advanced Composition Explorer. Our analysis reveals that 0.001 ≲ ε N ≲ 0.02 and does not vary appreciably with heliocentric distance. We also find that ε N declines by 8% from 1998 to 2008. We discuss the impact of these findings on problems ranging from our understanding of Forbush decreases to the behavior of the solar wind dynamic pressure over the recent peculiar solar minimum at the end of cycle 23.

  16. Magnetic clouds seen at different locations in the heliosphere

    Directory of Open Access Journals (Sweden)

    L. Rodriguez

    2008-02-01

    Full Text Available We analyze two magnetic clouds (MCs observed in different points of the heliosphere. The main aim of the present study is to provide a link between the different aspects of this phenomenon, starting with information on the origins of the MCs at the Sun and following by the analysis of in-situ observations at 1 AU and at Ulysses. The candidate source regions were identified in SOHO/EIT and SOHO/MDI observations. They were correlated with H-α images that were obtained from ground-based observatories. Hints on the internal magnetic field configuration of the associated coronal mass ejections are obtained from LASCO C2 images. In interplanetary space, magnetic and plasma moments of the distribution function of plasma species (ACE/Ulysses were analyzed together with information on the plasma composition, and the results were compared between both spacecraft in order to understand how these structures interact and evolve in their cruise from the Sun to 5 AU. Additionally, estimates of global magnitudes of magnetic fluxes and helicity were obtained from magnetic field models applied to the data in interplanetary space. We have found that these magnetic characteristics were well kept from their solar source, up to 5 AU where Ulysses provided valuable information which, together with that obtained from ACE, can help to reinforce the correct matching of solar events and their interplanetary counterparts.

  17. On the shape and properties of the global heliosphere over the Solar Cycle with Voyager/LECP ions and Cassini/INCA ENAs

    Science.gov (United States)

    Dialynas, Konstantinos; Krimigis, Stamatios; Mitchell, Donald; Decker, Robert; Roelof, Edmond

    2017-04-01

    Voyager 1 (V1) and Voyager 2 (V2) have crossed the termination shock in 2004 (V1) and 2007(V2) and traversing the Heliosheath (HS) in the upstream (nose) hemisphere, while the Ion and Neutral Camera (INCA) on Cassini enables Energetic Neutral Atom (ENA) images of the celestial sphere that place the local ion measurements by each Voyager in a global context. We present an analysis of 5.2-55 keV ENA global images of the HS and 28-53 keV in-situ ions over an 11-year period (2003-2014) that corresponds to the declining phase of solar cycle 23 (SC23) and onset of SC24. The measurements reveal a coherent decrease and recovery between ENA in the global heliosphere and in-situ ions at V1/V2 during this time period, in overlapping energy bands, establishing that the HS ions are the source of >28 keV ENA. The similarity in the overall appearance of the images throughout the INCA energy range (5.2-55 keV), reveals that the source of ENAs at 5.2 keV ENA and ion variations with the Solar Sunspot Numbers (SSN) and solar wind parameters indicates that the Heliosphere responds promptly, within 2-3 years, to outward propagating solar wind changes in both the nose and anti-nose (tail) directions following the Solar Cycle (SC) phases. A detailed latitudinal examination of the global ENA emissions, verifies that the peak intensities between the nose and anti-nose directions are nearly similar, the power law ENA spectral index (γ) is largely the same near the equator in both the nose and anti-nose directions and displays similar spatial dependence with latitude. The totality of the ENA and in situ ion observations, together with the V1 measurement of a 0.5 nT interstellar magnetic field (ISMF) and recent modeling, suggest a "bubble-shape" heliosphere, i.e with little substantial tail-like feature. These observations are essential in determining the context for the measurements anticipated by the forthcoming IMAP mission.

  18. Modeling and Observation of Interstellar He+ Pickup Ions in the Inner Heliosphere

    Science.gov (United States)

    Chen, Junhong

    Interstellar pickup ions constitute a charged particle population that originates from interstellar neutrals inside the heliosphere. They are produced by photoionization, charge exchange with solar wind ions, and electron impact ionization (EI). Once ionized, they are picked up by the interplanetary magnetic field (IMF) and rapidly swept outward with the solar wind. Typically, pickup ion distributions have been described in terms of a velocity distribution function that evolves through fast pitch angle scattering followed by adiabatic cooling during radial transport in the reference frame of the solar wind [e.g., Vasyliunas & Siscoe, 1976, VS76 hereafter]. In the VS76 model, the slope of the isotropic velocity distributions is controlled by the combination of the ionization rate and the cooling process. Thus far, for the cooling index that relates the slope of the velocity distribution to the radial transport and expansion of the pickup ions a constant value of 3/2 has been widely used. The implicit assumptions to arrive at this value are immediate PUI isotropization due to pitch angle scattering and solar wind expansion with the square of the distance from the Sun. Any experimental determination of the cooling index depends on the knowledge of the ionization rate and its spatial variation, as well as solar wind and interplanetary conditions. In this thesis, we study their influences on the PUI cooling index and separate them by making use of the two complementary helium PUI data sets from SWICS instrument on the ACE spacecraft, and PLASTIC instrument on STEREO spacecraft. We use the pickup ion observations from ACE SIWCS in the last solar cycle to determine the cooling index, and the possible effects of the electron impact ionization on the determination of the cooling index. With pickup ion observations from STEREO PLASTIC, we determine how solar wind expansion patterns affect the cooling index. We find that the cooling index varies substantially with solar

  19. The Jovian and galactic electrons in the heliosphere as seen by the KET experiment on board the spacecraft named ULYSSE

    International Nuclear Information System (INIS)

    Rastoin, Cecile

    1995-01-01

    The KET electron telescope onboard the Ulysse spacecraft flawlessly provides measurements of electrons, protons and alphas of energies above some MeV. This present work focuses on the electron data analysis and interpretation from the Ulysse's launch in 90 to the beginning of 95. The first stage of the odyssey was the Jovian encounter in February 92. The MeV electrons are here used as markers of the magnetic field global structure. We specially study the complex and highly dynamic outer magnetosphere. With reference of previous fly-by, the KET observations permit to characterize the 10-hour modulation of the Jovian electron flux and spectrum and suggest a mechanism involving the rotation of the north low-latitude polar cap. The boundary layers are seen as thick regions with transitions from magnetosheath to magnetospheric particle populations and field properties. The electron anisotropy and flux discontinuities are investigated with support of field data and provide the first evidence of magnetic reconnection occurring around the Jovian magnetopause. Taking advantage of the gravity assistance of the giant planet, Ulysse dipped towards the south heliospheric regions. Along its trajectory KET has detected Jovian electrons in interplanetary space. The first type of events is non-diffusive, with rapid increases discovered by KET at less than 1 AU from the magnetosphere: Jovian electrons have probably escaped through reconnection process which preserves their spectrum modulation and anisotropy characteristics. The events of second category are diffusive, observed since launch up to 30 degrees south. This work highlights the roles of interplanetary shocks and of the heliospheric current sheet in the propagation. A 3D transport model including adiabatic deceleration is presented here and accounts for the Jovian electron flux detected along the Ulysse's trajectory. New estimates of the 3D diffusion coefficients are performed for MeV electrons: K(perpendicular) = 8 * 10

  20. Polar conic current sheets as sources and channels of energetic particles in the high-latitude heliosphere

    Science.gov (United States)

    Khabarova, Olga; Malova, Helmi; Kislov, Roman; Zelenyi, Lev; Obridko, Vladimir; Kharshiladze, Alexander; Tokumaru, Munetoshi; Sokół, Justyna; Grzedzielski, Stan; Fujiki, Ken'ichi; Malandraki, Olga

    2017-04-01

    The existence of a large-scale magnetically separated conic region inside the polar coronal hole has been predicted by the Fisk-Parker hybrid heliospheric magnetic field model in the modification of Burger and co-workers (Burger et al., ApJ, 2008). Recently, long-lived conic (or cylindrical) current sheets (CCSs) have been found from Ulysses observations at high heliolatitudes (Khabarova et al., ApJ, 2017). The characteristic scale of these structures is several times lesser than the typical width of coronal holes, and the CCSs can be observed at 2-3 AU for several months. CCS crossings in 1994 and 2007 are characterized by sharp decreases in the solar wind speed and plasma beta typical for predicted profiles of CCSs. In 2007, a CCS was detected directly over the South Pole and strongly highlighted by the interaction with comet McNaught. The finding is confirmed by restorations of solar coronal magnetic field lines that reveal the occurrence of conic-like magnetic separators over the solar poles both in 1994 and 2007. Interplanetary scintillation data analysis also confirms the existence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. The occurrence of long-lived CCSs in the high-latitude solar wind could shed light on how energetic particles reach high latitudes. Energetic particle enhancements up to tens MeV were observed by Ulysses at edges of CCSs both in 1994 and 2007. In 1994 this effect was clearer, probably due to technical reasons. Accelerated particles could be produced either by magnetic reconnection at the edges of a CCS in the solar corona or in the solar wind. We discuss the role of high-latitude CCSs in propagation of energetic particles in the heliosphere and revisit previous studies of energetic particle enhancements at high heliolatitudes. We also suggest that the existence of a CCS can modify the distribution of the solar wind as a function of heliolatitude and consequently impact ionization

  1. A Model for the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, S. K.; Mikić, Z.; Titov, V. S.; Lionello, R.; Linker, J. A.

    2011-04-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to ~60°, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind, and magnetic field for a time period preceding the 2008 August 1 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere and propose further tests of the model.

  2. MODELING THE SOLAR WIND AT THE ULYSSES , VOYAGER , AND NEW HORIZONS SPACECRAFT

    Energy Technology Data Exchange (ETDEWEB)

    Kim, T. K.; Pogorelov, N. V.; Zank, G. P. [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Elliott, H. A.; McComas, D. J. [Southwest Research Institute, San Antonio, TX 78238 (United States)

    2016-11-20

    The outer heliosphere is a dynamic region shaped largely by the interaction between the solar wind and the interstellar medium. While interplanetary magnetic field and plasma observations by the Voyager spacecraft have significantly improved our understanding of this vast region, modeling the outer heliosphere still remains a challenge. We simulate the three-dimensional, time-dependent solar wind flow from 1 to 80 astronomical units (au), where the solar wind is assumed to be supersonic, using a two-fluid model in which protons and interstellar neutral hydrogen atoms are treated as separate fluids. We use 1 day averages of the solar wind parameters from the OMNI data set as inner boundary conditions to reproduce time-dependent effects in a simplified manner which involves interpolation in both space and time. Our model generally agrees with Ulysses data in the inner heliosphere and Voyager data in the outer heliosphere. Ultimately, we present the model solar wind parameters extracted along the trajectory of the New Horizons spacecraft. We compare our results with in situ plasma data taken between 11 and 33 au and at the closest approach to Pluto on 2015 July 14.

  3. Modeling the Solar Wind at the Ulysses, Voyager, and New Horizons Spacecraft

    Science.gov (United States)

    Kim, T. K.; Pogorelov, N. V.; Zank, G. P.; Elliott, H. A.; McComas, D. J.

    2016-11-01

    The outer heliosphere is a dynamic region shaped largely by the interaction between the solar wind and the interstellar medium. While interplanetary magnetic field and plasma observations by the Voyager spacecraft have significantly improved our understanding of this vast region, modeling the outer heliosphere still remains a challenge. We simulate the three-dimensional, time-dependent solar wind flow from 1 to 80 astronomical units (au), where the solar wind is assumed to be supersonic, using a two-fluid model in which protons and interstellar neutral hydrogen atoms are treated as separate fluids. We use 1 day averages of the solar wind parameters from the OMNI data set as inner boundary conditions to reproduce time-dependent effects in a simplified manner which involves interpolation in both space and time. Our model generally agrees with Ulysses data in the inner heliosphere and Voyager data in the outer heliosphere. Ultimately, we present the model solar wind parameters extracted along the trajectory of the New Horizons spacecraft. We compare our results with in situ plasma data taken between 11 and 33 au and at the closest approach to Pluto on 2015 July 14.

  4. MODELING THE SOLAR WIND AT THE ULYSSES , VOYAGER , AND NEW HORIZONS SPACECRAFT

    International Nuclear Information System (INIS)

    Kim, T. K.; Pogorelov, N. V.; Zank, G. P.; Elliott, H. A.; McComas, D. J.

    2016-01-01

    The outer heliosphere is a dynamic region shaped largely by the interaction between the solar wind and the interstellar medium. While interplanetary magnetic field and plasma observations by the Voyager spacecraft have significantly improved our understanding of this vast region, modeling the outer heliosphere still remains a challenge. We simulate the three-dimensional, time-dependent solar wind flow from 1 to 80 astronomical units (au), where the solar wind is assumed to be supersonic, using a two-fluid model in which protons and interstellar neutral hydrogen atoms are treated as separate fluids. We use 1 day averages of the solar wind parameters from the OMNI data set as inner boundary conditions to reproduce time-dependent effects in a simplified manner which involves interpolation in both space and time. Our model generally agrees with Ulysses data in the inner heliosphere and Voyager data in the outer heliosphere. Ultimately, we present the model solar wind parameters extracted along the trajectory of the New Horizons spacecraft. We compare our results with in situ plasma data taken between 11 and 33 au and at the closest approach to Pluto on 2015 July 14.

  5. Heliospheric Observations of Energetic Particles

    Science.gov (United States)

    Summerlin, Errol J.

    2011-01-01

    Heliospheric observations of energetic particles have shown that, on long time averages, a consistent v^-5 power-law index arises even in the absence of transient events. This implies an ubiquitous acceleration process present in the solar wind that is required to generate these power-law tails and maintain them against adiabatic losses and coulomb-collisions which will cool and thermalize the plasma respectively. Though the details of this acceleration process are being debated within the community, most agree that the energy required for these tails comes from fluctuations in the magnetic field which are damped as the energy is transferred to particles. Given this source for the tail, is it then reasonable to assume that the turbulent LISM should give rise to such a power-law tail as well? IBEX observations clearly show a power-law tail of index approximately -5 in energetic neutral atoms. The simplest explanation for the origins of these ENAs are that they are energetic ions which have charge-exchanged with a neutral atom. However, this would imply that energetic ions possess a v^-5 power-law distribution at keV energies at the source of these ENAs. If the source is presumed to be the LISM, it provides additional options for explaining the, so called, IBEX ribbon. This presentation will discuss some of these options as well as potential mechanisms for the generation of a power-law spectrum in the LISM.

  6. Heliospheric Neutral Atom Spectra Between 0.01 and 6 keV fom IBEX

    Science.gov (United States)

    Fuselier, S. A.; Allegrini, F.; Bzowski, M.; Funsten, H. O.; Ghielmetti, A. G.; Gloeckler, G.; Heirtzler, D.; Janzen, P.; Kubiak, M.; Kucharek, H.; hide

    2012-01-01

    Since 2008 December, the Interstellar Boundary Explorer (IBEX) has been making detailed observations of neutrals from the boundaries of the heliosphere using two neutral atom cameras with overlapping energy ranges. The unexpected, yet defining feature discovered by IBEX is a Ribbon that extends over the energy range from about 0.2 to 6 keV. This Ribbon is superposed on a more uniform, globally distributed heliospheric neutral population. With some important exceptions, the focus of early IBEX studies has been on neutral atoms with energies greater than approx. 0.5 keV. With nearly three years of science observations, enough low-energy neutral atom measurements have been accumulated to extend IBEX observations to energies less than approx. 0.5 keV. Using the energy overlap of the sensors to identify and remove backgrounds, energy spectra over the entire IBEX energy range are produced. However, contributions by interstellar neutrals to the energy spectrum below 0.2 keV may not be completely removed. Compared with spectra at higher energies, neutral atom spectra at lower energies do not vary much from location to location in the sky, including in the direction of the IBEX Ribbon. Neutral fluxes are used to show that low energy ions contribute approximately the same thermal pressure as higher energy ions in the heliosheath. However, contributions to the dynamic pressure are very high unless there is, for example, turbulence in the heliosheath with fluctuations of the order of 50-100 km/s.

  7. MORE EVIDENCE THAT VOYAGER 1 IS STILL IN THE HELIOSPHERE

    International Nuclear Information System (INIS)

    Gloeckler, G.; Fisk, L. A.

    2015-01-01

    The investigators of the Voyager mission currently exploring the heliosheath have concluded and announced that Voyager 1 (V1) has crossed the heliopause and is now in the interstellar medium. This conclusion is based primarily on the plasma wave observations of Gurnett et al., which reveal a plasma electron density that resembles the density expected in the local interstellar medium. Fisk and Gloeckler have disputed the conclusion that V1 has crossed the heliopause, pointing out that to account for all the V1 observations, particularly the magnetic field direction together with the density, it is necessary to conclude that the higher densities observed by Gurnett et al. are due to compressed solar wind. In this Letter it is shown that the model of Fisk and Gloeckler for the nose region of the heliosheath can account in detail for the intensity and spectral shape of Energetic Neutral Hydrogen observed by the Interstellar Boundary Explorer (IBEX) in the directions of V1 and Voyager 2 (V2). A key feature of the Fisk and Gloeckler model is the existence of a region in the heliosheath where the solar wind is compressed and heated, followed by a region where the solar wind is compressed but cold. The region of cold compressed solar wind provides a unique explanation for the low-energy IBEX observations, and since this is the region where V1 must now reside, the low-energy IBEX observations provide strong evidence that V1 is still in the heliosphere

  8. Solar activity and heliosphere-wide cosmic ray modulation in mid-1982

    International Nuclear Information System (INIS)

    Cliver, E.W.; Mihalov, J.D.; Sheeley, N.R. Jr.; Howard, R.A.; Koomen, M.J.; Schwenn, R.

    1987-01-01

    A major episode of flare activity in June and July 1982 was accompaniedby a pair of heliosphere-wide cosmic ray modulation events. In each case, a large Forbush decrease (FD) at earth was followed in turn by apparently related decreases at Pioneer 11 (P11) and Pioneer 10 (P10). The Pioneer spacecraft were separated by --155 0 in ecliptic longitude. We reviewed white light coronagraph and near-sun (≤1 AU) satellite data to identify plausible solar origins of these modulation events. The first widespread intensity decrease (FD 1) can be attributed to the combined effects of a backside flare on June 3 from solar active region 18382/18383, located 23 0 in ecliptic longitude from Pioneer 10, and a visible disk flare from 18405 on June 6, when this region was 9 0 from Pioneer 11. The second widespread modulation event during this period (FD 2) may be linked to flares from active region 18474 on July 12 and 22. The July 12 flare was located 34 0 in azimuth from Pioneer 11, and the July 22 flare was 24 0 from Pioneer 10. Since even fast shocks would take --1 month to propagate to Pioneer 11 (12 AU) and --2 months to reach Pioneer 10 (28 AU) in mid-1982, these ''one-to-one'' associations must be regarded with caution. The processes of entrainment and coalescence can cause a given traveling interplanetary disturbance to lose its identify enroute to the outer heliosphere. The fact that we were able to identify plausible solar flare candidates for each of the four Forbushlike decreases observed at the Pioneer satellites (two each at P10 and P11), however, removes the need to invoke a chock from a single flare as the sole cause of either FD 1 (at both P10 and P11) or FD 2

  9. Short- and long-term efficacy of intragastric air-filled balloon (Heliosphere® BAG) among obese patients.

    Science.gov (United States)

    Giuricin, M; Nagliati, C; Palmisano, S; Simeth, C; Urban, F; Buri, L; Balani, A; de Manzini, N

    2012-11-01

    Obesity is an increasing health problem worldwide. The intragastric balloon as a temporary endoscopic treatment of obesity can play an important role among the aforementioned group of obese individuals. It can also be used as a preoperative test before subjecting patients to restrictive bariatric surgery. Furthermore, the intragastric device may be applied to patients affected by severe obesity as a "bridge treatment" before they undergo major surgery in order to reduce chances of operation-related risks. To date, there are insufficient data in the literature on the long-term results of the intragastric balloon. Our study includes an analysis of our experience with Heliosphere® BAG from 2006 through to 2010, concerning early weight loss and weight loss maintenance over at least 18 months since the device's removal. The 32 patients who completed the 6-month treatment had recorded a mean weight loss of 12.66 kg and a mean overweight loss of 24.37 % (SD, 12.74). A total of 16 patients are subjected to an 18-month follow-up. Their pretreatment and long-term body mass index (BMI) were calculated: 6 months later, when devices were removed, they showed a mean weight of 99.75 kg (SD, 17.90; p < 0.001) and a mean weight loss of 13.62 kg and 26.14 % (SD, 12.79). 18 months after removing Heliosphere® BAG, the 16 patients' mean BMI was 37.28 kg/m² (SD, 5.41; p = 0.004), with a mean weight of 103.56 kg (SD 17.25; p = 0.0125), and a mean weight loss of 9.8 kg or 18.2 % (SD, 12.07). Heliosphere® BAG enables modest short-term weight loss with little side effects, although mid/long-term follow-up may entail partial weight gain. We believe it can be considered a useful bridge treatment in bariatric surgery in order to reduce chances of preoperative risks.

  10. A Model fot the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, S. K.; Mikic, Z.; Titov, V. S.; Lionello, R.; Linker, J. A.

    2011-01-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to approx.60deg, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind, and magnetic field for a time period preceding the 2008 August 1 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere and propose further tests of the model. Key words: solar wind - Sun: corona - Sun: magnetic topology

  11. COMPARING CORONAL AND HELIOSPHERIC MAGNETIC FIELDS OVER SEVERAL SOLAR CYCLES

    Energy Technology Data Exchange (ETDEWEB)

    Koskela, J. S.; Virtanen, I. I.; Mursula, K., E-mail: jennimari.koskela@oulu.fi [University of Oulu, P.O. Box 3000, FI-90014 Oulu (Finland)

    2017-01-20

    Here we use the PFSS model and photospheric data from Wilcox Solar Observatory, SOHO /MDI, SDO/HMI, and SOLIS to compare the coronal field with heliospheric magnetic field measured at 1 au, compiled in the NASA/NSSDC OMNI 2 data set. We calculate their mutual polarity match and the power of the radial decay, p , of the radial field using different source surface distances and different number of harmonic multipoles. We find the average polarity match of 82% for the declining phase, 78%–79% for maxima, 76%–78% for the ascending phase, and 74%–76% for minima. On an average, the source surface of 3.25 R{sub S} gives the best polarity match. We also find strong evidence for solar cycle variation of the optimal source surface distance, with highest values (3.3 R{sub S}) during solar minima and lowest values (2.6 R{sub S}–2.7 R{sub S}) during the other three solar cycle phases. Raising the number of harmonic terms beyond 2 rarely improves the polarity match, showing that the structure of the HMF at 1 au is most of the time rather simple. All four data sets yield fairly similar polarity matches. Thus, polarity comparison is not affected by photospheric field scaling, unlike comparisons of the field intensity.

  12. International Living With a Star (ILWS), a new collaborative space program in Solar, Heliospheric and Solar-Terrestrial Physics

    Science.gov (United States)

    Opgenoorth, H. J.; Guhathakurta, M.; Liu, W.; Kosugi, T.; Zelenyi, L.

    2003-04-01

    research in solar-terrestrial studies, including all relevant data sources as well as theory and modeling. The future ILWS program will be supervised by an international steering committee, involving representatives from the 4 main space agencies NASA, ESA, ISAS, RSA, and, emphasising the importance of ground-based instrumentation in the systematic approach of the ILWS programme, also from the Canadian Space Agency (CSA). More specific work will be carried out through an IWLS Working Group, membership to which is open to space organizations committed to contribute to ILWS over the next decade. Adequate contributions to ILWS can include any of the following: - Space Flight Missions - Mission payloads or subsystems - Mission launch or tracking services - Additional data sources supporting S/C (sounding rockets, balloon, or ground-based) - Data dissemination, storage, distribution and value adding systems In addition topical ILWS Task Groups will be established as necessary to support specific ILWS-WG projects/studies. This poster will biefly summarize the origins, objectives, and provisional organizational structure for ILWS and how this program can benifit from and contribute to international collaborative efforts towards International Heliospheric Year (IHY).

  13. SUNWARD-PROPAGATING ALFVÉNIC FLUCTUATIONS OBSERVED IN THE HELIOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui; Wang, Chi [State Key Laboratory of Space Weather, National Space Science Center, CAS, Beijing, 100190 (China); Belcher, John W.; Richardson, John D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA (United States); He, Jiansen, E-mail: hli@spaceweather.ac.cn [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China)

    2016-06-10

    The mixture/interaction of anti-sunward-propagating Alfvénic fluctuations (AFs) and sunward-propagating Alfvénic fluctuations (SAFs) is believed to result in the decrease of the Alfvénicity of solar wind fluctuations with increasing heliocentric distance. However, SAFs are rarely observed at 1 au and solar wind AFs are found to be generally outward. Using the measurements from Voyager 2 and Wind , we perform a statistical survey of SAFs in the heliosphere inside 6 au. We first report two SAF events observed by Voyager 2 . One is in the anti-sunward magnetic sector with a strong positive correlation between the fluctuations of magnetic field and solar wind velocity. The other one is in the sunward magnetic sector with a strong negative magnetic field—velocity correlation. Statistically, the percentage of SAFs increases gradually with heliocentric distance, from about 2.7% at 1.0 au to about 8.7% at 5.5 au. These results provide new clues for understanding the generation mechanism of SAFs.

  14. Forbush decreases and particle acceleration in the outer heliosphere

    International Nuclear Information System (INIS)

    Van Allen, J.A.; Mihalov, J.D.

    1990-01-01

    Major solar flare activity in 1989 has provided examples of the local acceleration of protons at 28 AU (Pioneer 11) and of the propagation of Forbush decreases in galactic cosmic ray intensity to a heliocentric radial distance of 47 AU (Pioneer 10). The combination of these and previous data at lesser distances shows (a) that Forbush decreases propagate with essentially constant magnitude to (at least) 47 AU and with similar magnitude at widely different ecliptic longitudes and (b) that the times for recovery from such decreases become progressively greater as the radial distance increases, being of the order of months in the outer heliosphere. A phenomenological scheme for (b) is proposed and fresh support is given to the hypothesis that the solar cycle modulation of the galactic cosmic ray intensity is attributable primarily to overlapping Forbush decreases which are more frequent and of greater magnitude near times of maximum solar activity than at times of lesser activity

  15. Solar and Heliospheric Data Requirements: Going Further Than L1

    Science.gov (United States)

    Szabo, A.

    2011-01-01

    Current operational space weather forecasting relies on solar wind observations made by the ACE spacecraft located at the L1 point providing 30-40 minutes warning time. Some use is also made of SOHO and STEREO solar imaging that potentially can give multiple days of warning time. However, our understanding of the propagation and evolution of solar wind transients is still limited resulting in a typical timing uncertainty of approximately 10 hours. In order to improve this critical understanding, a number of NASA missions are being planned. Specifically the Solar Probe Plus and Solar Orbiter missions will investigate the inner Heliospheric evolution of coronal mass ejections and the acceleration and propagation of solar energetic particles. In addition, a number of multi-spacecraft concepts have been studied that have the potential to significantly improve the accuracy of long-term space weather forecasts.

  16. Model Insensitive and Calibration Independent Method for Determination of the Downstream Neutral Hydrogen Density Through Ly-alpha Glow Observations

    Science.gov (United States)

    Gangopadhyay, P.; Judge, D. L.

    1996-01-01

    Our knowledge of the various heliospheric phenomena (location of the solar wind termination shock, heliopause configuration and very local interstellar medium parameters) is limited by uncertainties in the available heliospheric plasma models and by calibration uncertainties in the observing instruments. There is, thus, a strong motivation to develop model insensitive and calibration independent methods to reduce the uncertainties in the relevant heliospheric parameters. We have developed such a method to constrain the downstream neutral hydrogen density inside the heliospheric tail. In our approach we have taken advantage of the relative insensitivity of the downstream neutral hydrogen density profile to the specific plasma model adopted. We have also used the fact that the presence of an asymmetric neutral hydrogen cavity surrounding the sun, characteristic of all neutral densities models, results in a higher multiple scattering contribution to the observed glow in the downstream region than in the upstream region. This allows us to approximate the actual density profile with one which is spatially uniform for the purpose of calculating the downstream backscattered glow. Using different spatially constant density profiles, radiative transfer calculations are performed, and the radial dependence of the predicted glow is compared with the observed I/R dependence of Pioneer 10 UV data. Such a comparison bounds the large distance heliospheric neutral hydrogen density in the downstream direction to a value between 0.05 and 0.1/cc.

  17. Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction

    Directory of Open Access Journals (Sweden)

    I. I. Roussev

    2009-09-01

    Full Text Available We present general considerations regarding the derivation of the radial distances of coronal mass ejections (CMEs from elongation angle measurements such as those provided by SECCHI and SMEI, focusing on measurements in the Heliospheric Imager 2 (HI-2 field of view (i.e. past 0.3 AU. This study is based on a three-dimensional (3-D magneto-hydrodynamics (MHD simulation of two CMEs observed by SECCHI on 24–27 January 2007. Having a 3-D simulation with synthetic HI images, we are able to compare the two basic methods used to derive CME positions from elongation angles, the so-called "Point-P" and "Fixed-φ" approximations. We confirm, following similar works, that both methods, while valid in the most inner heliosphere, yield increasingly large errors in HI-2 field of view for fast and wide CMEs. Using a simple model of a CME as an expanding self-similar sphere, we derive an analytical relationship between elongation angles and radial distances for wide CMEs. This relationship is simply the harmonic mean of the "Point-P" and "Fixed-φ" approximations and it is aimed at complementing 3-D fitting of CMEs by cone models or flux rope shapes. It proves better at getting the kinematics of the simulated CME right when we compare the results of our line-of-sights to the MHD simulation. Based on this approximation, we re-analyze the J-maps (time-elongation maps in 26–27 January 2007 and present the first observational evidence that the merging of CMEs is associated with a momentum exchange from the faster ejection to the slower one due to the propagation of the shock wave associated with the fast eruption through the slow eruption.

  18. Heliospheric current sheet and effects of its interaction with solar cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Malova, H. V., E-mail: hmalova@yandex.ru [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation); Popov, V. Yu.; Grigorenko, E. E.; Dunko, A. V.; Petrukovich, A. A. [Russian Academy of Sciences, Space Research Institute (Russian Federation)

    2016-08-15

    The effects of interaction of solar cosmic rays (SCRs) with the heliospheric current sheet (HCS) in the solar wind are analyzed. A self-consistent kinetic model of the HCS is developed in which ions with quasiadiabatic dynamics can present. The HCS is considered an equilibrium embedded current structure in which two main plasma species with different temperatures (the low-energy background plasma of the solar wind and the higher energy SCR component) contribute to the current. The obtained results are verified by comparing with the results of numerical simulations based on solving equations of motion by the particle tracing method in the given HCS magnetic field with allowance for SCR particles. It is shown that the HCS is a relatively thin multiscale current configuration embedded in a thicker plasma layer. In this case, as a rule, the shear (tangential to the sheet current) component of the magnetic field is present in the HCS. Taking into account high-energy SCR particles in the HCS can lead to a change of its configuration and the formation of a multiscale embedded structure. Parametric family of solutions is considered in which the current balance in the HCS is provided at different SCR temperatures and different densities of the high-energy plasma. The SCR densities are determined at which an appreciable (detectable by satellites) HCS thickening can occur. Possible applications of this modeling to explain experimental observations are discussed.

  19. Comprehensive Assessment of Models and Events based on Library tools (CAMEL)

    Science.gov (United States)

    Rastaetter, L.; Boblitt, J. M.; DeZeeuw, D.; Mays, M. L.; Kuznetsova, M. M.; Wiegand, C.

    2017-12-01

    At the Community Coordinated Modeling Center (CCMC), the assessment of modeling skill using a library of model-data comparison metrics is taken to the next level by fully integrating the ability to request a series of runs with the same model parameters for a list of events. The CAMEL framework initiates and runs a series of selected, pre-defined simulation settings for participating models (e.g., WSA-ENLIL, SWMF-SC+IH for the heliosphere, SWMF-GM, OpenGGCM, LFM, GUMICS for the magnetosphere) and performs post-processing using existing tools for a host of different output parameters. The framework compares the resulting time series data with respective observational data and computes a suite of metrics such as Prediction Efficiency, Root Mean Square Error, Probability of Detection, Probability of False Detection, Heidke Skill Score for each model-data pair. The system then plots scores by event and aggregated over all events for all participating models and run settings. We are building on past experiences with model-data comparisons of magnetosphere and ionosphere model outputs in GEM2008, GEM-CEDAR CETI2010 and Operational Space Weather Model challenges (2010-2013). We can apply the framework also to solar-heliosphere as well as radiation belt models. The CAMEL framework takes advantage of model simulations described with Space Physics Archive Search and Extract (SPASE) metadata and a database backend design developed for a next-generation Run-on-Request system at the CCMC.

  20. Solar Energetic Particle Event Risks for Future Human Missions within the Inner Heliosphere

    Science.gov (United States)

    Over, S.; Ford, J.

    2017-12-01

    As astronauts travel beyond low-Earth orbit (LEO), space weather research will play a key role in determining risks from space radiation. Of interest are the rare, large solar energetic particle (SEP) events that can cause significant medical effects during flight. Historical SEP data were analyzed from the Geostationary Operational Environmental Satellites (GOES) program covering the time period of 1986 to 2016 for SEP events. The SEP event data were combined with a Monte Carlo approach to develop a risk model to determine maximum expected doses for missions within the inner heliosphere. Presented here are results from risk assessments for proposed Mars transits as compared to a geostationary Earth-bound mission. Overall, the greatest risk was for the return from Mars with a Venus swing-by, due to the additional transit length and decreased distance from the Sun as compared to traditional Hohmann transfers. The overall results do not indicate that the effects of SEP events alone would prohibit these missions based on current radiation limits alone, but the combination of doses from SEP events and galactic cosmic radiation may be significant, and should be considered in all phases of mission design.

  1. On the Effects of Pickup Ion-driven Waves on the Diffusion Tensor of Low-energy Electrons in the Heliosphere

    Energy Technology Data Exchange (ETDEWEB)

    Engelbrecht, N. Eugene, E-mail: n.eugene.engelbrecht@gmail.com [Center for Space Research, North-West University, Potchefstroom, 2522 (South Africa)

    2017-11-01

    The effects of Alfvén cyclotron waves generated due to the formation in the outer heliosphere of pickup ions on the transport coefficients of low-energy electrons is investigated here. To this end, parallel mean free path (MFP) expressions are derived from quasilinear theory, employing the damping model of dynamical turbulence. These are then used as inputs for existing expressions for the perpendicular MFP and turbulence-reduced drift coefficient. Using outputs generated by a two-component turbulence transport model, the resulting diffusion coefficients are compared with those derived using a more typically assumed turbulence spectral form, which neglects the effects of pickup ion-generated waves. It is found that the inclusion of pickup ion effects greatly leads to considerable reductions in the parallel and perpendicular MFPs of 1–10 MeV electrons beyond ∼10 au, which are argued to have significant consequences for studies of the transport of these particles.

  2. Effects of Turbulent Magnetic Fields on the Transport and Acceleration of Energetic Charged Particles: Numerical Simulations with Application to Heliospheric Physics

    Science.gov (United States)

    Guo, Fan

    2012-11-01

    Turbulent magnetic fields are ubiquitous in space physics and astrophysics. The influence of magnetic turbulence on the motions of charged particles contains the essential physics of the transport and acceleration of energetic charged particles in the heliosphere, which is to be explored in this thesis. After a brief introduction on the energetic charged particles and magnetic fields in the heliosphere, the rest of this dissertation focuses on three specific topics: 1. the transport of energetic charged particles in the inner heliosphere, 2. the acceleration of ions at collisionless shocks, and 3. the acceleration of electrons at collisionless shocks. We utilize various numerical techniques to study these topics. In Chapter 2 we study the propagation of charged particles in turbulent magnetic fields similar to the propagation of solar energetic particles in the inner heliosphere. The trajectories of energetic charged particles in the turbulent magnetic field are numerically integrated. The turbulence model includes a Kolmogorov-like magnetic field power spectrum containing a broad range of scales from those that lead to large-scale field-line random walk to small scales leading to resonant pitch-angle scattering of energetic particles. We show that small-scale variations in particle intensities (the so-called "dropouts") and velocity dispersions observed by spacecraft can be reproduced using this method. Our study gives a new constraint on the error of "onset analysis", which is a technique commonly used to infer information about the initial release of energetic particles. We also find that the dropouts are rarely produced in the simulations using the so-called "two-component" magnetic turbulence model (Matthaeus et al., 1990). The result questions the validity of this model in studying particle transport. In the first part of Chapter 3 we study the acceleration of ions in the existence of turbulent magnetic fields. We use 3-D self-consistent hybrid simulations

  3. Solar wind temperature observations in the outer heliosphere

    Science.gov (United States)

    Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

    1992-01-01

    The Pioneer 10, Pioneer 11, and Voyager 2 spacecraft are now at heliocentric distances of 50, 32 and 33 AU, and heliographic latitudes of 3.5 deg N, 17 deg N, and 0 deg N, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer l0 is on the opposite side of the sun. The baselines defined by these spacecraft make it possible to resolve radial, longitudinal, and latitudinal variations of solar wind parameters. The solar wind temperature decreases with increasing heliocentric distance out to a distance of 10-15 AU. At larger heliocentric distances, this gradient disappears. These high solar wind temperatures in the outer heliosphere have persisted for at least 10 years, which suggests that they are not a solar cycle effect. The solar wind temperature varied with heliographic latitude during the most recent solar minimum. The solar wind temperature at Pioneer 11 and Voyager 2 was higher than that seen at Pioneer 10 for an extended period of time, which suggests the existence of a large-scale variation of temperature with celestial longitude, but the contribution of transient phenomena is yet to be clarified.

  4. Heliospheric MeV energization due to resonant interaction

    International Nuclear Information System (INIS)

    Roth, Ilan

    2001-01-01

    The prompt enhancement of relativistic electron flux during active geomagnetic periods, and the impulsive increase in the flux of the heliospheric energetic heavy ions during active solar periods are of major importance with respect to the proper operation of electronics on space-borne spacecraft and the safety of interplanetary human travel, respectively. Both enhancements may be caused by resonant wave-particle interaction with oblique electromagnetic waves on the terrestrial and coronal field lines. Whistler waves, which are enhanced significantly during substorms and which propagate obliquely to the magnetic field, can interact with energetic electrons through Landau, cyclotron, and higher harmonic resonant interactions when the Doppler-shifted wave frequency equals any (positive or negative) integer multiple of the local relativistic gyrofrequency. This interaction occurs over a broad spatial region when a relativistic electron is bouncing in the terrestrial magnetic field. Coronal ions interact selectively with electromagnetic ion-cyclotron (emic) waves which are correlated with impulsive flares. This interaction occurs over a small spatial region when the Doppler-shifted frequency matches the first or higher harmonic of the ion gyrofrequency. Recent new observations of terrestrial MeV X-rays are interpreted as a resonant loss of the radiation belt electrons

  5. A propagation tool to connect remote-sensing observations with in-situ measurements of heliospheric structures

    Science.gov (United States)

    Rouillard, A. P.; Lavraud, B.; Génot, V.; Bouchemit, M.; Dufourg, N.; Plotnikov, I.; Pinto, R. F.; Sanchez-Diaz, E.; Lavarra, M.; Penou, M.; Jacquey, C.; André, N.; Caussarieu, S.; Toniutti, J.-P.; Popescu, D.; Buchlin, E.; Caminade, S.; Alingery, P.; Davies, J. A.; Odstrcil, D.; Mays, L.

    2017-11-01

    The remoteness of the Sun and the harsh conditions prevailing in the solar corona have so far limited the observational data used in the study of solar physics to remote-sensing observations taken either from the ground or from space. In contrast, the 'solar wind laboratory' is directly measured in situ by a fleet of spacecraft measuring the properties of the plasma and magnetic fields at specific points in space. Since 2007, the solar-terrestrial relations observatory (STEREO) has been providing images of the solar wind that flows between the solar corona and spacecraft making in-situ measurements. This has allowed scientists to directly connect processes imaged near the Sun with the subsequent effects measured in the solar wind. This new capability prompted the development of a series of tools and techniques to track heliospheric structures through space. This article presents one of these tools, a web-based interface called the 'Propagation Tool' that offers an integrated research environment to study the evolution of coronal and solar wind structures, such as Coronal Mass Ejections (CMEs), Corotating Interaction Regions (CIRs) and Solar Energetic Particles (SEPs). These structures can be propagated from the Sun outwards to or alternatively inwards from planets and spacecraft situated in the inner and outer heliosphere. In this paper, we present the global architecture of the tool, discuss some of the assumptions made to simulate the evolution of the structures and show how the tool connects to different databases.

  6. Inner heliosphere spatial gradients of GCR protons and alpha particles in the low GeV range

    Science.gov (United States)

    Gieseler, J.; Boezio, M.; Casolino, M.; De Simone, N.; Di Felice, V.; Heber, B.; Martucci, M.; Picozza, P.

    2013-12-01

    The spacecraft Ulysses was launched in October 1990 in the maximum phase of solar cycle 22, reached its final, highly inclined (80.2°) Keplerian orbit around the Sun in February 1992, and was finally switched off in June 2009. The Kiel Electron Telescope (KET) aboard Ulysses measures electrons from 3 MeV to a few GeV and protons and helium in the energy range from 6 MeV/nucleon to above 2 GeV/nucleon. In order to investigate the radial and latitudinal gradients of galactic cosmic rays (GCR), it is essential to know their intensity variations for a stationary observer in the heliosphere because the Ulysses measurements reflect not only the spatial but also the temporal variation of the energetic particle intensities. This was accomplished in the past with the Interplanetary Monitoring Platform-J (IMP 8) until it was lost in 2006. Fortunately, the satellite-borne experiment PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) was launched in June 2006 and can be used as a reliable 1 AU baseline for measurements of the KET aboard Ulysses. With these tools at hand, we have the opportunity to determine the spatial gradients of GCR protons and alpha particles at about 0.1 to 1 GeV/n in the inner heliosphere during the extended minimum of solar cycle 23. We then compare these A0 cycle.

  7. Modeling the Variable Heliopause Location

    Science.gov (United States)

    Hensley, Kerry

    2018-03-01

    In 2012, Voyager 1 zipped across the heliopause. Five and a half years later, Voyager 2 still hasnt followed its twin into interstellar space. Can models of the heliopause location help determine why?How Far to the Heliopause?Artists conception of the heliosphere with the important structures and boundaries labeled. [NASA/Goddard/Walt Feimer]As our solar system travels through the galaxy, the solar outflow pushes against the surrounding interstellar medium, forming a bubble called the heliosphere. The edge of this bubble, the heliopause, is the outermost boundary of our solar system, where the solar wind and the interstellar medium meet. Since the solar outflow is highly variable, the heliopause is constantly moving with the motion driven by changes inthe Sun.NASAs twin Voyager spacecraft were poisedto cross the heliopause after completingtheir tour of the outer planets in the 1980s. In 2012, Voyager 1 registered a sharp increase in the density of interstellar particles, indicating that the spacecraft had passed out of the heliosphere and into the interstellar medium. The slower-moving Voyager 2 was set to pierce the heliopause along a different trajectory, but so far no measurements have shown that the spacecraft has bid farewell to oursolar system.In a recent study, ateam of scientists led by Haruichi Washimi (Kyushu University, Japan and CSPAR, University of Alabama-Huntsville) argues that models of the heliosphere can help explain this behavior. Because the heliopause location is controlled by factors that vary on many spatial and temporal scales, Washimiand collaborators turn to three-dimensional, time-dependent magnetohydrodynamics simulations of the heliosphere. In particular, they investigate how the position of the heliopause along the trajectories of Voyager 1 and Voyager 2 changes over time.Modeled location of the heliopause along the paths of Voyagers 1 (blue) and 2 (orange). Click for a closer look. The red star indicates the location at which Voyager

  8. A GENERALIZED DIFFUSION TENSOR FOR FULLY ANISOTROPIC DIFFUSION OF ENERGETIC PARTICLES IN THE HELIOSPHERIC MAGNETIC FIELD

    International Nuclear Information System (INIS)

    Effenberger, F.; Fichtner, H.; Scherer, K.; Barra, S.; Kleimann, J.; Strauss, R. D.

    2012-01-01

    The spatial diffusion of cosmic rays in turbulent magnetic fields can, in the most general case, be fully anisotropic, i.e., one has to distinguish three diffusion axes in a local, field-aligned frame. We reexamine the transformation for the diffusion tensor from this local to a global frame, in which the Parker transport equation for energetic particles is usually formulated and solved. Particularly, we generalize the transformation formulae to allow for an explicit choice of two principal local perpendicular diffusion axes. This generalization includes the 'traditional' diffusion tensor in the special case of isotropic perpendicular diffusion. For the local frame, we describe the motivation for the choice of the Frenet-Serret trihedron, which is related to the intrinsic magnetic field geometry. We directly compare the old and the new tensor elements for two heliospheric magnetic field configurations, namely the hybrid Fisk and Parker fields. Subsequently, we examine the significance of the different formulations for the diffusion tensor in a standard three-dimensional model for the modulation of galactic protons. For this, we utilize a numerical code to evaluate a system of stochastic differential equations equivalent to the Parker transport equation and present the resulting modulated spectra. The computed differential fluxes based on the new tensor formulation deviate from those obtained with the 'traditional' one (only valid for isotropic perpendicular diffusion) by up to 60% for energies below a few hundred MeV depending on heliocentric distance.

  9. A three-coordinate system (ecliptic, galactic, ISMF) spectral analysis of heliospheric ENA emissions using CASSINI/INCA measurements

    International Nuclear Information System (INIS)

    Dialynas, K.; Krimigis, S. M.; Mitchell, D. G.; Roelof, E. C.; Decker, R. B

    2013-01-01

    In the present study, we use all-sky energy-resolved energetic neutral atom (ENA) maps obtained by the Ion and Neutral CAmera (INCA) instrument on board Cassini that correspond to the time period from 2003 to 2009, in four discrete energy passbands (∼5.4 to ∼55 keV), to investigate the geometrical characteristics of the belt (a broad band of emission in the sky). The heliospheric ENA emissions are mapped in three different coordinate systems (ecliptic, Galactic, and interstellar magnetic field (ISMF)), and spectral analyses are performed to further examine the belt's possible energy dependence. Our conclusions are summarized as follows: (1) the high flux ENA belt identified in the energy range of 8-42 keV is moderately well organized in Galactic coordinates, as the ENA minima appear in the vicinity of the north and south Galactic poles; (2) using minimization criteria ( B · R ∼ 0), the deviation of the ENA emissions from the equator is effectively minimized in a rotated frame, which we interpret as ISMF, where its north pole points toward 190° ecliptic longitude and 15° ecliptic latitude; (3) ENA spectra show a power-law form in energy that can be fitted with a single function presenting higher spectral slopes in the belt region and lower outside (3.4 < γ < 4.4); (4) the spectra are almost indistinguishable between the tail and the nose regions, i.e., no noticeable asymmetry is observed; (5) the consistency of the ENA distributions as a function of latitude among the different INCA channels indicates that the morphology of the belt (peak, width, and structure) is nearly energy independent from 8 keV to 30 keV (minor deviations start to appear at >35 keV); and (6) in the low count rate regions, the long-term ENA count rate profiles do not match the measured cosmic ray profiles, indicating that even the minimum ENA emissions detected by INCA are foreground ENAs.

