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Sample records for plasmaspheric plumes cluster

  1. Analysis of plasmaspheric plumes: CLUSTER and IMAGE observations and numerical simulations

    Science.gov (United States)

    Darouzet, Fabien; DeKeyser, Johan; Decreau, Pierrette; Gallagher, Dennis; Pierrard, Viviane; Lemaire, Joseph; Dandouras, Iannis; Matsui, Hiroshi; Dunlop, Malcolm; Andre, Mats

    2005-01-01

    Plasmaspheric plumes have been routinely observed by CLUSTER and IMAGE. The CLUSTER mission provides high time resolution four-point measurements of the plasmasphere near perigee. Total electron density profiles can be derived from the plasma frequency and/or from the spacecraft potential (note that the electron spectrometer is usually not operating inside the plasmasphere); ion velocity is also measured onboard these satellites (but ion density is not reliable because of instrumental limitations). The EUV imager onboard the IMAGE spacecraft provides global images of the plasmasphere with a spatial resolution of 0.1 RE every 10 minutes; such images acquired near apogee from high above the pole show the geometry of plasmaspheric plumes, their evolution and motion. We present coordinated observations for 3 plume events and compare CLUSTER in-situ data (panel A) with global images of the plasmasphere obtained from IMAGE (panel B), and with numerical simulations for the formation of plumes based on a model that includes the interchange instability mechanism (panel C). In particular, we study the geometry and the orientation of plasmaspheric plumes by using a four-point analysis method, the spatial gradient. We also compare several aspects of their motion as determined by different methods: (i) inner and outer plume boundary velocity calculated from time delays of this boundary observed by the wave experiment WHISPER on the four spacecraft, (ii) ion velocity derived from the ion spectrometer CIS onboard CLUSTER, (iii) drift velocity measured by the electron drift instrument ED1 onboard CLUSTER and (iv) global velocity determined from successive EUV images. These different techniques consistently indicate that plasmaspheric plumes rotate around the Earth, with their foot fully co-rotating, but with their tip rotating slower and moving farther out.

  2. Analysis of plasmaspheric plumes: CLUSTER and IMAGE observations and numerical simulations

    Science.gov (United States)

    Darouzet, Fabien; DeKeyser, Johan; Decreau, Pierrette; Gallagher, Dennis; Pierrard, Viviane; Lemaire, Joseph; Dandouras, Iannis; Matsui, Hiroshi; Dunlop, Malcolm; Andre, Mats

    2005-01-01

    Plasmaspheric plumes have been routinely observed by CLUSTER and IMAGE. The CLUSTER mission provides high time resolution four-point measurements of the plasmasphere near perigee. Total electron density profiles can be derived from the plasma frequency and/or from the spacecraft potential (note that the electron spectrometer is usually not operating inside the plasmasphere); ion velocity is also measured onboard these satellites (but ion density is not reliable because of instrumental limitations). The EUV imager onboard the IMAGE spacecraft provides global images of the plasmasphere with a spatial resolution of 0.1 RE every 10 minutes; such images acquired near apogee from high above the pole show the geometry of plasmaspheric plumes, their evolution and motion. We present coordinated observations for 3 plume events and compare CLUSTER in-situ data (panel A) with global images of the plasmasphere obtained from IMAGE (panel B), and with numerical simulations for the formation of plumes based on a model that includes the interchange instability mechanism (panel C). In particular, we study the geometry and the orientation of plasmaspheric plumes by using a four-point analysis method, the spatial gradient. We also compare several aspects of their motion as determined by different methods: (i) inner and outer plume boundary velocity calculated from time delays of this boundary observed by the wave experiment WHISPER on the four spacecraft, (ii) ion velocity derived from the ion spectrometer CIS onboard CLUSTER, (iii) drift velocity measured by the electron drift instrument ED1 onboard CLUSTER and (iv) global velocity determined from successive EUV images. These different techniques consistently indicate that plasmaspheric plumes rotate around the Earth, with their foot fully co-rotating, but with their tip rotating slower and moving farther out.

  3. Density structures inside the plasmasphere: Cluster observations

    DEFF Research Database (Denmark)

    Darrouzet, F.; Decreau, P.M.E.; De Keyser, J.;

    2004-01-01

    The electron density profiles derived from the EFW and WHISPER instruments on board the four Cluster spacecraft reveal density structures inside the plasmasphere and at its outer boundary, the plasmapause. We have conducted a statistical study to characterize these density structures. We focus...... on the plasmasphere crossing on I I April 2002, during which Cluster observed several density irregularities inside the plasmasphere, as well as a plasmaspheric plume. We derive the density gradient vectors from simultaneous density measurements by the four spacecraft. We also determine the normal velocity...... of the boundaries of the plume and of the irregularities from the time delays between those boundaries in the four individual density profiles, assuming they are planar. These new observations yield novel insights about the occurrence of density irregularities, their geometry and their dynamics. These in...

  4. Global Circulation and Impact of Plasmaspheric Plumes

    Science.gov (United States)

    Moore, Thomas E.; Fok, Mei-Ching; Chen, Sheng-Hsiem; Delcourt, Dominique C.; Fedder, Joel A.; Slinker, Steven P.

    2008-01-01

    We report results from the global circulation model of Lyon, Fedder, and Mobarry with an embedded model of the inner magnetosphere including the plasmasphere. The combination is used to initiate large numbers of representative protons on the geosynchronous orbit L shell, to assign particle weightings, to track their: subsequent trajectories in the 3D fields. This permits us to study the global circulation of plasmaspheric plumes and to compare these with Polar observations from the dayside magnetopause region . A range of events is studied from an isolated period of SBz in the solar wind,to a large storm sequence. We consider effects on circulating plasma reaching the dayside reconnection X-line, the population of the plasma sheet with ionospheric protons and the generation of ring current pressure from this source, compared with solar wind, polar wind, and auroral wind sources. We find that the transient plasmaspheric plume source is large in terms of total fluence, but of modest proportions in terms of contribution to the ring current. Implications of this and other results for improved space weather modeling and prediction will be discussed.

  5. Detection of a plasmaspheric wind in the Earth's magnetosphere by the Cluster spacecraft

    Directory of Open Access Journals (Sweden)

    I. Dandouras

    2013-07-01

    Full Text Available Plumes, forming at the plasmapause and released outwards, constitute a well-established mode for plasmaspheric material release to the Earth's magnetosphere. They are associated to active periods and the related electric field change. In 1992, Lemaire and Shunk proposed the existence of an additional mode for plasmaspheric material release to the Earth's magnetosphere: a plasmaspheric wind, steadily transporting cold plasmaspheric plasma outwards across the geomagnetic field lines, even during prolonged periods of quiet geomagnetic conditions. This has been proposed on a theoretical basis. Direct detection of this wind has, however, eluded observation in the past. Analysis of ion measurements, acquired in the outer plasmasphere by the CIS experiment onboard the four Cluster spacecraft, provide now an experimental confirmation of the plasmaspheric wind. This wind has been systematically detected in the outer plasmasphere during quiet and moderately active conditions, and calculations show that it could provide a substantial contribution to the magnetospheric plasma populations outside the Earth's plasmasphere. Similar winds should also exist on other planets, or astrophysical objects, quickly rotating and having an atmosphere and a magnetic field.

  6. Remote sensing the plasmasphere, plasmapause, plumes and other features using ground-based magnetometers

    Directory of Open Access Journals (Sweden)

    Menk Frederick

    2014-01-01

    Full Text Available The plasmapause is a highly dynamic boundary between different magnetospheric particle populations and convection regimes. Some of the most important space weather processes involve wave-particle interactions in this region, but wave properties may also be used to remote sense the plasmasphere and plasmapause, contributing to plasmasphere models. This paper discusses the use of existing ground magnetometer arrays for such remote sensing. Using case studies we illustrate measurement of plasmapause location, shape and movement during storms; refilling of flux tubes within and outside the plasmasphere; storm-time increase in heavy ion concentration near the plasmapause; and detection and mapping of density irregularities near the plasmapause, including drainage plumes, biteouts and bulges. We also use a 2D MHD model of wave propagation through the magnetosphere, incorporating a realistic ionosphere boundary and Alfvén speed profile, to simulate ground array observations of power and cross-phase spectra, hence confirming the signatures of plumes and other density structures.

  7. Simulation of EMIC growth and propagation within the plasmaspheric plume density irregularities

    Science.gov (United States)

    de Soria-Santacruz Pich, M.; Spasojevic, M.

    2012-12-01

    In situ data from the Magnetospheric Plasma Analyzer (MPA) instruments onboard the LANL spacecraft are used to study the growth and propagation of electromagnetic ion cyclotron (EMIC) waves in the presence of cold plasma irregularities in the plasmaspheric plume. The data corresponds to the 9 June 2001 event, a period of moderate geomagnetic activity with highly irregular density structure within the plume as measured by the MPA instrument at geosynchoronus orbit. Theory and observations suggest that EMIC waves are responsible for energetic proton precipitation, which is stronger during geomagnetically disturbed intervals. These waves propagate below the proton gyrofrequency, and they appear in three frequency bands due to the presence of heavy ions, which strongly modify wave propagation characteristics. These waves are generated by ion cyclotron instability of ring current ions, whose temperature anisotropy provides the free energy required for wave growth. Growth maximizes for field-aligned propagation near the equatorial plane where the magnetic field gradient is small. Although the wave's group velocity typically stays aligned with the geomagnetic field direction, wave-normal vectors tend to become oblique due to the curvature and gradient of the field. On the other hand, radial density gradients have the capability of guiding the waves and competing against the magnetic field effect thus favoring wave growth conditions. In addition, enhanced cold plasma density reduces the proton resonant energy where higher fluxes are available for resonance, and hence explaining why wave growth is favored at higher L-shell regions where the ratio of plasma to cyclotron frequency is larger. The Stanford VLF 3D Raytracer is used together with path-integrated linear growth calculations to study the amplification and propagation characteristics of EMIC waves within the plasmaspheric plume formed during the 9 June 2001 event. Cold multi-ion plasma is assumed for raytracing

  8. Resonant Scattering of Relativistic Outer Zone Electrons by Plasmaspheric Plume Electromagnetic Ion Cyclotron Waves

    Institute of Scientific and Technical Information of China (English)

    SU Zhen-Peng; ZHENG Hui-Nan

    2009-01-01

    The bounce-averaged Fokker-Planck equation is solved to study the relativistic electron phase space density(PSD)evolution in the outer radiation belt due to resonant interactions with plasmaspheric plume electromagnetic ion cyclotron(EMIC)waves.It is found that the PSDs of relativistic electrons can be depleted by 1-3 orders of magnitude in 5h,supporting the previous finding that resonant interactions with EMIC waves may account for the frequently observed relativistic electron flux dropouts in the outer radiation belt during the main phase of a storm.The significant precipitation Joss of ~Me V electrons is primarily induced by the EMIC waves in H~+ and He~+ bands.The rapid remove of highly relativistic electrons(>5 MeV)is mainly driven by the EMIC waves in O~+ band at lower pitch-angles,as well as the EMIC waves in H~+ and He~+ bands at larger pitch-angles.Moreover,a stronger depletion of relativistic electrons is found to occur over a wider pitch angle range when EMIC waves are centering relatively higher in the band.

  9. Refilling process in the plasmasphere: a 3-D statistical characterization based on Cluster density observations

    Directory of Open Access Journals (Sweden)

    G. Lointier

    2013-02-01

    Full Text Available The Cluster mission offers an excellent opportunity to investigate the evolution of the plasma population in a large part of the inner magnetosphere, explored near its orbit's perigee, over a complete solar cycle. The WHISPER sounder, on board each satellite of the mission, is particularly suitable to study the electron density in this region, between 0.2 and 80 cm−3. Compiling WHISPER observations during 1339 perigee passes distributed over more than three years of the Cluster mission, we present first results of a statistical analysis dedicated to the study of the electron density morphology and dynamics along and across magnetic field lines between L = 2 and L = 10. In this study, we examine a specific topic: the refilling of the plasmasphere and trough regions during extended periods of quiet magnetic conditions. To do so, we survey the evolution of the ap index during the days preceding each perigee crossing and sort out electron density profiles along the orbit according to three classes, namely after respectively less than 2 days, between 2 and 4 days, and more than 4 days of quiet magnetic conditions (ap ≤ 15 nT following an active episode (ap > 15 nT. This leads to three independent data subsets. Comparisons between density distributions in the 3-D plasmasphere and trough regions at the three stages of quiet magnetosphere provide novel views about the distribution of matter inside the inner magnetosphere during several days of low activity. Clear signatures of a refilling process inside an expended plasmasphere in formation are noted. A plasmapause-like boundary, at L ~ 6 for all MLT sectors, is formed after 3 to 4 days and expends somewhat further after that. In the outer part of the plasmasphere (L ~ 8, latitudinal profiles of median density values vary essentially according to the MLT sector considered rather than according to the refilling duration. The shape of these density profiles

  10. Spatial and temporal characteristics of poloidal waves in the terrestrial plasmasphere: a CLUSTER case study

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    S. Schäfer

    2007-05-01

    Full Text Available Oscillating magnetic field lines are frequently observed by spacecraft in the terrestrial and other planetary magnetospheres. The CLUSTER mission is a very suitable tool to further study these Alfvén waves as the four CLUSTER spacecraft provide for an opportunity to separate spatial and temporal structures in the terrestrial magnetosphere. Using a large scaled configuration formed by the four spacecraft we are able to detect a poloidal Ultra-Low-Frequency (ULF pulsation of the magnetic and electric field in order to analyze its temporal and spatial structures. For this purpose the measurements are transformed into a specific field line related coordinate system to investigate their specific amplitude pattern depending on the path of the CLUSTER spacecraft across oscillating field lines. These measurements are then compared with modeled spacecraft observations across a localized poloidal wave resonator in the dayside plasmasphere. A detailed investigation of theoretically expected poloidal eigenfrequencies allows us to specify the observed 16 mHz pulsation as a third harmonic oscillation. Based on this we perform a case study providing a clear identification of wave properties such as an spatial scale structure of about 0.67 RE, the azimuthal wave number m≈30, temporal evolution, and energy transport in the detected ULF pulsations.

  11. Physics-based models of the plasmasphere

    Energy Technology Data Exchange (ETDEWEB)

    Jordanova, Vania K [Los Alamos National Laboratory; Pierrard, Vivane [BELGIUM; Goldstein, Jerry [SWRI; Andr' e, Nicolas [ESTEC/ESA; Kotova, Galina A [SRI, RUSSIA; Lemaire, Joseph F [BELGIUM; Liemohn, Mike W [U OF MICHIGAN; Matsui, H [UNIV OF NEW HAMPSHIRE

    2008-01-01

    We describe recent progress in physics-based models of the plasmasphere using the Auid and the kinetic approaches. Global modeling of the dynamics and inAuence of the plasmasphere is presented. Results from global plasmasphere simulations are used to understand and quantify (i) the electric potential pattern and evolution during geomagnetic storms, and (ii) the inAuence of the plasmasphere on the excitation of electromagnetic ion cyclotron (ElvIIC) waves a.nd precipitation of energetic ions in the inner magnetosphere. The interactions of the plasmasphere with the ionosphere a.nd the other regions of the magnetosphere are pointed out. We show the results of simulations for the formation of the plasmapause and discuss the inAuence of plasmaspheric wind and of ultra low frequency (ULF) waves for transport of plasmaspheric material. Theoretical formulations used to model the electric field and plasma distribution in the plasmasphere are given. Model predictions are compared to recent CLUSTER and MAGE observations, but also to results of earlier models and satellite observations.

  12. The Plasmasphere Boundary Layer

    Directory of Open Access Journals (Sweden)

    D. L. Carpenter

    2004-12-01

    Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere.

    Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

  13. Whistlers Observed Outside the Plasmasphere: Correlation to Plasmaspheric/Plasmapause Features and Implications for the Scattering of Radiation-Belt Electrons

    Science.gov (United States)

    Adrian, Mark L.; Gallagher, D. L.

    2007-01-01

    Magnetospherically reflected, lightning-generated whistler waves are an important potential contributor to pitch-angle scattering loss processes of the electron radiation belts. While lightning-generated whistlers are a common feature at, and just inside, the plasmapause, they are infrequently observed outside the plasmasphere. As such, their potential contribution to outer radiation belt loss processes is more tenuous. Recently, Platino et al. [2005] has reported on whistlers observed outside the plasmasphere by Cluster. Here, we present correlative global observations of the plasmasphere, for the reported periods of Cluster-observed whistlers outside the plasmasphere, using IMAGE-EUV data. The intent of this study is to seek the underlying mechanisms that result in whistlers outside the plasmasphere and consequently the anticipated morphology and significance these waves may have on radiation belt dynamics.

  14. The EtnaPlumeLab (EPL research cluster: advance the understanding of Mt. Etna plume, from source characterisation to downwind impact

    Directory of Open Access Journals (Sweden)

    Pasquale Sellitto

    2017-01-01

    Full Text Available In 2013, a multidisciplinary research cluster named EtnaPlumeLab (EPL was established, gathering experts from volcanology and atmospheric science communities. Target of EPL is to advance the understanding of Mt. Etna's gas and aerosol emissions and the related processes, from source to its regional climatic impact in the Mediterranean area. Here, we present the cluster and its three interacting modules: EPL-RADIO (Radioactive Aerosols and other source parameters for better atmospheric Dispersion and Impact estimatiOns, SMED (Sulfur MEditerranean Dispersion and Med-SuV (MEDiterranean SUpersite Volcanoes Work Package 5. Preliminary results have for the first time highlighted the relevance of Mt. Etna's plume impact at the Mediterranean regional scale. These results underline that further efforts need to be made to get insight into a synoptic volcanogenic-atmospheric chemistry/climatic understanding of volcanic plumes impact.

  15. Unsolved problems in plasmasphere refilling

    Science.gov (United States)

    Gallagher, D. L.; Comfort, R. H.

    2016-02-01

    The plasmasphere is a cold (~1 eV) plasma at middle to low magnetic latitudes surrounding the Earth. Its shape is dominated by Earth's magnetic field and its cross-field motion is dominated by electric fields. It is a highly coupled part of the inner magnetosphere. Storm time conditions erode the outer plasmasphere, transporting that plasma into the dayside magnetosheath region, leaving behind a region of greatly reduced plasma density that will refill from ionospheric outflow. The processes involved in refilling remain incompletely understood. In this commentary, outstanding questions about plasmaspheric refilling are summarized in the context of recent publications.

  16. Calculation of the extreme ultraviolet radiation of the earth’s plasmasphere

    Institute of Scientific and Technical Information of China (English)

    FOK; Mei-Ching

    2010-01-01

    The dynamic global core plasma model(DGCPM) is used in this paper to calculate the He+ density distribution of the Earth’s plasmasphere and to investigate the configurations and 30.4 nm radiation properties of the plasmasphere.Validation comparisons between the simulation results and IMAGE mission observations show:That the equatorial structure of the plasmapause is mainly located near 5.5 RE and the typical scale of plasmasphere shrinking or expansion within 10 min is approximately 0.1 RE;that the plasmaspheric shoulders are formed and rotate noon-ward from the dawn sector under the conditions of strong southward turning of the interplanetary magnetic field(IMF);that the plasmaspheric plumes will rotate dawn-ward from the night sector and become narrow for the southward turning of the IMF.The simulated images from the lunar orbit show that the plasmasphere locating within the geocentric distance of 5.5 RE corresponds to field of view(FOV) of 10.7°×10.7° for the moon-based EUV imager,and that the 30.4 nm radiation intensity of the plasmasphere is 0.1-11.4 R.The plasmaspheric shoulders and plumes locating toward the moon-side are for the first time simulated with typical scale level of 0.1 RE from the side view of the moon.These simulated results provide an important theoretical basis for the lunar-based EUV camera design.

  17. Saturn's ionosphere and plasmasphere

    Science.gov (United States)

    Moore, Luke Edward

    2008-01-01

    A number of puzzling phenomena were revealed when the Voyager spacecraft flew past Saturn in 1981 to measure the ionized portions (ionosphere) of its upper atmosphere (thermosphere). Most of these issues have remained unexplained in the intervening 25 years due to a lack of conclusive observational data. With the arrival of Cassini at Saturn in July 2004, however, a new era of observations began, providing the promise of fresh evidence and demanding the development of a contemporary theoretical framework in order to re-examine old mysteries and understand new discoveries. This dissertation presents studies of Saturn's ionosphere and inner plasmasphere based on new time-dependent photochemical and diffusive transport models that solve the ion equations of continuity in one dimension. Calculations are conducted within the overall framework of a self-consistent, three-dimensional general circulation model (GCM) of Saturn's thermosphere, and the results of these studies are combined with GCM results to provide the building blocks of a new comprehensive model, the Saturn-Thermosphere- Ionosphere-Model (STIM). The one-dimensional model calculations are used to constrain and investigate a number of unresolved issues and to make testable predictions based on those investigations. Five primary topics are addressed: (1) the additional loss processes required to bring predicted electron densities into agreement with observations, (2) the discrepancy between theory and observations regarding the diurnal variation of peak electron density, (3) the effects of shadowing by Saturn's rings on its ionosphere, (4) the yet unknown electron and ion temperatures at Saturn, and (5) the ionospheric contribution to Saturn's plasmasphere. The models show that a steady influx of water into Saturn's atmosphere--from its rings or icy satellites--is required to explain observed electron densities. Additionally, the time-variability of the water source may be the cause of frequently observed

  18. Whistler Wave Energy Flow in the Plasmasphere

    Science.gov (United States)

    Kletzing, Craig; Santolik, Ondrej; Kurth, William; Hospodarsky, George; Christopher, Ivar; Bounds, Scott

    2016-07-01

    The measured wave properties of plasmaspheric hiss are important to constrain models of the generation of hiss as well as its propagation and amplification. For example, the generation mechanism for plasmaspheric hiss has been suggested to come from one of three possible mechanisms: 1) local generation and amplification, 2) whistlers from lightning, and 3) chorus emissions which have refracted into the plasmasphere. The latter two mechanisms are external sources which produce an incoherent hiss signature as the original waves mix in a stochastic manner, propagating in both directions along the background magnetic field. In contrast, local generation of plasmaspheric hiss within the plasmasphere should produce a signature of waves propagating away from the source region. For all three mechanisms scattering of energetic particles into the loss cone transfers some energy from the particles to the waves. By examining the statistical characteristics of the Poynting flux of plasmaspheric hiss, we can determine the properties of wave energy flow in the plasmasphere. We report on the statistics of observations from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) Waves instrument on the Van Allen Probes for periods when the spacecraft is inside the plasmasphere. We find that the Poynting flux associated with plasmaspheric hiss has distinct and unexpected radial structure which shows that there can be significant energy flow towards the magnetic equator. We show the properties of this electromagnetic energy flow as a function of position and frequency.

  19. Refilling the plasmasphere through the exospheric sieve

    Science.gov (United States)

    Krall, J.; Huba, J.; Emmert, J. T.

    2016-12-01

    The ability to compute plasmasphere densities is critical to many space weather concerns. The sensitivity of refilling to the solar cycle is compelling because, paradoxically, refilling rates are generally lowest when the ionosphere is strongest. In the past, this has been attributed to a dearth of exosphere H at solar maximum. While H is needed to supply H + O+ -> H+ + O charge exchange, recent work demonstrates a significant sensitivity to O [1]. Results will be based on preliminary model-data comparisons using in situ Van Allen Probe EMFISIS data and the SAMI3 ionosphere/plasmasphere code. We will assess the impact of atmospheric composition (i.e., O and H) and solar activity (e.g., F10.7) on plasmasphere refilling rates and density following magnetic storms. SAMI3 (Sami3 is Also a Model of the Ionosphere) is a first-principles ionosphere/plasmasphere model. SAMI3 includes 7 ion species (H+, He+, O+, N+, O2+, N2+, NO+), each treated as a separate fluid, with temperature equations being solved for H+, He+, O+ and e- [2]. SAMI3 uses the empirical MSIS thermosphere/exosphere model to specify O and H densities. SAMI3 includes scaling factors that can be used to tune MSIS densities to bring them in line with measurements of satellite drag. Key inputs for this data-driven modeling are the thermosphere oxygen (O) and hydrogen (H) densities, and the F10.7 proxy for solar ultraviolet irradiance. [1 ]Krall, J., J. T. Emmert, F. Sassi, S. E. McDonald, and J. D. Huba (2016), Day-to-day variability in the thermosphere and its impact on plasmasphere refilling, J. Geophys. Res. Space Physics, 121, doi:10.1002/2015JA022328. [2] Huba, J. and J. Krall (2013), Modeling the plasmasphere with SAMI3, Geophys. Res. Lett., 40, 6-10, doi:10.1029/2012GL054300 Research supported by NRL base funds.

  20. Turbulent Plasmaspheric Boundary Layer: Observables and Consequences

    Science.gov (United States)

    Mishin, Evgeny

    2014-10-01

    In situ satellite observations reveal strong lower hybrid/fast magnetosonic turbulence and broadband hiss-like VLF waves in the substorm subauroral geospace at and earthward of the electron plasmasheet boundary. These coincide with subauroral ion drifts/polarization streams (SAID/SAPS) in the plasmasphere and topside ionosphere. SAID/SAPS appear in ~10 min after the substorm onset consistent with the fast propagation of substorm injection fronts. The SAID channel follows the dispersionless cutoff of the energetic electron flux at the plasmapause. This indicates that the cold plasma maintains charge neutrality within the channel, thereby short-circuiting the injected plasma jet (injection fronts over the plasmasphere. Plasma turbulence leads to the circuit resistivity and magnetic diffusion as well as significant electron heating and acceleration. As a result, a turbulent boundary layer forms between the inner edge of the electron plasmasheet and plasmasphere. The SAID/SAPS-related VLF emissions appear to constitute a distinctive subset of substorm/storm-related VLF activity in the region co-located with freshly injected energetic ions inside the plasmasphere. Significant pitch-angle diffusion coefficients suggest that substorm SAID/SAPS-related VLF waves could be responsible for the alteration of the outer radiation belt boundary during (sub)storms. Supported by the Air Force Office of Scientific Research.

  1. Evidence for Significant Local Generation of Plasmaspheric Hiss

    Science.gov (United States)

    Kletzing, C.; Kurth, W. S.; Bounds, S. R.; Hospodarsky, G. B.; Santolik, O.; Wygant, J. R.; Bonnell, J. W.; Omura, Y.; Summers, D.

    2014-12-01

    The source of plasmaspheric hiss has been an outstanding problem in inner magnetospheric radiation belt physics since the discovery of this whistler-mode emission. The generation mechanism for plasmaspheric hiss has been suggested to come from one of three possible mechanisms: 1) local generation and amplification, 2) whistlers from lightning, and 3) chorus emissions which have refracted into the plasmasphere. The latter two mechanisms are external sources which produce an incoherent hiss signature as the original waves mix in a stochastic manner, propagating in both directions along the background magnetic field. In contrast, local generation of plasmaspheric hiss within the plasmasphere should produce a signature of waves propagating away from the source region. We report observations from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) Waves insturment on the Van Allen Probes that clearly indicate that the Poynting flux associated with plasmaspheric hiss is frequently propagating away from the equator in the outer region of the plasmasphere. Initial statistics suggest that for more than 40% of the orbits of the Van Allen Probes, the plasmaspheric hiss is generated by a local source within the plasmasphere. We present examples of the signature of locally generated plasmaspheric hiss and show additional statistics of locally generated hiss occurrence.

  2. Banded electron structures in the plasmasphere

    Energy Technology Data Exchange (ETDEWEB)

    Burke, W.J.; Rubin, A.G.; Hardy, D.A.; Holeman, E.G.

    1995-05-01

    The low-energy plasma analyzer on CRRES has detected significant fluxes of 10-eV to 30-keV electrons trapped on plasmaspheric field lines. On energy versus time spectrograms these electrons appear as banded structures that can span the 2 < L < 6 range of magnetic shells. The authors present an example of banded electron structures, encountered in the nightside plasmasphere during the magnetically quiet January 30, 1991. Empirical analysis suggests that two clouds of low energy electrons were injected from the plasma sheet to L < 4 on January 26 and 27 while the convective electric field was elevated. The energies of electrons in the first cloud were greater than those in the second. DMSP F8 measurements show that after the second injection, the polar cap potential rapidly decreased from >50 to <20 kY. Subsequent encounters with the lower energy cloud on alternating CRRES orbits over the next 2 days showed a progressive, earthward movement of the electrons, inner boundary. Whistler and electron cyclotron harmonic emissions accompanied the most intense manifestations of cloud electrons. The simplest explanation of these measurements is that after initial injection, the AIfven boundary moved Outward, leaving the cloud electrons on closed drift paths. Subsequent fluctuations of the convective electric field penetrated the plasmasphere, transporting cloud elements inward. The magnetic shell distribution of electron temperatures in one of the banded structures suggests that radiative energy losses may be comparable in magnitude to gains due to adiabatic compression.

  3. A New Global Core Plasma Model of the Plasmasphere

    Science.gov (United States)

    Gallagher, D. L.; Comfort, R. H.; Craven, P. D.

    2014-01-01

    The Global Core Plasma Model (GCPM) is the first empirical model for thermal inner magnetospheric plasma designed to integrate previous models and observations into a continuous in value and gradient representation of typical total densities. New information about the plasmasphere, in particular, makes possible significant improvement. The IMAGE Mission Radio Plasma Imager (RPI) has obtained the first observations of total plasma densities along magnetic field lines in the plasmasphere and polar cap. Dynamics Explorer 1 Retarding Ion Mass Spectrometer (RIMS) has provided densities in temperatures in the plasmasphere for 5 ion species. These and other works enable a new more detailed empirical model of thermal in the inner magnetosphere that will be presented.

  4. Measurement and modeling of the refilling plasmasphere during 2001

    Science.gov (United States)

    Krall, J.; Huba, J. D.; Jordanova, V. K.; Denton, R. E.; Carranza, T.; Moldwin, M. B.

    2016-03-01

    The Naval Research Laboratory SAMI3 (Sami3 is Also a Model of the Ionosphere) and the RAM-CPL (Ring current Atmosphere interaction Model-Cold PLasma) codes are used to model observed plasmasphere dynamics during 25 November 2001 to 1 December 2001 and 1-5 February 2001. Model results compare well to plasmasphere observations of electron and mass densities. Comparison of model results to refilling data and to each other shows good agreement, generally within a factor of 2. We find that SAMI3 plasmaspheric refilling rates and ion densities are sensitive to the composition and temperature of the thermosphere and exosphere, and to photoelectron heating. Results also support our previous finding that the wind-driven dynamo significantly impacts both refilling rates and plasmasphere dynamics during quiet periods.

  5. The Influence of the Solar Cycle on Plasmasphere Refilling

    Science.gov (United States)

    Krall, J.; Huba, J.

    2015-12-01

    During refilling, ionospheric plasma streams into the inner magnetosphere from both the northern and southern hemispheres. Plasmasphere refilling rates depend on both the ionospheric sources and on the thermalization of streaming ions. We use the NRL SAMI3 ionosphere/plasmasphere code[1] coupled to the NRLMSIS empirical atmosphere model and the HWM14 empirical wind model, to simulate H+, He+ and O+ populations in the plasmasphere. The SAMI3 ionosphere code includes 7 ion species (H+, He+, O+, N+, O2+, N2+, NO+), each treated as a separate fluid, with temperature equations being solved for H+, He+, O+ and e. Measurements show that refilling rates decrease with increasing solar activity, an effect reproduced by SAMI3 and its two-dimensional cousin, SAMI2. We find that the refilling rate and the resulting the plasmasphere electron content are sensitive to the thermospheric composition and temperature, as well as photoelectron heating and photoproduction rates. Depending on conditions, simulations suggest that the plasmaspheric contribution to the total electron content can either increase or decrease with solar activity, as represented by the daily and 81-day-average F10.7 indices. [1] Huba, J. and J. Krall, 2013, ``Modeling the plasmasphere with SAMI3'', Geophys. Res. Lett. 40, 6--10, doi:10.1029/2012GL054300 Research supported by NRL base funds and the NASA HSR program.

  6. Analysis of the IMAGE RPI electron density data and CHAMP plasmasphere electron density reconstructions with focus on plasmasphere modelling

    Science.gov (United States)

    Gerzen, T.; Feltens, J.; Jakowski, N.; Galkin, I.; Reinisch, B.; Zandbergen, R.

    2016-09-01

    The electron density of the topside ionosphere and the plasmasphere contributes essentially to the overall Total Electron Content (TEC) budget affecting Global Navigation Satellite Systems (GNSS) signals. The plasmasphere can cause half or even more of the GNSS range error budget due to ionospheric propagation errors. This paper presents a comparative study of different plasmasphere and topside ionosphere data aiming at establishing an appropriate database for plasmasphere modelling. We analyze electron density profiles along the geomagnetic field lines derived from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite/Radio Plasma Imager (RPI) records of remote plasma sounding with radio waves. We compare these RPI profiles with 2D reconstructions of the topside ionosphere and plasmasphere electron density derived from GNSS based TEC measurements onboard the Challenging Minisatellite Payload (CHAMP) satellite. Most of the coincidences between IMAGE profiles and CHAMP reconstructions are detected in the region with L-shell between 2 and 5. In general the CHAMP reconstructed electron densities are below the IMAGE profile densities, with median of the CHAMP minus IMAGE residuals around -588 cm-3. Additionally, a comparison is made with electron densities derived from passive radio wave RPI measurements onboard the IMAGE satellite. Over the available 2001-2005 period of IMAGE measurements, the considered combined data from the active and passive RPI operations cover the region within a latitude range of ±60°N, all longitudes, and an L-shell ranging from 1.2 to 15. In the coincidence regions (mainly 2 ⩽ L ⩽ 4), we check the agreement between available active and passive RPI data. The comparison shows that the measurements are well correlated, with a median residual of ∼52 cm-3. The RMS and STD values of the relative residuals are around 22% and 21% respectively. In summary, the results encourage the application of IMAGE RPI data for

  7. The story of plumes: the development of a new conceptual framework for understanding magnetosphere and ionosphere coupling

    Science.gov (United States)

    Moldwin, Mark B.; Zou, Shasha; Heine, Tom

    2016-12-01

    The name "plume" has been given to a variety of plasma structures in the Earth's magnetosphere and ionosphere. Some plumes (such as the plasmasphere plume) represent elevated plasma density, while other plumes (such as the equatorial F region plume) represent low-density regions. Despite these differences these structures are either directly related or connected in the causal chain of plasma redistribution throughout the system. This short review defines how plumes appear in different measurements in different regions and describes how plumes can be used to understand magnetosphere-ionosphere coupling. The story of the plume family helps describe the emerging conceptual framework of the flow of high-density-low-latitude ionospheric plasma into the magnetosphere and clearly shows that strong two-way coupling between ionospheric and magnetospheric dynamics occurs not only in the high-latitude auroral zone and polar cap but also through the plasmasphere. The paper briefly reviews, highlights and synthesizes previous studies that have contributed to this new understanding.

  8. Storm-Time Strong Field-Aligned Ion Upflow in Region of the SED Plume

    Institute of Scientific and Technical Information of China (English)

    YUAN Zhi-Gang; DENG Xiao-Hua; WANG Jing-Fang

    2008-01-01

    report the observations from the GPS TEC and DMSP F-13 satellites showing that very strong upward field-aligned (FA) ion velocity and flux in the outer region of the storm-enhanced density (SED) occurred in the event of the geomagnetic storm on 29-31 May 2003. By a method of coordinate transformation, upward FA ion velocities in excess of 250m/s are obtained from the observations of the DMSP F-13 satellite. Further, an FA ion flux is estimated to be about 4.5×1013ions/m2s in the dusk sector. The estimated FA ion velocity and flux provide a powerful direct proof to support the scenario that there is a strong coupling of particles between the ionosphere and plasmasphere in the region of the SED plume. In the process, FA ion flux transports from the ionosphere to the plasmasphere in the region of the SED plume. Therefore, the plume of SED in the ionosphere provides an important source to the enhanced density of O+ in the storm-time plasmasphere.

  9. Response of plasmaspheric configuration to substorms revealed by Chang’e 3

    Science.gov (United States)

    He, Han; Shen, Chao; Wang, Huaning; Zhang, Xiaoxin; Chen, Bo; Yan, Jun; Zou, Yongliao; Jorgensen, Anders M.; He, Fei; Yan, Yan; Zhu, Xiaoshuai; Huang, Ya; Xu, Ronglan

    2016-08-01

    The Moon-based Extreme Ultraviolet Camera (EUVC) of the Chang’e 3 mission provides a global and instantaneous meridian view (side view) of the Earth’s plasmasphere. The plasmasphere is one inner component of the whole magnetosphere, and the configuration of the plasmasphere is sensitive to magnetospheric activity (storms and substorms). However, the response of the plasmaspheric configuration to substorms is only partially understood, and the EUVC observations provide a good opportunity to investigate this issue. By reconstructing the global plasmaspheric configuration based on the EUVC images observed during 20–22 April 2014, we show that in the observing period, the plasmasphere had three bulges which were located at different geomagnetic longitudes. The inferred midnight transit times of the three bulges, using the rotation rate of the Earth, coincide with the expansion phase of three substorms, which implies a causal relationship between the substorms and the formation of the three bulges on the plasmasphere. Instead of leading to plasmaspheric erosion as geomagnetic storms do, substorms initiated on the nightside of the Earth cause local inflation of the plasmasphere in the midnight region.

  10. Plasmaspheric trough evolution under different conditions of subauroral ion drift

    Institute of Scientific and Technical Information of China (English)

    HE Fei; ZHANG XiaoXin; CHEN Bo; FOK MeiChing

    2012-01-01

    The statistical characteristics of the subauroral ion drift (SAID) in the ionosphere and the plasmaspheric trough evolution under different conditions of SAID were investigated in this paper,based on 566 SAID events observed by Akebono,Astrid-2,DE-2,and Freja satellites.The relationships between the latitudinal location of SAID and the Kp,AL,and Dst indices for these events were also discussed.It was found that the SAID events happened mainly at invariant latitude (ILAT) of 60.4° and magnetic local time (MLT) of 21.6 MLT and that 92.4% of the events happened when the Kp index was below 5.0,indicating a medium geomagnetic activity.The latitudinal half-width of SAID varied from 0.5° to 3.0° with a typical half-width of 1.0°.The SAID would happen at low latitudes if the geomagnetic activity was high.The effects of SAID on equatorial outer plasmasphere trough evolutions were studied with the dynamic global core plasma model (DGCPM) driven by the statistical results of SAID signatures.It was noted that locations,shapes and density of troughs vary with ILAT,MLT,latitudinal width,cross polar cap potential and lifetime of SAID events.The evolution of a trough is determined by the extent of SAID electric field penetrating into plasmasphere and not all SAID events can result in trough formations.

  11. Improved analysis of plasmasphere motion using the VLA radio interferometer

    Directory of Open Access Journals (Sweden)

    G. W. Hoogeveen

    Full Text Available Observations using the very large (VLA radio interferometer during the past five years have enabled the discovery of a new type of plasmasphere disturbance, the magnetic eastward-directed wave. Previous work indicated these disturbances were likely frozen to the geomagnetic field as determined from their azimuth distributions. This work provides a method to explain more accurately the azimuth distribution, thereby allowing the calculation of the disturbances' location in the plasmasphere independently of the measured velocity. The measurable velocity due to corotation is calculated and subtracted from the measured trace velocity. This difference, or deviation from corotation, is attributed to electrodynamic convection; the measurement of plasmaspheric convection may lead to the eventual monitoring of mid-latitude electric fields. Disturbances are seen convecting predominantly westward, with the fastest having angular velocities greater than the anticorotating VLA line of sight. The direction of convection and conditions of observations indicate that the disturbances are likely the same phenomenon seen by the Los Alamos satellite beacon array.

  12. On the Origin of Whistler Mode Radiation in the Plasmasphere

    Science.gov (United States)

    Green, James L.; Boardsen, Scott; Garcia, Leonard; Taylor, W. W. L.; Fung, Shing F.; Reinisch, B. W.

    2004-01-01

    The origin of whistler mode radiation in the plasmasphere is examined from three years of plasma wave observations from the Dynamics Explorer and three years from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft. These data are used to construct plasma wave intensity maps of whistler mode radiation in the plasmasphere. The highest average intensities of the radiation in the wave maps show source locations and/or sites of wave amplification. Each type of emission is classified based on its magnetic latitude and longitude rather than any spectral feature. Equatorial electromagnetic (EM) emissions (approx. 30-330 Hz), plasmaspheric hiss (approx. 330 Hz - 3.3 kHz), chorus (approx. 2 kHz - 6 kHz), and VLF transmitters (approx. 10-50 kHz) are the main types of waves that are clearly delineated in the plasma wave maps. Observations of the equatorial EM emissions show that the most intense region is on or near the magnetic equator in the afternoon sector and that during times of negative B(sub z) (interplanetary magnetic field),the maximum intensity moves from L values of 3 to less than 2. These observations are consistent with the origin of this emission being particle-wave interactions in or near the magnetic equator. Plasmaspheric hiss shows high intensity at high latitudes and low altitudes (L shells from 2 to 4) and in the magnetic equator over L values from 2 to 3 in the early afternoon sector. The longitudinal distribution of the hiss intensity (excluding the enhancement at the equator) is similar to the distribution of lightning: stronger over continents than over the ocean, stronger in the summer than winter, and stronger on the dayside than nightside. These observations strongly support lightning as the dominant source for plasmaspheric hiss, which through particle-wave interactions, maintains the slot region in the radiation belts. The enhancement of hiss at the magnetic equator is consistent with particle-wave interactions. The chorus

  13. ASSESSMENT OF PLUME DIVING

    Science.gov (United States)

    This presentation presents an assessment of plume diving. Observations included: vertical plume delineation at East Patchogue, NY showed BTEX and MTBE plumes sinking on either side of a gravel pit; Lake Druid TCE plume sank beneath unlined drainage ditch; and aquifer recharge/dis...

  14. Driving Plasmaspheric Electron Density Simulations During Geomagnetic Storms

    Science.gov (United States)

    De Pascuale, S.; Kletzing, C.; Jordanova, V.; Goldstein, J.; Wygant, J. R.; Thaller, S. A.

    2015-12-01

    We test global convection electric field models driving plasmaspheric electron density simulations (RAM-CPL) during geomagnetic storms with in situ measurements provided by the Van Allen Probes (RBSP). RAM-CPL is the cold plasma component of the ring-current atmosphere interactions suite (RAM-SCB) and describes the evolution of plasma density in the magnetic equatorial plane near Earth. Geomagnetic events observed by the RBSP satellites in different magnetic local time (MLT) sectors enable a comparison of local asymmetries in the input electric field and output densities of these simulations. Using a fluid MHD approach, RAM-CPL reproduces core plasmaspheric densities (L<4) to less than 1 order of magnitude difference. Approximately 80% of plasmapause crossings, defined by a low-density threshold, are reproduced to within a mean radial difference of 0.6 L. RAM-CPL, in conjunction with a best-fit driver, can be used in other studies as an asset to predict density conditions in locations distant from RBSP orbits of interest.

  15. Wave-Particle Interactions in the Turbulent Plasmaspheric Boundary Layer

    Science.gov (United States)

    Mishin, Evgeny

    2012-10-01

    We present in situ satellite observations of plasmaspheric lower hybrid/fast magnetosonic turbulence and broadband hiss-like VLF emissions related with substorm subauroral ion drifts/polarization streams (SAID/SAPS) in the magnetosphere and topside ionosphere. SAID/SAPS appear in ˜10 min after the substorm onset consistent with the fast propagation of substorm injection fronts. The SAID channel follows the dispersionless cutoff of the energetic electron flux at the plasmapause. This indicates that the cold plasma maintains charge neutrality within the channel, thereby short-circuiting the injected plasmoid (injection front) over the plasmasphere. As with the well-documented plasmoid-magnetic barrier problem, plasma turbulence ensures the circuit resistivity and magnetic diffusion as well as significant electron heating and acceleration. The SAID/SAPS-related VLF emissions were used to simulate interactions with the outer zone electrons. These emissions appear to constitute a distinctive subset of substorm/storm-related VLF activity in the region co-located with freshly injected energetic ions equatorward of the plasma sheet boundary. Significant pitch-angle diffusion coefficients suggest that substorm SAID/SAPS-related VLF waves could be responsible for the alteration of the outer radiation belt boundary during (sub)storms.

  16. Plasmaspheric H+, He+, O+, He++, and O++ Densities and Temperatures

    Science.gov (United States)

    Gallagher, D. L.; Craven, P. D.; Comfort H.

    2013-01-01

    Thermal plasmaspheric densities and temperatures for five ion species have recently become available, even though these quantities were derived some time ago from the Retarding Ion Mass Spectrometer onboard the Dynamics Explorer 1 satellite over the years 1981-1984. The quantitative properties will be presented. Densities are found to have one behavior with lessor statistical variation below about L=2 and another with much greater variability above that Lshell. Temperatures also have a behavior difference between low and higher L-values. The density ratio He++/H+ is the best behaved with values of about 0.2% that slightly increase with increasing L. Unlike the He+/H+ density ratio that on average decreases with increasing Lvalue, the O+/H+ and O++/H+ density ratios have decreasing values below about L=2 and increasing average ratios at higher L-values. Hydrogen ion temperatures range from about 0.2 eV to several 10s of eV for a few measurements, although the bulk of the observations are of temperatures below 3 eV, again increasing with L-value. The temperature ratios of He+/H+ are tightly ordered around 1.0 except for the middle plasmasphere between L=3.5 and 4.5 where He+ temperatures can be significantly higher. The temperatures of He++, O+, and O++ are consistently higher than H+.

  17. Plasmaspheric H+, He+, He++, O+, and O++ Densities and Temperatures

    Science.gov (United States)

    Gallagher, G. L.; Craven, P. D.; Comfort, R. H.

    2013-01-01

    Thermal plasmaspheric densities and temperatures for five ion species have recently become available, even though these quantities were derived some time ago from the Retarding Ion Mass Spectrometer onboard the Dynamics Explorer 1 satellite over the years 1981-1984. The quantitative properties will be presented. Densities are found to have one behavior with lessor statistical variation below about L=2 and another with much greater variability above that Lshell. Temperatures also have a behavior difference between low and higher L-values. The density ratio He++/H+ is the best behaved with values of about 0.2% that slightly increase with increasing L. Unlike the He+/H+ density ratio that on average decreases with increasing Lvalue, the O+/H+ and O++/H+ density ratios have decreasing values below about L=2 and increasing average ratios at higher L-values. Hydrogen ion temperatures range from about 0.2 eV to several 10s of eV for a few measurements, although the bulk of the observations are of temperatures below 3 eV, again increasing with L-value. The temperature ratios of He+/H+ are tightly ordered around 1.0 except for the middle plasmasphere between L=3.5 and 4.5 where He+ temperatures can be significantly higher. The temperatures of He++, O+, and O++ are consistently higher than H+.

  18. Ultra low frequency waves observed by Double Star TC-1 in the plasmasphere boundary layer

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The characteristic and properties of ULF waves in the plasmasphere boundary layer during two very quiet periods are present. The ULF waves were detected by Double Star TC-1 when the spacecraft passed through the plasmasphere in an outbound and inbound trajectories, respectively. A clear association between the ULF waves and periodic variations of energetic ions fluxes was observed. The ob-servations showed that the wave frequency was higher inside the plasmasphere than outside. The mechanism generating these ULF waves and possible diagnos-ing of the "classical plasmapause" location with the ULF wave were discussed.

  19. Investigating Plasmasphere Location during Relativistic Electron Precipitation Events

    Science.gov (United States)

    Woodger, L. A.; Millan, R. M.; Goldstein, J.; McCarthy, M. P.; Smith, D. M.; Sample, J. G.

    2006-12-01

    The plasmasphere plays a crucial role in the generation of different wave modes and their resonance conditions with radiation belt relativistic electrons. Meredith's (et. al., 2003) statistical study of resonant conditions for >2MeV electrons with EMIC waves found that the majority of these events occur in the vicinity of the plasmpause. The MAXIS and MINIS balloon observations found a distinct class of relativistic electron precipitation occurring at dusk, suggesting EMIC waves as a possible precipitation mechanism. We investigate the location of these relativistic electron precipitation events with respect to the plasmapause using data from IMAGE EUV, POLAR EFI, and a plasmapause test particle simulation driven by an electric field model with terms representing solar-wind-driven convection and ring-current-ionospheric coupling.