  10. ASYMMETRIC SUNSPOT ACTIVITY AND THE SOUTHWARD DISPLACEMENT OF THE HELIOSPHERIC CURRENT SHEET

    International Nuclear Information System (INIS)

    Wang, Y.-M.; Robbrecht, E.

    2011-01-01

    Observations of the interplanetary magnetic field (IMF) have suggested a statistical tendency for the heliospheric current sheet (HCS) to be shifted a few degrees southward of the heliographic equator during the period 1965-2010, particularly in the years near sunspot minimum. Using potential-field source-surface extrapolations and photospheric flux-transport simulations, we demonstrate that this southward displacement follows from Joy's law and the observed hemispheric asymmetry in the sunspot numbers, with activity being stronger in the southern (northern) hemisphere during the declining (rising) phase of cycles 20-23. The hemispheric asymmetry gives rise to an axisymmetric quadrupole field, whose equatorial zone has the sign of the leading-polarity flux in the dominant hemisphere; during the last four cycles, the polarity of the IMF around the equator thus tended to match that of the north polar field both before and after polar field reversal. However, large fluctuations are introduced by the nonaxisymmetric field components, which depend on the longitudinal distribution of sunspot activity in either hemisphere. Consistent with this model, the HCS showed an average northward displacement during cycle 19, when the 'usual' alternation was reversed and the northern hemisphere became far more active than the southern hemisphere during the declining phase of the cycle. We propose a new method for determining the north-south displacement of the HCS from coronal streamer observations.

  11. PREDICTION OF GEOMAGNETIC STORM STRENGTH FROM INNER HELIOSPHERIC IN SITU OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kubicka, M.; Möstl, C.; Amerstorfer, T.; Boakes, P. D.; Törmänen, O. [Space Research Institute, Austrian Academy of Sciences, 8042 Graz (Austria); Feng, L. [Purple Mountain Observatory, Chinese Academy of Sciences, West Beijing Road 2 Nanjing, 210008 (China); Eastwood, J. P., E-mail: christian.moestl@oeaw.ac.at [Space and Atmospheric Physics, The Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-12-20

    Prediction of the effects of coronal mass ejections (CMEs) on Earth strongly depends on knowledge of the interplanetary magnetic field southward component, B{sub z}. Predicting the strength and duration of B{sub z} inside a CME with sufficient accuracy is currently impossible, forming the so-called B{sub z} problem. Here, we provide a proof-of-concept of a new method for predicting the CME arrival time, speed, B{sub z}, and resulting disturbance storm time ( Dst ) index on Earth based only on magnetic field data, measured in situ in the inner heliosphere (<1 au). On 2012 June 12–16, three approximately Earthward-directed and interacting CMEs were observed by the Solar Terrestrial Relations Observatory imagers and Venus Express (VEX) in situ at 0.72 au, 6° away from the Sun–Earth line. The CME kinematics are calculated using the drag-based and WSA–Enlil models, constrained by the arrival time at VEX , resulting in the CME arrival time and speed on Earth. The CME magnetic field strength is scaled with a power law from VEX to Wind . Our investigation shows promising results for the Dst forecast (predicted: −96 and −114 nT (from 2 Dst models); observed: −71 nT), for the arrival speed (predicted: 531 ± 23 km s{sup −1}; observed: 488 ± 30 km s{sup −1}), and for the timing (6 ± 1 hr after the actual arrival time). The prediction lead time is 21 hr. The method may be applied to vector magnetic field data from a spacecraft at an artificial Lagrange point between the Sun and Earth or to data taken by any spacecraft temporarily crossing the Sun–Earth line.

  12. Badhwar-O'Neill 2011 Galactic Cosmic Ray Model Update and Future Improvements

    Science.gov (United States)

    O'Neill, Pat M.; Kim, Myung-Hee Y.

    2014-01-01

    The Badhwar-O'Neill Galactic Cosmic Ray (GCR) Model based on actual GR measurements is used by deep space mission planners for the certification of micro-electronic systems and the analysis of radiation health risks to astronauts in space missions. The BO GCR Model provides GCR flux in deep space (outside the earth's magnetosphere) for any given time from 1645 to present. The energy spectrum from 50 MeV/n-20 GeV/n is provided for ions from hydrogen to uranium. This work describes the most recent version of the BO GCR model (BO'11). BO'11 determines the GCR flux at a given time applying an empirical time delay function to past sunspot activity. We describe the GCR measurement data used in the BO'11 update - modern data from BESS, PAMELA, CAPRICE, and ACE emphasized for than the older balloon data used for the previous BO model (BO'10). We look at the GCR flux for the last 24 solar minima and show how much greater the flux was for the cycle 24 minimum in 2010. The BO'11 Model uses the traditional, steady-state Fokker-Planck differential equation to account for particle transport in the heliosphere due to diffusion, convection, and adiabatic deceleration. It assumes a radially symmetrical diffusion coefficient derived from magnetic disturbances caused by sunspots carried onward by a constant solar wind. A more complex differential equation is now being tested to account for particle transport in the heliosphere in the next generation BO model. This new model is time-dependent (no longer a steady state model). In the new model, the dynamics and anti-symmetrical features of the actual heliosphere are accounted for so empirical time delay functions will no longer be required. The new model will be capable of simulating the more subtle features of modulation - such as the Sun's polarity and modulation dependence on the gradient and curvature drift. This improvement is expected to significantly improve the fidelity of the BO GCR model. Preliminary results of its

  13. Oscillations in the open solar magnetic flux with a period of 1.68 years: imprint on galactic cosmic rays and implications for heliospheric shielding

    Directory of Open Access Journals (Sweden)

    A. Rouillard

    2004-12-01

    Full Text Available An understanding of how the heliosphere modulates galactic cosmic ray (GCR fluxes and spectra is important, not only for studies of their origin, acceleration and propagation in our galaxy, but also for predicting their effects (on technology and on the Earth's environment and organisms and for interpreting abundances of cosmogenic isotopes in meteorites and terrestrial reservoirs. In contrast to the early interplanetary measurements, there is growing evidence for a dominant role in GCR shielding of the total open magnetic flux, which emerges from the solar atmosphere and enters the heliosphere. In this paper, we relate a strong 1.68-year oscillation in GCR fluxes to a corresponding oscillation in the open solar magnetic flux and infer cosmic-ray propagation paths confirming the predictions of theories in which drift is important in modulating the cosmic ray flux. Key words. Interplanetary physics (Cosmic rays, Interplanetary magnetic fields

  14. Modelling cosmic ray intensities along the Ulysses trajectory

    Directory of Open Access Journals (Sweden)

    D. C. Ndiitwani

    2005-03-01

    Full Text Available Time dependent cosmic ray modulation in the inner heliosphere is studied by comparing results from a 2-D, time-dependent cosmic ray transport model with Ulysses observations. A compound approach, which combines the effects of the global changes in the heliospheric magnetic field magnitude with drifts to establish a realistic time-dependence, in the diffusion and drift coefficients, are used. We show that this model results in realistic cosmic ray modulation from the Ulysses launch (1990 until recently (2004 when compared to 2.5-GV electron and proton and 1.2-GV electron and Helium observations from this spacecraft. This approach is also applied to compute radial gradients present in 2.5-GV cosmic ray electron and protons in the inner heliosphere. The observed latitude dependence for both positive and negative charged particles during both the fast latitude scan periods, corresponding to different solar activity conditions, could also be realistically computed. For this an additional reduction in particle drifts (compared to diffusion toward solar maximum is needed. This results in a realistic charge-sign dependent modulation at solar maximum and the model is also applied to predict charge-sign dependent modulation up to the next expected solar minimum.

  15. SHOCK CONNECTIVITY IN THE 2010 AUGUST AND 2012 JULY SOLAR ENERGETIC PARTICLE EVENTS INFERRED FROM OBSERVATIONS AND ENLIL MODELING

    International Nuclear Information System (INIS)

    Bain, H. M.; Luhmann, J. G.; Li, Y.; Mays, M. L.; Jian, L. K.; Odstrcil, D.

    2016-01-01

    During periods of increased solar activity, coronal mass ejections (CMEs) can occur in close succession and proximity to one another. This can lead to the interaction and merger of CME ejecta as they propagate in the heliosphere. The particles accelerated in these shocks can result in complex solar energetic particle (SEP) events, as observing spacecraft form both remote and local shock connections. It can be challenging to understand these complex SEP events from in situ profiles alone. Multipoint observations of CMEs in the near-Sun environment, from the Solar Terrestrial Relations Observatory –Sun Earth Connection Coronal and Heliospheric Investigation and the Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph, greatly improve our chances of identifying the origin of these accelerated particles. However, contextual information on conditions in the heliosphere, including the background solar wind conditions and shock structures, is essential for understanding SEP properties well enough to forecast their characteristics. Wang–Sheeley–Arge WSA-ENLIL + Cone modeling provides a tool to interpret major SEP event periods in the context of a realistic heliospheric model and to determine how much of what is observed in large SEP events depends on nonlocal magnetic connections to shock sources. We discuss observations of the SEP-rich periods of 2010 August and 2012 July in conjunction with ENLIL modeling. We find that much SEP activity can only be understood in the light of such models, and in particular from knowing about both remote and local shock source connections. These results must be folded into the investigations of the physics underlying the longitudinal extent of SEP events, and the source connection versus diffusion pictures of interpretations of SEP events.

  16. SHOCK CONNECTIVITY IN THE 2010 AUGUST AND 2012 JULY SOLAR ENERGETIC PARTICLE EVENTS INFERRED FROM OBSERVATIONS AND ENLIL MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Bain, H. M.; Luhmann, J. G.; Li, Y. [Space Sciences Laboratory, UC Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Mays, M. L. [Catholic University of America, Washington, DC (United States); Jian, L. K.; Odstrcil, D., E-mail: hbain@ssl.berkeley.edu [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2016-07-01

    During periods of increased solar activity, coronal mass ejections (CMEs) can occur in close succession and proximity to one another. This can lead to the interaction and merger of CME ejecta as they propagate in the heliosphere. The particles accelerated in these shocks can result in complex solar energetic particle (SEP) events, as observing spacecraft form both remote and local shock connections. It can be challenging to understand these complex SEP events from in situ profiles alone. Multipoint observations of CMEs in the near-Sun environment, from the Solar Terrestrial Relations Observatory –Sun Earth Connection Coronal and Heliospheric Investigation and the Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph, greatly improve our chances of identifying the origin of these accelerated particles. However, contextual information on conditions in the heliosphere, including the background solar wind conditions and shock structures, is essential for understanding SEP properties well enough to forecast their characteristics. Wang–Sheeley–Arge WSA-ENLIL + Cone modeling provides a tool to interpret major SEP event periods in the context of a realistic heliospheric model and to determine how much of what is observed in large SEP events depends on nonlocal magnetic connections to shock sources. We discuss observations of the SEP-rich periods of 2010 August and 2012 July in conjunction with ENLIL modeling. We find that much SEP activity can only be understood in the light of such models, and in particular from knowing about both remote and local shock source connections. These results must be folded into the investigations of the physics underlying the longitudinal extent of SEP events, and the source connection versus diffusion pictures of interpretations of SEP events.

  17. Solution of Heliospheric Propagation: Unveiling the Local Interstellar Spectra of Cosmic-ray Species

    Energy Technology Data Exchange (ETDEWEB)

    Boschini, M. J.; Torre, S. Della; Gervasi, M.; Grandi, D.; Vacca, G. La; Pensotti, S.; Rancoita, P. G.; Rozza, D.; Tacconi, M. [INFN, Milano-Bicocca, Milano (Italy); Jóhannesson, G. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Kachelriess, M. [Institutt for fysikk, NTNU, NO-7491 Trondheim (Norway); Masi, N.; Quadrani, L. [INFN, Bologna (Italy); Moskalenko, I. V.; Orlando, E.; Porter, T. A. [Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Ostapchenko, S. S. [Frankfurt Institute of Advanced Studies, Frankfurt (Germany)

    2017-05-10

    Local interstellar spectra (LIS) for protons, helium, and antiprotons are built using the most recent experimental results combined with state-of-the-art models for propagation in the Galaxy and heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of cosmic-ray (CR) species at different modulation levels and at both polarities of the solar magnetic field. To do so in a self-consistent way, an iterative procedure was developed, where the GALPROP LIS output is fed into HelMod, providing modulated spectra for specific time periods of selected experiments to compare with the data; the HelMod parameter optimization is performed at this stage and looped back to adjust the LIS using the new GALPROP run. The parameters were tuned with the maximum likelihood procedure using an extensive data set of proton spectra from 1997 to 2015. The proposed LIS accommodate both the low-energy interstellar CR spectra measured by Voyager 1 and the high-energy observations by BESS, Pamela, AMS-01, and AMS-02 made from the balloons and near-Earth payloads; it also accounts for Ulysses counting rate features measured out of the ecliptic plane. The found solution is in a good agreement with proton, helium, and antiproton data by AMS-02, BESS, and PAMELA in the whole energy range.

  18. Optimizing Global Coronal Magnetic Field Models Using Image-Based Constraints

    Science.gov (United States)

    Jones-Mecholsky, Shaela I.; Davila, Joseph M.; Uritskiy, Vadim

    2016-01-01

    The coronal magnetic field directly or indirectly affects a majority of the phenomena studied in the heliosphere. It provides energy for coronal heating, controls the release of coronal mass ejections, and drives heliospheric and magnetospheric activity, yet the coronal magnetic field itself has proven difficult to measure. This difficulty has prompted a decades-long effort to develop accurate, timely, models of the field, an effort that continues today. We have developed a method for improving global coronal magnetic field models by incorporating the type of morphological constraints that could be derived from coronal images. Here we report promising initial tests of this approach on two theoretical problems, and discuss opportunities for application.

  19. New Measurements of Suprathermal Ions, Energetic Particles, and Cosmic Rays in the Outer Heliosphere from the New Horizons PEPSSI Instrument

    Science.gov (United States)

    Hill, M. E.; Kollmann, P.; McNutt, R. L., Jr.; Stern, A.; Weaver, H. A., Jr.; Young, L. A.; Olkin, C.; Spencer, J. R.

    2017-12-01

    During the period from January 2012 to December 2017 the New Horizons spacecraft traveled from 22 to 41 AU from the Sun, making nearly continuous interplanetary plasma and particle measurements utilizing the SWAP and PEPSSI instruments. We report on newly extended measurements from PEPSSI (Pluto Energetic Particle Spectrometer Science Investigation) that now bring together suprathermal particles above 2 keV/nuc (including interstellar pickup ions), energetic particles with H, He, and O composition from 30 keV to 1 MeV, and cosmic rays above 65 MeV (with effective count-rate-limited upper energy of 1 GeV). Such a wide energy range allows us to look at the solar wind structures passing over the spacecraft, the energetic particles that are often accelerated by these structures, and the suppression of cosmic rays resulting from the increased turbulence inhibiting cosmic ray transport to the spacecraft position (i.e., Forbush decreases). This broad perspective provides simultaneous, previously unattainable diagnostics of outer heliospheric particle dynamics and acceleration. Besides the benefit of being recent, in-ecliptic measurements, unlike the historic Voyager 1 and 2 spacecraft, these PEPSSI observations are also totally unique in the suprathermal range; in this region only PEPSSI can span the suprathermal range, detecting a population that is a linchpin to understanding the outer heliosphere.

  20. Using Science Data and Models for Space Weather Forecasting - Challenges and Opportunities

    Science.gov (United States)

    Hesse, Michael; Pulkkinen, Antti; Zheng, Yihua; Maddox, Marlo; Berrios, David; Taktakishvili, Sandro; Kuznetsova, Masha; Chulaki, Anna; Lee, Hyesook; Mullinix, Rick; hide

    2012-01-01

    Space research, and, consequently, space weather forecasting are immature disciplines. Scientific knowledge is accumulated frequently, which changes our understanding or how solar eruptions occur, and of how they impact targets near or on the Earth, or targets throughout the heliosphere. Along with continuous progress in understanding, space research and forecasting models are advancing rapidly in capability, often providing substantially increases in space weather value over time scales of less than a year. Furthermore, the majority of space environment information available today is, particularly in the solar and heliospheric domains, derived from research missions. An optimal forecasting environment needs to be flexible enough to benefit from this rapid development, and flexible enough to adapt to evolving data sources, many of which may also stem from non-US entities. This presentation will analyze the experiences obtained by developing and operating both a forecasting service for NASA, and an experimental forecasting system for Geomagnetically Induced Currents.

  1. THE PRODUCTION OF LOW-ENERGY NEUTRONS IN SOLAR FLARES AND THE IMPORTANCE OF THEIR DETECTION IN THE INNER HELIOSPHERE

    International Nuclear Information System (INIS)

    Murphy, R. J.; Kozlovsky, B.; Share, G. H.

    2012-01-01

    Neutron detectors on spacecraft in the inner heliosphere can observe the low-energy ( ion –1 ) most important for producing low-energy neutrons from these reactions. We calculate escaping-neutron spectra and neutron-capture line yields from ions propagating in a magnetic loop with various kinetic-energy spectra. This study provides the basis for planning inner-heliospheric missions having a low-energy neutron detector. The MESSENGER spacecraft orbiting Mercury has such a detector. We conclude that a full understanding of ion acceleration, transport, and interaction at the Sun requires observation of both neutrons and gamma rays with detectors of comparable sensitivity. We find that the neutron-capture line fluence at 1 AU is comparable to the 1-10 MeV neutron fluence at 0.5 AU, and therefore as effective for revealing low-energy ion acceleration. However, as the distance from the Sun to the neutron detector decreases, the tremendous increase of the low-energy neutron flux allows exploration of ion acceleration in weak flares not previously observable and may reveal acceleration at other sites not previously detected where low-energy neutrons could be the only high-energy signature of ion acceleration. Also, a measurement of the low-energy neutron spectrum will provide important information about the accelerated-ion spectrum that is not available from the capture line fluence measurement alone.

  2. TRACKING THE SOLAR CYCLE THROUGH IBEX OBSERVATIONS OF ENERGETIC NEUTRAL ATOM FLUX VARIATIONS AT THE HELIOSPHERIC POLES

    Energy Technology Data Exchange (ETDEWEB)

    Reisenfeld, D. B.; Janzen, P. H. [University of Montana, Missoula, MT 59812 (United States); Bzowski, M., E-mail: dan.reisenfeld@umontana.edu, E-mail: paul.janzen@umontana.edu, E-mail: bzowski@cbk.waw.pl [Space Research Centre of the Polish Academy of Sciences, (CBK PAN), Bartycka 18A, 00-716, Warsaw (Poland); and others

    2016-12-20

    With seven years of Interstellar Boundary Explorer ( IBEX ) observations, from 2009 to 2015, we can now trace the time evolution of heliospheric energetic neutral atoms (ENAs) through over half a solar cycle. At the north and south ecliptic poles, the spacecraft attitude allows for continuous coverage of the ENA flux; thus, signal from these regions has much higher statistical accuracy and time resolution than anywhere else in the sky. By comparing the solar wind dynamic pressure measured at 1 au with the heliosheath plasma pressure derived from the observed ENA fluxes, we show that the heliosheath pressure measured at the poles correlates well with the solar cycle. The analysis requires time-shifting the ENA measurements to account for the travel time out and back from the heliosheath, which allows us to estimate the scale size of the heliosphere in the polar directions. We arrive at an estimated distance to the center of the ENA source region in the north of 220 au and in the south a distance of 190 au. We also find a good correlation between the solar cycle and the ENA energy spectra at the poles. In particular, the ENA flux for the highest IBEX energy channel (4.3 keV) is quite closely correlated with the areas of the polar coronal holes, in both the north and south, consistent with the notion that polar ENAs at this energy originate from pickup ions of the very high speed wind (∼700 km s{sup −1}) that emanates from polar coronal holes.

  3. Heliospheric Modulation of Galactic Cosmic Rays; Diurnal Variability Abstract Details

    Science.gov (United States)

    Kalu, D. F.; Okpala, K. C.

    2017-12-01

    We have studied the variability of Cosmic rays flux during solar quiet days at mid and high latitudes in the Northern Hemisphere. By using the five (5) quietest days for each month and the five disturbed days for each month, the monthly mean diurnal variation of cosmic ray anisotropy have been derived for the period 1999-2015, which covers part of cycles 23, and cycle 24. This study seeks to understand the heliospheric contribution to the variation of these Cosmic rays on quietest days, three stations (Inuvik, Moscow, Rome) Neutron Monitors were employed. This study seeks to understand the important features of the high latitude and mid latitude diurnal wave, and how solar and geomagnetic activity may be influencing the wave characteristics. Cosmic ray wave characteristics were obtained by discrete Fourier transform (DFT). The mean, diurnal amplitude, phase and dispersion for each month's diurnal wave were calculated and profiled. There was clear indication that the terrestrial effect on the variability of the monthly mean was more associated with geomagnetic activity rather than rigidity of the cosmic rays. Correlation of the time series of these wave characteristic with solar and geomagnetic activity index showed better association with solar activity.

  4. Achieving fast reconnection in resistive MHD models via turbulent means

    Directory of Open Access Journals (Sweden)

    G. Lapenta

    2012-04-01

    Full Text Available Astrophysical fluids are generally turbulent and this preexisting turbulence must be taken into account for models of magnetic reconnection in astrophysical, solar or heliospheric environments. In addition, reconnection itself induces turbulence which provides an important feedback on the reconnection process. In this paper we discuss both the theoretical model and numerical evidence that magnetic reconnection becomes fast in the approximation of resistive MHD. We consider the relation between the Lazarian and Vishniac turbulent reconnection theory and Lapenta's numerical experiments testifying of the spontaneous onset of turbulent reconnection in systems which are initially laminar.

  5. Solar wind conditions in the outer heliosphere and the distance to the termination shock

    Science.gov (United States)

    Belcher, John W.; Lazarus, Alan J.; Mcnutt, Ralph L., Jr.; Gordon, George S., Jr.

    1993-01-01

    The Plasma Science experiment on the Voyager 2 spacecraft has measured the properties of solar wind protons from 1 to 40.4 AU. We use these observations to discuss the probable location and motion of the termination shock of the solar wind. Assuming that the interstellar pressure is due to a 5 micro-G magnetic field draped over the upstream face of the heliopause, the radial variation of ram pressure implies that the termination shock will be located at an average distance near 89 AU. This distance scales inversely as the assumed field strength. There are also large variations in ram pressure on time scales of tens of days, due primarily to large variations in solar wind density at a given radius. Such rapid changes in the solar wind ram pressure can cause large perturbations in the location of the termination shock. We study the nonequilibrium location of the termination shock as it responds to these ram pressure changes. The results of this study suggest that the position of the termination shock can vary by as much as 10 AU in a single year, depending on the nature of variations in the ram pressure, and that multiple crossings of the termination shock by a given outer heliosphere spacecraft are likely. After the first crossing, such models of shock motion will be useful for predicting the timing of subsequent crossings.

  6. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution

    Science.gov (United States)

    Lockwood, Mike; Owens, Mathew J.; Imber, Suzanne M.; James, Matthew K.; Bunce, Emma J.; Yeoman, Timothy K.

    2017-06-01

    Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25.type="synopsis">type="main">Plain Language SummaryThere is growing interest in being able to predict the evolution in solar conditions on a better basis than past experience, which is necessarily limited. Two of the key features of the solar magnetic cycle are that the polar fields reverse just after the peak of each sunspot cycle and that the polar field that has accumulated by the time of each sunspot minimum is a good

  7. Particle acceleration at corotating interaction regions in the three-dimensional heliosphere

    International Nuclear Information System (INIS)

    Desai, M.I.; Marsden, R.G.; Sanderson, T.R.; Balogh, A.; Forsyth, R.J.; Gosling, J.T.

    1998-01-01

    We have investigated the relationship between the energetic (∼1MeV) proton intensity (J) and the magnetic compression ratio (C) measured at the trailing edges of corotating interaction regions observed at Ulysses. In general, our results show that the proton intensity was well correlated with the compression ratio, provided that the seed intensity remained constant, consistent with predictions of the Fermi model. Specifically, our results indicate that particles were accelerated to above ∼1MeV in energy at or near the trailing edges of the compression regions observed in the midlatitude southern heliosphere, irrespective of whether the bounding reverse shocks were present or not. On the basis of this, we conclude that shock acceleration is probably not the only mechanism by which particles are accelerated to above ∼1MeV in energy at compression or interaction regions (CIRs). On the basis of magnetic field measurements obtained near the trailing edges of several midlatitude CIRs, we propose that particles could have been accelerated via the Fermi mechanism by being scattered back and forth across the trailing edges of the compression regions by large-amplitude Alfvacute en waves. Our results also show that the proton intensity was well correlated with the compression ratio during low solar activity periods but was essentially independent of C during periods of high solar activity. We suggest that the correlation between J and C was not observed during solar active periods because of significant variations in the seed intensity that result from sporadic contributions from transient solar events. In contrast, the correlation was observable during quiescent periods probably because contributions from transients had decreased dramatically, which allowed the CIRs to accelerate particles out of a seed population whose intensity remained relatively unperturbed. copyright 1998 American Geophysical Union

  8. THE ROLL-OVER OF HELIOSPHERIC NEUTRAL HYDROGEN BELOW 100 eV: OBSERVATIONS AND IMPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Galli, A.; Wurz, P. [Physics Institute, University of Bern, Bern, 3012 (Switzerland); Schwadron, N. A.; Kucharek, H.; Möbius, E. [University of New Hampshire, Durham, NH 03824 (United States); Bzowski, M.; Sokół, J. M.; Kubiak, M. A. [Space Research Centre, Polish Academy of Sciences, Warsaw, 00-716 (Poland); Funsten, H. O. [Los Alamos National Laboratory, Intelligence and Space Research Division, Los Alamos, NM 87545 (United States); Fuselier, S. A.; McComas, D. J. [Southwest Research Institute, San Antonio, TX 78228 (United States)

    2016-04-20

    We present an improved analysis of the energy spectrum of energetic neutral hydrogen from the heliosheath observed with the IBEX -Lo sensor on the Interstellar Boundary EXplorer from the years 2009 to 2012. This analysis allows us to study the lowest energies between 10 and 100 eV although various background sources are more intense than the targeted signal over broad areas of the sky. The results improve our knowledge of the interaction region between our heliosphere and the interstellar plasma because these neutral atoms are direct messengers from the low-energy plasma in the heliosheath. We find a roll-over of the energy spectrum below 100 eV, which has major implications for the pressure balance of the plasma in the inner heliosheath. The results can also be compared directly with in situ observations of the Voyager 1 and 2 spacecraft.

  9. Overview of the HELCATS project

    Science.gov (United States)

    Harrison, Richard; Davies, Jackie; Perry, Chris; Moestl, Christian; Rouillard, Alexis; Bothmer, Volker; Rodriguez, Luciano; Eastwood, Jonathan; Kilpua, Emilia; Gallagher, Peter; Odstrcil, Dusan

    2017-04-01

    Understanding solar wind evolution is fundamental to advancing our knowledge of energy and mass transport in the solar system, whilst also being crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of solar wind evolution, by enabling direct and continuous observation of both transient and background components of the solar wind as they propagate from the Sun to 1 AU and beyond. The EU-funded FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project combines European expertise in heliospheric imaging, built up over the last decade in particular through lead involvement in NASA's STEREO mission, with expertise in solar and coronal imaging as well as the interpretation of in-situ and radio diagnostic measurements of solar wind phenomena. HELCATS involves: (1) cataloguing of transient (coronal mass ejections) and background (stream/corotating interaction regions) solar wind structures observed by the STEREO/Heliospheric Imagers, including estimates of their kinematic properties based on a variety of modelling techniques; (2) verifying these kinematic properties through comparison with solar source observations and in-situ measurements at multiple points throughout the heliosphere; (3) assessing the potential for initialising numerical models based on the derived kinematic properties of transient and background solar wind components; (4) assessing the complementarity of radio observations (Type II radio bursts and interplanetary scintillation) in the detection and analysis of heliospheric structure in combination with heliospheric imaging observations. We provide an overview of the achievements of the HELCATS project, as it reaches its conclusion, and present selected results that seek to illustrate the value and legacy of this unprecedented, coordinated study of structures in the heliosphere.

  10. Flow downstream of the heliospheric terminal shock: Magnetic field line topology and solar cycle imprint

    Science.gov (United States)

    Nerney, Steven; Suess, S. T.; Schmahl, E. J.

    1995-01-01

    The topology of the magnetic field in the heliosheath is illustrated using plots of the field lines. It is shown that the Archimedean spiral inside the terminal shock is rotated back in the heliosheath into nested spirals that are advected in the direction of the interstellar wind. The 22-year solar magnetic cycle is imprinted onto these field lines in the form of unipolar magnetic envelopes surrounded by volumes of strongly mixed polarity. Each envelope is defined by the changing tilt of the heliospheric current sheet, which is in turn defined by the boundary of unipolar high-latitude regions on the Sun that shrink to the pole at solar maximum and expand to the equator at solar minimum. The detailed shape of the envelopes is regulated by the solar wind velocity structure in the heliosheath.

  11. Neutralized solar energetic particles in the inner heliosphere: a parameter study

    Science.gov (United States)

    Wang, Xiao-Dong; Klecker, Berndt; Futaana, Yoshifumi; Cipriani, Fabrice; Barabash, Stas; Wieser, Martin

    2016-04-01

    The large fluxes of solar energetic particles (SEPs) in Gradual Events, dominated by protons, are believed to be produced by the acceleration of shocks driven by coronal mass ejections (CMEs). As SEPs propagate in the lower corona, there is a chance for them to be neutralized via the charge exchange and/or recombination processes and become energetic neutral atoms (ENAs). These ENAs retain the velocity of their parent SEPs and propagate in straight lines without the influence of the interplanetary magnetic field, and therefore might potentially serve as a new window to observe the particle acceleration processes in the solar corona. STEREO/Low Energy Telescope reported the first probable observation of hydrogen ENAs between 1.6 MeV - 5 MeV from the Sun prior to an X-class flare/CME [Mewaldt et al., 2009]. While such observations were somehow controversial, Wang et al. [2014] simulated the neutralization of solar energetic protons in the corona lower than 40 RS, and the result agreed with the STEREO observation. In this work, we further developed a production model of the ENA near the sun together with a transport model toward the inner planets, and explore the dependences of the ENA characteristics against the model parameters. These parameters include the angular width of the CME, its propagation direction with respect to the Sun-observer line, the propagation speed, the particle density in the corona, the abundances of O6+ and C4+, and the reaction rate of electron impact ionization in the loss of ENAs, and the heliospheric distance of the observer. The calculated ENA flux shows that at lower energy the expected ENA flux depends most sensitively on the CME apex angle and the CME propagation direction. At higher energy the dependence on the coronal density is more prominent. References Mewaldt, R. A., R. A. Leske, E. C. Stone, A. F. Barghouty, A. W. Labrador, C. M. S. Cohen, A. C. Cummings, A. J. Davis, T. T. von Rosenvinge, and M. E. Wiedenbeck (2009), STEREO

  12. Plasma surrounding the global heliosphere at large distances controlled by the solar cycle

    Science.gov (United States)

    Dialynas, Konstantinos; Krimigis, Stamatios; Mitchell, Donald; Decker, Robert; Roelof, Edmond

    2016-04-01

    The past decade can be characterized by a series of key, groundbreaking remote energetic neutral atom (ENA) images (INCA, IBEX) and in-situ ion (Voyager 1 & 2) observations concerning the characteristics and interactions of the heliosphere with the Local Interstellar Medium (LISM). Voyagers 1 and 2 (V1, V2) discovered the reservoir of ions and electrons that constitute the heliosheath (HS) after crossing the termination shock (TS) 35deg north and 32deg south of the ecliptic plane at 94 and 84 astronomical units (1 AU= 1.5 x108 km), respectively. The in situ measurements by each Voyager were placed in a global context by remote sensing images using ENA obtained with the Ion and Neutral Camera (INCA) onboard Cassini orbiting Saturn. The ENA images contain a 5.2-55 keV hydrogen (H) ENA region (Belt) that loops through the celestial sphere and contributes to balancing the pressure of the interstellar magnetic field (ISMF). The success of any future mission with dedicated ENA detectors (e.g. the IMAP mission), highly depends on the antecedent understanding of the details of the plasma processes in the Heliosphere as revealed by remote sensing of the plasma environment characteristics. Therefore, we address here one of the remaining and most important questions: "Where do the 5-55 keV ENAs that INCA measures come from?". We analyzed INCA all-sky maps from 2003 to 2015 and compare the solar cycle (SC) variation of the ENAs in both the nose (upstream) and anti-nose (downstream) directions with the intensities of > 30 keV ions (source of ENA through charge exchange-CE with H) measured in-situ by V1 and V2, in overlapping energy bands ~30-55 keV. ENA intensities decrease during the declining phase of SC23 by ~x3 from 2003 to 2011 but recover through 2014 (SC24); similarly, V1 and V2 ion intensities also decrease and then recover through 2014. The similarity of time profiles of remotely sensed ENA and locally measured ions are consistent with (a) ENA originating in the HS

  13. Characterization of the radiation environment of the inner heliosphere using LRO/CRaTER and EMMREM

    Science.gov (United States)

    Joyce, Colin J.

    2016-08-01

    I provide a characterization of the radiation environment of the inner heliosphere from mid-2009 to present using measurements made by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) aboard the Lunar Reconnaissance Orbiter (LRO) and modelling provided by the Earth-Moon-Mars Radiation Environment Module (EMMREM). In the course of this study, I analyze solar energetic particle (SEP) radiation in the form of four major solar events that occurred during this time range as well as the evolution of galactic cosmic ray (GCR) modulation over a period in which relatively calm solar conditions have resulted in the highest GCR fluxes measured in the space age. Using CRaTER measurements taken during three major solar events that occurred in 2012, I demonstrate a validation of the online PREDICCS system (Predictions of radiation from REleASE, EMMREM, and Data Incorporating CRaTER, COSTEP, and other SEP measurements), which uses EMMREM to provide near real-time radiation modelling at the Earth, Moon and Mars, finding PREDICCS to be quite accurate in modelling the peak dose rates and total accumulated doses for major solar events. Having demonstrated the accuracy of PREDICCS/EMMREM in modelling SEP events, EMMREM is used to provide an analysis of the potential radiation hazard of the extreme solar event observed by STEREO A on 23 July 2012, an event which has drawn comparisons to the historic Carrington event due to the exceptional size and record speed of the interplanetary coronal mass ejection associated with it. Such an event might be viewed as something like a worst case scenario in terms of the threat of SEP radiation to astronauts, however the evidence shown here suggests that, with the benefit of heavy protective shielding, astronauts would not have been exposed to levels of radiation that approach NASA's permissible exposure limits. These findings add to a mounting set of evidence which suggests that, contrary to conventional wisdom, the largest radiation

  14. Long-term solar activity and its implications to the heliosphere, geomagnetic activity, and the Earth’s climate

    Directory of Open Access Journals (Sweden)

    Tanskanen Eija

    2013-06-01

    Full Text Available The Sun’s long-term magnetic variability is the primary driver of space climate. This variability is manifested not only in the long-observed and dramatic change of magnetic fields on the solar surface, but also in the changing solar radiative output across all wavelengths. The Sun’s magnetic variability also modulates the particulate and magnetic fluxes in the heliosphere, which determine the interplanetary conditions and impose significant electromagnetic forces and effects upon planetary atmospheres. All these effects due to the changing solar magnetic fields are also relevant for planetary climates, including the climate of the Earth. The ultimate cause of solar variability, at time scales much shorter than stellar evolutionary time scales, i.e., at decadal to centennial and, maybe, even millennial or longer scales, has its origin in the solar dynamo mechanism. Therefore, in order to better understand the origin of space climate, one must analyze different proxies of solar magnetic variability and develop models of the solar dynamo mechanism that correctly produce the observed properties of the magnetic fields. This Preface summarizes the most important findings of the papers of this Special Issue, most of which were presented in the Space Climate-4 Symposium organized in 2011 in Goa, India.

  15. Models Archive and ModelWeb at NSSDC

    Science.gov (United States)

    Bilitza, D.; Papitashvili, N.; King, J. H.

    2002-05-01

    In addition to its large data holdings, NASA's National Space Science Data Center (NSSDC) also maintains an archive of space physics models for public use (ftp://nssdcftp.gsfc.nasa.gov/models/). The more than 60 model entries cover a wide range of parameters from the atmosphere, to the ionosphere, to the magnetosphere, to the heliosphere. The models are primarily empirical models developed by the respective model authors based on long data records from ground and space experiments. An online model catalog (http://nssdc.gsfc.nasa.gov/space/model/) provides information about these and other models and links to the model software if available. We will briefly review the existing model holdings and highlight some of its usages and users. In response to a growing need by the user community, NSSDC began to develop web-interfaces for the most frequently requested models. These interfaces enable users to compute and plot model parameters online for the specific conditions that they are interested in. Currently included in the Modelweb system (http://nssdc.gsfc.nasa.gov/space/model/) are the following models: the International Reference Ionosphere (IRI) model, the Mass Spectrometer Incoherent Scatter (MSIS) E90 model, the International Geomagnetic Reference Field (IGRF) and the AP/AE-8 models for the radiation belt electrons and protons. User accesses to both systems have been steadily increasing over the last years with occasional spikes prior to large scientific meetings. The current monthly rate is between 5,000 to 10,000 accesses for either system; in February 2002 13,872 accesses were recorded to the Modelsweb and 7092 accesses to the models archive.

  16. An Iterative Interplanetary Scintillation (IPS) Analysis Using Time-dependent 3-D MHD Models as Kernels

    Science.gov (United States)

    Jackson, B. V.; Yu, H. S.; Hick, P. P.; Buffington, A.; Odstrcil, D.; Kim, T. K.; Pogorelov, N. V.; Tokumaru, M.; Bisi, M. M.; Kim, J.; Yun, J.

    2017-12-01

    The University of California, San Diego has developed an iterative remote-sensing time-dependent three-dimensional (3-D) reconstruction technique which provides volumetric maps of density, velocity, and magnetic field. We have applied this technique in near real time for over 15 years with a kinematic model approximation to fit data from ground-based interplanetary scintillation (IPS) observations. Our modeling concept extends volumetric data from an inner boundary placed above the Alfvén surface out to the inner heliosphere. We now use this technique to drive 3-D MHD models at their inner boundary and generate output 3-D data files that are fit to remotely-sensed observations (in this case IPS observations), and iterated. These analyses are also iteratively fit to in-situ spacecraft measurements near Earth. To facilitate this process, we have developed a traceback from input 3-D MHD volumes to yield an updated boundary in density, temperature, and velocity, which also includes magnetic-field components. Here we will show examples of this analysis using the ENLIL 3D-MHD and the University of Alabama Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS) heliospheric codes. These examples help refine poorly-known 3-D MHD variables (i.e., density, temperature), and parameters (gamma) by fitting heliospheric remotely-sensed data between the region near the solar surface and in-situ measurements near Earth.

  17. JHelioviewer. Time-dependent 3D visualisation of solar and heliospheric data

    Science.gov (United States)

    Müller, D.; Nicula, B.; Felix, S.; Verstringe, F.; Bourgoignie, B.; Csillaghy, A.; Berghmans, D.; Jiggens, P.; García-Ortiz, J. P.; Ireland, J.; Zahniy, S.; Fleck, B.

    2017-09-01

    Context. Solar observatories are providing the world-wide community with a wealth of data, covering wide time ranges (e.g. Solar and Heliospheric Observatory, SOHO), multiple viewpoints (Solar TErrestrial RElations Observatory, STEREO), and returning large amounts of data (Solar Dynamics Observatory, SDO). In particular, the large volume of SDO data presents challenges; the data are available only from a few repositories, and full-disk, full-cadence data for reasonable durations of scientific interest are difficult to download, due to their size and the download rates available to most users. From a scientist's perspective this poses three problems: accessing, browsing, and finding interesting data as efficiently as possible. Aims: To address these challenges, we have developed JHelioviewer, a visualisation tool for solar data based on the JPEG 2000 compression standard and part of the open source ESA/NASA Helioviewer Project. Since the first release of JHelioviewer in 2009, the scientific functionality of the software has been extended significantly, and the objective of this paper is to highlight these improvements. Methods: The JPEG 2000 standard offers useful new features that facilitate the dissemination and analysis of high-resolution image data and offers a solution to the challenge of efficiently browsing petabyte-scale image archives. The JHelioviewer software is open source, platform independent, and extendable via a plug-in architecture. Results: With JHelioviewer, users can visualise the Sun for any time period between September 1991 and today; they can perform basic image processing in real time, track features on the Sun, and interactively overlay magnetic field extrapolations. The software integrates solar event data and a timeline display. Once an interesting event has been identified, science quality data can be accessed for in-depth analysis. As a first step towards supporting science planning of the upcoming Solar Orbiter mission, JHelioviewer

  18. The Fisk and Gloeckler model for the nose region of the heliosheath: Another model for Ed Stone to test

    International Nuclear Information System (INIS)

    Fisk, L A; Gloeckler, G

    2016-01-01

    Ed Stone has always been receptive to new ideas, including controversial ones, provided that the idea can be tested by observations. This paper will discuss the latest controversial idea for Ed to test: the Fisk and Gloeckler model for the nose region of the heliosheath, which concludes that Voyager 1 remains in the heliosphere and is not in the local interstellar medium, and that the nose region of the heliosheath is a very different place from what others have considered, and it can be argued, a more interesting place than others have imagined. The test of the model is that within this year, Voyager 1 should encounter another current sheet, due to the reversal of the magnetic field of the Sun, thereby establishing conclusively that Voyager 1 remains in the heliosphere. If/when the current sheet is crossed, it will be appropriate to extend the Fisk and Gloeckler model. A preview will be provided of these extensions and the interesting properties and physical properties that result for: (1) the region inside the Heliocliff ; (2) the Heliocliff ; (3) the region between the Heliocliff and the actual Heliopause ; and (4) the Heliopause . (paper)

  19. Spectral evolution of energetic neutral atom emissions at the heliospheric poles as measured by IBEX during its first three years

    Energy Technology Data Exchange (ETDEWEB)

    Dayeh, M. A.; Allegrini, F.; Desai, M. I.; Ebert, R. W.; Fuselier, S. A.; Livadiotis, G.; McComas, D. J.; Schwadron, N. A. [Southwest Research Institute, San Antonio, TX 78228 (United States); DeMajistre, R. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Janzen, P.; Reisenfeld, D. [University of Montana, Missoula, MT 59812 (United States); Siewert, M., E-mail: maldayeh@swri.edu [Institut für Astronomie der Universität Bonn, Abteilung f. Astrophysik und Extraterrestrische Forschung, Auf dem Hügel 71, D-53121 Bonn (Germany)

    2014-12-10

    The Interstellar Boundary Explorer (IBEX) mission continues to measure energetic neutral atom (ENA) emissions produced by charge exchange between solar wind (SW) protons and interstellar neutrals at the edge of our heliosphere. Using the first 3 yr of IBEX-Hi ENA measurements (2009-2011), we examined the spectral evolution of ∼0.5-6 keV ENAs at the polar regions (above 60°). We found the following: (1) pixels with a characteristic 'ankle' spectra (lower spectral index at higher energies) increase by ∼5% in 2010 and ∼10% in 2011 compared to 2009. (2) The averaged spectral index in 2011 is smaller than that of 2009. (3) The slope of the ENA spectrum above ∼1.7 keV is more variable than the slope below ∼1.7 keV. The lower spectral index at higher energies of the spectrum does not appear to be caused by an increase of the ENA production at these energies, but rather from a consistent decrease at lower energies. (4) The decrease in polar ENA fluxes does not correlate significantly with the averaged SW dynamic pressure, back-traced in time to 1 AU along the flow streamlines (originating between 10° and 30° for slow SW, and 60° and 80° for fast SW), assuming these are the respective conditions of ENA progenitors back in time. These results provide insights into the complexity of relating the slow and fast SW contributions to polar ENAs and shed light on how the solar output and the resulting change in the global heliospheric structure possibly affect the heliosheath (HS) populations.

  20. Solar and Heliospheric Observatory (SOHO) Flight Dynamics Simulations Using MATLAB (R)

    Science.gov (United States)

    Headrick, R. D.; Rowe, J. N.

    1996-01-01

    This paper describes a study to verify onboard attitude control laws in the coarse Sun-pointing (CSP) mode by simulation and to develop procedures for operational support for the Solar and Heliospheric Observatory (SOHO) mission. SOHO was launched on December 2, 1995, and the predictions of the simulation were verified with the flight data. This study used a commercial off the shelf product MATLAB(tm) to do the following: Develop procedures for computing the parasitic torques for orbital maneuvers; Simulate onboard attitude control of roll, pitch, and yaw during orbital maneuvers; Develop procedures for predicting firing time for both on- and off-modulated thrusters during orbital maneuvers; Investigate the use of feed forward or pre-bias torques to reduce the attitude handoff during orbit maneuvers - in particular, determine how to use the flight data to improve the feed forward torque estimates for use on future maneuvers. The study verified the stability of the attitude control during orbital maneuvers and the proposed use of feed forward torques to compensate for the attitude handoff. Comparison of the simulations with flight data showed: Parasitic torques provided a good estimate of the on- and off-modulation for attitude control; The feed forward torque compensation scheme worked well to reduce attitude handoff during the orbital maneuvers. The work has been extended to prototype calibration of thrusters from observed firing time and observed reaction wheel speed changes.

  1. Cluster and SOHO - a joint endeavor by ESA and NASA to address problems in solar, heliospheric, and space plasma physics

    International Nuclear Information System (INIS)

    Schmidt, R.; Domingo, V.; Shawhan, S.D.; Bohlin, D.