  20. Evolution of chorus emissions into plasmaspheric hiss observed by Van Allen Probes

    Science.gov (United States)

    Zhou, Qinghua; Xiao, Fuliang; Yang, Chang; Liu, Si; He, Yihua; Wygant, J. R.; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.

    2016-05-01

    The two classes of whistler mode waves (chorus and hiss) play different roles in the dynamics of radiation belt energetic electrons. Chorus can efficiently accelerate energetic electrons, and hiss is responsible for the loss of energetic electrons. Previous studies have proposed that chorus is the source of plasmaspheric hiss, but this still requires an observational confirmation because the previously observed chorus and hiss emissions were not in the same frequency range in the same time. Here we report simultaneous observations form Van Allen Probes that chorus and hiss emissions occurred in the same range ˜300-1500 Hz with the peak wave power density about 10-5 nT2/Hz during a weak storm on 3 July 2014. Chorus emissions propagate in a broad region outside the plasmapause. Meanwhile, hiss emissions are confined inside the plasmasphere, with a higher intensity and a broader area at a lower frequency. A sum of bi-Maxwellian distribution is used to model the observed anisotropic electron distributions and to evaluate the instability of waves. A three-dimensional ray tracing simulation shows that a portion of chorus emission outside the plasmasphere can propagate into the plasmasphere and evolve into plasmaspheric hiss. Moreover, hiss waves below 1 kHz are more intense and propagate over a broader area than those above 1 kHz, consistent with the observation. The current results can explain distributions of the observed hiss emission and provide a further support for the mechanism of evolution of chorus into hiss emissions.

  1. A two-dimensional model of the plasmasphere - Refilling time constants

    Science.gov (United States)

    Rasmussen, Craig E.; Guiter, Steven M.; Thomas, Steven G.

    1993-01-01

    A 2D model of the plasmasphere has been developed to study the temporal evolution of plasma density in the equatorial plane of the magnetosphere. This model includes the supply and loss of hydrogen ions due to ionosphere-magnetosphere coupling as well as the effects of E x B convection. A parametric model describing the required coupling fluxes has been developed which utilizes empirical models of the neutral atmosphere, the ionosphere and the saturated plasmasphere. The plasmaspheric model has been used to examine the time it takes for the plasmasphere to refill after it has been depleted by a magnetic storm. The time it takes for the plasmasphere to reach 90 percent of its equilibrium level ranges from 3 days at L = 3 during solar minimum to as high as 100 days at L = 5 during solar maximum. Refilling is also dependent on the month of the year, with refilling requiring a longer period of time at solar maximum during June than during December for L greater than 3.2.

  2. Formation of plasmasphere in the non-ideal corotation field

    Science.gov (United States)

    Dumin, Yurii

    It is well-known that the standard model of plasmasphere formation by the combined action of convection and the ideal corotation fields is too simplified and does not describe some important features. One of attempts to improve it was undertaken a few years ago in our paper [1], where we considered generation of the corotation field in the strongly-anisotropic magnetospheric plasma and took into account distortion of this field in high latitudes due to escape of the polarization charges along the open magnetic field lines. In the present report, we further develop the idea of refinement of the corotation field, particularly, by the consideration of the magnetic dipole inclined with respect to the rotation axis. It will be shown that all the above-mentioned improvements result in the more adequate description of the position of plasmapause both in the quiet and disturbed conditions. References: 1. Yu.V. Dumin. The Corotation Field in Collisionless Magnetospheric Plasma and Its Influence on Average Electric Field in the Lower Atmosphere. Advances in Space Research, v.30, p.2209 (2002).

  3. Real-time imaging of density ducts between the plasmasphere and ionosphere

    CERN Document Server

    Loi, Shyeh Tjing; Cairns, Iver H; Menk, Frederick W; Waters, Colin L; Erickson, Philip J; Trott, Cathryn M; Hurley-Walker, Natasha; Morgan, John; Lenc, Emil; Offringa, Andre R; Bell, Martin E; Ekers, Ronald D; Gaensler, B M; Lonsdale, Colin J; Feng, Lu; Hancock, Paul J; Kaplan, David L; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Deshpande, A A; Greenhill, L J; Hazelton, B J; Johnston-Hollitt, M; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Ord, S M; Prabu, T; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Tingay, S J; Wayth, R B; Webster, R L; Williams, A; Williams, C L

    2015-01-01

    Ionization of the Earth's atmosphere by sunlight forms a complex, multi-layered plasma environment within the Earth's magnetosphere, the innermost layers being the ionosphere and plasmasphere. The plasmasphere is believed to be embedded with cylindrical density structures (ducts) aligned along the Earth's magnetic field, but direct evidence for these remains scarce. Here we report the first direct wide-angle observation of an extensive array of field-aligned ducts bridging the upper ionosphere and inner plasmasphere, using a novel ground-based imaging technique. We establish their heights and motions by feature-tracking and parallax analysis. The structures are strikingly organized, appearing as regularly-spaced, alternating tubes of overdensities and underdensities strongly aligned with the Earth's magnetic field. These findings represent the first direct visual evidence for the existence of such structures.

  4. Global MHD modeling of resonant ULF waves: Simulations with and without a plasmasphere

    Science.gov (United States)

    Claudepierre, S. G.; Toffoletto, F. R.; Wiltberger, M.

    2016-01-01

    We investigate the plasmaspheric influence on the resonant mode coupling of magnetospheric ultralow frequency (ULF) waves using the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic (MHD) model. We present results from two different versions of the model, both driven by the same solar wind conditions: one version that contains a plasmasphere (the LFM coupled to the Rice Convection Model, where the Gallagher plasmasphere model is also included) and another that does not (the stand-alone LFM). We find that the inclusion of a cold, dense plasmasphere has a significant impact on the nature of the simulated ULF waves. For example, the inclusion of a plasmasphere leads to a deeper (more earthward) penetration of the compressional (azimuthal) electric field fluctuations, due to a shift in the location of the wave turning points. Consequently, the locations where the compressional electric field oscillations resonantly couple their energy into local toroidal mode field line resonances also shift earthward. We also find, in both simulations, that higher-frequency compressional (azimuthal) electric field oscillations penetrate deeper than lower frequency oscillations. In addition, the compressional wave mode structure in the simulations is consistent with a radial standing wave oscillation pattern, characteristic of a resonant waveguide. The incorporation of a plasmasphere into the LFM global MHD model represents an advance in the state of the art in regard to ULF wave modeling with such simulations. We offer a brief discussion of the implications for radiation belt modeling techniques that use the electric and magnetic field outputs from global MHD simulations to drive particle dynamics.

  5. Global MHD modeling of resonant ULF waves: Simulations with and without a plasmasphere.

    Science.gov (United States)

    Claudepierre, S G; Toffoletto, F R; Wiltberger, M

    2016-01-01

    We investigate the plasmaspheric influence on the resonant mode coupling of magnetospheric ultralow frequency (ULF) waves using the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic (MHD) model. We present results from two different versions of the model, both driven by the same solar wind conditions: one version that contains a plasmasphere (the LFM coupled to the Rice Convection Model, where the Gallagher plasmasphere model is also included) and another that does not (the stand-alone LFM). We find that the inclusion of a cold, dense plasmasphere has a significant impact on the nature of the simulated ULF waves. For example, the inclusion of a plasmasphere leads to a deeper (more earthward) penetration of the compressional (azimuthal) electric field fluctuations, due to a shift in the location of the wave turning points. Consequently, the locations where the compressional electric field oscillations resonantly couple their energy into local toroidal mode field line resonances also shift earthward. We also find, in both simulations, that higher-frequency compressional (azimuthal) electric field oscillations penetrate deeper than lower frequency oscillations. In addition, the compressional wave mode structure in the simulations is consistent with a radial standing wave oscillation pattern, characteristic of a resonant waveguide. The incorporation of a plasmasphere into the LFM global MHD model represents an advance in the state of the art in regard to ULF wave modeling with such simulations. We offer a brief discussion of the implications for radiation belt modeling techniques that use the electric and magnetic field outputs from global MHD simulations to drive particle dynamics.

  6. Laser radiation frequency conversion in carbon- and cluster-containing plasma plumes under conditions of single and two-color pumping by pulses with a 10-Hz repetition rate

    Science.gov (United States)

    Ganeev, R. A.

    2013-07-01

    This work reviews a series of investigations of different plasma plumes using single- and two-color laser systems that emit femtosecond pulses with a 10-Hz repetition rate. Results of investigation of the resonant enhancement of harmonics in tin plasma with the use of two types of pumps are analyzed, and it is shown that the tuning of the wavelengths of harmonics to ion-resonance levels plays an important role in increasing the conversion efficiency to high-order harmonics of the radiation to be converted. Investigations of different carbon-containing plasma media (carbon nanotubes, graphite, carbon aerogel, etc.) exhibit attractive properties of the nonlinear medium of this type for efficient generation of high-order harmonics. The results of the first experiments on the use of nanoparticles produced directly in the course of laser ablation of metals for increasing the efficiency of harmonics generated in this cluster-containing medium are analyzed. It is shown that new approaches realized in these investigations give hope that the nonlinear optical response of plasma media in the far-ultraviolet range can be further increased.

  7. Solar Coronal Plumes

    Directory of Open Access Journals (Sweden)

    Giannina Poletto

    2015-12-01

    Full Text Available Polar plumes are thin long ray-like structures that project beyond the limb of the Sun polar regions, maintaining their identity over distances of several solar radii. Plumes have been first observed in white-light (WL images of the Sun, but, with the advent of the space era, they have been identified also in X-ray and UV wavelengths (XUV and, possibly, even in in situ data. This review traces the history of plumes, from the time they have been first imaged, to the complex means by which nowadays we attempt to reconstruct their 3-D structure. Spectroscopic techniques allowed us also to infer the physical parameters of plumes and estimate their electron and kinetic temperatures and their densities. However, perhaps the most interesting problem we need to solve is the role they cover in the solar wind origin and acceleration: Does the solar wind emanate from plumes or from the ambient coronal hole wherein they are embedded? Do plumes have a role in solar wind acceleration and mass loading? Answers to these questions are still somewhat ambiguous and theoretical modeling does not provide definite answers either. Recent data, with an unprecedented high spatial and temporal resolution, provide new information on the fine structure of plumes, their temporal evolution and relationship with other transient phenomena that may shed further light on these elusive features.

  8. Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss. 1: Diffusion coefficients and timescales

    Science.gov (United States)

    Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Lyons, L. R.

    1994-01-01

    Protons that are convected into the inner magnetosphere in response to enhanced magnetic activity can resonate with ducted plasmaspheric hiss in the outer plasmasphere via an anomalous Doppler-shifted cyclotron resonance. Plasmaspheric hiss is a right-hand-polarized electromagnetic emission that is observed to fill the plasmasphere on a routine basis. When plasmaspheric hiss is confined within field-aligned ducts or guided along density gradients, wave normal angles remain largely below 45 deg. This allows resonant interactions with ions at typical ring current and radiation belt energies to take place. Such field-aligned ducts have been observed both within the plasmasphere and in regions outside of the plasmasphere. Wave intensities are estimated using statistical information from studies of detached plasma regions. Diffusion coefficients are presented for a range of L shells and proton energies for a fixed wave distribution. Harmonic resonances in the range N = +/-100 are considered in order to include interactions between hiss at 100 Hz to 2 kHz frequencies, and protons in the energy range between approximately 10 keV and 1000 keV. Diffusion timescales are estimated to be of the order of tens of days and comparable to or shorter than lifetimes for Coulomb decay and charge exchange losses over most of the energy and spatial ranges of interest.

  9. Chemistry in aircraft plumes

    Energy Technology Data Exchange (ETDEWEB)

    Kraabol, A.G.; Stordal, F.; Knudsen, S. [Norwegian Inst. for Air Research, Kjeller (Norway); Konopka, P. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    An expanding plume model with chemistry has been used to study the chemical conversion of NO{sub x} to reservoir species in aircraft plumes. The heterogeneous conversion of N{sub 2}O{sub 5} to HNO{sub 3}(s) has been investigated when the emissions take place during night-time. The plume from an B747 has been simulated. During a ten-hour calculation the most important reservoir species was HNO{sub 3} for emissions at noon. The heterogeneous reactions had little impact on the chemical loss of NO{sub x} to reservoir species for emissions at night. (author) 4 refs.

  10. Plasmasphere thermal structure as measured by ISEE-1 and DE-1

    Science.gov (United States)

    Comfort, R. H.

    Characteristics of plasmaspheric ion thermal structure are presented from a statistical survey of low-energy of ion measurements made by the retarding ion mass spectrometer (RIMS) on the DE-1 satellite. Morning and evening results are compared to illustrate diurnal trends. Typical day side temperature range from about 4000 K in the inner plasmasphere to over 10,000 K in the outer plasmasphere, while corresponding evening side temperatures range from near 2000 K to over 10,000 K. Magnetic activity is found to affect the morning and evening sides somewhat differently. Temperatures are found to remain constant or increase with altitude along magnetic field lines, depending on local time and L shell. Thermal equilibrium between H(+) and He(+) prevails to a high degree throughout the plasmasphere. Ion temperatures from the Plasma Composition Experiment (PCE) on ISEE-1 are generally consistent with those from DE-1/RIMS, but are lower and tend to indicate more large scale structure on the day side.

  11. Observations of a Pc5 global (cavity/waveguide) mode outside the plasmasphere by THEMIS

    DEFF Research Database (Denmark)

    Hartinger, Michael; Angelopoulos, Vassilis; Moldwin, Mark B.

    2012-01-01

    Standing fast mode waves known as global modes, or cavity/waveguide modes, have been extensively studied as a potential driver of monochromatic shear Alfven waves in the Earth's magnetosphere via the field line resonance (FLR) mechanism. However, their existence outside of the plasmasphere remain...

  12. Plume Measurement System (PLUMES) Calibration Experiment

    Science.gov (United States)

    1994-08-01

    Atle Lohrmann SonTek, Inc. 7940 Silverton Avenue, No. 105 San Diego, California 92126 and Craig Huhta JIMAR University of Hawaii, Honolulu, Hawaii 96822...Measurement System (PLUMES) Calibration Experiment by Age Lohrmann SonTek, Inc. 7940 Silverton Avenue, No. 105 San Diego, CA 92126 Craig Huhta JIMAR...PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) &. PERFORMING ORGANIZATION SonTek, Inc., 7940 Silverton Avenue, No. 105, San Diego, CA 92126 REPORT NUMBER

  13. Simultaneous disappearances of plasmaspheric hiss, exohiss, and chorus waves triggered by a sudden decrease in solar wind dynamic pressure

    Science.gov (United States)

    Liu, Nigang; Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.; Funsten, H. O.; Wygant, J. R.

    2017-01-01

    Magnetospheric whistler mode waves are of great importance in the radiation belt electron dynamics. Here on the basis of the analysis of a rare event with the simultaneous disappearances of whistler mode plasmaspheric hiss, exohiss, and chorus triggered by a sudden decrease in the solar wind dynamic pressure, we provide evidences for the following physical scenarios: (1) nonlinear generation of chorus controlled by the geomagnetic field inhomogeneity, (2) origination of plasmaspheric hiss from chorus, and (3) leakage of plasmaspheric hiss into exohiss. Following the reduction of the solar wind dynamic pressure, the dayside geomagnetic field configuration with the enhanced inhomogeneity became unfavorable for the generation of chorus, and the quenching of chorus directly caused the disappearances of plasmaspheric hiss and then exohiss.

  14. Martian Atmospheric Plumes: Behavior, Detectability and Plume Tracing

    Science.gov (United States)

    Banfield, Don; Mischna, M.; Sykes, R.; Dissly, R.

    2013-10-01

    We will present our recent work simulating neutrally buoyant plumes in the martian atmosphere. This work is primarily directed at understanding the behavior of discrete plumes of biogenic tracer gases, and thus increasing our understanding of their detectability (both from orbit and from in situ measurements), and finally how to use the plumes to identify their precise source locations. We have modeled the detailed behavior of martian atmospheric plumes using MarsWRF for the atmospheric dynamics and SCIPUFF (a terrestrial state of the art plume modeling code that we have modified to represent martian conditions) for the plume dynamics. This combination of tools allows us to accurately simulate plumes not only from a regional scale from which an orbital observing platform would witness the plume, but also from an in situ perspective, with the instantaneous concentration variations that a turbulent flow would present to a point sampler in situ instrument. Our initial work has focused on the detectability of discrete plumes from an orbital perspective and we will present those results for a variety of notional orbital trace gas detection instruments. We have also begun simulating the behavior of the plumes from the perspective of a sampler on a rover within the martian atmospheric boundary layer. The detectability of plumes within the boundary layer has a very strong dependence on the atmospheric stability, with plume concentrations increasing by a factor of 10-1000 during nighttime when compared to daytime. In the equatorial regions of the planet where we have simulated plumes, the diurnal tidal “clocking” of the winds is strongly evident in the plume trail, which similarly “clocks” around its source. This behavior, combined with the strong diurnal concentration variations suggests that a rover hunting a plume source would be well suited to approach it from a particular azimuth (downwind at night) to maximize detectability of the plume and the ability to

  15. Determinations of ionosphere and plasmasphere electron content for an African chain of GPS stations

    Science.gov (United States)

    Mazzella, Andrew J., Jr.; Bosco Habarulema, John; Yizengaw, Endawoke

    2017-05-01

    The confluence of recent instrumentation deployments in Africa with developments for the determination of plasmasphere electron content using Global Positioning System (GPS) receivers has provided new opportunities for investigations in that region. This investigation, using a selected chain of GPS stations, extends the method (SCORPION) previously applied to a chain of GPS stations in North America in order to separate the ionosphere and plasmasphere contributions to the total electron content (TEC) during a day (24 July) in 2011. The results span latitudes from the southern tip of Africa, across the Equator, to the southern Arabian Peninsula, providing a continuous latitudinal profile for both the ionosphere and plasmasphere during this day.The peak diurnal vertical ionosphere electron content (IEC) increases from about 14 TEC units (1 TEC unit = 1016 electrons m-2) at the southernmost station to about 32 TEC units near the geographic equator, then decreases to about 28 TEC units at the Arabian Peninsula. The peak diurnal slant plasmasphere electron content (PEC) varies between about 4 and 7 TEC units among the stations, with a local latitudinal profile that is significantly influenced by the viewing geometry at the station location, relative to the magnetic field configuration. In contrast, the peak vertical PEC varies between about 1 and 6 TEC units among the stations, with a more uniform latitudinal variation.Comparisons to other GPS data analyses are also presented for TEC, indicating the influence of the PEC on the determination of latitudinal TEC variations and also on the absolute TEC levels, by inducing an overestimate of the receiver bias. The derived TEC latitudinal profiles, in comparison to global map profiles, tend to differ from the map results only about as much as the map results differ among themselves. A combination of ionosonde IEC and alternative GPS TEC measurements, which in principle permits a PEC determination through their difference, was

  16. Influence of bubble size, diffuser width, and flow rate on the integral behavior of bubble plumes

    Science.gov (United States)

    Fraga, Bruño.; Stoesser, Thorsten

    2016-06-01

    A large-eddy simulation based Eulerian-Lagrangian model is employed to quantify the impact of bubble size, diffuser diameter, and gas flow rate on integral properties of bubble plumes, such as the plume's width, centerline velocity, and mass flux. Calculated quantities are compared with experimental data and integral model predictions. Furthermore, the LES data were used to assess the behavior of the entrainment coefficient, the momentum amplification factor, and the bubble-to-momentum spread ratio. It is found that bubble plumes with constant bubble size and smaller diameter behave in accordance with integral plume models. Plumes comprising larger and non-uniform bubble sizes appear to deviate from past observations and model predictions. In multi-diameter bubble plumes, a bubble self-organisation takes place, i.e., small bubbles cluster in the center of the plume whilst large bubbles are found at the periphery of the plume. Multi-diameter bubble plumes also feature a greater entrainment rate than single-size bubble plumes, as well as a higher spread ratio and lower turbulent momentum rate. Once the plume is fully established, the size of the diffuser does not appear to affect integral properties of bubble plumes. However, plume development is affected by the diffuser width, as larger release areas lead to a delayed asymptotic behavior of the plume and consequently to a lower entrainment and higher spread ratio. Finally, the effect of the gas flow rate on the integral plume is studied and is deemed very relevant with regards to most integral plume properties and coefficients. This effect is already fairly well described by integral plume models.

  17. Unsteady turbulent buoyant plumes

    CERN Document Server

    Woodhouse, Mark J; Hogg, Andrew J

    2015-01-01

    We model the unsteady evolution of turbulent buoyant plumes following temporal changes to the source conditions. The integral model is derived from radial integration of the governing equations expressing the conservation of mass, axial momentum and buoyancy. The non-uniform radial profiles of the axial velocity and density deficit in the plume are explicitly described by shape factors in the integral equations; the commonly-assumed top-hat profiles lead to shape factors equal to unity. The resultant model is hyperbolic when the momentum shape factor, determined from the radial profile of the mean axial velocity, differs from unity. The solutions of the model when source conditions are maintained at constant values retain the form of the well-established steady plume solutions. We demonstrate that the inclusion of a momentum shape factor that differs from unity leads to a well-posed integral model. Therefore, our model does not exhibit the mathematical pathologies that appear in previously proposed unsteady i...

  18. Plumes Do Not Exist

    Science.gov (United States)

    Hamilton, W. B.; Anderson, D. L.; Foulger, G. R.; Winterer, E. L.

    Hypothetical plumes from the deep mantle are widely assumed to provide an abso- lute hotspot reference frame, inaugurate rifting, drive plates, and profoundly influence magmatic and tectonic evolution of oceans and continents. Many papers on local to global tectonics, magmatism, and geochemistry invoke plumes, and assign to the man- tle whatever properties, dynamics, and composition are needed to enable them. The fixed-plume concept arose from the Emperor-Hawaii seamount-and-island province, the 45 Ma inflection in which was assumed to record a 60-degree change in direction by the Pacific plate. Paleomagnetic latitudes and smooth Pacific spreading patterns show that such a change did not occur. Other Pacific chains once assumed to be syn- chronous with, and Euler-parallel to, Hawaii have proved to be neither. Thermal and physical properties of Hawaiian lithosphere falsify plume predictions. Rationales for fixed hotspots elsewhere also have become untenable as databases enlarged. Astheno- sphere is everywhere near solidus temperature, so buoyant melt does not require a local heat source but, rather, needs a thin roof or crack or tensional setting for egress. MORB and ocean-island basalt (OIB) broadly intergrade in composition, but MORB typically is richer in refractory elements and their radiogenic daughters, whereas OIB commonly is richer in fusible elements and their daughters. MORB and OIB contrasts are required by melt behavior and do not indicate unlike source reservoirs. MORB melts rise, with minimal reaction, through hot asthenosphere, whereas OIB melts re- act, and thereby lose substance, by crystallizing refractories and retaining and assim- ilating subordinate fusibles, with thick, cool lithosphere and crust. There is no need for hypotheses involving chaotic plume behavior or thousands of km of lateral flow of plume material, nor for postulates of SprimitiveT lower mantle contrary to cos- & cedil;mological and thermodynamic considerations. Plume

  19. Where Plumes Live

    Science.gov (United States)

    King, S. D.

    2004-12-01

    From the perspective of fluid dynamics, `Plumes or not?' might be the wrong question. Let me begin by defining a few terms. Plume with a `P' is the well-known thermal structure with thin (order 100 km) tail and large, bulbous head that originates at the core-mantle boundary. The thin tail/large, bulbous-head morphology has been generated in a number of laboratory and numerical experiments. It can be seen, for example, on the cover of the famous fluid dynamics text by Batchelor. There is a clearly-defined range of parameters for which this structure is the preferred solution for instabilities arising from a bottom boundary layer in a convecting fluid. For example, a strong temperature-dependent rheology is needed. By contrast, plume with a `p' is any cylindrical or quasi-cylindrical instability originating from a thermal (or thermo-chemical) boundary layer. In fluid dynamics plume is sometimes used interchangeable with jet. Unless there is a very small temperature drop across the core-mantle boundary or a rather remarkable balance between temperature and composition at the base of the mantle, there are almost certainly plumes. (Note the little p.) Are these plumes the thermal structures with thin (order 100 km) tails and large bulbous heads or could they be broad, hot regions such as the degree 2 pattern seen in global seismic tomography images of the lower mantle, or the disconnected droplets seen in chaotic convection? To study this question, I will present a sequence of numerical `experiments' that illustrate the morphology of instabilities from a basal thermal boundary layer, i.e., plumes. Some of the aspects I will present include: spherical geometry, temperature-and pressure-dependence of rheology, internal heating, pressure-dependent coefficient of thermal expansion, variable coefficient of thermal diffusivity, phase transformations, and compositional layering at the base of the mantle. The goal is to map out the parameters and conditions where Plumes live

  20. Dilution in Transition Zone between Rising Plumes and Surface Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben

    2004-01-01

    The papers presents some physical experiments with the dilution of sea outfall plumes with emphasize on the transition zone where the relative fast flowing vertical plume turns to a horizontal surface plume following the slow sea surface currents. The experiments show that a considerable dilution...

  1. The plasmasphere during a space weather event: first results from the PLASMON project

    Directory of Open Access Journals (Sweden)

    Reda Jan

    2013-06-01

    Full Text Available The results of the first 18 months of the PLASMON project are presented. We have extended our three, existing ground-based measuring networks, AWDANet (VLF/whistlers, EMMA/SANSA (ULF/FLRs, and AARDDVARK (VLF/perturbations on transmitters’ signal, by three, eight, and four new stations, respectively. The extended networks will allow us to achieve the four major scientific goals, the automatic retrieval of equatorial electron densities and density profiles of the plasmasphere by whistler inversion, the retrieval of equatorial plasma mass densities by EMMA and SANSA from FLRs, developing a new, data assimilative model of plasmasphere and validating the model predictions through comparison of modeled REP losses with measured data by AARDDVARK network. The first results on each of the four objectives are presented through a case study on a space weather event, a dual storm sudden commencement which occurred on August 3 and 4, 2010.

  2. Plasmaspheric electron densities: the importance in modelling radiation belts and in SSA operation

    Science.gov (United States)

    Lichtenberger, János; Jorgensen, Anders; Koronczay, Dávid; Ferencz, Csaba; Hamar, Dániel; Steinbach, Péter; Clilverd, Mark; Rodger, Craig; Juhász, Lilla; Sannikov, Dmitry; Cherneva, Nina

    2016-04-01

    The Automatic Whistler Detector and Analyzer Network (AWDANet, Lichtenberger et al., J. Geophys. Res., 113, 2008, A12201, doi:10.1029/2008JA013467) is able to detect and analyze whistlers in quasi-realtime and can provide equatorial electron density data. The plasmaspheric electron densities are key parameters for plasmasphere models in Space Weather related investigations, particularly in modeling charged particle accelerations and losses in Radiation Belts. The global AWDANet detects millions of whistlers in a year. The network operates since early 2002 with automatic whistler detector capability and it has been recently completed with automatic analyzer capability in PLASMON (http://plasmon.elte.hu, Lichtenberger et al., Space Weather Space Clim. 3 2013, A23 DOI: 10.1051/swsc/2013045.) Eu FP7-Space project. It is based on a recently developed whistler inversion model (Lichtenberger, J. J. Geophys. Res., 114, 2009, A07222, doi:10.1029/2008JA013799), that opened the way for an automated process of whistler analysis, not only for single whistler events but for complex analysis of multiple-path propagation whistler groups. The network operates in quasi real-time mode since mid-2014, fifteen stations provide equatorial electron densities that are used as inputs for a data assimilative plasmasphere model but they can also be used directly in space weather research and models. We have started to process the archive data collected by AWDANet stations since 2002 and in this paper we present the results of quasi-real-time and off-line runs processing whistlers from quiet and disturb periods. The equatorial electron densities obtained by whistler inversion are fed into the assimilative model of the plasmasphere providing a global view of the region for processed the periods

  3. Quantitative Simulation of a Magnetospheric Substorm. 3. Plasmaspheric Electric Fields and Evolution of the Plasmapause.

    Science.gov (United States)

    1980-01-25

    plasmaspheric electric fields during magnetically disturbed periods are based on incoherent scatter radar results fromn St. Santin [ Testud et al., 1975...Millstone Hill radar results showing westward F-region ion drifts of almost 200 m/sec in the afternoon sector on 14 May, 1969. Testud et al. [1975...electrojet (AE) index. Testud et al. [1975] and Blanc et al. £1977] have both presented St. Santin backscatter measurements that show westward and

  4. Non-steady-state transport of superthermal electrons in the plasmasphere

    Science.gov (United States)

    Khazanov, George V.; Liemohn, Michael W.; Gombosi, Tamas I.; Nagy, Andrew F.

    1993-01-01

    Numerical solutions to the time-dependent kinetic equation, which describes the transport of superthermal electrons in the splasmasphere between the two conjugate ionospheres, are presented. The model calculates the distribution function as a function of time, field-aligned distance, energy, and pitch-angle. The processes of refilling, depleting, and establishing steady-state conditions of superthermal electrons in the plasmasphere are discussed.

  5. Turbulent buoyant jets and plumes

    CERN Document Server

    Rodi, Wolfgang

    The Science & Applications of Heat and Mass Transfer: Reports, Reviews, & Computer Programs, Volume 6: Turbulent Buoyant Jets and Plumes focuses on the formation, properties, characteristics, and reactions of turbulent jets and plumes. The selection first offers information on the mechanics of turbulent buoyant jets and plumes and turbulent buoyant jets in shallow fluid layers. Discussions focus on submerged buoyant jets into shallow fluid, horizontal surface or interface jets into shallow layers, fundamental considerations, and turbulent buoyant jets (forced plumes). The manuscript then exami

  6. On predicting mantle mushroom plumes

    Directory of Open Access Journals (Sweden)

    Ka-Kheng Tan

    2011-04-01

    Top cooling may produce plunging plumes of diameter of 585 km and at least 195 Myr old. The number of cold plumes is estimated to be 569, which has not been observed by seismic tomography or as cold spots. The cold plunging plumes may overwhelm and entrap some of the hot rising plumes from CMB, so that together they may settle in the transition zone.

  7. Global-scale coherence modulation of radiation-belt electron loss from plasmaspheric hiss.

    Science.gov (United States)

    Breneman, A W; Halford, A; Millan, R; McCarthy, M; Fennell, J; Sample, J; Woodger, L; Hospodarsky, G; Wygant, J R; Cattell, C A; Goldstein, J; Malaspina, D; Kletzing, C A

    2015-07-09

    Over 40 years ago it was suggested that electron loss in the region of the radiation belts that overlaps with the region of high plasma density called the plasmasphere, within four to five Earth radii, arises largely from interaction with an electromagnetic plasma wave called plasmaspheric hiss. This interaction strongly influences the evolution of the radiation belts during a geomagnetic storm, and over the course of many hours to days helps to return the radiation-belt structure to its 'quiet' pre-storm configuration. Observations have shown that the long-term electron-loss rate is consistent with this theory but the temporal and spatial dynamics of the loss process remain to be directly verified. Here we report simultaneous measurements of structured radiation-belt electron losses and the hiss phenomenon that causes the losses. Losses were observed in the form of bremsstrahlung X-rays generated by hiss-scattered electrons colliding with the Earth's atmosphere after removal from the radiation belts. Our results show that changes of up to an order of magnitude in the dynamics of electron loss arising from hiss occur on timescales as short as one to twenty minutes, in association with modulations in plasma density and magnetic field. Furthermore, these loss dynamics are coherent with hiss dynamics on spatial scales comparable to the size of the plasmasphere. This nearly global-scale coherence was not predicted and may affect the short-term evolution of the radiation belts during active times.

  8. Data assimilation of plasmasphere and upper ionosphere using COSMIC/GPS slant TEC measurements

    Science.gov (United States)

    Wu, M. J.; Guo, P.; Xu, T. L.; Fu, N. F.; Xu, X. S.; Jin, H. L.; Hu, X. G.

    2015-11-01

    Increasing total electron content (TEC) measurements from the low Earth orbiting satellites to Global Positioning System satellites flourish the exploration of the ionosphere and plasmasphere for decades. This paper indicates a method that 3-D Var is applied to assimilate precise orbit determination antenna TEC measurements of Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites into the background global core plasma model (GCPM). The slant TEC data archived in the COSMIC Data Analysis and Archive Center from 500 km to 20,200 km are used to reconstruct a new electron density model. This model has a temporal resolution of 2 h and spatial resolutions of 2.5° in geomagnetic latitude, 5° in longitude, 50 km in the upper ionosphere, and several hundred kilometers in the plasmasphere. Preliminary results show that the data assimilation modifies the initial GCPM forecast to be better coincident with actual COSMIC measurements in internal quality check. Furthermore, independent validation with upper ionosphere-retrieved electron density and TEC of global ionosphere maps implies a reasonable improvement in the estimation of plasmaspheric electron density after the assimilation.

  9. Simulation of field-aligned H+ and He+ dynamics during late-stage plasmasphere refilling

    Directory of Open Access Journals (Sweden)

    J. A. Fedder

    2008-06-01

    Full Text Available The refilling of the plasmasphere for 3≤L≤4 following a model storm is simulated over long times (days using the NRL ionosphere code SAMI2 (Sami2 is Another Model of the Ionosphere. Refilling is dependent on the supply of topside H+ and He+ ions with the result that H+ refilling rates decrease and He+ refilling rates generally increase with increasing F10.7 index. Both early- and late-stage refilling are affected by net ion flows from the warmer to the colder geomagnetic hemisphere. When these flows are strong, the ability of the "winter helium bulge" to increase He+ refilling rates is suppressed. When neutral winds are not included, refilling rates fall, typically by a factor of two. In most cases, late-stage He+ refilling is proportional to H+ refilling, with typical He+/H+ density ratios of 2% for solar minimum and 10% for solar maximum. For high values of F10.7, He+ refilling exhibits a strong diurnal variation so that the He+/H+ density ratio varies by as much as a factor of two during late-stage refilling. Finally if the plasmasphere is left undisturbed, the H+ density can refill for as long as five weeks at L=3 and ten weeks at L=4, with saturation densities nearly an order of magnitude greater than typical observed densities. This confirms that the plasmasphere at these L values rarely obtains saturation.

  10. Thermal plumes in ventilated rooms

    DEFF Research Database (Denmark)

    Kofoed, Peter; Nielsen, Peter V.

    1990-01-01

    The design of a displacement ventilation system involves determination of the flow rate in the thermal plumes. The flow rate in the plumes and the vertical temperature gradient influence each other, and they are influenced by many factors. This paper shows some descriptions of these effects. Free...... to be the only possible approach to obtain the volume flow in: thermal plumes in ventilated rooms....

  11. Kalman filter-based algorithms for monitoring the ionosphere and plasmasphere with GPS in near-real time

    Science.gov (United States)

    Anghel, Adela; Carrano, Charles; Komjathy, Attila; Astilean, Adina; Letia, Tiberiu

    2009-01-01

    Data collected from a GPS receiver located at low latitudes in the American sector are used to investigate the performance of the WinTEC algorithm [Anghel et al., 2008a, Kalman filter-based algorithm for near realtime monitoring of the ionosphere using dual frequency GPS data. GPS Solutions, accepted for publication; for different ionospheric modeling techniques: the single-shell linear, quadratic, and cubic approaches, and the multi-shell linear approach. Our results indicate that the quadratic and cubic approaches perform much better than the single-shell and multi-shell linear approaches in terms of post-fit residuals. The performance of the algorithm for the cubic approach is then further tested by comparing the vertical TEC predicted by WinTEC and USTEC [Spencer et al., 2004. Ionospheric data assimilation methods for geodetic applications. In: Proceedings of IEEE PLANS, Monterey, CA, 26-29 April, pp. 510-517] at five North American stations. In addition, since the GPS-derived total electron content (TEC) contains contributions from both ionospheric and plasmaspheric sections of the GPS ray paths, in an effort to improve the accuracy of the TEC retrievals, a new data assimilation module that uses background information from an empirical plasmaspheric model [Gallagher et al., 1988. An empirical model of the Earth's plasmasphere. Advances in Space Research 8, (8)15-(8)24] has been incorporated into the WinTEC algorithm. The new Kalman filter-based algorithm estimates both the ionospheric and plasmaspheric electron contents, the combined satellite and receiver biases, and the estimation error covariance matrix, in a single-site or network solution. To evaluate the effect of the plasmaspheric component on the estimated biases and total TEC and to assess the performance of the newly developed algorithm, we compare the WinTEC results, with and without the plasmaspheric term included, at three GPS receivers located at different latitudes in the American sector, during

  12. A case for mantle plumes

    Institute of Scientific and Technical Information of China (English)

    Geoffrey F. Davies

    2005-01-01

    The existence of at least several plumes in the Earth's mantle can be inferred with few assumptions from well-established observations. As well, thermal mantle plumes can be predicted from well-established and quantified fluid dynamics and a plausible assumption about the Earth's early thermal state. Some additional important observations, especially of flood basalts and rift-related magmatism, have been shown to be plausibly consistent with the physical theory. Recent claims to have detected plumes using seismic tomography may comprise the most direct evidence for plumes, but plume tails are likely to be difficult to resolve definitively and the claims need to be well tested. Although significant questions remain about its viability, the plume hypothesis thus seems to be well worth continued investigation. Nevertheless there are many non-plate-related magmatic phenomena whose association with plumes is unclear or unlikely. Compositional buoyancy has recently been shown potentially to substantially complicate the dynamics of plumes, and this may lead to explanations for a wider range of phenomena, including "headless" hotspot tracks, than purely thermal plumes.

  13. Mantle plumes and continental tectonics.

    Science.gov (United States)

    Hill, R I; Campbell, I H; Davies, G F; Griffiths, R W

    1992-04-10

    Mantle plumes and plate tectonics, the result of two distinct modes of convection within the Earth, operate largely independently. Although plumes are secondary in terms of heat transport, they have probably played an important role in continental geology. A new plume starts with a large spherical head that can cause uplift and flood basalt volcanism, and may be responsible for regional-scale metamorphism or crustal melting and varying amounts of crustal extension. Plume heads are followed by narrow tails that give rise to the familiar hot-spot tracks. The cumulative effect of processes associated with tail volcanism may also significantly affect continental crust.

  14. Terrestrial Plume Impingement Testbed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Masten Space Systems proposes to create a terrestrial plume impingement testbed for generating novel datasets for extraterrestrial robotic missions. This testbed...

  15. Determination of global plasmaspheric electron density profile by tomographic approach using omega signals and ray tracing

    Science.gov (United States)

    Kimura, I.; Kasahara, Y.; Oya, H.

    2001-07-01

    It has been necessary requirements to determine the global electron density distribution in the plasmasphere with time resolutions, of less than a day. We have provided solutions to this requirement using the wave normal directions, delay time of Omega signals and the in situ electron density observed on-board the Japanese satellite Akebono (Sawada et al., Journal of Geophysical Research 98(11) (1993) 267, Kimura et al., Advance Space Research 15(2) (1995) 103, Advance Space Research 18(6) (1996) 279, Journal of Atmospheric and Solar-Terrestrial Physics 59 (1997) 1569). The present paper is intended to review our earlier studies.

  16. 3D Reconfigurable NoC Multiprocessor Portable Sounder for Plasmaspheric Studies

    Science.gov (United States)

    Dekoulis, George

    2016-07-01

    The paper describes the development of a prototype imaging sounder for studying the irregularities of the ionospheric plasma. Cutting edge three-dimensional reconfigurable logic has been implemented allowing highly-intensive scientific calculations to be performed in hardware. The new parallel processing algorithms implemented offer a significant amount of performance improvement in the range of 80% compared to existing digital sounder implementations. The current system configuration is taking into consideration the modern scientific needs for portability during scientific campaigns. The prototype acts as a digital signal processing experimentation platform for future larger-scale digital sounder instrumentations for measuring complex planetary plasmaspheric environments.

  17. Effects of plasmaspheric ion heating due to ionospheric and magnetospheric sources

    Science.gov (United States)

    Comfort, Richard H.

    1996-01-01

    In an initial study, the He(+) observations from the Retarding Ion Mass Spectrometer on Dynamics Explorer 1 (RIMS/DE 1) was examined for more than 120 transits of the plasmasphere in the fall of 1981. The He(+) to H(+) ratio was determined as it varied spatially over portions of the DE 1 orbit, and its variation with solar and magnetic activities and with local time, focusing specifically on the inner plasmasphere. These variations were compared along the L = 2 field line with calculations made by the Field Line Interhemispheric Plasma (FLIP) code. In a recently submitted paper, the He(+) to H(+) density ratio was examined for all the available data from 1981 to 1984 from the RIMS on DE 1. There are two basic characteristics of the ratio: one is that the ratio decreases with radial distance in the plasmasphere, and the other is the strong dependence of the density ratio on solar activity. In addition to the He(+)/H(+) ratio research, a phenomenon has been studied in the topside ionosphere which relates to the thermal coupling of the ionosphere to the plasmasphere. There is little or no correlation with magnetic and solar activity here. Another study has been directed toward the relation of plasma properties to the density gradients forming the plasmapause. The study has followed a two-pronged approach. First, the observations have been analyzed to determine what happens to the plasma properties across these boundary layers (density gradients). Second, comparisons were made with FLIP model calculations to determine how well the model is able to treat these conditions. Among the significant lessons learned in these studies are two that bear directly on the direction of future investigations in this area. First, composition cannot be viewed independently of thermal structure. Second, solar and magnetic activity effects are real; but the causal relationship between activity and effects is frequently quite complicated because several different processes appear to be

  18. Dilution of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben; Petersen, Ole

    The purpose of present work is to establish a quantitative description of a surface plume which is valid for the range of density differences occurring in relation to sewage outfalls.......The purpose of present work is to establish a quantitative description of a surface plume which is valid for the range of density differences occurring in relation to sewage outfalls....

  19. Thermal Plumes in Ventilated Rooms

    DEFF Research Database (Denmark)

    Kofoed, Peter; Nielsen, Peter V.

    The design of a displacement ventilation system involves determination of the flow rate in the thermal plumes. The flow rate in the plumes and the vertical temperature gradient influence each other, and they are influenced by many factors. This paper shows some descriptions of these effects....

  20. Atmospheric chemistry in volcanic plumes.

    Science.gov (United States)

    von Glasow, Roland

    2010-04-13

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.

  1. Cluster-cluster clustering

    Science.gov (United States)

    Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C. S.

    1985-01-01

    The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales.

  2. Cluster-cluster clustering

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C.S.

    1985-08-01

    The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales. 30 references.

  3. Orbital Maneuvering Vehicle (OMV) plume and plume effects study

    Science.gov (United States)

    Smith, Sheldon D.

    1991-01-01

    The objective was to characterize the Orbital Maneuvering Vehicle (OMV) propulsion and attitude control system engine exhaust plumes and predict the resultant plume impingement pressure, heat loads, forces, and moments. Detailed description is provided of the OMV gaseous nitrogen (GN2) thruster exhaust plume flow field characteristics calculated with the RAMP2 snd SFPGEN computer codes. Brief descriptions are included of the two models, GN2 thruster characteristics and RAMP2 input data files. The RAMP2 flow field could be recalculated by other organizations using the information presented. The GN2 flow field can be readily used by other organizations who are interested in GN2 plume induced environments which require local flow field properties which can be supplied using the SFPGEN GN2 model.

  4. Plume splitting in pico-second laser-material interaction under the influence of shock wave

    Energy Technology Data Exchange (ETDEWEB)

    Gacek, Sobieslaw [Department of Mechanical Engineering, 2010 H. M. Black Engineering Building Iowa State University, Ames, IA 50011-2161 (United States); Wang Xinwei, E-mail: xwang3@iastate.ed [Department of Mechanical Engineering, 2010 H. M. Black Engineering Building Iowa State University, Ames, IA 50011-2161 (United States)

    2009-09-07

    In this work, molecular dynamics simulations are conducted to study the physics of plume splitting in pico-second laser material interaction in background gas. The velocity distribution shows a clear split into two distinctive components. Detailed atom trajectory track reveals the behavior of atoms within the peaks and uncovers the mechanisms of peak formation. The observed plume velocity splitting emerges from two distinguished parts of the plume. The front peak of the plume is from the faster moving atoms and smaller particles during laser-material ablation. This region experiences strong constraint from the ambient gas and has substantial velocity attenuation. The second (rear) peak of the plume velocity originates from the larger and slower clusters in laser-material ablation. These larger clusters/particles experience very little constraint from the background, but are affected by the relaxation dynamics of plume and appear almost as a standing wave during the evolution. Density splitting only appears at the beginning of laser-material ablation and quickly disappears due to spread-out of the slower moving clusters. It is found that higher ambient pressure and stronger laser fluence favor earlier plume splitting.

  5. Biogeochemistry of landfill leachate plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Kjeldsen, Peter; Bjerg, Poul Løgstrup

    2001-01-01

    is on dissolved organic matter, xenobiotic organic compounds, inorganic macrocomponents as anions and cations, and heavy metals. Laboratory as well as field investigations are included. This review is an up-date of an earlier comprehensive review. The review shows that most leachate contamination plumes...... the behavior of the contaminants in the plume as the leachate migrates away from the landfill. Diverse microbial communities have been identified in leachate plumes and are believed to be responsible for the redox processes. Dissolved organic C in the leachate, although it appears to be only slowly degradable...

  6. Smoke plumes: Emissions and effects

    Science.gov (United States)

    Susan O' Neill; Shawn Urbanski; Scott Goodrick; Sim Larkin

    2017-01-01

    Smoke can manifest itself as a towering plume rising against the clear blue sky-or as a vast swath of thick haze, with fingers that settle into valleys overnight. It comes in many forms and colors, from fluffy and white to thick and black. Smoke plumes can rise high into the atmosphere and travel great distances across oceans and continents. Or smoke can remain close...

  7. Equatorial spread F fossil plumes

    Directory of Open Access Journals (Sweden)

    S. L. Ossakow

    2010-11-01

    Full Text Available Behaviour of equatorial spread F (ESF fossil plumes, i.e., ESF plumes that have stopped rising, is examined using the NRL SAMI3/ESF three-dimensional simulation code. We find that fossil bubbles, plasma density depletions associated with fossil plumes, can persist as high-altitude equatorial depletions even while being "blown" by zonal winds. Corresponding airglow-proxy images of fossil plumes, plots of electron density versus longitude and latitude at a constant altitude of 288 km, are shown to partially "fill in" in most cases, beginning with the highest altitude field lines within the plume. Specifically, field lines upon which the E field has fallen entirely to zero are affected and only the low altitude (≤600 km portion if each field line fills in. This suggests that it should be possible to observe a bubble at high altitude on a field line for which the corresponding airglow image no longer shows a depletion. In all cases ESF plumes stop rising when the flux-tube-integrated ion mass density inside the upper edge of the bubble is equal to that of the nearby background, further supporting the result of Krall et al. (2010b.

  8. Impact of the dipole tilt angle on the ionospheric plasma in the outer plasmasphere

    Science.gov (United States)

    Marchaudon, Aurelie; Blelly, Pierre-Louis

    2015-04-01

    We have developed a new interhemispheric 16-moment based ionosphere model. This model describes the field-aligned transport of the multi-species ionospheric plasma (6 ions) from one hemisphere to the other, taking into account source processes at low altitudes (photoionization, chemistry) and coupling with suprathermal electrons. We simulate the convection and corotation transport of closed flux tubes in the outer plasmasphere for tilted/eccentric dipolar magnetic field configuration. We ran the model in solstice and equinox conditions and for two plasmapause boundary conditions: one corresponding to standard conditions with a stagnation point at 4.5 Earth radii (RE) and 15h Magnetic Local Time (MLT) and one corresponding to very quiet conditions with a stagnation point at 6 RE and 15h MLT. For each season/stagnation simulation, the model is run for 30 days before the equinox/solstice date in order to eliminate the transients. The goal is to study the combined effect of the tilt of the magnetic field and the rotation axis on the field-aligned dynamics and overall equilibrium of the subauroral ionosphere. In the classical representation of the plasmasphere, the ionosphere only depends on angular MLT sector. We will show that due to the tilt effect, this view is erroneous and no real dynamic equilibrium is reached, in particular close to the stagnation point where we can observe large day-to-day variations in the ionospheric parameters. Finally, we will present the temperatures anisotropy development along the flux tube for different positions of the stagnation point.

  9. High-order harmonic generation in laser plasma plumes

    CERN Document Server

    Ganeev, Rashid A

    2013-01-01

    This book represents the first comprehensive treatment of high-order harmonic generation in laser-produced plumes, covering the principles, past and present experimental status and important applications. It shows how this method of frequency conversion of laser radiation towards the extreme ultraviolet range matured over the course of multiple studies and demonstrated new approaches in the generation of strong coherent short-wavelength radiation for various applications. Significant discoveries and pioneering contributions of researchers in this field carried out in various laser scientific centers worldwide are included in this first attempt to describe the important findings in this area of nonlinear spectroscopy. "High-Order Harmonic Generation in Laser Plasma Plumes" is a self-contained and unified review of the most recent achievements in the field, such as the application of clusters (fullerenes, nanoparticles, nanotubes) for efficient harmonic generation of ultrashort laser pulses in cluster-containin...

  10. Self-Consistent Model of Magnetospheric Electric Field, Ring Current, Plasmasphere, and Electromagnetic Ion Cyclotron Waves: Initial Results

    Science.gov (United States)

    Gamayunov, K. V.; Khazanov, G. V.; Liemohn, M. W.; Fok, M.-C.; Ridley, A. J.

    2009-01-01

    Further development of our self-consistent model of interacting ring current (RC) ions and electromagnetic ion cyclotron (EMIC) waves is presented. This model incorporates large scale magnetosphere-ionosphere coupling and treats self-consistently not only EMIC waves and RC ions, but also the magnetospheric electric field, RC, and plasmasphere. Initial simulations indicate that the region beyond geostationary orbit should be included in the simulation of the magnetosphere-ionosphere coupling. Additionally, a self-consistent description, based on first principles, of the ionospheric conductance is required. These initial simulations further show that in order to model the EMIC wave distribution and wave spectral properties accurately, the plasmasphere should also be simulated self-consistently, since its fine structure requires as much care as that of the RC. Finally, an effect of the finite time needed to reestablish a new potential pattern throughout the ionosphere and to communicate between the ionosphere and the equatorial magnetosphere cannot be ignored.

  11. Ion energy distributions and densities in the plume of Enceladus

    Science.gov (United States)

    Sakai, Shotaro; Cravens, Thomas E.; Omidi, Nojan; Perry, Mark E.; Waite, J. Hunter

    2016-10-01

    ionization. The origin of the ions in the plume was investigated using two different velocity models. Most ions were created by the interaction with background magnetospheric plasma and by photoionization. INMS and CAPS also detected water cluster ions. We will interpret these observations as a result of ion collisions with neutral water clusters, (H2O)n, originating in the tiger stripe vents as suggested by Tokar et al. (2009). We also estimated the process of generating cluster ions based on the INMS observations. We suggest that the most likely source is reaction of H3O+ with neutral water clusters or dimers such as (H2O)2 formed in the plume vents.

  12. ISEE 1 observations of thermal plasma in the vicinity of the plasmasphere during periods of quieting magnetic activity

    Energy Technology Data Exchange (ETDEWEB)

    Horwitz, J.L.; Baugher, C.R.; Chappell, C.R.; Shelley, E.G.; Young, D.T.; Anderson, R.R.

    1981-11-01

    Thermal (< or approx. =100 electron volts) ion observations made with the plasma composition experiment on ISEE 1 are combined with plasma density profiles obtained from plasma frequency measurements made with the plasma wave experiment to conduct an investigation of thermal plasma behavior in the vicinity of the plasmasphere during periods of quieting magnetic activity. Normally, the principal thermal ion population in the plasmasphere consists of cold (kT< or approx. =1 eV), isotropic distributions with ion species in the order of dominance H/sup +/:He/sup +/:O/sup +/, while outside the plasmapause, the observed E< or approx. =100 eV ion distributions usually are field-aligned in structure, have characteristic energies E< or approx. =10 eV and H/sup +/:O/sup +/He/sup +/ order of dominance in fluxes. During periods in which the magnetic activity quiets, the above two regions are separated by a new region in which, at times, low-energy (approx.1-2 eV) H/sup +/ and He/sup +/ are found flowing along the magnetic field lines. On other occasions following quieting magnetic activity, pancake distributions (peak fluxes at 90/sup 0/ pitch angle) are observed in this region. Other complex distributions have been seen, and these complexities and the limitations of the data coverage preclude a satisfactory simple interpretation. It seems plausible to identify this region as the site of plasmasphere refilling. However, the data presumably also contain evidence of the quiet time rotation of the plasmasphere bulge region into the morning sector.

  13. A case study of storm commencement and recovery plasmaspheric electric fields near L=2.5 at equinox

    Directory of Open Access Journals (Sweden)

    H. F. Balmforth (*

    Full Text Available Data from the VLF Doppler experiment at Faraday, Antarctica (65° S, 64° W are used to study the penetration of the high-latitude convection electric field to lower latitudes during severely disturbed conditions. Alterations of the electric field at L-values within the range 2.0 - 2.7 are studied for two cases at equinox (10 - 12 September 1986 and 1 - 3 May 1986. The recovery of the electric field is found to be approximately an exponential function of time. Values for the equatorial meridional E×B drift velocity, inferred from the data, are used as inputs to a model of the plasmasphere and ionosphere. The model and experimental results are used to investigate the post-storm alteration of ionospheric coupling processes. The magnitude of the effect of ionosphere-plasmasphere coupling fluxes on NmF2 values and the O+-H+ transition height is dependent on the local time of storm commencement, and on the orientation of the electric field. The coupling fluxes appear to have a maximum influence on ionospheric content during the main phase of geomagnetic activity that produces outward motion of plasmaspheric whistler ducts.

  14. Plumes in stellar convection zones

    CERN Document Server

    Zahn, J P

    1999-01-01

    All numerical simulations of compressible convection reveal the presence of strong downwards directed flows. Thanks to helioseismology, such plumes have now been detected also at the top of the solar convection zone, on super- granular scales. Their properties may be crudely described by adopting Taylor's turbulent entrainment hypothesis, whose validity is well established under various conditions. Using this model, one finds that the strong density stratification does not prevent the plumes from traversing the whole convection zone, and that they carry upwards a net energy flux (Rieutord & Zahn 1995). They penetrate to some extent in the adjacent stable region, where they establish a nearly adiabatic stratification. These plumes have a strong impact on the dynamics of stellar convection zones, and they play probably a key role in the dynamo mechanism.

  15. Coastal river plumes: Collisions and coalescence

    Science.gov (United States)

    Warrick, Jonathan A.; Farnsworth, Katherine L.

    2017-02-01

    Plumes of buoyant river water spread in the ocean from river mouths, and these plumes influence water quality, sediment dispersal, primary productivity, and circulation along the world's coasts. Most investigations of river plumes have focused on large rivers in a coastal region, for which the physical spreading of the plume is assumed to be independent from the influence of other buoyant plumes. Here we provide new understanding of the spreading patterns of multiple plumes interacting along simplified coastal settings by investigating: (i) the relative likelihood of plume-to-plume interactions at different settings using geophysical scaling, (ii) the diversity of plume frontal collision types and the effects of these collisions on spreading patterns of plume waters using a two-dimensional hydrodynamic model, and (iii) the fundamental differences in plume spreading patterns between coasts with single and multiple rivers using a three-dimensional hydrodynamic model. Geophysical scaling suggests that coastal margins with numerous small rivers (watershed areas 100,000 km2). When two plume fronts meet, several types of collision attributes were found, including refection, subduction and occlusion. We found that the relative differences in pre-collision plume densities and thicknesses strongly influenced the resulting collision types. The three-dimensional spreading of buoyant plumes was found to be influenced by the presence of additional rivers for all modeled scenarios, including those with and without Coriolis and wind. Combined, these results suggest that plume-to-plume interactions are common phenomena for coastal regions offshore of the world's smaller rivers and for coastal settings with multiple river mouths in close proximity, and that the spreading and fate of river waters in these settings will be strongly influenced by these interactions. We conclude that new investigations are needed to characterize how plumes interact offshore of river mouths to better

  16. Coastal river plumes: Collisions and coalescence

    Science.gov (United States)

    Warrick, Jonathan; Farnsworth, Katherine L

    2017-01-01

    Plumes of buoyant river water spread in the ocean from river mouths, and these plumes influence water quality, sediment dispersal, primary productivity, and circulation along the world’s coasts. Most investigations of river plumes have focused on large rivers in a coastal region, for which the physical spreading of the plume is assumed to be independent from the influence of other buoyant plumes. Here we provide new understanding of the spreading patterns of multiple plumes interacting along simplified coastal settings by investigating: (i) the relative likelihood of plume-to-plume interactions at different settings using geophysical scaling, (ii) the diversity of plume frontal collision types and the effects of these collisions on spreading patterns of plume waters using a two-dimensional hydrodynamic model, and (iii) the fundamental differences in plume spreading patterns between coasts with single and multiple rivers using a three-dimensional hydrodynamic model. Geophysical scaling suggests that coastal margins with numerous small rivers (watershed areas  100,000 km2). When two plume fronts meet, several types of collision attributes were found, including refection, subduction and occlusion. We found that the relative differences in pre-collision plume densities and thicknesses strongly influenced the resulting collision types. The three-dimensional spreading of buoyant plumes was found to be influenced by the presence of additional rivers for all modeled scenarios, including those with and without Coriolis and wind. Combined, these results suggest that plume-to-plume interactions are common phenomena for coastal regions offshore of the world’s smaller rivers and for coastal settings with multiple river mouths in close proximity, and that the spreading and fate of river waters in these settings will be strongly influenced by these interactions. We conclude that new investigations are needed to characterize how plumes interact offshore of river mouths to

  17. Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss. 2. Time evolution of the distribution function

    Science.gov (United States)

    Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Villalon, E.

    1995-11-01

    The evolution of the bounce-averaged ring current/radiation belt proton distribution is simulated during resonant interactions with ducted plasmaspheric hiss. The plasmaspheric hiss is assumed to be generated by ring current electrons and to be damped by the energetic protons. Thus energy is transferred between energetic electrons and protons using the plasmaspheric hiss as a mediary. The problem is not solved self-consistently. During the simulation period, interactions with ring current electrons (not represented in the model) are assumed to maintain the wave amplitudes in the presence of damping by the energetic protons, allowing the wave spectrum to be held fixed. Diffusion coefficients in pitch angle, cross pitch angle/energy, and energy were previously calculated by Kozyra et al. (1994) and are adopted for the present study. The simulation treats the energy range, E>=80 keV, within which the wave diffusion operates on a shorter timescale than other proton loss processes (i.e., Coulomb drag and charge exchange). These other loss processes are not included in the simulation. An interesting result of the simulation is that energy diffusion maximizes at moderate pitch angles near the edge of the atmospheric loss cone. Over the simulation period, diffusion in energy creates an order of magnitude enhancement in the bounce-averaged proton distribution function at moderate pitch angles. The loss cone is nearly empty because scattering of particles at small pitch angles is weak. The bounce-averaged flux distribution, mapped to ionospheric heights, results in elevated locally mirroring proton fluxes. OGO 5 observed order of magnitude enhancements in locally mirroring energetic protons at altitudes between 350 and 1300 km and invariant latitudes between 50° and 60° (Lundblad and Soraas, 1978). The proton distributions were highly anisotropic in pitch angle with nearly empty loss cones. The similarity between the observed distributions and those resulting from this

  18. Full-wave model of D-region upward VLF coupling to whistlers in the plasmasphere

    Science.gov (United States)

    Jacobson, A. R.; Shao, X.; Lay, E. H.

    2012-12-01

    Atmospheric-lightning-to-plasmasphere VLF coupling via whistlers is key to understanding the problem of radiation-belt losses and the slot region. In the lowermost ionosphere, the "D-region" (roughly 60 - 100 km altitude), the coupling occurs between the VLF incident from the "vacuum" below, to the electron whistler capable of transiting upward through the E- and F-regions above. We have modified our successful and data-validated D-region VLF downward-reflection model to predict upward-coupled whistler waveforms recorded on topside satellites. The model has been run in production mode for predicting downward-reflected waveforms recorded at ground stations, but the model's internal calculation also fully describes the "penetrating" solution that merges into the oblique electron whistler. We have begun to test the model against VLF, three-dimensional electric-field recordings from the Vector Electric Field Instrument (VEFI) [Pfaff et al., 2010] on the C/NOFS satellite. VEFI's broadband recording and large on-board memory serendipitously provide an excellent platform for studying lightning whistlers in the plasmasphere. We have already demonstrated [Jacobson et al., 2011] that VEFI is superbly suited for testing transionospheric propagation, in conjunction with the World Wide Lightning Location Network (WWLLN; see www.wwlln.net) to provide groundtruth location/time of the lightning strokes. This poster will describe latest results. Jacobson, A. R., R. H. Holzworth, R. F. Pfaff, and M. P. McCarthy (2011), Study of oblique whistlers in the low-latitude ionosphere, jointly with the C/NOFS satellite and the World-Wide Lightning Location Network, Annales Geophysicae, 29, 851-863. Pfaff, R., D. Rowland, H. Freudenreich, K. Bromund, K. Le, M. Acuna, J. Klenzing, C. Liebrecht, S. Martin, W. J. Burke, N. C. Maynard, D. E. Hunton, P. A. Roddy, J. O. Ballenthin, and G. R. Wilson (2010), Observations of DC electric fields in the low-latitude ionosphere and their variations with

  19. Lidar measurements of plume statistics

    DEFF Research Database (Denmark)

    Ejsing Jørgensen, Hans; Mikkelsen, T.

    1993-01-01

    the source, instantaneous crosswind plume profiles were detected repetitively at high spatial (1.5 m) and temporal (3 sec) intervals by use of a mini LIDAR system. The experiments were accompanied by measurement of the surface-layer mean wind and turbulence quantities by sonic anemometers. On the basis...

  20. Ship exhaust gas plume cooling

    NARCIS (Netherlands)

    Schleijpen, H.M.A.; Neele, P.P.

    2004-01-01

    The exhaust gas plume is an important and sometimes dominating contributor to the infrared signature of ships. Suppression of the infrared ship signatures has been studied by TNO for the Royal Netherlands Navy over considerable time. This study deals with the suppression effects, which can be achiev

  1. Downwelling wind, tides, and estuarine plume dynamics

    Science.gov (United States)

    Lai, Zhigang; Ma, Ronghua; Huang, Mingfen; Chen, Changsheng; Chen, Yong; Xie, Congbin; Beardsley, Robert C.

    2016-06-01

    The estuarine plume dynamics under a downwelling-favorable wind condition were examined in the windy dry season of the Pearl River Estuary (PRE) using the PRE primitive-equation Finite-Volume Community Ocean Model (FVCOM). The wind and tide-driven estuarine circulation had a significant influence on the plume dynamics on both local and remote scales. Specifically, the local effect of downwelling-favorable winds on the plume was similar to the theoretical descriptions of coastal plumes, narrowing the plume width, and setting up a vertically uniform downstream current at the plume edge. Tides tended to reduce these plume responses through local turbulent mixing and advection from upstream regions, resulting in an adjustment of the isohalines in the plume and a weakening of the vertically uniform downstream current. The remote effect of downwelling-favorable winds on the plume was due to the wind-induced estuarine sea surface height (SSH), which strengthened the estuarine circulation and enhanced the plume transport accordingly. Associated with these processes, tide-induced mixing tended to weaken the SSH gradient and thus the estuarine circulation over a remote influence scale. Overall, the typical features of downwelling-favorable wind-driven estuarine plumes revealed in this study enhanced our understanding of the estuarine plume dynamics under downwelling-favorable wind conditions.

  2. Characterization of redox conditions in pollution plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwart, Steven A.

    2000-01-01

    Evalution of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...

  3. Characterization of redox conditions in pollution plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwart, Steven A.

    2000-01-01

    Evalution of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...

  4. Dispersal of the Pearl River plume over continental shelf in summer

    Science.gov (United States)

    Chen, Zhaoyun; Gong, Wenping; Cai, Huayang; Chen, Yunzhen; Zhang, Heng

    2017-07-01

    Satellite images of turbidity were used to study the climatological, monthly, and typical snapshot distributions of the Pearl River plume over the shelf in summer from 2003 to 2016. These images show that the plume spreads offshore over the eastern shelf and is trapped near the coast over the western shelf. Eastward extension of the plume retreats from June to August. Monthly spatial variations of the plume are characterized by eastward spreading, westward spreading, or both. Time series of monthly plume area was quantified by applying the K-mean clustering method to identify the turbid plume water. Decomposition of the 14-year monthly turbidity data by the empirical orthogonal function (EOF) analysis isolated the 1st mode in both the eastward and westward spreading pattern as the time series closely related to the Pearl River discharge, and the 2nd mode with out-of-phase turbidity anomalies over the eastern and western shelves that is associated with the prevailing wind direction. Eight typical plume types were detected from the satellite snapshots. They are characterized by coastal jet, eastward offshore spreading, westward spreading, bidirectional spreading, bulge, isolated patch, offshore branch, and offshore filaments, respectively. Their possible mechanisms are discussed.

  5. Compositional differentiation of Enceladus' plume

    Science.gov (United States)

    Khawaja, N.; Postberg, F.; Schmidt, J.

    2014-04-01

    The Cosmic Dust Analyser (CDA) on board the Cassini spacecraft sampled Enceladus' plume ice particles emanated directly from Enceladus' fractured south polar terrain (SPT), the so-called "Tiger Stripes", during two consecutive flybys (E17 and E18) in 2012. The spacecraft passed through the dense plume with a moderate velocity of ~7.5km/s, horizontally to the SPT with a closest approach (CA) at an altitude of ~75km almost directly over the south pole. In both flybys, spectra were recorded during a time interval of ~ ±3 minutes with respect to the closest approach achieving an average sampling rate of about 0.6 sec-1. We assume that the spacecraft passed through the plume during an interval of about ±60(sec) from the CA. Particles encountered before and after this period are predominately from the E-ring background in which Enceladus is embedded. Most CDA TOF-mass spectra are identified as one of three compositional types: (i) almost pure water (ii) organic rich and (iii) salt rich [2]. A Boxcar Analysis (BCA) is performed from a count database for compositional mapping of the plume along the space-craft trajectory. In BCA, counts of each spectrum type are integrated for a certain interval of time (box size). The integral of counts represents frequencies of compositional types in absolute abundances, which are converted later into proportions. This technique has been proven to be a suitable for inferring the compositional profiles from an earlier flyby (E5) [1]. The inferred compositional profiles show similar trends on E17 and E18. The abundances of different compositional types in the plume clearly differ from the Ering background and imply a compositional differentiation inside the plume. Following up the work of Schmidt et al, 2008 and Postberg et al, 2011 we can link different compositional types to different origins. The E17/E18 results are compared with the E5 flyby in 2008, which yielded the currently best compositional profile [2] but was executed at much

  6. On the great plume debate

    Institute of Scientific and Technical Information of China (English)

    Yaoling Niu

    2005-01-01

    @@ 1 Introductory note Geological processes are ultimately consequences of Earth's thermal evolution. Plate tectonic theory, which explains geological phenomena along plate boundaries, elegantly illustrates this concept. For example, the origin of oceanic plates at ocean ridges, the movement and growth of these plates, and their ultimate consumption back into the Earth's deep interior through subduction zones provide an efficient mechanism to cool the earth's mantle, leading to large-scale mantle convection. Mantle plumes, which explain another set of global geological phenomena such as within-plate volcanism, cool the earth's deep interior (probably the Earth's core) and represent another mode of Earth's thermal convection. Plate tectonic theory and mantle plume hypothesis thus complement each other to explain much of the whole picture of Earth processes and phenomena.

  7. Comparison of the measured and modeled electron densities and temperatures in the ionosphere and plasmasphere during the period 25-29 June 1990

    Science.gov (United States)

    Pavlov, A. V.; Abe, T.; Oyama, K.-I.

    2001-04-01

    We present a comparison of the electron density and temperature behavior measured in the ionosphere by the Millstone Hill incoherent-scatter radar during the period 25-29 June 1990, and in the plasmasphere within the Millstone Hill magnetic field flux tube by the instruments on board of the EXOS-D satellite in the Northern Hemisphere between 02:07:56 UT and 02:11:08 UT on 28 June 1990 with numerical model calculations from a time-dependent mathematical model of the Earth's ionosphere and plasmasphere. We have evaluated the value of the nighttime additional heating rate that should be added to the normal photoelectron heating in the electron energy equation in the plasmasphere region above 5000 km along the magnetic field line to explain the high electron temperature measured by the instruments on board of the EXOS-D satellite. The additional heating brings the measured and modeled electron temperatures into agreement with the plasmasphere and into very large disagreement with the ionosphere if the classical electron heat flux along magnetic field line is used in the model. The approach of Pavlov et al. (Annales Geophysicae 18 (2000) 1257-1272) based on an effective electron thermal conductivity coefficient along the magnetic field line, is used to explain the measured electron temperature in the ionosphere and plasmasphere. This approach leads to a heat flux which is less than that given by the classical Spitzer-Harm theory. The evaluated additional heating of electrons in the plasmasphere and the decrease of the thermal conductivity in the topside ionosphere and the greater part of the plasmasphere allow the model to accurately reproduce the electron temperatures observed by the instruments on board of the EXOS-D satellite in the plasmasphere and the Millstone Hill incoherent-scatter radar in the ionosphere. The resulting effect of vibrationally excited N2 and O2 on NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 2. The modeled electron

  8. Akebono (EXOS-D) sounder data archive for studies of the ionosphere and plasmasphere

    Science.gov (United States)

    Kumamoto, A.; Katoh, Y.; Obara, T.

    2016-12-01

    For the purpose of topside sounding of the ionosphere and active experiments of the plasma waves in geospace, a sounder system was installed on the Akebono (EXOS-D) satellite, which was operated in a period from 1989 to 2015. Through the long operation period, the sounder system was also operated successfully, and brought us 117,468 ionograms in a frequency range from 0.02-0.89 MHz and 31,936 ionograms in a frequency range from 0.3-11.4 MHz taken within 2.6 Re. In order to provide the data to world-wide researchers' use, we are preparing data archive of Akebono Sounder data in Common Data Format (CDF) and Planetary Data System (PDS) format. Calibrated ionograms will be provided as Level-2 data. In addition, we are going to perform echo trace of the ionograms, and derive the vertical profile of the electron number density below the satellite. The horizontal and vertical distribution of the number density of the topside ionosphere along the satellite path will be provided as Level-3 data. However, because we need some efforts in manual echo tracing with numerous ionograms, it will take some time to finish the release of Level-3 data. So, we are going to prepare another simplified Leve-3 data, which provides the horizontal and apparent (assuming light-speed propagation) vertical distribution of the reflection point of the echo at some fixed frequency. The dataset will be enough useful in finding irregular plasma structures around auroral ionosphere and storm-time plasmasphere.

  9. AUTOSCALA software improvements: topside-plasmasphere profiles and TEC model assisted by AIS ionosonde measurements

    Science.gov (United States)

    Cesaroni, C.; Ippolito, A.; Scotto, C.; Ciraolo, L.

    2012-12-01

    The group of Upper Atmosphere Physics at INGV (Istituto Nazionale di Geofisica e Vulcanologia) developed Autoscala, a computer program for automatic scaling of the critical frequency foF2 and other ionospheric parameters derived from ionograms. Autoscala includes a routine that automatically estimates the electron density profile below F layer peak height hmF2, by adjusting the parameters of a model according to the recorded ionogram [Scotto (2009)]. Recently we have introduced a new algorithm for modeling upper ionosphere and plasmasphere electron density profiles following the approach suggested by Kutiev et al. (2009). In particular, these model uses the parameters of F layer peak (foF2, hmF2, scale height at hmF2) to obtain scale heights that are useful to construct H- and O+ density profiles, and consequently N(h) profile (given as the sum of the former two). Integrating electron density profiles we are then able to obtain a real time TEC estimation above the considered ionospheric station. A first validation of the model is carried out for data measured at Rome ionospheric station (Italy, 41°54' N 12°28' E) using independent TEC measurements from GPS receivers. References: Scotto, C. (2009). Electron density profile calculation technique for Autoscala ionogram analysis. Advances in Space Research, 44(6), 756-766. doi:10.1016/j.asr.2009.04.037 Kutiev, I., Marinov, P., Belehaki, a., Reinisch, B., & Jakowski, N. (2009). Reconstruction of topside density profile by using the topside sounder model profiler and digisonde data. Advances in Space Research, 43(11), 1683-1687. doi:10.1016/j.asr.2008.08.017

  10. He+ dominance in the plasmasphere during geomagnetically disturbed periods: 1. Observational results

    Directory of Open Access Journals (Sweden)

    C. R. Wilford

    Full Text Available Observations made by the DMSP F10 satellite during the recovery phase from geomagnetic disturbances in June 1991 show regions of He+ dominance around 830 km altitude at 09:00 MLT. These regions are co-located with a trough in ionisation observed around 55° in the winter hemisphere. Plasma temperature and concentration observations made during the severe geomagnetic storm of 24 March 1991 are used as a case study to determine the effects of geomagnetic disturbances along the orbit of the F10 satellite. Previous explanations for He+ dominance in this trough region relate to the part of the respective flux tubes that is in darkness. Such conditions are not relevant for this study, since the whole of the respective flux tubes are sunlit. A new mechanism is proposed to explain the He+ dominance in the trough region. This mechanism is based on plasma transport and chemical reaction effects in the F-region and topside ionosphere, and on the time scales for such chemical reactions. Flux tubes previously depleted by geomagnetic storm effects refill during the recovery phase from the ionosphere as a result of pressure differences along the flux tubes. Following a geomagnetic disturbance, the He+ ion recovers quickly via the rapid photoionisation of neutral helium, in the F-region and the topside. The recovery of the O+ and H+ ions is less rapid. This is proposed as a result of the respective charge exchange reactions with neutral atomic hydrogen and oxygen. Preliminary model calculations support the proposed mechanism.Key words. Magnetospheric physics (storms and sub-storms, plasmasphere

  11. Transverse eV ion heating by random electric field fluctuations in the plasmasphere

    Science.gov (United States)

    Artemyev, A. V.; Mourenas, D.; Agapitov, O. V.; Blum, L.

    2017-02-01

    Charged particle acceleration in the Earth inner magnetosphere is believed to be mainly due to the local resonant wave-particle interaction or particle transport processes. However, the Van Allen Probes have recently provided interesting evidence of a relatively slow transverse heating of eV ions at distances about 2-3 Earth radii during quiet times. Waves that are able to resonantly interact with such very cold ions are generally rare in this region of space, called the plasmasphere. Thus, non-resonant wave-particle interactions are expected to play an important role in the observed ion heating. We demonstrate that stochastic heating by random transverse electric field fluctuations of whistler (and possibly electromagnetic ion cyclotron) waves could explain this weak and slow transverse heating of H+ and O+ ions in the inner magnetosphere. The essential element of the proposed model of ion heating is the presence of trains of random whistler (hiss) wave packets, with significant amplitude modulations produced by strong wave damping, rapid wave growth, or a superposition of wave packets of different frequencies, phases, and amplitudes. Such characteristics correspond to measured characteristics of hiss waves in this region. Using test particle simulations with typical wave and plasma parameters, we demonstrate that the corresponding stochastic transverse ion heating reaches 0.07-0.2 eV/h for protons and 0.007-0.015 eV/h for O+ ions. This global temperature increase of the Maxwellian ion population from an initial Ti˜0.3 eV could potentially explain the observations.

  12. Transverse eV Ion Heating by Random Electric Field Fluctuations in the Plasmasphere

    Science.gov (United States)

    Artemyev, A. V.; Mourenas, D.; Agapitov, O. V.; Blum, L.

    2017-01-01

    Charged particle acceleration in the Earth inner magnetosphere is believed to be mainly due to the local resonant wave-particle interaction or particle transport processes. However, the Van Allen Probes have recently provided interesting evidence of a relatively slow transverse heating of eV ions at distances about 2-3 Earth radii during quiet times. Waves that are able to resonantly interact with such very cold ions are generally rare in this region of space, called the plasmasphere. Thus, non-resonant wave-particle interactions are expected to play an important role in the observed ion heating. We demonstrate that stochastic heating by random transverse electric field fluctuations of whistler (and possibly electromagnetic ion cyclotron) waves could explain this weak and slow transverse heating of H+ and O+ ions in the inner magnetosphere. The essential element of the proposed model of ion heating is the presence of trains of random whistler (hiss) wave packets, with significant amplitude modulations produced by strong wave damping, rapid wave growth, or a superposition of wave packets of different frequencies, phases, and amplitudes. Such characteristics correspond to measured characteristics of hiss waves in this region. Using test particle simulations with typical wave and plasma parameters, we demonstrate that the corresponding stochastic transverse ion heating reaches 0.07-0.2 eV/h for protons and 0.007-0.015 eV/h for O+ ions. This global temperature increase of the Maxwellian ion population from an initial Ti approx. 0.3 eV could potentially explain the observations.

  13. SAMI3 prediction of the impact of the 21 August 2017 total solar eclipse on the ionosphere/plasmasphere system

    Science.gov (United States)

    Huba, J. D.; Drob, D.

    2017-06-01

    We present quantitative predictions of the impact of the upcoming total solar eclipse on the ionosphere and plasmasphere using the Naval Research Laboratory (NRL) model Sami3 is Also a Model of the Ionosphere (SAMI3). The eclipse will occur over the continental United States on 21 August 2017. Our simulation results indicate that in the vicinity of the eclipse (1) the total electron content (TEC) decreases by up to ˜ 5 TEC units (TECU; 1 TECU = ×1016 m-2) which is a ˜ 35% decrease in TEC, (2) the electron density decreases by a factor of ˜ 50% in the F region, (3) the electron temperature decreases by up to ˜800 K in the plasmasphere, and (4) the O+ velocity changes from ˜40 m s-1 upward to ˜20 m s-1 downward in the F region. Interestingly, the continental size modification of the ionospheric conductance modifies the global electric field, which should lead to measurable changes in the TEC in the southern conjugate hemisphere (≲1 TECU).

  14. Relationship between plume and plate tectonics

    Science.gov (United States)

    Puchkov, V. N.

    2016-07-01

    The relationship between plate- and plume-tectonics is considered in view of the growth and breakdown of supercontinents, active rifting, the formation of passive volcanic-type continental margins, and the origin of time-progressive volcanic chains on oceanic and continental plates. The mantle wind phenomenon is described, as well as its effect on plume morphology and anisotropy of the ambient mantle. The interaction of plumes and mid-ocean ridges is discussed. The principles and problems of plume activity analysis in subduction- and collision-related foldbelts are considered and illustrated with examples.

  15. Redox conditions for mantle plumes

    Science.gov (United States)

    Heister, L. E.; Lesher, C. E.

    2005-12-01

    The vanadium to scandium ratio (V/Sc) for basalts from mid-ocean ridge (MOR) and arc environments has been proposed as a proxy for fO2 conditions during partial melting (e.g. [1] and [2]). Contrary to barometric measurements of the fO2 of primitive lavas, the V/Sc ratio of the upper mantle at mid-ocean ridges and arcs is similar, leading previous authors to propose that the upper mantle has uniform redox potential and is well-buffered. We have attempted to broaden the applicability of the V/Sc parameter to plume-influenced localities (both oceanic and continental), where mantle heterogeneities associated with recycled sediments, mafic crust, and metasomatized mantle, whether of shallow or deep origin, exist. We find that primitive basalts from the North Atlantic Igneous Province (NAIP), Hawaii (both the Loa and Kea trends), Deccan, Columbia River, and Siberian Traps show a range of V/Sc ratios that are generally higher (average ~9) than those for MOR (average ~ 6.7) or arc (average ~7) lavas. Based on forward polybaric decompression modeling, we attribute these differences to polybaric melting and melt segregation within the garnet stability field rather than the presence of a more oxidized mantle in plume-influenced settings. Like MORB, the V/Sc ratios for plume-influenced basalts can be accounted for by an oxidation state approximately one log unit below the Ni-NiO buffer (NNO-1). Our analysis suggests that source heterogeneities have little, if any, resolvable influence on mantle redox conditions, although they have significant influence on the trace element and isotopic composition of mantle-derived melts. We suggest that variations in the redox of erupted lavas is largely a function of shallow lithospheric processes rather than intrinsic to the mantle source, regardless of tectonic setting. [1] Li and Lee (2004) EPSL, [2] Lee et al. (2005) J. of Petrology

  16. Pulsed Plasma Thruster plume analysis

    Energy Technology Data Exchange (ETDEWEB)

    Parker, K. [Washington Univ., Aerospace and Energetics Research Program, Seattle, WA (United States)

    2003-11-01

    Micro-Pulsed Plasma Thrusters ({mu}PPTs) are a promising method for precision attitude control for small spacecraft in formation flying. They create an ionized plasma plume, which may interfere with other spacecraft in the formation. To characterize the ions in the plume, a diagnostic has been built that couples a drift tube with an energy analyzer. The drift tube provides time of flight measurements to determine the exhaust velocity, and the energy analyzer discriminates the ion energies. The energy analyzer measures the current on a collector plate downstream of four grids that repel electrons and ions below a specified energy. The first grid lowers the density of the plasma, therefore increasing Debye length. The second and fourth grids have a negative potential applied to them so they repel the electrons, while the third grid's voltage can be varied to repel lower energy ions. The ion energies can be computed by differentiating the data. Combining the information of the ion energies and their velocities identifies the ion masses in the PPT plume. The PPT used for this diagnostic is the micro-PPT developed for the Dawgstar satellite. This PPT uses 5.2 Joules per pulse and has a 2.3 cm{sup 2} propellant area, a 1.3 cm electrode length, and an estimated thrust of 85 {mu}N [C. Rayburn et al., AIAA-2000-3256]. This paper will describe the development and design of the time of flight/gridded energy analyzer diagnostic and present recent experimental results. (Author)

  17. Plume spread and atmospheric stability

    Energy Technology Data Exchange (ETDEWEB)

    Weber, R.O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The horizontal spread of a plume in atmospheric dispersion can be described by the standard deviation of horizontal direction. The widely used Pasquill-Gifford classes of atmospheric stability have assigned typical values of the standard deviation of horizontal wind direction and of the lapse rate. A measured lapse rate can thus be used to estimate the standard deviation of wind direction. It is examined by means of a large dataset of fast wind measurements how good these estimates are. (author) 1 fig., 2 refs.

  18. Characteristics of bubble plumes, bubble-plume bubbles and waves from wind-steepened wave breaking

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G. de

    2007-01-01

    Observations of breaking waves, associated bubble plumes and bubble-plume size distributions were used to explore the coupled evolution of wave-breaking, wave properties and bubble-plume characteristics. Experiments were made in a large, freshwater, wind-wave channel with mechanical wind-steepened w

  19. Detection and tracking of gas plumes in LWIR hyperspectral video sequence data

    Science.gov (United States)

    Gerhart, Torin; Sunu, Justin; Lieu, Lauren; Merkurjev, Ekaterina; Chang, Jen-Mei; Gilles, Jérôme; Bertozzi, Andrea L.

    2013-05-01

    Automated detection of chemical plumes presents a segmentation challenge. The segmentation problem for gas plumes is difficult due to the diffusive nature of the cloud. The advantage of considering hyperspectral images in the gas plume detection problem over the conventional RGB imagery is the presence of non-visual data, allowing for a richer representation of information. In this paper we present an effective method of visualizing hyperspectral video sequences containing chemical plumes and investigate the effectiveness of segmentation techniques on these post-processed videos. Our approach uses a combination of dimension reduction and histogram equalization to prepare the hyperspectral videos for segmentation. First, Principal Components Analysis (PCA) is used to reduce the dimension of the entire video sequence. This is done by projecting each pixel onto the first few Principal Components resulting in a type of spectral filter. Next, a Midway method for histogram equalization is used. These methods redistribute the intensity values in order to reduce icker between frames. This properly prepares these high-dimensional video sequences for more traditional segmentation techniques. We compare the ability of various clustering techniques to properly segment the chemical plume. These include K-means, spectral clustering, and the Ginzburg-Landau functional.

  20. Radiation Chemistry of Potential Europa Plumes

    Science.gov (United States)

    Gudipati, M. S.; Henderson, B. L.

    2014-12-01

    Recent detection of atomic hydrogen and atomic oxygen and their correlation to potential water plumes on Europa [Roth, Saur et al. 2014] invoked significant interest in further understanding of these potential/putative plumes on Europa. Unlike on Enceladus, Europa receives significant amount of electron and particle radiation. If the plumes come from trailing hemisphere and in the high radiation flux regions, then it is expected that the plume molecules be subjected to radiation processing. Our interest is to understand to what extent such radiation alterations occur and how they can be correlated to the plume original composition, whether organic or inorganic in nature. We will present laboratory studies [Henderson and Gudipati 2014] involving pulsed infrared laser ablation of ice that generates plumes similar to those observed on Enceladus [Hansen, Esposito et al. 2006; Hansen, Shemansky et al. 2011] and expected to be similar on Europa as a starting point; demonstrating the applicability of laser ablation to simulate plumes of Europa and Enceladus. We will present results from electron irradiation of these plumes to determine how organic and inorganic composition is altered due to radiation. Acknowledgments:This research was enabled through partial funding from NASA funding through Planetary Atmospheres, and the Europa Clipper Pre-Project. B.L.H. acknowledges funding from the NASA Postdoctoral Program for an NPP fellowship. Hansen, C. J., L. Esposito, et al. (2006). "Enceladus' water vapor plume." Science 311(5766): 1422-1425. Hansen, C. J., D. E. Shemansky, et al. (2011). "The composition and structure of the Enceladus plume." Geophysical Research Letters 38. Henderson, B. L. and M. S. Gudipati (2014). "Plume Composition and Evolution in Multicomponent Ices Using Resonant Two-Step Laser Ablation and Ionization Mass Spectrometry." The Journal of Physical Chemistry A 118(29): 5454-5463. Roth, L., J. Saur, et al. (2014). "Transient Water Vapor at Europa's South

  1. Variability and Composition of Io's Pele Plume

    Science.gov (United States)

    Jessup, K. L.; Spencer, J.; Yelle, R.

    2004-11-01

    The Pele plume is one of the largest and most dynamic of the plumes on Io. While sulfur dioxide (SO2) gas was always assumed to be a constituent of this plume, spectral observations obtained in 1999 were the first to positively identify elemental sulfur (S2) (Spencer et al. 2000) within the Pele plume. The S2/SO2 ratio derived from this observation provided a critical component necessary for the constraint of the magma chemistry and vent conditions of the Pele plume (Zolotov and Fegley 1998). But, because the Pele plume has long been known to be variable in its eruptive behavior, it is not likely that the vent conditions are invariant. Consequently, additional observations were needed to constrain the extent of the variability of the plume's composition and gas abundances. To this end, in February 2003, March 2003 and January 2004 we obtained spectra of Pele with Hubble's Space Telescope Imaging Spectrograph (STIS) in transit of Jupiter, using the 0.1 arcsec slit, for the wavelength region extending from 2100-3100 Å. Contemporaneous with the spectral data we also obtained UV and visible-wavelength images of the plume in reflected sunlight with the Advanced Camera for Surveys (ACS) prior to Jupiter transit, in order to constrain plume dust abundance. The newly acquired STIS data show both the S2 and SO2 absorption signatures, and provide concrete evidence of temporal variability in the abundance of these gases. Likewise, the degree of dust scattering recorded in the ACS data varied as a function of the date of observation. We will present preliminary constraints on the composition and variability of the gas abundances of the Pele plume as recorded within the STIS data. We will also give a brief overview of the variability of the plume dust signatures relative to the gas signatures as a function of time.

  2. Skylon Aerodynamics and SABRE Plumes

    Science.gov (United States)

    Mehta, Unmeel; Afosmis, Michael; Bowles, Jeffrey; Pandya, Shishir

    2015-01-01

    An independent partial assessment is provided of the technical viability of the Skylon aerospace plane concept, developed by Reaction Engines Limited (REL). The objectives are to verify REL's engineering estimates of airframe aerodynamics during powered flight and to assess the impact of Synergetic Air-Breathing Rocket Engine (SABRE) plumes on the aft fuselage. Pressure lift and drag coefficients derived from simulations conducted with Euler equations for unpowered flight compare very well with those REL computed with engineering methods. The REL coefficients for powered flight are increasingly less acceptable as the freestream Mach number is increased beyond 8.5, because the engineering estimates did not account for the increasing favorable (in terms of drag and lift coefficients) effect of underexpanded rocket engine plumes on the aft fuselage. At Mach numbers greater than 8.5, the thermal environment around the aft fuselage is a known unknown-a potential design and/or performance risk issue. The adverse effects of shock waves on the aft fuselage and plumeinduced flow separation are other potential risks. The development of an operational reusable launcher from the Skylon concept necessitates the judicious use of a combination of engineering methods, advanced methods based on required physics or analytical fidelity, test data, and independent assessments.

  3. Proceedings of plumes, plates and mineralisation symposium: an introduction

    CSIR Research Space (South Africa)

    Hatton, CJ

    1997-12-01

    Full Text Available of plume-theory. Mechanisms of magma formation are identified and plume positions and distances to their surface expression considered. Mantle plumes are considered as a heat and fluid source for the Witwatersrand gold deposits....

  4. Numerical modeling of mantle plume diffusion

    Science.gov (United States)

    Krupsky, D.; Ismail-Zadeh, A.

    2004-12-01

    To clarify the influence of the heat diffusion on the mantle plume evolution, we develop a two-dimensional numerical model of the plume diffusion and relevant efficient numerical algorithm and code to compute the model. The numerical approach is based on the finite-difference method and modified splitting algorithm. We consider both von Neumann and Direchlet conditions at the model boundaries. The thermal diffusivity depends on pressure in the model. Our results show that the plume is disappearing from the bottom up - the plume tail at first and its head later - because of the mantle plume geometry (a thin tail and wide head) and higher heat conductivity in the lower mantle. We study also an effect of a lateral mantle flow associated with the plate motion on the distortion of the diffusing mantle plume. A number of mantle plumes recently identified by seismic tomography seem to disappear in the mid-mantle. We explain this disappearance as the effect of heat diffusion on the evolution of mantle plume.

  5. Aggregate Particles in the Plumes of Enceladus

    CERN Document Server

    Gao, Peter; Zhang, Xi; Ingersoll, Andrew P

    2015-01-01

    Estimates of the total particulate mass of the plumes of Enceladus are important to constrain theories of particle formation and transport at the surface and interior of the satellite. We revisit the calculations of Ingersoll and Ewald (2011), who estimated the particulate mass of the Enceladus plumes from strongly forward scattered light in Cassini ISS images. We model the plume as a combination of spherical particles and irregular aggregates resulting from the coagulation of spherical monomers, the latter of which allows for plumes of lower particulate mass. Though a continuum of solutions are permitted by the model, the best fits to the ISS data consist either of low mass plumes composed entirely of small aggregates or high mass plumes composed of large aggregates and spheres. The high mass plumes can be divided into a population of large aggregates with total particulate mass of 116 +/- 12 X 10^3 kg, and a mixed population of spheres and aggregates consisting of a few large monomers that has a total plume...

  6. Infrared Sensing of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Petersen, Ole; Larsen, Torben

    1988-01-01

    This paper is concerned with laboratory experiments on buoyant surface plumes where heat is the source of buoyancy. Temperature distributions were measured at the water surface using infra-red sensing, and inside the waterbody a computer based measurement system was applied. The plume is described...

  7. Modelling oil plumes from subsurface spills.

    Science.gov (United States)

    Lardner, Robin; Zodiatis, George

    2017-07-11

    An oil plume model to simulate the behavior of oil from spills located at any given depth below the sea surface is presented, following major modifications to a plume model developed earlier by Malačič (2001) and drawing on ideas in a paper by Yapa and Zheng (1997). The paper presents improvements in those models and numerical testing of the various parameters in the plume model. The plume model described in this paper is one of the numerous modules of the well-established MEDSLIK oil spill model. The deep blowout scenario of the MEDEXPOL 2013 oil spill modelling exercise, organized by REMPEC, has been applied using the improved oil plume module of the MEDSLIK model and inter-comparison with results having the oil spill source at the sea surface are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Galileo observations of volcanic plumes on Io

    Science.gov (United States)

    Geissler, P.E.; McMillan, M.T.

    2008-01-01

    Io's volcanic plumes erupt in a dazzling variety of sizes, shapes, colors and opacities. In general, the plumes fall into two classes, representing distinct source gas temperatures. Most of the Galileo imaging observations were of the smaller, more numerous Prometheus-type plumes that are produced when hot flows of silicate lava impinge on volatile surface ices of SO2. Few detections were made of the giant, Pele-type plumes that vent high temperature, sulfur-rich gases from the interior of Io; this was partly because of the insensitivity of Galileo's camera to ultraviolet wavelengths. Both gas and dust spout from plumes of each class. Favorably located gas plumes were detected during eclipse, when Io was in Jupiter's shadow. Dense dust columns were imaged in daylight above several Prometheus-type eruptions, reaching heights typically less than 100 km. Comparisons between eclipse observations, sunlit images, and the record of surface changes show that these optically thick dust columns are much smaller in stature than the corresponding gas plumes but are adequate to produce the observed surface deposits. Mie scattering calculations suggest that these conspicuous dust plumes are made up of coarse grained “ash” particles with radii on the order of 100 nm, and total masses on the order of 106 kg per plume. Long exposure images of Thor in sunlight show a faint outer envelope apparently populated by particles small enough to be carried along with the gas flow, perhaps formed by condensation of sulfurous “snowflakes” as suggested by the plasma instrumentation aboard Galileo as it flew through Thor's plume [Frank, L.A., Paterson, W.R., 2002. J. Geophys. Res. (Space Phys.) 107, doi:10.1029/2002JA009240. 31-1]. If so, the total mass of these fine, nearly invisible particles may be comparable to the mass of the gas, and could account for much of Io's rapid resurfacing.

  9. Comparison of the measured and modelled electron densities and temperatures in the ionosphere and plasmasphere during 20-30 January, 1993

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    Full Text Available We present a comparison of the electron density and temperature behaviour in the ionosphere and plasmasphere measured by the Millstone Hill incoherent-scatter radar and the instruments on board of the EXOS-D satellite with numerical model calculations from a time-dependent mathematical model of the Earth's ionosphere and plasmasphere during the geomagnetically quiet and storm period on 20–30 January, 1993. We have evaluated the value of the additional heating rate that should be added to the normal photoelectron heating in the electron energy equation in the daytime plasmasphere region above 5000 km along the magnetic field line to explain the high electron temperature measured by the instruments on board of the EXOS-D satellite within the Millstone Hill magnetic field flux tube in the Northern Hemisphere. The additional heating brings the measured and modelled electron temperatures into agreement in the plasmasphere and into very large disagreement in the ionosphere if the classical electron heat flux along magnetic field line is used in the model. A new approach, based on a new effective electron thermal conductivity coefficient along the magnetic field line, is presented to model the electron temperature in the ionosphere and plasmasphere. This new approach leads to a heat flux which is less than that given by the classical Spitzer-Harm theory. The evaluated additional heating of electrons in the plasmasphere and the decrease of the thermal conductivity in the topside ionosphere and the greater part of the plasmasphere found for the first time here allow the model to accurately reproduce the electron temperatures observed by the instruments on board the EXOS-D satellite in the plasmasphere and the Millstone Hill incoherent-scatter radar in the ionosphere. The effects of the daytime additional plasmaspheric heating of electrons on the electron temperature and density are small at the F-region altitudes if the modified electron heat flux

  10. Enhancements of magnetospheric convection electric field associated with sudden commencements in the inner magnetosphere and plasmasphere regions

    Science.gov (United States)

    Shinbori, A.; Ono, T.; Iizima, M.; Kumamoto, A.; Nishimura, Y.

    2006-01-01

    Electric field variations in the inner magnetosphere and plasmasphere regions associated with sudden commencements (SCs) are investigated by using the observation data of the Akebono satellite which has been carried out more than 15 years since 1989. 117 of 153 SC events in the low-latitude (MLAT bi-polar waveform due to the passage of fast-mode hydromagnetic (HM) waves. The increase of the convection electric field takes place in the entire magnetic local time sector in the inner magnetosphere. The amplitude does not depend on L-value and magnetic local time but is proportional to the SC amplitude measured at Kakioka. The majority of the electric field enhancements persist for about 4 14 min. The origin of the convection electric field in the inner magnetosphere is a plasma motion caused by the compression of the magnetosphere due to the solar wind shock and discontinuity.

  11. ISEE 1 observations of thermal plasma in the vicinity of the plasmasphere during periods of quieting magnetic activity

    Science.gov (United States)

    Horwitz, J. L.; Baugher, C. R.; Chappell, C. R.; Shelley, E. G.; Young, D. T.; Anderson, R. R.