    1988-01-01

    The NASA/ESA Solar-Terrestrial Science Program, which consists of the four-spacecraft cluster mission and the Solar and Heliospheric Observatory (SOHO), is examined. It is expected that the SOHO spacecraft will be launched in 1995 to study solar interior structure and the physical processes associated with the solar corona. The SOHO design, operation, data, and ground segment are discussed. The Cluster mission is designed to study small-scale structures in the earth's plasma environment. The Soviet Union is expected to contribute two additional spacecraft, which will be similar to Cluster in instrumentation and design. The capabilities, mission strategy, spacecraft design, payload, and ground segment of Cluster are discussed. 19 references

  2. Low-energy solar electrons and ions observed at Ulysses February-April, 1991 - The inner heliosphere as a particle reservoir

    Science.gov (United States)

    Roelof, E. C.; Gold, R. E.; Simnett, G. M.; Tappin, S. J.; Armstrong, T. P.; Lanzerotti, L. J.

    1992-01-01

    Ulysses observations at 2.5 AU of 38-315 keV electrons and 61-4752 keV ions during February-April 1991 suggest in several ways that, during periods of sustained high solar activity, the inner heliosphere serves as a 'reservoir' for low-energy solar particles. Particle increases were not associated one-to-one with large X-ray flares because of their poor magnetic connection, yet intensities in March-April remained well above their February levels. The rise phase of the particle event associated with the great flare of 2245UT March 22 lasted most of two days, while throughout the one-week decay phase, the lowest-energy ion fluxes were nearly equal at Ulysses and earth (IMP-8).

  3. Solar Sentinels: Report of the Science and Technology Definition Team

    Science.gov (United States)

    2006-01-01

    The goal of NASA s Living With a Star (LWS) program is to develop the scientific understanding necessary to effectively address those aspects of the connected Sun Earth system that directly affect life and society. Along with the other elements of LWS, Solar Sentinels aims to discover, understand, and model the heliospheric initiation, propagation, and solar connection of those energetic phenomena that adversely affect space exploration and life and society here on Earth. The Solar Sentinels mission will address the following questions: (1) How, where, and under what circumstances are solar energetic particles (SEPs) accelerated to high energies and how do they propagate through the heliosphere? And (2) How are solar wind structures associated with these SEPs, like CMEs, shocks, and high-speed streams, initiated, propagate, evolve, and interact in the inner heliosphere? The Sentinels STDT recommends implementing this mission in two portions, one optimized for inner heliospheric in-situ measurements and the other for solar remote observations. Sentinels will greatly enhance the overall LWS science return.

  4. Modeling the Global Coronal Field with Simulated Synoptic Magnetograms from Earth and the Lagrange Points L3, L4, and L5

    Science.gov (United States)

    Petrie, Gordon; Pevtsov, Alexei; Schwarz, Andrew; DeRosa, Marc

    2018-06-01

    The solar photospheric magnetic flux distribution is key to structuring the global solar corona and heliosphere. Regular full-disk photospheric magnetogram data are therefore essential to our ability to model and forecast heliospheric phenomena such as space weather. However, our spatio-temporal coverage of the photospheric field is currently limited by our single vantage point at/near Earth. In particular, the polar fields play a leading role in structuring the large-scale corona and heliosphere, but each pole is unobservable for {>} 6 months per year. Here we model the possible effect of full-disk magnetogram data from the Lagrange points L4 and L5, each extending longitude coverage by 60°. Adding data also from the more distant point L3 extends the longitudinal coverage much further. The additional vantage points also improve the visibility of the globally influential polar fields. Using a flux-transport model for the solar photospheric field, we model full-disk observations from Earth/L1, L3, L4, and L5 over a solar cycle, construct synoptic maps using a novel weighting scheme adapted for merging magnetogram data from multiple viewpoints, and compute potential-field models for the global coronal field. Each additional viewpoint brings the maps and models into closer agreement with the reference field from the flux-transport simulation, with particular improvement at polar latitudes, the main source of the fast solar wind.

  5. The solar modulation of galactic comic rays as described by a time-dependent drift model

    International Nuclear Information System (INIS)

    Le Roux, J.A.

    1990-09-01

    The modulation process is understood to be an interaction between cosmic rays and the solar wind. The heliosphere and the observed modulation of cosmic rays in the heliosphere was reviewed and the time-dependence nature of the long-term modulation of cosmic rays highligted. A two-dimensional time-dependent drift model that describes the long-term modulation of cosmic-rays is presented. Application of the time-dependent drift model during times of increased solar activity showed that drift should be reduced during such periods. Isolated Forbush decreases were also studied in an effort to explain some observed trends in the properties of the Forbush decrease as a function of radial distance. The magnitude of the Forbush decrease and its recovery time were therefore studied as a function of radial distance in the equatorial plane. 154 refs., 95 figs., 1 tab

  6. Suprathermal ions in the solar wind from the Voyager spacecraft: Instrument modeling and background analysis

    International Nuclear Information System (INIS)

    Randol, B M; Christian, E R

    2015-01-01

    Using publicly available data from the Voyager Low Energy Charged Particle (LECP) instruments, we investigate the form of the solar wind ion suprathermal tail in the outer heliosphere inside the termination shock. This tail has a commonly observed form in the inner heliosphere, that is, a power law with a particular spectral index. The Voyager spacecraft have taken data beyond 100 AU, farther than any other spacecraft. However, during extended periods of time, the data appears to be mostly background. We have developed a technique to self-consistently estimate the background seen by LECP due to cosmic rays using data from the Voyager cosmic ray instruments and a simple, semi-analytical model of the LECP instruments

  7. Probing the Boundaries of the Heliosphere Using Observations of the Polar ENA Flux from IBEX and Cassini/INCA

    Science.gov (United States)

    Reisenfeld, D. B.; Janzen, P. H.; Bzowski, M.; Dialynas, K.; Funsten, H. O.; Fuselier, S. A.; Galli, A.; Kubiak, M. A.; McComas, D. J.; Schwadron, N.; Sokol, J. M.

    2016-12-01

    The IBEX Mission has been collecting ENAs from the outer heliosphere for nearly eight years, or three-quarters of a solar cycle. In that time, we have observed clear evidence of the imprint of the solar cycle in the time variation in the ENA flux. The most detailed of such studies has focused on the polar ENA flux observed by IBEX-Hi, as the IBEX spacecraft attitude allows for continuous coverage of the ENA flux incident from the ecliptic poles (Reisenfeld et al. 2012, 2016). By time correlating the ENA-derived heliosheath pressure to the observed 1 AU dynamic pressure, we can estimate the distance to the ENA source region. We can further derive the thickness of the ENA-producing region (presumably the inner heliosheath) by assuming pressure balance at the termination shock (TS). This requires using the 1 AU observations to derive the dynamic pressure at the TS shock by use of a mass-loaded solar wind propagation model (Schwadron et al. 2011), and by integrating ENA observations across all energies that significantly contribute to the heliosheath pressure. This means including polar ENA observations from not only IBEX-Hi, but from IBEX-Lo and Cassini/INCA, spanning an energy range of 15 eV to 40 keV. We will present our latest polar ENA observations and estimates for the distance to the TS and the thickness of the heliosheath.

  8. Interstellar Neutral Helium in the Heliosphere from IBEX Observations. V. Observations in IBEX-Lo ESA Steps 1, 2, and 3

    Science.gov (United States)

    Swaczyna, Paweł; Bzowski, Maciej; Kubiak, Marzena A.; Sokół, Justyna M.; Fuselier, Stephen A.; Galli, André; Heirtzler, David; Kucharek, Harald; McComas, David J.; Möbius, Eberhard; Schwadron, Nathan A.; Wurz, P.

    2018-02-01

    Direct-sampling observations of interstellar neutral (ISN) He by the Interstellar Boundary Explorer (IBEX) provide valuable insight into the physical state of and processes operating in the interstellar medium ahead of the heliosphere. The ISN He atom signals are observed at the four lowest ESA steps of the IBEX-Lo sensor. The observed signal is a mixture of the primary and secondary components of ISN He and H. Previously, only data from one of the ESA steps have been used. Here, we extend the analysis to data collected in the three lowest ESA steps with the strongest ISN He signal, for the observation seasons 2009–2015. The instrument sensitivity is modeled as a linear function of the atom impact speed onto the sensor’s conversion surface separately for each ESA step of the instrument. We find that the sensitivity increases from lower to higher ESA steps, but within each of the ESA steps it is a decreasing function of the atom impact speed. This result may be influenced by the hydrogen contribution, which was not included in the adopted model, but seems to exist in the signal. We conclude that the currently accepted temperature of ISN He and velocity of the Sun through the interstellar medium do not need a revision, and we sketch a plan of further data analysis aiming at investigating ISN H and a better understanding of the population of ISN He originating in the outer heliosheath.

  9. Solar Heliospheric and INterplanetary Environment (SHINE) Students - Student Representatives' Perspectives

    Science.gov (United States)

    Pahud, D. M.; Niembro, T.

    2014-12-01

    The SHINE workshop is an annual meeting of solar and heliospheric scientists which, in addition to aiming to improve understanding of solar disturbances and their propagation to, and effect, on the Earth (shinecon.org), is dedicated to actively supporting students. This dedication is substantiated in part through the National Science Foundation (NSF) providing funding for student attendance to the workshop, which enables student participation. Another example of SHINE's commitment to its student members is the incorporation of a Student Day prior to the workshop since 2003, entirely organized and run by two student representatives. While there are variations in format from year to year, Student Day consists of tutorials and research talks exclusively by student volunteers to an audience of only students. The day is intended to provide a low-stress environment for students to learn about the various topics addressed during the workshop, to ask questions freely, and to engage in scientific discussion with other students which hopefully is a catalyst for collaboration. As a result of positive experiences, over the past decade student attendance and participation in the workshop have increased. At the SHINE 2014 workshop, nearly a third of attendees were students. SHINE student visibility has increased over the years, with student posters being advertised at breakfast, inclusion of a student day summary by the student representatives during a plenary session, and continued support from the steering committee. Students are also promoting a broader impact of SHINE sciences via increased social media presence. From a student representative's perspective, SHINE has built and fostered a healthy student community and encourages students to engage in shaping the future of the field.

  10. Interplanetary Magnetic Field Power Spectrum Variations in the Inner Heliosphere: A Wind and MESSENGER Study

    Science.gov (United States)

    Szabo, Adam; Koval, A.

    2011-01-01

    The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the similar observations made by the MESSENGER spacecraft in the inner heliosphere affords an opportunity to compare magnetic field power spectral density variations as a function of radial distance from the Sun under different solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the approx.2 Hz limit above which digitization noise becomes apparent. The powe'r spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions. Wind and MESSENGER magnetic fluctuations are compared for times when the two spacecraft are close to radial and Parker field alignment. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed.

  11. Long-term Longitudinal Recurrences of the Open Magnetic Flux Density in the Heliosphere

    Energy Technology Data Exchange (ETDEWEB)

    Dósa, M.; Erdős, G., E-mail: dosa.melinda@wigner.mta.hu [Institute for Particle and Nuclear Physics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1121 Budapest, Konkoly-Thege Miklós st 29-33 (Hungary)

    2017-04-01

    Open magnetic flux in the heliosphere is determined from the radial component of the magnetic field vector measured onboard interplanetary space probes. Previous Ulysses research has shown remarkable independence of the flux density from heliographic latitude, explained by super-radial expansion of plasma. Here we are investigating whether any longitudinal variation exists in the 50 year long OMNI magnetic data set. The heliographic longitude of origin of the plasma package was determined by applying a correction according to the solar wind travel time. Significant recurrent enhancements of the magnetic flux density were observed throughout solar cycle 23, lasting for several years. Similar, long-lasting recurring features were observed in the solar wind velocity, temperature and the deviation angle of the solar wind velocity vector from the radial direction. Each of the recurrent features has a recurrence period slightly differing from the Carrington rotation rate, although they show a common trend in time. Examining the coronal temperature data of ACE leads to the possible explanation that these long-term structures are caused by slow–fast solar wind interaction regions. A comparison with MESSENGER data measured at 0.5 au shows that these longitudinal magnetic modulations do not exist closer to the Sun, but are the result of propagation.

  12. AN AB INITIO MODEL FOR COSMIC-RAY MODULATION

    Energy Technology Data Exchange (ETDEWEB)

    Engelbrecht, N. E.; Burger, R. A. [Center for Space Research, North-West University, Potchefstroom 2520 (South Africa)

    2013-07-20

    A proper understanding of the effects of turbulence on the diffusion and drift of cosmic rays (CRs) is of vital importance for a better understanding of CR modulation in the heliosphere. This study presents an ab initio model for CR modulation, incorporating for the first time the results yielded by a two-component turbulence transport model. This model is solved for solar minimum heliospheric conditions, utilizing boundary values chosen so that model results are in reasonable agreement with spacecraft observations of turbulence quantities in the solar ecliptic plane and along the out-of-ecliptic trajectory of the Ulysses spacecraft. These results are employed as inputs for modeled slab and two-dimensional (2D) turbulence energy spectra. The modeled 2D spectrum is chosen based on physical considerations, with a drop-off at the very lowest wavenumbers. There currently exist no models or observations for the wavenumber where this drop-off occurs, and it is considered to be the only free parameter in this study. The modeled spectra are used as inputs for parallel mean free path expressions based on those derived from quasi-linear theory and perpendicular mean free paths from extended nonlinear guiding center theory. Furthermore, the effects of turbulence on CR drifts are modeled in a self-consistent way, also employing a recently developed model for wavy current sheet drift. The resulting diffusion and drift coefficients are applied to the study of galactic CR protons and antiprotons using a 3D, steady-state CR modulation code, and sample solutions in fair to good agreement with multiple spacecraft observations are presented.

  13. Recent Successes of Wave/Turbulence Driven Models of Solar Wind Acceleration

    Science.gov (United States)

    Cranmer, S. R.; Hollweg, J. V.; Chandran, B. D.; van Ballegooijen, A. A.

    2010-12-01

    A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a first-principles understanding of coronal heating. Also, it is still unknown whether the solar wind is "fed" through flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy are input intermittently from closed loops into the open-field regions. In this presentation, we discuss self-consistent models that assume the energy comes from solar Alfven waves that are partially reflected, and then dissipated, by magnetohydrodynamic turbulence. These models have been found to reproduce many of the observed features of the fast and slow solar wind without the need for artificial "coronal heating functions" used by earlier models. For example, the models predict a variation with wind speed in commonly measured ratios of charge states and elemental abundances that agrees with observed trends. This contradicts a commonly held assertion that these ratios can only be produced by the injection of plasma from closed-field regions on the Sun. This presentation also reviews two recent comparisons between the models and empirical measurements: (1) The models successfully predict the amplitude and radial dependence of Faraday rotation fluctuations (FRFs) measured by the Helios probes for heliocentric distances between 2 and 15 solar radii. The FRFs are a particularly sensitive test of turbulence models because they depend not only on the plasma density and Alfven wave amplitude in the corona, but also on the turbulent correlation length. (2) The models predict the correct sense and magnitude of changes seen in the polar high-speed solar wind by Ulysses from the previous solar minimum (1996-1997) to the more recent peculiar minimum (2008-2009). By changing only the magnetic field along the polar magnetic flux tube, consistent with solar and heliospheric observations at the two epochs, the model correctly predicts that the

  14. Pickup Protons: Comparisons using the Three-Dimensional MHD HHMS-PI model and Ulysses SWICS Measurements

    Science.gov (United States)

    Intriligator, Devrie S.; Detman, Thomas; Gloecker, George; Gloeckler, Christine; Dryer, Murray; Sun, Wei; Intriligator, James; Deehr, Charles

    2012-01-01

    We report the first comparisons of pickup proton simulation results with in situ measurements of pickup protons obtained by the SWICS instrument on Ulysses. Simulations were run using the three dimensional (3D) time-dependent Hybrid Heliospheric Modeling System with Pickup Protons (HHMS-PI). HHMS-PI is an MHD solar wind model, expanded to include the basic physics of pickup protons from neutral hydrogen that drifts into the heliosphere from the local interstellar medium. We use the same model and input data developed by Detman et al. (2011) to now investigate the pickup protons. The simulated interval of 82 days in 2003 2004, includes both quiet solar wind (SW) and also the October November 2003 solar events (the Halloween 2003 solar storms). The HHMS-PI pickup proton simulations generally agree with the SWICS measurements and the HHMS-PI simulated solar wind generally agrees with SWOOPS (also on Ulysses) measurements. Many specific features in the observations are well represented by the model. We simulated twenty specific solar events associated with the Halloween 2003 storm. We give the specific values of the solar input parameters for the HHMS-PI simulations that provide the best combined agreement in the times of arrival of the solar-generated shocks at both ACE and Ulysses. We show graphical comparisons of simulated and observed parameters, and we give quantitative measures of the agreement of simulated with observed parameters. We suggest that some of the variations in the pickup proton density during the Halloween 2003 solar events may be attributed to depletion of the inflowing local interstellar medium (LISM) neutral hydrogen (H) caused by its increased conversion to pickup protons in the immediately preceding shock.

  15. Simulating multi-spacecraft Heliospheric Imager observations for tomographic reconstruction of interplanetary CMEs

    Science.gov (United States)

    Barnes, D.

    2017-12-01

    The multiple, spatially separated vantage points afforded by the STEREO and SOHO missions provide physicists with a means to infer the three-dimensional structure of the solar corona via tomographic imaging. The reconstruction process combines these multiple projections of the optically thin plasma to constrain its three-dimensional density structure and has been successfully applied to the low corona using the STEREO and SOHO coronagraphs. However, the technique is also possible at larger, inter-planetary distances using wide-angle imagers, such as the STEREO Heliospheric Imagers (HIs), to observe faint solar wind plasma and Coronal Mass Ejections (CMEs). Limited small-scale structure may be inferred from only three, or fewer, viewpoints and the work presented here is done so with the aim of establishing techniques for observing CMEs with upcoming and future HI-like technology. We use simulated solar wind densities to compute realistic white-light HI observations, with which we explore the requirements of such instruments for determining solar wind plasma density structure via tomography. We exploit this information to investigate the optimal orbital characteristics, such as spacecraft number, separation, inclination and eccentricity, necessary to perform the technique with HIs. Further to this we argue that tomography may be greatly enhanced by means of improved instrumentation; specifically, the use of wide-angle imagers capable of measuring polarised light. This work has obvious space weather applications, serving as a demonstration for potential future missions (such as at L1 and L5) and will prove timely in fully exploiting the science return from the upcoming Solar Orbiter and Parker Solar Probe missions.

  16. IHY Modeling Support at the Community Coordinated Modeling Center

    Science.gov (United States)

    Chulaki, A.; Hesse, Michael; Kuznetsova, Masha; MacNeice, P.; Rastaetter, L.

    2005-01-01

    The Community Coordinated Modeling Center (CCMC) is a US inter-agency activity aiming at research in support of the generation of advanced space weather models. As one of its main functions, the CCMC provides to researchers the use of space science models, even if they are not model owners themselves. In particular, the CCMC provides to the research community the execution of "runs-onrequest" for specific events of interest to space science researchers. Through this activity and the concurrent development of advanced visualization tools, CCMC provides, to the general science community, unprecedented access to a large number of state-of-the-art research models. CCMC houses models that cover the entire domain from the Sun to the Earth. In this presentation, we will provide an overview of CCMC modeling services that are available to support activities during the International Heliospheric Year. In order to tailor CCMC activities to IHY needs, we will also invite community input into our IHY planning activities.

  17. Low-Energy Neutron Production in Solar Flares and the Importance of their Detection in the Inner Heliosphere

    Science.gov (United States)

    Murphy, Ronald; Kozlovsky, B.; Share, G.

    2012-05-01

    Neutron detectors on spacecraft in the inner-heliosphere can observe the low-energy (computer code incorporating up-dated neutron-production cross sections of the accelerated proton and alpha-particle reactions with heavier elements at low ion energies (Mercury. We conclude that a full understanding of ion acceleration, transport, and interaction at the Sun requires observations of both neutrons and gamma rays. We find that a measurement of the 2.223 MeV neutron-capture line, even with a modest instrument at 1 AU, is as sensitive to the presence of low-energy interacting ions at the Sun as a 1-10 MeV neutron detector at 0.5 AU. However, as the distance from the Sun to the neutron detector decreases, the tremendous increase of the low-energy neutron flux will allow exploration of ion acceleration in weak flares not previously observable and may reveal ion acceleration at other sites not previously detected where low-energy neutron production could be the only high-energy signature of ion acceleration.

  18. STRUCTURE, PROPAGATION, AND EXPANSION OF A CME-DRIVEN SHOCK IN THE HELIOSPHERE: A REVISIT OF THE 2012 JULY 23 EXTREME STORM

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D.; Hu, Huidong; Zhu, Bei [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Luhmann, Janet G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Vourlidas, Angelos, E-mail: liuxying@spaceweather.ac.cn [The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20732 (United States)

    2017-01-10

    We examine the structure, propagation, and expansion of the shock associated with the 2012 July 23 extreme coronal mass ejection. Characteristics of the shock determined from multi-point imaging observations are compared to in situ measurements at different locations and a complex radio type II burst, which according to our definition has multiple branches that may not all be fundamental-harmonic related. The white-light shock signature can be modeled reasonably well by a spherical structure and was expanding backward even on the opposite side of the Sun. The expansion of the shock, which was roughly self-similar after the first ∼1.5 hr from launch, largely dominated over the translation of the shock center for the time period of interest. Our study also suggests a bow-shock morphology around the nose at later times due to the outward motion in combination with the expansion of the ejecta. The shock decayed and failed to reach Mercury in the backward direction and the Solar Terrestrial Relations Observatory B ( STEREO B ) and Venus in the lateral directions, as indicated by the imaging and in situ observations. The shock in the nose direction, however, may have persisted to the far outer heliosphere, with predicted impact on Dawn around 06:00 UT on July 25 and on Jupiter around 23:30 UT on July 27 by a magnetohydrodynamic model. The type II burst shows properties generally consistent with the spatial/temporal variations of the shock deduced from imaging and in situ observations. In particular, the low-frequency bands agree well with the in situ measurements of a very low density ahead of the shock at STEREO A .

  19. Modeling a Single SEP Event from Multiple Vantage Points Using the iPATH Model

    Science.gov (United States)

    Hu, Junxiang; Li, Gang; Fu, Shuai; Zank, Gary; Ao, Xianzhi

    2018-02-01

    Using the recently extended 2D improved Particle Acceleration and Transport in the Heliosphere (iPATH) model, we model an example gradual solar energetic particle event as observed at multiple locations. Protons and ions that are energized via the diffusive shock acceleration mechanism are followed at a 2D coronal mass ejection-driven shock where the shock geometry varies across the shock front. The subsequent transport of energetic particles, including cross-field diffusion, is modeled by a Monte Carlo code that is based on a stochastic differential equation method. Time intensity profiles and particle spectra at multiple locations and different radial distances, separated in longitudes, are presented. The results shown here are relevant to the upcoming Parker Solar Probe mission.

  20. Cosmic Ray Modulation and Radiation Dose of Aircrews During Possible Grand Minimum

    Science.gov (United States)

    Miyake, S.; Kataoka, R.; Sato, T.; Imada, S.; Miyahara, H.; Shiota, D.; Matsumoto, T.; Ueno, H.

    2017-12-01

    The Sun is exhibiting low solar activity levels since the descending phase of the last solar cycle, and it is likely to be continued as well as in the case of the past grand solar minima. The cosmic-ray modulation, which is the variation of the galactic cosmic ray (GCR) spectrum caused by the heliospheric environmental change, is basically anti-correlated with the solar activity. In the recent weak solar cycle, we thus expect that the flux of GCRs is getting higher than that in the previous solar cycles, leading to the increase in the radiation exposure in the space and atmosphere. In order to quantitatively evaluate the possible solar modulation of GCRs and resultant radiation exposure at flight altitude, we have developed the time-dependent and three-dimensional model of the cosmic-ray modulation. Our model can give the flux of GCRs anywhere in the heliosphere by assuming the variation of the solar wind speed, the strength of the heliospheric magnetic field (HMF), and its tilt angle. We solve the gradient-curvature drift motion of GCRs in the HMF, and therefore reproduce the 22-year variation of the cosmic-ray modulation. We also calculate the neutron monitor counting rate and the radiation dose of aircrews at flight altitude, by the air-shower simulation performed by PHITS (Particle and Heavy Ion Transport code System). In our previous study [1], we calculated the radiation dose at a flight altitude during the coming solar cycle by assuming the variation of the solar wind speed and the strength of the HMF expressed by sinusoidal curve, and obtained that an annual radiation dose of aircrews in 5 years around the next solar minimum will be up to 19% higher than that at the last cycle. In this study, we predict the new model of the heliospheric environmental change on the basis of a prediction model for the sunspot number. The quantitative predictions of the cosmic-ray modulation and the radiation dose at a flight altitude during possible Grand Minimum considering

  1. ENERGETIC PARTICLE OBSERVATIONS AND PROPAGATION IN THE THREE-DIMENSIONAL HELIOSPHERE DURING THE 2006 DECEMBER EVENTS

    International Nuclear Information System (INIS)

    Malandraki, O. E.; Marsden, R. G.; Tranquille, C.; Lario, D.; Heber, B.; Mewaldt, R. A.; Cohen, C. M. S.; Lanzerotti, L. J.; Forsyth, R. J.; Elliott, H. A.; Vogiatzis, I. I.; Geranios, A.

    2009-01-01

    We report observations of solar energetic particles obtained by the HI-SCALE and COSPIN/LET instruments onboard Ulysses during the period of isolated but intense solar activity in 2006 December, in the declining phase of the solar activity cycle. We present measurements of particle intensities and also discuss observations of particle anisotropies and composition in selected energy ranges. Active Region 10930 produced a series of major solar flares with the strongest one (X9.0) recorded on December 5 after it rotated into view on the solar east limb. Located over the South Pole of the Sun, at >72 0 S heliographic latitude and 2.8 AU radial distance, Ulysses provided unique measurements for assessing the nature of particle propagation to high latitudes under near-minimum solar activity conditions, in a relatively undisturbed heliosphere. The observations seem to exclude the possibility that magnetic field lines originating at low latitudes reached Ulysses, suggesting either that the energetic particles observed as large solar energetic particle (SEP) events over the South Pole of the Sun in 2006 December were released when propagating coronal waves reached high-latitude field lines connected to Ulysses, or underwent perpendicular diffusion. We also discuss comparisons with energetic particle data acquired by the STEREO and Advanced Composition Explorer in the ecliptic plane near 1 AU during this period.

  2. The Interstellar Mapping and Acceleration Probe - A Mission to Discover the Origin of Particle Acceleration and its Fundamental Connection to the Global Interstellar Interaction

    Science.gov (United States)

    Schwadron, N.

    2017-12-01

    Our piece of cosmic real-estate, the heliosphere, is the domain of all human existence - an astrophysical case-history of the successful evolution of life in a habitable system. The Interstellar Boundary Explorer (IBEX) was the first mission to explore the global heliosphere and in concert with Voyager 1 and Voyager 2 is discovering a fundamentally new and uncharted physical domain of the outer heliosphere. In parallel, Cassini/INCA maps the global heliosphere at energies ( 5-55 keV) above those measured by IBEX. The enigmatic IBEX ribbon and the INCA belt were unanticipated discoveries demonstrating that much of what we know or think we understand about the outer heliosphere needs to be revised. The global structure of the heliosphere is highly complex and influenced by competing factors ranging from the local interstellar magnetic field, suprathermal populations both within and beyond the heliopause, and the detailed flow properties of the LISM. Global heliospheric structure and microphysics in turn influences the acceleration of energetic particles and creates feedbacks that modify the interstellar interaction as a whole. The next quantum leap enabled by IMAP will open new windows on the frontier of Heliophysics and probe the acceleration of suprathermal and higher energy particles at a time when the space environment is rapidly evolving. IMAP ultimately connects the acceleration processes observed directly at 1 AU with unprecedented sensitivity and temporal resolution with the global structure of our heliosphere. The remarkable synergy between IMAP, Voyager 1 and Voyager 2 will remain for at least the next decade as Voyager 1 pushes further into the interstellar domain and Voyager 2 moves through the heliosheath. IMAP, like ACE before it, will be a keystone of the Heliophysics System Observatory by providing comprehensive energetic particle, pickup ion, suprathermal ion, neutral atom, solar wind, solar wind heavy ion, and magnetic field observations to diagnose

  3. Characterizing a Model of Coronal Heating and Solar Wind Acceleration Based on Wave Turbulence.

    Science.gov (United States)

    Downs, C.; Lionello, R.; Mikic, Z.; Linker, J.; Velli, M.

    2014-12-01

    Understanding the nature of coronal heating and solar wind acceleration is a key goal in solar and heliospheric research. While there have been many theoretical advances in both topics, including suggestions that they may be intimately related, the inherent scale coupling and complexity of these phenomena limits our ability to construct models that test them on a fundamental level for realistic solar conditions. At the same time, there is an ever increasing impetus to improve our spaceweather models, and incorporating treatments for these processes that capture their basic features while remaining tractable is an important goal. With this in mind, I will give an overview of our exploration of a wave-turbulence driven (WTD) model for coronal heating and solar wind acceleration based on low-frequency Alfvénic turbulence. Here we attempt to bridge the gap between theory and practical modeling by exploring this model in 1D HD and multi-dimensional MHD contexts. The key questions that we explore are: What properties must the model possess to be a viable model for coronal heating? What is the influence of the magnetic field topology (open, closed, rapidly expanding)? And can we simultaneously capture coronal heating and solar wind acceleration with such a quasi-steady formulation? Our initial results suggest that a WTD based formulation performs adequately for a variety of solar and heliospheric conditions, while significantly reducing the number of free parameters when compared to empirical heating and solar wind models. The challenges, applications, and future prospects of this type of approach will also be discussed.

  4. The Drag-based Ensemble Model (DBEM) for Coronal Mass Ejection Propagation

    Science.gov (United States)

    Dumbović, Mateja; Čalogović, Jaša; Vršnak, Bojan; Temmer, Manuela; Mays, M. Leila; Veronig, Astrid; Piantschitsch, Isabell

    2018-02-01

    The drag-based model for heliospheric propagation of coronal mass ejections (CMEs) is a widely used analytical model that can predict CME arrival time and speed at a given heliospheric location. It is based on the assumption that the propagation of CMEs in interplanetary space is solely under the influence of magnetohydrodynamical drag, where CME propagation is determined based on CME initial properties as well as the properties of the ambient solar wind. We present an upgraded version, the drag-based ensemble model (DBEM), that covers ensemble modeling to produce a distribution of possible ICME arrival times and speeds. Multiple runs using uncertainty ranges for the input values can be performed in almost real-time, within a few minutes. This allows us to define the most likely ICME arrival times and speeds, quantify prediction uncertainties, and determine forecast confidence. The performance of the DBEM is evaluated and compared to that of ensemble WSA-ENLIL+Cone model (ENLIL) using the same sample of events. It is found that the mean error is ME = ‑9.7 hr, mean absolute error MAE = 14.3 hr, and root mean square error RMSE = 16.7 hr, which is somewhat higher than, but comparable to ENLIL errors (ME = ‑6.1 hr, MAE = 12.8 hr and RMSE = 14.4 hr). Overall, DBEM and ENLIL show a similar performance. Furthermore, we find that in both models fast CMEs are predicted to arrive earlier than observed, most likely owing to the physical limitations of models, but possibly also related to an overestimation of the CME initial speed for fast CMEs.

  5. Visualizing the Heliosphere

    Science.gov (United States)

    Bridgman, William T.; Shirah, Greg W.; Mitchell, Horace G.

    2008-01-01

    Today, scientific data and models can combine with modern animation tools to produce compelling visualizations to inform and educate. The Scientific Visualization Studio at Goddard Space Flight Center merges these techniques from the very different worlds of entertainment and science to enable scientists and the general public to 'see the unseeable' in new ways.

  6. On the Statistical Properties of Turbulent Energy Transfer Rate in the Inner Heliosphere

    Science.gov (United States)

    Sorriso-Valvo, Luca; Carbone, Francesco; Perri, Silvia; Greco, Antonella; Marino, Raffaele; Bruno, Roberto

    2018-01-01

    The transfer of energy from large to small scales in solar wind turbulence is an important ingredient of the long-standing question of the mechanism of the interplanetary plasma heating. Previous studies have shown that magnetohydrodynamic (MHD) turbulence is statistically compatible with the observed solar wind heating as it expands in the heliosphere. However, in order to understand which processes contribute to the plasma heating, it is necessary to have a local description of the energy flux across scales. To this aim, it is customary to use indicators such as the magnetic field partial variance of increments (PVI), which is associated with the local, relative, scale-dependent magnetic energy. A more complete evaluation of the energy transfer should also include other terms, related to velocity and cross-helicity. This is achieved here by introducing a proxy for the local, scale-dependent turbulent energy transfer rate ɛ_{Δ t}(t), based on the third-order moment scaling law for MHD turbulence. Data from Helios 2 are used to determine the statistical properties of such a proxy in comparison with the magnetic and velocity fields PVI, and the correlation with local solar wind heating is computed. PVI and ɛ_{Δ t}(t) are generally well correlated; however, ɛ_{Δ t}(t) is a very sensitive proxy that can exhibit large amplitude values, both positive and negative, even for low amplitude peaks in the PVI. Furthermore, ɛ_{Δ t}(t) is very well correlated with local increases of the temperature when large amplitude bursts of energy transfer are localized, thus suggesting an important role played by this proxy in the study of plasma energy dissipation.

  7. UPDATED ANALYSIS OF THE UPWIND INTERPLANETARY HYDROGEN VELOCITY AS OBSERVED BY THE HUBBLE SPACE TELESCOPE DURING SOLAR CYCLE 23

    International Nuclear Information System (INIS)

    Vincent, Frederic E.; Ben-Jaffel, Lotfi; Harris, Walter M.

    2011-01-01

    The interplanetary hydrogen (IPH), a population of neutrals that fill the space between planets inside the heliosphere, carries the signature of the interstellar medium (ISM) and the heliospheric interface. As the incoming ISM-ionized component deflects at the heliopause, charge exchange reactions decelerate the bulk motion of the neutrals that penetrate the heliosphere. Inside the heliosphere, the IPH bulk velocity is further affected by solar gravity, radiation pressure, and ionization processes, with the latter two processes dependent on solar activity. Solar cycle 23 provided the first partial temporal map of the IPH velocity, including measurements from the Hubble Space Telescope (HST) spectrometers (Goddard High Resolution Spectrograph (GHRS) and Space Telescope Imaging Spectrograph (STIS)) and the Solar and Heliospheric Observatory/Solar Wind ANisotropies (SWAN) instrument. We present an updated analysis of IPH velocity measurements from GHRS and STIS and compare these results with those of SWAN and two different time-dependent models. Our reanalysis of STIS data reveals a significant change in IPH velocity relative to earlier reports, because of the contamination by geocoronal oxygen that was not accounted for. While current models of the heliospheric interface predict the observed IPH velocity for solar maximum, they are not consistent with data covering solar minimum. With updates to the HST data points, we now find that all data can be fit by the existing models to within 1σ, with the exception of SWAN observations taken at solar minimum (1997/1998). We conclude that the current data lack the temporal coverage and/or precision necessary to determine the detailed characteristics of the solar cycle dependence. Hence, new observations are merited.

  8. Neutron-decay Protons from Solar Flares as Seed Particles for CME-shock Acceleration in the Inner Heliosphere

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Ronald J. [Code 7650, Naval Research Laboratory, Washington, DC 20375 (United States); Ko, Yuan-Kuen, E-mail: ronald.murphy@nrl.navy.mil, E-mail: yuan-kuen.ko@nrl.navy.mil [Code 7680, Naval Research Laboratory, Washington, DC 20375 (United States)

    2017-09-01

    The protons in large solar energetic particle events are accelerated in the inner heliosphere by fast shocks produced by coronal mass ejections. Unless there are other sources, the protons these shocks act upon would be those of the solar wind (SW). The efficiency of the acceleration depends on the kinetic energy of the protons. For a 2000 km s{sup −1} shock, the most effective proton energies would be 30–100 keV; i.e., within the suprathermal tail component of the SW. We investigate one possible additional source of such protons: those resulting from the decay of solar-flare-produced neutrons that escape from the Sun into the low corona. The neutrons are produced by interactions of flare-accelerated ions with the solar atmosphere. We discuss the production of low-energy neutrons in flares and their decay on a interplanetary magnetic field line near the Sun. We find that even when the flaring conditions are optimal, the 30–100 keV neutron-decay proton density produced by even a very large solar flare would be only about 10% of that of the 30–100 keV SW suprathermal tail. We discuss the implication of a seed-particle source of more frequent, small flares.

  9. A Data-driven Model of the Solar Wind, Interstellar Pickup Ions, and Turbulence Throughout the Interplanetary Space

    Science.gov (United States)

    Kim, T. K.; Kryukov, I.; Pogorelov, N. V.; Elliott, H. A.; Zank, G. P.

    2017-12-01

    The outer heliosphere is an interesting region characterized by the interaction between the solar wind and the interstellar neutral atoms. Having accomplished the mission to Pluto in 2015 and currently on the way to the Kuiper Belt, the New Horizons spacecraft is following the footsteps of the two Voyager spacecraft that previously explored this region lying roughly beyond 30 AU from the Sun. We model the three-dimensional, time-dependent solar wind plasma flow to the outer heliosphere using our own software Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS), which, in addition to the thermal solar wind plasma, takes into account charge exchange of the solar wind protons with interstellar neutral atoms and treats nonthermal ions (i.e., pickup ions) born during this process as a separate fluid. Additionally, MS-FLUKSS allows us to model turbulence generated by pickup ions. We use MS-FLUKSS to investigate the evolution of plasma and turbulent fluctuations along the trajectory of the New Horizons spacecraft using plasma and turbulence parameters from OMNI data as time-dependent boundary conditions at 1 AU for the Reynolds-averaged MHD equations. We compare the model with in situ plasma observations by New Horizons, Voyager 2, and Ulysses. We also compare the model pickup proton parameters with those derived from the Ulysses-SWICS data.

  10. The Production of Low-energy Neutrons in Solar Flares and the Importance of Their Detection in the Inner Heliosphere

    Science.gov (United States)

    Murphy, R. J.; Kozlovsky, B.; Share, G. H.

    2012-09-01

    Neutron detectors on spacecraft in the inner heliosphere can observe the low-energy (computer code incorporating updated neutron-production cross sections for the proton and α-particle reactions with heavier elements at all ion energies, especially at low energies (E ion Mercury has such a detector. We conclude that a full understanding of ion acceleration, transport, and interaction at the Sun requires observation of both neutrons and gamma rays with detectors of comparable sensitivity. We find that the neutron-capture line fluence at 1 AU is comparable to the 1-10 MeV neutron fluence at 0.5 AU, and therefore as effective for revealing low-energy ion acceleration. However, as the distance from the Sun to the neutron detector decreases, the tremendous increase of the low-energy neutron flux allows exploration of ion acceleration in weak flares not previously observable and may reveal acceleration at other sites not previously detected where low-energy neutrons could be the only high-energy signature of ion acceleration. Also, a measurement of the low-energy neutron spectrum will provide important information about the accelerated-ion spectrum that is not available from the capture line fluence measurement alone.

  11. Two-dimensional numerical modeling of the cosmic ray storm

    International Nuclear Information System (INIS)

    Kadokura, A.; Nishida, A.

    1986-01-01

    A numerical model of the cosmic ray storm in the two-dimensional heliosphere is constructed incorporating the drift effect. We estimate the effect of a flare-associated interplanetary shock and the disturbed region behind it (characterized by enhancement in velocity and magnetic field, and decrease in mean free path) on the density and anisotropy of cosmic rays in the heliosphere. As the disturbance propagates outward, a density enhancement appears on the front side, and a density depression region is produced on the rear side. The effect of drift on the cosmic ray storm appears most clearly in the higher-latitude region. For the parallel (antiparallel) state of the solar magnetic field which corresponds to the pre(post-) 1980 period, the density in the higher-latitude region decreases (increases) before the shock arrival. The maximum density depression near the earth for the parallel state is greater than for the antiparallel state, and the energy spectrum of the density depression in percentage is softer for the parallel state than for the antiparallel state. Prior to the arrival of the shock, the phase of solar diurnal anisotropy begins to shift to the earlier hours, and its amplitude becomes greater for both polarity states. North-south anisotropy also becomes greater because of the enhanced drift for both polarity states

  12. SECONDARY POPULATION OF INTERSTELLAR NEUTRALS seems deflected to the side

    Science.gov (United States)

    Nakagawa, H.; Bzowski, M.; Yamazaki, A.; Fukunishi, H.; Watanabe, S.; Takahashi, Y.; Taguchi, M.

    Recently the neutral hydrogen flow in the inner heliosphere was found to be deflected relative to the helium flow by about 4 degrees Lallement et al 2005 The explanation of this delfection offered was a distortion of the heliosphere under the action of an ambient interstellar magnetic field In a separate study a number of data sets pertaining to interstellar neutral atoms obtained with various techniques were compiled and interpreted as due to an inflow of interstellar gas from an ecliptic longitude shifted by 10 - 40 degrees from the canonical upstream interstellar neutral flow direction at 254 degrees Collier et al 2004 The origin and properties of such a flow is still under debate We have performed a cross-experiment analysis of the heliospheric hydrogen and helium photometric observations performed simltaneously by the Nozomi spacecraft between the Earth and Mars orbit and explored possible deflection of hydrogen and helium flows with respect to the canonical upwind direction For the interpretation we used predictions of a state of the art 3D and fully time-dependent model of the neutral gas in the heliosphere with the boundary conditions ionization rates and radiation pressure taken from literature The model includes two populations of the thermal interstellar hydrogen predicted by the highly-reputed Moscow Monte Carlo model of the heliosphere The agreement between the data and simulations is not satifactory when one assumes that the upwind direction is the same for both populations and identical with the direction derived from inerstellar helium

  13. THE EFFECT OF A DYNAMIC INNER HELIOSHEATH THICKNESS ON COSMIC-RAY MODULATION

    International Nuclear Information System (INIS)

    Manuel, R.; Ferreira, S. E. S.; Potgieter, M. S.

    2015-01-01

    The time-dependent modulation of galactic cosmic rays in the heliosphere is studied over different polarity cycles by computing 2.5 GV proton intensities using a two-dimensional, time-dependent modulation model. By incorporating recent theoretical advances in the relevant transport parameters in the model, we showed in previous work that this approach gave realistic computed intensities over a solar cycle. New in this work is that a time dependence of the solar wind termination shock (TS) position is implemented in our model to study the effect of a dynamic inner heliosheath thickness (the region between the TS and heliopause) on the solar modulation of galactic cosmic rays. The study reveals that changes in the inner heliosheath thickness, arising from a time-dependent shock position, does affect cosmic-ray intensities everywhere in the heliosphere over a solar cycle, with the smallest effect in the innermost heliosphere. A time-dependent TS position causes a phase difference between the solar activity periods and the corresponding intensity periods. The maximum intensities in response to a solar minimum activity period are found to be dependent on the time-dependent TS profile. It is found that changing the width of the inner heliosheath with time over a solar cycle can shift the time of when the maximum or minimum cosmic-ray intensities occur at various distances throughout the heliosphere, but more significantly in the outer heliosphere. The time-dependent extent of the inner heliosheath, as affected by solar activity conditions, is thus an additional time-dependent factor to be considered in the long-term modulation of cosmic rays

  14. Systemic resilience model

    International Nuclear Information System (INIS)

    Lundberg, Jonas; Johansson, Björn JE

    2015-01-01

    It has been realized that resilience as a concept involves several contradictory definitions, both for instance resilience as agile adjustment and as robust resistance to situations. Our analysis of resilience concepts and models suggest that beyond simplistic definitions, it is possible to draw up a systemic resilience model (SyRes) that maintains these opposing characteristics without contradiction. We outline six functions in a systemic model, drawing primarily on resilience engineering, and disaster response: anticipation, monitoring, response, recovery, learning, and self-monitoring. The model consists of four areas: Event-based constraints, Functional Dependencies, Adaptive Capacity and Strategy. The paper describes dependencies between constraints, functions and strategies. We argue that models such as SyRes should be useful both for envisioning new resilience methods and metrics, as well as for engineering and evaluating resilient systems. - Highlights: • The SyRes model resolves contradictions between previous resilience definitions. • SyRes is a core model for envisioning and evaluating resilience metrics and models. • SyRes describes six functions in a systemic model. • They are anticipation, monitoring, response, recovery, learning, self-monitoring. • The model describes dependencies between constraints, functions and strategies

  15. Wave-Particle Interactions in the Earth's Radiation Belts: Recent Advances and Unprecedented Future Opportunities

    Science.gov (United States)

    Li, W.

    2017-12-01

    In the collisionless heliospheric plasmas, wave-particle interaction is a fundamental physical process in transferring energy and momentum between particles with different species and energies. This presentation focuses on one of the important wave-particle interaction processes: interaction between whistler-mode waves and electrons. Whistler-mode waves have frequencies between proton and electron cyclotron frequency and are ubiquitously present in the heliospheric plasmas including solar wind and planetary magnetospheres. I use Earth's Van Allen radiation belt as "local space laboratory" to discuss the role of whistler-mode waves in energetic electron dynamics using multi-satellite observations, theory and modeling. I further discuss solar wind drivers leading to energetic electron dynamics in the Earth's radiation belts, which is critical in predicting space weather that has broad impacts on our technological systems and society. At last, I discuss the unprecedented future opportunities of exploring space science using multi-satellite observations and state-of-the-art theory and modeling.

  16. RSMASS system model development

    International Nuclear Information System (INIS)

    Marshall, A.C.; Gallup, D.R.