    1981-11-01

    An investigation of thermal plasma behavior in the vicinity of the plasmasphere during periods of quieting magnetic activity was conducted by combining thermal ion observations made with the plasma composition experiment on ISEE 1 with plasma density profiles obtained from plasma frequency measurements made with the same satellite's plasma wave experiment. During periods in which the magnetic activity quiets, the two regions characterized by H(+):He(+):O(+) (isotropic) and H(+):O(+):He(+) (field-aligned) ion species distributions (in order of dominance) are separated by a new region in which low-energy H(+) and He(+) are found flowing along the magnetic field lines. At other times, following quieting magnetic activity, distributions having peak fluxes at 90 deg pitch angle are observed in this region.

  12. Intra-plasmaspheric wave power density deduced from long-term DEMETER measurements of terrestrial VLF transmitter wave amplitudes

    Science.gov (United States)

    Lauben, D.; Cohen, M.; Inan, U.

    2012-12-01

    We deduce the 3d intra-plasmaspheric distribution of VLF wave power between conjugate regions of strong VLF wave amplitudes as measured by DEMETER for high-power terrestrial VLF transmitters during its ~6-yr lifetime. We employ a mixed WKB/full-wave technique to solve for the primary and secondary electromagnetic and electrostatic waves which are transmitted and reflected from strong cold-plasma density gradients and posited irregularities, in order to match the respective end-point measured amplitude distributions. Energy arriving in the conjugate region and also escaping to other regions of the magnetosphere is note. The resulting 3d distribution allows improved estimates for the long-term average particle scattering induced by terrestrial VLF transmitters.

  13. Digital filtering of plume emission spectra

    Science.gov (United States)

    Madzsar, George C.

    1990-01-01

    Fourier transformation and digital filtering techniques were used to separate the superpositioned spectral phenomena observed in the exhaust plumes of liquid propellant rocket engines. Space shuttle main engine (SSME) spectral data were used to show that extraction of spectral lines in the spatial frequency domain does not introduce error, and extraction of the background continuum introduces only minimal error. Error introduced during band extraction could not be quantified due to poor spectrometer resolution. Based on the atomic and molecular species found in the SSME plume, it was determined that spectrometer resolution must be 0.03 nm for SSME plume spectral monitoring.

  14. Merging Thermal Plumes in the Indoor Environment

    DEFF Research Database (Denmark)

    Bjørn, Erik; Nielsen, Peter V.

    This experimental work deals with the basic problem of merging thermal plumes from heat sources situated in the vicinity of each other. No studies have been made yet of how close two heat sources must be to each other, before they can be considered as a single source with a cumulative heat effect......, and how far apart they must be to be considered separate. Also, it is not known how the flow field behaves in the intermediate fase, where the plumes are neither completely joined nor completely separate. A possible, very simple, solution of the velocity distribution between two plumes is to assume...

  15. Etude de la magnétosphère terrestre par l'analyse multipoint des données de la mission CLUSTER. Contributions à la caractérisation des frontières et de la magnétosphère interne

    OpenAIRE

    Darrouzet, Fabien

    2006-01-01

    CLUSTER is the first space mission dedicated to the three-dimensional study of the terrestrial magnetosphere. Its polar orbit and four spacecraft tetrahedron formation allow it to make in situ measurements in various regions of the magnetosphere, in particular in the plasmasphere. This PhD thesis brings together several studies on plasma structures encountered by the CLUSTER spacecraft along their orbit, during the time period 2001-2004. The physical quantity analysed here is mainly the elect...

  16. Characterizing a sewage plume using the 3H-3He dating technique

    Science.gov (United States)

    Shapiro, Stephanie Dunkle; LeBlanc, Denis; Schlosser, Peter; Ludin, Andrea

    1999-01-01

    An extensive 3H-3He study was performed to determine detailed characteristics of a regional flow system and a sewage plume over a distance of 4 km in a sand and gravel aquifer at Otis Air Base in Falmouth, Massachusetts. 3H-3He ages increase with depth in individual piezometer clusters and with distance along flowpaths. However, the age gradient with depth (Δt/Δz) is smaller in the plume than that in the regional waters, due to the intense recharge in the infiltration beds. The 1960s bomb peak of tritium in precipitation is archived longitudinally along a flowline through the main axis of the plume and vertically in individual piezometer clusters. On the eastern side of the sampling area, where water from Ashumet Pond forces plume water deeper into the flow system, 3H-3He ages are young at depth because the 3H-3He "clock" is reset due to outgassing of helium in the pond. A reconstruction of the tritium input functions for the regional and plume samples shows that there is no offset in the peak [3H]+[3Hetrit] concentrations for the plume and regional water, indicating that the water from supply wells for use on the base is young. The 3H-3He ages and detergent concentrations in individual wells are consistent with the beginning of use of detergents and the time period when their concentrations in sewage would have been greatest. Ages and hydraulic properties calculated using the 3H-3He data compare well with those from previous investigations and from particle-tracking simulations.

  17. Passive acoustic records of two vigorous bubble-plume methane seeps on the Oregon continental margin

    Science.gov (United States)

    Dziak, R. P.; Matsumoto, H.; Merle, S. G.; Embley, R. W.; Baumberger, T.; Hammond, S. R.

    2016-12-01

    We present preliminary analysis of the acoustic records of two bubble-plume methane seeps recorded by an autonomous hydrophone deployed during the E/V Nautilus expedition (NA072) in June 2016. The goal of the NA072 expedition was to use the Simrad 302 as a survey tool to map bubble plumes at a regional scale along the Oregon and northern California margins, followed by in situ investigation of bubble-plume sites using the ROV Hercules. The exploration carried out during NA072 resulted in the discovery of hundreds of new individual methane seep sites in water depths ranging from 125 to 1725 m depth. A Greenridge Acousonde 3B™ hydrophone was deployed via ROV within two vigorous bubble-plume sites. Despite persistent ship and ROV propeller noise, the acoustic signature of the bubble-plume can be seen in the hydrophone record as a broadband (0.5 - 4.5 kHz) series of short duration ( 0.2-0.5 msec) pulses that occur in clusters of dozens of pulses lasting 2-3 secs. Previous studies of the passive acoustics of seep bubble-plumes indicate sound is generated during bubble formation, where detachment of the gas bubble from the end of a tube or conduit causes the bubble to oscillate, producing sound. The peak frequency f (the zeroth oscillatory mode) and the bubble equivalent spherical radius r for a given pressure P are: f = (2πr)-1 [(3γP/ρ)]1/2 where γ is the ratio of gas specific heat at constant pressure to constant volume and ρ is the water density (Leifer and Tang, 2006). Thus the frequency of a bubble's oscillation is proportional to the bubble's volume, and therefore it may be possible to use our acoustic data to obtain an estimate of the volume of methane being released at these seafloor plume sites.

  18. Ions in the Enceladus plume: Cassini/CAPS ion measurements at high energy resolution

    Science.gov (United States)

    Crary, F.; Coates, A. J.; Hill, T. W.; Jones, G. H.; Tokar, R. L.

    2012-12-01

    During several Cassini encounters with Saturn's satellite, Enceladus, the spacecraft crossed through the plume of water vapor and dust south of the satellite with a spacecraft orientation which allowed the Cassini Plasma Spectrometer (CAPS) to observe ions and nanograin dust particles associated with the plume. During three of these encounters, E7 (November 2, 2009), E17 (March XX, 2012) and E18 (April YY, 2012), the trajectories were very similar and parallel to the equatorial plane (i.e. little north-south velocity, so that the spacecraft moved perpendicular to the rotation axis of Enceladus.) Previous analysis, using data from the CAPS ion mass spectrometer (IMS) and electron spectrometer (ELS), identified cold ions at rest with respect to Enceladus [1], negative water group and water cluster ions [2], and both positively and negatively charged dust particles in the 0.5 to 2 nm (1000 to 20,000 AMU) size range [3,4]. We present observations from the third CAPS sensor, the ion beam spectrometer (IBS). Although this sensor lacks the angular resolution of the other CAPS sensors, it has an energy resolution of 1.4%, roughly an order of magnitude greater than the ELS and IMS sensors. The IBS data allows us to estimate the temperature and flow speed of the low energy ions in the plume, and characterize the structure of the plume ionosphere. We find that the plume is highly structured, down to the 2-s (17 km along track) limit of the instrument's sampling. Distinct regions of cold, dense ions, resembling a collisional ionosphere, are intermixed with a broad background of warmer, non-thermal ions, possibly resulting from charge exchange between magnetospheric ions and plume neutrals. Despite the sensor's lack of intrinsic angular resolution, the ion flux and energy spectra are consistent with a drift velocity away from Saturn and in the direction of the upstream flow. References: [1] Tokar et al., 2009, Cassini detection of Enceladus' cold water-group plume ionosphere

  19. Assessment of analytical techniques for predicting solid propellant exhaust plumes and plume impingement environments

    Science.gov (United States)

    Tevepaugh, J. A.; Smith, S. D.; Penny, M. M.

    1977-01-01

    An analysis of experimental nozzle, exhaust plume, and exhaust plume impingement data is presented. The data were obtained for subscale solid propellant motors with propellant Al loadings of 2, 10 and 15% exhausting to simulated altitudes of 50,000, 100,000 and 112,000 ft. Analytical predictions were made using a fully coupled two-phase method of characteristics numerical solution and a technique for defining thermal and pressure environments experienced by bodies immersed in two-phase exhaust plumes.

  20. Sensitivity of air quality simulation to smoke plume rise

    Science.gov (United States)

    Yongqiang Liu; Gary Achtemeier; Scott Goodrick

    2008-01-01

    Plume rise is the height smoke plumes can reach. This information is needed by air quality models such as the Community Multiscale Air Quality (CMAQ) model to simulate physical and chemical processes of point-source fire emissions. This study seeks to understand the importance of plume rise to CMAQ air quality simulation of prescribed burning to plume rise. CMAQ...

  1. Heard Island and McDonald Islands Acoustic Plumes: Split-beam Echo sounder and Deep Tow Camera Observations of Gas Seeps on the Central Kerguelen Plateau

    Science.gov (United States)

    Watson, S. J.; Spain, E. A.; Coffin, M. F.; Whittaker, J. M.; Fox, J. M.; Bowie, A. R.

    2016-12-01

    Heard and McDonald islands (HIMI) are two active volcanic edifices on the Central Kerguelen Plateau. Scientists aboard the Heard Earth-Ocean-Biosphere Interactions voyage in early 2016 explored how this volcanic activity manifests itself near HIMI. Using Simrad EK60 split-beam echo sounder and deep tow camera data from RV Investigator, we recorded the distribution of seafloor emissions, providing the first direct evidence of seabed discharge around HIMI, mapping >244 acoustic plume signals. Northeast of Heard, three distinct plume clusters are associated with bubbles (towed camera) and the largest directly overlies a sub-seafloor opaque zone (sub-bottom profiler) with >140 zones observed within 6.5 km. Large temperature anomalies did not characterize any of the acoustic plumes where temperature data were recorded. We therefore suggest that these plumes are cold methane seeps. Acoustic properties - mean volume backscattering and target strength - and morphology - height, width, depth to surface - of plumes around McDonald resembled those northeast of Heard, also suggesting gas bubbles. We observed no bubbles on extremely limited towed camera data around McDonald; however, visibility was poor. The acoustic response of the plumes at different frequencies (120 kHz vs. 18 kHz), a technique used to classify water column scatterers, differed between HIMI, suggestiing dissimilar target size (bubble radii) distributions. Environmental context and temporal characteristics of the plumes differed between HIMI. Heard plumes were concentrated on flat, sediment rich plains, whereas around McDonald plumes emanated from sea knolls and mounds with hard volcanic seafloor. The Heard plumes were consistent temporally, while the McDonald plumes varied temporally possibly related to tides or subsurface processes. Our data and analyses suggest that HIMI acoustic plumes were likely caused by gas bubbles; however, the bubbles may originate from two or more distinct processes.

  2. Characteristics of the Great Whale River plume

    Science.gov (United States)

    Ingram, R. Grant

    1981-03-01

    Observations of the motion field and dilution effects associated with the plume of Great Whale River in Hudson Bay are presented for both open water and ice-covered conditions. In the summer months a distinct plume of about 100 km2 in area is formed offshore which is characterized by a 1-2 m thickness and large velocities directed away from the river mouth in contrast to slower currents parallel to the shore in the ambient waters underneath. Surface drifter results suggest that the outer boundary of plume may be a zone of frontal convergence. Under ice-covered conditions the plume was significantly thicker and extended much farther offshore in spite of a marked reduction in river runoff at this time.

  3. Mantle plumes: Why the current skepticism?

    Institute of Scientific and Technical Information of China (English)

    Gillian R. Foulger

    2005-01-01

    The present reappraisal of the mantle plume hypothesis is perhaps the most exciting current debate in Earth science. Nevertheless, the fundamental reasons for why it has arisen are often not well understood. They are that 1) many observations do not agree with the predictions of the original model, 2) it is possible that convection of the sort required to generate thermal plumes in the Earth's mantle does not occur, 3) so many variants of the original model have been invoked to accommodate conflicting data that the plume hypthesis is in practice no longer testable, and 4) alternative models are viable, though these have been largely neglected by researchers. Regardless of the final outcome, the present vigorous debate is to be welcomed since it is likely to stimulate new discoveries in a way that unquestioning acceptance of the conventional plume model will not.

  4. Plume Diagnostics for Combustion Stability Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Sierra Engineering Inc. and Purdue University propose to develop a non-intrusive plume instrument capable of detecting and diagnosing combustion instability. This...

  5. Hydroxyl Tagging Velocimetry for Rocket Plumes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the need for non-intrusive sensors for rocket plume properties, we propose a laser-based velocity diagnostic that does not require seeding, works in high...

  6. Novel plume deflection concept testing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort will explore the feasibility and effectiveness of utilizing an electrically driven thermal shield for use as part of rocket plume deflectors. To...

  7. Plume Ascent Tracker: Interactive Matlab software for analysis of ascending plumes in image data

    Science.gov (United States)

    Valade, S. A.; Harris, A. J. L.; Cerminara, M.

    2014-05-01

    This paper presents Matlab-based software designed to track and analyze an ascending plume as it rises above its source, in image data. It reads data recorded in various formats (video files, image files, or web-camera image streams), and at various wavelengths (infrared, visible, or ultra-violet). Using a set of filters which can be set interactively, the plume is first isolated from its background. A user-friendly interface then allows tracking of plume ascent and various parameters that characterize plume evolution during emission and ascent. These include records of plume height, velocity, acceleration, shape, volume, ash (fine-particle) loading, spreading rate, entrainment coefficient and inclination angle, as well as axial and radial profiles for radius and temperature (if data are radiometric). Image transformations (dilatation, rotation, resampling) can be performed to create new images with a vent-centered metric coordinate system. Applications may interest both plume observers (monitoring agencies) and modelers. For the first group, the software is capable of providing quantitative assessments of plume characteristics from image data, for post-event analysis or in near real-time analysis. For the second group, extracted data can serve as benchmarks for plume ascent models, and as inputs for cloud dispersal models. We here describe the software's tracking methodology and main graphical interfaces, using thermal infrared image data of an ascending volcanic ash plume at Santiaguito volcano.

  8. Fire analog: a comparison between fire plumes and energy center cooling tower plumes

    Energy Technology Data Exchange (ETDEWEB)

    Orgill, M.M.

    1977-10-01

    Thermal plumes or convection columns associated with large fires are compared to thermal plumes from cooling towers and proposed energy centers to evaluate the fire analog concept. Energy release rates of mass fires are generally larger than for single or small groups of cooling towers but are comparable to proposed large energy centers. However, significant physical differences exist between cooling tower plumes and fire plumes. Cooling tower plumes are generally dominated by ambient wind, stability and turbulence conditions. Fire plumes, depending on burning rates and other factors, can transform into convective columns which may cause the fire behavior to become more violent. This transformation can cause strong inflow winds and updrafts, turbulence and concentrated vortices. Intense convective columns may interact with ambient winds to create significant downwind effects such as wakes and Karman vortex streets. These characteristics have not been observed with cooling tower plumes to date. The differences in physical characteristics between cooling tower and fire plumes makes the fire analog concept very questionable even though the approximate energy requirements appear to be satisfied in case of large energy centers. Additional research is suggested in studying the upper-level plume characteristics of small experimental fires so this information can be correlated with similar data from cooling towers. Numerical simulation of fires and proposed multiple cooling tower systems could also provide comparative data.

  9. Near-glacier surveying of a subglacial discharge plume: Implications for plume parameterizations

    Science.gov (United States)

    Jackson, R. H.; Shroyer, E. L.; Nash, J. D.; Sutherland, D. A.; Carroll, D.; Fried, M. J.; Catania, G. A.; Bartholomaus, T. C.; Stearns, L. A.

    2017-07-01

    At tidewater glaciers, plume dynamics affect submarine melting, fjord circulation, and the mixing of meltwater. Models often rely on buoyant plume theory to parameterize plumes and submarine melting; however, these parameterizations are largely untested due to a dearth of near-glacier measurements. Here we present a high-resolution ocean survey by ship and remotely operated boat near the terminus of Kangerlussuup Sermia in west Greenland. These novel observations reveal the 3-D structure and transport of a near-surface plume, originating at a large undercut conduit in the glacier terminus, that is inconsistent with axisymmetric plume theory, the most common representation of plumes in ocean-glacier models. Instead, the observations suggest a wider upwelling plume—a "truncated" line plume of ˜200 m width—with higher entrainment and plume-driven melt compared to the typical axisymmetric representation. Our results highlight the importance of a subglacial outlet's geometry in controlling plume dynamics, with implications for parameterizing the exchange flow and submarine melt in glacial fjord models.

  10. STRATAFORM Plume Study: Analysis and Modeling

    Science.gov (United States)

    1999-09-30

    of settling is explained by the variation of plume speed, rather than by variations in settling velocity (Hill et al., submitted). Floculation is an...mouth. However, the fraction of floculated sediment does not vary as much as expected with changes in forcing conditions. There do appear to be large...differences in the floculation rate between the extreme flood conditions of 1997 and the more moderate floods of 1998. The detailed examination of plume

  11. Rocket plume tomography of combustion species

    OpenAIRE

    2001-01-01

    Interest in accurate detection and targeting of aggressor missiles has received considerable interest with the national priority of developing a missile defense system. Understanding the thermal signatures of the exhaust plumes of such missiles is key to accomplishing that mission. Before signature models can be precisely developed for specific rockets, the radiation of the molecular or combustion species within those plumes must be accurately predicted. A combination translation / rotation s...

  12. OPAD data analysis. [Optical Plumes Anomaly Detection

    Science.gov (United States)

    Buntine, Wray L.; Kraft, Richard; Whitaker, Kevin; Cooper, Anita E.; Powers, W. T.; Wallace, Tim L.

    1993-01-01

    Data obtained in the framework of an Optical Plume Anomaly Detection (OPAD) program intended to create a rocket engine health monitor based on spectrometric detections of anomalous atomic and molecular species in the exhaust plume are analyzed. The major results include techniques for handling data noise, methods for registration of spectra to wavelength, and a simple automatic process for estimating the metallic component of a spectrum.

  13. Cretaceous Arctic magmatism: Slab vs. plume? Or slab and plume?

    Science.gov (United States)

    Gottlieb, E. S.; Miller, E. L.; Andronikov, A. V.; Brumley, K.; Mayer, L. A.; Mukasa, S. B.

    2010-12-01

    Tectonic models for the Cretaceous paleogeographic evolution of the Arctic Ocean and its adjacent landmasses propose that rifting in the Amerasia Basin (AB) began in Jura-Cretaceous time, accompanied by the development of the High Arctic Large Igneous Province (HALIP). During the same timespan, deformation and slab-related magmatism, followed by intra-arc rifting, took place along the Pacific side of what was to become the Arctic Ocean. A compilation and comparison of the ages, characteristics and space-time variation of circum-Arctic magmatism allows for a better understanding of the role of Pacific margin versus Arctic-Atlantic plate tectonics and the role of plume-related magmatism in the origin of the Arctic Ocean. In Jura-Cretaceous time, an arc built upon older terranes overthrust the Arctic continental margins of North America and Eurasia, shedding debris into foreland basins in the Brooks Range, Alaska, across Chukotka, Russia, to the Lena Delta and New Siberian Islands region of the Russian Arctic. These syn-tectonic sediments have some common sources (e.g., ~250-300 Ma magmatic rocks) as determined by U-Pb detrital zircon geochronology. They are as young as Valanginian-Berriasian (~136 Ma, Gradstein et al., 2004) and place a lower limit on the age of formation of the AB. Subsequent intrusions of granitoid plutons, inferred to be ultimately slab-retreat related, form a belt along the far eastern Russian Arctic continental margin onto Seward Peninsula and have yielded a continuous succession of zircon U-Pb ages from ~137-95 Ma (n=28) and a younger suite ~91-82 Ma (n=16). All plutons dated were intruded in an extensional tectonic setting based on their relations to wall-rock deformation. Regional distribution of ages shows a southward migration of the locus of magmatism during Cretaceous time. Basaltic lavas as old as 130 Ma and as young as 80 Ma (40Ar/39Ar)) erupted across the Canadian Arctic Islands, Svalbard and Franz Josef Land and are associated with

  14. The role of ions in the formation and evolution of particles in aircraft plumes

    Science.gov (United States)

    Yu, Fangqun; Turco, Richard P.

    We consider the effects on aircraft plume microphysics of ions generated by chemiionization processes within the engine combustors. Ions provide centers around which molecular clusters rapidly coalesce, thus promoting the formation of electrically charged sulfuric acid/water aerosols. The resulting charged micro-particles exhibit enhanced growth due to condensation and coagulation aided by electrostatic effects. Simulations with a plume microphysics code show that volatile particles observed behind aircraft may be explained by such processes, as long as initial ion concentrations in the exhaust exceed ˜108/cm³. This analysis also suggests that the primary emissions of sulfuric acid (plus sulfur trioxide) should amount to at least 20-30% of the fuel sulfur to explain the observed number of volatile particles >9 nm in diameter. Ionized plume simulations reveal a distinct bimodal aerosol distribution, in which an “ion” mode constitutes the larger “activated” volatile sulfuric acid particles, while a smaller “neutral” mode comprises the residual slowly-growing neutral molecular clusters formed in the highly supersaturated region of the plume.

  15. A global sensitivity analysis of the PlumeRise model of volcanic plumes

    Science.gov (United States)

    Woodhouse, Mark J.; Hogg, Andrew J.; Phillips, Jeremy C.

    2016-10-01

    Integral models of volcanic plumes allow predictions of plume dynamics to be made and the rapid estimation of volcanic source conditions from observations of the plume height by model inversion. Here we introduce PlumeRise, an integral model of volcanic plumes that incorporates a description of the state of the atmosphere, includes the effects of wind and the phase change of water, and has been developed as a freely available web-based tool. The model can be used to estimate the height of a volcanic plume when the source conditions are specified, or to infer the strength of the source from an observed plume height through a model inversion. The predictions of the volcanic plume dynamics produced by the model are analysed in four case studies in which the atmospheric conditions and the strength of the source are varied. A global sensitivity analysis of the model to a selection of model inputs is performed and the results are analysed using parallel coordinate plots for visualisation and variance-based sensitivity indices to quantify the sensitivity of model outputs. We find that if the atmospheric conditions do not vary widely then there is a small set of model inputs that strongly influence the model predictions. When estimating the height of the plume, the source mass flux has a controlling influence on the model prediction, while variations in the plume height strongly effect the inferred value of the source mass flux when performing inversion studies. The values taken for the entrainment coefficients have a particularly important effect on the quantitative predictions. The dependencies of the model outputs to variations in the inputs are discussed and compared to simple algebraic expressions that relate source conditions to the height of the plume.

  16. Sulfur chemistry in a copper smelter plume

    Science.gov (United States)

    Eatough, D. J.; Christensen, J. J.; Eatough, N. I.; Hill, M. W.; Major, T. D.; Mangelson, N. F.; Post, M. E.; Ryder, J. F.; Hansen, L. D.; Meisenheimer, R. G.; Fischer, J. W.

    Sulfur transformation chemistry was studied in the plume of the Utah smelter of Kennecott Copper Corporation from April to October 1977. Samples were taken at up to four locations from 4 to 60 km from the stacks. Data collected at each station included: SO 2 concentration, low-volume collected total paniculate matter, high-volume collected size fractionated paniculate matter, wind velocity and direction, temperature, and relative humidity. Paniculate samples were analyzed for S(IV). sulfate, strong acid, anions, cations, and elemental concentrations using calorimetric, ion Chromatographie, FIXE, ESCA, ion microprobe, and SEM-ion microprobe techniques. The concentration of As in the paniculate matter was used as a conservative plume tracer. The ratios Mo/As, Pb/As, and Zn/As were constant in particulate matter collected at all sampling sites for any particle size. Strong mineral acid was neutralized by background metal oxide and/or carbonate particulates within 40km of the smelter. This neutralization process is limited only by the rate of incorporation of basic material into the plume. Two distinct metal-S(IV) species similar to those observed in laboratory aerosol experiments were found in the plume. The formation of paniculate S(IV) species occurs by interaction of SO 2 (g) with both ambient and plume derived aerosol and is equilibrium controlled. The extent of formation of S(IV) complexes in the aerosol is directly proportional to the SO 2(g) and paniculate (Cu + Fe) concentration and inversely proportional to the paniculate acidity. S(IV) species were stable in collected paniculate matter only in the neutralized material, but with proper sampling techniques could be demonstrated to also be present in very acidic particles at high ambient SO 2(g) concentrations. Reduction of arsenate to arsenite by the aerosol S(IV) complexes during plume transport is suggested. The SO 2(g)-sulfate conversion process in the plume is described by a mechanism which is first order

  17. Microbial populations in contaminant plumes

    Science.gov (United States)

    Haack, Sheridan K.; Bekins, Barbara A.

    Efficient biodegradation of subsurface contaminants requires two elements: (1) microbial populations with the necessary degradative capabilities, and (2) favorable subsurface geochemical and hydrological conditions. Practical constraints on experimental design and interpretation in both the hydrogeological and microbiological sciences have resulted in limited knowledge of the interaction between hydrogeological and microbiological features of subsurface environments. These practical constraints include: (1) inconsistencies between the scales of investigation in the hydrogeological and microbiological sciences, and (2) practical limitations on the ability to accurately define microbial populations in environmental samples. However, advances in application of small-scale sampling methods and interdisciplinary approaches to site investigations are beginning to significantly improve understanding of hydrogeological and microbiological interactions. Likewise, culture-based and molecular analyses of microbial populations in subsurface contaminant plumes have revealed significant adaptation of microbial populations to plume environmental conditions. Results of recent studies suggest that variability in subsurface geochemical and hydrological conditions significantly influences subsurface microbial-community structure. Combined investigations of site conditions and microbial-community structure provide the knowledge needed to understand interactions between subsurface microbial populations, plume geochemistry, and contaminant biodegradation. La biodégradation efficace des polluants souterrains requiert deux éléments: des populations microbiennes possédant les aptitudes nécessaires à la dégradation, et des conditions géochimiques et hydrologiques souterraines favorables. Des contraintes pratiques sur la conception et l'interprétation des expériences à la fois en microbiologie et en hydrogéologie ont conduit à une connaissance limitée des interactions entre les

  18. Riding the wake of a merging galaxy cluster

    CERN Document Server

    Canning, R E A; Hatch, N A; Fabian, A C; Zabludoff, A I; Crawford, C S; King, L J; McNamara, B R; Okamoto, S; Raimundo, S I

    2011-01-01

    Using WHT OASIS integral field unit observations, we report the discovery of a thin plume of ionised gas extending from the brightest cluster galaxy in Abell 2146 to the sub-cluster X-ray cool core which is offset from the BCG by ~37 kpc. The plume is greater than 15 kpc long and less than 3 kpc wide. This plume is unique in that the cluster it is situated in is currently undergoing a major galaxy cluster merger. The brightest cluster galaxy is unusually located behind the X-ray shock front and in the wake of the ram pressure stripped X-ray cool core and evidence for recent disruption to the BCG is observed. We examine the gas and stellar morphology, the gas kinematics of the BCG and their relation to the X-ray gas. We propose that a causal link between the ionised gas plume and the offset X-ray cool core provides the simplest explanation for the formation of the plume. An interaction or merger between the BCG and another cluster galaxy is probably the cause of the offset.

  19. PlumeSat: A Micro-Satellite Based Plume Imagery Collection Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ledebuhr, A.G.; Ng, L.C.

    2002-06-30

    This paper describes a technical approach to cost-effectively collect plume imagery of boosting targets using a novel micro-satellite based platform operating in low earth orbit (LEO). The plume collection Micro-satellite or PlueSat for short, will be capable of carrying an array of multi-spectral (UV through LWIR) passive and active (Imaging LADAR) sensors and maneuvering with a lateral divert propulsion system to different observation altitudes (100 to 300 km) and different closing geometries to achieve a range of aspect angles (15 to 60 degrees) in order to simulate a variety of boost phase intercept missions. The PlumeSat will be a cost effective platform to collect boost phase plume imagery from within 1 to 10 km ranges, resulting in 0.1 to 1 meter resolution imagery of a variety of potential target missiles with a goal of demonstrating reliable plume-to-hardbody handover algorithms for future boost phase intercept missions. Once deployed on orbit, the PlumeSat would perform a series phenomenology collection experiments until expends its on-board propellants. The baseline PlumeSat concept is sized to provide from 5 to 7 separate fly by data collects of boosting targets. The total number of data collects will depend on the orbital basing altitude and the accuracy in delivering the boosting target vehicle to the nominal PlumeSat fly-by volume.

  20. Coronal Plumes in the Fast Solar Wind

    Science.gov (United States)

    Velli, Marco; Lionello, Roberto; Linker, Jon A.; Mikic, Zoran

    2011-01-01

    The expansion of a coronal hole filled with a discrete number of higher density coronal plumes is simulated using a time-dependent two-dimensional code. A solar wind model including an exponential coronal heating function and a flux of Alfven waves propagating both inside and outside the structures is taken as a basic state. Different plasma plume profiles are obtained by using different scale heights for the heating rates. Remote sensing and solar wind in situ observations are used to constrain the parameter range of the study. Time dependence due to plume ignition and disappearance is also discussed. Velocity differences of the order of approximately 50 km/s, such as those found in microstreams in the high-speed solar wind, may be easily explained by slightly different heat deposition profiles in different plumes. Statistical pressure balance in the fast wind data may be masked by the large variety of body and surface waves which the higher density filaments may carry, so the absence of pressure balance in the microstreams should not rule out their interpretation as the extension of coronal plumes into interplanetary space. Mixing of plume-interplume material via the Kelvin-Helmholtz instability seems to be possible within the parameter ranges of the models defined here, only at large di stances from the Sun, beyond 0.2-0.3 AU. Plasma and composition measurements in the inner heliosphere, such as those which will become available with Solar Orbiter and Solar Probe Plus, should therefore definitely be able to identify plume remnants in the solar wind.

  1. Topside-plasmasphere electron density profiles model by using AIS ionosonde measurements and calibrates GPS TEC data

    Science.gov (United States)

    Cesaroni, Claudio; Scotto, Carlo; Ippolito, Alessandro; Ciraolo, Luigi

    2013-04-01

    The Upper Atmosphere Physics group at INGV (Istituto Nazionale di Geofisica e Vulcanologia) developed Autoscala, a computer program for automatic scaling of the critical frequency foF2 and other ionospheric parameters derived from ionograms. Autoscala includes a routine that automatically estimates the electron density profile below F layer peak height hmF2, by adjusting the parameters of a model according to the recorded ionogram [Scotto (2009)]. By integrating this profile we can estimate bottom-side total electron content (bTEC). By means of a calibration technique [Ciraolo et al. (2007)], we are able to obtain calibrated vertical TEC (vTEC) values from GPS measurements over a receiver station. This method permits to estimate biases of the received signal due to transmitter-receiver hardware configuration. These biases must be eliminated from the GPS data in order to calibrate the experimental slant total electron content (sTEC) along the satellite-receiver line-of-sight (LoS). The difference between vTEC and bottom-side TEC (bTEC) permits to evaluate electron content of the topside ionospheric region (tTEC). Starting from tTEC, bottom-side parameters (foF2, hmF2, scale height at hmF2) obtained by ionosonde and O+ - H+ transition level, we can solve a system of equations based on different ionospheric profiler (Chapman, sech-squared and exponential) the solution of which provides ion scale height [Stankov et al. (2003)]. This last factor is sufficient to establish the vertical distribution of electrons in topside and plasmasphere regions. Obtained vertical profiles could be used to develop a new model for real time estimation of TEC and topside electron density distribution. References: Scotto, C. (2009). Electron density profile calculation technique for Autoscala ionogram analysis. Advances in Space Research, 44(6), 756-766. doi:10.1016/j.asr.2009.04.037 Ciraolo, L., et al. "Calibration errors on experimental slant total electron content (TEC) determined with

  2. Wind-Forced Baroclinic Beta-Plumes

    Science.gov (United States)

    Belmadani, A.; Maximenko, N. A.; Melnichenko, O.; Schneider, N.; Di Lorenzo, E.

    2011-12-01

    A planetary beta-plume is a classical example of oceanic circulation induced by a localized vorticity source or sink that allows an analytical description in simplistic cases. Its barotropic structure is a zonally-elongated, gyre-like cell governed by the Sverdrup circulation on the beta-plane. The dominant zonal currents, found west of the source/sink, are often referred to as zonal jets. This simple picture describes the depth-integrated flow. Previous studies have investigated beta-plumes in a reduced-gravity framework or using other simple models with a small number of vertical layers, thereby lacking representation of the vertical structure. In addition, most previous studies use a purely linear regime without considering the role of eddies. However, these jets are often associated with strong lateral shear that makes them unstable under increased forcing. The circulation in such a nonlinear regime may involve eddy-mean flow interactions, which modify the time-averaged circulation. Here, the baroclinic structures of linear and nonlinear wind-forced beta-plumes are studied using a continuously-stratified, primitive equation, eddy-permitting ocean model (ROMS). The model is configured in an idealized rectangular domain for the subtropical ocean with a flat bottom. The surface wind forcing is a steady anticyclonic Gaussian wind vortex, which provides a localized vorticity source in the center of the domain. The associated wind stress curl and Ekman pumping comprise downwelling in the vortex center surrounded by a ring of weaker upwelling. Under weak forcing, the simulated steady-state circulation corresponds well with a theoretical linear beta-plume. While its depth-integrated transport exhibits a set of zonal jets, consistent with Sverdrup theory, the baroclinic structure of the plume is remarkably complex. Relatively fast westward decay of the surface currents occurs simultaneously with the deepening of the lower boundary of the plume. This deepening suggests

  3. Confirmation of Water Plumes on Europa

    Science.gov (United States)

    Sparks, William

    Evidence was found for plumes of water ice venting from the polar regions of Europa (Roth et al 2014a) - FUV detection of off-limb line emission from the dissociation products of water. We find additional evidence for the presence of ice plumes on Europa from HST transit imaging observations (Sparks et al 2016). The evidence for plumes remains marginal, 4-sigma, and there is considerable debate as to their reality. SOFIA can potentially resolve this issue with an unambiguous direct detection of water vapor using EXES. Detection of the fundamental vibrational mode of water vapor at 6 micron, as opposed to the atomic constituents of water, would prove that the plumes exist and inform us of their physical chemistry through quantitative consideration of the balance between water vapor and its dissociation products, hydrogen and oxygen. We propose to obtain spectra of the leading and trailing hemispheres separately, with trailing as the higher priority. These provide two very different physical environments and plausibly different degrees of activity. If the plumes of Europa arise from the deep ocean, we have gained access to probably the most astrobiologically interesting location in the Solar System, and clarify an issue of major strategic importance in NASAs planning for its multi-billion dollar mission to Europa.

  4. Modelling of aerosol processes in plumes

    Energy Technology Data Exchange (ETDEWEB)

    Lazaridis, M.; Isukapalli, S.S.; Georgopoulos, P.G. [Norwegian Institute of Air Research, Kjeller (Norway)

    2001-07-01

    A modelling platform for studying photochemical gaseous and aerosol phase processes from localized (e.g., point) sources has been presented. The current approach employs a reactive plume model which extends the regulatory model RPM-IV by incorporating aerosol processes and heterogeneous chemistry. The physics and chemistry of elemental carbon, organic carbon, sulfate, nitrate, ammonium material of aerosols are treated and attributed to the PM size distribution. A modified version of the carbon bond IV chemical mechanism is included to model the formation of organic aerosol. Aerosol dynamics modeled include mechanisms of nucleation, condensation, dry deposition and gas/particle partitioning of organic matter. The model is first applied to a number of case studies involving emissions from point sources and sulfate particle formation in plumes. Model calculations show that homogeneous nucleation is an efficient process for new particle formation in plumes, in agreement with previous field studies and theoretical predictions. In addition, the model is compared with field data from power plant plumes with satisfactory predictions against gaseous species and total sulphate mass measurements. Finally, the plume model is applied to study secondary organic matter formation due to various emission categories such as vehicles and the oil production sector.

  5. Intermittent heat instabilities in an air plume

    Science.gov (United States)

    Le Mouël, Jean-Louis; Kossobokov, Vladimir G.; Perrier, Frederic; Morat, Pierre

    2016-08-01

    We report the results of heating experiments carried out in an abandoned limestone quarry close to Paris, in an isolated room of a volume of about 400 m3. A heat source made of a metallic resistor of power 100 W was installed on the floor of the room, at distance from the walls. High-quality temperature sensors, with a response time of 20 s, were fixed on a 2 m long bar. In a series of 24 h heating experiments the bar had been set up horizontally at different heights or vertically along the axis of the plume to record changes in temperature distribution with a sampling time varying from 20 to 120 s. When taken in averages over 24 h, the temperatures present the classical shape of steady-state plumes, as described by classical models. On the contrary, the temperature time series show a rich dynamic plume flow with intermittent trains of oscillations, spatially coherent, of large amplitude and a period around 400 s, separated by intervals of relative quiescence whose duration can reach several hours. To our knowledge, no specific theory is available to explain this behavior, which appears to be a chaotic interaction between a turbulent plume and a stratified environment. The observed behavior, with first-order factorization of a smooth spatial function with a global temporal intermittent function, could be a universal feature of some turbulent plumes in geophysical environments.

  6. Near field characteristics of buoyant helium plumes

    Indian Academy of Sciences (India)

    Kuchimanchi K Bharadwaj; Debopam Das; Pavan K Sharma

    2015-05-01

    Puffing and entrainment characteristics of helium plumes emanating out into ambient air from a circular orifice are investigated in the present study. Velocity and density fields are measured across a diametric plane using Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) respectively in phase resolved manner. Experiments are performed in Froude numbers range 0.2–0.4 and for Reynolds numbers 58–248. Puffing frequency measurements reveal that the plume puffing frequencies are insensitive to the plume exit conditions, since the instability is buoyancy driven. The frequencies obtained in the present case are in agreement with frequencies obtained by Cetegen & Kasper (1996) for plumes originating from circular nozzles of various L/D ratios. Velocity and density measurements reveal that toroidal vortex formed during a puffing cycle entrains ambient air as it traverses downstream and this periodic engulfment governs the entrainment mechanism in pulsating plumes. The obtained velocity and density fields are used to calculate mass entrainment rates. It is revealed that though the flow is unsteady, the contribution of unsteady term in mass conservation to entrainment is negligible, and it becomes zero over a puff cycle. Finally, an empirical relation for variation of mass entrainment with height has been proposed, in which the non-dimensional mass entrainment is found to follow a power law with the non-dimensional height.

  7. Mantle plumes in the vicinity of subduction zones

    Science.gov (United States)

    Mériaux, C. A.; Mériaux, A.-S.; Schellart, W. P.; Duarte, J. C.; Duarte, S. S.; Chen, Z.

    2016-11-01

    We present three-dimensional deep-mantle laboratory models of a compositional plume within the vicinity of a buoyancy-driven subducting plate with a fixed trailing edge. We modelled front plumes (in the mantle wedge), rear plumes (beneath the subducting plate) and side plumes with slab/plume systems of buoyancy flux ratio spanning a range from 2 to 100 that overlaps the ratios in nature of 0.2-100. This study shows that 1) rising side and front plumes can be dragged over thousands of kilometres into the mantle wedge, 2) flattening of rear plumes in the trench-normal direction can be initiated 700 km away from the trench, and a plume material layer of lesser density and viscosity can ultimately almost entirely underlay a retreating slab after slab/plume impact, 3) while side and rear plumes are not tilted until they reach ∼600 km depth, front plumes can be tilted at increasing depths as their plume buoyancy is lessened, and rise at a slower rate when subjected to a slab-induced downwelling, 4) rear plumes whose buoyancy flux is close to that of a slab, can retard subduction until the slab is 600 km long, and 5) slab-plume interaction can lead to a diversity of spatial plume material distributions into the mantle wedge. We discuss natural slab/plume systems of the Cascadia/Bowie-Cobb, and Nazca/San Felix-Juan Fernandez systems on the basis of our experiments and each geodynamic context and assess the influence of slab downwelling at depths for the starting plumes of Java, Coral Sea and East Solomon. Overall, this study shows how slab/plume interactions can result in a variety of geological, geophysical and geochemical signatures.

  8. The 2016 Case for Mantle Plumes and a Plume-Fed Asthenosphere (Augustus Love Medal Lecture)

    Science.gov (United States)

    Morgan, Jason P.

    2016-04-01

    The process of science always returns to weighing evidence and arguments for and against a given hypothesis. As hypotheses can only be falsified, never universally proved, doubt and skepticism remain essential elements of the scientific method. In the past decade, even the hypothesis that mantle plumes exist as upwelling currents in the convecting mantle has been subject to intense scrutiny; from geochemists and geochronologists concerned that idealized plume models could not fit many details of their observations, and from seismologists concerned that mantle plumes can sometimes not be 'seen' in their increasingly high-resolution tomographic images of the mantle. In the place of mantle plumes, various locally specific and largely non-predictive hypotheses have been proposed to explain the origins of non-plate boundary volcanism at Hawaii, Samoa, etc. In my opinion, this debate has now passed from what was initially an extremely useful restorative from simply 'believing' in the idealized conventional mantle plume/hotspot scenario to becoming an active impediment to our community's ability to better understand the dynamics of the solid Earth. Having no working hypothesis at all is usually worse for making progress than having an imperfect and incomplete but partially correct one. There continues to be strong arguments and strong emerging evidence for deep mantle plumes. Furthermore, deep thermal plumes should exist in a mantle that is heated at its base, and the existence of Earth's (convective) geodynamo clearly indicates that heat flows from the core to heat the mantle's base. Here I review recent seismic evidence by French, Romanowicz, and coworkers that I feel lends strong new observational support for the existence of deep mantle plumes. I also review recent evidence consistent with the idea that secular core cooling replenishes half the mantle's heat loss through its top surface, e.g. that the present-day mantle is strongly bottom heated. Causes for

  9. Simple model of a cooling tower plume

    Science.gov (United States)

    Jan, Cizek; Jiri, Nozicka

    2016-06-01

    This article discusses the possibilities in the area of modeling of the so called cooling tower plume emergent at operating evaporating cooling systems. As opposed to recent publication, this text focuses on the possibilities of a simplified analytic description of the whole problem where this description shall - in the future - form the base of a calculation algorithms enabling to simulate the efficiency of systems reducing this cooling tower plume. The procedure is based on the application of basic formula for the calculation of the velocity and concentration fields in the area above the cooling tower. These calculation is then used to determine the form and the total volume of the plume. Although this approach does not offer more exact results, it can provide a basic understanding of the impact of individual quantities relating to this problem.

  10. A collisionless plasma thruster plume expansion model

    Science.gov (United States)

    Merino, Mario; Cichocki, Filippo; Ahedo, Eduardo

    2015-06-01

    A two-fluid model of the unmagnetized, collisionless far region expansion of the plasma plume for gridded ion thrusters and Hall effect thrusters is presented. The model is integrated into two semi-analytical solutions valid in the hypersonic case. These solutions are discussed and compared against the results from the (exact) method of characteristics; the relative errors in density and velocity increase slowly axially and radially and are of the order of 10-2-10-3 in the cases studied. The plasma density, ion flux and ambipolar electric field are investigated. A sensitivity analysis of the problem parameters and initial conditions is carried out in order to characterize the far plume divergence angle in the range of interest for space electric propulsion. A qualitative discussion of the physics of the secondary plasma plume is also provided.

  11. Numerical and approximate solutions for plume rise

    Science.gov (United States)

    Krishnamurthy, Ramesh; Gordon Hall, J.

    Numerical and approximate analytical solutions are compared for turbulent plume rise in a crosswind. The numerical solutions were calculated using the plume rise model of Hoult, Fay and Forney (1969, J. Air Pollut. Control Ass.19, 585-590), over a wide range of pertinent parameters. Some wind shear and elevated inversion effects are included. The numerical solutions are seen to agree with the approximate solutions over a fairly wide range of the parameters. For the conditions considered in the study, wind shear effects are seen to be quite small. A limited study was made of the penetration of elevated inversions by plumes. The results indicate the adequacy of a simple criterion proposed by Briggs (1969, AEC Critical Review Series, USAEC Division of Technical Information extension, Oak Ridge, Tennesse).

  12. Properties of industrial dense gas plumes

    Science.gov (United States)

    Shaver, E. M.; Forney, L. J.

    Hazardous gases and vapors are often discharged into the atmosphere from industrial plants during catastrophic events (e.g. Union Carbide incident in Bhopal, India). In many cases the discharged components are more dense than air and settle to the ground surface downstream from the stack exit. In the present paper, the buoyant plume model of Hoult, Fay and Forney (1969, J. Air Pollut. Control Ass. 19, 585-590.) has been altered to predict the properties of hazardous discharges. In particular, the plume impingement point, radius and concentration are predicted for typical stack exit conditions, wind speeds and temperature profiles. Asymptotic expressions for plume properties at the impingement point are also derived for a constant crosswind and neutral temperature profile. These formulae are shown to be useful for all conditions.

  13. Modeling the Enceladus plume--plasma interaction

    CERN Document Server

    Fleshman, B L; Bagenal, F

    2010-01-01

    We investigate the chemical interaction between Saturn's corotating plasma and Enceladus' volcanic plumes. We evolve plasma as it passes through a prescribed H2O plume using a physical chemistry model adapted for water-group reactions. The flow field is assumed to be that of a plasma around an electrically-conducting obstacle centered on Enceladus and aligned with Saturn's magnetic field, consistent with Cassini magnetometer data. We explore the effects on the physical chemistry due to: (1) a small population of hot electrons; (2) a plasma flow decelerated in response to the pickup of fresh ions; (3) the source rate of neutral H2O. The model confirms that charge exchange dominates the local chemistry and that H3O+ dominates the water-group composition downstream of the Enceladus plumes. We also find that the amount of fresh pickup ions depends heavily on both the neutral source strength and on the presence of a persistent population of hot electrons.

  14. The CuSPED Mission: CubeSat for GNSS Sounding of the Ionosphere-Plasmasphere Electron Density

    Science.gov (United States)

    Gross, Jason N.; Keesee, Amy M.; Christian, John A.; Gu, Yu; Scime, Earl; Komjathy, Attila; Lightsey, E. Glenn; Pollock, Craig J.

    2016-01-01

    The CubeSat for GNSS Sounding of Ionosphere-Plasmasphere Electron Density (CuSPED) is a 3U CubeSat mission concept that has been developed in response to the NASA Heliophysics program's decadal science goal of the determining of the dynamics and coupling of the Earth's magnetosphere, ionosphere, and atmosphere and their response to solar and terrestrial inputs. The mission was formulated through a collaboration between West Virginia University, Georgia Tech, NASA GSFC and NASA JPL, and features a 3U CubeSat that hosts both a miniaturized space capable Global Navigation Satellite System (GNSS) receiver for topside atmospheric sounding, along with a Thermal Electron Capped Hemispherical Spectrometer (TECHS) for the purpose of in situ electron precipitation measurements. These two complimentary measurement techniques will provide data for the purpose of constraining ionosphere-magnetosphere coupling models and will also enable studies of the local plasma environment and spacecraft charging; a phenomenon which is known to lead to significant errors in the measurement of low-energy, charged species from instruments aboard spacecraft traversing the ionosphere. This paper will provide an overview of the concept including its science motivation and implementation.