    1998-01-01

    RSMASS system mass models have been used for more than a decade to make rapid estimates of space reactor power system masses. This paper reviews the evolution of the RSMASS models and summarizes present capabilities. RSMASS has evolved from a simple model used to make rough estimates of space reactor and shield masses to a versatile space reactor power system model. RSMASS uses unique reactor and shield models that permit rapid mass optimization calculations for a variety of space reactor power and propulsion systems. The RSMASS-D upgrade of the original model includes algorithms for the balance of the power system, a number of reactor and shield modeling improvements, and an automatic mass optimization scheme. The RSMASS-D suite of codes cover a very broad range of reactor and power conversion system options as well as propulsion and bimodal reactor systems. Reactor choices include in-core and ex-core thermionic reactors, liquid metal cooled reactors, particle bed reactors, and prismatic configuration reactors. Power conversion options include thermoelectric, thermionic, Stirling, Brayton, and Rankine approaches. Program output includes all major component masses and dimensions, efficiencies, and a description of the design parameters for a mass optimized system. In the past, RSMASS has been used as an aid to identify and select promising concepts for space power applications. The RSMASS modeling approach has been demonstrated to be a valuable tool for guiding optimization of the power system design; consequently, the model is useful during system design and development as well as during the selection process. An improved in-core thermionic reactor system model RSMASS-T is now under development. The current development of the RSMASS-T code represents the next evolutionary stage of the RSMASS models. RSMASS-T includes many modeling improvements and is planned to be more user-friendly. RSMASS-T will be released as a fully documented, certified code at the end of

  17. Development of a Full Ice-cream Cone Model for Halo Coronal Mass Ejections

    Energy Technology Data Exchange (ETDEWEB)

    Na, Hyeonock; Moon, Y.-J.; Lee, Harim, E-mail: nho0512@khu.ac.kr, E-mail: moonyj@khu.ac.kr [School of Space Research, Kyung Hee University, Yongin (Korea, Republic of)

    2017-04-20

    It is essential to determine three-dimensional parameters (e.g., radial speed, angular width, and source location) of coronal mass ejections (CMEs) for the space weather forecast. In this study, we investigate which cone type represents a halo CME morphology using 29 CMEs (12 Solar and Heliospheric Observatory (SOHO) /Large Angle and Spectrometric Coronagraph (LASCO) halo CMEs and 17 Solar Terrestrial Relations Observatory ( STEREO )/Sun–Earth Connection Coronal and Heliospheric Investigation COR2 halo CMEs) from 2010 December to 2011 June. These CMEs are identified as halo CMEs by one spacecraft ( SOHO or one of STEREO A and B ) and limb ones by the other spacecraft (One of STEREO A and B or SOHO ). From cone shape parameters of these CMEs, such as their front curvature, we find that the CME observational structures are much closer to a full ice-cream cone type than a shallow ice-cream cone type. Thus, we develop a full ice-cream cone model based on a new methodology that the full ice-cream cone consists of many flat cones with different heights and angular widths to estimate the three-dimensional parameters of the halo CMEs. This model is constructed by carrying out the following steps: (1) construct a cone for a given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO /LASCO halo CMEs, we find that 3D parameters from our method are similar to those from other stereoscopic methods (i.e., a triangulation method and a Graduated Cylindrical Shell model).

  18. Development of a Full Ice-cream Cone Model for Halo Coronal Mass Ejections

    International Nuclear Information System (INIS)

    Na, Hyeonock; Moon, Y.-J.; Lee, Harim

    2017-01-01

    It is essential to determine three-dimensional parameters (e.g., radial speed, angular width, and source location) of coronal mass ejections (CMEs) for the space weather forecast. In this study, we investigate which cone type represents a halo CME morphology using 29 CMEs (12 Solar and Heliospheric Observatory (SOHO) /Large Angle and Spectrometric Coronagraph (LASCO) halo CMEs and 17 Solar Terrestrial Relations Observatory ( STEREO )/Sun–Earth Connection Coronal and Heliospheric Investigation COR2 halo CMEs) from 2010 December to 2011 June. These CMEs are identified as halo CMEs by one spacecraft ( SOHO or one of STEREO A and B ) and limb ones by the other spacecraft (One of STEREO A and B or SOHO ). From cone shape parameters of these CMEs, such as their front curvature, we find that the CME observational structures are much closer to a full ice-cream cone type than a shallow ice-cream cone type. Thus, we develop a full ice-cream cone model based on a new methodology that the full ice-cream cone consists of many flat cones with different heights and angular widths to estimate the three-dimensional parameters of the halo CMEs. This model is constructed by carrying out the following steps: (1) construct a cone for a given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO /LASCO halo CMEs, we find that 3D parameters from our method are similar to those from other stereoscopic methods (i.e., a triangulation method and a Graduated Cylindrical Shell model).

  19. Development of a Full Ice-cream Cone Model for Halo Coronal Mass Ejections

    Science.gov (United States)

    Na, Hyeonock; Moon, Y.-J.; Lee, Harim

    2017-04-01

    It is essential to determine three-dimensional parameters (e.g., radial speed, angular width, and source location) of coronal mass ejections (CMEs) for the space weather forecast. In this study, we investigate which cone type represents a halo CME morphology using 29 CMEs (12 Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) halo CMEs and 17 Solar Terrestrial Relations Observatory (STEREO)/Sun-Earth Connection Coronal and Heliospheric Investigation COR2 halo CMEs) from 2010 December to 2011 June. These CMEs are identified as halo CMEs by one spacecraft (SOHO or one of STEREO A and B) and limb ones by the other spacecraft (One of STEREO A and B or SOHO). From cone shape parameters of these CMEs, such as their front curvature, we find that the CME observational structures are much closer to a full ice-cream cone type than a shallow ice-cream cone type. Thus, we develop a full ice-cream cone model based on a new methodology that the full ice-cream cone consists of many flat cones with different heights and angular widths to estimate the three-dimensional parameters of the halo CMEs. This model is constructed by carrying out the following steps: (1) construct a cone for a given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO/LASCO halo CMEs, we find that 3D parameters from our method are similar to those from other stereoscopic methods (I.e., a triangulation method and a Graduated Cylindrical Shell model).

  20. The Earth System Model

    Science.gov (United States)

    Schoeberl, Mark; Rood, Richard B.; Hildebrand, Peter; Raymond, Carol

    2003-01-01

    The Earth System Model is the natural evolution of current climate models and will be the ultimate embodiment of our geophysical understanding of the planet. These models are constructed from components - atmosphere, ocean, ice, land, chemistry, solid earth, etc. models and merged together through a coupling program which is responsible for the exchange of data from the components. Climate models and future earth system models will have standardized modules, and these standards are now being developed by the ESMF project funded by NASA. The Earth System Model will have a variety of uses beyond climate prediction. The model can be used to build climate data records making it the core of an assimilation system, and it can be used in OSSE experiments to evaluate. The computing and storage requirements for the ESM appear to be daunting. However, the Japanese ES theoretical computing capability is already within 20% of the minimum requirements needed for some 2010 climate model applications. Thus it seems very possible that a focused effort to build an Earth System Model will achieve succcss.

  1. An ice-cream cone model for coronal mass ejections

    Science.gov (United States)

    Xue, X. H.; Wang, C. B.; Dou, X. K.

    2005-08-01

    In this study, we use an ice-cream cone model to analyze the geometrical and kinematical properties of the coronal mass ejections (CMEs). Assuming that in the early phase CMEs propagate with near-constant speed and angular width, some useful properties of CMEs, namely the radial speed (v), the angular width (α), and the location at the heliosphere, can be obtained considering the geometrical shapes of a CME as an ice-cream cone. This model is improved by (1) using an ice-cream cone to show the near real configuration of a CME, (2) determining the radial speed via fitting the projected speeds calculated from the height-time relation in different azimuthal angles, (3) not only applying to halo CMEs but also applying to nonhalo CMEs.

  2. Human performance modeling for system of systems analytics.

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Kevin R.; Lawton, Craig R.; Basilico, Justin Derrick; Longsine, Dennis E. (INTERA, Inc., Austin, TX); Forsythe, James Chris; Gauthier, John Henry; Le, Hai D.

    2008-10-01

    A Laboratory-Directed Research and Development project was initiated in 2005 to investigate Human Performance Modeling in a System of Systems analytic environment. SAND2006-6569 and SAND2006-7911 document interim results from this effort; this report documents the final results. The problem is difficult because of the number of humans involved in a System of Systems environment and the generally poorly defined nature of the tasks that each human must perform. A two-pronged strategy was followed: one prong was to develop human models using a probability-based method similar to that first developed for relatively well-understood probability based performance modeling; another prong was to investigate more state-of-art human cognition models. The probability-based modeling resulted in a comprehensive addition of human-modeling capability to the existing SoSAT computer program. The cognitive modeling resulted in an increased understanding of what is necessary to incorporate cognition-based models to a System of Systems analytic environment.

  3. Heliophysical Explorers (HELEX): Solar Orbiter and Sentinels - Report of the Joint Science and Technology Definition Team (JSTDT)

    Science.gov (United States)

    2008-01-01

    Heliophysical Explorers (HELEX) brings together and augments the unique capabilities of ESA's Solar Orbiter mission (near-Sun and out-of-ecliptic in-situ plus remote-sensing observations) with those of NASA's Inner Heliospheric Sentinels (in-situ observations from multiple platforms arrayed at varying radial distances and azimuthal locations in the near-ecliptic plane)to investigate, characterize, and understand how the Sun determines the environment of the inner solar system and, more broadly, generates the heliosphere itself. This joint ESA-NASA science program offers a unique opportunity for coordinated, correlative measurements, resulting in a combined observational capability and science return that far outweighs that of either mission alone. Building on the knowledge gained from missions like Helios and Ulysses, and STEREO, HELEX will bring to bear the power of multipoint, in-situ measurements using previously unavailable instrumental capabilities in combination with remote-sensing observations from a new, inner heliospheric perspective to answer fundamental questions about the Sun-heliosphere linkage.

  4. Optimization of large-scale heterogeneous system-of-systems models.

    Energy Technology Data Exchange (ETDEWEB)

    Parekh, Ojas; Watson, Jean-Paul; Phillips, Cynthia Ann; Siirola, John; Swiler, Laura Painton; Hough, Patricia Diane (Sandia National Laboratories, Livermore, CA); Lee, Herbert K. H. (University of California, Santa Cruz, Santa Cruz, CA); Hart, William Eugene; Gray, Genetha Anne (Sandia National Laboratories, Livermore, CA); Woodruff, David L. (University of California, Davis, Davis, CA)

    2012-01-01

    Decision makers increasingly rely on large-scale computational models to simulate and analyze complex man-made systems. For example, computational models of national infrastructures are being used to inform government policy, assess economic and national security risks, evaluate infrastructure interdependencies, and plan for the growth and evolution of infrastructure capabilities. A major challenge for decision makers is the analysis of national-scale models that are composed of interacting systems: effective integration of system models is difficult, there are many parameters to analyze in these systems, and fundamental modeling uncertainties complicate analysis. This project is developing optimization methods to effectively represent and analyze large-scale heterogeneous system of systems (HSoS) models, which have emerged as a promising approach for describing such complex man-made systems. These optimization methods enable decision makers to predict future system behavior, manage system risk, assess tradeoffs between system criteria, and identify critical modeling uncertainties.

  5. Selected System Models

    Science.gov (United States)

    Schmidt-Eisenlohr, F.; Puñal, O.; Klagges, K.; Kirsche, M.

    Apart from the general issue of modeling the channel, the PHY and the MAC of wireless networks, there are specific modeling assumptions that are considered for different systems. In this chapter we consider three specific wireless standards and highlight modeling options for them. These are IEEE 802.11 (as example for wireless local area networks), IEEE 802.16 (as example for wireless metropolitan networks) and IEEE 802.15 (as example for body area networks). Each section on these three systems discusses also at the end a set of model implementations that are available today.

  6. Response times of Cassini/INCA > 5.2 keV ENAs and Voyager ions in the heliosheath over the solar cycle

    Science.gov (United States)

    Dialynas, K.; Krimigis, S. M.; Mitchell, D. G.; Decker, R. B.; Roelof, E. C.

    2017-09-01

    Both a magnetosphere-like tail and a bubble model of the heliosphere were posited by E. N. Parker in 1961. Recently, we showed that heliosheath ions are the source of > 5.2 keV Energetic Neutral Atoms (ENA), whose images of the heliosphere exhibit a rough nose to anti-nose (tail) global symmetry that resembles a diamagnetic bubble. The comparison between energetic neutral atom (ENA) global images of the helioshphere obtained with the Ion and Neutral Camera (INCA) on board Cassini and ions measured in-situ by the Low Energy Charged Particle experiment (LECP) on board Voyager 1 and 2 (V1/V2) in overlapping energy bands over an 11-year period shows that the heliosphere responds promptly, within ∼2-3 years, to outward propagating solar wind changes in both the nose and tail directions. Here we focus on the recovery of solar cycle 24 and the response times of > 5.2 keV ENAs to show that this ∼2-3-year time delay is consistent with a “tail” of ∼80-120 AU. This preliminary rough calculation is generally consistent with lower energy ENA data (E < 6 keV, from the IBEX-Lo and IBEX-Hi) and is supported by recent modelling of the heliosphere.

  7. A Numerical Study of Forbush Decreases with a 3D Cosmic-Ray Modulation Model Based on an SDE Approach

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xi; Feng, Xueshang [SIGMA Weather Group, State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Potgieter, Marius S. [Centre for Space Research, North-West University, Potchefstroom 2520 (South Africa); Zhang, Ming [Department of Physics and Space Sciences, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States)

    2017-04-10

    Based on the reduced diffusion mechanism for producing Forbush decreases (Fds) in the heliosphere, we constructed a three-dimensional (3D) diffusion barrier, and by incorporating it into a stochastic differential equation (SDE) based time-dependent, cosmic-ray transport model, a 3D numerical model for simulating Fds is built and applied to a period of relatively quiet solar activity. This SDE model generally corroborates previous Fd simulations concerning the effects of the solar magnetic polarity, the tilt angle of the heliospheric current sheet (HCS), and cosmic-ray particle energy. Because the modulation processes in this 3D model are multi-directional, the barrier’s geometrical features affect the intensity profiles of Fds differently. We find that both the latitudinal and longitudinal extent of the barrier have relatively fewer effects on these profiles than its radial extent and the level of decreased diffusion inside the disturbance. We find, with the 3D approach, that the HCS rotational motion causes the relative location from the observation point to the HCS to vary, so that a periodic pattern appears in the cosmic-ray intensity at the observing location. Correspondingly, the magnitude and recovery time of an Fd change, and the recovering intensity profile contains oscillation as well. Investigating the Fd magnitude variation with heliocentric radial distance, we find that the magnitude decreases overall and, additionally, that the Fd magnitude exhibits an oscillating pattern as the radial distance increases, which coincides well with the wavy profile of the HCS under quiet solar modulation conditions.

  8. Modeller af komplicerede systemer

    DEFF Research Database (Denmark)

    Mortensen, J.

    emphasizes their use in relation to technical systems. All the presented models, with the exception of the types presented in chapter 2, are non-theoretical non-formal conceptual network models. Two new model types are presented: 1) The System-Environment model, which describes the environments interaction...... with conceptual modeling in relation to process control. It´s purpose is to present classify and exemplify the use of a set of qualitative model types. Such model types are useful in the early phase of modeling, where no structured methods are at hand. Although the models are general in character, this thesis......This thesis, "Modeller af komplicerede systemer", represents part of the requirements for the Danish Ph.D.degree. Assisting professor John Nørgaard-Nielsen, M.Sc.E.E.Ph.D. has been principal supervisor and professor Morten Lind, M.Sc.E.E.Ph.D. has been assisting supervisor. The thesis is concerned...

  9. Modeling Novo Nordisk Production Systems

    DEFF Research Database (Denmark)

    Miller, Thomas Dedenroth

    1997-01-01

    This report describes attributes of models and systems, and how models can be used for description of production systems. There are special attention on the 'Theory of Domains'.......This report describes attributes of models and systems, and how models can be used for description of production systems. There are special attention on the 'Theory of Domains'....

  10. The modulation of galactic cosmic rays as described by a three-dimensional drift model

    International Nuclear Information System (INIS)

    Potgieter, M.S.

    1984-01-01

    An outline of the present state of knowledge about the effect of drift on the modulation of galactic cosmic rays is given. Various observations related to the reversal of the solar magnetic field polarity are discussed. Comprehensive numerical solutions of the steady-state cosmic-ray transport equation in an axially-symmetric three-dimensional heliosphere, including drift are presented. This is an extention of the continuing effort of the past six years to understand the effect and importance of drift on the transport of galactic cosmic rays in the heliosphere. A flat neutral sheet which coincides with the equatorial plane is assumed. A general method of calculating the drift velocity in the neutral sheet including that used previously by other authors is presented. The effect of changing various modulation parameters on the drift solutions are illustrated in detail. The real significance of drift is illustrated by using Gaussian input spectra on the modulation boundary. A carefully selected set of modulation parameters is used to illustrate to what extent a drift model can explain prominent observational features. It is concluded that drift is important in in the process of cosmic-ray transport and must as such be considered in all modulation studies, but that it is not overwhelmingly dominant as previously anticipated

  11. Halo-coronal mass ejections near the 23rd solar minimum: lift-off, inner heliosphere, and in situ (1 AU signatures

    Directory of Open Access Journals (Sweden)

    D. B. Berdichevsky

    2002-07-01

    Full Text Available The extreme ultraviolet (EUV signatures of a solar lift-off, decametric and kilometric radio burst emissions and energetic particle (EP inner heliospheric signatures of an interplanetary shock, and in situ identification of its driver through solar wind observations are discussed for 12 isolated halo coronal mass ejections (H-CMEs occurring between December 1996 and 1997. For the aforementioned twelve and the one event added in the discussion, it is found that ten passed several necessary conditions for being a "Sun-Earth connection". It is found that low corona EUV and Ha chromospheric signatures indicate filament eruption as the cause of H-CME. These signatures indicate that the 12 events can be divided into two major subsets, 7 related to active regions (ARs and 5 unrelated or related to decayed AR. In the case of events related to AR, there is indication of a faster lift-off, while a more gradual lift-off appears to characterize the second set. Inner heliospheric signatures – the presence of long lasting enhanced energetic particle flux and/or kilometric type II radio bursts – of a driven shock were identified in half of the 12 events. The in situ (1 AU analyses using five different solar wind ejecta signatures and comparisons with the bidirectional flow of suprathermal particles and Forbush decreases result in indications of a strong solar wind ejecta signatures for 11 out of 12 cases. From the discussion of these results, combined with work by other authors for overlapping events, we conclude that good Sun-Earth connection candidates originate most likely from solar filament eruptions with at least one of its extremities located closer to the central meridian than ~ 30° E or ~ 35° W with a larger extension in latitudinal location possible. In seven of the twelve cases it appears that the encountered ejecta was driving a shock at 1 AU. Support for this interpretation is found on the approximately equal velocity of the shock and the

  12. Halo-coronal mass ejections near the 23rd solar minimum: lift-off, inner heliosphere, and in situ (1 AU signatures

    Directory of Open Access Journals (Sweden)

    D. B. Berdichevsky

    Full Text Available The extreme ultraviolet (EUV signatures of a solar lift-off, decametric and kilometric radio burst emissions and energetic particle (EP inner heliospheric signatures of an interplanetary shock, and in situ identification of its driver through solar wind observations are discussed for 12 isolated halo coronal mass ejections (H-CMEs occurring between December 1996 and 1997. For the aforementioned twelve and the one event added in the discussion, it is found that ten passed several necessary conditions for being a "Sun-Earth connection". It is found that low corona EUV and Ha chromospheric signatures indicate filament eruption as the cause of H-CME. These signatures indicate that the 12 events can be divided into two major subsets, 7 related to active regions (ARs and 5 unrelated or related to decayed AR. In the case of events related to AR, there is indication of a faster lift-off, while a more gradual lift-off appears to characterize the second set. Inner heliospheric signatures – the presence of long lasting enhanced energetic particle flux and/or kilometric type II radio bursts – of a driven shock were identified in half of the 12 events. The in situ (1 AU analyses using five different solar wind ejecta signatures and comparisons with the bidirectional flow of suprathermal particles and Forbush decreases result in indications of a strong solar wind ejecta signatures for 11 out of 12 cases. From the discussion of these results, combined with work by other authors for overlapping events, we conclude that good Sun-Earth connection candidates originate most likely from solar filament eruptions with at least one of its extremities located closer to the central meridian than ~ 30° E or ~ 35° W with a larger extension in latitudinal location possible. In seven of the twelve cases it appears that the encountered ejecta was driving a shock at 1 AU. Support for this interpretation is found on the approximately equal

  13. Modeling Complex Systems

    International Nuclear Information System (INIS)

    Schreckenberg, M

    2004-01-01

    This book by Nino Boccara presents a compilation of model systems commonly termed as 'complex'. It starts with a definition of the systems under consideration and how to build up a model to describe the complex dynamics. The subsequent chapters are devoted to various categories of mean-field type models (differential and recurrence equations, chaos) and of agent-based models (cellular automata, networks and power-law distributions). Each chapter is supplemented by a number of exercises and their solutions. The table of contents looks a little arbitrary but the author took the most prominent model systems investigated over the years (and up until now there has been no unified theory covering the various aspects of complex dynamics). The model systems are explained by looking at a number of applications in various fields. The book is written as a textbook for interested students as well as serving as a comprehensive reference for experts. It is an ideal source for topics to be presented in a lecture on dynamics of complex systems. This is the first book on this 'wide' topic and I have long awaited such a book (in fact I planned to write it myself but this is much better than I could ever have written it!). Only section 6 on cellular automata is a little too limited to the author's point of view and one would have expected more about the famous Domany-Kinzel model (and more accurate citation!). In my opinion this is one of the best textbooks published during the last decade and even experts can learn a lot from it. Hopefully there will be an actualization after, say, five years since this field is growing so quickly. The price is too high for students but this, unfortunately, is the normal case today. Nevertheless I think it will be a great success! (book review)

  14. An online model composition tool for system biology models.

    Science.gov (United States)

    Coskun, Sarp A; Cicek, A Ercument; Lai, Nicola; Dash, Ranjan K; Ozsoyoglu, Z Meral; Ozsoyoglu, Gultekin

    2013-09-05

    There are multiple representation formats for Systems Biology computational models, and the Systems Biology Markup Language (SBML) is one of the most widely used. SBML is used to capture, store, and distribute computational models by Systems Biology data sources (e.g., the BioModels Database) and researchers. Therefore, there is a need for all-in-one web-based solutions that support advance SBML functionalities such as uploading, editing, composing, visualizing, simulating, querying, and browsing computational models. We present the design and implementation of the Model Composition Tool (Interface) within the PathCase-SB (PathCase Systems Biology) web portal. The tool helps users compose systems biology models to facilitate the complex process of merging systems biology models. We also present three tools that support the model composition tool, namely, (1) Model Simulation Interface that generates a visual plot of the simulation according to user's input, (2) iModel Tool as a platform for users to upload their own models to compose, and (3) SimCom Tool that provides a side by side comparison of models being composed in the same pathway. Finally, we provide a web site that hosts BioModels Database models and a separate web site that hosts SBML Test Suite models. Model composition tool (and the other three tools) can be used with little or no knowledge of the SBML document structure. For this reason, students or anyone who wants to learn about systems biology will benefit from the described functionalities. SBML Test Suite models will be a nice starting point for beginners. And, for more advanced purposes, users will able to access and employ models of the BioModels Database as well.

  15. Introducing Model-Based System Engineering Transforming System Engineering through Model-Based Systems Engineering

    Science.gov (United States)

    2014-03-31

    Web  Presentation...Software  .....................................................  20   Figure  6.  Published   Web  Page  from  Data  Collection...the  term  Model  Based  Engineering  (MBE),  Model  Driven  Engineering  ( MDE ),  or  Model-­‐Based  Systems  

  16. First Asia-Pacific Regional School of the International Heliophysical Year (IHY) 2007 program

    CERN Document Server

    Gopalswamy, Natchimuthuk; Ambastha, Ashok; Heliophysical Processes

    2010-01-01

    An outgrowth of the first Asia-Pacific Regional School on the International Heliophysical Year (IHY), this volume contains a collection of review articles describing the universal physical processes in the heliospace influenced by solar electromagnetic and mass emissions. The Sun affects the heliosphere in the short term (space weather) and in the long term (space climate) through numerous physical processes that exhibit similarities in various spatial domains of the heliosphere. The articles take into account various aspects of the Sun-heliosphere connection under a systems approach. This volume will serve as a ready reference work for research in the emerging field of heliophysics, which describes the physical processes taking place in the physical space controlled by the Sun out to the local interstellar medium.

  17. Heliophysics: The New Science of the Sun-Solar System Connection. Recommended Roadmap for Science and Technology 2005-2035

    Science.gov (United States)

    2005-01-01

    This is a Roadmap to understanding the environment of our Earth, from its life-sustaining Sun out past the frontiers of the solar system. A collection of spacecraft now patrols this space, revealing not a placid star and isolated planets, but an immense, dynamic, interconnected system within which our home planet is embedded and through which space explorers must journey. These spacecraft already form a great observatory with which the Heliophysics program can study the Sun, the heliosphere, the Earth, and other planetary environments as elements of a system--one that contains dynamic space weather and evolves in response to solar, planetary, and interstellar variability. NASA continually evolves the Heliophysics Great Observatory by adding new missions and instruments in order to answer the challenging questions confronting us now and in the future as humans explore the solar system. The three heliophysics science objectives: opening the frontier to space environment prediction; understanding the nature of our home in space, and safeguarding the journey of exploration, require sustained research programs that depend on combining new data, theory, analysis, simulation, and modeling. Our program pursues a deeper understanding of the fundamental physical processes that underlie the exotic phenomena of space.

  18. Empirical Modeling of ICMEs Using ACE/SWICS Ionic Distributions

    Science.gov (United States)

    Rivera, Y.; Landi, E.; Lepri, S. T.; Gilbert, J. A.

    2017-12-01

    Coronal Mass Ejections (CMEs) are some of the largest, most energetic events in the solar system releasing an immense amount of plasma and magnetic field into the Heliosphere. The Earth-bound plasma plays a large role in space weather, causing geomagnetic storms that can damage space and ground based instrumentation. As a CME is released, the plasma experiences heating, expansion and acceleration; however, the physical mechanism supplying the heating as it lifts out of the corona still remains uncertain. From previous work we know the ionic composition of solar ejecta undergoes a gradual transition to a state where ionization and recombination processes become ineffective rendering the ionic composition static along its trajectory. This property makes them a good indicator of thermal conditions in the corona, where the CME plasma likely receives most of its heating. We model this so-called `freeze-in' process in Earth-directed CMEs using an ionization code to empirically determine the electron temperature, density and bulk velocity. `Frozen-in' ions from an ensemble of independently modeled plasmas within the CME are added together to fit the full range of observational ionic abundances collected by ACE/SWICS during ICME events. The models derived using this method are used to estimate the CME energy budget to determine a heating rate used to compare with a variety of heating mechanisms that can sustain the required heating with a compatible timescale.

  19. Particle Tracking Model (PTM) with Coastal Modeling System (CMS)

    Science.gov (United States)

    2015-11-04

    Coastal Inlets Research Program Particle Tracking Model (PTM) with Coastal Modeling System ( CMS ) The Particle Tracking Model (PTM) is a Lagrangian...currents and waves. The Coastal Inlets Research Program (CIRP) supports the PTM with the Coastal Modeling System ( CMS ), which provides coupled wave...and current forcing for PTM simulations. CMS -PTM is implemented in the Surface-water Modeling System, a GUI environment for input development

  20. Using the Model Coupling Toolkit to couple earth system models

    Science.gov (United States)

    Warner, J.C.; Perlin, N.; Skyllingstad, E.D.

    2008-01-01

    Continued advances in computational resources are providing the opportunity to operate more sophisticated numerical models. Additionally, there is an increasing demand for multidisciplinary studies that include interactions between different physical processes. Therefore there is a strong desire to develop coupled modeling systems that utilize existing models and allow efficient data exchange and model control. The basic system would entail model "1" running on "M" processors and model "2" running on "N" processors, with efficient exchange of model fields at predetermined synchronization intervals. Here we demonstrate two coupled systems: the coupling of the ocean circulation model Regional Ocean Modeling System (ROMS) to the surface wave model Simulating WAves Nearshore (SWAN), and the coupling of ROMS to the atmospheric model Coupled Ocean Atmosphere Prediction System (COAMPS). Both coupled systems use the Model Coupling Toolkit (MCT) as a mechanism for operation control and inter-model distributed memory transfer of model variables. In this paper we describe requirements and other options for model coupling, explain the MCT library, ROMS, SWAN and COAMPS models, methods for grid decomposition and sparse matrix interpolation, and provide an example from each coupled system. Methods presented in this paper are clearly applicable for coupling of other types of models. ?? 2008 Elsevier Ltd. All rights reserved.

  1. A stream-based mathematical model for distributed information processing systems - SysLab system model

    OpenAIRE

    Klein, Cornel; Rumpe, Bernhard; Broy, Manfred

    2014-01-01

    In the SysLab project we develop a software engineering method based on a mathematical foundation. The SysLab system model serves as an abstract mathematical model for information systems and their components. It is used to formalize the semantics of all used description techniques such as object diagrams state automata sequence charts or data-flow diagrams. Based on the requirements for such a reference model, we define the system model including its different views and their relationships.

  2. Modeling aluminum-air battery systems

    Science.gov (United States)

    Savinell, R. F.; Willis, M. S.

    The performance of a complete aluminum-air battery system was studied with a flowsheet model built from unit models of each battery system component. A plug flow model for heat transfer was used to estimate the amount of heat transferred from the electrolyte to the air stream. The effect of shunt currents on battery performance was found to be insignificant. Using the flowsheet simulator to analyze a 100 cell battery system now under development demonstrated that load current, aluminate concentration, and electrolyte temperature are dominant variables controlling system performance. System efficiency was found to decrease as both load current and aluminate concentration increases. The flowsheet model illustrates the interdependence of separate units on overall system performance.

  3. Modeling Complex Systems

    CERN Document Server

    Boccara, Nino

    2010-01-01

    Modeling Complex Systems, 2nd Edition, explores the process of modeling complex systems, providing examples from such diverse fields as ecology, epidemiology, sociology, seismology, and economics. It illustrates how models of complex systems are built and provides indispensable mathematical tools for studying their dynamics. This vital introductory text is useful for advanced undergraduate students in various scientific disciplines, and serves as an important reference book for graduate students and young researchers. This enhanced second edition includes: . -recent research results and bibliographic references -extra footnotes which provide biographical information on cited scientists who have made significant contributions to the field -new and improved worked-out examples to aid a student’s comprehension of the content -exercises to challenge the reader and complement the material Nino Boccara is also the author of Essentials of Mathematica: With Applications to Mathematics and Physics (Springer, 2007).

  4. Imprint of the Sun’s Evolving Polar Winds on IBEX Energetic Neutral Atom All-sky Observations of the Heliosphere

    Energy Technology Data Exchange (ETDEWEB)

    Zirnstein, E. J.; McComas, D. J. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Dayeh, M. A. [Southwest Research Institute, San Antonio, TX 78228 (United States); Sokół, J. M., E-mail: ejz@princeton.edu [Space Research Centre of the Polish Academy of Sciences, 00-716 Warsaw (Poland)

    2017-09-01

    With 7 years of Interstellar Boundary Explorer ( IBEX ) measurements of energetic neutral atoms (ENAs), IBEX has shown a clear correlation between dynamic changes in the solar wind and the heliosphere’s response in the formation of ENAs. In this paper, we investigate temporal variations in the latitudinal-dependent ENA spectrum from IBEX and their relationship to the solar wind speed observed at 1 au. We find that the variation in latitude of the transition in ENA spectral indices between low (≲1.8) and high (≳1.8) values, as well as the distribution of ENA spectral indices at high and low latitudes, correlates well with the evolution of the fast and slow solar wind latitudinal structure observed near 1 au. This correlation includes a delay due to the time it takes the solar wind to propagate to the termination shock and into the inner heliosheath, and for ENAs to be generated via charge-exchange and travel back toward 1 au. Moreover, we observe a temporal asymmetry in the steepening of the ENA spectrum in the northern and southern hemispheres, consistent with asymmetries observed in the solar wind and polar coronal holes. While this asymmetry is observed near the upwind direction of the heliosphere, it is not yet observed in the tail direction, suggesting a longer line-of-sight integration distance or different processing of the solar wind plasma downstream of the termination shock.

  5. Inflight performance of the Ulysses reaction control system

    Science.gov (United States)

    McGarry, Andrew; Berry, William; Parker, David

    1997-01-01

    The Ulysses spacecraft has been exploring the heliosphere since October 1990 in a six-year polar orbit. Despite varying operational demands, the pressure-fed monopropellant hydrazine reaction control system (RCS) has experienced few problems. The observed anomalies, having minimal operational impact, include plume impingement effects, electrical power overload effects and hydrazine gas generation effects. These anomalies are presented and discussed, with emphasis on the first observation of gas in the hydrazine propellant. The relatively low gas generation rate is attributed to: the use of high purity hydrazine; the configuration of the spin-stabilized spacecraft; the extensive use of titanium alloys; and the efficiency of the thermal control of the propellant tank which maintains a temperature of 21 C.

  6. Watershed System Model: The Essentials to Model Complex Human-Nature System at the River Basin Scale

    Science.gov (United States)

    Li, Xin; Cheng, Guodong; Lin, Hui; Cai, Ximing; Fang, Miao; Ge, Yingchun; Hu, Xiaoli; Chen, Min; Li, Weiyue

    2018-03-01

    Watershed system models are urgently needed to understand complex watershed systems and to support integrated river basin management. Early watershed modeling efforts focused on the representation of hydrologic processes, while the next-generation watershed models should represent the coevolution of the water-land-air-plant-human nexus in a watershed and provide capability of decision-making support. We propose a new modeling framework and discuss the know-how approach to incorporate emerging knowledge into integrated models through data exchange interfaces. We argue that the modeling environment is a useful tool to enable effective model integration, as well as create domain-specific models of river basin systems. The grand challenges in developing next-generation watershed system models include but are not limited to providing an overarching framework for linking natural and social sciences, building a scientifically based decision support system, quantifying and controlling uncertainties, and taking advantage of new technologies and new findings in the various disciplines of watershed science. The eventual goal is to build transdisciplinary, scientifically sound, and scale-explicit watershed system models that are to be codesigned by multidisciplinary communities.

  7. Modeling the earth system

    Energy Technology Data Exchange (ETDEWEB)

    Ojima, D. [ed.

    1992-12-31

    The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.

  8. Modeling cellular systems

    CERN Document Server

    Matthäus, Franziska; Pahle, Jürgen

    2017-01-01

    This contributed volume comprises research articles and reviews on topics connected to the mathematical modeling of cellular systems. These contributions cover signaling pathways, stochastic effects, cell motility and mechanics, pattern formation processes, as well as multi-scale approaches. All authors attended the workshop on "Modeling Cellular Systems" which took place in Heidelberg in October 2014. The target audience primarily comprises researchers and experts in the field, but the book may also be beneficial for graduate students.

  9. Validation of Embedded System Verification Models

    NARCIS (Netherlands)

    Marincic, J.; Mader, Angelika H.; Wieringa, Roelf J.

    The result of a model-based requirements verification shows that the model of a system satisfies (or not) formalised system requirements. The verification result is correct only if the model represents the system adequately. No matter what modelling technique we use, what precedes the model

  10. Environmental Impact Specification for Direct Space Weathering of Kuiper Belt and Oort Cloud Objects

    Science.gov (United States)

    Cooper, John F.

    2010-01-01

    The Direct Space Weathering Project of NASA's Outer Planets Research Program addresses specification of the plasma and energetic particle environments for irradiation and surface chemical processing of icy bodies in the outer solar system and the local interstellar medium. Knowledge of the radiation environments is being expanded by ongoing penetration of the twin Voyager spacecraft into the heliosheath boundary region of the outer heliosphere and expected emergence within the next decade into the very local interstellar medium. The Voyager measurements are being supplemented by remote sensing from Earth orbit of energetic neutral atom emission from this boundary region by NASA's Interstellar Boundary Explorer (IBEX). Although the Voyagers long ago passed the region of the Classical Kuiper Belt, the New Horizons spacecraft will encounter Pluto in 2015 and thereafter explore one or more KBOs, meanwhile providing updated measurements of the heliospheric radiation environment in this region. Modeling of ion transport within the heliosphere allows specification of time-integrated irradiation effects while the combination of Voyager and IBEX data supports projection of the in-situ measurements into interstellar space beyond the heliosheath. Transformation of model ion flux distributions into surface sputtering and volume ionization profiles provides a multi-layer perspective for space weathering impact on the affected icy bodies and may account for some aspects of color and compositional diversity. Other important related factors may include surface erosion and gardening by meteoritic impacts and surface renewal by cryovolcanism. Chemical products of space weathering may contribute to energy resources for the latter.

  11. Advancing coupled human-earth system models: The integrated Earth System Model Project

    Science.gov (United States)

    Thomson, A. M.; Edmonds, J. A.; Collins, W.; Thornton, P. E.; Hurtt, G. C.; Janetos, A. C.; Jones, A.; Mao, J.; Chini, L. P.; Calvin, K. V.; Bond-Lamberty, B. P.; Shi, X.

    2012-12-01

    As human and biogeophysical models develop, opportunities for connections between them evolve and can be used to advance our understanding of human-earth systems interaction in the context of a changing climate. One such integration is taking place with the Community Earth System Model (CESM) and the Global Change Assessment Model (GCAM). A multi-disciplinary, multi-institution team has succeeded in integrating the GCAM integrated assessment model of human activity into CESM to dynamically represent the feedbacks between changing climate and human decision making, in the context of greenhouse gas mitigation policies. The first applications of this capability have focused on the feedbacks between climate change impacts on terrestrial ecosystem productivity and human decisions affecting future land use change, which are in turn connected to human decisions about energy systems and bioenergy production. These experiments have been conducted in the context of the RCP4.5 scenario, one of four pathways of future radiative forcing being used in CMIP5, which constrains future human-induced greenhouse gas emissions from energy and land activities to stabilize radiative forcing at 4.5 W/m2 (~650 ppm CO2 -eq) by 2100. When this pathway is run in GCAM with the climate feedback on terrestrial productivity from CESM, there are implications for both the land use and energy system changes required for stabilization. Early findings indicate that traditional definitions of radiative forcing used in scenario development are missing a critical component of the biogeophysical consequences of land use change and their contribution to effective radiative forcing. Initial full coupling of the two global models has important implications for how climate impacts on terrestrial ecosystems changes the dynamics of future land use change for agriculture and forestry, particularly in the context of a climate mitigation policy designed to reduce emissions from land use as well as energy systems

  12. Pembangunan Model Restaurant Management System

    OpenAIRE

    Fredy Jingga; Natalia Limantara

    2014-01-01

    Model design for Restaurant Management System aims to help in restaurant business process, where Restaurant Management System (RMS) help the waitress and chef could interact each other without paper limitation.  This Restaurant Management System Model develop using Agile Methodology and developed based on PHP Programming Langguage. The database management system is using MySQL. This web-based application model will enable the waitress and the chef to interact in realtime, from the time they a...

  13. Properties of the Plasma Surrounding the Global Heliosphere Determined with Voyager 1&2 ions and ENA/INCA Observations at E > 5 keV

    Science.gov (United States)

    Krimigis, S. M.; Dialynas, K.; Mitchell, D. G.; Decker, R. B.; Roelof, E. C.

    2016-12-01

    The basic goal of the proposed Interstellar Mapping and Acceleration Probe (IMAP) is detailed scientific understanding of the Heliosheath (HS) and beyond, a region of space explored in situ by Voyager 1 (V1) since 2004, Voyager 2 (V2) since 2007, and remotely via energetic neutral atoms (ENA) by the Cassini/INCA (5.2-55 keV) since 2003 and IBEX (0.3-6 keV) since 2009. The partial overlap in energies (28 5 keV, the rest residing below that range, resulting in a beta (particle/magnetic pressure) always > 1, typically >10. (2) Based on the ENA-derived hot ion pressures, the interstellar magnetic field (ISMF) was predicted to be more than twice that expected in the literature i.e. similar to what was measured by V1 after crossing the heliopause (B 0.5 nT). (3) The width of the HS in the direction of V1 is 30 AU (predicted by INCA before the V1 HP crossing), but is thought to be larger (40-70 AU) in the southern ecliptic where V2, now 30 AU into the HS, currently travels. We address here the key question of the source of 5-55 keV ENAs that INCA measures. The analysis of INCA all-sky maps from 2003 to 2014 show that the decrease and recovery of ENA in the global heliosphere during this period (declining phase of SC23 and rise of SC24) is similar to that of the ions at V1/V2, consistent with the HS ions being the source of ENA. The close correspondence between ENA and ion spectra (despite the 140 AU distance between V1 and V2) as well as the similarity of ENA spectra over the nose and anti-nose directions, together with the recent V1 measurement of a BISMF 0.5nT, suggest that the global distributions of >5 keV ions in the heliosheath resembles a diamagnetic bubble with no significant tail-like feature (the alternative Parker 1961 model), also consistent with some recent MHD simulations and models.

  14. Interstellar Mapping and Acceleration Probe (IMAP)

    International Nuclear Information System (INIS)

    Schwadron, N. A.; Moebius, E.; Spence, H. E.; Opher, M.; Kasper, J.; Zurbuchen, T. H.; Mewaldt, R.

    2016-01-01

    Our piece of cosmic real estate, the heliosphere, is the domain of all human existence – an astrophysical case history of the successful evolution of life in a habitable system. By exploring our global heliosphere and its myriad interactions, we develop key physical knowledge of the interstellar interactions that influence exoplanetary habitability as well as the distant history and destiny of our solar system and world. IBEX is the first mission to explore the global heliosphere and in concert with Voyager 1 and Voyager 2 is discovering a fundamentally new and uncharted physical domain of the outer heliosphere. In parallel, Cassini/INCA maps the global heliosphere at energies (∼5-55 keV) above those measured by IBEX. The enigmatic IBEX ribbon and the INCA belt were unanticipated discoveries demonstrating that much of what we know or think we understand about the outer heliosphere needs to be revised. This paper summarizes the next quantum leap enabled by IMAP that will open new windows on the frontier of Heliophysics at a time when the space environment is rapidly evolving. IMAP with 100 times the combined resolution and sensitivity of IBEX and INCA will discover the substructure of the IBEX ribbon and will reveal, with unprecedented resolution, global maps of our heliosphere. The remarkable synergy between IMAP, Voyager 1 and Voyager 2 will remain for at least the next decade as Voyager 1 pushes further into the interstellar domain and Voyager 2 moves through the heliosheath. Voyager 2 moves outward in the same region of sky covered by a portion of the IBEX ribbon. Voyager 2’s plasma measurements will create singular opportunities for discovery in the context of IMAP's global measurements. IMAP, like ACE before, will be a keystone of the Heliophysics System Observatory by providing comprehensive measurements of interstellar neutral atoms and pickup ions, the solar wind distribution, composition, and magnetic field, as well as suprathermal ion

  15. On Modelling an Immune System

    OpenAIRE

    Monroy, Raúl; Saab, Rosa; Godínez, Fernando

    2004-01-01

    Immune systems of live forms have been an abundant source of inspiration to contemporary computer scientists. Problem solving strategies, stemming from known immune system phenomena, have been successfully applied to challenging problems of modern computing. However, research in artificial immune systems has overlooked establishing a coherent model of known immune system behaviour. This paper aims reports on an preliminary computer model of an immune system, where each immune system component...

  16. Multiple system modelling of waste management

    International Nuclear Information System (INIS)

    Eriksson, Ola; Bisaillon, Mattias

    2011-01-01

    Highlights: → Linking of models will provide a more complete, correct and credible picture of the systems. → The linking procedure is easy to perform and also leads to activation of project partners. → The simulation procedure is a bit more complicated and calls for the ability to run both models. - Abstract: Due to increased environmental awareness, planning and performance of waste management has become more and more complex. Therefore waste management has early been subject to different types of modelling. Another field with long experience of modelling and systems perspective is energy systems. The two modelling traditions have developed side by side, but so far there are very few attempts to combine them. Waste management systems can be linked together with energy systems through incineration plants. The models for waste management can be modelled on a quite detailed level whereas surrounding systems are modelled in a more simplistic way. This is a problem, as previous studies have shown that assumptions on the surrounding system often tend to be important for the conclusions. In this paper it is shown how two models, one for the district heating system (MARTES) and another one for the waste management system (ORWARE), can be linked together. The strengths and weaknesses with model linking are discussed when compared to simplistic assumptions on effects in the energy and waste management systems. It is concluded that the linking of models will provide a more complete, correct and credible picture of the consequences of different simultaneous changes in the systems. The linking procedure is easy to perform and also leads to activation of project partners. However, the simulation procedure is a bit more complicated and calls for the ability to run both models.

  17. Transforming Graphical System Models to Graphical Attack Models

    DEFF Research Database (Denmark)

    Ivanova, Marieta Georgieva; Probst, Christian W.; Hansen, Rene Rydhof

    2016-01-01

    Manually identifying possible attacks on an organisation is a complex undertaking; many different factors must be considered, and the resulting attack scenarios can be complex and hard to maintain as the organisation changes. System models provide a systematic representation of organisations...... approach to transforming graphical system models to graphical attack models in the form of attack trees. Based on an asset in the model, our transformations result in an attack tree that represents attacks by all possible actors in the model, after which the actor in question has obtained the asset....

  18. A Model-Based Systems Engineering Methodology for Employing Architecture In System Analysis: Developing Simulation Models Using Systems Modeling Language Products to Link Architecture and Analysis

    Science.gov (United States)

    2016-06-01

    18 Figure 5 Spiral Model ...............................................................................................20 Figure 6...Memorandum No. 1. Tallahassee, FL: Florida Department of Transportation. 19 The spiral model of system development, first introduced in Boehm...system capabilities into the waterfall model would prove quite difficult, the spiral model assumes that available technologies will change over the

  19. HELIOSPHERIC PROPAGATION OF CORONAL MASS EJECTIONS: COMPARISON OF NUMERICAL WSA-ENLIL+CONE MODEL AND ANALYTICAL DRAG-BASED MODEL

    Energy Technology Data Exchange (ETDEWEB)

    Vršnak, B.; Žic, T.; Dumbović, M. [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kačćeva 26, HR-10000 Zagreb (Croatia); Temmer, M.; Möstl, C.; Veronig, A. M. [Kanzelhöhe Observatory—IGAM, Institute of Physics, University of Graz, Universittsplatz 5, A-8010 Graz (Austria); Taktakishvili, A.; Mays, M. L. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Odstrčil, D., E-mail: bvrsnak@geof.hr, E-mail: tzic@geof.hr, E-mail: mdumbovic@geof.hr, E-mail: manuela.temmer@uni-graz.at, E-mail: christian.moestl@uni-graz.at, E-mail: astrid.veronig@uni-graz.at, E-mail: aleksandre.taktakishvili-1@nasa.gov, E-mail: m.leila.mays@nasa.gov, E-mail: dusan.odstrcil@nasa.gov [George Mason University, Fairfax, VA 22030 (United States)

    2014-08-01

    Real-time forecasting of the arrival of coronal mass ejections (CMEs) at Earth, based on remote solar observations, is one of the central issues of space-weather research. In this paper, we compare arrival-time predictions calculated applying the numerical ''WSA-ENLIL+Cone model'' and the analytical ''drag-based model'' (DBM). Both models use coronagraphic observations of CMEs as input data, thus providing an early space-weather forecast two to four days before the arrival of the disturbance at the Earth, depending on the CME speed. It is shown that both methods give very similar results if the drag parameter Γ = 0.1 is used in DBM in combination with a background solar-wind speed of w = 400 km s{sup –1}. For this combination, the mean value of the difference between arrival times calculated by ENLIL and DBM is Δ-bar =0.09±9.0 hr with an average of the absolute-value differences of |Δ|-bar =7.1 hr. Comparing the observed arrivals (O) with the calculated ones (C) for ENLIL gives O – C = –0.3 ± 16.9 hr and, analogously, O – C = +1.1 ± 19.1 hr for DBM. Applying Γ = 0.2 with w = 450 km s{sup –1} in DBM, one finds O – C = –1.7 ± 18.3 hr, with an average of the absolute-value differences of 14.8 hr, which is similar to that for ENLIL, 14.1 hr. Finally, we demonstrate that the prediction accuracy significantly degrades with increasing solar activity.

  20. Modeling Multi-Level Systems

    CERN Document Server

    Iordache, Octavian

    2011-01-01

    This book is devoted to modeling of multi-level complex systems, a challenging domain for engineers, researchers and entrepreneurs, confronted with the transition from learning and adaptability to evolvability and autonomy for technologies, devices and problem solving methods. Chapter 1 introduces the multi-scale and multi-level systems and highlights their presence in different domains of science and technology. Methodologies as, random systems, non-Archimedean analysis, category theory and specific techniques as model categorification and integrative closure, are presented in chapter 2. Chapters 3 and 4 describe polystochastic models, PSM, and their developments. Categorical formulation of integrative closure offers the general PSM framework which serves as a flexible guideline for a large variety of multi-level modeling problems. Focusing on chemical engineering, pharmaceutical and environmental case studies, the chapters 5 to 8 analyze mixing, turbulent dispersion and entropy production for multi-scale sy...

  1. Brief history of agricultural systems modeling.

    Science.gov (United States)

    Jones, James W; Antle, John M; Basso, Bruno; Boote, Kenneth J; Conant, Richard T; Foster, Ian; Godfray, H Charles J; Herrero, Mario; Howitt, Richard E; Janssen, Sander; Keating, Brian A; Munoz-Carpena, Rafael; Porter, Cheryl H; Rosenzweig, Cynthia; Wheeler, Tim R

    2017-07-01

    Agricultural systems science generates knowledge that allows researchers to consider complex problems or take informed agricultural decisions. The rich history of this science exemplifies the diversity of systems and scales over which they operate and have been studied. Modeling, an essential tool in agricultural systems science, has been accomplished by scientists from a wide range of disciplines, who have contributed concepts and tools over more than six decades. As agricultural scientists now consider the "next generation" models, data, and knowledge products needed to meet the increasingly complex systems problems faced by society, it is important to take stock of this history and its lessons to ensure that we avoid re-invention and strive to consider all dimensions of associated challenges. To this end, we summarize here the history of agricultural systems modeling and identify lessons learned that can help guide the design and development of next generation of agricultural system tools and methods. A number of past events combined with overall technological progress in other fields have strongly contributed to the evolution of agricultural system modeling, including development of process-based bio-physical models of crops and livestock, statistical models based on historical observations, and economic optimization and simulation models at household and regional to global scales. Characteristics of agricultural systems models have varied widely depending on the systems involved, their scales, and the wide range of purposes that motivated their development and use by researchers in different disciplines. Recent trends in broader collaboration across institutions, across disciplines, and between the public and private sectors suggest that the stage is set for the major advances in agricultural systems science that are needed for the next generation of models, databases, knowledge products and decision support systems. The lessons from history should be

  2. The systems integration modeling system

    International Nuclear Information System (INIS)

    Danker, W.J.; Williams, J.R.

    1990-01-01

    This paper discusses the systems integration modeling system (SIMS), an analysis tool for the detailed evaluation of the structure and related performance of the Federal Waste Management System (FWMS) and its interface with waste generators. It's use for evaluations in support of system-level decisions as to FWMS configurations, the allocation, sizing, balancing and integration of functions among elements, and the establishment of system-preferred waste selection and sequencing methods and other operating strategies is presented. SIMS includes major analysis submodels which quantify the detailed characteristics of individual waste items, loaded casks and waste packages, simulate the detailed logistics of handling and processing discrete waste items and packages, and perform detailed cost evaluations

  3. Service systems concepts, modeling, and programming

    CERN Document Server

    Cardoso, Jorge; Poels, Geert

    2014-01-01

    This SpringerBrief explores the internal workings of service systems. The authors propose a lightweight semantic model for an effective representation to capture the essence of service systems. Key topics include modeling frameworks, service descriptions and linked data, creating service instances, tool support, and applications in enterprises.Previous books on service system modeling and various streams of scientific developments used an external perspective to describe how systems can be integrated. This brief introduces the concept of white-box service system modeling as an approach to mo

  4. 3D Embedded Reconfigurable SoC for Expediting Magnetometric Space Missions

    Science.gov (United States)

    Dekoulis, George

    2016-07-01

    This paper describes the development of a state-of-the-art three-dimensional embedded reconfigurable System-on-Chip (SoC) for accelerating the design of future magnetometric space missions. This involves measurements of planetary magnetic fields or measurements of heliospheric physics events' signatures superimposed on the aggregate measurements of the stronger planetary fields. The functionality of the embedded core is fully customizable, therefore, its operation is independent of the magnetic sensor being used. Standard calibration procedures still apply for setting the magnetometer measurements to the desired initial state and removing any seriatim interference inferred by the adjacent environment. The system acts as a pathfinder for future high-resolution heliospheric space missions.

  5. Stochastic Modelling of Energy Systems

    DEFF Research Database (Denmark)

    Andersen, Klaus Kaae

    2001-01-01

    is that the model structure has to be adequate for practical applications, such as system simulation, fault detection and diagnosis, and design of control strategies. This also reflects on the methods used for identification of the component models. The main result from this research is the identification......In this thesis dynamic models of typical components in Danish heating systems are considered. Emphasis is made on describing and evaluating mathematical methods for identification of such models, and on presentation of component models for practical applications. The thesis consists of seven...... research papers (case studies) together with a summary report. Each case study takes it's starting point in typical heating system components and both, the applied mathematical modelling methods and the application aspects, are considered. The summary report gives an introduction to the scope...

  6. Test-driven modeling of embedded systems

    DEFF Research Database (Denmark)

    Munck, Allan; Madsen, Jan

    2015-01-01

    To benefit maximally from model-based systems engineering (MBSE) trustworthy high quality models are required. From the software disciplines it is known that test-driven development (TDD) can significantly increase the quality of the products. Using a test-driven approach with MBSE may have...... a similar positive effect on the quality of the system models and the resulting products and may therefore be desirable. To define a test-driven model-based systems engineering (TD-MBSE) approach, we must define this approach for numerous sub disciplines such as modeling of requirements, use cases...... suggest that our method provides a sound foundation for rapid development of high quality system models....

  7. Modeling on a PWR power conversion system with system program

    International Nuclear Information System (INIS)

    Gao Rui; Yang Yanhua; Lin Meng

    2007-01-01

    Based on the power conversion system of nuclear and conventional islands of Daya Bay Power Station, this paper models the thermal-hydraulic systems of primary and secondary loops for PWR by using the PWR best-estimate program-RELAP5. To simulate the full-scope power conversion system, not only the traditional basic system models of nuclear island, but also the major system models of conventional island are all considered and modeled. A comparison between the calculated results and the actual data of reactor demonstrates a fine match for Daya Bay Nuclear Power Station, and manifests the feasibility in simulating full-scope power conversion system of PWR by RELAP5 at the same time. (authors)

  8. Formal heterogeneous system modeling with SystemC

    DEFF Research Database (Denmark)

    Niaki, Seyed Hosein Attarzadeh; Jakobsen, Mikkel Koefoed; Sulonen, Tero

    2012-01-01

    Electronic System Level (ESL) design of embedded systems proposes raising the abstraction level of the design entry to cope with the increasing complexity of such systems. To exploit the benefits of ESL, design languages should allow specification of models which are a) heterogeneous, to describe...

  9. Model Driven Development of Data Sensitive Systems

    DEFF Research Database (Denmark)

    Olsen, Petur

    2014-01-01

    storage systems, where the actual values of the data is not relevant for the behavior of the system. For many systems the values are important. For instance the control flow of the system can be dependent on the input values. We call this type of system data sensitive, as the execution is sensitive...... to the values of variables. This theses strives to improve model-driven development of such data-sensitive systems. This is done by addressing three research questions. In the first we combine state-based modeling and abstract interpretation, in order to ease modeling of data-sensitive systems, while allowing...... efficient model-checking and model-based testing. In the second we develop automatic abstraction learning used together with model learning, in order to allow fully automatic learning of data-sensitive systems to allow learning of larger systems. In the third we develop an approach for modeling and model-based...

  10. Mathematical Modeling Of Life-Support Systems

    Science.gov (United States)

    Seshan, Panchalam K.; Ganapathi, Balasubramanian; Jan, Darrell L.; Ferrall, Joseph F.; Rohatgi, Naresh K.

    1994-01-01

    Generic hierarchical model of life-support system developed to facilitate comparisons of options in design of system. Model represents combinations of interdependent subsystems supporting microbes, plants, fish, and land animals (including humans). Generic model enables rapid configuration of variety of specific life support component models for tradeoff studies culminating in single system design. Enables rapid evaluation of effects of substituting alternate technologies and even entire groups of technologies and subsystems. Used to synthesize and analyze life-support systems ranging from relatively simple, nonregenerative units like aquariums to complex closed-loop systems aboard submarines or spacecraft. Model, called Generic Modular Flow Schematic (GMFS), coded in such chemical-process-simulation languages as Aspen Plus and expressed as three-dimensional spreadsheet.

  11. The S-Web Model for the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, Spiro K.; Karpen, Judith T.; DeVore, C. Richard

    2012-01-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind has large angular width, up to 60 degrees, suggesting that its source extends far from the open-closed boundary. We describe a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices (the S-Web) and quasi-separatrix layers in the heliosphere. We discuss the dynamics of the S-Web model and its implications for present observations and for the upcoming observations from Solar Orbiter and Solar Probe Plus.

  12. Mobility Models for Systems Evaluation

    Science.gov (United States)

    Musolesi, Mirco; Mascolo, Cecilia

    Mobility models are used to simulate and evaluate the performance of mobile wireless systems and the algorithms and protocols at the basis of them. The definition of realistic mobility models is one of the most critical and, at the same time, difficult aspects of the simulation of applications and systems designed for mobile environments. There are essentially two possible types of mobility patterns that can be used to evaluate mobile network protocols and algorithms by means of simulations: traces and synthetic models [130]. Traces are obtained by means of measurements of deployed systems and usually consist of logs of connectivity or location information, whereas synthetic models are mathematical models, such as sets of equations, which try to capture the movement of the devices.

  13. A HYBRID SOLAR WIND MODEL OF THE CESE+HLL METHOD WITH A YIN-YANG OVERSET GRID AND AN AMR GRID

    International Nuclear Information System (INIS)

    Feng Xueshang; Zhang Shaohua; Xiang Changqing; Yang Liping; Jiang Chaowei; Wu, S. T.

    2011-01-01

    A hybrid three-dimensional (3D) MHD model for solar wind study is proposed in the present paper with combined grid systems and solvers. The computational domain from the Sun to Earth space is decomposed into the near-Sun and off-Sun domains, which are respectively constructed with a Yin-Yang overset grid system and a Cartesian adaptive mesh refinement (AMR) grid system and coupled with a domain connection interface in the overlapping region between the near-Sun and off-Sun domains. The space-time conservation element and solution element method is used in the near-Sun domain, while the Harten-Lax-Leer method is employed in the off-Sun domain. The Yin-Yang overset grid can avoid well-known singularity and polar grid convergence problems and its body-fitting property helps achieve high-quality resolution near the solar surface. The block structured AMR Cartesian grid can automatically capture far-field plasma flow features, such as heliospheric current sheets and shock waves, and at the same time, it can save significant computational resources compared to the uniformly structured Cartesian grid. A numerical study of the solar wind structure for Carrington rotation 2069 shows that the newly developed hybrid MHD solar wind model successfully produces many realistic features of the background solar wind, in both the solar corona and interplanetary space, by comparisons with multiple solar and interplanetary observations.

  14. Modeling and estimating system availability

    International Nuclear Information System (INIS)

    Gaver, D.P.; Chu, B.B.

    1976-11-01

    Mathematical models to infer the availability of various types of more or less complicated systems are described. The analyses presented are probabilistic in nature and consist of three parts: a presentation of various analytic models for availability; a means of deriving approximate probability limits on system availability; and a means of statistical inference of system availability from sparse data, using a jackknife procedure. Various low-order redundant systems are used as examples, but extension to more complex systems is not difficult

  15. A Model for SEP Escape

    Science.gov (United States)

    Antiochos, S. K.; Masson, S.; DeVore, C. R.

    2012-01-01

    Magnetic reconnection in the solar atmosphere is believed to be the driver of most solar explosive phenomena. Therefore, the topology of the coronal magnetic field is central to understanding the solar drivers of space weather. Of particular importance to space weather are the impulsive Solar Energetic particles that are associated with some CME/eruptive flare events. Observationally, the magnetic configuration of active regions where solar eruptions originate appears to agree with the standard eruptive flare model. According to this model, particles accelerated at the flare reconnection site should remain trapped in the corona and the ejected plasmoid. However, flare-accelerated particles frequently reach the Earth long before the CME does. We present a model that may account for the injection of energetic particles onto open magnetic flux tubes connecting to the Earth. Our model is based on the well-known 2.5D breakout topology, which has a coronal null point (null line) and a four-flux system. A key new addition, however, is that we include an isothermal solar wind with open-flux regions. Depending on the location of the open flux with respect to the null point, we find that the flare reconnection can consist of two distinct phases. At first, the flare reconnection involves only closed field, but if the eruption occurs close to the open field, we find a second phase involving interchange reconnection between open and closed. We argue that this second reconnection episode is responsible for the injection of flare-accelerated particles into the interplanetary medium. We will report on our recent work toward understanding how flare particles escape to the heliosphere. This work uses high-resolution 2.5D MHD numerical simulations performed with the Adaptively Refined MHD Solver (ARMS).

  16. Grey Box Modelling of Hydrological Systems

    DEFF Research Database (Denmark)

    Thordarson, Fannar Ørn

    of two papers where the stochastic differential equation based model is used for sewer runoff from a drainage system. A simple model is used to describe a complex rainfall-runoff process in a catchment, but the stochastic part of the system is formulated to include the increasing uncertainty when...... rainwater flows through the system, as well as describe the lower limit of the uncertainty when the flow approaches zero. The first paper demonstrates in detail the grey box model and all related transformations required to obtain a feasible model for the sewer runoff. In the last paper this model is used......The main topic of the thesis is grey box modelling of hydrologic systems, as well as formulation and assessment of their embedded uncertainties. Grey box model is a combination of a white box model, a physically-based model that is traditionally formulated using deterministic ordinary differential...

  17. Muon Excess at Sea Level during the Progress of a Geomagnetic Storm and High-Speed Stream Impact Near the Time of Earth's Heliospheric Sheet Crossing

    Science.gov (United States)

    Augusto, C. R. A.; Navia, C. E.; de Oliveira, M. N.; Nepomuceno, A. A.; Kopenkin, V.; Sinzi, T.

    2017-08-01

    In this article we present results of studying the association between the muon flux variation at ground level, registered by the New-Tupi muon telescopes (22° 53'00'' S, 43° 06'13' W; 3 m above sea level), and the geomagnetic storm on 25 - 29 August 2015 that has raged for several days as a result of a coronal mass ejection (CME) impact on Earth's magnetosphere. A sequence of events started with an M3.5 X-ray class flare on 22 August 2015 at 21:19 UTC. The New-Tupi muon telescopes observed a Forbush decrease (FD) triggered by this geomagnetic storm, which began on 26 August 2015. After Earth crossed the heliospheric current sheet (HCS), an increase in particle flux was observed on 28 August 2015 by spacecraft and ground-level detectors. The observed peak was in temporal coincidence with the impact of a high-speed stream (HSS). We study this increase, which has been observed with a significance above 1.5% by ground-level detectors in different rigidity regimes. We also estimate the lower limit of the energy fluence injected on Earth. In addition, we consider the origin of this increase, such as acceleration of particles by shock waves at the front of the HSS and the focusing effect of the HCS crossing. Our results show possible evidence of a prolonged energetic (up to GeV energies) particle injection within the Earth atmosphere system, driven by the HSS. In most cases, these injected particles are directed to the polar regions. However, the particles from the high-energy tail of the spectrum can reach mid-latitudes, and this could have consequences for the atmospheric chemistry. For instance, the creation of NOx species may be enhanced, and this can lead to increased ozone depletion. This topic requires further study.

  18. Solar magnetic field - 1976 through 1985: an atlas of photospheric magnetic field observations and computed coronal magnetic fields from the John M. Wilcox Solar Observatory at Stanford, 1976-1985

    International Nuclear Information System (INIS)

    Hoeksema, J.T.; Scherrer, P.H.

    1986-01-01

    Daily magnetogram observations of the large-scale photospheric magnetic field have been made at the John M. Wilcox Solar Observatory at Stanford since May of 1976. These measurements provide a homogeneous record of the changing solar field through most of Solar Cycle 21. Using the photospheric data, the configuration of the coronal and heliospheric fields can be calculated using a Potential Field -- Source Surface model. This provides a 3-dimensional picture of the heliospheric field-evolution during the solar cycle. In this report the authors present the complete set of synoptic charts of the measured photospheric magnetic field, the computed field at the source surface, and the coefficients of the multipole expansion of the coronal field. The general underlying structure of the solar and heliospheric fields, which determine the environment for solar - terrestrial relations and provide the context within which solar-activity-related events occur, can be approximated from these data

  19. Model systems in photosynthesis research

    International Nuclear Information System (INIS)

    Katz, J.J.; Hindman, J.C.

    1981-01-01

    After a general discussion of model studies in photosynthesis research, three recently developed model systems are described. The current status of covalently linked chlorophyll pairs as models for P700 and P865 is first briefly reviewed. Mg-tris(pyrochlorophyllide)1,1,1-tris(hydroxymethyl) ethane triester in its folded configuration is then discussed as a rudimentary antenna-photoreaction center model. Finally, self-assembled chlorophyll systems that contain a mixture of monomeric, oligomeric and special pair chlorophyll are shown to have fluorescence emission characteristics that resemble thoe of intact Tribonema aequale at room temperature in that both show fluorescence emission at 675 and 695 nm. In the self-assembled systems the wavelength of the emitted fluorescence depends on the wavelength of excitation, arguing that energy transfer between different chlorophyll species in these systems may be more complex than previously suspected

  20. [Model-based biofuels system analysis: a review].

    Science.gov (United States)

    Chang, Shiyan; Zhang, Xiliang; Zhao, Lili; Ou, Xunmin

    2011-03-01

    Model-based system analysis is an important tool for evaluating the potential and impacts of biofuels, and for drafting biofuels technology roadmaps and targets. The broad reach of the biofuels supply chain requires that biofuels system analyses span a range of disciplines, including agriculture/forestry, energy, economics, and the environment. Here we reviewed various models developed for or applied to modeling biofuels, and presented a critical analysis of Agriculture/Forestry System Models, Energy System Models, Integrated Assessment Models, Micro-level Cost, Energy and Emission Calculation Models, and Specific Macro-level Biofuel Models. We focused on the models' strengths, weaknesses, and applicability, facilitating the selection of a suitable type of model for specific issues. Such an analysis was a prerequisite for future biofuels system modeling, and represented a valuable resource for researchers and policy makers.

  1. Cross-calibration of far UV spectra of solar system objects and the heliosphere

    CERN Document Server

    Snow, Martin; Bonnet, Roger-Maurice

    2013-01-01

    This book is the result of a working group sponsored by ISSI in Bern, which was initially created to study possible ways to calibrate a Far Ultraviolet (FUV) instrument after launch. In most cases, ultraviolet instruments are well calibrated on the ground, but unfortunately, optics and detectors in the FUV are very sensitive to contaminants and it is very challenging to prevent contamination before and during the test and launch sequences of a space mission. Therefore, ground calibrations need to be confirmed after launch and it is necessary to keep track of the temporal evolution of the sensitivity of the instrument during the mission. The studies presented here cover various fields of FUV spectroscopy with the exclusion of direct solar UV spectroscopy, including a catalog of stellar spectra, data-sets of lunar Irradiance, observations of comets and measurements of the interplanetary background. Detailed modeling of the interplanetary background is presented as well. This work also includes comparisons of ol...

  2. Calibration of the kinematic method of studying solar wind disturbances on the basis of a one-dimensional MHD solution and a simulation study of the heliosphere disturbances between 22 November and 6 December 1977

    International Nuclear Information System (INIS)

    Sun, W.; Akasofu, S.-I.; Smith, Z.K.; Dryer, M.

    1985-01-01

    An empirical kinematic method developed by Hakamada and Akasofu (1982) is calibrated on the basis of a one-dimensional MHD solution. The calibrated results are used to simulate the stream-stream interaction and the background corotating structure in a simple situation and also during 22 November-6 December 1977. The solar wind disturbances caused by solar activities during this period are then introduced into the above background stream in simulating the heliospheric disturbance event which was observed by an aligned set of spacecraft at distances between 0.6 and 1.6 a.u. The observations and the simulated results are satisfactory, and a little more refinement in the simulation could reconstruct reasonably well the data by filling the data gaps in the solar wind speed, the density and the IMF magnitude. (author)

  3. Pembangunan Model Restaurant Management System

    Directory of Open Access Journals (Sweden)

    Fredy Jingga

    2014-12-01

    Full Text Available Model design for Restaurant Management System aims to help in restaurant business process, where Restaurant Management System (RMS help the waitress and chef could interact each other without paper limitation.  This Restaurant Management System Model develop using Agile Methodology and developed based on PHP Programming Langguage. The database management system is using MySQL. This web-based application model will enable the waitress and the chef to interact in realtime, from the time they accept the customer order until the chef could know what to cook and checklist for the waitress wheter the order is fullfill or not, until the cahsier that will calculate the bill and the payment that they accep from the customer.

  4. Semantic models for adaptive interactive systems

    CERN Document Server

    Hussein, Tim; Lukosch, Stephan; Ziegler, Jürgen; Calvary, Gaëlle

    2013-01-01

    Providing insights into methodologies for designing adaptive systems based on semantic data, and introducing semantic models that can be used for building interactive systems, this book showcases many of the applications made possible by the use of semantic models.Ontologies may enhance the functional coverage of an interactive system as well as its visualization and interaction capabilities in various ways. Semantic models can also contribute to bridging gaps; for example, between user models, context-aware interfaces, and model-driven UI generation. There is considerable potential for using

  5. Pressurized water reactor system model for control system design and analysis

    International Nuclear Information System (INIS)

    Cooper, K.F.; Cain, J.T.

    1975-01-01

    Satisfactory operation of present generation Pressurized Water Reactor (PWR) Nuclear Power systems requires that several independent and interactive control systems be designed. Since it is not practical to use an actual PWR system as a design tool, a mathematical model of the system must be developed as a design and analysis tool. The model presented has been developed to be used as an aid in applying optimal control theory to design and implement new control systems for PWR plants. To be applicable, the model developed must represent the PWR system in its normal operating range. For safety analysis the operating conditions of the system are usually abnormal and, therefore, the system modeling requirements are different from those for control system design and analysis

  6. System Dynamics Modeling of Multipurpose Reservoir Operation

    Directory of Open Access Journals (Sweden)

    Ebrahim Momeni

    2006-03-01

    Full Text Available System dynamics, a feedback – based object – oriented simulation approach, not only represents complex dynamic systemic systems in a realistic way but also allows the involvement of end users in model development to increase their confidence in modeling process. The increased speed of model development, the possibility of group model development, the effective communication of model results, and the trust developed in the model due to user participation are the main strengths of this approach. The ease of model modification in response to changes in the system and the ability to perform sensitivity analysis make this approach more attractive compared with systems analysis techniques for modeling water management systems. In this study, a system dynamics model was developed for the Zayandehrud basin in central Iran. This model contains river basin, dam reservoir, plains, irrigation systems, and groundwater. Current operation rule is conjunctive use of ground and surface water. Allocation factor for each irrigation system is computed based on the feedback from groundwater storage in its zone. Deficit water is extracted from groundwater.The results show that applying better rules can not only satisfy all demands such as Gawkhuni swamp environmental demand, but it can also  prevent groundwater level drawdown in future.

  7. Modeling Sustainable Food Systems.

    Science.gov (United States)

    Allen, Thomas; Prosperi, Paolo

    2016-05-01

    The processes underlying environmental, economic, and social unsustainability derive in part from the food system. Building sustainable food systems has become a predominating endeavor aiming to redirect our food systems and policies towards better-adjusted goals and improved societal welfare. Food systems are complex social-ecological systems involving multiple interactions between human and natural components. Policy needs to encourage public perception of humanity and nature as interdependent and interacting. The systemic nature of these interdependencies and interactions calls for systems approaches and integrated assessment tools. Identifying and modeling the intrinsic properties of the food system that will ensure its essential outcomes are maintained or enhanced over time and across generations, will help organizations and governmental institutions to track progress towards sustainability, and set policies that encourage positive transformations. This paper proposes a conceptual model that articulates crucial vulnerability and resilience factors to global environmental and socio-economic changes, postulating specific food and nutrition security issues as priority outcomes of food systems. By acknowledging the systemic nature of sustainability, this approach allows consideration of causal factor dynamics. In a stepwise approach, a logical application is schematized for three Mediterranean countries, namely Spain, France, and Italy.

  8. System Advisor Model: Flat Plate Photovoltaic Performance Modeling Validation Report

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, Janine [National Renewable Energy Lab. (NREL), Golden, CO (United States); Whitmore, Jonathan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kaffine, Leah [National Renewable Energy Lab. (NREL), Golden, CO (United States); Blair, Nate [National Renewable Energy Lab. (NREL), Golden, CO (United States); Dobos, Aron P. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2013-12-01

    The System Advisor Model (SAM) is a free software tool that performs detailed analysis of both system performance and system financing for a variety of renewable energy technologies. This report provides detailed validation of the SAM flat plate photovoltaic performance model by comparing SAM-modeled PV system generation data to actual measured production data for nine PV systems ranging from 75 kW to greater than 25 MW in size. The results show strong agreement between SAM predictions and field data, with annualized prediction error below 3% for all fixed tilt cases and below 8% for all one axis tracked cases. The analysis concludes that snow cover and system outages are the primary sources of disagreement, and other deviations resulting from seasonal biases in the irradiation models and one axis tracking issues are discussed in detail.

  9. On the source of the 5-55 keV Heliosphere ENAs measured with Cassini/INCA

    Science.gov (United States)

    Dialynas, Konstantinos; Roelof, Edmond; Mitchell, Donald; Krimigis, Stamatios; Decker, Robert

    2016-07-01

    The Low Energy Charged Particle (LECP) in situ measurements from V1 and V2 have revealed a reservoir of ions and electrons that constitute the heliosheath (HS) after crossing the termination shock (TS) 35deg north and 32deg south of the ecliptic plane at 94 and 84 astronomical units (1 AU= 1.5 x10 ^{8} km), respectively. The outer Heliosphere boundary, the Heliopause (HP), has now been determined in the direction of V1 to be at ˜122 AU. The in situ measurements by each Voyager were placed in a global context by remote sensing images using ENA obtained with the Ion and Neutral Camera (INCA) onboard Cassini orbiting Saturn. The ENA images have revealed a 5.2-55 keV hydrogen (H) ENA region (Belt) that loops through the celestial sphere and contributes to balancing the pressure of the interstellar magnetic field (ISMF). Here we address one of the remaining and most important questions: Where do the 5-55 keV ENAs that INCA measures come from? We analyzed INCA all-sky maps from 2003 to 2015 and compare the solar cycle (SC) variation of the ENAs in both the nose (upstream) and anti-nose (downstream) directions with the intensities of > 30 keV ions (source of ENA through charge exchange-CE with H) measured in-situ by V1 and V2, in overlapping energy bands ˜30-55 keV. ENA intensities decrease during the declining phase of SC23 by ˜x3 from 2003 to 2011 but recover through 2014 (SC24); similarly, V1 and V2 ion intensities also decrease and then recover through 2014. The similarity of time profiles of remotely sensed ENA and locally measured ions are consistent with (a) ENA originating in the HS, and (b) the global HS responding promptly (within ˜1-1.5 years) to outward-propagating solar wind changes throughout the SC. Further, recovery of the Belt during SC24 precedes asymmetrically from south to north in the general direction of the nose. This may be related to the non-symmetric evolution of solar coronal holes during SC recovery.

  10. Space physics strategy-implementation study. Volume 1: Goals, objectives, strategy. A report to the Space Physics Subcommittee of the Space Science and Applications Advisory Committee

    Science.gov (United States)

    1991-01-01

    Space physics is defined as the study of the heliosphere as one system; that is, of the Sun and solar wind, and their interactions with the upper atmospheres, ionospheres, and magnetospheres of the planets and comets, with energetic particles, and with the interstellar medium. This report contains a number of reports by different panels on the major topics in the space physics program including: (1) the cosmic and heliospheric physics program for the years 1995 to 2010; (2) ionosphere, thermosphere, and mesosphere studies; (3) magnetospheric physics; (4) solar physics; and (5) space physics theory.

  11. The UK Earth System Model project

    Science.gov (United States)

    Tang, Yongming

    2016-04-01

    In this talk we will describe the development and current status of the UK Earth System Model (UKESM). This project is a NERC/Met Office collaboration and has two objectives; to develop and apply a world-leading Earth System Model, and to grow a community of UK Earth System Model scientists. We are building numerical models that include all the key components of the global climate system, and contain the important process interactions between global biogeochemistry, atmospheric chemistry and the physical climate system. UKESM will be used to make key CMIP6 simulations as well as long-time (e.g. millennium) simulations, large ensemble experiments and investigating a range of future carbon emission scenarios.

  12. Model-based version management system framework

    International Nuclear Information System (INIS)

    Mehmood, W.

    2016-01-01

    In this paper we present a model-based version management system. Version Management System (VMS) a branch of software configuration management (SCM) aims to provide a controlling mechanism for evolution of software artifacts created during software development process. Controlling the evolution requires many activities to perform, such as, construction and creation of versions, identification of differences between versions, conflict detection and merging. Traditional VMS systems are file-based and consider software systems as a set of text files. File based VMS systems are not adequate for performing software configuration management activities such as, version control on software artifacts produced in earlier phases of the software life cycle. New challenges of model differencing, merge, and evolution control arise while using models as central artifact. The goal of this work is to present a generic framework model-based VMS which can be used to overcome the problem of tradition file-based VMS systems and provide model versioning services. (author)

  13. Modeling and simulation of systems using Matlab and Simulink

    CERN Document Server

    Chaturvedi, Devendra K

    2009-01-01

    Introduction to SystemsSystemClassification of SystemsLinear SystemsTime-Varying vs. Time-Invariant Systems Lumped vs. Distributed Parameter SystemsContinuous- and Discrete-Time Systems Deterministic vs. Stochastic Systems Hard and Soft Systems Analysis of Systems Synthesis of Systems Introduction to System Philosophy System Thinking Large and Complex Applied System Engineering: A Generic ModelingSystems ModelingIntroduction Need of System Modeling Modeling Methods for Complex Systems Classification of ModelsCharacteristics of Models ModelingMathematical Modeling of Physical SystemsFormulation of State Space Model of SystemsPhysical Systems Theory System Components and Interconnections Computation of Parameters of a Component Single Port and Multiport Systems Techniques of System Analysis Basics of Linear Graph Theoretic ApproachFormulation of System Model for Conceptual SystemFormulation System Model for Physical SystemsTopological RestrictionsDevelopment of State Model of Degenerative SystemSolution of Stat...

  14. The dependence of magnetosphere-ionosphere system on the Earth's magnetic dipole moment

    Science.gov (United States)

    Ngwira, C. M.; Pulkkinen, A. A.; Sibeck, D. G.; Rastaetter, L.

    2017-12-01

    Space weather is increasingly recognized as an international problem affecting several different man-made technologies. The ability to understand, monitor and forecast Earth-directed space weather is of paramount importance for our highly technology-dependent society and for the current rapid developments in awareness and exploration within the heliosphere. It is well known that the strength of the Earth's magnetic field changes over long time scales. We use physics-based simulations with the University of Michigan Space Weather Modeling Framework (SWMF) to examine how the magnetosphere, ionosphere, and ground geomagnetic field perturbations respond as the geomagnetic dipole moment changes. We discuss the implication of these results for our community and the end-users of space weather information.

  15. Fuzzy model-based servo and model following control for nonlinear systems.

    Science.gov (United States)

    Ohtake, Hiroshi; Tanaka, Kazuo; Wang, Hua O

    2009-12-01

    This correspondence presents servo and nonlinear model following controls for a class of nonlinear systems using the Takagi-Sugeno fuzzy model-based control approach. First, the construction method of the augmented fuzzy system for continuous-time nonlinear systems is proposed by differentiating the original nonlinear system. Second, the dynamic fuzzy servo controller and the dynamic fuzzy model following controller, which can make outputs of the nonlinear system converge to target points and to outputs of the reference system, respectively, are introduced. Finally, the servo and model following controller design conditions are given in terms of linear matrix inequalities. Design examples illustrate the utility of this approach.

  16. Distribution system modeling and analysis

    CERN Document Server

    Kersting, William H

    2001-01-01

    For decades, distribution engineers did not have the sophisticated tools developed for analyzing transmission systems-often they had only their instincts. Things have changed, and we now have computer programs that allow engineers to simulate, analyze, and optimize distribution systems. Powerful as these programs are, however, without a real understanding of the operating characteristics of a distribution system, engineers using the programs can easily make serious errors in their designs and operating procedures. Distribution System Modeling and Analysis helps prevent those errors. It gives readers a basic understanding of the modeling and operating characteristics of the major components of a distribution system. One by one, the author develops and analyzes each component as a stand-alone element, then puts them all together to analyze a distribution system comprising the various shunt and series devices for power-flow and short-circuit studies. He includes the derivation of all models and includes many num...

  17. Analysis hierarchical model for discrete event systems

    Science.gov (United States)

    Ciortea, E. M.

    2015-11-01

    The This paper presents the hierarchical model based on discrete event network for robotic systems. Based on the hierarchical approach, Petri network is analysed as a network of the highest conceptual level and the lowest level of local control. For modelling and control of complex robotic systems using extended Petri nets. Such a system is structured, controlled and analysed in this paper by using Visual Object Net ++ package that is relatively simple and easy to use, and the results are shown as representations easy to interpret. The hierarchical structure of the robotic system is implemented on computers analysed using specialized programs. Implementation of hierarchical model discrete event systems, as a real-time operating system on a computer network connected via a serial bus is possible, where each computer is dedicated to local and Petri model of a subsystem global robotic system. Since Petri models are simplified to apply general computers, analysis, modelling, complex manufacturing systems control can be achieved using Petri nets. Discrete event systems is a pragmatic tool for modelling industrial systems. For system modelling using Petri nets because we have our system where discrete event. To highlight the auxiliary time Petri model using transport stream divided into hierarchical levels and sections are analysed successively. Proposed robotic system simulation using timed Petri, offers the opportunity to view the robotic time. Application of goods or robotic and transmission times obtained by measuring spot is obtained graphics showing the average time for transport activity, using the parameters sets of finished products. individually.

  18. Human performance modeling for system of systems analytics :soldier fatigue.

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, Craig R.; Campbell, James E.; Miller, Dwight Peter

    2005-10-01

    The military has identified Human Performance Modeling (HPM) as a significant requirement and challenge of future systems modeling and analysis initiatives as can be seen in the Department of Defense's (DoD) Defense Modeling and Simulation Office's (DMSO) Master Plan (DoD 5000.59-P 1995). To this goal, the military is currently spending millions of dollars on programs devoted to HPM in various military contexts. Examples include the Human Performance Modeling Integration (HPMI) program within the Air Force Research Laboratory, which focuses on integrating HPMs with constructive models of systems (e.g. cockpit simulations) and the Navy's Human Performance Center (HPC) established in September 2003. Nearly all of these initiatives focus on the interface between humans and a single system. This is insufficient in the era of highly complex network centric SoS. This report presents research and development in the area of HPM in a system-of-systems (SoS). Specifically, this report addresses modeling soldier fatigue and the potential impacts soldier fatigue can have on SoS performance.

  19. Anomalous Transport of Cosmic Rays in a Nonlinear Diffusion Model

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, Yuri E. [Department of Mathematics, University of Waikato, P. B. 3105, Hamilton 3240 (New Zealand); Fichtner, Horst; Walter, Dominik [Institut für Theoretische Physik IV, Ruhr-Universität Bochum, Universitätsstrasse 150, D-44780 Bochum (Germany)

    2017-05-20

    We investigate analytically and numerically the transport of cosmic rays following their escape from a shock or another localized acceleration site. Observed cosmic-ray distributions in the vicinity of heliospheric and astrophysical shocks imply that anomalous, superdiffusive transport plays a role in the evolution of the energetic particles. Several authors have quantitatively described the anomalous diffusion scalings, implied by the data, by solutions of a formal transport equation with fractional derivatives. Yet the physical basis of the fractional diffusion model remains uncertain. We explore an alternative model of the cosmic-ray transport: a nonlinear diffusion equation that follows from a self-consistent treatment of the resonantly interacting cosmic-ray particles and their self-generated turbulence. The nonlinear model naturally leads to superdiffusive scalings. In the presence of convection, the model yields a power-law dependence of the particle density on the distance upstream of the shock. Although the results do not refute the use of a fractional advection–diffusion equation, they indicate a viable alternative to explain the anomalous diffusion scalings of cosmic-ray particles.

  20. Dynamic Model of Kaplan Turbine Regulating System Suitable for Power System Analysis

    OpenAIRE

    Zhao, Jie; Wang, Li; Liu, Dichen; Wang, Jun; Zhao, Yu; Liu, Tian; Wang, Haoyu

    2015-01-01

    Accurate modeling of Kaplan turbine regulating system is of great significance for grid security and stability analysis. In this paper, Kaplan turbine regulating system model is divided into the governor system model, the blade control system model, and the turbine and water diversion system model. The Kaplan turbine has its particularity, and the on-cam relationship between the wicket gate opening and the runner blade angle under a certain water head on the whole range was obtained by high-o...

  1. System Dynamics Modeling for Emergency Operating System Resilience

    Energy Technology Data Exchange (ETDEWEB)

    Eng, Ang Wei; Kim, Jong Hyun [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2014-10-15

    The purpose of this paper is to present a causal model which explain human error cause-effect relationships of emergency operating system (EOS) by using system dynamics (SD) approach. The causal model will further quantified by analyzes nuclear power plant incidents/accidents data in Korea for simulation modeling. Emergency Operating System (EOS) is generally defined as a system which consists personnel, human-machine interface and procedures; and how these components interact and coordinate to respond to an incident or accident. Understanding the behavior of EOS especially personnel behavior and the factors influencing it during accident will contribute in human reliability evaluation. Human Reliability Analysis (HRA) is a method which assesses how human decisions and actions affect to system risk and further used to reduce the human errors probability. There are many HRA method used performance influencing factors (PIFs) to identify the causes of human errors. However, these methods have several limitations. In HRA, PIFs are assumed independent each other and relationship between them are not been study. Through the SD simulation, users able to simulate various situation of nuclear power plant respond to emergency from human and organizational aspects. The simulation also provides users a comprehensive view on how to improve the safety in plants. This paper presents a causal model that explained cause-effect relationships of EOS human. Through SD simulation, users able to identify the main contribution of human error easily. Users can also use SD simulation to predict when and how a human error occurs over time. In future work, the SD model can be expanded more on low level factors. The relationship within low level factors can investigated by using correlation method and further included in the model. This can enables users to study more detailed human error cause-effect relationships and the behavior of EOS. Another improvement can be made is on EOS factors

  2. System Dynamics Modeling for Emergency Operating System Resilience

    International Nuclear Information System (INIS)

    Eng, Ang Wei; Kim, Jong Hyun

    2014-01-01

    The purpose of this paper is to present a causal model which explain human error cause-effect relationships of emergency operating system (EOS) by using system dynamics (SD) approach. The causal model will further quantified by analyzes nuclear power plant incidents/accidents data in Korea for simulation modeling. Emergency Operating System (EOS) is generally defined as a system which consists personnel, human-machine interface and procedures; and how these components interact and coordinate to respond to an incident or accident. Understanding the behavior of EOS especially personnel behavior and the factors influencing it during accident will contribute in human reliability evaluation. Human Reliability Analysis (HRA) is a method which assesses how human decisions and actions affect to system risk and further used to reduce the human errors probability. There are many HRA method used performance influencing factors (PIFs) to identify the causes of human errors. However, these methods have several limitations. In HRA, PIFs are assumed independent each other and relationship between them are not been study. Through the SD simulation, users able to simulate various situation of nuclear power plant respond to emergency from human and organizational aspects. The simulation also provides users a comprehensive view on how to improve the safety in plants. This paper presents a causal model that explained cause-effect relationships of EOS human. Through SD simulation, users able to identify the main contribution of human error easily. Users can also use SD simulation to predict when and how a human error occurs over time. In future work, the SD model can be expanded more on low level factors. The relationship within low level factors can investigated by using correlation method and further included in the model. This can enables users to study more detailed human error cause-effect relationships and the behavior of EOS. Another improvement can be made is on EOS factors

  3. Mathematical Modeling of Constrained Hamiltonian Systems

    NARCIS (Netherlands)

    Schaft, A.J. van der; Maschke, B.M.

    1995-01-01

    Network modelling of unconstrained energy conserving physical systems leads to an intrinsic generalized Hamiltonian formulation of the dynamics. Constrained energy conserving physical systems are directly modelled as implicit Hamiltonian systems with regard to a generalized Dirac structure on the

  4. A model management system for combat simulation

    OpenAIRE

    Dolk, Daniel R.

    1986-01-01

    The design and implementation of a model management system to support combat modeling is discussed. Structured modeling is introduced as a formalism for representing mathematical models. A relational information resource dictionary system is developed which can accommodate structured models. An implementation is described. Structured modeling is then compared to Jackson System Development (JSD) as a methodology for facilitating discrete event simulation. JSD is currently better at representin...

  5. Dynamic Model of Kaplan Turbine Regulating System Suitable for Power System Analysis

    Directory of Open Access Journals (Sweden)

    Jie Zhao

    2015-01-01

    Full Text Available Accurate modeling of Kaplan turbine regulating system is of great significance for grid security and stability analysis. In this paper, Kaplan turbine regulating system model is divided into the governor system model, the blade control system model, and the turbine and water diversion system model. The Kaplan turbine has its particularity, and the on-cam relationship between the wicket gate opening and the runner blade angle under a certain water head on the whole range was obtained by high-order curve fitting method. Progressively the linearized Kaplan turbine model, improved ideal Kaplan turbine model, and nonlinear Kaplan turbine model were developed. The nonlinear Kaplan turbine model considered the correction function of the blade angle on the turbine power, thereby improving the model simulation accuracy. The model parameters were calculated or obtained by the improved particle swarm optimization (IPSO algorithm. For the blade control system model, the default blade servomotor time constant given by value of one simplified the modeling and experimental work. Further studies combined with measured test data verified the established model accuracy and laid a foundation for further research into the influence of Kaplan turbine connecting to the grid.

  6. A Model-Driven Visualization Tool for Use with Model-Based Systems Engineering Projects

    Science.gov (United States)

    Trase, Kathryn; Fink, Eric

    2014-01-01

    Model-Based Systems Engineering (MBSE) promotes increased consistency between a system's design and its design documentation through the use of an object-oriented system model. The creation of this system model facilitates data presentation by providing a mechanism from which information can be extracted by automated manipulation of model content. Existing MBSE tools enable model creation, but are often too complex for the unfamiliar model viewer to easily use. These tools do not yet provide many opportunities for easing into the development and use of a system model when system design documentation already exists. This study creates a Systems Modeling Language (SysML) Document Traceability Framework (SDTF) for integrating design documentation with a system model, and develops an Interactive Visualization Engine for SysML Tools (InVEST), that exports consistent, clear, and concise views of SysML model data. These exported views are each meaningful to a variety of project stakeholders with differing subjects of concern and depth of technical involvement. InVEST allows a model user to generate multiple views and reports from a MBSE model, including wiki pages and interactive visualizations of data. System data can also be filtered to present only the information relevant to the particular stakeholder, resulting in a view that is both consistent with the larger system model and other model views. Viewing the relationships between system artifacts and documentation, and filtering through data to see specialized views improves the value of the system as a whole, as data becomes information

  7. Cyber Physical System Modelling of Distribution Power Systems for Dynamic Demand Response

    Science.gov (United States)

    Chu, Xiaodong; Zhang, Rongxiang; Tang, Maosen; Huang, Haoyi; Zhang, Lei

    2018-01-01

    Dynamic demand response (DDR) is a package of control methods to enhance power system security. A CPS modelling and simulation platform for DDR in distribution power systems is presented in this paper. CPS modelling requirements of distribution power systems are analyzed. A coupled CPS modelling platform is built for assessing DDR in the distribution power system, which combines seamlessly modelling tools of physical power networks and cyber communication networks. Simulations results of IEEE 13-node test system demonstrate the effectiveness of the modelling and simulation platform.

  8. ECONOMIC MODELING STOCKS CONTROL SYSTEM: SIMULATION MODEL

    OpenAIRE

    Климак, М.С.; Войтко, С.В.

    2016-01-01

    Considered theoretical and applied aspects of the development of simulation models to predictthe optimal development and production systems that create tangible products andservices. It isproved that theprocessof inventory control needs of economicandmathematical modeling in viewof thecomplexity of theoretical studies. A simulation model of stocks control that allows make managementdecisions with production logistics

  9. A NUMERICAL SIMULATION OF COSMIC RAY MODULATION NEAR THE HELIOPAUSE. II. SOME PHYSICAL INSIGHTS

    International Nuclear Information System (INIS)

    Luo, Xi; Feng, Xueshang; Potgieter, Marius S.; Du Toit Strauss, R.; Zhang, Ming; Pogorelov, Nikolai V.

    2016-01-01

    Cosmic ray (CR) transport near the heliopause (HP) is studied using a hybrid transport model, with the parameters constrained by observations from the Voyager 1 spacecraft. We simulate the CR radial flux along different directions in the heliosphere. There is no well-defined thin layer between the solar wind region and the interstellar region along the tail and polar directions of the heliosphere. By analyzing the radial flux curve along the direction of Voyager 2 , together with its trajectory information, the crossing time of the HP by Voyager 2 is predicted to be in 2017.14. We simulate the CR radial flux for different energy values along the direction of Voyager 1 . We find that there is only a modest modulation region of about 10 au wide beyond the HP, so that Voyager 1 observing the Local Interstellar Spectra is justified in numerical modeling. We analyze the heliospheric exit information of pseudo-particles in our stochastic numerical (time-backward) method, conjecturing that they represent the behavior of CR particles, and we find that pseudo-particles that have been traced from the nose region exit in the tail region. This implies that many CR particles diffuse directly from the heliospheric tail region to the nose region near the HP. In addition, when pseudo-particles were traced from the Local Interstellar Medium (LISM), it is found that their exit location (entrance for real particles) from the simulation domain is along the prescribed Interstellar Magnetic Field direction. This indicates that parallel diffusion dominates CR particle transport in the LISM.