  15. Effects of meteorological conditions on spore plumes

    Science.gov (United States)

    Burch, M.; Levetin, E.

    2002-05-01

    Fungal spores are an ever-present component of the atmosphere, and have long been known to trigger asthma and hay fever symptoms in sensitive individuals. The atmosphere around Tulsa has been monitored for airborne spores and pollen with Burkard spore traps at several sampling stations. This study involved the examination of the hourly spore concentrations on days that had average daily concentrations near 50,000 spores/m3 or greater. Hourly concentrations of Cladosporium, Alternaria, Epicoccum, Curvularia, Pithomyces, Drechslera, smut spores, ascospores, basidiospores, other, and total spores were determined on 4 days at three sites and then correlated with hourly meteorological data including temperature, rainfall, wind speed, dew point, air pressure, and wind direction. On each of these days there was a spore plume, a phenomenon in which spore concentrations increased dramatically over a very short period of time. Spore plumes generally occurred near midday, and concentrations were seen to increase from lows around 20,000 total spores/m3 to highs over 170,000 total spores/m3 in 2 h. Multiple regression analysis of the data indicated that increases in temperature, dew point, and air pressure correlated with the increase in spore concentrations, but no single weather variable predicted the appearance of a spore plume. The proper combination of changes in these meteorological parameters that result in a spore plume may be due to the changing weather conditions associated with thunderstorms, as on 3 of the 4 days when spore plumes occurred there were thunderstorms later that evening. The occurrence of spore plumes may have clinical significance, because other studies have shown that sensitization to certain spore types can occur during exposure to high spore concentrations.

  16. Cassini Radio Occultation by Enceladus Plume

    Science.gov (United States)

    Kliore, A.; Armstrong, J.; Flasar, F.; French, R.; Marouf, E.; Nagy, A.; Rappaport, N.; McGhee, C.; Schinder, P.; Anabtawi, A.; Asmar, S.; Barbinis, E.; Fleischman, D.; Goltz, G.; Aguilar, R.; Rochblatt, D.

    2006-12-01

    A fortuitous Cassini radio occultation by Enceladus plume occurs on September 15, 2006. The occultation track (the spacecraft trajectory in the plane of the sky as viewed from the Earth) has been designed to pass behind the plume (to pass above the south polar region of Enceladus) in a roughly symmetrical geometry centered on a minimum altitude above the surface of about 20 km. The minimum altitude was selected primarily to ensure probing much of the plume with good confidence given the uncertainty in the spacecraft trajectory. Three nearly-pure sinusoidal signals of 0.94, 3.6, and 13 cm-wavelength (Ka-, X-, and S-band, respectively) are simultaneously transmitted from Cassini and are monitored at two 34-m Earth receiving stations of the Deep Space Network (DSN) in Madrid, Spain (DSS-55 and DSS-65). The occultation of the visible plume is extremely fast, lasting less than about two minutes. The actual observation time extends over a much longer time interval, however, to provide a good reference baseline for potential detection of signal perturbations introduced by the tenuous neutral and ionized plume environment. Given the likely very small fraction of optical depth due to neutral particles of sizes larger than about 1 mm, detectable changes in signal intensity is perhaps unlikely. Detection of plume plasma along the radio path as perturbations in the signals frequency/phase is more likely and the magnitude will depend on the electron columnar density probed. The occultation time occurs not far from solar conjunction time (Sun-Earth-probe angle of about 33 degrees), causing phase scintillations due to the solar wind to be the primary limiting noise source. We estimate a delectability limit of about 1 to 3E16 electrons per square meter columnar density assuming about 100 seconds integration time. Potential measurement of the profile of electron columnar density along the occultation track is an exciting prospect at this time.

  17. Observation of Dust and Smoke Plume Transport and Impact on Remote Sensing of Air Quality in New York City

    Science.gov (United States)

    Moshary, F.; Wu, Y.; Han, Z. T.; Nazmi, C.; Gross, B.

    2015-12-01

    Long-range transport of aloft aerosol plumes affects both air quality and climate on regional and continental scales. Asian dust impacts on the western US and Canada have been extensively analyzed, yet such quantitative demonstrations are not well documented in the northeastern US. Similarly, episodes of continental transport of smoke plumes from forest fires in western US and Canada impact visibility and air quality in the US east coast. In this study, we present the synergistic observation of transported dust and smoke aerosol plumes in New York City (NYC, 40.821ºN, 73.949ºW), using a combination of a ground-based multiple-wavelength lidar, a CIMEL sunphotometer/radiometer, satellite sensors such as CALIOP and MODIS/VIIRS, and NAAPS aerosol forecast model. We show case studies of trans-Pacific Asian dust transport to the northeast US driven by the strong western or polar jets. The potential impact of the plumes on the local air quality is indicated by the plumes mixing down into boundary layer and the coincident increase of the ground PM measurement. Using multi-year lidar and sunphotometer observations, range-resolved monthly occurrence frequency of aloft aerosol plumes and modification of local aerosol optical properties are presented. The transport paths and the optical properties of aerosol for each clustered path are characterized. We further demonstrate the impact of these aloft plumes on the surface PM2.5 estimates from MODIS and VIIRS derived aerosol optical depth (AOD), and observe that when the aloft plumes-layer AODs are filtered out using lidar, the correlation between AOD-PM2.5 is much improved.

  18. Plume head - trench interaction: impact on subduction dynamics

    Science.gov (United States)

    Betts, P. G.; Moresi, L. N.; Mason, W. G.; Willis, D.

    2013-12-01

    The geologic record provides numerous examples where plumes and their associated buoyancy swell have disrupted convergent plate margins. These interactions have produced a variety of responses in the overriding plate including transient episodes of arc amagmatism, transient episodes of crustal shortening followed by plume-related magmatism in the overriding plate. The latter observation implies the plume must have transitioned from the subducting plate to the overriding plate. We present several 3D Underworld numerical models of plume heads of variable dimension and buoyancy interacting with a subduction trench. The models indicate that plume heads impact enormously on trench geometry. Arcuate trenches are created as the trench retreats around the edges of the plume head, whereas trench advance occurs in front of the plume resulting in transient crustal shortening in the overriding plate. Stalling of subduction when the plume head impacts the trench causes slab windowing. The size of the slab window is dependent on the size and buoyancy of the plume. The creation of the slab window provides a potential conduit for plume migration to the overriding plate. Alternatively, the plume head may be transferred to the overriding plate as subduction is re-established behind the plume. Models with "strong" slabs, characterized by high yield strengths, display different behavior. Plume-heads are entrained in the slab and are subducted without the development of a slab window.

  19. EUV Sunspot Plumes Observed with SOHO

    CERN Document Server

    Maltby, P; Brekke, P; Haugan, S V H; Kjeldseth-Moe, O; Wikstøl, O; Rimmele, T R; Wikstøl, O

    1998-01-01

    Bright EUV sunspot plumes have been observed in five out of nine sunspot regions with the Coronal Diagnostic Spectrometer -- CDS on SOHO. In the other four regions the brightest line emissions may appear inside the sunspot but are mainly concentrated in small regions outside the sunspot areas. These results are in contrast to those obtained during the Solar Maximum Mission, but are compatible with the Skylab mission results. The present observations show that sunspot plumes are formed in the upper part of the transition region, occur both in magnetic unipolar-- and bipolar regions, and may extend from the umbra into the penumbra.

  20. Halogen Chemistry in Volcanic Plumes (Invited)

    Science.gov (United States)

    Roberts, Tjarda

    2017-04-01

    Volcanoes release vast amounts of gases and particles in the atmosphere. Volcanic halogens (HF, HCl, HBr, HI) are co-emitted alongside SO2, and observations show rapid formation of BrO and OClO in the plume as it disperses into the troposphere. The development of 1D and Box models (e.g. PlumeChem) that simulate volcanic plume halogen chemistry aims to characterise how volcanic reactive halogens form and quantify their atmospheric impacts. Following recent advances, these models can broadly reproduce the observed downwind BrO/SO2 ratios using "bromine-explosion" chemistry schemes, provided they use a "high-temperature initialisation" to inject radicals (OH, Cl, Br and possibly NOx) which "kick-start" the low-temperature chemistry cycles that convert HBr into reactive bromine (initially as Br2). The modelled rise in BrO/SO2 and subsequent plateau/decline as the plume disperses downwind reflects cycling between reactive bromine, particularly Br-BrO, and BrO-HOBr-BrONO2. BrCl is produced when aerosol becomes HBr-depleted. Recent model simulations suggest this mechanism for reactive chlorine formation can broadly account for OClO/SO2 reported at Mt Etna. Predicted impacts of volcanic reactive halogen chemistry include the formation of HNO3 from NOx and depletion of ozone. This concurs with HNO3 widely reported in volcanic plumes (although the source of NOx remains under question), as well as observations of ozone depletion reported in plumes from several volcanoes (Mt Redoubt, Mt Etna, Eyjafjallajokull). The plume chemistry can transform mercury into more easily deposited and potentially toxic forms, for which observations are limited. Recent incorporation of volcanic halogen chemistry in a 3D regional model of degassing from Ambrym (Vanuatu) also predicts how halogen chemistry causes depletion of OH to lengthen the SO2 lifetime, and highlights the potential for halogen transport from the troposphere to the stratosphere. However, the model parameter-space is vast and

  1. New method for calculation of integral characteristics of thermal plumes

    DEFF Research Database (Denmark)

    Zukowska, Daria; Popiolek, Zbigniew; Melikov, Arsen Krikor

    2008-01-01

    A method for calculation of integral characteristics of thermal plumes is proposed. The method allows for determination of the integral parameters of plumes based on speed measurements performed with omnidirectional low velocity thermoanemometers. The method includes a procedure for calculation...

  2. New method for calculation of integral characteristics of thermal plumes

    DEFF Research Database (Denmark)

    2008-01-01

    A method for calculation of integral characteristics of thermal plumes is proposed. The method allows for determination of the integral parameters of plumes based on speed measurements performed with omnidirectional low velocity thermoanemometers. The method includes a procedure for calculation...

  3. Background Radiance Estimation for Gas Plume Quantification for Airborne Hyperspectral Thermal Imaging

    Directory of Open Access Journals (Sweden)

    Ramzi Idoughi

    2016-01-01

    Full Text Available Hyperspectral imaging in the long-wave infrared (LWIR is a mean that is proving its worth in the characterization of gaseous effluent. Indeed the spectral and spatial resolution of acquisition instruments is steadily decreasing, making the gases characterization increasingly easy in the LWIR domain. The majority of literature algorithms exploit the plume contribution to the radiance corresponding to the difference of radiance between the plume-present and plume-absent pixels. Nevertheless, the off-plume radiance is unobservable using a single image. In this paper, we propose a new method to retrieve trace gas concentration from airborne infrared hyperspectral data. More particularly the outlined method improves the existing background radiance estimation approach to deal with heterogeneous scenes corresponding to industrial scenes. It consists in performing a classification of the scene and then applying a principal components analysis based method to estimate the background radiance on each cluster stemming from the classification. In order to determine the contribution of the classification to the background radiance estimation, we compared the two approaches on synthetic data and Telops Fourier Transform Spectrometer (FTS Imaging Hyper-Cam LW airborne acquisition above ethylene release. We finally show ethylene retrieved concentration map and estimate flow rate of the ethylene release.

  4. Forensic investigation of a chromium(VI) groundwater plume in Thiva, Greece

    Energy Technology Data Exchange (ETDEWEB)

    Panagiotakis, I. [National Technical Univ. of Athens, Zografou (Greece); Dermatas, D. [National Technical Univ. of Athens, Zografou (Greece); Vatseris, C. [Intergeo-Environmental Technology Ltd., Thessaloniki (Greece); Chrysochoou, M. [Univ. of Connecticut, Storrs, CT (United States); Papassiopi, N. [National Technical Univ. of Athens, Zografou (Greece); Xenidis, A. [National Technical Univ. of Athens, Zografou (Greece); Vaxevanidou, K. [National Technical Univ. of Athens, Zografou (Greece)

    2015-01-01

    We conducted a forensic investigation with the aim of decoupling the contribution of geogenic and anthropogenic Cr(VI) sources in the wider area of Thiva. Groundwater and topsoil samples were collected from two Cr(VI) groundwater plumes of 160 μg/L and 75 μg/L. A series of evidence support the view that the origin of Cr(VI) detected in groundwater is mainly geogenic. These are: (a) the presence of Cr in topsoil of the wider area, (b) the moderate Cr(VI) groundwater concentrations, (c) the high Ni levels within the Cr(VI) plumes, (d) the predominance of Mn(IV), which is a prerequisite for Cr(III) oxidation to Cr(VI), and (e) the absence of co-contaminants. This study also revealed that, although both Cr(VI) plumes are clearly of geogenic origin, the plume with the elevated Cr(VI) values, in the north of Thiva town, exhibits also an anthropogenic component, which can potentially be attributed to the alkaline environment associated with the old uncontrolled landfill of Thiva and the industrial cluster located in this area.

  5. Integrated Observation of Aerosol Plumes Transport and Impacts on the Air Quality Remote Sensing in the Northeast U.S.

    Directory of Open Access Journals (Sweden)

    Wu Yonghua

    2016-01-01

    Full Text Available In this paper, we present a cluster analysis of plume transport paths to New York City (NYC, 40.821ºN, 73.949ºW for the 8-year period during 2006-2013. We also show cases of such aloft aerosol plumes intrusion and mixing into the boundary layer (PBL and the impact on local air quality. Range-resolved monthly occurrence frequency and modification of local aerosol optical properties are presented. The NOAA-HYSPLIT cluster analysis indicates 6 main transport paths; and the optical properties (optical depth-AOD, Angstrom exponent-AE and single scatter albedo-SSA of aerosol for each cluster are characterized. We further illustrate the impact of these aloft plumes on the satellite MODIS estimate of ground PM2.5 levels and observe that when the aloft plumes-layer AODs are filtered out using lidar, the correlation of MODIS AOD-PM2.5 can be much improved.

  6. Visualising volcanic gas plumes with virtual globes

    Science.gov (United States)

    Wright, T. E.; Burton, M.; Pyle, D. M.; Caltabiano, T.

    2009-09-01

    The recent availability of small, cheap ultraviolet spectrometers has facilitated the rapid deployment of automated networks of scanning instruments at several volcanoes, measuring volcanic SO 2 gas flux at high frequency. These networks open up a range of other applications, including tomographic reconstruction of the gas distribution which is of potential use for both risk mitigation, particularly to air traffic, and environmental impact modelling. Here we present a methodology for visualising reconstructed plumes using virtual globes, such as Google Earth, which allows animations of the evolution of the gas plume to be displayed and easily shared on a common platform. We detail the process used to convert tomographically reconstructed cross-sections into animated gas plume models, describe how this process is automated and present results from the scanning network around Mt. Etna, Sicily. We achieved an average rate of one frame every 12 min, providing a good visual representation of the plume which can be examined from all angles. In creating these models, an approximation to turbulent diffusion in the atmosphere was required. To this end we derived the value of the turbulent diffusion coefficient for quiescent conditions near Etna to be around 200- 500m2s-1.

  7. Detection of contaminant plumes released from landfills

    Science.gov (United States)

    Yenigül, N. B.; Hendsbergen, A. T.; Elfeki, A. M. M.; Dekking, F. M.

    2006-06-01

    Contaminant leaks released from landfills are a significant threat to groundwater quality. The groundwater detection monitoring systems installed in the vicinity of such facilities are vital. In this study the detection probability of a contaminant plume released from a landfill has been investigated by means of both a simulation and an analytical model for both homogeneous and heterogeneous aquifer conditions. The results of the two models are compared for homogeneous aquifer conditions to illustrate the errors that might be encountered with the simulation model. For heterogeneous aquifer conditions contaminant transport is modelled by an analytical model using effective (macro) dispersivities. The results of the analysis show that the simulation model gives the concentration values correctly over most of the plume length for homogeneous aquifer conditions, and that the detection probability of a contaminant plume at given monitoring well locations match quite well. For heterogeneous aquifer conditions the approximating analytical model based on effective (macro) dispersivities yields the average concentration distribution satisfactorily. However, it is insufficient in monitoring system design since the discrepancy between the detection probabilities of contaminant plumes at given monitoring well locations computed by the two models is significant, particularly with high dispersivity and heterogeneity.

  8. Diagnostics of laser ablated plasma plumes

    DEFF Research Database (Denmark)

    Amoruso, S.; Toftmann, B.; Schou, Jørgen;

    2004-01-01

    The effect of an ambient gas on the expansion dynamics of laser ablated plasmas has been studied for two systems by exploiting different diagnostic techniques. First, the dynamics of a MgB2 laser produced plasma plume in an Ar atmosphere has been investigated by space-and time-resolved optical...

  9. Ablation plume dynamics in a background gas

    DEFF Research Database (Denmark)

    Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

    2010-01-01

    The expansion of a plume in a background gas of pressure comparable to that used in pulsed laser deposition (PLD) has been analyzed in terms of the model of Predtechensky and Mayorov (PM). This approach gives a relatively clear and simple description of the essential hydrodynamics during the expa...

  10. DSMC simulation of Europa water vapor plumes

    Science.gov (United States)

    Berg, J. J.; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M.

    2016-10-01

    A computational investigation of the physics of water vapor plumes on Europa was performed with a focus on characteristics relevant to observation and spacecraft mission operations. The direct simulation Monte Carlo (DSMC) method was used to model the plume expansion assuming a supersonic vent source. The structure of the plume was determined, including the number density, temperature, and velocity fields. The possibility of ice grain growth above the vent was considered and deemed probable for large (diameter > ∼20 m) vents at certain Mach numbers. Additionally, preexisting grains of three diameters (0.1, 1, 50 μm) were included and their trajectories examined. A preliminary study of photodissociation of H2O into OH and H was performed to demonstrate the behavior of daughter species. A set of vent parameters was evaluated including Mach number (Mach 2, 3, 5), reduced temperature as a proxy for flow energy loss to the region surrounding the vent, and mass flow rate. Plume behavior was relatively insensitive to these factors, with the notable exception of mass flow rate. With an assumed mass flow rate of ∼1000 kg/s, a canopy shock occurred and a maximum integrated line of sight column density of ∼1020 H2O molecules/m2 was calculated, comparing favorably with observation (Roth et al., 2014a).

  11. Propagation of light through ship exhaust plumes

    NARCIS (Netherlands)

    Iersel, M. van; Mack, A.; Eijk, A.M.J. van; Schleijpen, H.M.A.

    2014-01-01

    Looking through the atmosphere, it is sometimes difficult to see the details of an object. Effects like scintillation and blur are the cause of these difficulties. Exhaust plumes of e.g. a ship can cause extreme scintillation and blur, making it even harder to see the details of what lies behind the

  12. Plume dynamics in heterogeneous porous media

    Science.gov (United States)

    Neufeld, Jerome A.; Huppert, Herbert E.

    2008-11-01

    Buoyancy driven flows in layered porous media are present in many geological settings and play an important role in the mixing of fluids, from the dispersal of pollutants in underground aquifers to enhanced oil recovery techniques and, of more recent importance, the sequestration of carbon dioxide (CO2). Seismic images of the rise of a buoyant CO2 plume at Sleipner in the North Sea indicate that these plumes are greatly influenced by a vertical array of thin lenses of relatively low permeability material. We model propagation of CO2 at each layer as a gravity current in a porous medium which propagates along, and drains through, a thin, low permeability seal. Drainage, driven both by hydrostatic pressure and the body force on the draining fluid, leads to an initial rapid advance followed by a gradual retreat of the current to a steady-state. By incorporating a vertical array of these single layer models we are able to capture the rise of the buoyant plume in layered reservoirs. We find that the plume is characterized by a broad head with a tail given by the steady state extent.

  13. DSMC simulation of Io's unsteady Tvashtar plume

    Science.gov (United States)

    Hoey, W. A.; Ackley, P. C.; Trafton, L. M.; Goldstein, D. B.; Varghese, P. L.

    2016-11-01

    Jupiter's moon Io supports its rarefied atmosphere with prolific tidally-driven episodic volcanism. Its largest volcanic plumes erupt violently and exhibit intricate structure, their canopies rising to hundreds of km above the Ionian surface. In early 2007, the NASA New Horizons (NH) spacecraft captured the active Tvashtar plume in a time sequence of panchromatic images at high spatial resolution and observed both discrete "filamentary" patterns in the descending particulate structure, and a prominent traveling canopy wave. These are transient and asymmetric features, indicative of Tvashtar's unresolved and complex vent processes. In this work, we introduce a methodology for identifying vent spatial and temporal scales in the rarefied plume. Three-dimensional DSMC simulations of the collisional gas flowfield are combined with a flow-tracking dust particle model, enabling a broad exploration of parameter space in pursuit of the critical frequencies that qualitatively reproduce the dynamical phenomena observed in Tvashtar's collisional canopy and providing insight into the dynamics of transient extra-terrestrial volcanic plumes.

  14. Relative Abundance Measurements in Plumes and Interplumes

    CERN Document Server

    Guennou, Chloé; Savin, Daniel Wolf

    2015-01-01

    We present measurements of relative elemental abundances in plumes and interplumes. Plumes are bright, narrow structures in coronal holes that extend along open magnetic field lines far out into the corona. Previous work has found that in some coronal structures the abundances of elements with a low first ionization potential (FIP) 10 eV). We have used EIS spectroscopic observations made on 2007 March 13 and 14 over an ~24 hour period to characterize abundance variations in plumes and interplumes. To assess their elemental composition, we have used a differential emission measure (DEM) analysis, which accounts for the thermal structure of the observed plasma. We have used lines from ions of iron, silicon, and sulfur. From these we have estimated the ratio of the iron and silicon FIP bias relative to that for sulfur. From the results, we have created FIP-bias-ratio maps. We find that the FIP-bias ratio is sometimes higher in plumes than in interplumes and that this enhancement can be time dependent. These res...

  15. Plume or no Plume, the Case of the Siberian Trap Formation

    Science.gov (United States)

    Reichow, M. K.; Saunders, A. D.; White, R. V.; Al'Mukhamedov, A. I.; Medvedev, A. I.; Inger, S.

    2003-12-01

    The generation mechanism of continental large igneous provinces, such as the Siberian Traps, are matters of recent debate, particularly their relation to mantle plumes derived from the Earth's interior. Alternative models relate the formation of large igneous provinces to bolide impacts or small-scale convection at the boundary of asymmetric lithospheres. Neither of these models is without criticism and each model cannot explain all characteristics of continental flood basalt formation alone. However, strong support for the involvement of a mantle plume comes from the observation that large volumes of basaltic melts ( ˜3 x 106 km3) erupted within a short period of time (pulse of volcanism extruded over large areas of the Siberian craton. Although the major and trace element data are consistent with a plume origin for the Siberian Traps, they cannot prove it; however, magma volume and timing constraints do strongly suggest that a mantle plume was involved in the formation of the Earth's largest continental flood basalt province.

  16. Effects of facility backpressure on the performance and plume of a Hall thruster

    Science.gov (United States)

    Walker, Mitchell Louis Ronald

    2005-07-01

    this work aims to develop a fundamental understanding of how multi-kW clustered Hall thrusters operate and how to use single-engine ground-based data to predict the performance, plume interaction, and operation of a cluster. The results show that the plume and operating characteristics of the cluster are governed primarily by the facility backpressure and not the adjacent thruster. At nearly equal backpressure, the thrust is equal to the sum of the thrust of the monolithic thrusters at the lower anode flow rate. At the upper anode flow rate, the sum of the thrust of the monolithic thrusters under predicts the cluster thrust by 5%. This may be caused by each cluster element ingesting unionized propellant from the adjacent thruster. In addition, a cathode sharing investigation shows negligible change in the discharge current and cathode-to-ground voltage for thruster centerline separation distances up to 2 meters. A cathode displacement investigation shows that the Hall thruster starts reliably and performs nominally at cathode separation distances up to 1.1 meters. Collectively, the results of this work shed light on future facility designs that can reduce facility effects at pumping speeds that are not significantly above those of current facilities.

  17. Volcanic Plume Measurements with UAV (Invited)

    Science.gov (United States)

    Shinohara, H.; Kaneko, T.; Ohminato, T.

    2013-12-01

    Volatiles in magmas are the driving force of volcanic eruptions and quantification of volcanic gas flux and composition is important for the volcano monitoring. Recently we developed a portable gas sensor system (Multi-GAS) to quantify the volcanic gas composition by measuring volcanic plumes and obtained volcanic gas compositions of actively degassing volcanoes. As the Multi-GAS measures variation of volcanic gas component concentrations in the pumped air (volcanic plume), we need to bring the apparatus into the volcanic plume. Commonly the observer brings the apparatus to the summit crater by himself but such measurements are not possible under conditions of high risk of volcanic eruption or difficulty to approach the summit due to topography etc. In order to overcome these difficulties, volcanic plume measurements were performed by using manned and unmanned aerial vehicles. The volcanic plume measurements by manned aerial vehicles, however, are also not possible under high risk of eruption. The strict regulation against the modification of the aircraft, such as installing sampling pipes, also causes difficulty due to the high cost. Application of the UAVs for the volcanic plume measurements has a big advantage to avoid these problems. The Multi-GAS consists of IR-CO2 and H2O gas analyzer, SO2-H2O chemical sensors and H2 semiconductor sensor and the total weight ranges 3-6 kg including batteries. The necessary conditions of the UAV for the volcanic plumes measurements with the Multi-GAS are the payloads larger than 3 kg, maximum altitude larger than the plume height and installation of the sampling pipe without contamination of the exhaust gases, as the exhaust gases contain high concentrations of H2, SO2 and CO2. Up to now, three different types of UAVs were applied for the measurements; Kite-plane (Sky Remote) at Miyakejima operated by JMA, Unmanned airplane (Air Photo Service) at Shinomoedake, Kirishima volcano, and Unmanned helicopter (Yamaha) at Sakurajima

  18. Lidar measurements of launch vehicle exhaust plumes

    Science.gov (United States)

    Dao, Phan D.; Curtis, David; Farley, Robert; Soletsky, Philip; Davidson, Gilbert; Gelbwachs, Jerry A.

    1997-10-01

    The Mobile Lidar Trailer (MLT) was developed and operated to characterize launch vehicle exhaust plume and its effects on the environment. Two recent applications of this facility are discussed in this paper. In the first application, the MLT was used to characterize plumes in the stratosphere up to 45 km in support of the Air Force Space and Missile Center's Rocket Impact on Stratospheric Ozone program. Solid rocket motors used by Titan IV and other heavy launch vehicles release large quantities of gaseous hydrochloric acid in the exhaust and cause concerns about a possible depletion of the ozone layer. The MLT was deployed to Cape Canaveral Air Station since October 1995 to monitor ozone and to investigate plume dynamics and properties. Six campaigns have been conducted and more are planned to provide unique data with the objective of addressing the environmental issues. The plume was observed to disperse rapidly into horizontally extended yet surprisingly thin layer with thickness recorded in over 700 lidar profiles to be less than 250 meters. MLT operates with the laser wavelengths of 532, 355 and 308 nm and a scanning receiving telescope. Data on particle backscattering at the three wavelengths suggest a consistent growth of particle size in the 2-3 hour observation sessions following the launch. In the second type of application, the MLT was used as a remote sensor of nitrogen dioxide, a caustic gaseous by-product of common liquid propellant oxidizer. Two campaigns were conducted at the Sol Se Mete Canyon test site in New Mexico in December 1996 an January 1997 to study the dispersion of nitrogen dioxide and rocket plume.

  19. A comparison of the turbulent entrainment process in line plumes and wall plumes

    Science.gov (United States)

    Parker, David; Burridge, Henry; Partridge, Jamie; Linden, Paul

    2016-11-01

    Flows driven by sources of buoyancy appear in a large number of geophysical and industrial applications. The process of turbulent entrainment in these flows is key to understanding how they evolve and how one might model them. It has been observed that the entrainment is reduced when a line source of buoyancy is positioned immediately adjacent to a wall. To gain insight into the effect of the wall on the entrainment process we perform simultaneous PIV and LIF on both line plumes, in the absence of any boundary, and when the source is adjacent to a vertical boundary forming a wall plume. The experiments are designed to isolate the effect of the wall by using the same experimental setup and parameters for both flows with the addition of the wall and half the buoyancy flux used in the wall plume case. Of particular interest is the effect the large scale eddies, forming at the edge of the plume and engulfing ambient fluid, have on the entrainment process. By using velocity statistics in a coordinate system based on the instantaneous scalar edge of the plume, a technique we have recently used to analyse similar effects in an axisymmetric plume, the significance of this large scale engulfment will be quantified.

  20. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Vertes, Akos; Stolee, Jessica A.

    2016-06-07

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  1. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Science.gov (United States)

    Vertes, Akos; Stolee, Jessica A.

    2016-06-07

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  2. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Science.gov (United States)

    Vertes, Akos; Stolee, Jessica A.

    2014-09-09

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  3. Plume meander and dispersion in a stable boundary layer

    Science.gov (United States)

    Hiscox, April L.; Miller, David R.; Nappo, Carmen J.

    2010-11-01

    Continuous lidar measurements of elevated plume dispersion and corresponding micrometeorology data are analyzed to establish the relationship between plume behavior and nocturnal boundary layer dynamics. Contrasting nights of data from the JORNADA field campaign in the New Mexico desert are analyzed. The aerosol lidar measurements were used to separate the plume diffusion (plume spread) from plume meander (displacement). Mutiresolution decomposition was used to separate the turbulence scale (90 s). Durations of turbulent kinetic energy stationarity and the wind steadiness were used to characterize the local scale and submesoscale turbulence. Plume meander, driven by submesoscale wind motions, was responsible for most of the total horizontal plume dispersion in weak and variable winds and strong stability. This proportion was reduced in high winds (i.e., >4 m s-1), weakly stable conditions but remained the dominant dispersion mechanism. The remainder of the plume dispersion in all cases was accounted for by internal spread of the plume, which is a small eddy diffusion process driven by turbulence. Turbulence stationarity and the wind steadiness are demonstrated to be closely related to plume diffusion and plume meander, respectively.

  4. ASHEE: a compressible, Equilibrium–Eulerian model for volcanic ash plumes

    Directory of Open Access Journals (Sweden)

    M. Cerminara

    2015-10-01

    and Balachandar, 2001, valid for low concentration regimes (particle volume fraction less than 10−3 and particles Stokes number (St, i.e., the ratio between their relaxation time and flow characteristic time not exceeding about 0.2. The new model, which is called ASHEE (ASH Equilibrium Eulerian, is significantly faster than the N-phase Eulerian model while retaining the capability to describe gas-particle non-equilibrium effects. Direct numerical simulation accurately reproduce the dynamics of isotropic, compressible turbulence in subsonic regime. For gas-particle mixtures, it describes the main features of density fluctuations and the preferential concentration and clustering of particles by turbulence, thus verifying the model reliability and suitability for the numerical simulation of high-Reynolds number and high-temperature regimes in presence of a dispersed phase. On the other hand, Large-Eddy Numerical Simulations of forced plumes are able to reproduce their observed averaged and instantaneous flow properties. In particular, the self-similar Gaussian radial profile and the development of large-scale coherent structures are reproduced, including the rate of turbulent mixing and entrainment of atmospheric air. Application to the Large-Eddy Simulation of the injection of the eruptive mixture in a stratified atmosphere describes some of important features of turbulent volcanic plumes, including air entrainment, buoyancy reversal, and maximum plume height. For very fine particles (St → 0, when non-equilibrium effects are negligible the model reduces to the so-called dusty-gas model. However, coarse particles partially decouple from the gas phase within eddies (thus modifying the turbulent structure and preferentially concentrate at the eddy periphery, eventually being lost from the plume margins due to the concurrent effect of gravity. By these mechanisms, gas-particle non-equilibrium processes are able to influence the large-scale behavior of volcanic plumes.

  5. Numerous Bubble Plumes Mapped and New Seeps Characterized on the Cascadia Margin

    Science.gov (United States)

    Embley, R. W.; Merle, S. G.; Raineault, N.; Baumberger, T.; Seabrook, S.; Johnson, H. P.; Trehu, A. M.; Lupton, J. E.; Thurber, A. R.; Torres, M. E.; Hammond, S. R.; Solomon, E. A.; Salmi, M.

    2016-12-01

    A cruise on the E/V Nautilus (operated by the Ocean Exploration Trust Inc.) in June 2016 discovered more than 400 presumptive methane bubble plumes on the Cascadia continental margin (Washington, Oregon and northern California), the accretionary portion of the Cascadia subduction zone. The plumes occur in water depths from 125 to 1624 m and are associated with a wide range of geologic environments including continental shelf, canyon walls and floors, mid-slope accretionary ridges, and within a narrow band including the 500 m contour (the approximate upper limit of hydrate stability for this region). All but one of the sites were discovered using the E/V Nautilus' EM302 multibeam echo sounding system to detect bubble plumes in the water column. Nine of the bubble plume sites were characterized using the Hercules remotely operated vehicle deployed from the E/V Nautilus. All of these seep sites were associated with a ubiquitous authigenic carbonate substratum. Exposures of methane hydrate were found at two locations; the floor of Astoria canyon at 850 m and a mid-slope site at 1030 m. Seafloor methane bubble streams were located at all but one of the dive sites, with considerable variation in their behavior. At some sites there were only low-flow and ephemeral bubble streams, at other sites there was a high flux of steady-state bubble streams, and a few sites were characterized by periodic (seconds) bursts of large bubble clusters from subseafloor voids. Mid-water acoustic detection and quantification of methane bubble plumes is a much needed tool that should lead toward inventorying and monitoring methane fluxes between the solid earth and the ocean. The Cascadia cruise was especially productive because the E/V Nautilus' main mission is ocean exploration, which encouraged the science team to take full advantage of the tandem use of the sonar and ROV exploration capabilities.

  6. Observation and Simulation of Ion Flow Stagnation in the Enceladus Plume

    Science.gov (United States)

    Tokar, R. L.; Omidi, N.; Averkamp, T.; Wang, Z.; Gurnett, D. A.; Thomsen, M. F.; Crary, F. J.

    2010-12-01

    The Cassini Plasma Spectrometer (CAPS) detected freshly-produced water-group ions (O+, OH+, H2O+, H3O+) and heavier charged water clusters (HxO2)+ very close to Enceladus within and outside of the south polar plume, see (1). The data were obtained during close flybys of Enceladus in 2008 and 2009 (E3, E5, E7) when CAPS viewing of the ion plasma was favorable. The ions are observed in CAPS detectors looking in the Cassini ram direction and close to the ram kinetic energy, indicative of a nearly stagnant (at rest with respect to Enceladus) plasma flow in the plume. In this study these CAPS observations are compared with 3D hybrid simulations of the Enceladus interaction (2). The primary goal is to simulate the spatial extent of the ion flow stagnation in and near the plume observed by CAPS. The simulations include not only plume water vapor undergoing charge exchange with the ambient ion flow but also heavy plume dust that acquires a negative charge. The neutral dust spatial distribution is modeled using particle impact rates obtained from Radio and Plasma Wave System (RPWS) data while plasma fluid parameters during the encounters are obtained from CAPS. The dust is a second heavy particle component in the simulation that is followed in the same manner as the positive ions. The dust absorption of electrons mass-loads the plasma producing flow deceleration observable by CAPS over the high impact regions measured by RPWS. This deceleration is compared with that due to the charge exchange process. 1.)Tokar,R.L. et al. Geophys. Res. Lett., 36, L13203, doi:10.1029/2009GL038923, 2009. 2.)Omidi,N. et al., J. Geophys. Res., 115, A05212, doi:10.1029/2009JA014391, 2010.

  7. Cluster headache

    Science.gov (United States)

    Histamine headache; Headache - histamine; Migrainous neuralgia; Headache - cluster; Horton's headache; Vascular headache - cluster ... A cluster headache begins as a severe, sudden headache. The headache commonly strikes 2 to 3 hours after you fall ...

  8. Cluster Forests

    CERN Document Server

    Yan, Donghui; Jordan, Michael I

    2011-01-01

    Inspired by Random Forests (RF) in the context of classification, we propose a new clustering ensemble method---Cluster Forests (CF). Geometrically, CF randomly probes a high-dimensional data cloud to obtain "good local clusterings" and then aggregates via spectral clustering to obtain cluster assignments for the whole dataset. The search for good local clusterings is guided by a cluster quality measure $\\kappa$. CF progressively improves each local clustering in a fashion that resembles the tree growth in RF. Empirical studies on several real-world datasets under two different performance metrics show that CF compares favorably to its competitors. Theoretical analysis shows that the $\\kappa$ criterion is shown to grow each local clustering in a desirable way---it is "noise-resistant." A closed-form expression is obtained for the mis-clustering rate of spectral clustering under a perturbation model, which yields new insights into some aspects of spectral clustering.

  9. Star Clusters

    OpenAIRE

    Gieles, M.

    1993-01-01

    Star clusters are observed in almost every galaxy. In this thesis we address several fundamental problems concerning the formation, evolution and disruption of star clusters. From observations of (young) star clusters in the interacting galaxy M51, we found that clusters are formed in complexes of stars and star clusters. These complexes share similar properties with giant molecular clouds, from which they are formed. Many (70%) of the young clusters will not survive the fist 10 Myr, due to t...

  10. Time-series measurements of hydrothermal plume volume flux with imaging sonar

    Science.gov (United States)

    Xu, G.; Jackson, D. R.; Bemis, K. G.; Rona, P. A.

    2012-12-01

    COVIS (Cabled Observatory Vent Imaging Sonar) is an innovative sonar system designed to quantitatively monitor the outputs of deep-sea hydrothermal vent clusters for both high-temperature focused vents and diffuse flows. In September 2010, COVIS was connected to the NEPTUNE Canada underwater ocean observatory network (http://www.NEPTUNEcanada.ca) at the Grotto vent cluster at the Main Endeavour Field on the Endeavour Segment of the Juan de Fuca Ridge. Since then, COVIS has been monitoring the hydrothermal plumes above Grotto by transmitting high-frequency (400 kHz), pulsed acoustic waves towards the plumes and recording the backscattered signals from each pulse, except for a one-year hiatus due to the power-off of the NEPTUNE Canada network between November 2010 and September 2011. The received backscatter signals are transmitted via the NEPTUNE Canada network to the land-based servers in real time, where a combination of automatic and manual data analyses produces a plume volume-flux and flow-rate time series using both the intensity and Doppler shift of the backscatter signals. The initial 30-day time series (Sep-Oct 2010) was presented in AGU Fall meeting, 2011. Evident short-term temporal variations (Sensor (BARS, principal Investigator M. Lilley, University of Washington) and the Remotely Activated water Sampler (RAS, principal Investigator D. Butterfield, National Oceanic and Atmospheric Administration and University of Washington) at the vent orifices to link the variations observed in the buoyant plume with those at the orifices. This work is supported by NSF award OCE-0825088 to Rutgers.

  11. Flows in Sunspot Plumes Detected with SOHO

    CERN Document Server

    Brynildsen, N; Brekke, P; Fredvik, T; Haugan, S V H; Kjeldseth-Moe, O; Wikstøl, O

    1998-01-01

    Bright EUV sunspot plumes have been observed in eight out of eleven different sunspot regions with the Coronal Diagnostic Spectrometer -- CDS on SOHO. From wavelength shifts we derive the line-of-sight velocity, relative to the average velocity in the rastered area, 120 arcsec x 120 arcsec. In sunspot plumes we find that the motion is directed away from the observer and increases with increasing line formation temperature, reaches a maximum between 15 and 41 km~s$^{-1}$ close to log T $\\approx$ 5.5, then decreases abruptly. The flow field in the corona is not well correlated with the flow in the transition region and we discuss briefly the implication of this finding.

  12. Plume RF interference calculations for space shuttle

    Science.gov (United States)

    Boynton, F. P.; Rajasekhar, P. S.

    1978-01-01

    During a static ground test of a full-scale SRM, measurements of attenuation of the UHF 416.5 MHz Range Safety Signal, the VHF voice link (230 MHz), and of S-band (c. 2.2. GHz) communications links were undertaken. Analyses of these results indicate that measurable attenuation did occur at all test frequencies. The measured attenuation levels are compared with a simple model in which the received signal is identified as that diffracted about the edge of the highly absorbing plume and the signal level in the shadow zone is evaluated using the formula for diffraction at a straight edge. The comparison is satisfactory at VHF and UHF frequencies, and slightly less so at S-band. Reasons for the discrepancies found at higher frequencies are discussed. A revised procedure which appears to relieve the accuracy problem was developed. This procedure is discussed along with applications to high altitude SRM plume attenuation.

  13. Numerical Modelling of Jets and Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben

    1993-01-01

    An overview on numerical models for prediction of the flow and mixing processes in turbulent jets and plumes is given. The overview is structured to follow an increasing complexity in the physical and numerical principles. The various types of models are briefly mentioned, from the one-dimensiona......An overview on numerical models for prediction of the flow and mixing processes in turbulent jets and plumes is given. The overview is structured to follow an increasing complexity in the physical and numerical principles. The various types of models are briefly mentioned, from the one......-dimensional integral method to the general 3-dimensional solution of the Navier-Stokes equations. Also the predictive capabilities of the models are discussed. The presentation takes the perspective of civil engineering and covers issues like sewage outfalls and cooling water discharges to the sea....

  14. Electric Propulsion Plume Simulations Using Parallel Computer

    Directory of Open Access Journals (Sweden)

    Joseph Wang

    2007-01-01

    Full Text Available A parallel, three-dimensional electrostatic PIC code is developed for large-scale electric propulsion simulations using parallel supercomputers. This code uses a newly developed immersed-finite-element particle-in-cell (IFE-PIC algorithm designed to handle complex boundary conditions accurately while maintaining the computational speed of the standard PIC code. Domain decomposition is used in both field solve and particle push to divide the computation among processors. Two simulations studies are presented to demonstrate the capability of the code. The first is a full particle simulation of near-thruster plume using real ion to electron mass ratio. The second is a high-resolution simulation of multiple ion thruster plume interactions for a realistic spacecraft using a domain enclosing the entire solar array panel. Performance benchmarks show that the IFE-PIC achieves a high parallel efficiency of ≥ 90%

  15. Cruise Ship Plume Tracking Survey Report

    Science.gov (United States)

    2002-09-01

    The U. S. Environmental Protection Agency (EPA) is developing a Cruise Ship Discharge Assessment Report in response to a petition the agency received in March 2000. The petition requested that EPA assess and where necessary control discharges from cruise ships. Comments received during public hearings, in 2000, resulted in the EPA agreeing to conduct a survey to assess the discharge plumes resulting from cruise ships, operating in ocean waters off the Florida coast and to compare the results to the Alaska dispersion models. This survey report describes the daily activities of August 2001 Cruise Ship Plume Tracking Survey, and provides a synopsis of the observations from the survey. It also provides data that can be used to assess dispersion of cruise ship wastewater discharges, while in transit. A description of the survey methods is provided in Section 2. Survey results are presented in Section 3. Findings and conclusions are discussed in Section 4.

  16. Clustered impacts - Experiments and implications

    Science.gov (United States)

    Schultz, P. H.; Gault, D. E.

    1985-04-01

    The characteristics of impact by clusters of projectiles are experimentally studied by launching grouped projectiles of aluminum shot, steel shot, iron filings, and sand. Cratering efficiency is considered as a function of a dimensionless parameter related to projectile size and impact velocity. The effects of different target and projectile densities on cratering efficiency are examined. Crater morphology is addressed by considering a typical example, reviewing the systematics between cluster dispersion and crater morphology for vertical impacts, and examining oblique angle impacts which have relevance for planetary secondary cratering processes. These results are compared with impacts by single bodies with different strengths. The evolution of the ejecta plume for clustered impacts is compared to that for single-body impacts for vertical and oblique impacts from 1.3 to 1.8 km/s. The experimental results are discussed in the context of planetary surface processes, emphasizing processes in an atmosphere-free environment and secondary impact cratering.

  17. Sub-Grid Scale Plume Modeling

    Directory of Open Access Journals (Sweden)

    Greg Yarwood

    2011-08-01

    Full Text Available Multi-pollutant chemical transport models (CTMs are being routinely used to predict the impacts of emission controls on the concentrations and deposition of primary and secondary pollutants. While these models have a fairly comprehensive treatment of the governing atmospheric processes, they are unable to correctly represent processes that occur at very fine scales, such as the near-source transport and chemistry of emissions from elevated point sources, because of their relatively coarse horizontal resolution. Several different approaches have been used to address this limitation, such as using fine grids, adaptive grids, hybrid modeling, or an embedded sub-grid scale plume model, i.e., plume-in-grid (PinG modeling. In this paper, we first discuss the relative merits of these various approaches used to resolve sub-grid scale effects in grid models, and then focus on PinG modeling which has been very effective in addressing the problems listed above. We start with a history and review of PinG modeling from its initial applications for ozone modeling in the Urban Airshed Model (UAM in the early 1980s using a relatively simple plume model, to more sophisticated and state-of-the-science plume models, that include a full treatment of gas-phase, aerosol, and cloud chemistry, embedded in contemporary models such as CMAQ, CAMx, and WRF-Chem. We present examples of some typical results from PinG modeling for a variety of applications, discuss the implications of PinG on model predictions of source attribution, and discuss possible future developments and applications for PinG modeling.

  18. Comparison of the measured and modeled electron densities and temperatures in the ionosphere and plasmasphere during 14-16 May 1991

    Science.gov (United States)

    Pavlov, A. V.; Pavlova, N. M.

    2004-01-01

    The electron density and temperature in the ionosphere and plasmasphere measured by the Millstone Hill incoherent-scatter radar and the instruments on board of the EXOS-D satellite are compared with calculations from a time-dependent mathematical model of the Earth's ionosphere and plasmasphere during 14-16 May 1991. Use of [O]/[N2] correction factors with the NRLMSISE-00 model of the neutral atmosphere was found to bring the modeled and measured F-region main peak electron densities into agreement. It was found that the nighttime additional heating rate should be added to the normal photoelectron heating in the electron energy equation, in the nighttime plasmasphere region, in order for the model to reproduce the observed high plasmaspheric electron temperature within the Millstone Hill magnetic field flux tube in the Northern Hemisphere. The additional heating brings the measured and modeled electron temperatures into agreement in the plasmasphere and into a very large disagreement in the ionosphere, if the classical electron heat flux along magnetic field lines is used. An approach of Pavlov et al. (2000, 2001) based on a new effective electron thermal conductivity coefficient along the magnetic field line and the evaluated additional heating of electrons in the plasmasphere is used to explain the observed electron temperature in the ionosphere and plasmasphere. This approach leads to a heat flux which is less than that given by the classical theory. The effects of the additional plasmaspheric heating of electrons on the electron temperature and density are small at the F-region altitudes if the modified electron heat flux is used. We found that the resulting effect of vibrationally excited N2 and O2 on NmF2 is the decrease of the calculated NmF2 by up to a factor of about 2.7 by day and up to a factor of about 2.5 by night. The modeled electron temperature is very sensitive to the electron density, and this decrease in electron density results in an increase of

  19. Plume Comparisons between Segmented Channel Hall Thrusters

    Science.gov (United States)

    Niemack, Michael; Staack, David; Raitses, Yevgeny; Fisch, Nathaniel

    2001-10-01

    Angular ion flux plume measurements were taken in several configurations of segmented channel Hall thrusters. The configurations differed by the placement of relatively short rings made from materials with different conductive and secondary electron emission properties along the boron nitride ceramic channel of the thrusters (these have been shown to affect the plume [1]). The ion fluxes are compared with ion trajectory simulations based on plasma potential data acquired with a high speed emissive probe [2]. Preliminary results indicate that in addition to the physical properties of the segments, the plume angle can be strongly affected by the placement of segmented rings relative to the external and internal walls of the channel. [1] Y. Raitses, L. Dorf, A. Litvak and N. J. Fisch, Journal of Applied Physics 88, 1263, 2000 [2] D. Staack, Y. Raitses, N. J. Fisch, Parametric Investigations of Langmuir Probe Induced Perturbations in a Hall Thruster, DPP01 Poster Presentation This work was supported by the U.S. DOE Contract No. DE-ACO2-76-CHO3073.