  10. Simultaneous Modeling of Gradual SEP Events at the Earth and the Mars

    Science.gov (United States)

    Hu, J.; Li, G.

    2017-12-01

    Solar Energetic Particles (SEP) event is the number one space hazard for spacecraft instruments and astronauts' safety. Recent studies have shown that both longitudinal and radial extent of SEP events can be very significant. In this work, we use the improved Particle Acceleration and Transport in the Heliosphere (iPATH) model to simulate gradual SEP events that have impacts upon both the Earth and the Mars. We follow the propagation of a 2D CME-driven shock. Particles are accelerated at the shock via the diffusive shock acceleration (DSA) mechanism. Transport of the escaped particles to the Earth and the Mars is then followed using a backward stochastic differential equation method. Perpendicular diffusion is considered in both the DSA and the transport process. Model results such as time intensity profile and energetic particle spectrum at the two locations are compared to understand the spatial extent of an SEP event. Observational data at the Earth and the Mars are also studied to validate the model.

  11. 2-D Modelling of Long Period Variations of Galactic Cosmic Ray Intensity

    International Nuclear Information System (INIS)

    Siluszyk, M; Iskra, K; Alania, M

    2015-01-01

    A new two-dimensional (2-D) time dependent model describing long-period variations of the Galactic Cosmic Ray (GCR) intensity has been developed. New approximations for the changes of the magnitude B of the Interplanetary Magnetic Field (IMF), the tilt angle δ of the Heliospheric Neutral Sheet (HNS) and drift effects of the GCR particles have been included into the model. Moreover, temporal changes of the exponent γ expressing the power law - rigidity dependence of the amplitudes of the 11-year variation of the GCR intensity have been added. We show that changes of the expected GCR particle density precedes changes of the GCR intensity measured by the Moscow Neutron (MN) monitor by about 18 months. So ∼18 months can be taken as an effective delay time between the expected intensity caused by the combined influence of the changes of the parameters implemented in the time-dependent 2-D model and the GCR intensity measured by neutron monitors during the 21 cycle of solar activity. (paper)

  12. Modeling Control Situations in Power System Operations

    DEFF Research Database (Denmark)

    Saleem, Arshad; Lind, Morten; Singh, Sri Niwas

    2010-01-01

    for intelligent operation and control must represent system features, so that information from measurements can be related to possible system states and to control actions. These general modeling requirements are well understood, but it is, in general, difficult to translate them into a model because of the lack...... of explicit principles for model construction. This paper presents a work on using explicit means-ends model based reasoning about complex control situations which results in maintaining consistent perspectives and selecting appropriate control action for goal driven agents. An example of power system......Increased interconnection and loading of the power system along with deregulation has brought new challenges for electric power system operation, control and automation. Traditional power system models used in intelligent operation and control are highly dependent on the task purpose. Thus, a model...

  13. ELECTRON THERMAL CONDUCTION AS A POSSIBLE PHYSICAL MECHANISM TO MAKE THE INNER HELIOSHEATH THINNER

    International Nuclear Information System (INIS)

    Izmodenov, V. V.; Alexashov, D. B.; Ruderman, M. S.

    2014-01-01

    We show that electron thermal conductivity may strongly affect the heliosheath plasma flow and the global pattern of the solar wind's interaction with the local interstellar medium. In particular, it leads to strong reduction of the inner heliosheath thickness, which makes it possible to explain (qualitatively) why Voyager 1 (V1) has crossed the heliopause at an unexpectedly small heliocentric distance of 122 AU. To estimate the effect of thermal conductivity, we consider a limiting case when thermal conduction is very effective. To do that, we assume the plasma flow in the entire heliosphere is nearly isothermal. Due to this effect, the heliospheric distance of the termination shock has increased by about 15 AU in the V1 direction compared with the adiabatic case with γ = 5/3. The heliospheric distance of the heliopause has decreased by about 27 AU. As a result, the thickness of the inner heliosheath in the model has decreased by about 42 AU and has become equal to 32 AU

  14. On Verification Modelling of Embedded Systems

    NARCIS (Netherlands)

    Brinksma, Hendrik; Mader, Angelika H.

    Computer-aided verification of embedded systems hinges on the availability of good verification models of the systems at hand. Such models must be much simpler than full design models or specifications to be of practical value, because of the unavoidable combinatorial complexities in the

  15. Modeling and analysis of stochastic systems

    CERN Document Server

    Kulkarni, Vidyadhar G

    2011-01-01

    Based on the author's more than 25 years of teaching experience, Modeling and Analysis of Stochastic Systems, Second Edition covers the most important classes of stochastic processes used in the modeling of diverse systems, from supply chains and inventory systems to genetics and biological systems. For each class of stochastic process, the text includes its definition, characterization, applications, transient and limiting behavior, first passage times, and cost/reward models. Along with reorganizing the material, this edition revises and adds new exercises and examples. New to the second edi

  16. Modelling of Context: Designing Mobile Systems from Domain-Dependent Models

    DEFF Research Database (Denmark)

    Nielsen, Peter Axel; Stage, Jan

    2009-01-01

    Modelling of domain-dependent aspects is a key prerequisite for the design of software for mobile systems. Most mobile systems include a more or less advanced model of selected aspects of the domain in which they are used. This paper discusses the creation of such a model and its relevance for te...

  17. Model Reduction of Fuzzy Logic Systems

    Directory of Open Access Journals (Sweden)

    Zhandong Yu

    2014-01-01

    Full Text Available This paper deals with the problem of ℒ2-ℒ∞ model reduction for continuous-time nonlinear uncertain systems. The approach of the construction of a reduced-order model is presented for high-order nonlinear uncertain systems described by the T-S fuzzy systems, which not only approximates the original high-order system well with an ℒ2-ℒ∞ error performance level γ but also translates it into a linear lower-dimensional system. Then, the model approximation is converted into a convex optimization problem by using a linearization procedure. Finally, a numerical example is presented to show the effectiveness of the proposed method.

  18. Distinguishing Environment and System in Coloured Petri Net Models of Reactive Systems

    DEFF Research Database (Denmark)

    Tjell, Simon

    2007-01-01

    This paper introduces and formally defines the environment-and-system-partitioned property for behavioral models of reactive systems expressed in the formal modeling language Coloured Petri Net. The purpose of the formalization is to make it possible to automatically validate any CPN model...... with respect to this property based on structural analysis. A model has the environment-and-system-partitioned property if it is based on a clear division between environment and system. This division is important in many model-driven approaches to software development such as model-based testing and automated...

  19. Modeling the Dynamic Digestive System Microbiome†

    OpenAIRE

    Estes, Anne M.

    2015-01-01

    Modeling the Dynamic Digestive System Microbiome” is a hands-on activity designed to demonstrate the dynamics of microbiome ecology using dried pasta and beans to model disturbance events in the human digestive system microbiome. This exercise demonstrates how microbiome diversity is influenced by: 1) niche availability and habitat space and 2) a major disturbance event, such as antibiotic use. Students use a pictorial key to examine prepared models of digestive system microbiomes to determi...

  20. Modeling of the DZero data acquisition system

    Energy Technology Data Exchange (ETDEWEB)

    Angstadt, R.; Johnson, M.; Manning, I.L. [Fermi National Accelerator Lab., Batavia, IL (United States); Wightman, J.A. [Texas A and M Univ., College Station, TX (United States). Dept. of Physics]|[Texas Accelerator Center, The Woodlands, TX (United States)

    1991-12-01

    A queuing theory model was used in the initial design of the D0 data acquisition system. It was mainly used for the front end electronic systems. Since then the model has been extended to include the entire data path for the tracking system. The tracking system generates the most data so we expect this system to determine the overall transfer rate. The model was developed using both analytical and simulation methods for solving a series of single server queues. We describe the model and the methods used to develop it. We also present results from the original models, updated calculations representing the system as built and comparisons with measurements made with the hardware in place for the cosmic ray test run. 3 refs.

  1. Coupling population dynamics with earth system models: the POPEM model.

    Science.gov (United States)

    Navarro, Andrés; Moreno, Raúl; Jiménez-Alcázar, Alfonso; Tapiador, Francisco J

    2017-09-16

    Precise modeling of CO 2 emissions is important for environmental research. This paper presents a new model of human population dynamics that can be embedded into ESMs (Earth System Models) to improve climate modeling. Through a system dynamics approach, we develop a cohort-component model that successfully simulates historical population dynamics with fine spatial resolution (about 1°×1°). The population projections are used to improve the estimates of CO 2 emissions, thus transcending the bulk approach of existing models and allowing more realistic non-linear effects to feature in the simulations. The module, dubbed POPEM (from Population Parameterization for Earth Models), is compared with current emission inventories and validated against UN aggregated data. Finally, it is shown that the module can be used to advance toward fully coupling the social and natural components of the Earth system, an emerging research path for environmental science and pollution research.

  2. Modeling, Control and Coordination of Helicopter Systems

    CERN Document Server

    Ren, Beibei; Chen, Chang; Fua, Cheng-Heng; Lee, Tong Heng

    2012-01-01

    Modeling, Control and Coordination of Helicopter Systems provides a comprehensive treatment of helicopter systems, ranging from related nonlinear flight dynamic modeling and stability analysis to advanced control design for single helicopter systems, and also covers issues related to the coordination and formation control of multiple helicopter systems to achieve high performance tasks. Ensuring stability in helicopter flight is a challenging problem for nonlinear control design and development. This book is a valuable reference on modeling, control and coordination of helicopter systems,providing readers with practical solutions for the problems that still plague helicopter system design and implementation. Readers will gain a complete picture of helicopters at the systems level, as well as a better understanding of the technical intricacies involved. This book also: Presents a complete picture of modeling, control and coordination for helicopter systems Provides a modeling platform for a general class of ro...

  3. Identifying and Quantifying Emergent Behavior Through System of Systems Modeling and Simulation

    Science.gov (United States)

    2015-09-01

    the similarities and differences between Agent Based Modeling ( ABM ) and Equation Based Modeling (EBM). Both modeling approaches “simulate a system by...entities. For the latter difference, EBM focuses on the system level observables, while ABM defines behaviors at the individual agent level and observes...EMERGENT BEHAVIOR THROUGH SYSTEM OF SYSTEMS MODELING AND SIMULATION by Mary Ann Cummings September 2015 Dissertation Supervisor: Man-Tak Shing

  4. Bond graph modeling of centrifugal compression systems

    OpenAIRE

    Uddin, Nur; Gravdahl, Jan Tommy

    2015-01-01

    A novel approach to model unsteady fluid dynamics in a compressor network by using a bond graph is presented. The model is intended in particular for compressor control system development. First, we develop a bond graph model of a single compression system. Bond graph modeling offers a different perspective to previous work by modeling the compression system based on energy flow instead of fluid dynamics. Analyzing the bond graph model explains the energy flow during compressor surge. Two pri...

  5. Analytical solutions of a fractional diffusion-advection equation for solar cosmic-ray transport

    International Nuclear Information System (INIS)

    Litvinenko, Yuri E.; Effenberger, Frederic

    2014-01-01

    Motivated by recent applications of superdiffusive transport models to shock-accelerated particle distributions in the heliosphere, we analytically solve a one-dimensional fractional diffusion-advection equation for the particle density. We derive an exact Fourier transform solution, simplify it in a weak diffusion approximation, and compare the new solution with previously available analytical results and with a semi-numerical solution based on a Fourier series expansion. We apply the results to the problem of describing the transport of energetic particles, accelerated at a traveling heliospheric shock. Our analysis shows that significant errors may result from assuming an infinite initial distance between the shock and the observer. We argue that the shock travel time should be a parameter of a realistic superdiffusive transport model.

  6. Anisotropies in TeV Cosmic Rays Related to the Local Interstellar Magnetic Field from the IBEX Ribbon

    International Nuclear Information System (INIS)

    Schwadron, N A; Moebius, E; Adams, F C; Christian, E; Desiati, P; Frisch, P; Funsten, H O; Jokipii, J R; McComas, D J; Zank, G P

    2015-01-01

    The Interstellar Boundary Explorer (IBEX) observes enhanced Energetic Neutral Atoms (ENAs) emission in the keV energy range from a narrow (∼20° wide) ''ribbon'' in the sky that appears to be centered on the direction of the local interstellar (LIS) magnetic field. The Milagro collaboration, the Asγ collaboration and the IceCube observatory have recently made global maps of cosmic ray fluxes in the TeV energy range, revealing anisotropic structures ordered in part by the local interstellar magnetic field and the interstellar flow. This paper following from a recent publication in Science makes the link between these disparate observations by developing a simple model of the magnetic structure surrounding the heliosphere in the Local Interstellar Medium (LISM) that is consistent with both IBEX ENA fluxes and TeV cosmic ray anisotropies. The model also employs the revised velocity direction of the LIC derived from neutral He observations by IBEX. By modeling the propagation of cosmic rays through this magnetic field structure, we specifically show that (1) the large-scale TeV anisotropy provides a roughly consistent orientation for the local interstellar magnetic field at the center of the IBEX Ribbon and corroborates the ∼ 3 μG magnitude of the local interstellar magnetic field derived from IBEX observations of the global heliosphere; (2) and small-scale structures in cosmic rays (over < 30° angular scales) are influenced by the interstellar field interaction with the heliosphere at energies < 10 TeV. Thus, we provide a link between IBEX ENA observations, IBEX neutral observations of interstellar He, and TeV cosmic ray anisotropies, which are strongly influenced by the interactions between the local interstellar magnetic field, the flow of the local interstellar plasma, and the global heliosphere

  7. Development and Transition of the Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) Toolset

    Science.gov (United States)

    Spann, James F.; Zank, G.

    2014-01-01

    We outline a plan to develop and transition a physics based predictive toolset called The Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) to describe the interplanetary energetic particle and radiation environment throughout the inner heliosphere, including at the Earth. To forecast and "nowcast" the radiation environment requires the fusing of three components: 1) the ability to provide probabilities for incipient solar activity; 2) the use of these probabilities and daily coronal and solar wind observations to model the 3D spatial and temporal heliosphere, including magnetic field structure and transients, within 10 Astronomical Units; and 3) the ability to model the acceleration and transport of energetic particles based on current and anticipated coronal and heliospheric conditions. We describe how to address 1) - 3) based on our existing, well developed, and validated codes and models. The goal of RISCS toolset is to provide an operational forecast and "nowcast" capability that will a) predict solar energetic particle (SEP) intensities; b) spectra for protons and heavy ions; c) predict maximum energies and their duration; d) SEP composition; e) cosmic ray intensities, and f) plasma parameters, including shock arrival times, strength and obliquity at any given heliospheric location and time. The toolset would have a 72 hour predicative capability, with associated probabilistic bounds, that would be updated hourly thereafter to improve the predicted event(s) and reduce the associated probability bounds. The RISCS toolset would be highly adaptable and portable, capable of running on a variety of platforms to accommodate various operational needs and requirements. The described transition plan is based on a well established approach developed in the Earth Science discipline that ensures that the customer has a tool that meets their needs

  8. A system-level multiprocessor system-on-chip modeling framework

    DEFF Research Database (Denmark)

    Virk, Kashif Munir; Madsen, Jan

    2004-01-01

    We present a system-level modeling framework to model system-on-chips (SoC) consisting of heterogeneous multiprocessors and network-on-chip communication structures in order to enable the developers of today's SoC designs to take advantage of the flexibility and scalability of network-on-chip and...... SoC design. We show how a hand-held multimedia terminal, consisting of JPEG, MP3 and GSM applications, can be modeled as a multiprocessor SoC in our framework....

  9. Investigating immune system aging: system dynamics and agent-based modeling

    OpenAIRE

    Figueredo, Grazziela; Aickelin, Uwe

    2010-01-01

    System dynamics and agent based simulation models can\\ud both be used to model and understand interactions of entities within a population. Our modeling work presented here is concerned with understanding the suitability of the different types of simulation for the immune system aging problems and comparing their results. We are trying to answer questions such as: How fit is the immune system given a certain age? Would an immune boost be of therapeutic value, e.g. to improve the effectiveness...

  10. Compositional Modelling of Stochastic Hybrid Systems

    NARCIS (Netherlands)

    Strubbe, S.N.

    2005-01-01

    In this thesis we present a modelling framework for compositional modelling of stochastic hybrid systems. Hybrid systems consist of a combination of continuous and discrete dynamics. The state space of a hybrid system is hybrid in the sense that it consists of a continuous component and a discrete

  11. System Identification, Environmental Modelling, and Control System Design

    CERN Document Server

    Garnier, Hugues

    2012-01-01

    System Identification, Environmetric Modelling, and Control Systems Design is dedicated to Professor Peter Young on the occasion of his seventieth birthday. Professor Young has been a pioneer in systems and control, and over the past 45 years he has influenced many developments in this field. This volume is comprised of a collection of contributions by leading experts in system identification, time-series analysis, environmetric modelling and control system design – modern research in topics that reflect important areas of interest in Professor Young’s research career. Recent theoretical developments in and relevant applications of these areas are explored treating the various subjects broadly and in depth. The authoritative and up-to-date research presented here will be of interest to academic researcher in control and disciplines related to environmental research, particularly those to with water systems. The tutorial style in which many of the contributions are composed also makes the book suitable as ...

  12. CTBT Integrated Verification System Evaluation Model

    Energy Technology Data Exchange (ETDEWEB)

    Edenburn, M.W.; Bunting, M.L.; Payne, A.C. Jr.

    1997-10-01

    Sandia National Laboratories has developed a computer based model called IVSEM (Integrated Verification System Evaluation Model) to estimate the performance of a nuclear detonation monitoring system. The IVSEM project was initiated in June 1994, by Sandia`s Monitoring Systems and Technology Center and has been funded by the US Department of Energy`s Office of Nonproliferation and National Security (DOE/NN). IVSEM is a simple, top-level, modeling tool which estimates the performance of a Comprehensive Nuclear Test Ban Treaty (CTBT) monitoring system and can help explore the impact of various sensor system concepts and technology advancements on CTBT monitoring. One of IVSEM`s unique features is that it integrates results from the various CTBT sensor technologies (seismic, infrasound, radionuclide, and hydroacoustic) and allows the user to investigate synergy among the technologies. Specifically, IVSEM estimates the detection effectiveness (probability of detection) and location accuracy of the integrated system and of each technology subsystem individually. The model attempts to accurately estimate the monitoring system`s performance at medium interfaces (air-land, air-water) and for some evasive testing methods such as seismic decoupling. This report describes version 1.2 of IVSEM.

  13. Integrating systems biology models and biomedical ontologies.

    Science.gov (United States)

    Hoehndorf, Robert; Dumontier, Michel; Gennari, John H; Wimalaratne, Sarala; de Bono, Bernard; Cook, Daniel L; Gkoutos, Georgios V

    2011-08-11

    Systems biology is an approach to biology that emphasizes the structure and dynamic behavior of biological systems and the interactions that occur within them. To succeed, systems biology crucially depends on the accessibility and integration of data across domains and levels of granularity. Biomedical ontologies were developed to facilitate such an integration of data and are often used to annotate biosimulation models in systems biology. We provide a framework to integrate representations of in silico systems biology with those of in vivo biology as described by biomedical ontologies and demonstrate this framework using the Systems Biology Markup Language. We developed the SBML Harvester software that automatically converts annotated SBML models into OWL and we apply our software to those biosimulation models that are contained in the BioModels Database. We utilize the resulting knowledge base for complex biological queries that can bridge levels of granularity, verify models based on the biological phenomenon they represent and provide a means to establish a basic qualitative layer on which to express the semantics of biosimulation models. We establish an information flow between biomedical ontologies and biosimulation models and we demonstrate that the integration of annotated biosimulation models and biomedical ontologies enables the verification of models as well as expressive queries. Establishing a bi-directional information flow between systems biology and biomedical ontologies has the potential to enable large-scale analyses of biological systems that span levels of granularity from molecules to organisms.

  14. Mechatronic Systems Design Methods, Models, Concepts

    CERN Document Server

    Janschek, Klaus

    2012-01-01

    In this textbook, fundamental methods for model-based design of mechatronic systems are presented in a systematic, comprehensive form. The method framework presented here comprises domain-neutral methods for modeling and performance analysis: multi-domain modeling (energy/port/signal-based), simulation (ODE/DAE/hybrid systems), robust control methods, stochastic dynamic analysis, and quantitative evaluation of designs using system budgets. The model framework is composed of analytical dynamic models for important physical and technical domains of realization of mechatronic functions, such as multibody dynamics, digital information processing and electromechanical transducers. Building on the modeling concept of a technology-independent generic mechatronic transducer, concrete formulations for electrostatic, piezoelectric, electromagnetic, and electrodynamic transducers are presented. More than 50 fully worked out design examples clearly illustrate these methods and concepts and enable independent study of th...

  15. A strategic review of electricity systems models

    International Nuclear Information System (INIS)

    Foley, A.M.; O Gallachoir, B.P.; McKeogh, E.J.; Hur, J.; Baldick, R.

    2010-01-01

    Electricity systems models are software tools used to manage electricity demand and the electricity systems, to trade electricity and for generation expansion planning purposes. Various portfolios and scenarios are modelled in order to compare the effects of decision making in policy and on business development plans in electricity systems so as to best advise governments and industry on the least cost economic and environmental approach to electricity supply, while maintaining a secure supply of sufficient quality electricity. The modelling techniques developed to study vertically integrated state monopolies are now applied in liberalised markets where the issues and constraints are more complex. This paper reviews the changing role of electricity systems modelling in a strategic manner, focussing on the modelling response to key developments, the move away from monopoly towards liberalised market regimes and the increasing complexity brought about by policy targets for renewable energy and emissions. The paper provides an overview of electricity systems modelling techniques, discusses a number of key proprietary electricity systems models used in the USA and Europe and provides an information resource to the electricity analyst not currently readily available in the literature on the choice of model to investigate different aspects of the electricity system. (author)

  16. NEW Fe IX LINE IDENTIFICATIONS USING SOLAR AND HELIOSPHERIC OBSERVATORY/SOLAR ULTRAVIOLET MEASUREMENT OF EMITTED RADIATION AND HINODE/EIS JOINT OBSERVATIONS OF THE QUIET SUN

    International Nuclear Information System (INIS)

    Landi, E.; Young, P. R.

    2009-01-01

    In this work, we study joint observations of Hinode/EUV Imaging Spectrometer (EIS) and Solar and Heliospheric Observatory/Solar Ultraviolet Measurement of Emitted Radiation of Fe IX lines emitted by the same level of the high energy configuration 3s 2 3p 5 4p. The intensity ratios of these lines are dependent on atomic physics parameters only and not on the physical parameters of the emitting plasma, so that they are excellent tools to verify the relative intensity calibration of high-resolution spectrometers that work in the 170-200 A and 700-850 A wavelength ranges. We carry out extensive atomic physics calculations to improve the accuracy of the predicted intensity ratio, and compare the results with simultaneous EIS-SUMER observations of an off-disk quiet Sun region. We were able to identify two ultraviolet lines in the SUMER spectrum that are emitted by the same level that emits one bright line in the EIS wavelength range. Comparison between predicted and measured intensity ratios, wavelengths and energy separation of Fe IX levels confirms the identifications we make. Blending and calibration uncertainties are discussed. The results of this work are important for cross-calibrating EIS and SUMER, as well as future instrumentation.

  17. A systems modelling framework for the design of integrated process control systems

    International Nuclear Information System (INIS)

    Lind, M.

    1983-12-01

    The paper describes a systems modelling methodology, called multilevel flow modelling, or MFM, which aims at describing complex production plants as designs, i.e. as systems having goals, functions and equipment realizing these functions. The modelling concepts are based on thermodynamics and lead to a system description in terms of multiple levels of interrelated mass or energy flow structures. The paper discusses as a basis for the modelling framework the general properties of artifacts or designs, characterizes the complexity of production systems and defines the MFM concepts which allow a consistent specification of goals and functions of these systems as generated in the process design. A modelling example is given and the application of the models for the design of plant control strategies is outlined. (author)

  18. Use of an operational model evaluation system for model intercomparison

    Energy Technology Data Exchange (ETDEWEB)

    Foster, K. T., LLNL

    1998-03-01

    The Atmospheric Release Advisory Capability (ARAC) is a centralized emergency response system used to assess the impact from atmospheric releases of hazardous materials. As part of an on- going development program, new three-dimensional diagnostic windfield and Lagrangian particle dispersion models will soon replace ARAC`s current operational windfield and dispersion codes. A prototype model performance evaluation system has been implemented to facilitate the study of the capabilities and performance of early development versions of these new models relative to ARAC`s current operational codes. This system provides tools for both objective statistical analysis using common performance measures and for more subjective visualization of the temporal and spatial relationships of model results relative to field measurements. Supporting this system is a database of processed field experiment data (source terms and meteorological and tracer measurements) from over 100 individual tracer releases.

  19. Modeling soft interface dominated systems

    NARCIS (Netherlands)

    Lamorgese, A.; Mauri, R.; Sagis, L.M.C.

    2017-01-01

    The two main continuum frameworks used for modeling the dynamics of soft multiphase systems are the Gibbs dividing surface model, and the diffuse interface model. In the former the interface is modeled as a two dimensional surface, and excess properties such as a surface density, or surface energy

  20. Data management system performance modeling

    Science.gov (United States)

    Kiser, Larry M.

    1993-01-01

    This paper discusses analytical techniques that have been used to gain a better understanding of the Space Station Freedom's (SSF's) Data Management System (DMS). The DMS is a complex, distributed, real-time computer system that has been redesigned numerous times. The implications of these redesigns have not been fully analyzed. This paper discusses the advantages and disadvantages for static analytical techniques such as Rate Monotonic Analysis (RMA) and also provides a rationale for dynamic modeling. Factors such as system architecture, processor utilization, bus architecture, queuing, etc. are well suited for analysis with a dynamic model. The significance of performance measures for a real-time system are discussed.

  1. Compiling models into real-time systems

    International Nuclear Information System (INIS)

    Dormoy, J.L.; Cherriaux, F.; Ancelin, J.

    1992-08-01

    This paper presents an architecture for building real-time systems from models, and model-compiling techniques. This has been applied for building a real-time model-based monitoring system for nuclear plants, called KSE, which is currently being used in two plants in France. We describe how we used various artificial intelligence techniques for building it: a model-based approach, a logical model of its operation, a declarative implementation of these models, and original knowledge-compiling techniques for automatically generating the real-time expert system from those models. Some of those techniques have just been borrowed from the literature, but we had to modify or invent other techniques which simply did not exist. We also discuss two important problems, which are often underestimated in the artificial intelligence literature: size, and errors. Our architecture, which could be used in other applications, combines the advantages of the model-based approach with the efficiency requirements of real-time applications, while in general model-based approaches present serious drawbacks on this point

  2. Compiling models into real-time systems

    International Nuclear Information System (INIS)

    Dormoy, J.L.; Cherriaux, F.; Ancelin, J.

    1992-08-01

    This paper presents an architecture for building real-time systems from models, and model-compiling techniques. This has been applied for building a real-time model-base monitoring system for nuclear plants, called KSE, which is currently being used in two plants in France. We describe how we used various artificial intelligence techniques for building it: a model-based approach, a logical model of its operation, a declarative implementation of these models, and original knowledge-compiling techniques for automatically generating the real-time expert system from those models. Some of those techniques have just been borrowed from the literature, but we had to modify or invent other techniques which simply did not exist. We also discuss two important problems, which are often underestimated in the artificial intelligence literature: size, and errors. Our architecture, which could be used in other applications, combines the advantages of the model-based approach with the efficiency requirements of real-time applications, while in general model-based approaches present serious drawbacks on this point

  3. A Test of the Interstellar Boundary EXplorer Ribbon Formation in the Outer Heliosheath

    Energy Technology Data Exchange (ETDEWEB)

    Gamayunov, Konstantin V.; Rassoul, Hamid [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Heerikhuisen, Jacob, E-mail: kgamayunov@fit.edu [Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2017-08-10

    NASA’s Interstellar Boundary EXplorer ( IBEX ) mission is imaging energetic neutral atoms (ENAs) propagating to Earth from the outer heliosphere and local interstellar medium (LISM). A dominant feature in all ENA maps is a ribbon of enhanced fluxes that was not predicted before IBEX . While more than a dozen models of the ribbon formation have been proposed, consensus has gathered around the so-called secondary ENA model. Two classes of secondary ENA models have been proposed; the first class assumes weak scattering of the energetic pickup protons in the LISM, and the second class assumes strong but spatially localized scattering. Here we present a numerical test of the “weak scattering” version of the secondary ENA model using our gyro-averaged kinetic model for the evolution of the phase-space distribution of protons in the outer heliosheath. As input for our test, we use distributions of the primary ENAs from our MHD-plasma/kinetic-neutral model of the heliosphere-LISM interaction. The magnetic field spectrum for the large-scale interstellar turbulence and an upper limit for the amplitude of small-scale local turbulence (SSLT) generated by protons are taken from observations by Voyager 1 in the LISM. The hybrid simulations of energetic protons are also used to set the bounding wavenumbers for the spectrum of SSLT. Our test supports the “weak scattering” version. This makes an additional solid step on the way to understanding the origin and formation of the IBEX ribbon and thus to improving our understanding of the interaction between the heliosphere and the LISM.

  4. Interplanetary Radiation and Internal Charging Environment Models for Solar Sails

    Science.gov (United States)

    Minow, Joseph I.; Altstatt, Richard L.; NeegaardParker, Linda

    2005-01-01

    A Solar Sail Radiation Environment (SSRE) model has been developed for defining charged particle environments over an energy range from 0.01 keV to 1 MeV for hydrogen ions, helium ions, and electrons. The SSRE model provides the free field charged particle environment required for characterizing energy deposition per unit mass, charge deposition, and dose rate dependent conductivity processes required to evaluate radiation dose and internal (bulk) charging processes in the solar sail membrane in interplanetary space. Solar wind and energetic particle measurements from instruments aboard the Ulysses spacecraft in a solar, near-polar orbit provide the particle data over a range of heliospheric latitudes used to derive the environment that can be used for radiation and charging environments for both high inclination 0.5 AU Solar Polar Imager mission and the 1.0 AU L1 solar missions. This paper describes the techniques used to model comprehensive electron, proton, and helium spectra over the range of particle energies of significance to energy and charge deposition in thin (less than 25 micrometers) solar sail materials.

  5. Modeling Adaptive Behavior for Systems Design

    DEFF Research Database (Denmark)

    Rasmussen, Jens

    1994-01-01

    Field studies in modern work systems and analysis of recent major accidents have pointed to a need for better models of the adaptive behavior of individuals and organizations operating in a dynamic and highly competitive environment. The paper presents a discussion of some key characteristics.......) The basic difference between the models of system functions used in engineering and design and those evolving from basic research within the various academic disciplines and finally 3.) The models and methods required for closed-loop, feedback system design....

  6. REQUIREMENTS FOR SYSTEMS DEVELOPMENT LIFE CYCLE MODELS FOR LARGE-SCALE DEFENSE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Kadir Alpaslan DEMIR

    2015-10-01

    Full Text Available TLarge-scale defense system projects are strategic for maintaining and increasing the national defense capability. Therefore, governments spend billions of dollars in the acquisition and development of large-scale defense systems. The scale of defense systems is always increasing and the costs to build them are skyrocketing. Today, defense systems are software intensive and they are either a system of systems or a part of it. Historically, the project performances observed in the development of these systems have been signifi cantly poor when compared to other types of projects. It is obvious that the currently used systems development life cycle models are insuffi cient to address today’s challenges of building these systems. Using a systems development life cycle model that is specifi cally designed for largescale defense system developments and is effective in dealing with today’s and near-future challenges will help to improve project performances. The fi rst step in the development a large-scale defense systems development life cycle model is the identifi cation of requirements for such a model. This paper contributes to the body of literature in the fi eld by providing a set of requirements for system development life cycle models for large-scale defense systems. Furthermore, a research agenda is proposed.

  7. Identifying optimal models to represent biochemical systems.

    Directory of Open Access Journals (Sweden)

    Mochamad Apri

    Full Text Available Biochemical systems involving a high number of components with intricate interactions often lead to complex models containing a large number of parameters. Although a large model could describe in detail the mechanisms that underlie the system, its very large size may hinder us in understanding the key elements of the system. Also in terms of parameter identification, large models are often problematic. Therefore, a reduced model may be preferred to represent the system. Yet, in order to efficaciously replace the large model, the reduced model should have the same ability as the large model to produce reliable predictions for a broad set of testable experimental conditions. We present a novel method to extract an "optimal" reduced model from a large model to represent biochemical systems by combining a reduction method and a model discrimination method. The former assures that the reduced model contains only those components that are important to produce the dynamics observed in given experiments, whereas the latter ensures that the reduced model gives a good prediction for any feasible experimental conditions that are relevant to answer questions at hand. These two techniques are applied iteratively. The method reveals the biological core of a model mathematically, indicating the processes that are likely to be responsible for certain behavior. We demonstrate the algorithm on two realistic model examples. We show that in both cases the core is substantially smaller than the full model.

  8. Revised sequence components power system models for unbalanced power system studies

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Akher, M. [Tunku Abdul Rahman Univ., Kuala Lumpur (Malaysia); Nor, K.-M. [Univ. of Technology Malaysia, Johor (Malaysia); Rashid, A.H.A. [Univ. of Malaya, Kuala Lumpur (Malaysia)

    2007-07-01

    The principle method of analysis using positive, negative, and zero-sequence networks has been used to examine the balanced power system under both balanced and unbalanced loading conditions. The significant advantage of the sequence networks is that the sequence networks become entirely uncoupled in the case of balanced three-phase power systems. The uncoupled sequence networks then can be solved in independent way such as in fault calculation programs. However, the hypothesis of balanced power systems cannot be considered in many cases due to untransposed transmission lines; multiphase line segments in a distribution power system; or transformer phase shifts which cannot be incorporated in the existing models. A revised sequence decoupled power system models for analyzing unbalanced power systems based on symmetrical networks was presented in this paper. These models included synchronous machines, transformers, transmission lines, and voltage regulators. The models were derived from their counterpart's models in phase coordinates frame of reference. In these models, the three sequence networks were fully decoupled with a three-phase coordinates features such as transformer phase shifts and transmission line coupling. The proposed models were used to develop an unbalanced power-flow program for analyzing both balanced and unbalanced networks. The power flow solution was identical to results obtained from a full phase coordinate three-phase power-flow program. 11 refs., 3 tabs.

  9. Model Reduction of Hybrid Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza

    gramians. Generalized gramians are the solutions to the observability and controllability Lyapunov inequalities. In the first framework the projection matrices are found based on the common generalized gramians. This framework preserves the stability of the original switched system for all switching...... is guaranteed to be preserved for arbitrary switching signal. To compute the common generalized gramians linear matrix inequalities (LMI’s) need to be solved. These LMI’s are not always feasible. In order to solve the problem of conservatism, the second framework is presented. In this method the projection......High-Technological solutions of today are characterized by complex dynamical models. A lot of these models have inherent hybrid/switching structure. Hybrid/switched systems are powerful models for distributed embedded systems design where discrete controls are applied to continuous processes...

  10. Discrete modelling of drapery systems

    Science.gov (United States)

    Thoeni, Klaus; Giacomini, Anna

    2016-04-01

    Drapery systems are an efficient and cost-effective measure in preventing and controlling rockfall hazards on rock slopes. The simplest form consists of a row of ground anchors along the top of the slope connected to a horizontal support cable from which a wire mesh is suspended down the face of the slope. Such systems are generally referred to as simple or unsecured draperies (Badger and Duffy 2012). Variations such as secured draperies, where a pattern of ground anchors is incorporated within the field of the mesh, and hybrid systems, where the upper part of an unsecured drapery is elevated to intercept rockfalls originating upslope of the installation, are becoming more and more popular. This work presents a discrete element framework for simulation of unsecured drapery systems and its variations. The numerical model is based on the classical discrete element method (DEM) and implemented into the open-source framework YADE (Šmilauer et al., 2010). The model takes all relevant interactions between block, drapery and slope into account (Thoeni et al., 2014) and was calibrated and validated based on full-scale experiments (Giacomini et al., 2012).The block is modelled as a rigid clump made of spherical particles which allows any shape to be approximated. The drapery is represented by a set of spherical particle with remote interactions. The behaviour of the remote interactions is governed by the constitutive behaviour of the wire and generally corresponds to a piecewise linear stress-strain relation (Thoeni et al., 2013). The same concept is used to model wire ropes. The rock slope is represented by rigid triangular elements where material properties (e.g., normal coefficient of restitution, friction angle) are assigned to each triangle. The capabilities of the developed model to simulate drapery systems and estimate the residual hazard involved with such systems is shown. References Badger, T.C., Duffy, J.D. (2012) Drapery systems. In: Turner, A.K., Schuster R

  11. An Empirical Model for Energy Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Rosewater, David Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Scott, Paul [TransPower, Poway, CA (United States)

    2016-03-17

    Improved models of energy storage systems are needed to enable the electric grid’s adaptation to increasing penetration of renewables. This paper develops a generic empirical model of energy storage system performance agnostic of type, chemistry, design or scale. Parameters for this model are calculated using test procedures adapted from the US DOE Protocol for Uniformly Measuring and Expressing the Performance of Energy Storage. We then assess the accuracy of this model for predicting the performance of the TransPower GridSaver – a 1 MW rated lithium-ion battery system that underwent laboratory experimentation and analysis. The developed model predicts a range of energy storage system performance based on the uncertainty of estimated model parameters. Finally, this model can be used to better understand the integration and coordination of energy storage on the electric grid.

  12. Structure of Energetic Particle Mediated Shocks Revisited

    International Nuclear Information System (INIS)

    Mostafavi, P.; Zank, G. P.; Webb, G. M.

    2017-01-01

    The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

  13. Structure of Energetic Particle Mediated Shocks Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Mostafavi, P.; Zank, G. P. [Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Webb, G. M. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2017-05-20

    The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

  14. Comparative Science and Space Weather Around the Heliosphere

    Science.gov (United States)

    Grande, Manuel; Andre, Nicolas; COSPAR/ILWS Roadmap Team

    2016-10-01

    Space weather refers to the variable state of the coupled space environment related to changing conditions on the Sun and in the terrestrial atmosphere. The presentation will focus on the critical missing knowledge or observables needed to significantly advance our modelling and forecasting capabilities throughout the solar system putting these in perspective to the recommendations in the recent COSPAR/ILWS roadmap. The COSPAR/ILWS RoadMap focuses on high-priority challenges in key areas of research leading to a better understanding of the space environment and a demonstrable improvement in the provision of timely, reliable information pertinent to effects on civilian space- and ground-based systems, for all stakeholders around the world. The RoadMap prioritizes those advances that can be made on short, intermediate and decadal time scales, identifying gaps and opportunities from a predominantly, but not exclusively, geocentric perspective. While discussion of space weather effects has so far largely been concerned to the near-Earth environment, there are significant present and future applications to the locations beyond, and to other planets. Most obviously, perhaps, are the radiation hazards experienced by astronauts on the way to, and on the surface of, the Moon and Mars. Indeed, the environment experienced by planetary spacecraft in transit and at their destinations is of course critical to their design and successful operation. The case of forthcoming missions to Jupiter and Europa is an extreme example. Moreover, such craft can provide information which in turn increases our understanding of geospace. One initiative is that under Horizon 2020, Europlanet RI will set up a Europlanet Planetary Space Weather Service (PSWS). PSWS will make five entirely new `toolkits' accessible to the research community and to industrial partners planning for space missions: - a General planetary space weather toolkit; Mars (in support of the ESA ExoMars missions to be launched

  15. A coordination model for ultra-large scale systems of systems

    Directory of Open Access Journals (Sweden)

    Manuela L. Bujorianu

    2013-11-01

    Full Text Available The ultra large multi-agent systems are becoming increasingly popular due to quick decay of the individual production costs and the potential of speeding up the solving of complex problems. Examples include nano-robots, or systems of nano-satellites for dangerous meteorite detection, or cultures of stem cells for organ regeneration or nerve repair. The topics associated with these systems are usually dealt within the theories of intelligent swarms or biologically inspired computation systems. Stochastic models play an important role and they are based on various formulations of the mechanical statistics. In these cases, the main assumption is that the swarm elements have a simple behaviour and that some average properties can be deduced for the entire swarm. In contrast, complex systems in areas like aeronautics are formed by elements with sophisticated behaviour, which are even autonomous. In situations like this, a new approach to swarm coordination is necessary. We present a stochastic model where the swarm elements are communicating autonomous systems, the coordination is separated from the component autonomous activity and the entire swarm can be abstracted away as a piecewise deterministic Markov process, which constitutes one of the most popular model in stochastic control. Keywords: ultra large multi-agent systems, system of systems, autonomous systems, stochastic hybrid systems.

  16. Data retrieval systems and models of information situations

    International Nuclear Information System (INIS)

    Jankowski, L.

    1984-01-01

    Demands placed on data retrieval systems and their basic parameters are given. According to the stage of development of data collection and processing, data retrieval systems may be divided into systems for the simple recording and provision of data, systems for recording and providing data with integrated statistical functions, and logical information systems. The structure is characterized of the said information systems as are methods of processing and representation of facts. The notion is defined of ''artificial intelligence'' in the development of logical information systems. The structure of representing knowledge in diverse forms of the model is decisive in logical information systems related to nuclear research. The main model elements are the characteristics of data, forms of representation and program. In dependence on the structure of data, the structure of the preparatory and transformation algorithms and on the aim of the system it is possible to classify data retrieval systems related to nuclear research and technology into five logical information models: linear, identification, advisory, theory-experiment models and problem solving models. The characteristics are given of the said models and examples of data retrieval systems for the individual models. (E.S.)

  17. Review of the systems biology of the immune system using agent-based models.

    Science.gov (United States)

    Shinde, Snehal B; Kurhekar, Manish P

    2018-06-01

    The immune system is an inherent protection system in vertebrate animals including human beings that exhibit properties such as self-organisation, self-adaptation, learning, and recognition. It interacts with the other allied systems such as the gut and lymph nodes. There is a need for immune system modelling to know about its complex internal mechanism, to understand how it maintains the homoeostasis, and how it interacts with the other systems. There are two types of modelling techniques used for the simulation of features of the immune system: equation-based modelling (EBM) and agent-based modelling. Owing to certain shortcomings of the EBM, agent-based modelling techniques are being widely used. This technique provides various predictions for disease causes and treatments; it also helps in hypothesis verification. This study presents a review of agent-based modelling of the immune system and its interactions with the gut and lymph nodes. The authors also review the modelling of immune system interactions during tuberculosis and cancer. In addition, they also outline the future research directions for the immune system simulation through agent-based techniques such as the effects of stress on the immune system, evolution of the immune system, and identification of the parameters for a healthy immune system.

  18. Stochastic Models of Polymer Systems

    Science.gov (United States)

    2016-01-01

    Distribution Unlimited Final Report: Stochastic Models of Polymer Systems The views, opinions and/or findings contained in this report are those of the...ADDRESS. Princeton University PO Box 0036 87 Prospect Avenue - 2nd floor Princeton, NJ 08544 -2020 14-Mar-2014 ABSTRACT Number of Papers published in...peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: Stochastic Models of Polymer Systems Report Title

  19. Modelling and Control of Thermal System

    Directory of Open Access Journals (Sweden)

    Vratislav Hladky

    2014-01-01

    Full Text Available Work presented here deals with the modelling of thermal processes in a thermal system consisting of direct and indirect heat exchangers. The overal thermal properties of the medium and the system itself such as liquid mixing or heat capacity are shortly analysed and their features required for modelling are reasoned and therefore simplified or neglected. Special attention is given to modelling heat losses radiated into the surroundings through the walls as they are the main issue of the effective work with the heat systems. Final part of the paper proposes several ways of controlling the individual parts’ temperatures as well as the temperature of the system considering heating elements or flowage rate as actuators.

  20. The radionuclide migration model in river system

    International Nuclear Information System (INIS)

    Zhukova, O.M.; Shiryaeva, N.M.; Myshkina, M.K.; Shagalova, Eh.D.; Denisova, V.V.; Skurat, V.V.

    2001-01-01

    It was propose the model of radionuclide migration in river system based on principle of the compartmental model at hydraulically stationary and chemically equilibrium conditions of interaction of radionuclides in system water-dredge, water-sediments. Different conditions of radioactive contamination entry in river system were considered. The model was verified on the data of radiation monitoring of Iput' river

  1. Model predictive control based on reduced order models applied to belt conveyor system.

    Science.gov (United States)

    Chen, Wei; Li, Xin

    2016-11-01

    In the paper, a model predictive controller based on reduced order model is proposed to control belt conveyor system, which is an electro-mechanics complex system with long visco-elastic body. Firstly, in order to design low-degree controller, the balanced truncation method is used for belt conveyor model reduction. Secondly, MPC algorithm based on reduced order model for belt conveyor system is presented. Because of the error bound between the full-order model and reduced order model, two Kalman state estimators are applied in the control scheme to achieve better system performance. Finally, the simulation experiments are shown that balanced truncation method can significantly reduce the model order with high-accuracy and model predictive control based on reduced-model performs well in controlling the belt conveyor system. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  2. Feature-based component model for design of embedded systems

    Science.gov (United States)

    Zha, Xuan Fang; Sriram, Ram D.

    2004-11-01

    An embedded system is a hybrid of hardware and software, which combines software's flexibility and hardware real-time performance. Embedded systems can be considered as assemblies of hardware and software components. An Open Embedded System Model (OESM) is currently being developed at NIST to provide a standard representation and exchange protocol for embedded systems and system-level design, simulation, and testing information. This paper proposes an approach to representing an embedded system feature-based model in OESM, i.e., Open Embedded System Feature Model (OESFM), addressing models of embedded system artifacts, embedded system components, embedded system features, and embedded system configuration/assembly. The approach provides an object-oriented UML (Unified Modeling Language) representation for the embedded system feature model and defines an extension to the NIST Core Product Model. The model provides a feature-based component framework allowing the designer to develop a virtual embedded system prototype through assembling virtual components. The framework not only provides a formal precise model of the embedded system prototype but also offers the possibility of designing variation of prototypes whose members are derived by changing certain virtual components with different features. A case study example is discussed to illustrate the embedded system model.