  20. Monitoring and forecasting Etna volcanic plumes

    Directory of Open Access Journals (Sweden)

    S. Scollo

    2009-09-01

    Full Text Available In this paper we describe the results of a project ongoing at the Istituto Nazionale di Geofisica e Vulcanologia (INGV. The objective is to develop and implement a system for monitoring and forecasting volcanic plumes of Etna. Monitoring is based at present by multispectral infrared measurements from the Spin Enhanced Visible and Infrared Imager on board the Meteosat Second Generation geosynchronous satellite, visual and thermal cameras, and three radar disdrometers able to detect ash dispersal and fallout. Forecasting is performed by using automatic procedures for: i downloading weather forecast data from meteorological mesoscale models; ii running models of tephra dispersal, iii plotting hazard maps of volcanic ash dispersal and deposition for certain scenarios and, iv publishing the results on a web-site dedicated to the Italian Civil Protection. Simulations are based on eruptive scenarios obtained by analysing field data collected after the end of recent Etna eruptions. Forecasting is, hence, supported by plume observations carried out by the monitoring system. The system was tested on some explosive events occurred during 2006 and 2007 successfully. The potentiality use of monitoring and forecasting Etna volcanic plumes, in a way to prevent threats to aviation from volcanic ash, is finally discussed.

  1. Evidence for Little Shallow Entrainment in Starting Mantle Plumes

    Science.gov (United States)

    Lohmann, F. C.; Phipps Morgan, J.; Hort, M.

    2005-12-01

    Basalts from intraplate or hotspot ocean islands show distinct geochemical signatures. Their diversity in composition is generally believed to result from the upwelling plume entraining shallow mantle material during ascent, while potentially also entraining other deep regions of the mantle. Here we present results from analogue laboratory experiments and numerical modelling that there is evidence for little shallow entrainment into ascending mantle plumes, i.e. most of the plume signature is inherited from the source. We conducted laboratory experiments using glucose syrup contaminated with glass beads to visualize fluid flow and origin. The plume is initiated by heating from below or by injecting hot, uncontaminated syrup. Particle movement is captured by a CCD camera. In our numerical experiments we solve the Stokes equations for a viscous fluid at infinite Prandtl number with passive tracer particles being used to track fluid flow and entrainment rates, simulating laboratory as well as mantle conditions. In both analogue experiments and numerical models we observe the classical plume structure being embedded in a `sheath' of material from the plume source region that retains little of the original temperature anomaly of the plume source. Yet, this sheath ascends in the `slipstream' of the plume at speeds close to the ascent speed of the plume head, and effectively prevents the entrainment of surrounding material into the plume head or plume tail. We find that the source region is most effectively sampled by an ascending plume and that compositional variations in the source region are preserved during plume ascent. The plume center and plume sheath combined are composed of up to 85% source material. However, there is also evidence of significant entrainment of up to 30% of surrounding material into the outer layers of the plume sheath. Entrainment rates are found to be influenced by mantle composition and structure, with the radial viscosity profile of the

  2. Lunar maria - result of mantle plume activity?

    Science.gov (United States)

    Sharkov, E.

    It is generally accepted that lunar maria are the result of catastrophic impact events. However, comparative studying of the Earth's and the Moon's tectonomagmatic evolution could evidence about another way of these specific structures origin. Such studies showed that the both planetary bodies evolved on the close scenario: their geological development began after solidification of global magmatic oceans which led to appearance of their primordial crusts: granitic on the Earth and anorthositic - on the Moon. The further evolution of the both bodies occurred in two stages. For their first stages, lasted ˜2.5 mlrd. years on the Earth and ˜1.5 mlrd. years on the Moon, were typical melts, generated in depleted mantle (Bogatikov et al., 2000). However, at the boundary 2.2-2.0 Ga ago on the Earth and 3.9-3.8 Ga on the Moon another type of magmas appeared: geochemical enriched Fe-Ti picrites and basalts, characteristic for the terrestrial Phanerozoic plume-related situations, and basaltic mare magmatism with high-Ti varieties on the Moon. It suggests that evolution of the Earth's magmatism was linked with ascending of mantle plumes (superplumes) of two generation: (1) generated in the mantle, depleted during solidification of magmatic ocean and Archean magmatic activity, and (2) generated at the core-mantle boundary (CMB). The latter were enriched in the mantle fluid components (Fe, Ti, alkalies, etc); this lighter material could ascend to shallower depths, leading to change of tectonic processes, in particular, to appearance of plate tectonics as the major type of tectonomagmatic activity till now (Bogatikov et al., 2000). By analogy to the Earth, magmatism of the Moon was also linked with ascending of mantle plumes: (1) generated in the depleted mantle (magnesian suite) and (2) generated at the lunar CMB with liquid at that time metallic core (mare basalt and picrites with high-Ti varieties). Like on the Earth, these plumes were lighter than the older plumes, and

  3. Aerosol Plume Detection Algorithm Based on Image Segmentation of Scanning Atmospheric Lidar Data

    Energy Technology Data Exchange (ETDEWEB)

    Weekley, R. Andrew; Goodrich, R. Kent; Cornman, Larry B.

    2016-04-01

    An image-processing algorithm has been developed to identify aerosol plumes in scanning lidar backscatter data. The images in this case consist of lidar data in a polar coordinate system. Each full lidar scan is taken as a fixed image in time, and sequences of such scans are considered functions of time. The data are analyzed in both the original backscatter polar coordinate system and a lagged coordinate system. The lagged coordinate system is a scatterplot of two datasets, such as subregions taken from the same lidar scan (spatial delay), or two sequential scans in time (time delay). The lagged coordinate system processing allows for finding and classifying clusters of data. The classification step is important in determining which clusters are valid aerosol plumes and which are from artifacts such as noise, hard targets, or background fields. These cluster classification techniques have skill since both local and global properties are used. Furthermore, more information is available since both the original data and the lag data are used. Performance statistics are presented for a limited set of data processed by the algorithm, where results from the algorithm were compared to subjective truth data identified by a human.

  4. Weighted Clustering

    DEFF Research Database (Denmark)

    Ackerman, Margareta; Ben-David, Shai; Branzei, Simina

    2012-01-01

    We investigate a natural generalization of the classical clustering problem, considering clustering tasks in which different instances may have different weights.We conduct the first extensive theoretical analysis on the influence of weighted data on standard clustering algorithms in both...... the partitional and hierarchical settings, characterizing the conditions under which algorithms react to weights. Extending a recent framework for clustering algorithm selection, we propose intuitive properties that would allow users to choose between clustering algorithms in the weighted setting and classify...

  5. Experimental study of oil plume stability: Parametric dependences and optimization.

    Science.gov (United States)

    Li, Haoshuai; Shen, Tiantian; Bao, Mutai

    2016-10-15

    Oil plume is known to interact with density layer in spilled oil. Previous studies mainly focused on tracking oil plumes and predicting their impact on marine environment. Here, simulated experiments are presented that investigated the conditions inducing the formation of oil plume, focusing especially on the effects of oil/water volume ratio, oil/dispersant volume rate, ambient stratification and optimal conditions of oil plume on determining whether a plume will trap or escape. Scenario simulations showed that OWR influences the residence time most, dispersants dosage comes second and salinity least. The optimum residence time starts from 2387s, occurred at approximately condition (OWR, 0.1, DOR, 25.53% and salinity, 32.38). No change in the relative distribution under the more scale tank was observed, indicating these provide the time evolution of the oil plumes.

  6. Life Cycle of Mantle Plumes: A perspective from the Galapagos Plume (Invited)

    Science.gov (United States)

    Gazel, E.; Herzberg, C. T.

    2009-12-01

    Hotspots are localized sources of heat and magmatism considered as modern-day evidence of mantle plumes. Some hotspots are related to massive magmatic production that generated Large Igneous Provinces (LIPS), an initial-peak phase of plume activity with a mantle source hotter and more magmatically productive than present-day hotspots. Geological mapping and geochronological studies have shown much lower eruption rates for OIB compared to lavas from Large Igneous Provinces LIPS such as oceanic plateaus and continental flood provinces. Our study is the first quantitative petrological comparison of mantle source temperatures and extent of melting for OIB and LIP sources. The wide range of primary magma compositions and inferred mantle potential temperatures for each LIP and OIB occurrence suggest that this rocks originated form a hotspot, a spatially localized source of heat and magmatism restricted in time. Extensive outcrops of basalt, picrite, and sometimes komatiite with circa 65-95 Ma ages occupy portions of the pacific shore of Central and South America included in the Caribbean Large Igneous Province (CLIP). There is general consensus of a Pacific-origin of CLIP and most studies suggest that it was produced by melting in the Galapagos mantle plume. The Galapagos connection is consistent with isotopic and geochemical similarities with lavas from the present-day Galapagos hotspot. A Galapagos link for rocks in South American oceanic complexes (eg. the island of Gorgona) is more controversial and requires future work. The MgO and FeO contents of lavas from the Galapagos related lavas and their primary magmas have decreased since the Cretaceous. From petrological modeling we infer that these changes reflect a cooling of the Galapagos mantle plume from a potential temperature of 1560-1620 C in the Cretaceous to 1500 C at the present time. These temperatures are higher than 1350 C for ambient mantle associated with oceanic ridges, and provide support for the mantle

  7. Plume tectonics and cratons formation in the early Earth

    Science.gov (United States)

    Gerya, T.; Stern, R. J.; Baes, M.; Fischer, R.; Sizova, E.; Sobolev, S. V.; Whattam, S. A.

    2015-12-01

    Modern geodynamics and continental growth are critically driven by subduction and plate tectonics, however how this tectonic regime started and what geodynamic regime was before remains controversial. Most present-day subduction initiation mechanisms require acting plate forces and/or pre-existing zones of lithospheric weakness, which are themselves the consequence of plate tectonics. Here, we focus on plume-lithosphere interactions and spontaneous plume-induced subduction initiation, which does not require pre-existing lithospheric fabric and is viable for both stagnant lid and mobile/deformable lid conditions. We present results of 2D and 3D numerical modeling of plume-induced deformation and associated crustal growth resulting from tectono-magmatic interaction of ascending mantle plumes with oceanic-type lithosphere. We demonstrate that weakening of the lithosphere by plume-induced magmatism is the key factor allowing for its internal deformation and differentiation resulting in continental crust growth. We also show that plume-lithosphere interaction can enable subduction and rudimentary plate tectonics initiation at the margins of a crustal plateau growing above the plume head. We argue that frequent plume-arc interactions recorded in Archean crust could reflect either short-term plume-induced subduction or plume-induced episodic lithospheric drips. We furthermore suggest a distinct plume-tectonics regime operated on Earth before plate tectonics, which was associated with widespread tectono-magmatic heat and mass exchange between the crust and the mantle. This regime was characterized by weak deformable plates with low topography, massive juvenile crust production from mantle derived melts, mantle-flows-driven crustal deformation, magma-assisted crustal convection and widespread development of lithospheric delamination and crustal drips. Plume tectonics also resulted in growth of hot depleted chemically buoyant subcrustal proto-cratonic mantle layer. Later

  8. New method in computer simulations of electron and ion densities and temperatures in the plasmasphere and low-latitude ionosphere

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    Full Text Available A new theoretical model of the Earth’s low- and mid-latitude ionosphere and plasmasphere has been developed. The new model uses a new method in ionospheric and plasmaspheric simulations which is a combination of the Eulerian and Lagrangian approaches in model simulations. The electron and ion continuity and energy equations are solved in a Lagrangian frame of reference which moves with an individual parcel of plasma with the local plasma drift velocity perpendicular to the magnetic and electric fields. As a result, only the time-dependent, one-dimension electron and ion continuity and energy equations are solved in this Lagrangian frame of reference. The new method makes use of an Eulerian computational grid which is fixed in space co-ordinates and chooses the set of the plasma parcels at every time step, so that all the plasma parcels arrive at points which are located between grid lines of the regularly spaced Eulerian computational grid at the next time step. The solution values of electron and ion densities Ne and Ni and temperatures Te and Ti at the Eulerian computational grid are obtained by interpolation. Equations which determine the trajectory of the ionospheric plasma perpendicular to magnetic field lines and take into account that magnetic field lines are "frozen" in the ionospheric plasma are derived and included in the new model. We have presented a comparison between the modeled NmF2 and hmF2 and NmF2 and hmF2 which were observed at the anomaly crest and close to the geomagnetic equator simultaneously by the Huancayo, Chiclayo, Talara, Bogota, Panama, and Puerto Rico ionospheric sounders during the 7 October 1957 geomagnetically quiet time period at solar maximum. The model calculations show that there is a need to revise the model local time dependence of the equatorial upward E × B drift velocity given by Scherliess and Fejer (1999 at solar maximum during quiet

  9. Marine bird aggregations associated with the tidally-driven plume and plume fronts of the Columbia River

    Science.gov (United States)

    Zamon, Jeannette E.; Phillips, Elizabeth M.; Guy, Troy J.

    2014-09-01

    Freshwater discharge from large rivers into the coastal ocean creates tidally-driven frontal systems known to enhance mixing, primary production, and secondary production. Many authors suggest that tidal plume fronts increase energy flow to fish-eating predators by attracting planktivorous fishes to feed on plankton aggregated by the fronts. However, few studies of plume fronts directly examine piscivorous predator response to plume fronts. Our work examined densities of piscivorous seabirds relative to the plume region and plume fronts of the Columbia River, USA. Common murres (Uria aalge) and sooty shearwaters (Puffinus griseus) composed 83% of all birds detected on mesoscale surveys of the Washington and Oregon coasts (June 2003-2006), and 91.3% of all birds detected on fine scale surveys of the plume region less than 40 km from the river mouth (May 2003 and 2006). Mesoscale comparisons showed consistently more predators in the central plume area compared to the surrounding marine area (murres: 10.1-21.5 vs. 3.4-8.2 birds km-2; shearwaters: 24.2-75.1 vs. 11.8-25.9 birds km-2). Fine scale comparisons showed that murre density in 2003 and shearwater density in both 2003 and 2006 were significantly elevated in the tidal plume region composed of the most recently discharged river water. Murres tended to be more abundant on the north face of the plume. In May 2003, more murres and shearwaters were found within 3 km of the front on any given transect, although maximum bird density was not necessarily found in the same location as the front itself. Predator density on a given transect was not correlated with frontal strength in either year. The high bird densities we observed associated with the tidal plume demonstrate that the turbid Columbia River plume does not necessarily provide fish with refuge from visual predators. Bird predation in the plume region may therefore impact early marine survival of Pacific salmon (Oncorhynchus spp.), which must migrate through the

  10. Algorithms and analysis for underwater vehicle plume tracing.

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, Raymond Harry; Savage, Elizabeth L. (Texas A& M University, College Station, TX); Hurtado, John Edward (Texas A& M University, College Station, TX); Eskridge, Steven E.

    2003-07-01

    The goal of this research was to develop and demonstrate cooperative 3-D plume tracing algorithms for miniature autonomous underwater vehicles. Applications for this technology include Lost Asset and Survivor Location Systems (L-SALS) and Ship-in-Port Patrol and Protection (SP3). This research was a joint effort that included Nekton Research, LLC, Sandia National Laboratories, and Texas A&M University. Nekton Research developed the miniature autonomous underwater vehicles while Sandia and Texas A&M developed the 3-D plume tracing algorithms. This report describes the plume tracing algorithm and presents test results from successful underwater testing with pseudo-plume sources.

  11. An infrared method for plume rise visualization and measurement

    Science.gov (United States)

    Rickel, Cindy; Lamb, Brian; Guenther, Alex; Allwine, Eugene

    An infrared video camera and recording system were used to record near source plume rise from a low turbine stack at an oil gathering center at Prudhoe Bay, AK. The system provided real-time, continuous visualization of the plume using a color monitor while the images were recorded with a standard video tape recorder. Following the field study, single frame images were digitized using a micro-computer video system. As part of the digitization, the plume centerline was determined as well as an isotherm of the plume outline. In this application, one frame from each 2-min period in the record was digitized. The results were used to calculate the variability in plume centerline during each hour. During strong winds with blowing snow, the mean plume rise for the hour at 15 m downwind was 6±2 m. The observed plume rise from the turbine stack was greater than that calculated using momentum-only or buoyancy-only plume rise models and only slightly larger than that estimated from combined momentum-buoyancy plume rise models.

  12. Field experimental observations of highly graded sediment plumes

    DEFF Research Database (Denmark)

    Hjelmager Jensen, Jacob; Saremi, Sina; Jimenez, Carlos;

    2015-01-01

    A field experiment in the waters off the south-eastern coast of Cyprus was carried out to study near-field formation of sediment plumes from dumping. Different loads of sediment were poured into calm and limpid waters one at the time from just above the sea surface. The associated plumes, gravita......A field experiment in the waters off the south-eastern coast of Cyprus was carried out to study near-field formation of sediment plumes from dumping. Different loads of sediment were poured into calm and limpid waters one at the time from just above the sea surface. The associated plumes...

  13. Turbulence and Mixing in the Columbia River Plume

    Science.gov (United States)

    Kilcher, L. F.; Nash, J.; Moum, J.

    2004-12-01

    Thin bouyant plumes represent a technical challenge for in-situ observations. In July 2004 a unique set of measurements were taken in which our vertical microstructure profiler, Chameleon, and acoustics (300 kHz ADCP and 120 kHz echosounder) were modified to measure the O(1-5 m) thick plume. The Chameleon profiles included measurements of density, fluorescence, optical backscatter and turbulent energy dissipation. Intense turbulence was observed in plume fronts (with 30 m vertical displacements), at the plume base (with O(1 s-1) shear) and in O(20 m) thick bottom boundary layers. Preliminary results from 10 days of observations will be presented and discussed.

  14. Numerical investigation of two interacting parallel thruster-plumes and comparison to experiment

    Science.gov (United States)

    Grabe, Martin; Holz, André; Ziegenhagen, Stefan; Hannemann, Klaus

    2014-12-01

    Clusters of orbital thrusters are an attractive option to achieve graduated thrust levels and increased redundancy with available hardware, but the heavily under-expanded plumes of chemical attitude control thrusters placed in close proximity will interact, leading to a local amplification of downstream fluxes and of back-flow onto the spacecraft. The interaction of two similar, parallel, axi-symmetric cold-gas model thrusters has recently been studied in the DLR High-Vacuum Plume Test Facility STG under space-like vacuum conditions, employing a Patterson-type impact pressure probe with slot orifice. We reproduce a selection of these experiments numerically, and emphasise that a comparison of numerical results to the measured data is not straight-forward. The signal of the probe used in the experiments must be interpreted according to the degree of rarefaction and local flow Mach number, and both vary dramatically thoughout the flow-field. We present a procedure to reconstruct the probe signal by post-processing the numerically obtained flow-field data and show that agreement to the experimental results is then improved. Features of the investigated cold-gas thruster plume interaction are discussed on the basis of the numerical results.

  15. Flows in Sunspot Plumes Detected with SOHO

    Science.gov (United States)

    Brynildsen, N.; Maltby, P.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Wikstol, O.

    1998-09-01

    In the Letter, ``Flows in Sunspot Plumes Detected with the Solar and Heliospheric Observatory'' by N. Brynildsen, P. Maltby, P. Brekke, T. Fredvik, S. V. H. Haugan, O. Kjeldseth-Moe, and Ø. Wikstøl (ApJ, 502, L85 [1998]), the following correction should be made: In the last line on page L86, which reads ``peak line intensity I>=5 are located (1) above the umbra or, '' an ``Ī'' should be inserted so that the revised line reads ``peak line intensity I>=5Ī are located (1) above the umbra or.''

  16. Channelization of plumes beneath ice shelves

    KAUST Repository

    Dallaston, M. C.

    2015-11-11

    © 2015 Cambridge University Press. We study a simplified model of ice-ocean interaction beneath a floating ice shelf, and investigate the possibility for channels to form in the ice shelf base due to spatial variations in conditions at the grounding line. The model combines an extensional thin-film description of viscous ice flow in the shelf, with melting at its base driven by a turbulent ocean plume. Small transverse perturbations to the one-dimensional steady state are considered, driven either by ice thickness or subglacial discharge variations across the grounding line. Either forcing leads to the growth of channels downstream, with melting driven by locally enhanced ocean velocities, and thus heat transfer. Narrow channels are smoothed out due to turbulent mixing in the ocean plume, leading to a preferred wavelength for channel growth. In the absence of perturbations at the grounding line, linear stability analysis suggests that the one-dimensional state is stable to initial perturbations, chiefly due to the background ice advection.

  17. Intercontinental transport of nitrogen oxide pollution plumes

    Directory of Open Access Journals (Sweden)

    M. Wenig

    2003-01-01

    Full Text Available We describe the first satellite observation of intercontinental transport of nitrogen oxides emitted by power plants, verified by simulations with a particle tracer model. The analysis of such episodes shows that anthropogenic NOx plumes may influence the atmospheric chemistry thousands of kilometers away from its origin, as well as the ocean they traverse due to nitrogen fertilization. This kind of monitoring became possible by applying an improved algorithm to extract the tropospheric fraction of NO2 from the spectral data coming from the GOME instrument. As an example we show the observation of NO2 in the time period 4--14 May, 1998, from the South African Plateau to Australia which was possible due to favourable weather conditions during that time period which availed the satellite measurement. This episode was also simulated with the Lagrangian particle dispersion model FLEXPART which uses NOx emissions taken from an inventory for industrial emissions in South Africa and is driven with analyses from the European Centre for Medium-Range Weather Forecasts. Additionally lightning emissions were taken into account by utilizing Lightning Imaging Sensor data. Lightning was found to contribute probably not more than 25% of the resulting concentrations. Both, the measured and simulated emission plume show matching patterns while traversing the Indian Ocean to Australia and show great resemblance to the aerosol and CO2 transport observed by Piketh et al. (2000.

  18. GEOS 1 observations of low-energy ions in the earth's plasmasphere - A study on composition, and temperature and density structure under quiet geomagnetic conditions

    Science.gov (United States)

    Farrugia, C. J.; Geiss, J.; Balsiger, H.; Young, D. T.

    Data are presented on the composition and the temperature (T) and density (N) distributions of the earth's plasmasphere ionic population, obtained from GEOS 1 thermal-ion data. In deriving the N and T of the ions, a novel technique was employed, which is based on the modulation of the count rates by the spacecraft's spin. It was found that, for the major ion species H(+) and He(+), the relative density abundance He(+)/H(+) value of several percent was fairly common; the H(+) and He(+) ions are generally in thermal equilibrium, with temperatures varying between 4000 and 15,000 K, with a tendency to increase with L value. A comparison of the thermal structure obtained with those obtained by the Plasma Composition Experiment on ISEE and the Retarding Ion Mass Spectrometer on DE 1 showed no systematic difference between the 'energy' techniques used in these studies and the present 'angular' technique.

  19. Large-Amplitude Transmitter-Associated and Lightning-Associated Whistler Waves in the Earth's Inner Plasmasphere at L less than 2

    Science.gov (United States)

    Breneman, A.; Cattell, C.; Wygant, J.; Kersten, K.; Wilson, L. B., III; Schreiner, S.; Kellogg, P. J.; Goetz, K.

    2011-01-01

    We report observations of very large amplitude whistler mode waves in the Earth fs nightside inner radiation belt enabled by the STEREO Time Domain Sampler. Amplitudes range from 30.110 mV/m (zero ]peak), 2 to 3 orders of magnitude larger than previously observed in this region. Measurements from the peak electric field detector (TDSMax) indicate that these large ]amplitude waves are prevalent throughout the plasmasphere. A detailed examination of high time resolution electric field waveforms is undertaken on a subset of these whistlers at L 100 keV) electrons on a time scale of <1 s and thus may be an important previously unaccounted for source of energization or pitch ]angle scattering in the inner radiation belt.

  20. Meaningful Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Sanfilippo, Antonio P.; Calapristi, Augustin J.; Crow, Vernon L.; Hetzler, Elizabeth G.; Turner, Alan E.

    2004-05-26

    We present an approach to the disambiguation of cluster labels that capitalizes on the notion of semantic similarity to assign WordNet senses to cluster labels. The approach provides interesting insights on how document clustering can provide the basis for developing a novel approach to word sense disambiguation.

  1. Converging Supergranular Flows and the Formation of Coronal Plumes

    Science.gov (United States)

    Wang, Y.-M.; Warren, H. P.; Muglach, K.

    2016-01-01

    Earlier studies have suggested that coronal plumes are energized by magnetic reconnection between unipolar flux concentrations and nearby bipoles, even though magnetograms sometimes show very little minority-polarity flux near the footpoints of plumes. Here we use high-resolution extreme-ultraviolet (EUV) images and magnetograms from the Solar Dynamics Observatory (SDO) to clarify the relationship between plume emission and the underlying photospheric field. We find that plumes form where unipolar network elements inside coronal holes converge to form dense clumps, and fade as the clumps disperse again. The converging flows also carry internetwork fields of both polarities. Although the minority-polarity flux is sometimes barely visible in the magnetograms, the corresponding EUV images almost invariably show loop-like features in the core of the plumes, with the fine structure changing on timescales of minutes or less. We conclude that the SDO observations are consistent with a model in which plume emission originates from interchange reconnection in converging flows, with the plume lifetime being determined by the approximately 1-day evolutionary timescale of the supergranular network. Furthermore, the presence of large EUV bright points and/or ephemeral regions is not a necessary precondition for the formation of plumes, which can be energized even by the weak, mixed-polarity internetwork fields swept up by converging flows.

  2. Ocean outfall plume characterization using an Autonomous Underwater Vehicle.

    Science.gov (United States)

    Rogowski, Peter; Terrill, Eric; Otero, Mark; Hazard, Lisa; Middleton, William

    2013-01-01

    A monitoring mission to map and characterize the Point Loma Ocean Outfall (PLOO) wastewater plume using an Autonomous Underwater Vehicle (AUV) was performed on 3 March 2011. The mobility of an AUV provides a significant advantage in surveying discharge plumes over traditional cast-based methods, and when combined with optical and oceanographic sensors, provides a capability for both detecting plumes and assessing their mixing in the near and far-fields. Unique to this study is the measurement of Colored Dissolved Organic Matter (CDOM) in the discharge plume and its application for quantitative estimates of the plume's dilution. AUV mission planning methodologies for discharge plume sampling, plume characterization using onboard optical sensors, and comparison of observational data to model results are presented. The results suggest that even under variable oceanic conditions, properly planned missions for AUVs equipped with an optical CDOM sensor in addition to traditional oceanographic sensors, can accurately characterize and track ocean outfall plumes at higher resolutions than cast-based techniques.

  3. Identification of mantle plumes in the Emeishan Large Igneous Province

    Institute of Scientific and Technical Information of China (English)

    Yi-Gang Xu; Jifeng Xu; Yue-Jun Wang; Bin He; Xiaolong Huang; Zhenyu Luo; Sun-Lin Chung; Long Xiao; Dan Zhu; Hui Shao; Wei-Ming Fan

    2007-01-01

    @@ The plume hypothesis has been recently challengedlargely because some fundamental aspects predicted bythe modeling of plumes are found to be lacking in someclassic hotspot regions. This review paper summarizesrecent achievements made in the late Permian Emeishan continental flood basalt province in southwest China.

  4. CONVERGING SUPERGRANULAR FLOWS AND THE FORMATION OF CORONAL PLUMES

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.-M.; Warren, H. P. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Muglach, K., E-mail: yi.wang@nrl.navy.mil, E-mail: harry.warren@nrl.navy.mil, E-mail: karin.muglach@nasa.gov [Code 674, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2016-02-20

    Earlier studies have suggested that coronal plumes are energized by magnetic reconnection between unipolar flux concentrations and nearby bipoles, even though magnetograms sometimes show very little minority-polarity flux near the footpoints of plumes. Here we use high-resolution extreme-ultraviolet (EUV) images and magnetograms from the Solar Dynamics Observatory (SDO) to clarify the relationship between plume emission and the underlying photospheric field. We find that plumes form where unipolar network elements inside coronal holes converge to form dense clumps, and fade as the clumps disperse again. The converging flows also carry internetwork fields of both polarities. Although the minority-polarity flux is sometimes barely visible in the magnetograms, the corresponding EUV images almost invariably show loop-like features in the core of the plumes, with the fine structure changing on timescales of minutes or less. We conclude that the SDO observations are consistent with a model in which plume emission originates from interchange reconnection in converging flows, with the plume lifetime being determined by the ∼1 day evolutionary timescale of the supergranular network. Furthermore, the presence of large EUV bright points and/or ephemeral regions is not a necessary precondition for the formation of plumes, which can be energized even by the weak, mixed-polarity internetwork fields swept up by converging flows.

  5. Effects of ambient turbulence on a particle plume

    Science.gov (United States)

    Lai, Adrian C. H.; Er, J. W.; Law, Adrian W. K.; Adams, E. Eric

    2015-11-01

    We investigated experimentally the effects of ambient turbulence on a particle plume. Homogeneous and isotropic turbulent ambient water was generated by a random jet array in a glass tank. Glass beads of different particle diameters were released continuously into this turbulent ambient using a submerged hourglass, forming particle plumes with a constant efflux velocity; different initial velocities were tested for each particle size. We focused on the region in which the integral length scale of the ambient eddies is larger than that of the particle plume size. Following the arguments of Hunt (1994) and the observation of Hubner (2004) on a single-phase plume, it is expected that in this region, the internal structure or Lagrangian spreading of the particle plume, will not be significantly affected, but the plume centerline would meander due to the ambient turbulence leading to an increase in the Eulerian width. In the presentation, first, we will present our preliminary experimental data which showed that this is also true for two-phase particle plumes. Second, based on this observation, we developed a theoretical framework using a stochastic approach to predict the spreading of the plume. Predictions of the model will be compared with our experimental data. This research was supported by the National Research Foundation Singapore through the Singapore MIT Alliance for Research and Technology's Center for Environmental Sensing and Modeling interdisciplinary research program.

  6. The Structure of Enceladus' Plume from Cassini Occultation Observations

    Science.gov (United States)

    Hansen, C. J.; Esposito, L. W.; Buffington, B. B.; Colwell, J.; Hendrix, A. R.; Meinke, B. K.; Shemansky, D. E.; Stewart, I.; West, R. A.

    2011-12-01

    Cassini's Ultraviolet Imaging Spectrograph (UVIS) has observed 2 stellar and one solar occultation by Enceladus' water vapor plume. These observations have established that water is the primary constituent of the plume, allowed us to calculate the flux of water coming from the plume, and detected super-sonic jets of gas imbedded within the plume [1]. On 19 October 2011 two stars (epsilon and zeta Orionis) will simultaneously be occulted by the plume, and the signal of the two will be in separate pixels on the detector. This is a tangential occultation that will provide a horizontal cut through the plume at two altitudes. The two stars are separated by 24 mrad, or ~20 km, with the lower altitude star 18 km above the limb at its closest point. The groundtrack is similar to the 2010 solar occultation, but viewed from the other side of the plume. Results from this new data set with implications for the vertical structure of the plume and jets will be presented.

  7. Laboratory-Scale Simulation of Spiral Plumes in the Mantle

    CERN Document Server

    Sharifulin, A N

    2012-01-01

    On the basis of laboratory simulation a mechanism is established for the formation of the upper mantle convection spiral plumes from a hot point in the presence of a roll-type large-scale convective flow. The observed plume has horizontal sections near the upper limit, which may lead to the formation of chains of volcanic islands.

  8. Determining resolvability of mantle plumes with synthetic seismic modeling

    Science.gov (United States)

    Maguire, R.; Van Keken, P. E.; Ritsema, J.; Fichtner, A.; Goes, S. D. B.

    2014-12-01

    Hotspot volcanism in locations such as Hawaii and Iceland is commonly thought to be associated with plumes rising from the deep mantle. In theory these dynamic upwellings should be visible in seismic data due to their reduced seismic velocity and their effect on mantle transition zone thickness. Numerous studies have attempted to image plumes [1,2,3], but their deep mantle origin remains unclear. In addition, a debate continues as to whether lower mantle plumes are visible in the form of body wave travel time delays, or whether such delays will be erased due to wavefront healing. Here we combine geodynamic modeling of mantle plumes with synthetic seismic waveform modeling in order to quantitatively determine under what conditions mantle plumes should be seismically visible. We model compressible plumes with phase changes at 410 km and 670 km, and a viscosity reduction in the upper mantle. These plumes thin from greater than 600 km in diameter in the lower mantle, to 200 - 400 km in the upper mantle. Plume excess potential temperature is 375 K, which maps to seismic velocity reductions of 4 - 12 % in the upper mantle, and 2 - 4 % in the lower mantle. Previous work that was limited to an axisymmetric spherical geometry suggested that these plumes would not be visible in the lower mantle [4]. Here we extend this approach to full 3D spherical wave propagation modeling. Initial results using a simplified cylindrical plume conduit suggest that mantle plumes with a diameter of 1000 km or greater will retain a deep mantle seismic signature. References[1] Wolfe, Cecily J., et al. "Seismic structure of the Iceland mantle plume." Nature 385.6613 (1997): 245-247. [2] Montelli, Raffaella, et al. "Finite-frequency tomography reveals a variety of plumes in the mantle." Science 303.5656 (2004): 338-343. [3] Schmandt, Brandon, et al. "Hot mantle upwelling across the 660 beneath Yellowstone." Earth and Planetary Science Letters 331 (2012): 224-236. [4] Hwang, Yong Keun, et al

  9. Turbulence statistics in a negatively buoyant particle plume - laboratory measurement

    Science.gov (United States)

    Bordoloi, Ankur; Clark, Laura; Veliz, Gerardo; Heath, Michael; Variano, Evan

    2016-11-01

    Negatively buoyant plumes of nylon particles are investigated in quiescent salt-water solution using flow visualization and stereoscopic PIV. Particles of the size 2 mm are continuously released through a nozzle from the top inside a water tank using a screw-conveyor based release mechanism. The plume propagates downward due to gravity, and by virtue of interacting particle wakes, becomes turbulent. The two phases are refractive index matched, so that the velocity field in the interstitial fluid can be quantified using PIV. We examine the velocity fields in the fluid phase to characterize turbulence statistics, such as turbulent kinetic energy, Reynolds stresses in the fully developed region of the plume. Further, we develop an image processing method to obtain particle distribution and particle slip inside the plume. In the presentation, we will discuss these results in the light of existing literature for rising plumes of bubbles under similar experimental conditions.

  10. Characterization of redox conditions in groundwater contaminant plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwarth, Steven A.

    2000-01-01

    Evaluation of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behaviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...... dubious, if not erroneous. Several other approaches have been used in addressing redox conditions in pollution plumes: redox-sensitive compounds in groundwater samples, hydrogen concentrations in groundwater, concentrations of volatile fatty acids in groundwater, sediment characteristics and microbial...... cases have been reported. No standardised or generally accepted approach exists. Slow electrode kinetics and the common lack of internal equilibrium of redox processes in pollution plumes make, with a few exceptions, direct electrochemical measurement and rigorous interpretation of redox potentials...

  11. Numerical Studies on Fire-induced Thermal Plumes

    Institute of Scientific and Technical Information of China (English)

    Junmei LI; Yanfeng LI; Wan Ki CHOW; Huairong HUANG

    2005-01-01

    Most of the expressions describing fire plumes reported in the literature are known to be based on experiments.Due to different experimental methods, the geometry of the fire sources, fuel types and surrounding conditions, it is difficult to derive a comprehensive picture of a plume with its temperature and velocity fields on the basis of existing theoretical work. Computational Fluid Dynamics (CFD), which is regarded as a practical engineering tool in fire engineering by the experts, is sure to be able to give more details of the plume behavior under various situations. Aerodynamics for thermally-induced plumes will be studied numerically with CFD. Four typical axisymmetric plume equations will be assessed in this paper, and investigations will be useful for fire engineers in designing smoke management systems in an affordable fashion. This is a critical point in implementing engineering performance-based fire code.

  12. Cluster Lenses

    CERN Document Server

    Kneib, Jean-Paul; 10.1007/s00159-011-0047-3

    2012-01-01

    Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity, given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple-images, and arclets. The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es) - understanding cluster mass distributions and issues pertaining...

  13. West Antarctic Mantle Plume Hypothesis and Basal Water Generation

    Science.gov (United States)

    Ivins, Erik; Seroussi, Helene; Wiens, Doug; Bondzio, Johannes

    2017-04-01

    The hypothesis of a deep mantle plume that manifests Pliocene and Quaternary volcanism and present-day seismicity in West Antarctica has been speculated for more than 30 years. Recent seismic images support the plume hypothesis as the cause of Marie Byrd Land (MBL) volcanism and geophysical structure [ Lloyd et al., 2015; Ramirez et al., 2016]. Mantle plumes can more that double the geothermal heat flux, qGHF, above nominal continental values at their axial peak position and raise qGHF in the surrounding plume head to 60 mW/m2 or higher. Unfortunately, there is a dearth of in-situ basal ice sheet data that sample the heat flux. Consequently, we examine a realistic distribution of heat flux associated with a late-Cenozoic mantle plume in West Antarctica and explore its impact on thermal and melt conditions near the ice sheet base. The solid Earth model assumes a parameterized deep mantle plume and head. The 3-D ice flow model includes an enthalpy framework and full-Stokes stress balance. Both the putative plume location and extent are uncertain. Therefore, we perform broadly scoped experiments to characterize plume related basal conditions. The experiments show that mantle plumes have an important local impact on the ice sheet, with basal melting rates reaching several centimeters per year directly above the hotspot. The downstream active lake system of Whillans Ice Stream suggests a rift-related source of anomalous mantle heat. However, the lack of lake and stream activity in MBL suggests a relatively weak plume: one that delivers less flux by 35% below the heat flux to the crustal surface at the site of the Yellowstone hotspot [e.g., DeNosaquo et al., 2009], with peak value no higher than about 145 mW/m2.

  14. A plume spectroscopy system for flight applications

    Science.gov (United States)

    Makel, D. B.; Petersen, T. V.; Duncan, D. B.; Madzsar, G. C.

    1993-06-01

    An operational plume spectroscopy system will be an important element of any rocket engine health management system (HMS). The flight capable FPI spectrometer will enable prognosis and response to incipient rocket engine failures as well as diagnosis of wear and degradation for on-condition maintenance. Spectrometer application to development programs, such as the Space Lifter, NASP, and SSTO, will reduce program risks, allow better adherence to schedules and save money by reducing or eliminating redesign and test costs. The diagnostic capability of a proven, calibrated spectrometer will enhance post-burn certification of high value, reusable engines, such as the Space Shuttle Main Engine (SSME), where life and reliability are key cost drivers. This paper describes a prototype FPI spectrometer for demonstration and validation testing on NASA's Technology Test Bed Engine (TTBE) at Marshall Space Flight Center. The TTBE test unit is designed with flight prototype optics and a commercial off-the-shelf data processing system.

  15. Identification of discontinuities in plasma plume evolution

    CERN Document Server

    Gojani, Ardian B; Obayashi, Shigeru

    2013-01-01

    The ejection of material during laser ablation gives rise to the development of discontinuities in the ambient gas. Several of these discontinuities are observed and characterized, including externally and internally propagating shock waves, contact surface, and the ionization front. Qualitative experimental observations and analysis of these discontinuities is presented. Results from shadowgraphy enabled determination of an irradiance threshold between two different ablation mechanisms, and determination of several stages of plasma plume evolution. Consideration of the refractive index as a dynamic sum of the contributions from gas and electrons led to separate identification of ionization front from the contact surface. Furthermore, ionization front was observed to lead the shock wave at the earlier stage of the ablation.

  16. Modeling contaminant plumes in fractured limestone aquifers

    DEFF Research Database (Denmark)

    Mosthaf, Klaus; Brauns, Bentje; Fjordbøge, Annika Sidelmann

    the established approaches of the equivalent porous medium, discrete fracture and dual continuum models. However, these modeling concepts are not well tested for contaminant plume migration in limestone geologies. Our goal was to develop and evaluate approaches for modeling the transport of dissolved contaminant...... in the planning of field tests and to update the conceptual model in an iterative process. Field data includes information on spill history, distribution of the contaminant (multilevel sampling), geology and hydrogeology. To describe the geology and fracture system, data from borehole logs, packer tests, optical...... distribution in the aquifer. Different models were used for the planning and interpretation of the pump and tracer test. The models were evaluated by examining their ability to describe collected field data. The comparison with data showed that the models have substantially different representations...

  17. Detecting Volcanic Ash Plumes with GNSS Signals

    Science.gov (United States)

    Rainville, N.; Larson, K. M.; Palo, S. E.; Mattia, M.; Rossi, M.; Coltelli, M.; Roesler, C.; Fee, D.

    2016-12-01

    Global Navigation Satellite Systems (GNSS) receivers are commonly placed near volcanic sites to measure ground deformation. In addition to the carrier phase data used to measure ground position, these receivers also record Signal to Noise ratio (SNR) data. Larson (2013) showed that attenuations in SNR data strongly correlate with ash emissions at a series of eruptions of Redoubt Volcano. This finding has been confirmed at eruptions for Tongariro, Mt Etna, Mt Shindake, and Sakurajima. In each of these detections, very expensive geodetic quality GNSS receivers were used. If low-cost GNSS instruments could be used instead, a networked array could be deployed and optimized for plume detection and tomography. The outputs of this sensor array could then be used by both local volcanic observatories and Volcano Ash Advisory Centers. Here we will describe progress in developing such an array. The sensors we are working with are intended for navigation use, and thus lack the supporting power and communications equipment necessary for a networked system. Reliably providing those features is major challenge for the overall sensor design. We have built prototypes of our Volcano Ash Plume Receiver (VAPR), with solar panels, lithium-ion batteries and onboard data storage for preliminary testing. We will present results of our field tests of both receivers and antennas. A second critical need for our array is a reliable detection algorithm. We have tested our algorithm on data from recent eruptions and have incorporated the noise characteristics of the low-cost GNSS receiver. We have also developed a simulation capability so that the receivers can be deployed to optimize vent crossing GNSS signals.

  18. Learning to Rapidly Re-Contact the Lost Plume in Chemical Plume Tracing

    Directory of Open Access Journals (Sweden)

    Meng-Li Cao

    2015-03-01

    Full Text Available Maintaining contact between the robot and plume is significant in chemical plume tracing (CPT. In the time immediately following the loss of chemical detection during the process of CPT, Track-Out activities bias the robot heading relative to the upwind direction, expecting to rapidly re-contact the plume. To determine the bias angle used in the Track-Out activity, we propose an online instance-based reinforcement learning method, namely virtual trail following (VTF. In VTF, action-value is generalized from recently stored instances of successful Track-Out activities. We also propose a collaborative VTF (cVTF method, in which multiple robots store their own instances, and learn from the stored instances, in the same database. The proposed VTF and cVTF methods are compared with biased upwind surge (BUS method, in which all Track-Out activities utilize an offline optimized universal bias angle, in an indoor environment with three different airflow fields. With respect to our experimental conditions, VTF and cVTF show stronger adaptability to different airflow environments than BUS, and furthermore, cVTF yields higher success rates and time-efficiencies than VTF.

  19. Data Clustering

    Science.gov (United States)

    Wagstaff, Kiri L.

    2012-03-01

    On obtaining a new data set, the researcher is immediately faced with the challenge of obtaining a high-level understanding from the observations. What does a typical item look like? What are the dominant trends? How many distinct groups are included in the data set, and how is each one characterized? Which observable values are common, and which rarely occur? Which items stand out as anomalies or outliers from the rest of the data? This challenge is exacerbated by the steady growth in data set size [11] as new instruments push into new frontiers of parameter space, via improvements in temporal, spatial, and spectral resolution, or by the desire to "fuse" observations from different modalities and instruments into a larger-picture understanding of the same underlying phenomenon. Data clustering algorithms provide a variety of solutions for this task. They can generate summaries, locate outliers, compress data, identify dense or sparse regions of feature space, and build data models. It is useful to note up front that "clusters" in this context refer to groups of items within some descriptive feature space, not (necessarily) to "galaxy clusters" which are dense regions in physical space. The goal of this chapter is to survey a variety of data clustering methods, with an eye toward their applicability to astronomical data analysis. In addition to improving the individual researcher’s understanding of a given data set, clustering has led directly to scientific advances, such as the discovery of new subclasses of stars [14] and gamma-ray bursts (GRBs) [38]. All clustering algorithms seek to identify groups within a data set that reflect some observed, quantifiable structure. Clustering is traditionally an unsupervised approach to data analysis, in the sense that it operates without any direct guidance about which items should be assigned to which clusters. There has been a recent trend in the clustering literature toward supporting semisupervised or constrained

  20. NW Iberia Shelf Dynamics. Study of the Douro River Plume.

    Directory of Open Access Journals (Sweden)

    Isabel Iglesias

    2014-06-01

    Full Text Available River plumes are one of the most important mechanisms that transport the terrestrial materials to the coast and the ocean. Some examples of those materials are pollutants, essential nutrients, which enhance the phytoplankton productivity or sediments, which settle on the seabed producing modifications on the bathymetry affecting the navigation channels. The mixing between the riverine and the oceanic waters can induce instabilities, which might generate bulges, filaments, and buoyant currents over the continental shelf. Offshore, the buoyant riverine water could form a front with the oceanic waters often related with the occurrence of current-jets, eddies and strong mixing. The study and modelling of the river plumes is a key factor for the complete understanding of sediment transport mechanisms and patterns, and of coastal physics and dynamic processes. On this study the Douro River plume will be simulated. The Douro River is located on the north-west Iberian coast and its daily averaged freshwater discharge can range values from 0 to 13000 m3/s. This variability impacts the formation of the river plumes and its dispersion along the continental shelf. This study builds on the long-term objective of generate a Douro River plume forecasting system as part of the RAIA and RAIA.co projects. Satellite imagery was analyzed showing that the river Douro is one of the main sources of suspended particles, dissolved material and chlorophyll in the NW Iberian Shelf. The Regional Oceanic Modeling System (ROMS model was selected to reproduce scenarios of plume generation, retention and dispersion. Whit this model, three types of simulations were performed: (i schematic winds simulations with prescribed river flow, wind speed and direction; (ii multi-year climatological simulation, with river flow and temperature change for each month; (iii extreme case simulation, based on the Entre-os-Rios accident situation. The schematic wind case-studies suggest that the

  1. Natural versus forced convection in laminar starting plumes

    CERN Document Server

    Rogers, Michael C

    2009-01-01

    A starting plume or jet has a well-defined, evolving head that is driven through the surrounding quiescent fluid by a localized flux of either buoyancy or momentum, or both. We studied the scaling and morphology of starting plumes produced by a constant flux of buoyant fluid from a small, submerged outlet. The plumes were laminar and spanned a wide range of plume Richardson numbers Ri. Ri is the dimensionless ratio of the buoyancy forces to inertial effects, and is thus our measurements crossed over the transition between buoyancy-driven plumes and momentum-driven jets. We found that the ascent velocity of the plume, nondimensionalized by Ri, exhibits a power law relationship with Re, the Reynolds number of the injected fluid in the outlet pipe. We also found that as the threshold between buoyancy-driven and momentum-driven flow was crossed, two distinct types of plume head mophologies existed: confined heads, produced in the Ri > 1 regime, and dispersed heads, which are found in the Ri < 1 regime. Head di...

  2. Biogeochemistry and isotope geochemistry of a landfill leachate plume.

    Science.gov (United States)

    van Breukelen, Boris M; Röling, Wilfred F M; Groen, Jacobus; Griffioen, Jasper; van Verseveld, Henk W

    2003-09-01

    The biogeochemical processes were identified which improved the leachate composition in the flow direction of a landfill leachate plume (Banisveld, The Netherlands). Groundwater observation wells were placed at specific locations after delineating the leachate plume using geophysical tests to map subsurface conductivity. Redox processes were determined using the distribution of solid and soluble redox species, hydrogen concentrations, concentration of dissolved gases (N(2), Ar, and CH(4)), and stable isotopes (delta15N-NO(3), delta34S-SO(4), delta13C-CH(4), delta2H-CH(4), and delta13C of dissolved organic and inorganic carbon (DOC and DIC, respectively)). The combined application of these techniques improved the redox interpretation considerably. Dissolved organic carbon (DOC) decreased downstream in association with increasing delta13C-DOC values confirming the occurrence of degradation. Degradation of DOC was coupled to iron reduction inside the plume, while denitrification could be an important redox process at the top fringe of the plume. Stable carbon and hydrogen isotope signatures of methane indicated that methane was formed inside the landfill and not in the plume. Total gas pressure exceeded hydrostatic pressure in the plume, and methane seems subject to degassing. Quantitative proof for DOC degradation under iron-reducing conditions could only be obtained if the geochemical processes cation exchange and precipitation of carbonate minerals (siderite and calcite) were considered and incorporated in an inverse geochemical model of the plume. Simulation of delta13C-DIC confirmed that precipitation of carbonate minerals happened.

  3. U. S. Air Force approach to plume contamination

    Science.gov (United States)

    Furstenau, Ronald P.; McCay, T. Dwayne; Mann, David M.

    1980-08-01

    Exhaust products from rocket engine firings can produce undesirable effects on sensitive satellite surfaces, such as optical systems, solar cells, and thermal control surfaces. The Air Force has an objective of minimizing the effect of rocket plume contamination on space-craft mission effectiveness. Plume contamination can result from solid rocket motors, liquid propellant engines, and electric thrusters. To solve the plume contamination problem, the Air Force Rocket Propulsion Laboratory (AFRPL) has developed a plume contamination computer model which predicts the production, transport, and deposition of rocket exhaust products. In addition, an experimental data base is being obtained through ground-based vacuum chamber experiments and in-flight measurements with which to compare the analytical results. Finally, the experimental data is being used to verify and improve the analytical model. The plume contamination model, known as CONTAM, has been used to make contamination predictions for various engines. The experimental programs have yielded quantitative data, such as species concentrations and temperatures, in all regions of the plume. The result of the modelling and experimental programs will ultimately be computer models which can be used by the satellite designer to analyze and to minimize the effect plume contamination will have on a particular spacecraft system.

  4. Monitoring radioactive plumes by airborne gamma-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Grasty, R.L. [Exploranium, Mississauga, Ontario (Canada); Hovgaard, J. [Danish Emergency Management Agency, Birkerod (Germany); Multala, J. [Geological Survey of Finland, Espoo (Finland)

    1996-06-01

    Airborne gamma-ray spectrometer surveys using large volume sodium-iodide detectors are routinely flown throughout the world for mineral exploration and geological mapping. Techniques have now been developed to detect and map man-made sources of radiation. In Canada, airborne gamma-rays surveys have been flown around nuclear reactors to map {sup 41}Ar plumes from nuclear reactors and to calculate the dose rate at ground level. In May 1986, the Finnish Geological survey aircraft flew through a radioactive plume from the Chernobyl nuclear accident. As the aircraft flew through the plume, the aircraft became increasingly contaminated. By measuring the final aircraft contamination, the activity of the plume could be separated from the contamination due to the aircraft. Within 1 h of encountering the plume, the aircraft activity was comparable to the maximum levels found in the plume. From an analysis of the gamma-ray spectra, the concentration of {sup 131}I and {sup 140}La within the plume were calculated as a function of time.

  5. Cooling tower and plume modeling for satellite remote sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Powers, B.J.

    1995-05-01

    It is often useful in nonproliferation studies to be able to remotely estimate the power generated by a power plant. Such information is indirectly available through an examination of the power dissipated by the plant. Power dissipation is generally accomplished either by transferring the excess heat generated into the atmosphere or into bodies of water. It is the former method with which we are exclusively concerned in this report. We discuss in this report the difficulties associated with such a task. In particular, we primarily address the remote detection of the temperature associated with the condensed water plume emitted from the cooling tower. We find that the effective emissivity of the plume is of fundamental importance for this task. Having examined the dependence of the plume emissivity in several IR bands and with varying liquid water content and droplet size distributions, we conclude that the plume emissivity, and consequently the plume brightness temperature, is dependent upon not only the liquid water content and band, but also upon the droplet size distribution. Finally, we discuss models dependent upon a detailed point-by-point description of the hydrodynamics and thermodynamics of the plume dynamics and those based upon spatially integrated models. We describe in detail a new integral model, the LANL Plume Model, which accounts for the evolution of the droplet size distribution. Some typical results obtained from this model are discussed.

  6. Cluster Chemistry

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ Cansisting of eight scientists from the State Key Laboratory of Physical Chemistry of Solid Surfaces and Xiamen University, this creative research group is devoted to the research of cluster chemistry and creation of nanomaterials.After three-year hard work, the group scored a series of encouraging progresses in synthesis of clusters with special structures, including novel fullerenes, fullerene-like metal cluster compounds as well as other related nanomaterials, and their properties study.

  7. A mantle plume beneath California? The mid-Miocene Lovejoy Flood Basalt, northern California

    Science.gov (United States)

    Garrison, N.J.; Busby, C.J.; Gans, P.B.; Putirka, K.; Wagner, D.L.

    2008-01-01

    The Lovejoy basalt represents the largest eruptive unit identified in California, and its age, volume, and chemistry indicate a genetic affinity with the Columbia River Basalt Group and its associated mantle-plume activity. Recent field mapping, geochemical analyses, and radiometric dating suggest that the Lovejoy basalt erupted during the mid-Miocene from a fissure at Thompson Peak, south of Susanville, California. The Lovejoy flowed through a paleovalley across the northern end of the Sierra Nevada to the Sacramento Valley, a distance of 240 km. Approximately 150 km3 of basalt were erupted over a span of only a few centuries. Our age dates for the Lovejoy basalt cluster are near 15.4 Ma and suggest that it is coeval with the 16.1-15.0 Ma Imnaha and Grande Ronde flows of the Columbia River Basalt Group. Our new mapping and age dating support the interpretation that the Lovejoy basalt erupted in a forearc position relative to the ancestral Cascades arc, in contrast with the Columbia River Basalt Group, which erupted in a backarc position. The arc front shifted trenchward into the Sierran block after 15.4 Ma. However, the Lovejoy basalt appears to be unrelated to volcanism of the predominantly calc-alkaline Cascade arc; instead, the Lovejoy is broadly tholeiitic, with trace-element characteristics similar to the Columbia River Basalt Group. Association of the Lovejoy basalt with mid-Miocene flood basalt volcanism has considerable implications for North American plume dynamics and strengthens the thermal "point source" explanation, as provided by the mantle-plume hypothesis. Alternatives to the plume hypothesis usually call upon lithosphere-scale cracks to control magmatic migrations in the Yellowstone-Columbia River basalt region. However, it is difficult to imagine a lithosphere-scale flaw that crosses Precambrian basement and accreted terranes to reach the Sierra microplate, where the Lovejoy is located. Therefore, we propose that the Lovejoy represents a rapid

  8. 3-D numerical modeling of plume-induced subduction initiation

    Science.gov (United States)

    Baes, Marzieh; Gerya, taras; Sobolev, Stephan

    2016-04-01

    Investigation of mechanisms involved in formation of a new subduction zone can help us to better understand plate tectonics. Despite numerous previous studies, it is still unclear how and where an old oceanic plate starts to subduct beneath the other plate. One of the proposed scenarios for nucleation of subduction is plume-induced subduction initiation, which was investigated in detail, using 2-D models, by Ueda et al. (2008). Recently. Gerya et al. (2015), using 3D numerical models, proposed that plume-lithosphere interaction in the Archean led to the subduction initiation and onset of plate tectonic. In this study, we aim to pursue work of Ueda et al. (2008) by incorporation of 3-D thermo-mechanical models to investigate conditions leading to oceanic subduction initiation as a result of thermal-chemical mantle plume-lithosphere interaction in the modern earth. Results of our experiments show four different deformation regimes in response to plume-lithosphere interaction, that are a) self-sustaining subduction initiation where subduction becomes self-sustained, b) freezing subduction initiation where subduction stops at shallow depths, c) slab break-off where subducting circular slab breaks off soon after formation and d) plume underplating where plume does not pass through the lithosphere but spreads beneath it (failed subduction initiation). These different regimes depend on several parameters such as plume's size, composition and temperature, lithospheric brittle/plastic strength, age of the oceanic lithosphere and presence/absence of lithospheric heterogeneities. Results show that subduction initiates and becomes self-sustained when lithosphere is older than 10 Myr and non-dimensional ratio of the plume buoyancy force and lithospheric strength above the plume is higher than 2.

  9. Multiphase CFD modeling of nearfield fate of sediment plumes

    DEFF Research Database (Denmark)

    Saremi, Sina; Hjelmager Jensen, Jacob

    2014-01-01

    Disposal of dredged material and the overflow discharge during the dredging activities is a matter of concern due to the potential risks imposed by the plumes on surrounding marine environment. This gives rise to accurately prediction of the fate of the sediment plumes released in ambient waters....... The two-phase mixture solution based on the drift-flux method is evaluated for 3D simulation of material disposal and overflow discharge from the hoppers. The model takes into account the hindrance and resistance mechanisms in the mixture and is capable of describing the flow details within the plumes...... and gives excellent results when compared to experimental data....

  10. Airborne Gamma-ray Measurements in the Chernobyl Plume

    DEFF Research Database (Denmark)

    Grasty, R. L.; Hovgaard, Jens; Multala, J.

    1997-01-01

    On 29 April 1986, the Geological Survey of Finland (GSF) survey aircraft with a gamma ray spectrometer flew through a radioactive plume from the Chernobyl nuclear accident. The aircraft became contaminated and the gamma spectrometer measured radioactivity in the plume as well as radioactivity...... on the aircraft. By using simple assumptions on the build-up of contamination it has been possible to separate the signals from contamination and from plume. The analysis further showed that even a detector/spectrometer with low energy resolution is able to identify a contamination with iodine....

  11. Standoff midwave infrared hyperspectral imaging of ship plumes

    Science.gov (United States)

    Gagnon, Marc-André; Gagnon, Jean-Philippe; Tremblay, Pierre; Savary, Simon; Farley, Vincent; Guyot, Éric; Lagueux, Philippe; Chamberland, Martin; Marcotte, Frédérick

    2016-05-01

    Characterization of ship plumes is very challenging due to the great variety of ships, fuel, and fuel grades, as well as the extent of a gas plume. In this work, imaging of ship plumes from an operating ferry boat was carried out using standoff midwave (3-5 μm) infrared hyperspectral imaging. Quantitative chemical imaging of combustion gases was achieved by fitting a radiative transfer model. Combustion efficiency maps and mass flow rates are presented for carbon monoxide (CO) and carbon dioxide (CO2). The results illustrate how valuable information about the combustion process of a ship engine can be successfully obtained using passive hyperspectral remote sensing imaging.

  12. Laboratory Study of Dispersion of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Petersen, Ole; Larsen, Torben

    1990-01-01

    A laboratory a study on surface dispersion of buoyant plumes in open channel turbulence in made, where the buoyancy is due to both salinity and heat. The measured parameters are the downstream derivative of a plume width and height, which are integral-characteristics of the distributions of density......-differences. Other methods as infra-red sensing are used for visualizing purpose. The results are used to calibrate an integral model of the dispersion. Conclusions are that the dispersion of a buoyant surface plume can be treated the superposition of a buoyancy induced stretching and turbulent diffusion, reduced...

  13. Lightning in Colorado forest fire smoke plumes during summer 2012

    Science.gov (United States)

    Lang, T. J.; Krehbiel, P. R.; Dolan, B.; Lindsey, D.; Rutledge, S. A.; Rison, W.

    2012-12-01

    May and June 2012 were unusually hot and dry in Colorado, which was suffering from a strong drought. A major consequence of this climatic regime was one of the most destructive forest fire seasons in state history, with hundreds of thousands of acres of forest and grassland consumed by flames, hundreds of homes burned, and several lives lost. Many of these fires occurred within range of the newly installed Colorado Lightning Mapping Array (COLMA), which provides high-resolution observations of discharges over a large portion of the state. The COLMA was installed in advance of the Deep Convective Clouds and Chemistry (DC3) project. High-altitude lightning was observed to occur sporadically in the smoke plumes over three major fires that occurred during early summer: Hewlett Gulch, High Park, and Waldo Canyon. Additionally, the Colorado State University CHILL (CSU-CHILL) and Pawnee radars observed the Hewlett Gulch plume electrify with detailed polarimetric and dual-Doppler measurements, and also provided these same measurements for the High Park plume when it was not producing lightning. Meanwhile, local Next Generation Radars (NEXRADs) provided observations of the electrified High Park and Waldo Canyon plumes. All of these plumes also were observed by geostationary meteorological satellites. These observations provide an unprecedented dataset with which to study smoke plume and pyrocumulus electrification. The polarimetric data - low reflectivity, high differential reflectivity, low correlation coefficient, and noisy differential phase - were consistent with the smoke plumes and associated pyrocumulus being filled primarily with irregularly shaped ash particles. Lightning was not observed in the plumes until they reached over 10 km above mean sea level, which was an uncommon occurrence requiring explosive fire growth combined with increased meteorological instability and reduced wind shear. Plume updraft intensification and echo-top growth led the occurrence of

  14. Rocket Plume Scaling for Orion Wind Tunnel Testing

    Science.gov (United States)

    Brauckmann, Gregory J.; Greathouse, James S.; White, Molly E.

    2011-01-01

    A wind tunnel test program was undertaken to assess the jet interaction effects caused by the various solid rocket motors used on the Orion Launch Abort Vehicle (LAV). These interactions of the external flowfield and the various rocket plumes can cause localized aerodynamic disturbances yielding significant and highly non-linear control amplifications and attenuations. This paper discusses the scaling methodologies used to model the flight plumes in the wind tunnel using cold air as the simulant gas. Comparisons of predicted flight, predicted wind tunnel, and measured wind tunnel forces-and-moments and plume flowfields are made to assess the effectiveness of the selected scaling methodologies.

  15. Clustered regression with unknown clusters

    CERN Document Server

    Barman, Kishor

    2011-01-01

    We consider a collection of prediction experiments, which are clustered in the sense that groups of experiments ex- hibit similar relationship between the predictor and response variables. The experiment clusters as well as the regres- sion relationships are unknown. The regression relation- ships define the experiment clusters, and in general, the predictor and response variables may not exhibit any clus- tering. We call this prediction problem clustered regres- sion with unknown clusters (CRUC) and in this paper we focus on linear regression. We study and compare several methods for CRUC, demonstrate their applicability to the Yahoo Learning-to-rank Challenge (YLRC) dataset, and in- vestigate an associated mathematical model. CRUC is at the crossroads of many prior works and we study several prediction algorithms with diverse origins: an adaptation of the expectation-maximization algorithm, an approach in- spired by K-means clustering, the singular value threshold- ing approach to matrix rank minimization u...

  16. Subspace clustering through attribute clustering

    Institute of Scientific and Technical Information of China (English)

    Kun NIU; Shubo ZHANG; Junliang CHEN

    2008-01-01

    Many recently proposed subspace clustering methods suffer from two severe problems. First, the algorithms typically scale exponentially with the data dimensionality or the subspace dimensionality of clusters. Second, the clustering results are often sensitive to input parameters. In this paper, a fast algorithm of subspace clustering using attribute clustering is proposed to over-come these limitations. This algorithm first filters out redundant attributes by computing the Gini coefficient. To evaluate the correlation of every two non-redundant attributes, the relation matrix of non-redundant attributes is constructed based on the relation function of two dimensional united Gini coefficients. After applying an overlapping clustering algorithm on the relation matrix, the candidate of all interesting subspaces is achieved. Finally, all subspace clusters can be derived by clustering on interesting subspaces. Experiments on both synthesis and real datasets show that the new algorithm not only achieves a significant gain of runtime and quality to find subspace clusters, but also is insensitive to input parameters.

  17. Eastern Dharwar Craton, India: Continental lithosphere growth by accretion of diverse plume and arc terranes

    Directory of Open Access Journals (Sweden)

    C. Manikyamba

    2012-05-01

    Archean lithospheric mantle, distinctive in being thick, refractory, and buoyant, formed complementary to the accreted plume and convergent margin terranes, as migrating arcs captured thick plume-plateaus, and the refractory, low density, residue of plume melting coupled with accreted imbricated plume-arc crust.

  18. Linking Europa's plume activity to tides, tectonics, and liquid water

    CERN Document Server

    Rhoden, Alyssa R; Roth, Lorenz; Retherford, Kurt

    2015-01-01

    Much of the geologic activity preserved on Europa's icy surface has been attributed to tidal deformation, mainly due to Europa's eccentric orbit. Although the surface is geologically young (30 - 80 Myr), there is little information as to whether tidally-driven surface processes are ongoing. However, a recent detection of water vapor near Europa's south pole suggests that it may be geologically active. Initial observations indicated that Europa's plume eruptions are time-variable and may be linked to its tidal cycle. Saturn's moon, Enceladus, which shares many similar traits with Europa, displays tidally-modulated plume eruptions, which bolstered this interpretation. However, additional observations of Europa at the same time in its orbit failed to yield a plume detection, casting doubt on the tidal control hypothesis. The purpose of this study is to analyze the timing of plume eruptions within the context of Europa's tidal cycle to determine whether such a link exists and examine the inferred similarities and...

  19. Saturated Zone Plumes in Volcanic Rock: Implications for Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    S. Kelkar; R. Roback; B. Robinson; G. Srinivasan; C. Jones; P. Reimus

    2006-02-14

    This paper presents a literature survey of the occurrences of radionuclide plumes in saturated, fractured rocks. Three sites, Idaho National laboratory, Hanford, and Oak Ridge are discussed in detail. Results of a modeling study are also presented showing that the length to width ratio of a plume starting within the repository footprint at the Yucca Mountain Project site, decreases from about 20:1 for the base case to about 4:1 for a higher value of transverse dispersivity, indicating enhanced lateral spreading of the plume. Due to the definition of regulatory requirements, this lateral spreading does not directly impact breakthrough curves at the 18 km compliance boundary, however it increases the potential that a plume will encounter reducing conditions, thus significantly retarding the transport of sorbing radionuclides.

  20. Effects of rotation on turbulent buoyant plumes in stratified environments

    National Research Council Canada - National Science Library

    Fabregat Tomàs, Alexandre; Poje, Andrew C; Özgökmen, Tamay M; Dewar, William K

    2016-01-01

    We numerically investigate the effects of rotation on the turbulent dynamics of thermally driven buoyant plumes in stratified environments at the large Rossby numbers characteristic of deep oceanic releases...

  1. False alarm recognition in hyperspectral gas plume identification

    Science.gov (United States)

    Conger, James L [San Ramon, CA; Lawson, Janice K [Tracy, CA; Aimonetti, William D [Livermore, CA

    2011-03-29

    According to one embodiment, a method for analyzing hyperspectral data includes collecting first hyperspectral data of a scene using a hyperspectral imager during a no-gas period and analyzing the first hyperspectral data using one or more gas plume detection logics. The gas plume detection logic is executed using a low detection threshold, and detects each occurrence of an observed hyperspectral signature. The method also includes generating a histogram for all occurrences of each observed hyperspectral signature which is detected using the gas plume detection logic, and determining a probability of false alarm (PFA) for all occurrences of each observed hyperspectral signature based on the histogram. Possibly at some other time, the method includes collecting second hyperspectral data, and analyzing the second hyperspectral data using the one or more gas plume detection logics and the PFA to determine if any gas is present. Other systems and methods are also included.

  2. A Thermal Plume Model for the Martian Convective Boundary Layer

    CERN Document Server

    Colaïtis, Arnaud; Hourdin, Frédéric; Rio, Catherine; Forget, François; Millour, Ehouarn

    2013-01-01

    The Martian Planetary Boundary Layer [PBL] is a crucial component of the Martian climate system. Global Climate Models [GCMs] and Mesoscale Models [MMs] lack the resolution to predict PBL mixing which is therefore parameterized. Here we propose to adapt the "thermal plume" model, recently developed for Earth climate modeling, to Martian GCMs, MMs, and single-column models. The aim of this physically-based parameterization is to represent the effect of organized turbulent structures (updrafts and downdrafts) on the daytime PBL transport, as it is resolved in Large-Eddy Simulations [LESs]. We find that the terrestrial thermal plume model needs to be modified to satisfyingly account for deep turbulent plumes found in the Martian convective PBL. Our Martian thermal plume model qualitatively and quantitatively reproduces the thermal structure of the daytime PBL on Mars: superadiabatic near-surface layer, mixing layer, and overshoot region at PBL top. This model is coupled to surface layer parameterizations taking ...

  3. Tracking hydrocarbon plume transport and biodegradation at Deepwater Horizon.

    Science.gov (United States)

    Camilli, Richard; Reddy, Christopher M; Yoerger, Dana R; Van Mooy, Benjamin A S; Jakuba, Michael V; Kinsey, James C; McIntyre, Cameron P; Sylva, Sean P; Maloney, James V

    2010-10-08

    The Deepwater Horizon blowout is the largest offshore oil spill in history. We present results from a subsurface hydrocarbon survey using an autonomous underwater vehicle and a ship-cabled sampler. Our findings indicate the presence of a continuous plume of oil, more than 35 kilometers in length, at approximately 1100 meters depth that persisted for months without substantial biodegradation. Samples collected from within the plume reveal monoaromatic petroleum hydrocarbon concentrations in excess of 50 micrograms per liter. These data indicate that monoaromatic input to this plume was at least 5500 kilograms per day, which is more than double the total source rate of all natural seeps of the monoaromatic petroleum hydrocarbons in the northern Gulf of Mexico. Dissolved oxygen concentrations suggest that microbial respiration rates within the plume were not appreciably more than 1 micromolar oxygen per day.

  4. False alarm recognition in hyperspectral gas plume identification

    Energy Technology Data Exchange (ETDEWEB)

    Conger, James L. (San Ramon, CA); Lawson, Janice K. (Tracy, CA); Aimonetti, William D. (Livermore, CA)

    2011-03-29

    According to one embodiment, a method for analyzing hyperspectral data includes collecting first hyperspectral data of a scene using a hyperspectral imager during a no-gas period and analyzing the first hyperspectral data using one or more gas plume detection logics. The gas plume detection logic is executed using a low detection threshold, and detects each occurrence of an observed hyperspectral signature. The method also includes generating a histogram for all occurrences of each observed hyperspectral signature which is detected using the gas plume detection logic, and determining a probability of false alarm (PFA) for all occurrences of each observed hyperspectral signature based on the histogram. Possibly at some other time, the method includes collecting second hyperspectral data, and analyzing the second hyperspectral data using the one or more gas plume detection logics and the PFA to determine if any gas is present. Other systems and methods are also included.

  5. Volcanic ash plume identification using polarization lidar: Augustine eruption, Alaska

    Science.gov (United States)

    Sassen, Kenneth; Zhu, Jiang; Webley, Peter W.; Dean, K.; Cobb, Patrick

    2007-01-01

    During mid January to early February 2006, a series of explosive eruptions occurred at the Augustine volcanic island off the southern coast of Alaska. By early February a plume of volcanic ash was transported northward into the interior of Alaska. Satellite imagery and Puff volcanic ash transport model predictions confirm that the aerosol plume passed over a polarization lidar (0.694 mm wavelength) site at the Arctic Facility for Atmospheric Remote Sensing at the University of Alaska Fairbanks. For the first time, lidar linear depolarization ratios of 0.10 – 0.15 were measured in a fresh tropospheric volcanic plume, demonstrating that the nonspherical glass and mineral particles typical of volcanic eruptions generate strong laser depolarization. Thus, polarization lidars can identify the volcanic ash plumes that pose a threat to jet air traffic from the ground, aircraft, or potentially from Earth orbit.

  6. Destratification induced by bubble plumes as a means to reduce ...

    African Journals Online (AJOL)

    to reduce evaporation from open impoundments. M van Dijk* and SJ van .... The air injection bubble plume system used for water quality applications has been ...... ervoir Evaporation Utilizing Mass Transfer Theory. US Geological. Survey.

  7. Hydrocarbon Rocket Engine Plume Imaging with Laser Induced Incandescence Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA/ Marshall Space Flight Center (MSFC) needs sensors that can be operated on rocket engine plume environments to improve NASA/SSC rocket engine performance. In...

  8. Vertically Discontinuous Seismic Signatures From Continuous Thermochemical Plumes

    Science.gov (United States)

    Harris, A. C.; Kincaid, C.; Savage, B.

    2008-12-01

    To interpret seismic signatures associated with mantle upwellings, we must understand the distribution of thermochemical heterogeneities within mantle plumes. Thermochemical heterogeneities are expected to arise within plumes by the incorporation of subducted lithosphere (Eclogite and Harzburgite) that has reached the plume source region (thermal boundary layers in the mantle). We analyze laboratory experiments in conjunction with seismic velocity models to predict the seismic signature of thermochemical plumes. Laboratory experiments are fully three-dimensional and use glucose syrup (Rayleigh number: 106) to model the mantle and a two-layer subducted lithosphere, where composition (viscosity and density) is controlled by water content. Experiments show heterogeneous upwellings with variations in both temperature and composition that are more complex than predicted in previous plume models. Spatial distributions for temperature and composition in representative, repeatable types of thermochemical upwellings are tracked through time, scaled to mantle values and used to calculate predicted seismic velocities. Apparent seismic velocity signals are estimated for patterns in thermochemical heterogeneity with length scales ranging from 1 to 300 km and excess temperatures from 50 to 300°C. Results show that if plumes are purely thermal they can be identified in the usual way, by slow velocities. However, if plumes are a mixture of compositions, as predicted by laboratory models, their velocity structure is more complex. An Ecolgite lens within a plume at ~300km depth with an excess temperature of 250°C can have the same velocity as regular mantle with no excess temperature. A Harzburgite lobe of a plume head (up to half of the plume volume) at 300km depth with an excess temperature of 225°C can have the same Vs as regular mantle with no excess temperature, but can only mask up to 55°C in Vp. Spatial variations in temperature control velocity structure above 300km

  9. Site characterization and petroleum hydrocarbon plume mapping

    Energy Technology Data Exchange (ETDEWEB)

    Ravishankar, K. [Harding Lawson Associates, Houston, TX (United States)

    1996-12-31

    This paper presents a case study of site characterization and hydrocarbon contamination plume mapping/delineation in a gas processing plant in southern Mexico. The paper describes innovative and cost-effective use of passive (non-intrusive) and active (intrusive) techniques, including the use of compound-specific analytical methods for site characterization. The techniques used, on a demonstrative basis, include geophysical, geochemical, and borehole drilling. Geochemical techniques used to delineate the horizontal extent of hydrocarbon contamination at the site include soil gas surveys. The borehole drilling technique used to assess the vertical extent of contamination and confirm geophysical and geochemical data combines conventional hollow-stem auguring with direct push-probe using Geoprobe. Compound-specific analytical methods, such as hydrocarbon fingerprinting and a modified method for gasoline range organics, demonstrate the inherent merit and need for such analyses to properly characterize a site, while revealing the limitations of noncompound-specific total petroleum hydrocarbon analysis. The results indicate that the techniques used in tandem can properly delineate the nature and extent of contamination at a site; often supplement or complement data, while reducing the risk of errors and omissions during the assessment phase; and provide data constructively to focus site-specific remediation efforts. 7 figs.

  10. Evolution of particle size in turbid discharge plumes

    Science.gov (United States)

    2016-06-07

    Evolution of particle size in turbid discharge plumes Paul S. Hill Department of Oceanography Dalhousie University Halifax, Nova Scotia, CANADA B3H...COVERED 00-00-1999 to 00-00-1999 4. TITLE AND SUBTITLE Evolution of particle size in turbid discharge plumes 5a. CONTRACT NUMBER 5b. GRANT...experiment was designed to explore the evolution of disaggregated grain size distribution in a flowing suspension. RESULTS Bulk effective settling

  11. The Communicating Pipe Model for Icy Plumes on Enceladus

    Institute of Scientific and Technical Information of China (English)

    MA Qian-Li; CHEN Chu-Xin

    2009-01-01

    We analyze the communicating pipe model on Enceladus, and predict that Saturn's strong tidal force in Enceladus plays a significant role in the plumes. In this model, the scale of the volcanoes can be evaluated based on the history of the craters and plumes. The correspondence of the data and observation make the model valid for the eruption. So it is imaginable that the tidal force is pulling the liquid out through the communicating pipe while reshaping the surface on Enceladus.

  12. Chemical Plume Detection with an Iterative Background Estimation Technique

    Science.gov (United States)

    2016-05-17

    this paper, we focus on cases where the plume is large (relative to the image ), and provide a method for handling this scenario. The method we develop...the locations of the events, the operation in (11) is a convolution of a binary image with a filter function h. To get an estimate of the probability...background statistics, including the mean and covariance. Diffuse plumes with a large spatial extent are particularly difficult to detect in single- image

  13. Multiple Factor Analysis and k-Means Clustering-Based Classification of the DOE Groundwater Contaminant Database

    Science.gov (United States)

    Faybishenko, B.; Hazen, T. C.

    2009-12-01

    , between the types of contaminant groups and the contamination severity. The relationships between contaminant groups and the plume depth and velocity, and contaminant groups and climate are weak, and there is no a significant relationship with the plume volumes. To visualize the contribution of different factors, the results of MFA calculations are presented using two- and three-dimensional maps. Using the first four factors for the basic plume characteristics, a k-means cluster analysis was applied to classify the plumes into respective clusters. These results can be used to plan characterization, monitoring, and modeling of contaminant behavior at contaminated sites, and to design appropriate remediation technologies.

  14. Mapping the Hawaiian plume conduit with converted seismic waves

    Science.gov (United States)

    Li; Kind; Priestley; Sobolev; Tilmann; Yuan; Weber

    2000-06-22

    The volcanic edifice of the Hawaiian islands and seamounts, as well as the surrounding area of shallow sea floor known as the Hawaiian swell, are believed to result from the passage of the oceanic lithosphere over a mantle hotspot. Although geochemical and gravity observations indicate the existence of a mantle thermal plume beneath Hawaii, no direct seismic evidence for such a plume in the upper mantle has yet been found. Here we present an analysis of compressional-to-shear (P-to-S) converted seismic phases, recorded on seismograph stations on the Hawaiian islands, that indicate a zone of very low shear-wave velocity (effects of the Hawaiian plume conduit in the asthenosphere and mantle transition zone with excess temperature of approximately 300 degrees C. Large variations in the transition-zone thickness suggest a lower-mantle origin of the Hawaiian plume similar to the Iceland plume, but our results indicate a 100 degrees C higher temperature for the Hawaiian plume.

  15. THE FLOW PATTERNS OF BUBBLE PLUME IN AN MBBR

    Institute of Scientific and Technical Information of China (English)

    LI Shi-rong; CHENG Wen; WANG Meng; CHEN Chen

    2011-01-01

    The flow patterns of the gas-liquid two-phase flow in a Moving-Bed Biofilm Reactor(MBBR)have a critical effect upon the mass transfer by the convection.Bubble plumes promote unsteadily fluctuating two-phase flows during the aeration.This article studies the unsteady structure of bubble plumes through experiments.The time-serial bubble plume images in various cases of the tank are analyzed.The Recursive Cross Correlation-Particle Image Velocimetry(RCC-PIV)is used to calculate the velocities in those cases,and then the time-serial vortex,the total turbulence intensity,the time-serial streamline are obtained.It is shown that the aspect ratio and the void fraction are the dominant factors influencing the unsteady structure of bubble plumes.When the aspect ratio is unity and the void fraction is high,the bubble plumes see a symmetrical vortex structure with a long residence time,which is beneficial for optimizing the aeration system and enhancing the applied range of bubble plumes.

  16. P- and S-wave delays caused by thermal plumes

    Science.gov (United States)

    Maguire, Ross; Ritsema, Jeroen; van Keken, Peter E.; Fichtner, Andreas; Goes, Saskia

    2016-08-01

    Many studies have sought to seismically image plumes rising from the deep mantle in order to settle the debate about their presence and role in mantle dynamics, yet the predicted seismic signature of realistic plumes remains poorly understood. By combining numerical simulations of flow, mineral-physics constraints on the relationships between thermal anomalies and wave speeds, and spectral-element method based computations of seismograms, we estimate the delay times of teleseismic S and P waves caused by thermal plumes. Wave front healing is incomplete for seismic periods ranging from 10 s (relevant in traveltime tomography) to 40 s (relevant in waveform tomography). We estimate P-wave delays to be immeasurably small (20 s), measurements of instantaneous phase misfit may be more useful in resolving narrow plume conduits. To detect S-wave delays of 0.4-0.8 s and the diagnostic frequency dependence imparted by plumes, it is key to minimize the influence of the heterogeneous crust and upper mantle. We argue that seismic imaging of plumes will advance significantly if data from wide-aperture ocean-bottom networks were available since, compared to continents, the oceanic crust and upper mantle are relatively simple.

  17. Plume aerodynamic effects of cushion engine in lunar landing

    Institute of Scientific and Technical Information of China (English)

    He Bijiao; He Xiaoying; Zhang Mingxing; Cai Guobiao

    2013-01-01

    During the second period of China “Tanyue” Project,the explorer will softland on the moon.The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground.It is necessary to study its plume effects on the explorer component.The self-developed PWS (Plume WorkStation) software based on direct simulation Monte Carlo (DSMC) method is used to simulate the plume effects of two 150 N engines.Due to the complex structure of the explorer,PWS uses a decoupling method to treat the boundary mesh,which mainly interacts with simulation particles,and has no relation with the computational grids.After the analytical expressions of plane surfaces and curved surfaces of each boundary block are given,the particle position within or without the boundary blocks can be easily determined.Finally the 3D plume field of two 150 N engines is simulated.The pressure,temperature and velocity distributions of plume field are clearly presented by three characteristic slices.The aerodynamic effects on the explorer bottom,the landfall legs and antenna are separately shown.The compression influence on the plume flow of four landfall legs can be observed.

  18. Growth and mixing dynamics of mantle wedge plumes

    Science.gov (United States)

    Gorczyk, Weronika; Gerya, Taras V.; Connolly, James A. D.; Yuen, David A.

    2007-07-01

    Recent work suggests that hydrated partially molten thermal-chemical plumes that originate from subducted slab as a consequence of Rayleigh-Taylor instability are responsible for the heterogeneous composition of the mantle wedge. We use a two-dimensional ultrahigh-resolution numerical simulation involving 10 × 109 active markers to anticipate the detailed evolution of the internal structure of natural plumes beneath volcanic arcs in intraoceanic subduction settings. The plumes consist of partially molten hydrated peridotite, dry solid mantle, and subducted oceanic crust, which may compose as much as 12% of the plume. As plumes grow and mature these materials mix chaotically, resulting in attenuation and duplication of the original layering on scales of 1-1000 m. Comparison of numerical results with geological observations from the Horoman ultramafic complex in Japan suggests that mixing and differentiation processes related to development of partially molten plumes above slabs may be responsible for the strongly layered lithologically mixed (marble cake) structure of asthenospheric mantle wedges.

  19. Influence of mass transfer on bubble plume hydrodynamics

    Directory of Open Access Journals (Sweden)

    IRAN E. LIMA NETO

    2016-03-01

    Full Text Available ABSTRACT This paper presents an integral model to evaluate the impact of gas transfer on the hydrodynamics of bubble plumes. The model is based on the Gaussian type self-similarity and functional relationships for the entrainment coefficient and factor of momentum amplification due to turbulence. The impact of mass transfer on bubble plume hydrodynamics is investigated considering different bubble sizes, gas flow rates and water depths. The results revealed a relevant impact when fine bubbles are considered, even for moderate water depths. Additionally, model simulations indicate that for weak bubble plumes (i.e., with relatively low flow rates and large depths and slip velocities, both dissolution and turbulence can affect plume hydrodynamics, which demonstrates the importance of taking the momentum amplification factor relationship into account. For deeper water conditions, simulations of bubble dissolution/decompression using the present model and classical models available in the literature resulted in a very good agreement for both aeration and oxygenation processes. Sensitivity analysis showed that the water depth, followed by the bubble size and the flow rate are the most important parameters that affect plume hydrodynamics. Lastly, dimensionless correlations are proposed to assess the impact of mass transfer on plume hydrodynamics, including both the aeration and oxygenation modes.

  20. A computational scheme usable for calculating the plume backflow region

    Science.gov (United States)

    Cooper, B. P., Jr.

    1978-01-01

    The effects of the nozzle wall boundary layer on the plume flowfield are neglected in the majority of computational schemes which exist for the calculation of rocket engine exhaust plume flowfields. This neglect, which is unimportant in many applications, becomes unacceptable for applications where a surface which can be adversely affected by plume impingement forces, heating, or contamination is located behind the nozzle exit plane in what is called the 'plume backflow region'. The flow in this region originates in, and is highly affected by, the nozzle wall boundary layer. The inclusion of the effects of the boundary layer in the calculations is required for an appropriate determination of the flowfield properties within this region. A description is presented of the results of modifications of a method-of-characteristics computer program. The modifications were made to include the effects of the nozzle wall boundary layer on the plume flowfield. A comparison of computed and experimental data indicates that the employed computer program may be a useful tool for calculating the entire plume flowfield for liquid propellant rocket engines.

  1. On the mechanism of atmospheric pressure plasma plume

    Science.gov (United States)

    Chen, Longwei; Zhao, Peng; Shu, Xingsheng; Shen, Jie; Meng, Yuedong

    2010-08-01

    For the purpose of unveiling the parameters influencing the length of atmospheric pressure plasma plume, an over 165 cm long argon plasma plume is generated in the quartz tube attached to the nozzle of the device. Dependence of plasma length on discharge parameters such as applied voltage, frequency of power supply, and argon gas flow rate was investigated. Experimental results indicated that (a) the applied voltage plays crucial roles on plasma plume length, that is, the plasma plume length exponentially increases with the applied voltage, (b) the plasma plume length increases with frequency, more obviously when the applied voltage is higher, (c) the plasma plume length increases with argon gas flow rate, reaches its maximum at critical value of the gas flow rate, and then decreases again. An evaluation of the physical phenomena involved in streamer propagation, particularly of the energy balance, was investigated. The numerical results were qualitatively consistent with previous experimental results by successfully indicating the high velocity of "plasma bullet" and providing physical mechanism of energy balance determining streamer length.

  2. A Preliminary Model of Infrared Image Generation for Exhaust Plume

    Directory of Open Access Journals (Sweden)

    Fei Mei

    2011-06-01

    Full Text Available Based on the irradiance calculation of all pixels on the focal plane array, a preliminary infrared imaging prediction model of exhaust plume that have considered the geometrical and the thermal resolution of the camera was developed to understanding the infrared characteristics of exhaust plume. In order to compute the irradiance incident on each pixel, the gas radiation transfer path in the plume for the instantaneous field of view corresponds to the pixel was solved by the simultaneous equation of a enclosure cylinder which covers the exhaust plume and the line of sight. Radiance of the transfer path was calculated by radiation transfer equation for nonscattering gas. The radiative properties of combustion needed in the equation was provided by employing Malkmus model with EM2C narrow band database(25cm-1. The pressure, species concentration along the path was determination by CFD analysis. The relative irradiance intensity of each pixel was converted to color in the display according to gray map coding and hot map coding. Infrared image of the exhaust plumes from a subsonic axisymmetric nozzle with different relative position of camera and the plume was predicted with the model. By changing the parameters, such as FOV and space resolution, the image of different imaging system can be predicted.

  3. Implementation of microwave transmissions for rocket exhaust plume diagnostics

    Science.gov (United States)

    Coutu, Nicholas George

    Rocket-launched vehicles produce a trail of exhaust that contains ions, free electrons, and soot. The exhaust plume increases the effective conductor length of the rocket. A conductor in the presence of an electric field (e.g. near the electric charge stored within a cloud) can channel an electric discharge. The electrical conductivity of the exhaust plume is related to its concentration of free electrons. The risk of a lightning strike in-flight is a function of both the conductivity of the body and its effective length. This paper presents an approach that relates the electron number density of the exhaust plume to its propagation constant. Estimated values of the collision frequency and electron number density generated from a numerical simulation of a rocket plume are used to guide the design of the experimental apparatus. Test par meters are identified for the apparatus designed to transmit a signal sweep form 4 GHz to 7 GHz through the exhaust plume of a J-class solid rocket motor. Measurements of the scattering parameters imply that the transmission does not penetrate the plume, but instead diffracts around it. The electron density 20 cm downstream from the nozzle exit is estimated to be between 2.7x1014 m--3 and 5.6x10 15 m--3.

  4. Updated Conceptual Model for the 300 Area Uranium Groundwater Plume

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, John M.; Freshley, Mark D.; Last, George V.; Peterson, Robert E.; Bjornstad, Bruce N.

    2012-11-01

    The 300 Area uranium groundwater plume in the 300-FF-5 Operable Unit is residual from past discharge of nuclear fuel fabrication wastes to a number of liquid (and solid) disposal sites. The source zones in the disposal sites were remediated by excavation and backfilled to grade, but sorbed uranium remains in deeper, unexcavated vadose zone sediments. In spite of source term removal, the groundwater plume has shown remarkable persistence, with concentrations exceeding the drinking water standard over an area of approximately 1 km2. The plume resides within a coupled vadose zone, groundwater, river zone system of immense complexity and scale. Interactions between geologic structure, the hydrologic system driven by the Columbia River, groundwater-river exchange points, and the geochemistry of uranium contribute to persistence of the plume. The U.S. Department of Energy (DOE) recently completed a Remedial Investigation/Feasibility Study (RI/FS) to document characterization of the 300 Area uranium plume and plan for beginning to implement proposed remedial actions. As part of the RI/FS document, a conceptual model was developed that integrates knowledge of the hydrogeologic and geochemical properties of the 300 Area and controlling processes to yield an understanding of how the system behaves and the variables that control it. Recent results from the Hanford Integrated Field Research Challenge site and the Subsurface Biogeochemistry Scientific Focus Area Project funded by the DOE Office of Science were used to update the conceptual model and provide an assessment of key factors controlling plume persistence.

  5. P and S wave delays caused by thermal plumes

    Science.gov (United States)

    Maguire, Ross; Ritsema, Jeroen; van Keken, Peter E.; Fichtner, Andreas; Goes, Saskia

    2016-05-01

    Many studies have sought to seismically image plumes rising from the deep mantle in order to settle the debate about their presence and role in mantle dynamics, yet the predicted seismic signature of realistic plumes remains poorly understood. By combining numerical simulations of flow, mineral-physics constraints on the relationships between thermal anomalies and wave speeds, and spectral-element method based computations of seismograms, we estimate the delay times of teleseismic S and P waves caused by thermal plumes. Wavefront healing is incomplete for seismic periods ranging from 10 s (relevant in traveltime tomography) to 40 s (relevant in waveform tomography). We estimate P wave delays to be immeasurably small ( 20 s), measurements of instantaneous phase misfit may be more useful in resolving narrow plume conduits. To detect S wave delays of 0.4-0.8 s and the diagnostic frequency dependence imparted by plumes, it is key to minimize the influence of the heterogeneous crust and upper mantle. We argue that seismic imaging of plumes will advance significantly if data from wide-aperture ocean-bottom networks were available since, compared to continents, the oceanic crust and upper mantle is relatively simple.

  6. Model Selection Coupled with a Particle Tracking Proxy Using Surface Deformation Data for Monitoring CO2 Plume Migration

    Science.gov (United States)

    Min, B.; Nwachukwu, A.; Srinivasan, S.; Wheeler, M. F.

    2015-12-01

    This study formulates a framework of a model selection that refines geological models for monitoring CO2 plume migration. Special emphasis is placed on CO2 injection, and the particular techniques that are used for this study including model selection, particle tracking proxies, and partial coupling of flow and geomechanics. The proposed process starts with generating a large initial ensemble of reservoir models that reflect a prior uncertainty in reservoir description, including all plausible geologic scenarios. These models are presumed to be conditioned to available static data. In the absence of production or injection data, all prior reservoir models are regarded as equiprobable. Thus, the model selection algorithm is applied to select a few representative reservoir models that are more consistent with observed dynamic responses. A quick assessment of the models must then be performed to evaluate their dynamic characteristics and flow connectivity. This approach develops a particle tracking proxy and a finite element method solver for solving the flow equation and the stress problem, respectively. The shape of CO2 plume is estimated using a particle-tracking proxy that serves as a fast approximation of finite-difference simulation models. Sequentially, a finite element method solver is coupled with the proxy for analyzing geomechanical effects resulting from CO2 injection. A method is then implemented to group the models into clusters based on similarities in the estimated responses. The posterior model set is chosen as the cluster that produces the minimum deviation from the observed field data. The efficacy of non-dominated sorting based on Pareto-optimality is also tested in the current model selection framework. The proposed scheme is demonstrated on a carbon sequestration project in Algeria. Coupling surface deformation data with well injection data enhances the efficiency of tracking the CO2 plume. Therefore, this algorithm provides a probabilistic

  7. Cluster editing

    DEFF Research Database (Denmark)

    Böcker, S.; Baumbach, Jan

    2013-01-01

    . The problem has been the inspiration for numerous algorithms in bioinformatics, aiming at clustering entities such as genes, proteins, phenotypes, or patients. In this paper, we review exact and heuristic methods that have been proposed for the Cluster Editing problem, and also applications......The Cluster Editing problem asks to transform a graph into a disjoint union of cliques using a minimum number of edge modifications. Although the problem has been proven NP-complete several times, it has nevertheless attracted much research both from the theoretical and the applied side...

  8. Weighted Clustering

    CERN Document Server

    Ackerman, Margareta; Branzei, Simina; Loker, David

    2011-01-01

    In this paper we investigate clustering in the weighted setting, in which every data point is assigned a real valued weight. We conduct a theoretical analysis on the influence of weighted data on standard clustering algorithms in each of the partitional and hierarchical settings, characterising the precise conditions under which such algorithms react to weights, and classifying clustering methods into three broad categories: weight-responsive, weight-considering, and weight-robust. Our analysis raises several interesting questions and can be directly mapped to the classical unweighted setting.

  9. Cluster analysis

    CERN Document Server

    Everitt, Brian S; Leese, Morven; Stahl, Daniel

    2011-01-01

    Cluster analysis comprises a range of methods for classifying multivariate data into subgroups. By organizing multivariate data into such subgroups, clustering can help reveal the characteristics of any structure or patterns present. These techniques have proven useful in a wide range of areas such as medicine, psychology, market research and bioinformatics.This fifth edition of the highly successful Cluster Analysis includes coverage of the latest developments in the field and a new chapter dealing with finite mixture models for structured data.Real life examples are used throughout to demons

  10. Clustered impacts - Experiments and implications. [cratering mechanics

    Science.gov (United States)

    Schultz, P. H.; Gault, D. E.

    1985-01-01

    The characteristics of impact by clusters of projectiles are experimentally studied by launching grouped projectiles of aluminum shot, steel shot, iron filings, and sand. Cratering efficiency is considered as a function of a dimensionless parameter related to projectile size and impact velocity. The effects of different target and projectile densities on cratering efficiency are examined. Crater morphology is addressed by considering a typical example, reviewing the systematics between cluster dispersion and crater morphology for vertical impacts, and examining oblique angle impacts which have relevance for planetary secondary cratering processes. These results are compared with impacts by single bodies with different strengths. The evolution of the ejecta plume for clustered impacts is compared to that for single-body impacts for vertical and oblique impacts from 1.3 to 1.8 km/s. The experimental results are discussed in the context of planetary surface processes, emphasizing processes in an atmosphere-free environment and secondary impact cratering.

  11. Fuzzy Clustering

    DEFF Research Database (Denmark)

    Berks, G.; Keyserlingk, Diedrich Graf von; Jantzen, Jan

    2000-01-01

    A symptom is a condition indicating the presence of a disease, especially, when regarded as an aid in diagnosis.Symptoms are the smallest units indicating the existence of a disease. A syndrome on the other hand is an aggregate, set or cluster of concurrent symptoms which together indicate...... and clustering are the basic concerns in medicine. Classification depends on definitions of the classes and their required degree of participant of the elements in the cases' symptoms. In medicine imprecise conditions are the rule and therefore fuzzy methods are much more suitable than crisp ones. Fuzzy c......-mean clustering is an easy and well improved tool, which has been applied in many medical fields. We used c-mean fuzzy clustering after feature extraction from an aphasia database. Factor analysis was applied on a correlation matrix of 26 symptoms of language disorders and led to five factors. The factors...

  12. Evidence for melt channelization in Galapagos plume-ridge interaction

    Science.gov (United States)

    Mittal, T.; Richards, M. A.