  3. An expert system for dispersion model interpretation

    International Nuclear Information System (INIS)

    Skyllingstad, E.D.; Ramsdell, J.V.

    1988-10-01

    A prototype expert system designed to diagnose dispersion model uncertainty is described in this paper with application to a puff transport model. The system obtains qualitative information from the model user and through an expert-derived knowledge base, performs a rating of the current simulation. These results can then be used in combination with dispersion model output for deciding appropriate evacuation measures. Ultimately, the goal of this work is to develop an expert system that may be operated accurately by an individual uneducated in meteorology or dispersion modeling. 5 refs., 3 figs

  4. Modelling energy systems for developing countries

    International Nuclear Information System (INIS)

    Urban, F.; Benders, R.M.J.; Moll, H.C.

    2007-01-01

    Developing countries' energy use is rapidly increasing, which affects global climate change and global and regional energy settings. Energy models are helpful for exploring the future of developing and industrialised countries. However, energy systems of developing countries differ from those of industrialised countries, which has consequences for energy modelling. New requirements need to be met by present-day energy models to adequately explore the future of developing countries' energy systems. This paper aims to assess if the main characteristics of developing countries are adequately incorporated in present-day energy models. We first discuss these main characteristics, focusing particularly on developing Asia, and then present a model comparison of 12 selected energy models to test their suitability for developing countries. We conclude that many models are biased towards industrialised countries, neglecting main characteristics of developing countries, e.g. the informal economy, supply shortages, poor performance of the power sector, structural economic change, electrification, traditional bio-fuels, urban-rural divide. To more adequately address the energy systems of developing countries, energy models have to be adjusted and new models have to be built. We therefore indicate how to improve energy models for increasing their suitability for developing countries and give advice on modelling techniques and data requirements

  5. Modelling the Replication Management in Information Systems

    Directory of Open Access Journals (Sweden)

    Cezar TOADER

    2017-01-01

    Full Text Available In the modern economy, the benefits of Web services are significant because they facilitates the activities automation in the framework of Internet distributed businesses as well as the cooperation between organizations through interconnection process running in the computer systems. This paper presents the development stages of a model for a reliable information system. This paper describes the communication between the processes within the distributed system, based on the message exchange, and also presents the problem of distributed agreement among processes. A list of objectives for the fault-tolerant systems is defined and a framework model for distributed systems is proposed. This framework makes distinction between management operations and execution operations. The proposed model promotes the use of a central process especially designed for the coordination and control of other application processes. The execution phases and the protocols for the management and the execution components are presented. This model of a reliable system could be a foundation for an entire class of distributed systems models based on the management of replication process.

  6. Systems Engineering Model for ART Energy Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Mendez Cruz, Carmen Margarita [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rochau, Gary E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wilson, Mollye C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-02-01

    The near-term objective of the EC team is to establish an operating, commercially scalable Recompression Closed Brayton Cycle (RCBC) to be constructed for the NE - STEP demonstration system (demo) with the lowest risk possible. A systems engineering approach is recommended to ensure adequate requirements gathering, documentation, and mode ling that supports technology development relevant to advanced reactors while supporting crosscut interests in potential applications. A holistic systems engineering model was designed for the ART Energy Conversion program by leveraging Concurrent Engineering, Balance Model, Simplified V Model, and Project Management principles. The resulting model supports the identification and validation of lifecycle Brayton systems requirements, and allows designers to detail system-specific components relevant to the current stage in the lifecycle, while maintaining a holistic view of all system elements.

  7. System dynamics modelling of situation awareness

    CSIR Research Space (South Africa)

    Oosthuizen, R

    2015-11-01

    Full Text Available . The feedback loops and delays in the Command and Control system also contribute to the complex dynamic behavior. This paper will build on existing situation awareness models to develop a System Dynamics model to support a qualitative investigation through...

  8. Modeling the Dynamic Digestive System Microbiome

    Directory of Open Access Journals (Sweden)

    Anne M. Estes

    2015-08-01

    Full Text Available “Modeling the Dynamic Digestive System Microbiome” is a hands-on activity designed to demonstrate the dynamics of microbiome ecology using dried pasta and beans to model disturbance events in the human digestive system microbiome. This exercise demonstrates how microbiome diversity is influenced by: 1 niche availability and habitat space and 2 a major disturbance event, such as antibiotic use. Students use a pictorial key to examine prepared models of digestive system microbiomes to determine what the person with the microbiome “ate.” Students then model the effect of taking antibiotics by removing certain “antibiotic sensitive” pasta. Finally, they add in “environmental microbes” or “native microbes” to recolonize the digestive system, determine how resilient their model microbome community is to disturbance, and discuss the implications. Throughout the exercise, students discuss differences in the habitat space available and microbiome community diversity. This exercise can be modified to discuss changes in the microbiome due to diet shifts and the emergence of antibiotic resistance in more depth.

  9. Stirling Engine Dynamic System Modeling

    Science.gov (United States)

    Nakis, Christopher G.

    2004-01-01

    The Thermo-Mechanical systems branch at the Glenn Research Center focuses a large amount time on Stirling engines. These engines will be used on missions where solar power is inefficient, especially in deep space. I work with Tim Regan and Ed Lewandowski who are currently developing and validating a mathematical model for the Stirling engines. This model incorporates all aspects of the system including, mechanical, electrical and thermodynamic components. Modeling is done through Simplorer, a program capable of running simulations of the model. Once created and then proven to be accurate, a model is used for developing new ideas for engine design. My largest specific project involves varying key parameters in the model and quantifying the results. This can all be done relatively trouble-free with the help of Simplorer. Once the model is complete, Simplorer will do all the necessary calculations. The more complicated part of this project is determining which parameters to vary. Finding key parameters depends on the potential for a value to be independently altered in the design. For example, a change in one dimension may lead to a proportional change to the rest of the model, and no real progress is made. Also, the ability for a changed value to have a substantial impact on the outputs of the system is important. Results will be condensed into graphs and tables with the purpose of better communication and understanding of the data. With the changing of these parameters, a more optimal design can be created without having to purchase or build any models. Also, hours and hours of results can be simulated in minutes. In the long run, using mathematical models can save time and money. Along with this project, I have many other smaller assignments throughout the summer. My main goal is to assist in the processes of model development, validation and testing.

  10. Executive Information Systems' Multidimensional Models

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available Executive Information Systems are design to improve the quality of strategic level of management in organization through a new type of technology and several techniques for extracting, transforming, processing, integrating and presenting data in such a way that the organizational knowledge filters can easily associate with this data and turn it into information for the organization. These technologies are known as Business Intelligence Tools. But in order to build analytic reports for Executive Information Systems (EIS in an organization we need to design a multidimensional model based on the business model from the organization. This paper presents some multidimensional models that can be used in EIS development and propose a new model that is suitable for strategic business requests.

  11. Balmorel open source energy system model

    DEFF Research Database (Denmark)

    Wiese, Frauke; Bramstoft, Rasmus; Koduvere, Hardi

    2018-01-01

    As the world progresses towards a cleaner energy future with more variable renewable energy sources, energy system models are required to deal with new challenges. This article describes design, development and applications of the open source energy system model Balmorel, which is a result...... of a long and fruitful cooperation between public and private institutions within energy system research and analysis. The purpose of the article is to explain the modelling approach, to highlight strengths and challenges of the chosen approach, to create awareness about the possible applications...... of Balmorel as well as to inspire to new model developments and encourage new users to join the community. Some of the key strengths of the model are the flexible handling of the time and space dimensions and the combination of operation and investment optimisation. Its open source character enables diverse...

  12. Numerical Modeling of Microelectrochemical Systems

    DEFF Research Database (Denmark)

    Adesokan, Bolaji James

    incorporates the finite size of ionic species in the transport equation. The model presents a more appropriate boundary conditions which describe the modified Butler-Volmer reaction kinetics and account for the surface capacitance of the thin electric double layer. We also have found analytical solution...... at the electrode in a microelectrochemical system. In our analysis, we account for the finite size properties of ions in the mass and the charge transport of ionic species in an electrochemical system. This term characterizes the saturation of the ionic species close to the electrode surface. We then analyse......The PhD dissertation is concerned with mathematical modeling and simulation of electrochemical systems. The first three chapters of the thesis consist of the introductory part, the model development chapter and the chapter on the summary of the main results. The remaining three chapters report...

  13. Agent-based Modeling Methodology for Analyzing Weapons Systems

    Science.gov (United States)

    2015-03-26

    technique involve model structure, system representation and the degree of validity, coupled with the simplicity, of the overall model. ABM is best suited... system representation of the air combat system . We feel that a simulation model that combines ABM with equation-based representation of weapons and...AGENT-BASED MODELING METHODOLOGY FOR ANALYZING WEAPONS SYSTEMS THESIS Casey D. Connors, Major, USA

  14. A control strategy for electro-magneto-mechanical system based on virtual system model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong Youn; Heo, Hoon [Dept. of Control and Instrumentation Engineering, Korea University, Seoul (Korea, Republic of); Yun, Young Min [TPC Mechatronics Co., Ltd., Incheon (Korea, Republic of)

    2016-09-15

    A new approach to the control of electro-magneto-mechanical system is proposed in this paper. Conventionally, these systems are controlled based on the Maxwell system model via an on-off or PID control technique, which displays acceptable performance in the low frequency region, but not in the high frequency region where position control performance is greatly degraded. In order to improve the performance, a newly developed virtual 2nd order system modeling technique, SSID, is adopted for a complex electro-magnetomechanical system in the study. This technique states that any unknown system exposed to a random disturbance with unknown intensity can be identified in terms of a virtual 2nd order system model via the inverse process of a certain stochastic analysis. As a typical hybrid system, a solenoid valve is used as the target electro-magneto-mechanical system to study the modeling of the virtual 2nd order system. In order to confirm the performance of the proposed control strategy, autotuning PID controller in PWM mode is utilized. Simulations based on the conventional Maxwell system model with control via the bang-bang, autotuning PID, and the proposed virtual 2nd order system model approaches are conducted using MATLAB Simulink. Performance of these three systems in the low and high frequency bands is also compared. The simulation results reveal that the control performance of the virtual 2nd order system model is much improved compared with that of the Maxwell system model under autotuning PID and bang-bang controls in both low and high frequency regions, where the error is drastically reduced to approximately 1/5 of the original value.

  15. Modeling of Generic Slung Load System

    DEFF Research Database (Denmark)

    Bisgaard, Morten; Bendtsen, Jan Dimon; la Cour-Harbo, Anders

    2009-01-01

    This paper presents the result of the modelling and verification of a generic slung load system using a small-scale helicopter. The model is intended for use in simulation, pilot training, estimation, and control. The model is derived using a redundant coordinate formulation based on Gauss...... slackening and tightening as well as aerodynamic coupling between the helicopter and the load. Furthermore, it is shown how the model can be easily used for multi-lift systems either with multiple helicopters or multiple loads. A numerical stabilisation algorithm is introduced and finally the use...... of the model is illustrated through simulations and flight verifications.  ...

  16. Qualitative models for space system engineering

    Science.gov (United States)

    Forbus, Kenneth D.

    1990-01-01

    The objectives of this project were: (1) to investigate the implications of qualitative modeling techniques for problems arising in the monitoring, diagnosis, and design of Space Station subsystems and procedures; (2) to identify the issues involved in using qualitative models to enhance and automate engineering functions. These issues include representing operational criteria, fault models, alternate ontologies, and modeling continuous signals at a functional level of description; and (3) to develop a prototype collection of qualitative models for fluid and thermal systems commonly found in Space Station subsystems. Potential applications of qualitative modeling to space-systems engineering, including the notion of intelligent computer-aided engineering are summarized. Emphasis is given to determining which systems of the proposed Space Station provide the most leverage for study, given the current state of the art. Progress on using qualitative models, including development of the molecular collection ontology for reasoning about fluids, the interaction of qualitative and quantitative knowledge in analyzing thermodynamic cycles, and an experiment on building a natural language interface to qualitative reasoning is reported. Finally, some recommendations are made for future research.

  17. Model Checking Real-Time Systems

    DEFF Research Database (Denmark)

    Bouyer, Patricia; Fahrenberg, Uli; Larsen, Kim Guldstrand

    2018-01-01

    This chapter surveys timed automata as a formalism for model checking real-time systems. We begin with introducing the model, as an extension of finite-state automata with real-valued variables for measuring time. We then present the main model-checking results in this framework, and give a hint...

  18. LOCAL INTERSTELLAR HYDROGEN'S DISAPPEARANCE AT 1 AU: FOUR YEARS OF IBEX IN THE RISING SOLAR CYCLE

    International Nuclear Information System (INIS)

    Saul, Lukas; Rodríguez, Diego; Scheer, Juergen; Wurz, Peter; Bzowski, Maciej; Kubiak, Marzena; Sokół, Justina; Fuselier, Stephen; McComas, Dave; Möbius, Eberhard

    2013-01-01

    NASA's Interstellar Boundary Explorer (IBEX) mission has recently opened a new window on the interstellar medium (ISM) by imaging neutral atoms. One ''bright'' feature in the sky is the interstellar wind flowing into the solar system. Composed of remnants of stellar explosions as well as primordial gas and plasma, the ISM is by no means uniform. The interaction of the local ISM with the solar wind shapes our heliospheric environment with hydrogen being the dominant component of the very local ISM. In this paper, we report on direct sampling of the neutral hydrogen of the local ISM over four years of IBEX observations. The hydrogen wind observed at 1 AU has decreased and nearly disappeared as the solar activity has increased over the last four years; the signal at 1 AU has dropped off in 2012 by a factor of ∼8 to near background levels. The longitudinal offset has also increased with time presumably due to greater radiation pressure deflecting the interstellar wind. We present longitudinal and latitudinal arrival direction measurements of the bulk flow as measured over four years beginning at near solar minimum conditions. The H distribution we observe at 1 AU is expected to be different from that outside the heliopause due to ionization, photon pressure, gravity, and filtration by interactions with heliospheric plasma populations. These observations provide an important benchmark for modeling of the global heliospheric interaction. Based on these observations we suggest a further course of scientific action to observe neutral hydrogen over a full solar cycle with IBEX.

  19. DRAPING OF THE INTERSTELLAR MAGNETIC FIELD OVER THE HELIOPAUSE: A PASSIVE FIELD MODEL

    International Nuclear Information System (INIS)

    Isenberg, Philip A.; Forbes, Terry G.; Möbius, Eberhard

    2015-01-01

    As the local interstellar plasma flows past our heliosphere, it is slowed and deflected around the magnetic obstacle of the heliopause. The interstellar magnetic field, frozen into this plasma, then becomes draped around the heliopause in a characteristic manner. We derive the analytical solution for this draped magnetic field in the limit of weak field intensity, assuming an ideal potential flow around the heliopause, which we model as a Rankine half-body. We compare the structure of the model magnetic field with observed properties of the Interstellar Boundary Explorer (IBEX) ribbon and with in situ observations at the Voyager 1 spacecraft. We find reasonable qualitative agreement, given the idealizations of the model. This agreement lends support to the secondary ENA model of the IBEX ribbon and to the interpretation that Voyager 1 has crossed the heliopause. We also predict that the magnetic field measured by Voyager 2 after it crosses the heliopause will not be significantly rotated away from the direction of the undisturbed interstellar field

  20. Using A Model-Based Systems Engineering Approach For Exploration Medical System Development

    Science.gov (United States)

    Hanson, A.; Mindock, J.; McGuire, K.; Reilly, J.; Cerro, J.; Othon, W.; Rubin, D.; Urbina, M.; Canga, M.

    2017-01-01

    NASA's Human Research Program's Exploration Medical Capabilities (ExMC) element is defining the medical system needs for exploration class missions. ExMC's Systems Engineering (SE) team will play a critical role in successful design and implementation of the medical system into exploration vehicles. The team's mission is to "Define, develop, validate, and manage the technical system design needed to implement exploration medical capabilities for Mars and test the design in a progression of proving grounds." Development of the medical system is being conducted in parallel with exploration mission architecture and vehicle design development. Successful implementation of the medical system in this environment will require a robust systems engineering approach to enable technical communication across communities to create a common mental model of the emergent engineering and medical systems. Model-Based Systems Engineering (MBSE) improves shared understanding of system needs and constraints between stakeholders and offers a common language for analysis. The ExMC SE team is using MBSE techniques to define operational needs, decompose requirements and architecture, and identify medical capabilities needed to support human exploration. Systems Modeling Language (SysML) is the specific language the SE team is utilizing, within an MBSE approach, to model the medical system functional needs, requirements, and architecture. Modeling methods are being developed through the practice of MBSE within the team, and tools are being selected to support meta-data exchange as integration points to other system models are identified. Use of MBSE is supporting the development of relationships across disciplines and NASA Centers to build trust and enable teamwork, enhance visibility of team goals, foster a culture of unbiased learning and serving, and be responsive to customer needs. The MBSE approach to medical system design offers a paradigm shift toward greater integration between

  1. Graphical Model Debugger Framework for Embedded Systems

    DEFF Research Database (Denmark)

    Zeng, Kebin

    2010-01-01

    Model Driven Software Development has offered a faster way to design and implement embedded real-time software by moving the design to a model level, and by transforming models to code. However, the testing of embedded systems has remained at the code level. This paper presents a Graphical Model...... Debugger Framework, providing an auxiliary avenue of analysis of system models at runtime by executing generated code and updating models synchronously, which allows embedded developers to focus on the model level. With the model debugger, embedded developers can graphically test their design model...

  2. Combining multimedia models with integrated urban water system models for micropollutants

    DEFF Research Database (Denmark)

    De Keyser, W.; Gevaert, V.; Verdonck, F.

    2010-01-01

    Integrated urban water system (IUWS) modeling aims at assessing the quality of the surface water receiving the urban emissions through sewage treatment plants, combined sewer overflows (CSOS) and stormwater drainage systems However, some micropollutants tend to appear in more than one environmental...... medium (air, water, sediment, soil, groundwater, etc) In this work, a multimedia fate and transport model (MFTM) is "wrapped around" a dynamic IUWS model for organic micropollutants to enable integrated environmental assessment The combined model was tested on a hypothetical catchment using two scenarios...... on the one hand a reference scenario with a combined sewerage system and on the other hand a stormwater infiltration pond scenario, as an example of a sustainable urban drainage system (SUDS) A case for Bis(2-ethylhexyl) phthalate (DEHP) was simulated and resulted in reduced surface water concentrations...

  3. Double radio sources and the new approach to cosmical plasma physics

    International Nuclear Information System (INIS)

    Alfven, H.

    1978-01-01

    The methodology of cosmic plasma physics is discussed. It is hazardous to try to describe plasma phenomena by theories which have not been carefully tested experimentally. One present approach is to rely on laboratory measurements and in situ measurements in the magnetosphere and heliosphere, and to approach galactic phenomena by scaling up the wellknown phenomena to galactic dimensions. A summary is given of laboratory investigations of electric double layers, a phenomenon which is known to be very important in laboratory discharges. A summary is also given of the in situ measurements in the magnetosphere by which the importance of electric double layers in the Earth's surrounding is established. The scaling laws between laboratory and magnetospheric double layers are studied. The successful scaling between laboratory and magnetospheric phenomena encourages an extrapolation to heliospheric phenomena. A further extrapolation to galactic phenomena leads to a theory of double radio sources. In analogy with the Sun which, acting as a homopolar inductor, energizes the heliospheric current system, a rotating magnetized galaxy should produce a similar current system. From analogy with laboratory and magnetospheric current systems it is argued that the galactic current might produce double layers where a large energy dissipation takes place. This leads to a theory of the double radio sources which, within the necessary wide limits of uncertainty, is quantitatively reconcilable with observations. (Auth.)

  4. Natural gas transmission and distribution model of the National Energy Modeling System

    International Nuclear Information System (INIS)

    1997-02-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of Integrated Analysis and Forecasting of the Energy Information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. From 1982 through 1993, the Intermediate Future Forecasting System (IFFS) was used by the EIA for its analyses, and the Gas Analysis Modeling System (GAMS) was used within IFFS to represent natural gas markets. Prior to 1982, the Midterm Energy Forecasting System (MEFS), also referred to as the Project Independence Evaluation System (PIES), was employed. NEMS was developed to enhance and update EIA's modeling capability by internally incorporating models of energy markets that had previously been analyzed off-line. In addition, greater structural detail in NEMS permits the analysis of a broader range of energy issues. The time horizon of NEMS is the midterm period (i.e., through 2015). In order to represent the regional differences in energy markets, the component models of NEMS function at regional levels appropriate for the markets represented, with subsequent aggregation/disaggregation to the Census Division level for reporting purposes

  5. Natural gas transmission and distribution model of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-02-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of Integrated Analysis and Forecasting of the Energy Information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. From 1982 through 1993, the Intermediate Future Forecasting System (IFFS) was used by the EIA for its analyses, and the Gas Analysis Modeling System (GAMS) was used within IFFS to represent natural gas markets. Prior to 1982, the Midterm Energy Forecasting System (MEFS), also referred to as the Project Independence Evaluation System (PIES), was employed. NEMS was developed to enhance and update EIA`s modeling capability by internally incorporating models of energy markets that had previously been analyzed off-line. In addition, greater structural detail in NEMS permits the analysis of a broader range of energy issues. The time horizon of NEMS is the midterm period (i.e., through 2015). In order to represent the regional differences in energy markets, the component models of NEMS function at regional levels appropriate for the markets represented, with subsequent aggregation/disaggregation to the Census Division level for reporting purposes.

  6. A hierarchy for modeling high speed propulsion systems

    Science.gov (United States)

    Hartley, Tom T.; Deabreu, Alex

    1991-01-01

    General research efforts on reduced order propulsion models for control systems design are overviewed. Methods for modeling high speed propulsion systems are discussed including internal flow propulsion systems that do not contain rotating machinery such as inlets, ramjets, and scramjets. The discussion is separated into four sections: (1) computational fluid dynamics model for the entire nonlinear system or high order nonlinear models; (2) high order linearized model derived from fundamental physics; (3) low order linear models obtained from other high order models; and (4) low order nonlinear models. Included are special considerations on any relevant control system designs. The methods discussed are for the quasi-one dimensional Euler equations of gasdynamic flow. The essential nonlinear features represented are large amplitude nonlinear waves, moving normal shocks, hammershocks, subsonic combustion via heat addition, temperature dependent gases, detonation, and thermal choking.

  7. Structural system identification: Structural dynamics model validation

    Energy Technology Data Exchange (ETDEWEB)

    Red-Horse, J.R.

    1997-04-01

    Structural system identification is concerned with the development of systematic procedures and tools for developing predictive analytical models based on a physical structure`s dynamic response characteristics. It is a multidisciplinary process that involves the ability (1) to define high fidelity physics-based analysis models, (2) to acquire accurate test-derived information for physical specimens using diagnostic experiments, (3) to validate the numerical simulation model by reconciling differences that inevitably exist between the analysis model and the experimental data, and (4) to quantify uncertainties in the final system models and subsequent numerical simulations. The goal of this project was to develop structural system identification techniques and software suitable for both research and production applications in code and model validation.

  8. Visual prosthesis wireless energy transfer system optimal modeling.

    Science.gov (United States)

    Li, Xueping; Yang, Yuan; Gao, Yong

    2014-01-16

    Wireless energy transfer system is an effective way to solve the visual prosthesis energy supply problems, theoretical modeling of the system is the prerequisite to do optimal energy transfer system design. On the basis of the ideal model of the wireless energy transfer system, according to visual prosthesis application condition, the system modeling is optimized. During the optimal modeling, taking planar spiral coils as the coupling devices between energy transmitter and receiver, the effect of the parasitic capacitance of the transfer coil is considered, and especially the concept of biological capacitance is proposed to consider the influence of biological tissue on the energy transfer efficiency, resulting in the optimal modeling's more accuracy for the actual application. The simulation data of the optimal model in this paper is compared with that of the previous ideal model, the results show that under high frequency condition, the parasitic capacitance of inductance and biological capacitance considered in the optimal model could have great impact on the wireless energy transfer system. The further comparison with the experimental data verifies the validity and accuracy of the optimal model proposed in this paper. The optimal model proposed in this paper has a higher theoretical guiding significance for the wireless energy transfer system's further research, and provide a more precise model reference for solving the power supply problem in visual prosthesis clinical application.

  9. Hybrid Energy System Modeling in Modelica

    Energy Technology Data Exchange (ETDEWEB)

    William R. Binder; Christiaan J. J. Paredis; Humberto E. Garcia

    2014-03-01

    In this paper, a Hybrid Energy System (HES) configuration is modeled in Modelica. Hybrid Energy Systems (HES) have as their defining characteristic the use of one or more energy inputs, combined with the potential for multiple energy outputs. Compared to traditional energy systems, HES provide additional operational flexibility so that high variability in both energy production and consumption levels can be absorbed more effectively. This is particularly important when including renewable energy sources, whose output levels are inherently variable, determined by nature. The specific HES configuration modeled in this paper include two energy inputs: a nuclear plant, and a series of wind turbines. In addition, the system produces two energy outputs: electricity and synthetic fuel. The models are verified through simulations of the individual components, and the system as a whole. The simulations are performed for a range of component sizes, operating conditions, and control schemes.

  10. Agent-Based Modeling in Systems Pharmacology.

    Science.gov (United States)

    Cosgrove, J; Butler, J; Alden, K; Read, M; Kumar, V; Cucurull-Sanchez, L; Timmis, J; Coles, M

    2015-11-01

    Modeling and simulation (M&S) techniques provide a platform for knowledge integration and hypothesis testing to gain insights into biological systems that would not be possible a priori. Agent-based modeling (ABM) is an M&S technique that focuses on describing individual components rather than homogenous populations. This tutorial introduces ABM to systems pharmacologists, using relevant case studies to highlight how ABM-specific strengths have yielded success in the area of preclinical mechanistic modeling.

  11. Risk Modeling of Interdependent Complex Systems of Systems: Theory and Practice.

    Science.gov (United States)

    Haimes, Yacov Y

    2018-01-01

    The emergence of the complexity characterizing our systems of systems (SoS) requires a reevaluation of the way we model, assess, manage, communicate, and analyze the risk thereto. Current models for risk analysis of emergent complex SoS are insufficient because too often they rely on the same risk functions and models used for single systems. These models commonly fail to incorporate the complexity derived from the networks of interdependencies and interconnectedness (I-I) characterizing SoS. There is a need to reevaluate currently practiced risk analysis to respond to this reality by examining, and thus comprehending, what makes emergent SoS complex. The key to evaluating the risk to SoS lies in understanding the genesis of characterizing I-I of systems manifested through shared states and other essential entities within and among the systems that constitute SoS. The term "essential entities" includes shared decisions, resources, functions, policies, decisionmakers, stakeholders, organizational setups, and others. This undertaking can be accomplished by building on state-space theory, which is fundamental to systems engineering and process control. This article presents a theoretical and analytical framework for modeling the risk to SoS with two case studies performed with the MITRE Corporation and demonstrates the pivotal contributions made by shared states and other essential entities to modeling and analysis of the risk to complex SoS. A third case study highlights the multifarious representations of SoS, which require harmonizing the risk analysis process currently applied to single systems when applied to complex SoS. © 2017 Society for Risk Analysis.

  12. Analytical performance modeling for computer systems

    CERN Document Server

    Tay, Y C

    2013-01-01

    This book is an introduction to analytical performance modeling for computer systems, i.e., writing equations to describe their performance behavior. It is accessible to readers who have taken college-level courses in calculus and probability, networking and operating systems. This is not a training manual for becoming an expert performance analyst. Rather, the objective is to help the reader construct simple models for analyzing and understanding the systems that they are interested in.Describing a complicated system abstractly with mathematical equations requires a careful choice of assumpti

  13. Modeling Of Proton Exchange Membrane Fuel Cell Systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh

    The objective of this doctoral thesis was to develop reliable steady-state and transient component models suitable to asses-, develop- and optimize proton exchange membrane (PEM) fuel cell systems. Several components in PEM fuel cell systems were characterized and modeled. The developed component...... cell systems. Consequences of indirectly fueling PEM stacks with hydrocarbons using reforming technology were investigated using a PEM stack model including CO poisoning kinetics and a transient Simulink steam reforming system model. Aspects regarding the optimization of PEM fuel cell systems...

  14. A Multi-Model Approach for System Diagnosis

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad; Bækgaard, Mikkel Ask Buur

    2007-01-01

    A multi-model approach for system diagnosis is presented in this paper. The relation with fault diagnosis as well as performance validation is considered. The approach is based on testing a number of pre-described models and find which one is the best. It is based on an active approach......,i.e. an auxiliary input to the system is applied. The multi-model approach is applied on a wind turbine system....

  15. Systems and context modeling approach to requirements analysis

    Science.gov (United States)

    Ahuja, Amrit; Muralikrishna, G.; Patwari, Puneet; Subhrojyoti, C.; Swaminathan, N.; Vin, Harrick

    2014-08-01

    Ensuring completeness and correctness of the requirements for a complex system such as the SKA is challenging. Current system engineering practice includes developing a stakeholder needs definition, a concept of operations, and defining system requirements in terms of use cases and requirements statements. We present a method that enhances this current practice into a collection of system models with mutual consistency relationships. These include stakeholder goals, needs definition and system-of-interest models, together with a context model that participates in the consistency relationships among these models. We illustrate this approach by using it to analyze the SKA system requirements.

  16. High-level PC-based laser system modeling

    Science.gov (United States)

    Taylor, Michael S.

    1991-05-01

    Since the inception of the Strategic Defense Initiative (SDI) there have been a multitude of comparison studies done in an attempt to evaluate the effectiveness and relative sizes of complementary, and sometimes competitive, laser weapon systems. It became more and more apparent that what the systems analyst needed was not only a fast, but a cost effective way to perform high-level trade studies. In the present investigation, a general procedure is presented for the development of PC-based algorithmic systems models for laser systems. This procedure points out all of the major issues that should be addressed in the design and development of such a model. Issues addressed include defining the problem to be modeled, defining a strategy for development, and finally, effective use of the model once developed. Being a general procedure, it will allow a systems analyst to develop a model to meet specific needs. To illustrate this method of model development, a description of the Strategic Defense Simulation - Design To (SDS-DT) model developed and used by Science Applications International Corporation (SAIC) is presented. SDS-DT is a menu-driven, fast executing, PC-based program that can be used to either calculate performance, weight, volume, and cost values for a particular design or, alternatively, to run parametrics on particular system parameters to perhaps optimize a design.

  17. Applying Modeling Tools to Ground System Procedures

    Science.gov (United States)

    Di Pasquale, Peter

    2012-01-01

    As part of a long-term effort to revitalize the Ground Systems (GS) Engineering Section practices, Systems Modeling Language (SysML) and Business Process Model and Notation (BPMN) have been used to model existing GS products and the procedures GS engineers use to produce them.

  18. NANODUST DETECTION BETWEEN 1 AND 5 AU USING CASSINI WAVE MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Schippers, P.; Vernet, N. Meyer-; Lecacheux, A.; Belheouane, S.; Moncuquet, M. [LESIA—CNRS—Observatoire de Paris, 5 place Jules Janssen, F-92195 Meudon (France); Kurth, W. S. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA (United States); Mann, I. [EISCAT Scientific Association, Kiruna, Sweden and Department of Physics Umeå University (Sweden); Mitchell, D. G. [Applied Physics Laboratory, John Hopkins University, Laurel, MD (United States); André, N. [IRAP, 9 Avenue du Colonel Roche, F-31028 Toulouse (France)

    2015-06-10

    The solar system contains solids of all sizes, ranging from kilometer-sized bodies to nano-sized particles. Nanograins have been detected in situ in the Earth's atmosphere, near cometary and giant planet environments, and more recently in the solar wind at 1 AU. The latter nanograins are thought to be formed in the inner solar system dust cloud, mainly through the collisional break-up of larger grains, and are then picked up and accelerated by the magnetized solar wind because of their large charge-to-mass ratio. In the present paper, we analyze the low frequency bursty noise identified in the Cassini radio and plasma wave data during the spacecraft cruise phase inside Jupiter's orbit. The magnitude, spectral shape, and waveform of this broadband noise are consistent with the signatures of the nano particles that traveled at solar wind speed and impinged on the spacecraft surface. Nanoparticles were observed whenever the radio instrument was turned on and able to detect them at different heliocentric distances between Earth and Jupiter, suggesting their ubiquitous presence in the heliosphere. We analyzed the radial dependence of the nanodust flux with heliospheric distance and found that it is consistent with the dynamics of nanodust originating from the inner heliosphere and picked up by the solar wind. The contribution of the nanodust produced in the asteroid belt appears to be negligible compared to the trapping region in the inner heliosphere. In contrast, further out, nanodust is mainly produced by the volcanism of active moons such as Io and Enceladus.

  19. Numerical Modelling Approaches for Sediment Transport in Sewer Systems

    DEFF Research Database (Denmark)

    Mark, Ole

    A study of the sediment transport processes in sewers has been carried out. Based on this study a mathematical modelling system has been developed to describe the transport processes of sediments and dissolved matter in sewer systems. The modelling system consists of three sub-models which...... constitute the basic modelling system necessary to give a discription of the most dominant physical transport processes concerning particles and dissolved matter in sewer systems: A surface model. An advection-dispersion model. A sediment transport model....

  20. Stochastic Modelling Of The Repairable System

    Directory of Open Access Journals (Sweden)

    Andrzejczak Karol

    2015-11-01

    Full Text Available All reliability models consisting of random time factors form stochastic processes. In this paper we recall the definitions of the most common point processes which are used for modelling of repairable systems. Particularly this paper presents stochastic processes as examples of reliability systems for the support of the maintenance related decisions. We consider the simplest one-unit system with a negligible repair or replacement time, i.e., the unit is operating and is repaired or replaced at failure, where the time required for repair and replacement is negligible. When the repair or replacement is completed, the unit becomes as good as new and resumes operation. The stochastic modelling of recoverable systems constitutes an excellent method of supporting maintenance related decision-making processes and enables their more rational use.

  1. Agent oriented modeling of business information systems

    OpenAIRE

    Vymetal, Dominik

    2009-01-01

    Enterprise modeling is an abstract definition of processes running in enterprise using process, value, data and resource models. There are two perspectives of business modeling: process perspective and value chain perspective. Both have some advantages and disadvantages. This paper proposes a combination of both perspectives into one generic model. The model takes also social part or the enterprise system into consideration and pays attention to disturbances influencing the enterprise system....

  2. Learning Markov models for stationary system behaviors

    DEFF Research Database (Denmark)

    Chen, Yingke; Mao, Hua; Jaeger, Manfred

    2012-01-01

    to a single long observation sequence, and in these situations existing automatic learning methods cannot be applied. In this paper, we adapt algorithms for learning variable order Markov chains from a single observation sequence of a target system, so that stationary system properties can be verified using......Establishing an accurate model for formal verification of an existing hardware or software system is often a manual process that is both time consuming and resource demanding. In order to ease the model construction phase, methods have recently been proposed for automatically learning accurate...... the learned model. Experiments demonstrate that system properties (formulated as stationary probabilities of LTL formulas) can be reliably identified using the learned model....

  3. Modelling and Verification of Relay Interlocking Systems

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth; Bliguet, Marie Le; Kjær, Andreas

    2010-01-01

    This paper describes how relay interlocking systems as used by the Danish railways can be formally modelled and verified. Such systems are documented by circuit diagrams describing their static layout. It is explained how to derive a state transition system model for the dynamic behaviour...

  4. Economic model of pipeline transportation systems

    Energy Technology Data Exchange (ETDEWEB)

    Banks, W. F.

    1977-07-29

    The objective of the work reported here was to develop a model which could be used to assess the economic effects of energy-conservative technological innovations upon the pipeline industry. The model is a dynamic simulator which accepts inputs of two classes: the physical description (design parameters, fluid properties, and financial structures) of the system to be studied, and the postulated market (throughput and price) projection. The model consists of time-independent submodels: the fluidics model which simulates the physical behavior of the system, and the financial model which operates upon the output of the fluidics model to calculate the economics outputs. Any of a number of existing fluidics models can be used in addition to that developed as a part of this study. The financial model, known as the Systems, Science and Software (S/sup 3/) Financial Projection Model, contains user options whereby pipeline-peculiar characteristics can be removed and/or modified, so that the model can be applied to virtually any kind of business enterprise. The several dozen outputs are of two classes: the energetics and the economics. The energetics outputs of primary interest are the energy intensity, also called unit energy consumption, and the total energy consumed. The primary economics outputs are the long-run average cost, profit, cash flow, and return on investment.

  5. PRESSURE EQUILIBRIUM BETWEEN THE LOCAL INTERSTELLAR CLOUDS AND THE LOCAL HOT BUBBLE

    Energy Technology Data Exchange (ETDEWEB)

    Snowden, S. L.; Chiao, M.; Collier, M. R.; Porter, F. S.; Thomas, N. E. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Cravens, T.; Robertson, I. P. [Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045 (United States); Galeazzi, M.; Uprety, Y.; Ursino, E. [Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, FL 33146 (United States); Koutroumpa, D. [Université Versailles St-Quentin, Sorbonne Universités, UPMC Univ. Paris 06, CNRS/INSU, LATMOS-IPSL, 11 Boulevard d' Alembert, F-78280 Guyancourt (France); Kuntz, K. D. [The Henry A. Rowland Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Lallement, R.; Puspitarini, L. [GEPI, Observatoire de Paris, CNRS UMR8111, Université Paris Diderot, 5 Place Jules Janssen, F-92190 Meudon (France); Lepri, S. T. [University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States); McCammon, D.; Morgan, K. [Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, WI 53706 (United States); Walsh, B. M., E-mail: steven.l.snowden@nasa.gov [Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 94720 (United States)

    2014-08-10

    Three recent results related to the heliosphere and the local interstellar medium (ISM) have provided an improved insight into the distribution and conditions of material in the solar neighborhood. These are the measurement of the magnetic field outside of the heliosphere by Voyager 1, the improved mapping of the three-dimensional structure of neutral material surrounding the Local Cavity using extensive ISM absorption line and reddening data, and a sounding rocket flight which observed the heliospheric helium focusing cone in X-rays and provided a robust estimate of the contribution of solar wind charge exchange emission to the ROSAT All-Sky Survey 1/4 keV band data. Combining these disparate results, we show that the thermal pressure of the plasma in the Local Hot Bubble (LHB) is P/k = 10, 700 cm{sup –3} K. If the LHB is relatively free of a global magnetic field, it can easily be in pressure (thermal plus magnetic field) equilibrium with the local interstellar clouds, eliminating a long-standing discrepancy in models of the local ISM.

  6. Deciphering the Local Interstellar Spectra of Primary Cosmic-Ray Species with HELMOD

    Science.gov (United States)

    Boschini, M. J.; Della Torre, S.; Gervasi, M.; Grandi, D.; Jóhannesson, G.; La Vacca, G.; Masi, N.; Moskalenko, I. V.; Pensotti, S.; Porter, T. A.; Quadrani, L.; Rancoita, P. G.; Rozza, D.; Tacconi, M.

    2018-05-01

    Local interstellar spectra (LIS) of primary cosmic ray (CR) nuclei, such as helium, oxygen, and mostly primary carbon are derived for the rigidity range from 10 MV to ∼200 TV using the most recent experimental results combined with the state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. Two propagation packages, GALPROP and HELMOD, are combined into a single framework that is used to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. The developed iterative maximum-likelihood method uses GALPROP-predicted LIS as input to HELMOD, which provides the modulated spectra for specific time periods of the selected experiments for model–data comparison. The interstellar and heliospheric propagation parameters derived in this study are consistent with our prior analyses using the same methodology for propagation of CR protons, helium, antiprotons, and electrons. The resulting LIS accommodate a variety of measurements made in the local interstellar space (Voyager 1) and deep inside the heliosphere at low (ACE/CRIS, HEAO-3) and high energies (PAMELA, AMS-02).

  7. Combining multimedia models with integrated urban water system models for micropollutants

    DEFF Research Database (Denmark)

    De Keyser, W.; Gevaert, V.; Verdonck, F.

    2009-01-01

    Integrated urban water system (IUWS) modelling aims at assessing the quality of the surface water receiving the urban emissions through sewage treatment plants, combined sewer overflows (CSOs) and stormwater drainage systems. However, some micropollutants have the tendency to occur in more than one...... environmental medium. In this work, a multimedia fate and transport model (MFTM) is “wrapped around” a dynamic IUWS model for organic micropollutants to enable integrated environmental assessment. The combined model was tested on a hypothetical catchment using two scenarios: a reference scenario...... and a stormwater infiltration pond scenario, as an example of a sustainable urban drainage system (SUDS). A case for Bis(2-ethylhexyl) phthalate (DEHP) was simulated and resulted in a reduced surface water concentration for the latter scenario. However, the model also showed that this was at the expense...

  8. Automated statistical modeling of analytical measurement systems

    International Nuclear Information System (INIS)

    Jacobson, J.J.

    1992-01-01

    The statistical modeling of analytical measurement systems at the Idaho Chemical Processing Plant (ICPP) has been completely automated through computer software. The statistical modeling of analytical measurement systems is one part of a complete quality control program used by the Remote Analytical Laboratory (RAL) at the ICPP. The quality control program is an integration of automated data input, measurement system calibration, database management, and statistical process control. The quality control program and statistical modeling program meet the guidelines set forth by the American Society for Testing Materials and American National Standards Institute. A statistical model is a set of mathematical equations describing any systematic bias inherent in a measurement system and the precision of a measurement system. A statistical model is developed from data generated from the analysis of control standards. Control standards are samples which are made up at precise known levels by an independent laboratory and submitted to the RAL. The RAL analysts who process control standards do not know the values of those control standards. The object behind statistical modeling is to describe real process samples in terms of their bias and precision and, to verify that a measurement system is operating satisfactorily. The processing of control standards gives us this ability

  9. Design theoretic analysis of three system modeling frameworks.

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Michael James

    2007-05-01

    This paper analyzes three simulation architectures from the context of modeling scalability to address System of System (SoS) and Complex System problems. The paper first provides an overview of the SoS problem domain and reviews past work in analyzing model and general system complexity issues. It then identifies and explores the issues of vertical and horizontal integration as well as coupling and hierarchical decomposition as the system characteristics and metrics against which the tools are evaluated. In addition, it applies Nam Suh's Axiomatic Design theory as a construct for understanding coupling and its relationship to system feasibility. Next it describes the application of MATLAB, Swarm, and Umbra (three modeling and simulation approaches) to modeling swarms of Unmanned Flying Vehicle (UAV) agents in relation to the chosen characteristics and metrics. Finally, it draws general conclusions for analyzing model architectures that go beyond those analyzed. In particular, it identifies decomposition along phenomena of interaction and modular system composition as enabling features for modeling large heterogeneous complex systems.

  10. An L-system model for root system mycorrhization

    Science.gov (United States)

    Schnepf, Andrea; Schweiger, Peter; Jansa, Jan; Leitner, Daniel

    2014-05-01

    Mineral phosphate fertilisers are a non-renewable resource; rock phosphate reserves are estimated to be depleted in 50 to 100 years. In order to prevent a severe phosphate crisis in the 21st century, there is a need to decrease agricultural inputs such as P fertilisers by making use of plant mechanisms that increase P acquisition efficiency. Most plants establish mycorrhizal symbiosis as an adaptation to increase/economize their P acquisition from the soil. However, there is a great functional diversity in P acquisition mechanisms among different fungal species that colonize the roots (Thonar et al. 2011), and the composition of mycorrhizal community is known to depend strongly on agricultural management practices. Thus, the agroecosystem management may substantially affect the mycorrhizal functioning and also the use of P fertilizers. To date, it is still difficult to quantify the potential input savings for the agricultural crops through manipulation of their symbiotic microbiome, mainly due to lack of mechanistic understanding of P uptake dynamics by the fungal hyphae. In a first attempt, Schnepf et al. (2008b) have used mathematical modelling to show on the single root scale how different fungal growth pattern influence root P uptake. However, their approach was limited by the fact that it was restricted to the scale of a single root. The goal of this work is to advance the dynamic, three-dimensional root architecture model of Leitner et al. (2010) to include root system infection with arbuscular mycorrhizal fungi and growth of external mycelium. The root system infection model assumes that there is an average probability of infection (primary infection), that the probability of infection of a new root segment immediately adjacent to an existing infection is much higher than the average (secondary infection), that infected root segments have entry points that are the link between internal and external mycelium, that only uninfected root segments are susceptible

  11. Spatial Models and Networks of Living Systems

    DEFF Research Database (Denmark)

    Juul, Jeppe Søgaard

    When studying the dynamics of living systems, insight can often be gained by developing a mathematical model that can predict future behaviour of the system or help classify system characteristics. However, in living cells, organisms, and especially groups of interacting individuals, a large number...... variables of the system. However, this approach disregards any spatial structure of the system, which may potentially change the behaviour drastically. An alternative approach is to construct a cellular automaton with nearest neighbour interactions, or even to model the system as a complex network...... with interactions defined by network topology. In this thesis I first describe three different biological models of ageing and cancer, in which spatial structure is important for the system dynamics. I then turn to describe characteristics of ecosystems consisting of three cyclically interacting species...

  12. System and circuit models for microwave antennas

    OpenAIRE

    Sobhy, Mohammed; Sanz-Izquierdo, Benito; Batchelor, John C.

    2007-01-01

    This paper describes how circuit and system models are derived for antennas from measurement of the input reflection coefficient. Circuit models are used to optimize the antenna performance and to calculate the radiated power and the transfer function of the antenna. System models are then derived for transmitting and receiving antennas. The most important contribution of this study is to show how microwave structures can be integrated into the simulation of digital communication systems. Thi...

  13. Engineered Barrier System: Physical and Chemical Environment Model

    International Nuclear Information System (INIS)

    Jolley, D. M.; Jarek, R.; Mariner, P.

    2004-01-01

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports

  14. Using Difference Equation to Model Discrete-time Behavior in System Dynamics Modeling

    NARCIS (Netherlands)

    Hesan, R.; Ghorbani, A.; Dignum, M.V.

    2014-01-01

    In system dynamics modeling, differential equations have been used as the basic mathematical operator. Using difference equation to build system dynamics models instead of differential equation, can be insightful for studying small organizations or systems with micro behavior. In this paper we

  15. The FEL-TNO uniform open systems model

    NARCIS (Netherlands)

    Luiijf, H.A.M.; Overbeek, P.L.

    1989-01-01

    The FEL-TNO Uniform Open Systems Model is based upon the IS0/0SI Basic Reference Model and integrates operating systems, (OSI) networks, equipment and media into one single uniform nodel. Usage of the model stimulates the development of operating systen and network independent applications and puts

  16. Intrinsic Uncertainties in Modeling Complex Systems.

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Curtis S; Bramson, Aaron L.; Ames, Arlo L.

    2014-09-01

    Models are built to understand and predict the behaviors of both natural and artificial systems. Because it is always necessary to abstract away aspects of any non-trivial system being modeled, we know models can potentially leave out important, even critical elements. This reality of the modeling enterprise forces us to consider the prospective impacts of those effects completely left out of a model - either intentionally or unconsidered. Insensitivity to new structure is an indication of diminishing returns. In this work, we represent a hypothetical unknown effect on a validated model as a finite perturba- tion whose amplitude is constrained within a control region. We find robustly that without further constraints, no meaningful bounds can be placed on the amplitude of a perturbation outside of the control region. Thus, forecasting into unsampled regions is a very risky proposition. We also present inherent difficulties with proper time discretization of models and representing in- herently discrete quantities. We point out potentially worrisome uncertainties, arising from math- ematical formulation alone, which modelers can inadvertently introduce into models of complex systems. Acknowledgements This work has been funded under early-career LDRD project #170979, entitled "Quantify- ing Confidence in Complex Systems Models Having Structural Uncertainties", which ran from 04/2013 to 09/2014. We wish to express our gratitude to the many researchers at Sandia who con- tributed ideas to this work, as well as feedback on the manuscript. In particular, we would like to mention George Barr, Alexander Outkin, Walt Beyeler, Eric Vugrin, and Laura Swiler for provid- ing invaluable advice and guidance through the course of the project. We would also like to thank Steven Kleban, Amanda Gonzales, Trevor Manzanares, and Sarah Burwell for their assistance in managing project tasks and resources.

  17. Modeling of nonlinear biological phenomena modeled by S-systems.

    Science.gov (United States)

    Mansouri, Majdi M; Nounou, Hazem N; Nounou, Mohamed N; Datta, Aniruddha A

    2014-03-01

    A central challenge in computational modeling of biological systems is the determination of the model parameters. In such cases, estimating these variables or parameters from other easily obtained measurements can be extremely useful. For example, time-series dynamic genomic data can be used to develop models representing dynamic genetic regulatory networks, which can be used to design intervention strategies to cure major diseases and to better understand the behavior of biological systems. Unfortunately, biological measurements are usually highly infected by errors that hide the important characteristics in the data. Therefore, these noisy measurements need to be filtered to enhance their usefulness in practice. This paper addresses the problem of state and parameter estimation of biological phenomena modeled by S-systems using Bayesian approaches, where the nonlinear observed system is assumed to progress according to a probabilistic state space model. The performances of various conventional and state-of-the-art state estimation techniques are compared. These techniques include the extended Kalman filter (EKF), unscented Kalman filter (UKF), particle filter (PF), and the developed variational Bayesian filter (VBF). Specifically, two comparative studies are performed. In the first comparative study, the state variables (the enzyme CadA, the model cadBA, the cadaverine Cadav and the lysine Lys for a model of the Cad System in Escherichia coli (CSEC)) are estimated from noisy measurements of these variables, and the various estimation techniques are compared by computing the estimation root mean square error (RMSE) with respect to the noise-free data. In the second comparative study, the state variables as well as the model parameters are simultaneously estimated. In this case, in addition to comparing the performances of the various state estimation techniques, the effect of the number of estimated model parameters on the accuracy and convergence of these

  18. Microphysics in Multi-scale Modeling System with Unified Physics

    Science.gov (United States)

    Tao, Wei-Kuo

    2012-01-01

    Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model), (2) a regional scale model (a NASA unified weather research and forecast, WRF), (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF), and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation, and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, a review of developments and applications of the multi-scale modeling system will be presented. In particular, the microphysics development and its performance for the multi-scale modeling system will be presented.

  19. Mathematical Modeling of Hybrid Electrical Engineering Systems

    Directory of Open Access Journals (Sweden)

    A. A. Lobaty

    2016-01-01

    Full Text Available A large class of systems that have found application in various industries and households, electrified transportation facilities and energy sector has been classified as electrical engineering systems. Their characteristic feature is a combination of continuous and discontinuous modes of operation, which is reflected in the appearance of a relatively new term “hybrid systems”. A wide class of hybrid systems is pulsed DC converters operating in a pulse width modulation, which are non-linear systems with variable structure. Using various methods for linearization it is possible to obtain linear mathematical models that rather accurately simulate behavior of such systems. However, the presence in the mathematical models of exponential nonlinearities creates considerable difficulties in the implementation of digital hardware. The solution can be found while using an approximation of exponential functions by polynomials of the first order, that, however, violates the rigor accordance of the analytical model with characteristics of a real object. There are two practical approaches to synthesize algorithms for control of hybrid systems. The first approach is based on the representation of the whole system by a discrete model which is described by difference equations that makes it possible to synthesize discrete algorithms. The second approach is based on description of the system by differential equations. The equations describe synthesis of continuous algorithms and their further implementation in a digital computer included in the control loop system. The paper considers modeling of a hybrid electrical engineering system using differential equations. Neglecting the pulse duration, it has been proposed to describe behavior of vector components in phase coordinates of the hybrid system by stochastic differential equations containing generally non-linear differentiable random functions. A stochastic vector-matrix equation describing dynamics of the

  20. CTBT integrated verification system evaluation model supplement

    International Nuclear Information System (INIS)

    EDENBURN, MICHAEL W.; BUNTING, MARCUS; PAYNE, ARTHUR C. JR.; TROST, LAWRENCE C.

    2000-01-01

    Sandia National Laboratories has developed a computer based model called IVSEM (Integrated Verification System Evaluation Model) to estimate the performance of a nuclear detonation monitoring system. The IVSEM project was initiated in June 1994, by Sandia's Monitoring Systems and Technology Center and has been funded by the U.S. Department of Energy's Office of Nonproliferation and National Security (DOE/NN). IVSEM is a simple, ''top-level,'' modeling tool which estimates the performance of a Comprehensive Nuclear Test Ban Treaty (CTBT) monitoring system and can help explore the impact of various sensor system concepts and technology advancements on CTBT monitoring. One of IVSEM's unique features is that it integrates results from the various CTBT sensor technologies (seismic, in sound, radionuclide, and hydroacoustic) and allows the user to investigate synergy among the technologies. Specifically, IVSEM estimates the detection effectiveness (probability of detection), location accuracy, and identification capability of the integrated system and of each technology subsystem individually. The model attempts to accurately estimate the monitoring system's performance at medium interfaces (air-land, air-water) and for some evasive testing methods such as seismic decoupling. The original IVSEM report, CTBT Integrated Verification System Evaluation Model, SAND97-25 18, described version 1.2 of IVSEM. This report describes the changes made to IVSEM version 1.2 and the addition of identification capability estimates that have been incorporated into IVSEM version 2.0

  1. A distributed snow-evolution modeling system (SnowModel)

    Science.gov (United States)

    Glen E. Liston; Kelly. Elder

    2006-01-01

    SnowModel is a spatially distributed snow-evolution modeling system designed for application in landscapes, climates, and conditions where snow occurs. It is an aggregation of four submodels: MicroMet defines meteorological forcing conditions, EnBal calculates surface energy exchanges, SnowPack simulates snow depth and water-equivalent evolution, and SnowTran-3D...

  2. Challenges in Modeling the Sun-Earth System

    Science.gov (United States)

    Spann, James

    2004-01-01

    The transfer of mass, energy and momentum through the coupled Sun-Earth system spans a wide range of scales in time and space. While profound advances have been made in modeling isolated regions of the Sun-Earth system, minimal progress has been achieved in modeling the end-to-end system. Currently, end-to-end modeling of the Sun-Earth system is a major goal of the National Space Weather and NASA Living With a Star (LWS) programs. The uncertainty in the underlying physics responsible for coupling contiguous regions of the Sun-Earth system is recognized as a significant barrier to progress. Our limited understanding of the underlying coupling physics is illustrated by the following example questions: how does the propagation of a typical CME/solar flare influence the measured properties of the solar wind at 1 AU? How does the solar wind compel the dynamic response of the Earth's magnetosphere? How is variability in the ionosphere-thermosphere system coupled to magnetospheric variations? Why do these and related important questions remain unanswered? What are the primary problems that need to be resolved to enable significant progress in comprehensive modeling of the Sun-Earth system? Which model/technique improvements are required and what new data coverage is required to enable full model advances? This poster opens the discussion for how these and other important questions can be addressed. A workshop scheduled for October 8-22, 2004 in Huntsville, Alabama, will be a forum for identifying ana exploring promising new directions and approaches for characterizing and understanding the system. To focus the discussion, the workshop will emphasize the genesis, evolution, propagation and interaction of high-speed solar wind streamers or CME/flares with geospace and the subsequent response of geospace from its outer reaches in the magnetosphere to the lower edge of the ionosphere-mesosphere-thermosphere. Particular emphasis will be placed on modeling the coupling aspects

  3. System of systems dependability – Theoretical models and applications examples

    International Nuclear Information System (INIS)

    Bukowski, L.

    2016-01-01

    The aim of this article is to generalise the concept of 'dependability' in a way, that could be applied to all types of systems, especially the system of systems (SoS), operating under both normal and abnormal work conditions. In order to quantitatively assess the dependability we applied service continuity oriented approach. This approach is based on the methodology of service engineering and is closely related to the idea of resilient enterprise as well as to the concept of disruption-tolerant operation. On this basis a framework for evaluation of SoS dependability has been developed in a static as well as dynamic approach. The static model is created as a fuzzy logic-oriented advisory expert system and can be particularly useful at the design stage of SoS. The dynamic model is based on the risk oriented approach, and can be useful both at the design stage and for management of SoS. The integrated model of dependability can also form the basis for a new definition of the dependability engineering, namely as a superior discipline to reliability engineering, safety engineering, security engineering, resilience engineering and risk engineering. - Highlights: • A framework for evaluation of system of systems dependability is presented. • The model is based on the service continuity concept and consists of two parts. • The static part can be created as a fuzzy logic-oriented advisory expert system. • The dynamic, risk oriented part, is related to the concept of throughput chain. • A new definition of dependability engineering is proposed.

  4. Developing a Model of the Irish Energy-System

    DEFF Research Database (Denmark)

    Connolly, David; Lund, Henrik; Mathiesen, Brian Vad

    2009-01-01

    to create the model as it accounts for all sectors that need to be considered for integrating large penetrations of renewable energy: the electricity, heat and transport sectors. Before various alternative energy-systems could be investigated for Ireland, a reference model of the existing system needed...... is a vital step due to the scale of the change required for large-scale renewable penetrations. In this paper, a model of the Irish energy system is created to identify how Ireland can transform from a fossil-fuel to a renewable energy-system. The energy-systems-analysis tool, EnergyPLAN, was chosen...... to be created. This paper focuses on the construction of this reference model, in terms of the data gathered, the assumptions made and the accuracy achieved. In future work, this model will be used to investigate alternative energy-systems for Ireland, with the aim to determine the most effective energy system...

  5. Hybrid simulation models for data-intensive systems

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00473067

    Data-intensive systems are used to access and store massive amounts of data by combining the storage resources of multiple data-centers, usually deployed all over the world, in one system. This enables users to utilize these massive storage capabilities in a simple and efficient way. However, with the growth of these systems it becomes a hard problem to estimate the effects of modifications to the system, such as data placement algorithms or hardware upgrades, and to validate these changes for potential side effects. This thesis addresses the modeling of operational data-intensive systems and presents a novel simulation model which estimates the performance of system operations. The running example used throughout this thesis is the data-intensive system Rucio, which is used as the data man- agement system of the ATLAS experiment at CERN’s Large Hadron Collider. Existing system models in literature are not applicable to data-intensive workflows, as they only consider computational workflows or make assumpti...

  6. Modeling of battery energy storage in the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    Swaminathan, S.; Flynn, W.T.; Sen, R.K. [Sentech, Inc., Bethesda, MD (United States)

    1997-12-01

    The National Energy Modeling System (NEMS) developed by the U.S. Department of Energy`s Energy Information Administration is a well-recognized model that is used to project the potential impact of new electric generation technologies. The NEMS model does not presently have the capability to model energy storage on the national grid. The scope of this study was to assess the feasibility of, and make recommendations for, the modeling of battery energy storage systems in the Electricity Market of the NEMS. Incorporating storage within the NEMS will allow the national benefits of storage technologies to be evaluated.

  7. THE INTERSTELLAR MEDIUM IN THE KEPLER SEARCH VOLUME

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Marshall C. [Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712 (United States); Redfield, Seth [Astronomy Department, Van Vleck Observatory, Wesleyan University, Middletown, CT 06459 (United States); Jensen, Adam G., E-mail: mjohnson@astro.as.utexas.edu [Department of Physics and Physical Science, University of Nebraska-Kearney, Bruner Hall of Science, 2401 11th Ave, Kearney, NE 68849 (United States)

    2015-07-10

    The properties of the interstellar medium (ISM) surrounding a planetary system can impact planetary climate through a number of mechanisms, including changing the size of the astrosphere (one of the major shields for cosmic rays) as well as direct deposition of material into planetary atmospheres. In order to constrain the ambient ISM conditions for exoplanetary systems, we present observations of interstellar Na i and K i absorption toward seventeen early type stars in the Kepler prime mission field of view (FOV). We identify 39 Na i and 8 K i velocity components, and attribute these to 11 ISM clouds. Six of these are detected toward more than one star, and for these clouds we put limits on the cloud properties, including distance and hydrogen number density. We identify one cloud with significant (≳1.5 cm{sup −3}) hydrogen number density located within the nominal ∼100 pc boundary of the Local Bubble. We identify systems with confirmed planets within the Kepler FOV that could lie within these ISM clouds, and estimate upper limits on the astrosphere sizes of these systems under the assumption that they do lie within these clouds. Under this condition, the Kepler-20, 42, and 445 multiplanet systems could have compressed astrospheres much smaller than the present-day heliosphere. Among the known habitable zone planet hosts, Kepler-186 could have an astrosphere somewhat smaller than the heliosphere, while Kepler-437 and KOI-4427 could have astrospheres much larger than the heliosphere. The thick disk star Kepler-444 may have an astrosphere just a few AU in radius.

  8. Engineered Barrier System: Physical and Chemical Environment Model

    Energy Technology Data Exchange (ETDEWEB)

    D. M. Jolley; R. Jarek; P. Mariner

    2004-02-09

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.

  9. Solar Energetic Particle Composition over Two Solar Cycles as Observed by the Ulysses/HISCALE and ACE/EPAM Pulse Height Analyzers.

    Science.gov (United States)

    Patterson, J. D.; Madanian, H.; Manweiler, J. W.; Lanzerotti, L. J.

    2017-12-01

    We present the compositional variation in the Solar Energetic Particle (SEP) population in the inner heliosphere over two solar cycles using data from the Ulysses Heliospheric Instrument for Spectra, Composition, and Anisotropy at Low Energies (HISCALE) and Advanced Composition Explorer (ACE) Electron Proton Alpha Monitor (EPAM). The Ulysses mission was active from late 1990 to mid-2009 in a heliopolar orbit inclined by 80° with a perihelion of 1.3 AU and an aphelion of 5.4 AU. The ACE mission has been active since its launch in late 1997 and is in a halo orbit about L1. These two missions provide a total of 27 years of continuous observation in the inner heliosphere with twelve years of simultaneous observation. HISCALE and EPAM data provide species-resolved differential flux and density of SEP between 0.5-5 MeV/nuc. Several ion species (He, C, O, Ne, Si, Fe) are identified using the Pulse Height Analyzer (PHA) system of the Composition Aperture for both instruments. The He density shows a noticeable increase at high solar activity followed by a moderate drop at the quiet time of the solar minimum between cycles 23 and 24. The density of heavier ions (i.e. O and Fe) change minimally with respect to the F10.7 index variations however, certain energy-specific count rates decrease during solar minimum. With Ulysses and ACE observing in different regions of the inner heliosphere, there are significant latitudinal differences in how the O/He ratios vary with the solar cycle. At solar minimum, there is reasonable agreement between the observations from both instruments. At solar max 23, the differences in composition over the course of the solar cycle, and as observed at different heliospheric locations can provide insight to the origins of and acceleration processes differentially affecting solar energetic ions.

  10. Models for a stand-alone PV system

    DEFF Research Database (Denmark)

    Hansen, A.D.; Sørensen, Poul Ejnar; Hansen, L.H.

    2001-01-01

    are based on the model descriptions found in the literature. The battery model is developed at UMASS and is known as the Kinetic Battery Model(KiBaM). The other component models in the PV system are based on simple electrical knowledge. The implementation is done using Matlab/Simulink, a simulation program......This report presents a number of models for modelling and simulation of a stand-alone photovoltaic (PV) system with a battery bank verified against a system installed at Risø National Laboratory. The work has been supported by the Danish Ministry ofEnergy, as a part of the activities in the Solar...... Energy Centre Denmark. The study is carried out at Risø National Laboratory with the main purpose to establish a library of simple mathematical models for each individual element of a stand-alone PVsystem, namely solar cells, battery, controller, inverter and load. The models for PV module and battery...

  11. On domain modelling of the service system with its application to enterprise information systems

    Science.gov (United States)

    Wang, J. W.; Wang, H. F.; Ding, J. L.; Furuta, K.; Kanno, T.; Ip, W. H.; Zhang, W. J.

    2016-01-01

    Information systems are a kind of service systems and they are throughout every element of a modern industrial and business system, much like blood in our body. Types of information systems are heterogeneous because of extreme uncertainty in changes in modern industrial and business systems. To effectively manage information systems, modelling of the work domain (or domain) of information systems is necessary. In this paper, a domain modelling framework for the service system is proposed and its application to the enterprise information system is outlined. The framework is defined based on application of a general domain modelling tool called function-context-behaviour-principle-state-structure (FCBPSS). The FCBPSS is based on a set of core concepts, namely: function, context, behaviour, principle, state and structure and system decomposition. Different from many other applications of FCBPSS in systems engineering, the FCBPSS is applied to both infrastructure and substance systems, which is novel and effective to modelling of service systems including enterprise information systems. It is to be noted that domain modelling of systems (e.g. enterprise information systems) is a key to integration of heterogeneous systems and to coping with unanticipated situations facing to systems.

  12. Comets as a possible source of nanodust in the Solar System cloud and in planetary debris discs.

    Science.gov (United States)

    Mann, Ingrid

    2017-07-13

    Comets, comet-like objects and their fragments are the most plausible source for the dust in both the inner heliosphere and planetary debris discs around other stars. The smallest size of dust particles in debris discs is not known and recent observational results suggest that the size distribution of the dust extends down to sizes of a few nanometres or a few tens of nanometres. In the Solar System, electric field measurements from spacecraft observe events that are explained with high-velocity impacts of nanometre-sized dust. In some planetary debris discs an observed mid- to near-infrared emission supposedly results from hot dust located in the vicinity of the star. And the observed emission is characteristic of dust of sizes a few tens of nanometres. Rosetta observations, on the other hand, provide little information on the presence of nanodust near comet 67P/Churyumov-Gerasimenko. This article describes why this is not in contradiction to the observations of nanodust in the heliosphere and in planetary debris discs. The direct ejection of nanodust from the nucleus of the comet would not contribute significantly to the observed nanodust fluxes. We discuss a scenario that nanodust forms in the interplanetary dust cloud through the high-velocity collision process in the interplanetary medium for which the production rates are highest near the Sun. Likewise, fragmentation by collisions occurs near the star in planetary debris discs. The collisional fragmentation process in the inner Solar System occurs at similar velocities to those of the collisional evolution in the interstellar medium. A question for future studies is whether there is a common magic size of the smallest collision fragments and what determines this size.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Author(s).

  13. Modelling and control of dynamic systems using gaussian process models

    CERN Document Server

    Kocijan, Juš

    2016-01-01

    This monograph opens up new horizons for engineers and researchers in academia and in industry dealing with or interested in new developments in the field of system identification and control. It emphasizes guidelines for working solutions and practical advice for their implementation rather than the theoretical background of Gaussian process (GP) models. The book demonstrates the potential of this recent development in probabilistic machine-learning methods and gives the reader an intuitive understanding of the topic. The current state of the art is treated along with possible future directions for research. Systems control design relies on mathematical models and these may be developed from measurement data. This process of system identification, when based on GP models, can play an integral part of control design in data-based control and its description as such is an essential aspect of the text. The background of GP regression is introduced first with system identification and incorporation of prior know...

  14. System Dynamics Modeling for Supply Chain Information Sharing

    Science.gov (United States)

    Feng, Yang

    In this paper, we try to use the method of system dynamics to model supply chain information sharing. Firstly, we determine the model boundaries, establish system dynamics model of supply chain before information sharing, analyze the model's simulation results under different changed parameters and suggest improvement proposal. Then, we establish system dynamics model of supply chain information sharing and make comparison and analysis on the two model's simulation results, to show the importance of information sharing in supply chain management. We wish that all these simulations would provide scientific supports for enterprise decision-making.

  15. Models used to assess the performance of photovoltaic systems.

    Energy Technology Data Exchange (ETDEWEB)

    Stein, Joshua S.; Klise, Geoffrey T.

    2009-12-01

    This report documents the various photovoltaic (PV) performance models and software developed and utilized by researchers at Sandia National Laboratories (SNL) in support of the Photovoltaics and Grid Integration Department. In addition to PV performance models, hybrid system and battery storage models are discussed. A hybrid system using other distributed sources and energy storage can help reduce the variability inherent in PV generation, and due to the complexity of combining multiple generation sources and system loads, these models are invaluable for system design and optimization. Energy storage plays an important role in reducing PV intermittency and battery storage models are used to understand the best configurations and technologies to store PV generated electricity. Other researcher's models used by SNL are discussed including some widely known models that incorporate algorithms developed at SNL. There are other models included in the discussion that are not used by or were not adopted from SNL research but may provide some benefit to researchers working on PV array performance, hybrid system models and energy storage. The paper is organized into three sections to describe the different software models as applied to photovoltaic performance, hybrid systems, and battery storage. For each model, there is a description which includes where to find the model, whether it is currently maintained and any references that may be available. Modeling improvements underway at SNL include quantifying the uncertainty of individual system components, the overall uncertainty in modeled vs. measured results and modeling large PV systems. SNL is also conducting research into the overall reliability of PV systems.

  16. Aerial Measuring System Sensor Modeling

    International Nuclear Information System (INIS)

    Detwiler, R.S.

    2002-01-01

    This project deals with the modeling the Aerial Measuring System (AMS) fixed-wing and rotary-wing sensor systems, which are critical U.S. Department of Energy's National Nuclear Security Administration (NNSA) Consequence Management assets. The fixed-wing system is critical in detecting lost or stolen radiography or medical sources, or mixed fission products as from a commercial power plant release at high flying altitudes. The helicopter is typically used at lower altitudes to determine ground contamination, such as in measuring americium from a plutonium ground dispersal during a cleanup. Since the sensitivity of these instruments as a function of altitude is crucial in estimating detection limits of various ground contaminations and necessary count times, a characterization of their sensitivity as a function of altitude and energy is needed. Experimental data at altitude as well as laboratory benchmarks is important to insure that the strong effects of air attenuation are modeled correctly. The modeling presented here is the first attempt at such a characterization of the equipment for flying altitudes. The sodium iodide (NaI) sensors utilized with these systems were characterized using the Monte Carlo N-Particle code (MCNP) developed at Los Alamos National Laboratory. For the fixed wing system, calculations modeled the spectral response for the 3-element NaI detector pod and High-Purity Germanium (HPGe) detector, in the relevant energy range of 50 keV to 3 MeV. NaI detector responses were simulated for both point and distributed surface sources as a function of gamma energy and flying altitude. For point sources, photopeak efficiencies were calculated for a zero radial distance and an offset equal to the altitude. For distributed sources approximating an infinite plane, gross count efficiencies were calculated and normalized to a uniform surface deposition of 1 microCi/m 2 . The helicopter calculations modeled the transport of americium-241 ( 241 Am) as this is

  17. System dynamics and control with bond graph modeling

    CERN Document Server

    Kypuros, Javier

    2013-01-01

    Part I Dynamic System ModelingIntroduction to System DynamicsIntroductionSystem Decomposition and Model ComplexityMathematical Modeling of Dynamic SystemsAnalysis and Design of Dynamic SystemsControl of Dynamic SystemsDiagrams of Dynamic SystemsA Graph-Centered Approach to ModelingSummaryPracticeExercisesBasic Bond Graph ElementsIntroductionPower and Energy VariablesBasic 1-Port ElementsBasic 2-Ports ElementsJunction ElementsSimple Bond Graph ExamplesSummaryPracticeExercisesBond Graph Synthesis and Equation DerivationIntroductionGeneral GuidelinesMechanical TranslationMechanical RotationElectrical CircuitsHydraulic CircuitsMixed SystemsState Equation DerivationState-Space RepresentationsAlgebraic Loops and Derivative CausalitySummaryPracticeExercisesImpedance Bond GraphsIntroductionLaplace Transform of the State-Space EquationBasic 1-Port ImpedancesImpedance Bond Graph SynthesisJunctions, Transformers, and GyratorsEffort and Flow DividersSign ChangesTransfer Function DerivationAlternative Derivation of Transf...

  18. Experimental Modeling of Dynamic Systems

    DEFF Research Database (Denmark)

    Knudsen, Morten Haack

    2006-01-01

    An engineering course, Simulation and Experimental Modeling, has been developed that is based on a method for direct estimation of physical parameters in dynamic systems. Compared with classical system identification, the method appears to be easier to understand, apply, and combine with physical...

  19. Heliopause Electrostatic Rapid Transit System (HERTS)

    Science.gov (United States)

    Wiegmann, Bruce M.

    2015-01-01

    A recent six month investigation focused on: "Determining the benefits of propelling a scientific spacecraft by an 'Electric Sail' propulsion system to the edge of our solar system (the Heliopause), a distance of 100 to 120 AU, in ten years or less" has recently been completed by the Advance Concepts Office at NASA's MSFC. The concept investigated has been named the Heliopause Electrostatic Rapid Transit System (HERTS) by the MSFC team. The HERTS is a revolutionary propellant-less propulsion concept that is ideal for deep space missions to the Outer Planets, Heliopause, and beyond. It is unique in that it uses momentum exchange from naturally occurring solar wind protons to propel a spacecraft within the heliosphere. The propulsion system consists of an array of electrically positively-biased wires that extend outward 20 km from a rotating (one revolution per hour) spacecraft. It was determined that the HERTS system can accelerate a spacecraft to velocities as much as two to three times that possible by any realistic extrapolation of current state-of-the-art propulsion technologies- including solar electric and solar sail propulsion systems. The data produced show that a scientific spacecraft could reach distances of 100AU in less than 10 years. Moreover, it can be reasonably expected that this system could be developed within a decade and provide meaningful Heliophysics Science and Outer Planetary Science returns in the 2025-2035 timeframe.

  20. SMALL-SCALE MAGNETIC ISLANDS IN THE SOLAR WIND AND THEIR ROLE IN PARTICLE ACCELERATION. I. DYNAMICS OF MAGNETIC ISLANDS NEAR THE HELIOSPHERIC CURRENT SHEET

    Energy Technology Data Exchange (ETDEWEB)

    Khabarova, O. [Heliophysical Laboratory, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation RAS (IZMIRAN), Troitsk, Moscow 142190 (Russian Federation); Zank, G. P.; Li, G.; Roux, J. A. le; Webb, G. M.; Dosch, A. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Malandraki, O. E. [IAASARS, National Observatory of Athens, GR-15236 Penteli (Greece)

    2015-08-01

    Increases of ion fluxes in the keV–MeV range are sometimes observed near the heliospheric current sheet (HCS) during periods when other sources are absent. These resemble solar energetic particle events, but the events are weaker and apparently local. Conventional explanations based on either shock acceleration of charged particles or particle acceleration due to magnetic reconnection at interplanetary current sheets (CSs) are not persuasive. We suggest instead that recurrent magnetic reconnection occurs at the HCS and smaller CSs in the solar wind, a consequence of which is particle energization by the dynamically evolving secondary CSs and magnetic islands. The effectiveness of the trapping and acceleration process associated with magnetic islands depends in part on the topology of the HCS. We show that the HCS possesses ripples superimposed on the large-scale flat or wavy structure. We conjecture that the ripples can efficiently confine plasma and provide tokamak-like conditions that are favorable for the appearance of small-scale magnetic islands that merge and/or contract. Particles trapped in the vicinity of merging islands and experiencing multiple small-scale reconnection events are accelerated by the induced electric field and experience first-order Fermi acceleration in contracting magnetic islands according to the transport theory of Zank et al. We present multi-spacecraft observations of magnetic island merging and particle energization in the absence of other sources, providing support for theory and simulations that show particle energization by reconnection related processes of magnetic island merging and contraction.

  1. WSA-Enlil Solar Wind Prediction

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — WSA-Enlil is a large-scale, physics-based prediction model of the heliosphere, used by the Space Weather Forecast Office to provide 1-4 day advance warning of solar...

  2. CTBT integrated verification system evaluation model supplement

    Energy Technology Data Exchange (ETDEWEB)

    EDENBURN,MICHAEL W.; BUNTING,MARCUS; PAYNE JR.,ARTHUR C.; TROST,LAWRENCE C.

    2000-03-02

    Sandia National Laboratories has developed a computer based model called IVSEM (Integrated Verification System Evaluation Model) to estimate the performance of a nuclear detonation monitoring system. The IVSEM project was initiated in June 1994, by Sandia's Monitoring Systems and Technology Center and has been funded by the U.S. Department of Energy's Office of Nonproliferation and National Security (DOE/NN). IVSEM is a simple, ''top-level,'' modeling tool which estimates the performance of a Comprehensive Nuclear Test Ban Treaty (CTBT) monitoring system and can help explore the impact of various sensor system concepts and technology advancements on CTBT monitoring. One of IVSEM's unique features is that it integrates results from the various CTBT sensor technologies (seismic, in sound, radionuclide, and hydroacoustic) and allows the user to investigate synergy among the technologies. Specifically, IVSEM estimates the detection effectiveness (probability of detection), location accuracy, and identification capability of the integrated system and of each technology subsystem individually. The model attempts to accurately estimate the monitoring system's performance at medium interfaces (air-land, air-water) and for some evasive testing methods such as seismic decoupling. The original IVSEM report, CTBT Integrated Verification System Evaluation Model, SAND97-25 18, described version 1.2 of IVSEM. This report describes the changes made to IVSEM version 1.2 and the addition of identification capability estimates that have been incorporated into IVSEM version 2.0.

  3. National Energy Outlook Modelling System

    Energy Technology Data Exchange (ETDEWEB)

    Volkers, C.M. [ECN Policy Studies, Petten (Netherlands)

    2013-12-15

    For over 20 years, the Energy research Centre of the Netherlands (ECN) has been developing the National Energy Outlook Modelling System (NEOMS) for Energy projections and policy evaluations. NEOMS enables 12 energy models of ECN to exchange data and produce consistent and detailed results.

  4. Formal Modeling and Analysis of Timed Systems

    DEFF Research Database (Denmark)

    Larsen, Kim Guldstrand; Niebert, Peter

    This book constitutes the thoroughly refereed post-proceedings of the First International Workshop on Formal Modeling and Analysis of Timed Systems, FORMATS 2003, held in Marseille, France in September 2003. The 19 revised full papers presented together with an invited paper and the abstracts of ...... systems, discrete time systems, timed languages, and real-time operating systems....... of two invited talks were carefully selected from 36 submissions during two rounds of reviewing and improvement. All current aspects of formal method for modeling and analyzing timed systems are addressed; among the timed systems dealt with are timed automata, timed Petri nets, max-plus algebras, real-time......This book constitutes the thoroughly refereed post-proceedings of the First International Workshop on Formal Modeling and Analysis of Timed Systems, FORMATS 2003, held in Marseille, France in September 2003. The 19 revised full papers presented together with an invited paper and the abstracts...

  5. Cockpit System Situational Awareness Modeling Tool

    Science.gov (United States)

    Keller, John; Lebiere, Christian; Shay, Rick; Latorella, Kara

    2004-01-01

    This project explored the possibility of predicting pilot situational awareness (SA) using human performance modeling techniques for the purpose of evaluating developing cockpit systems. The Improved Performance Research Integration Tool (IMPRINT) was combined with the Adaptive Control of Thought-Rational (ACT-R) cognitive modeling architecture to produce a tool that can model both the discrete tasks of pilots and the cognitive processes associated with SA. The techniques for using this tool to predict SA were demonstrated using the newly developed Aviation Weather Information (AWIN) system. By providing an SA prediction tool to cockpit system designers, cockpit concepts can be assessed early in the design process while providing a cost-effective complement to the traditional pilot-in-the-loop experiments and data collection techniques.

  6. Spatio-temporal modeling of nonlinear distributed parameter systems

    CERN Document Server

    Li, Han-Xiong

    2011-01-01

    The purpose of this volume is to provide a brief review of the previous work on model reduction and identifi cation of distributed parameter systems (DPS), and develop new spatio-temporal models and their relevant identifi cation approaches. In this book, a systematic overview and classifi cation on the modeling of DPS is presented fi rst, which includes model reduction, parameter estimation and system identifi cation. Next, a class of block-oriented nonlinear systems in traditional lumped parameter systems (LPS) is extended to DPS, which results in the spatio-temporal Wiener and Hammerstein s

  7. An ecological process model of systems change.

    Science.gov (United States)

    Peirson, Leslea J; Boydell, Katherine M; Ferguson, H Bruce; Ferris, Lorraine E

    2011-06-01

    In June 2007 the American Journal of Community Psychology published a special issue focused on theories, methods and interventions for systems change which included calls from the editors and authors for theoretical advancement in this field. We propose a conceptual model of systems change that integrates familiar and fundamental community psychology principles (succession, interdependence, cycling of resources, adaptation) and accentuates a process orientation. To situate our framework we offer a definition of systems change and a brief review of the ecological perspective and principles. The Ecological Process Model of Systems Change is depicted, described and applied to a case example of policy driven systems level change in publicly funded social programs. We conclude by identifying salient implications for thinking and action which flow from the Model.

  8. Real-Time System for Water Modeling and Management

    Science.gov (United States)

    Lee, J.; Zhao, T.; David, C. H.; Minsker, B.

    2012-12-01

    Working closely with the Texas Commission on Environmental Quality (TCEQ) and the University of Texas at Austin (UT-Austin), we are developing a real-time system for water modeling and management using advanced cyberinfrastructure, data integration and geospatial visualization, and numerical modeling. The state of Texas suffered a severe drought in 2011 that cost the state $7.62 billion in agricultural losses (crops and livestock). Devastating situations such as this could potentially be avoided with better water modeling and management strategies that incorporate state of the art simulation and digital data integration. The goal of the project is to prototype a near-real-time decision support system for river modeling and management in Texas that can serve as a national and international model to promote more sustainable and resilient water systems. The system uses National Weather Service current and predicted precipitation data as input to the Noah-MP Land Surface model, which forecasts runoff, soil moisture, evapotranspiration, and water table levels given land surface features. These results are then used by a river model called RAPID, along with an error model currently under development at UT-Austin, to forecast stream flows in the rivers. Model forecasts are visualized as a Web application for TCEQ decision makers, who issue water diversion (withdrawal) permits and any needed drought restrictions; permit holders; and reservoir operation managers. Users will be able to adjust model parameters to predict the impacts of alternative curtailment scenarios or weather forecasts. A real-time optimization system under development will help TCEQ to identify optimal curtailment strategies to minimize impacts on permit holders and protect health and safety. To develop the system we have implemented RAPID as a remotely-executed modeling service using the Cyberintegrator workflow system with input data downloaded from the North American Land Data Assimilation System. The

  9. Implementation of a Sage-Based Stirling Model Into a System-Level Numerical Model of the Fission Power System Technology Demonstration Unit

    Science.gov (United States)

    Briggs, Maxwell H.

    2011-01-01

    The Fission Power System (FPS) project is developing a Technology Demonstration Unit (TDU) to verify the performance and functionality of a subscale version of the FPS reference concept in a relevant environment, and to verify component and system models. As hardware is developed for the TDU, component and system models must be refined to include the details of specific component designs. This paper describes the development of a Sage-based pseudo-steady-state Stirling convertor model and its implementation into a system-level model of the TDU.

  10. Reliability modelling and simulation of switched linear system ...

    African Journals Online (AJOL)

    Reliability modelling and simulation of switched linear system control using temporal databases. ... design of fault-tolerant real-time switching systems control and modelling embedded micro-schedulers for complex systems maintenance.

  11. OFFl Models: Novel Schema for Dynamical Modeling of Biological Systems.

    Directory of Open Access Journals (Sweden)

    C Brandon Ogbunugafor

    Full Text Available Flow diagrams are a common tool used to help build and interpret models of dynamical systems, often in biological contexts such as consumer-resource models and similar compartmental models. Typically, their usage is intuitive and informal. Here, we present a formalized version of flow diagrams as a kind of weighted directed graph which follow a strict grammar, which translate into a system of ordinary differential equations (ODEs by a single unambiguous rule, and which have an equivalent representation as a relational database. (We abbreviate this schema of "ODEs and formalized flow diagrams" as OFFL. Drawing a diagram within this strict grammar encourages a mental discipline on the part of the modeler in which all dynamical processes of a system are thought of as interactions between dynamical species that draw parcels from one or more source species and deposit them into target species according to a set of transformation rules. From these rules, the net rate of change for each species can be derived. The modeling schema can therefore be understood as both an epistemic and practical heuristic for modeling, serving both as an organizational framework for the model building process and as a mechanism for deriving ODEs. All steps of the schema beyond the initial scientific (intuitive, creative abstraction of natural observations into model variables are algorithmic and easily carried out by a computer, thus enabling the future development of a dedicated software implementation. Such tools would empower the modeler to consider significantly more complex models than practical limitations might have otherwise proscribed, since the modeling framework itself manages that complexity on the modeler's behalf. In this report, we describe the chief motivations for OFFL, carefully outline its implementation, and utilize a range of classic examples from ecology and epidemiology to showcase its features.

  12. OFFl Models: Novel Schema for Dynamical Modeling of Biological Systems.

    Science.gov (United States)

    Ogbunugafor, C Brandon; Robinson, Sean P

    2016-01-01

    Flow diagrams are a common tool used to help build and interpret models of dynamical systems, often in biological contexts such as consumer-resource models and similar compartmental models. Typically, their usage is intuitive and informal. Here, we present a formalized version of flow diagrams as a kind of weighted directed graph which follow a strict grammar, which translate into a system of ordinary differential equations (ODEs) by a single unambiguous rule, and which have an equivalent representation as a relational database. (We abbreviate this schema of "ODEs and formalized flow diagrams" as OFFL.) Drawing a diagram within this strict grammar encourages a mental discipline on the part of the modeler in which all dynamical processes of a system are thought of as interactions between dynamical species that draw parcels from one or more source species and deposit them into target species according to a set of transformation rules. From these rules, the net rate of change for each species can be derived. The modeling schema can therefore be understood as both an epistemic and practical heuristic for modeling, serving both as an organizational framework for the model building process and as a mechanism for deriving ODEs. All steps of the schema beyond the initial scientific (intuitive, creative) abstraction of natural observations into model variables are algorithmic and easily carried out by a computer, thus enabling the future development of a dedicated software implementation. Such tools would empower the modeler to consider significantly more complex models than practical limitations might have otherwise proscribed, since the modeling framework itself manages that complexity on the modeler's behalf. In this report, we describe the chief motivations for OFFL, carefully outline its implementation, and utilize a range of classic examples from ecology and epidemiology to showcase its features.

  13. Vortex Tube Modeling Using the System Identification Method

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jaeyoung; Jeong, Jiwoong; Yu, Sangseok [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Im, Seokyeon [Tongmyong Univ., Busan (Korea, Republic of)

    2017-05-15

    In this study, vortex tube system model is developed to predict the temperature of the hot and the cold sides. The vortex tube model is developed based on the system identification method, and the model utilized in this work to design the vortex tube is ARX type (Auto-Regressive with eXtra inputs). The derived polynomial model is validated against experimental data to verify the overall model accuracy. It is also shown that the derived model passes the stability test. It is confirmed that the derived model closely mimics the physical behavior of the vortex tube from both the static and dynamic numerical experiments by changing the angles of the low-temperature side throttle valve, clearly showing temperature separation. These results imply that the system identification based modeling can be a promising approach for the prediction of complex physical systems, including the vortex tube.

  14. AN ESTIMATE OF THE NEARBY INTERSTELLAR MAGNETIC FIELD USING NEUTRAL ATOMS

    International Nuclear Information System (INIS)

    Heerikhuisen, J.; Pogorelov, N. V.

    2011-01-01

    The strength and orientation of the magnetic field in the nearby interstellar medium have remained elusive, despite continual improvements in observations and models. Data from NASA's Voyager mission and the Solar Wind ANisotropies (SWAN) experiment on board Solar and Heliospheric Observatory (SOHO) have placed observational constraints on the magnetic field, and the more recent Interstellar Boundary Explorer (IBEX) data appear to also bear an imprint of the interstellar magnetic field (ISMF). In this paper, we combine computational models of the heliosphere with data from Voyager, SOHO/SWAN, and IBEX to estimate both the strength and direction of the nearby ISMF. On the basis of our simulations, we find that a field strength of 2-3 μG pointing from ecliptic coordinates (220-224, 39-44), combined with an interstellar hydrogen density of ∼0.15 cm -3 , produces results most consistent with observations.

  15. Externalizing Behaviour for Analysing System Models

    DEFF Research Database (Denmark)

    Ivanova, Marieta Georgieva; Probst, Christian W.; Hansen, René Rydhof

    2013-01-01

    System models have recently been introduced to model organisations and evaluate their vulnerability to threats and especially insider threats. Especially for the latter these models are very suitable, since insiders can be assumed to have more knowledge about the attacked organisation than outside...... attackers. Therefore, many attacks are considerably easier to be performed for insiders than for outsiders. However, current models do not support explicit specification of different behaviours. Instead, behaviour is deeply embedded in the analyses supported by the models, meaning that it is a complex......, if not impossible task to change behaviours. Especially when considering social engineering or the human factor in general, the ability to use different kinds of behaviours is essential. In this work we present an approach to make the behaviour a separate component in system models, and explore how to integrate...

  16. Integrated Main Propulsion System Performance Reconstruction Process/Models

    Science.gov (United States)

    Lopez, Eduardo; Elliott, Katie; Snell, Steven; Evans, Michael

    2013-01-01

    The Integrated Main Propulsion System (MPS) Performance Reconstruction process provides the MPS post-flight data files needed for postflight reporting to the project integration management and key customers to verify flight performance. This process/model was used as the baseline for the currently ongoing Space Launch System (SLS) work. The process utilizes several methodologies, including multiple software programs, to model integrated propulsion system performance through space shuttle ascent. It is used to evaluate integrated propulsion systems, including propellant tanks, feed systems, rocket engine, and pressurization systems performance throughout ascent based on flight pressure and temperature data. The latest revision incorporates new methods based on main engine power balance model updates to model higher mixture ratio operation at lower engine power levels.

  17. Progress in integrated energy-economy-environment model system development

    International Nuclear Information System (INIS)

    Yasukawa, Shigeru; Mankin, Shuichi; Sato, Osamu; Tadokoro, Yoshihiro; Nakano, Yasuyuki; Nagano, Takao

    1987-11-01

    The Integrated Energy-Economy-Environment Model System has been developed for providing analytical tools for the system analysis and technology assessments in the field of nuclear research and development. This model system consists of the following four model groups. The first model block installs 5 models and can serve to analyze and generate long-term scenarios on economy-energy-environment evolution. The second model block installs 2 models and can serve to analyze the structural transition phenomena in energy-economy-environment interactions. The third model block installs 2 models and can handle power reactor installation strategy problem and long-term fuel cycle analysis. The fourth model block installs 5 models and codes and can treats cost-benefit-risk analysis and assessments. This report describes mainly the progress and the outlines of application of the model system in these years after the first report on the research and development of the model system (JAERI-M 84 - 139). (author)

  18. System-level Modeling of Wireless Integrated Sensor Networks

    DEFF Research Database (Denmark)

    Virk, Kashif M.; Hansen, Knud; Madsen, Jan

    2005-01-01

    Wireless integrated sensor networks have emerged as a promising infrastructure for a new generation of monitoring and tracking applications. In order to efficiently utilize the extremely limited resources of wireless sensor nodes, accurate modeling of the key aspects of wireless sensor networks...... is necessary so that system-level design decisions can be made about the hardware and the software (applications and real-time operating system) architecture of sensor nodes. In this paper, we present a SystemC-based abstract modeling framework that enables system-level modeling of sensor network behavior...... by modeling the applications, real-time operating system, sensors, processor, and radio transceiver at the sensor node level and environmental phenomena, including radio signal propagation, at the sensor network level. We demonstrate the potential of our modeling framework by simulating and analyzing a small...

  19. A Structural Model Decomposition Framework for Systems Health Management

    Science.gov (United States)

    Roychoudhury, Indranil; Daigle, Matthew J.; Bregon, Anibal; Pulido, Belamino

    2013-01-01

    Systems health management (SHM) is an important set of technologies aimed at increasing system safety and reliability by detecting, isolating, and identifying faults; and predicting when the system reaches end of life (EOL), so that appropriate fault mitigation and recovery actions can be taken. Model-based SHM approaches typically make use of global, monolithic system models for online analysis, which results in a loss of scalability and efficiency for large-scale systems. Improvement in scalability and efficiency can be achieved by decomposing the system model into smaller local submodels and operating on these submodels instead. In this paper, the global system model is analyzed offline and structurally decomposed into local submodels. We define a common model decomposition framework for extracting submodels from the global model. This framework is then used to develop algorithms for solving model decomposition problems for the design of three separate SHM technologies, namely, estimation (which is useful for fault detection and identification), fault isolation, and EOL prediction. We solve these model decomposition problems using a three-tank system as a case study.

  20. A structural model decomposition framework for systems health management

    Science.gov (United States)

    Roychoudhury, I.; Daigle, M.; Bregon, A.; Pulido, B.

    Systems health management (SHM) is an important set of technologies aimed at increasing system safety and reliability by detecting, isolating, and identifying faults; and predicting when the system reaches end of life (EOL), so that appropriate fault mitigation and recovery actions can be taken. Model-based SHM approaches typically make use of global, monolithic system models for online analysis, which results in a loss of scalability and efficiency for large-scale systems. Improvement in scalability and efficiency can be achieved by decomposing the system model into smaller local submodels and operating on these submodels instead. In this paper, the global system model is analyzed offline and structurally decomposed into local submodels. We define a common model decomposition framework for extracting submodels from the global model. This framework is then used to develop algorithms for solving model decomposition problems for the design of three separate SHM technologies, namely, estimation (which is useful for fault detection and identification), fault isolation, and EOL prediction. We solve these model decomposition problems using a three-tank system as a case study.