    2015-12-01

    Many present-day hot spots are located within ~ 1000 km of a mid-ocean ridge, either currently or in the geologic past, leading to frequent interaction between these two magmatic regimes. The consequent plume-ridge interactions provide a unique opportunity to test models for asthenosphere-lithosphere dynamics, with the plume acting as a tracer fluid in the problem, and excess magmatism reflecting otherwise unsampled sub-surface phenomena. Galapagos is an off-ridge hotspot with the mantle plume located ~150-250 km south of the plate boundary. Plume-ridge interaction in Galapagos is expressed by the formation of volcanic lineaments of islands and seamounts - e.g., the Wolf-Darwin lineament (WDL) - providing a direct probe of the plume-ridge interaction process, especially in regards to geochemical data. Although several models have been proposed to explain plume-ridge interaction in Galapagos, none adequately explain the observed characteristics, especially the WDL. In particular, predicted lithospheric fault orientations and melt density considerations appear at odds with observations, suggesting that lithospheric extension is not the primary process for formation of these islands. Other off-ridge hotspots interacting with nearby spreading ridges, such as Reunion and Louisville, also exhibit volcanic lineaments linking the plume and the ridge. Thus these lineament-type features are a common outcome of plume-ridge interaction that are indicative of the underlying physics. We propose that the lineaments are surface expressions of narrow sub-lithospheric melt channels focused towards the spreading ridge. These channels should form naturally due to the reactive infiltration instability in a two-phase flow of magma and solid mantle as demonstrated in two-phase flow simulations (e.g., Katz & Weatherley 2012). For Galapagos, we show that melt channels can persist thermodynamically over sufficient length-scales to link the plume and nearby ridge segments. We also show that

  13. Hydrothermal plume anomalies along the Central Indian Ridge

    Institute of Scientific and Technical Information of China (English)

    ZHU Jian; LIN Jian; GUO ShiQin; CHEN YongShun

    2008-01-01

    Water column turbidity and temperature were investigated along the Central Indian Ridge (CIR) from 25°19'S to 23°48'S during a December 2005 cruise on board Chinese P/V DayangYihao.Measurements were made using NOAA's MAPR (Miniature Autonomous Plume Recorder) sensors during CTD casts,TV grabber operations,and tow-yo profiles,yielding the following results on hydrothermal plume anomalies:(1) Strong hydrothermal turbidity and temperature anomalies were recorded over the pre-viously discovered Kairei (25°19.2'S,70°02.4'E) and Edmond (23°52.7'S,69°35.8"E) vent fields,with the plume anomalies concentrated at depths of 2150-2300 m and 2700-2900 m,respectively.The maxi-mum height of the turbidity anomalies near the Kairei vent field recorded in December 2005 was slightly below 2100 m,which is consistent with the plume depth measured in June 2001,indicating that the Kairei plume may have maintained its buoyancy flux in the intervening 4.5 years.(2) The water column beneath the Kairei plume has background anomalies of about 0.005△NTU,whereas no such back-ground turbidity anomalies were observed below the Edmond hydrothermal plume.(3) No visible tur-bidity anomalies were detected from 24°42'S to 24°12'S including the Knorr Seamount.Thus 24°12'S marks the southern end of the hydrothermal plume.(4) Significant turbidity anomalies were observed at four individual sections from 24°12'S to 23°56'S at the depth of 2500-3000 m along the eastern rift valley wall.Whether the individual sections of anomalies are connected is still unknown due to the absence of data at the intervening gaps.If the four sections are connected with each other and are linked to the Edmond vent field farther to the north,the total along-axis length of the plume anomaly would be more than 37 km,implying a plume incidence value Ph of 0.38,greater than the predicted Ph of 0.21-0.25 based on the spreading rate of the Central Indian Ridge.

  14. Studies of the Kuwait oil fire plume during midsummer 1991

    Science.gov (United States)

    Daum, P. H.; Al-Sunaid, A.; Busness, K. M.; Hales, J. M.; Mazurek, M.

    1993-01-01

    This paper reports aircraft observations of the Kuwait oil fire plume conducted during the period July 31-August 17, 1991. During this study the plume was transported almost exclusively to the south of Kuwait over the Persian Gulf and the Arabian Peninsula. The plume base was generally found to be well above the surface, in some cases as high as 1-2 km; plume tops did not exceed 5 km. Aerosol mass (based on measured aerosol constituents) in the central section of the plume, ca. 150-200 km downwind of the source region, was found to be >500 μg/m3, with number densities in the size range (approximate) 0.2 carbon, and organic carbon. Sodium chloride constituted a surprisingly large component of the soluble inorganic mass. The aerosol particles appeared to function as good cloud condensation nuclei, with a large fraction of accumulation mode particles (by number) activated at a supersaturation of 0.6%. Under conditions in which the plume was relatively compact, transmittance of solar radiation to the surface was only 10-20%. Plume albedo was observed to be as low as 2-3% close to the source region, consistent with the high elemental-carbon concentrations present in the plume. Trace gas concentrations were consistent with fuel composition and with current knowledge of atmospheric chemical processes. Sulfur dioxide concentrations close to the source region were found to be as high as 300-400 ppb. The emissions factor for S (expressed as a percentage) was estimated to be 1.8%, which is consistent with estimates of a fuel sulfur content of 2-2.5%. SO2 was found to be only slowly oxidized (<1%/h). Nitrogen oxide concentrations were found to be quite low (<50 ppb near the source, decreasing to 1-2 ppb well downwind), which is consistent with a crude oil nitrogen source. Despite relatively low concentrations, sufficient NOx was present to act as a catalyst to generate excess ozone in the plume as the plume was transported downwind and dispersed.

  15. Coordinated sensor cueing for chemical plume detection

    Science.gov (United States)

    Abraham, Nathan J.; Jensenius, Andrea M.; Watkins, Adam S.; Hawthorne, R. Chad; Stepnitz, Brian J.

    2011-05-01

    This paper describes an organic data fusion and sensor cueing approach for Chemical, Biological, Radiological, and Nuclear (CBRN) sensors. The Joint Warning and Reporting Network (JWARN) uses a hardware component referred to as the JWARN Component Interface Device (JCID). The Edgewood Chemical and Biological Center has developed a small footprint and open architecture solution for the JCID capability called JCID-on-a-Chip (JoaC). The JoaC program aims to reduce the cost and complexity of the JCID by shrinking the necessary functionality down to a small single board computer. This effort focused on development of a fusion and cueing algorithm organic to the JoaC hardware. By embedding this capability in the JoaC, sensors have the ability to receive and process cues from other sensors without the use of a complex and costly centralized infrastructure. Additionally, the JoaC software is hardware agnostic, as evidenced by its drop-in inclusion in two different system-on-a-chip platforms including Windows CE and LINUX environments. In this effort, a partnership between JPM-CA, JHU/APL, and the Edgewood Chemical and Biological Center (ECBC), the authors implemented and demonstrated a new algorithm for cooperative detection and localization of a chemical agent plume. This experiment used a pair of mobile Joint Services Lightweight Standoff Chemical Agent Detector (JSLSCAD) units which were controlled by fusion and cueing algorithms hosted on a JoaC. The algorithms embedded in the JoaC enabled the two sensor systems to perform cross cueing and cooperatively form a higher fidelity estimate of chemical releases by combining sensor readings. Additionally, each JSLSCAD had the ability to focus its search on smaller regions than those required by a single sensor system by using the cross cue information from the other sensor.

  16. Constraining the Enceladus plume using numerical simulation and Cassini data

    Science.gov (United States)

    Yeoh, Seng Keat; Li, Zheng; Goldstein, David B.; Varghese, Philip L.; Levin, Deborah A.; Trafton, Laurence M.

    2017-01-01

    Since its discovery, the Enceladus plume has been subjected to intense study due to the major effects that it has on the Saturnian system and the window that it provides into the interior of Enceladus. However, several questions remain and we attempt to answer some of them in this work. In particular, we aim to constrain the H2O production rate from the plume, evaluate the relative importance of the jets and the distributed sources along the Tiger Stripes, and make inferences about the source of the plume by accurately modeling the plume and constraining the model using the Cassini INMS and UVIS data. This is an extension of a previous work (Yeoh, S.K., et al. [2015] Icarus, 253, 205-222) in which we only modeled the collisional part of the Enceladus plume and studied its important physical processes. In this work, we propagate the plume farther into space where the flow has become free-molecular and the Cassini INMS and UVIS data were sampled. Then, we fit this part of the plume to the INMS H2O density distributions sampled along the E3, E5 and E7 trajectories and also compare some of the fit results with the UVIS measurements of the plume optical depth collected during the solar occultation observation on 18 May 2010. We consider several vent conditions and source configurations for the plume. By constraining our model using the INMS and UVIS data, we estimate H2O production rates of several hundred kgs-1: 400-500 kg/s during the E3 and E7 flybys and ∼900 kg/s during the E5 flyby. These values agree with other estimates and are consistent with the observed temporal variability of the plume over the orbital period of Enceladus (Hedman, M.M., et al. [2013] Nature, 500, 182-184). In addition, we determine that one of the Tiger Stripes, Cairo, exhibits a local temporal variability consistent with the observed overall temporal variability of the plume. We also find that the distributed sources along the Tiger Stripes are likely dominant while the jets provide a

  17. Enceladus Plume Structure and Time Variability: Comparison of Cassini Observations.

    Science.gov (United States)

    Teolis, Ben D; Perry, Mark E; Hansen, Candice J; Waite, J Hunter; Porco, Carolyn C; Spencer, John R; Howett, Carly J A

    2017-09-05

    During three low-altitude (99, 66, 66 km) flybys through the Enceladus' plume in 2010 and 2011, Cassini's ion neutral mass spectrometer (INMS) made its first high spatial resolution measurements of the plume's gas density and distribution, detecting in situ the individual gas jets within the broad plume. Since those flybys, more detailed Imaging Science Subsystem (ISS) imaging observations of the plume's icy component have been reported, which constrain the locations and orientations of the numerous gas/grain jets. In the present study, we used these ISS imaging results, together with ultraviolet imaging spectrograph stellar and solar occultation measurements and modeling of the three-dimensional structure of the vapor cloud, to constrain the magnitudes, velocities, and time variability of the plume gas sources from the INMS data. Our results confirm a mixture of both low and high Mach gas emission from Enceladus' surface tiger stripes, with gas accelerated as fast as Mach 10 before escaping the surface. The vapor source fluxes and jet intensities/densities vary dramatically and stochastically, up to a factor 10, both spatially along the tiger stripes, and over time between flyby observations. This complex spatial variability and dynamics may result from time-variable tidal stress fields interacting with subsurface fissure geometry and tortuosity beyond detectability, including changing gas pathways to the surface, and fluid flow and boiling in response evolving lithostatic stress conditions. The total plume gas source has 30% uncertainty depending on the contributions assumed for adiabatic and nonadiabatic gas expansion/acceleration to the high Mach emission. The overall vapor plume source rate exhibits stochastic time variability up to a factor ∼5 between observations, reflecting that found in the individual gas sources/jets. Key Words: Cassini at saturn-Geysers-Enceladus-Gas dynamics-Icy satellites. Astrobiology 17, xxx-xxx.

  18. Hydrogeophysical investigations of the former S-3 ponds contaminant plumes

    Energy Technology Data Exchange (ETDEWEB)

    Revil, Andre [ORNL; Skold, Magnus E [ORNL; Karaoulis, Marios [Colorado School of Mines, Golden; Schmutz, Myriam [Institut Polytechnique de Bordeaux; Hubbard, Susan S [Lawrence Berkeley National Laboratory (LBNL); Mehlhorn, Tonia L [ORNL; Watson, David B [ORNL

    2013-01-01

    At the Oak Ridge Integrated Field Research Challenge site, near Oak Ridge, Tennessee, contaminants from the former S-3 ponds have infiltrated the shallow saprolite for over 60 years. Two- and three-dimensional DC-resistivity tomography is used to characterize the number and location of the main contaminant plumes, which include high concentration of nitrate. These contaminant plumes have typically an electrical resistivity in the range 2 20 ohm-m while the background saprolite resistivity is in the range 60 120 ohm-m, so the difference of resistivity can be easily mapped using DC-resistivity tomography to locate the contaminant pathways. We develop a relationship to derive the in situ nitrate concentrations from the 3D resistivity tomograms accounting for the effect of surface conductivity. The footprint of the contamination upon the resistivity is found to be much stronger than the local variations associated with changes in the porosity and the clay content. With this method, we identified a total of five main plumes (termed CP1 to CP5). Plume CP2 corresponds to the main plume in terms of nitrate concentration ( 50,000 ). We also used an active time constrained approach to perform time-lapse resistivity tomography over a section crossing the plumes CP1 and CP2. The sequence of tomograms is used to determine the changes in the nitrate concentrations associated with infiltration of fresh (meteoritic) water from a perched aquifer. This study highlights the importance of accounting for surface conductivity when characterizing plume distributions in clay-rich subsurface systems.

  19. Two cases of atmospheric escape in the Solar System: Titan and Earth

    Science.gov (United States)

    Dandouras, I.

    2012-01-01

    Escape into space of the constituents of a planetary upper atmosphere can occur either in the form of neutral gas (thermal escape or non-thermal escape), or in the form of plasma. The long-term stability of an atmosphere results from the balance between source and escape rates. Two cases will be examined: Titan and Earth. Titan is the second largest planetary satellite in the Solar System and is the only one that has an atmosphere as substantial as that of the Earth. Titan's nitrogen rich atmosphere is embedded within Saturn's magnetosphere, and is directly bombarded by energetic ions due to Titan's lack of a significant intrinsic magnetic field. In addition to thermal escape, energy input from Saturn's magnetosphere and from Solar UV radiation can drive several non-thermal escape mechanisms in Titan's upper atmosphere: sputtering, dissociation and dissociative ionization of molecular nitrogen producing pick-up ions, photochemical production of fast neutrals etc. Earth also constantly loses matter, mostly in the form of H+ and O+ ions, through various outflow processes from the upper atmosphere and ionosphere. Most of the ions are low-energy (plasma reservoir is the plasmasphere, which is a toroidal region encircling the Earth and containing cold and dense plasma. Plasma plumes, forming in the outer plasmasphere and released outwards, constitute a well-established mode for plasmaspheric material release to the magnetosphere. They are associated to geomagnetically active periods and the related electric field change. In 1992 Lemaire and Shunk proposed the existence of an additional mode for plasmaspheric material release and escape: a plasmaspheric wind, steadily transporting cold plasmaspheric plasma outwards across the geomagnetic field lines. This has been proposed on a theoretical basis. Direct detection of this wind has, however, eluded observation in the past. Analysis of ion measurements, acquired in the outer plasmasphere by the CIS experiment onboard the

  20. Near-field entrainment in black smoker plumes

    Science.gov (United States)

    Smith, J. E.; Germanovich, L. N.; Lowell, R. P.

    2013-12-01

    In this work, we study the entrainment rate of the ambient fluid into a plume in the extreme conditions of hydrothermal venting at ocean floor depths that would be difficult to reproduce in the laboratory. Specifically, we investigate the flow regime in the lower parts of three black smoker plumes in the Main Endeavour Field on the Juan de Fuca Ridge discharging at temperatures of 249°C, 333°C, and 336°C and a pressure of 21 MPa. Such flow conditions are typical for ocean floor hydrothermal venting but would be difficult to reproduce in the laboratory. The centerline temperature was measured at several heights in the plume above the orifice. Using a previously developed turbine flow meter, we also measured the mean flow velocity at the orifice. Measurements were conducted during dives 4452 and 4518 on the submersible Alvin. Using these measurements, we obtained a range of 0.064 - 0.068 for values of the entrainment coefficient α, which is assumed constant near the orifice. This is half the value of α ≈ 0.12 - 0.13 that would be expected for plume flow regimes based on the existing laboratory results and field measurements in lower temperature and pressure conditions. In fact, α = 0.064 - 0.068 is even smaller than the value of α ≈ 0.075 characteristic of jet flow regimes and appears to be the lowest reported in the literature. Assuming that the mean value α = 0.066 is typical for hydrothermal venting at ocean floor depths, we then characterized the flow regimes of 63 black smoker plumes located on the Endeavor Segment of the Juan de Fuca Ridge. Work with the obtained data is ongoing, but current results indicate that approximately half of these black smokers are lazy in the sense that their plumes exhibit momentum deficits compared to the pure plume flow that develops as the plume rises. The remaining half produces forced plumes that show the momentum excess compared to the pure plumes. The lower value of the entrainment coefficient has important

  1. AATSR Based Volcanic Ash Plume Top Height Estimation

    Science.gov (United States)

    Virtanen, Timo H.; Kolmonen, Pekka; Sogacheva, Larisa; Sundstrom, Anu-Maija; Rodriguez, Edith; de Leeuw, Gerrit

    2015-11-01

    The AATSR Correlation Method (ACM) height estimation algorithm is presented. The algorithm uses Advanced Along Track Scanning Radiometer (AATSR) satellite data to detect volcanic ash plumes and to estimate the plume top height. The height estimate is based on the stereo-viewing capability of the AATSR instrument, which allows to determine the parallax between the satellite's nadir and 55◦ forward views, and thus the corresponding height. AATSR provides an advantage compared to other stereo-view satellite instruments: with AATSR it is possible to detect ash plumes using brightness temperature difference between thermal infrared (TIR) channels centered at 11 and 12 μm. The automatic ash detection makes the algorithm efficient in processing large quantities of data: the height estimate is calculated only for the ash-flagged pixels. Besides ash plumes, the algorithm can be applied to any elevated feature with sufficient contrast to the background, such as smoke and dust plumes and clouds. The ACM algorithm can be applied to the Sea and Land Surface Temperature Radiometer (SLSTR), scheduled for launch at the end of 2015.

  2. Sewage outfall plume dispersion observations with an autonomous underwater vehicle.

    Science.gov (United States)

    Ramos, P; Cunha, S R; Neves, M V; Pereira, F L; Quintaneiro, I

    2005-01-01

    This work represents one of the first successful applications of Autonomous Underwater Vehicles (AUVs) for interdisciplinary coastal research. A monitoring mission to study the shape and estimate the initial dilution of the S. Jacinto sewage outfall plume using an AUV was performed on July 2002. An efficient sampling strategy enabling greater improvements in spatial and temporal range of detection demonstrated that the sewage effluent plume can be clearly traced using naturally occurring tracers in the wastewater. The outfall plume was found at the surface highly influenced by the weak stratification and low currents. Dilution varying with distance downstream was estimated from the plume rise over the outfall diffuser until a nearly constant value of 130:1, 60 m from the diffuser, indicating the near field end. Our results demonstrate that AUVs can provide high-quality measurements of physical properties of effluent plumes in a very effective manner and valuable considerations about the initial mixing processes under real oceanic conditions can be further investigated.

  3. A cold plasma plume with a highly conductive liquid electrode

    Institute of Scientific and Technical Information of China (English)

    Chen Guang-Liang; Chen Shi-gua; Chen Wen-Xing; Yang Si-Ze

    2008-01-01

    A cold dielectric barrier discharge (DBD) plasma plume with one highly conductive liquid electrode has been developed to treat thermally sensitive materials, and its preliminary discharging characteristics have been studied. The averaged electron temperature and density is estimated to be 0.6eV and 1011/cm3, respectively. The length of plasma plume can reach 5cm with helium gas (He), and the conductivity of the outer electrode affects the plume length obviously. This plasma plume could be touched by bare hand without causing any burning or painful sensation,which may provide potential application for safe aseptic skin care. Moreover, the oxidative particles (e.g., OH, O*03) in the downstream oxygen (02) gas of the plume have been applied to treat the landfill leachate. The results show that the activated 02 gas can degrade the landfill leachate effectively, and the chemical oxygen demand (COD),conductivity, biochemical oxygen demand (BOD), and suspended solid (SS) can be decreased by 52%, 57%, 76% and 92%, respectively.

  4. Solar coronal plumes and the fast solar wind

    CERN Document Server

    Dwivedi, B N

    2015-01-01

    The spectral profiles of the coronal Ne viii line at 77 nm have different shapes in quiet-Sun regions and coronal holes (CHs). A single Gaussian fit of the line profile provides an adequate approximation in quiet-Sun areas, whereas a strong shoulder on the long-wavelength side is a systematic feature in CHs. Although this has been noticed since 1999, no physical reason for the peculiar shape could be given. In an attempt to identify the cause of this peculiarity, we address three problems that could not be conclusively resolved in a review article by a study team of the International Space Science Institute (ISSI; Wilhelm et al. 2011) : (1) The physical processes operating at the base and inside of plumes as well as their interaction with the solar wind (SW). (2) The possible contribution of plume plasma to the fast SW streams. (3) The signature of the first-ionization potential (FIP) effect between plumes and inter-plume regions (IPRs). Before the spectroscopic peculiarities in IPRs and plumes in polar coron...

  5. Estimation of Enceladus Plume Density Using Cassini Flight Data

    Science.gov (United States)

    Wang, Eric K.; Lee, Allan Y.

    2011-01-01

    The Cassini spacecraft was launched on October 15, 1997 by a Titan 4B launch vehicle. After an interplanetary cruise of almost seven years, it arrived at Saturn on June 30, 2004. In 2005, Cassini completed three flybys of Enceladus, a small, icy satellite of Saturn. Observations made during these flybys confirmed the existence of water vapor plumes in the south polar region of Enceladus. Five additional low-altitude flybys of Enceladus were successfully executed in 2008-9 to better characterize these watery plumes. During some of these Enceladus flybys, the spacecraft attitude was controlled by a set of three reaction wheels. When the disturbance torque imparted on the spacecraft was predicted to exceed the control authority of the reaction wheels, thrusters were used to control the spacecraft attitude. Using telemetry data of reaction wheel rates or thruster on-times collected from four low-altitude Enceladus flybys (in 2008-10), one can reconstruct the time histories of the Enceladus plume jet density. The 1 sigma uncertainty of the estimated density is 5.9-6.7% (depending on the density estimation methodology employed). These plume density estimates could be used to confirm measurements made by other onboard science instruments and to support the modeling of Enceladus plume jets.

  6. Pyroxenite in the Galapagos plume source at 65 Ma

    Science.gov (United States)

    Whalen, W. T.; Gazel, E.; Vidito, C. A.; Herzberg, C. T.; Class, C.; Bizimis, M.; Alvarado-Induni, G.

    2013-12-01

    Mantle plumes originate from boundary layers below the upper mantle. Their surface expressions as hotspot tracks have been linked to voluminous outpourings of lava in the form of large igneous provinces. The Galapagos hotspot has been active since ~90 Ma and the oldest lavas of its associated submarine ridge have been dated to ~14 Ma, subducting at the Middle America Trench, off Costa Rica. The Galapagos plume head magmatic production is preserved as the Caribbean Large Igneous Province (CLIP). A series of 15-65 Ma accreted Galapagos paleo-ridges and islands/seamounts are accreted in the Pacific coast of Costa Rica and Panama. One of these accreted terranes, the Quepos block on the west coast of Costa Rica is an ancient, ~65 Ma Galapagos island. Olivine phenocrysts from Quepos picrites have elevated Ni and low Ca and Mn and Fe/Mn indicative of a dominant pyroxenite source component while CLIP samples are dominated by a peridotite source. The mantle potential temperature (max) of the plume changed from ~1650 to ~1550 C at 65 Ma. This change correlates with the first appearance of the pyroxenite component and an EMII signature (Northern Galapagos Domain) in the Galapagos plume. A relatively dense pyroxenite component may provide a mechanism for the change in Tp due to its effect on the plume's bouyancy. Alternatively, the pyroxenite component was diluted by high peridotite melt fraction during the massive production of the CLIP.

  7. Effects of Boundary Conditions on Near Field Plasma Plume Simulations

    Science.gov (United States)

    Boyd, Iain

    2004-11-01

    The successful development of various types of electric propulsion devices is providing the need for accurate assessment of integration effects generated by the interaction of the plasma plumes of these thrusters with the host spacecraft. Assessment of spacecraft interaction effects in ground based laboratory facilities is inadequate due to the technical difficulties involved in accurately recreating the near vacuum ambient conditions experienced in space. This situation therefore places a heavy demand on computational modeling of plasma plume phenomena. Recently (Boyd and Yim, Journal of Applied Physics, Vol. 95, 2004, pp. 4575-5484) a hybrid model of the near field of the plume of a Hall thruster was reported in which the heavy species are modeled using particles and the electrons are modeled using a detailed fluid description. The present study continues the model development and assessment by considering the sensitivity of computed results to different types of boundary conditions that must be formulated for the thruster exit, for the cathode exit, for the thruster walls, and for the plume far field. The model is assessed through comparison of its predictions with several sets of experimental data measured in the plume of the BHT-200 Hall thruster.

  8. Calculating the probability of injected carbon dioxide plumes encountering faults

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, P.D.

    2011-04-01

    One of the main concerns of storage in saline aquifers is leakage via faults. In the early stages of site selection, site-specific fault coverages are often not available for these aquifers. This necessitates a method using available fault data to estimate the probability of injected carbon dioxide encountering and migrating up a fault. The probability of encounter can be calculated from areal fault density statistics from available data, and carbon dioxide plume dimensions from numerical simulation. Given a number of assumptions, the dimension of the plume perpendicular to a fault times the areal density of faults with offsets greater than some threshold of interest provides probability of the plume encountering such a fault. Application of this result to a previously planned large-scale pilot injection in the southern portion of the San Joaquin Basin yielded a 3% and 7% chance of the plume encountering a fully and half seal offsetting fault, respectively. Subsequently available data indicated a half seal-offsetting fault at a distance from the injection well that implied a 20% probability of encounter for a plume sufficiently large to reach it.

  9. Bipropellant rocket exhaust plume analysis on the Galileo spacecraft

    Science.gov (United States)

    Guernsey, C. S.; Mcgregor, R. D.

    1986-01-01

    This paper describes efforts to quantify the contaminant flow field produced by 10 N thrust bipropellant rocket engines used on the Galileo spacecraft. The prediction of the composition of the rocket exhaust by conventional techniques is found to be inadequate to explain experimental observations of contaminant deposition on moderately cold (200 K) surfaces. It is hypothesized that low volatility contaminants are formed by chemical reactions which occur on the surfaces. The flow field calculations performed using the direct simulation Monte Carlo method give the expected result that the use of line-of-sight plume shields may have very little effect on the flux of vapor phase contaminant species to a surface, especially if the plume shields are located so close to the engine that the interaction of the plume with the shield is in the transition flow regime. It is shown that significant variations in the exhaust plume composition caused by nonequilibrium effects in the flow field lead to very low concentrations of species which have high molecular weights in the more rarefied regions of the flow field. Recommendations for the design of spacecraft plume shields and further work are made.

  10. Gaseous plume flows in space propulsion

    Institute of Scientific and Technical Information of China (English)

    Wang Limei; Cai Chunpei

    2013-01-01

    This paper presents a gaskinetic study on high-speed,highly rarefied jets expanding into a vacuum from a cluster of planar or annular exits.Based on the corresponding exact expressions for a planar or annular jet,it is convenient to derive the combined multiple jet flowfield solutions of density and velocity components.For the combined temperature and pressure solutions,extra attention is needed.Several direct simulation Monte Carlo simulation results are provided to validate these analytical solutions.The analytical and numerical solutions are essentially identical for these high Knudsen number jet flows.

  11. Cluster forcing

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    .g. sustainability or quality of life. The purpose of this paper is to explore how and to what extent public sector interventions that aim at forcing cluster development in industries can support sustainable development as defined in the Brundtland tradition and more recently elaborated in such concepts as eco......, Portugal and New Zealand have adopted the concept. Public sector interventions that aim to support cluster development in industries most often focus upon economic policy goals such as enhanced employment and improved productivity, but rarely emphasise broader societal policy goals relating to e...... to the automotive sector in Wales. Specifically, the paper evaluates the "Accelerates" programme initiated by the Welsh Development Agency and elaborates on how and to what extent the Accelerate programme supports the development of a sustainable automotive industry cluster. The Accelerate programme was set up...

  12. Particle formation in ambient MALDI plumes.

    Science.gov (United States)

    Musapelo, Thabiso; Murray, Kermit K

    2011-09-01

    The ablated particle count and size distribution of four solid matrix materials commonly used for matrix-assisted laser desorption ionization (MALDI) were measured with a scanning mobility particle sizer (SMPS) combined with a light scattering aerodynamic particle sizer (APS). The two particle sizing instruments allowed size measurements in the range from 10 nm to 20 μm. The four solid matrixes investigated were 2,5-dihydroxybenzoic acid (DHB), 4-nitroaniline (NA), α-cyano-4-hydroxycinnamic acid (CHCA), and sinapic acid (SA). A thin film of the matrix was deposited on a stainless steel target using the dried droplet method and was irradiated with a 337 nm nitrogen laser at atmospheric pressure. The target was rotated during the measurement. A large number of nanoparticles were produced, and average particle diameters ranged from 40 to 170 nm depending on the matrix and the laser fluence. These particles are attributed to agglomeration of smaller particles and clusters and/or hydrodynamic sputtering of melted matrix. A coarse particle component of the distribution was observed with diameters between 500 nm and 2 μm. The coarse particles were significantly lower in number but had a total mass that was comparable to that of the nanoparticles. The coarse particles are attributed to matrix melting and spallation. Two of the compounds, CHCA and SA, had a third particle size distribution component in the range of 10 to 30 nm, which is attributed to the direct ejection of clusters.

  13. Study of Plume Characteristics of a Stationary Plasma Thruster

    Institute of Scientific and Technical Information of China (English)

    QIAN Zhong; WANG Pingyang; DU Zhaohui; KANG Xiaolu

    2008-01-01

    Electron density and temperature of the plume are measured by a double Langmuir probe in an experimental chamber.A numerical model based on both particle-in-cell scheme and direct simulation Monte Carlo hybrid method is developed to simulate the flow field of plume.The equation for plasma potential is solved by alternative direction implicit technique. The simulation is verified by comparing the computational results with the measured data.The study indicates that the electron temperature of flow field is about 2 eV and the electron density is about 2.5 × 1016 ~ 5 × 1015 m-3 at the central line with a distance of 0.3 ~ 1.0 m downstream of the thruster exit.The model can well predict the flow field parameters of the steady plume.The efforts of this paper are referable for further investigation.

  14. An analytical and experimental investigation of resistojet plumes

    Science.gov (United States)

    Zana, Lynnette M.; Hoffman, David J.; Breyley, Loranell R.; Serafini, John S.

    1987-01-01

    As a part of the electrothermal propulsion plume research program at the NASA Lewis Research Center, efforts have been initiated to analytically and experimentally investigate the plumes of resistojet thrusters. The method of Simons for the prediction of rocket exhaust plumes is developed for the resistojet. Modifications are made to the source flow equations to account for the increased effects of the relatively large nozzle boundary layer. Additionally, preliminary mass flux measurements of a laboratory resistojet using CO2 propellant at 298 K have been obtained with a cryogenically cooled quartz crystal microbalance (QCM). There is qualitative agreement between analysis and experiment, at least in terms of the overall number density shape functions in the forward flux region.

  15. Analyzing rocket plume spectral data with neural networks

    Science.gov (United States)

    Whitaker, Kevin W.; Krishnakumar, K. S.; Benzing, Daniel A.

    1995-01-01

    The Optical Plume Anomaly Detection (OPAD) system is under development to provide early-warning failure detection in support of ground-level testing of the Space Shuttle Main Engine (SSME). Failure detection is to be achieved through the acquisition of spectrally resolved plume emissions and subsequent identification of abnormal levels indicative of engine corrosion or component failure. Two computer codes (one linear and the other non-linear) are used by the OPAD system to iteratively determine specific element concentrations in the SSME plume, given emission intensity and wavelength information. Since this analysis is extremely labor intensive, a study was initiated to develop neural networks that would model the 'inverse' of these computer codes. Optimally connected feed-forward networks with imperceptible prediction error have been developed for each element modeled by the linear code, SPECTRA4. Radial basis function networks were developed for the non-linear code, SPECTRA5, and predict combustion temperature in addition to element concentrations.

  16. Analyzing rocket plume spectral data with neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Whitaker, K.W.; Krishnakumar, K.S.; Benzing, D.A.

    1995-09-01

    The Optical Plume Anomaly Detection (OPAD) system is under development to provide early-warning failure detection in support of ground-level testing of the Space Shuttle Main Engine (SSME). Failure detection is to be achieved through the acquisition of spectrally resolved plume emissions and subsequent identification of abnormal levels indicative of engine corrosion or component failure. Two computer codes (one linear and the other non-linear) are used by the OPAD system to iteratively determine specific element concentrations in the SSME plume, given emission intensity and wavelength information. Since this analysis is extremely labor intensive, a study was initiated to develop neural networks that would model the `inverse` of these computer codes. Optimally connected feed-forward networks with imperceptible prediction error have been developed for each element modeled by the linear code, SPECTRA4. Radial basis function networks were developed for the non-linear code, SPECTRA5, and predict combustion temperature in addition to element concentrations.

  17. Turbulent Boyant Jets and Plumes in Flowing Ambient Environments

    DEFF Research Database (Denmark)

    Chen, Hai-Bo

    Turbulent buoyant jets and plumes in flowing ambient environments have been studied theoretically and experimentally. The mechanics of turbulent buoyant jets and plumes in flowing ambients have been discussed. Dimensional analysis was employed to investigate the mean behaviour of the turbulent...... and the stage of plume. The stability criteria for the upstream wedge created by the submerged turbulent buoyant jet were established by applying the Bernoulli equations for a two-dimensional problem and by considering the front velocity driven by the buoyancy force for a three-dimensional problem...... in a crossflowing environment, have been presented and successfully correlated using momentum and buoyancy fluxes and length scales. The analysis demonstrates that the experimental data on the jet trajectories and dilutions can be well correlated using the momentum or buoyancy fluxes and length scales, depending...

  18. Analyzing rocket plume spectral data with neural networks

    Science.gov (United States)

    Whitaker, Kevin W.; Krishnakumar, K. S.; Benzing, Daniel A.

    The Optical Plume Anomaly Detection (OPAD) system is under development to provide early-warning failure detection in support of ground-level testing of the Space Shuttle Main Engine (SSME). Failure detection is to be achieved through the acquisition of spectrally resolved plume emissions and subsequent identification of abnormal levels indicative of engine corrosion or component failure. Two computer codes (one linear and the other non-linear) are used by the OPAD system to iteratively determine specific element concentrations in the SSME plume, given emission intensity and wavelength information. Since this analysis is extremely labor intensive, a study was initiated to develop neural networks that would model the 'inverse' of these computer codes. Optimally connected feed-forward networks with imperceptible prediction error have been developed for each element modeled by the linear code, SPECTRA4. Radial basis function networks were developed for the non-linear code, SPECTRA5, and predict combustion temperature in addition to element concentrations.

  19. Electrical charging of ash in Icelandic volcanic plumes

    CERN Document Server

    Aplin, Karen L; Nicoll, Keri A

    2014-01-01

    The existence of volcanic lightning and alteration of the atmospheric potential gradient in the vicinity of near-vent volcanic plumes provides strong evidence for the charging of volcanic ash. More subtle electrical effects are also visible in balloon soundings of distal volcanic plumes. Near the vent, some proposed charging mechanisms are fractoemission, triboelectrification, and the so-called "dirty thunderstorm" mechanism, which is where ash and convective clouds interact electrically to enhance charging. Distant from the vent, a self-charging mechanism, probably triboelectrification, has been suggested to explain the sustained low levels of charge observed on a distal plume. Recent research by Houghton et al. (2013) linked the self-charging of volcanic ash to the properties of the particle size distribution, observing that a highly polydisperse ash distribution would charge more effectively than a monodisperse one. Natural radioactivity in some volcanic ash could also contribute to self-charging of volcan...

  20. SSME Condition Monitoring Using Neural Networks and Plume Spectral Signatures

    Science.gov (United States)

    Hopkins, Randall; Benzing, Daniel

    1996-01-01

    For a variety of reasons, condition monitoring of the Space Shuttle Main Engine (SSME) has become an important concern for both ground tests and in-flight operation. The complexities of the SSME suggest that active, real-time condition monitoring should be performed to avoid large-scale or catastrophic failure of the engine. In 1986, the SSME became the subject of a plume emission spectroscopy project at NASA's Marshall Space Flight Center (MSFC). Since then, plume emission spectroscopy has recorded many nominal tests and the qualitative spectral features of the SSME plume are now well established. Significant discoveries made with both wide-band and narrow-band plume emission spectroscopy systems led MSFC to develop the Optical Plume Anomaly Detection (OPAD) system. The OPAD system is designed to provide condition monitoring of the SSME during ground-level testing. The operational health of the engine is achieved through the acquisition of spectrally resolved plume emissions and the subsequent identification of abnormal emission levels in the plume indicative of engine erosion or component failure. Eventually, OPAD, or a derivative of the technology, could find its way on to an actual space vehicle and provide in-flight engine condition monitoring. This technology step, however, will require miniaturized hardware capable of processing plume spectral data in real-time. An objective of OPAD condition monitoring is to determine how much of an element is present in the SSME plume. The basic premise is that by knowing the element and its concentration, this could be related back to the health of components within the engine. For example, an abnormal amount of silver in the plume might signify increased wear or deterioration of a particular bearing in the engine. Once an anomaly is identified, the engine could be shut down before catastrophic failure occurs. Currently, element concentrations in the plume are determined iteratively with the help of a non-linear computer

  1. Cassini detection of Enceladus' cold water-group plume ionosphere

    Science.gov (United States)

    Tokar, R. L.; Johnson, R. E.; Thomsen, M. F.; Wilson, R. J.; Young, D. T.; Crary, F. J.; Coates, A. J.; Jones, G. H.; Paty, C. S.

    2009-07-01

    This study reports direct detection by the Cassini plasma spectrometer of freshly-produced water-group ions (O+, OH+, H2O+, H3O+) and heavier water dimer ions (HxO2)+ very close to Enceladus where the plasma begins to emerge from the plume. The data were obtained during two close (52 and 25 km) flybys of Enceladus in 2008 and are similar to ion data in cometary comas. The ions are observed in detectors looking in the Cassini ram direction exhibiting energies consistent with the Cassini speed, indicative of a nearly stagnant plasma flow in the plume. North of Enceladus the plasma slowing commences about 4 to 6 Enceladus radii away, while south of Enceladus signatures of the plasma interaction with the plume are detected 22 Enceladus radii away.

  2. Tidally induced lateral dispersion of the Storfjorden overflow plume

    Directory of Open Access Journals (Sweden)

    F. Wobus

    2013-10-01

    Full Text Available We investigate the flow of brine-enriched shelf water from Storfjorden (Svalbard into Fram Strait and onto the western Svalbard Shelf using a regional set-up of NEMO-SHELF, a 3-D numerical ocean circulation model. The model is set up with realistic bathymetry, atmospheric forcing, open boundary conditions and tides. The model has 3 km horizontal resolution and 50 vertical levels in the sh-coordinate system which is specially designed to resolve bottom boundary layer processes. In a series of modelling experiments we focus on the influence of tides on the propagation of the dense water plume by comparing results from tidal and non-tidal model runs. Comparisons of non-tidal to tidal simulations reveal a hotspot of tidally induced horizontal diffusion leading to the lateral dispersion of the plume at the southernmost headland of Spitsbergen which is in close proximity to the plume path. As a result the lighter fractions in the diluted upper layer of the plume are drawn into the shallow coastal current that carries Storfjorden water onto the western Svalbard Shelf, while the dense bottom layer continues to sink down the slope. This bifurcation of the plume into a diluted shelf branch and a dense downslope branch is enhanced by tidally induced shear dispersion at the headland. Tidal effects at the headland are shown to cause a net reduction in the downslope flux of Storfjorden water into the deep Fram Strait. This finding contrasts previous results from observations of a dense plume on a different shelf without abrupt topography.

  3. Satellite detection of wastewater diversion plumes in Southern California

    Science.gov (United States)

    Gierach, Michelle M.; Holt, Benjamin; Trinh, Rebecca; Jack Pan, B.; Rains, Christine

    2017-02-01

    Multi-sensor satellite observations proved useful in detecting surfacing wastewater plumes during the 2006 Hyperion Treatment Plant (HTP) and 2012 Orange County Sanitation District (OCSD) wastewater diversion events in Southern California. Satellite sensors were capable of detecting biophysical signatures associated with the wastewater, compared to ambient ocean waters, enabling monitoring of environmental impacts over a greater spatial extent than in situ sampling alone. Thermal satellite sensors measured decreased sea surface temperatures (SSTs) associated with the surfacing plumes. Ocean color satellite sensors did not measure a distinguishable biological response in terms of chlorophyll-a (chl-a) concentrations during the short lived, three-day long, 2006 HTP diversion. A period of decreased chl-a concentration was observed during the three-week long 2012 OCSD diversion, likely in association with enhanced chlorination of the discharged wastewater that suppressed the phytoplankton response and/or significant uptake by heterotrophic bacteria. Synthetic aperture radar (SAR) satellite data were able to identify and track the 2006 HTP wastewater plume through changes in surface roughness related to the oily components of the treated surfacing wastewater. Overall, it was found that chl-a and SST values must have differences of at least 1 mg m-3 and 0.5 °C, respectively, in comparison with adjacent waters for wastewater plumes and their biophysical impact to be detectable from satellite. For a wastewater plume to be identifiable in SAR imagery, wind speeds must range between ∼3 and 8 m s-1. The findings of this study illustrate the benefit of utilizing multiple satellite sensors to monitor the rapidly changing environmental response to surfacing wastewater plumes, and can help inform future wastewater diversions in coastal areas.

  4. IASI measurements of reactive trace species in biomass burning plumes

    Directory of Open Access Journals (Sweden)

    P.-F. Coheur

    2009-08-01

    Full Text Available This work presents observations of a series of short-lived species in biomass burning plumes from the Infrared Atmospheric Sounding Interferometer (IASI, launched onboard the MetOp-A platform in October 2006. The strong fires that have occurred in the Mediterranean Basin – and particularly Greece – in August 2007, and those in Southern Siberia and Eastern Mongolia in the early spring of 2008 are selected to support the analyses. We show that the IASI infrared spectra in these fire plumes contain distinctive signatures of ammonia (NH3, ethene (C2H4, methanol (CH3OH and formic acid (HCOOH in the atmospheric window between 800 and 1200 cm−1, with some noticeable differences between the plumes. Peroxyacetyl nitrate (CH3COOONO2, abbreviated as PAN was also observed with good confidence in some plumes and a tentative assignment of a broadband absorption spectral feature to acetic acid (CH3COOH is made. For several of these species these are the first reported measurements made from space in nadir geometry. The IASI measurements are analyzed for plume height and concentration distributions of NH3, C2H4 and CH3OH. The Greek fires are studied in greater detail for the days associated with the largest emissions. In addition to providing information on the spatial extent of the plume, the IASI retrievals allow an estimate of the total mass emissions for NH3, C2H4 and CH3OH. Enhancement ratios are calculated for the latter relative to carbon monoxide (CO, giving insight in the chemical processes occurring during the transport, the first day after the emission.

  5. Aerosol nucleation in coal-fired power-plant plumes

    Science.gov (United States)

    Stevens, Robin; Lonsdale, Chantelle; Brock, Charles; Makar, Paul; Knipping, Eladio; Reed, Molly; Crawford, James; Holloway, John; Ryerson, Tim; Huey, L. Greg; Nowak, John; Pierce, Jeffrey

    2013-05-01

    New-particle nucleation within coal-fired power-plant plumes can have large effects on particle number concentrations, particularly near source regions, with implications for human health and climate. In order to resolve the formation and growth of particles in these plumes, we have integrated TwO-Moment Aerosol Sectional (TOMAS) microphysics in the System for Atmospheric Modelling (SAM), a large-eddy simulation/cloud-resolving model (LES/CRM). We have evaluated this model against aircraft observations for three case studies, and the model reproduces well the major features of each case. Using this model, we have shown that meteorology and background aerosol concentrations can have strong effects on new-particle formation and growth in coal-fired power-plant plumes, even if emissions are held constant. We subsequently used the model to evaluate the effects of SO2 and NOx pollution controls on newparticle formation in coal-fired power-plant plumes. We found that strong reductions in NOx emissions without concurrent reductions in SO2 emissions may increase new-particle formation, due to increases in OH formation within the plume. We predicted the change in new-particle formation due to changes in emissions between 1997 and 2010 for 330 coal-fired power plants in the US, and we found a median decrease of 19% in new-particle formation. However, the magnitude and sign of the aerosol changes depend greatly on the relative reductions in NOx and SO2 emissions in each plant. More extensive plume measurements for a range of emissions of SO2 and NOx and in varying background aerosol conditions are needed, however, to better quantify these effects.

  6. Cluster forcing

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    The cluster theory attributed to Michael Porter has significantly influenced industrial policies in countries across Europe and North America since the beginning of the 1990s. Institutions such as the EU, OECD and the World Bank and governments in countries such as the UK, France, The Netherlands...

  7. Exposure estimates using urban plume dispersion and traffic microsimulation models

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.J.; Mueller, C.; Bush, B.; Stretz, P.

    1997-12-01

    The goal of this research effort was to demonstrate a capability for analyzing emergency response issues resulting from accidental or mediated airborne toxic releases in an urban setting. In the first year of the program, the authors linked a system of fluid dynamics, plume dispersion, and vehicle transportation models developed at Los Alamos National Laboratory to study the dispersion of a plume in an urban setting and the resulting exposures to vehicle traffic. This research is part of a larger laboratory-directed research and development project for studying the relationships between urban infrastructure elements and natural systems.

  8. Odor identity influences tracking of temporally patterned plumes in Drosophila

    Directory of Open Access Journals (Sweden)

    Frye Mark A

    2011-06-01

    Full Text Available Abstract Background Turbulent fluid landscapes impose temporal patterning upon chemical signals, and the dynamical neuronal responses to patterned input vary across the olfactory receptor repertoire in flies, moths, and locusts. Sensory transformations exhibit low pass filtering that ultimately results in perceptual fusion of temporally transient sensory signals. For example, humans perceive a sufficiently fast flickering light as continuous, but the frequency threshold at which this fusion occurs varies with wavelength. Although the summed frequency sensitivity of the fly antenna has been examined to a considerable extent, it is unknown how intermittent odor signals are integrated to influence plume tracking behavior independent of wind cues, and whether temporal fusion for behavioral tracking might vary according to the odor encountered. Results Here we have adopted a virtual reality flight simulator to study the dynamics of plume tracking under different experimental conditions. Flies tethered in a magnetic field actively track continuous (non-intermittent plumes of vinegar, banana, or ethyl butyrate with equal precision. However, pulsing these plumes at varying frequency reveals that the threshold rate, above which flies track the plume as if it were continuous, is unique for each odorant tested. Thus, the capability of a fly to navigate an intermittent plume depends on the particular odorant being tracked during flight. Finally, we measured antennal field potential responses to an intermittent plume, found that receptor dynamics track the temporal pattern of the odor stimulus and therefore do not limit the observed behavioral temporal fusion limits. Conclusions This study explores the flies' ability to track odor plumes that are temporally intermittent. We were surprised to find that the perceptual critical fusion limit, determined behaviorally, is strongly dependent on odor identity. Antennal field potential recordings indicate that

  9. Plume Mitigation: Soil Erosion and Lunar Prospecting Sensor Project

    Science.gov (United States)

    Metzger, Philip T.

    2014-01-01

    Demonstrate feasibility of the simplest, lowest-mass method of measuring density of a cloud of lunar soil ejected by rocket exhaust, using new math techniques with a small baseline laser/camera system. Focus is on exploring the erosion process that occurs when the exhaust plume of a lunar rocket impacts the regolith. Also, predicting the behavior of the lunar soil that would be blasted from a lunar landing/launch site shall assist in better design and protection of any future lunar settlement from scouring of structures and equipment. NASA is gathering experimental data to improve soil erosion models and understand how lunar particles enter the plume flow.

  10. Anatomy of mantle plumes: hot heads and cold stems

    Science.gov (United States)

    Davaille, A. B.; Kumagai, I.; Vatteville, J.; Touitou, F.; Brandeis, G.

    2012-12-01

    Recent petrological studies show evidences for secular cooling in mantle plumes: the source temperature of oceanic plateaus could be 100°C hotter than the source temperature of volcanic island chains (Herzberg and Gazel, Nature, 2009). In terms of mantle plumes, it would mean that the temperature of the plume head is hotter than that of the plume stem. This is at odd with a model where a plume head would entrain so much ambient mantle on its journey towards the Earth's surface that it would end up being considerably colder than its narrow stem. So we revisited the problem using laboratory experiments and new visualization techniques to measure in situ simultaneously the temperature, velocity and composition fields. At time t=0, a hot instability is created by heating a patch of a given radius at constant power or constant temperature. The fluids are mixtures of sugar syrups , with a strongly temperature-dependent viscosity, and salt. Rayleigh numbers were varied from 104 to 108, viscosity ratios between 1.8 and 4000, and buoyancy ratios between 0 and 2. After a stage where heat transport is by conduction only, the hot fluid gathers in a sphere and begins to rise, followed by a stem anchored on the hot patch. In all cases, temperatures in the head start with higher values than in the subsequent stem. This is also the case for the thermal instabilities rising from a infinite plate heated uniformly. However, the head also cools faster than the stem as they rise, so that they will eventually have the same temperature if the mantle is deep enough. Moreover, all the material sampled by partial melting in the plume head or stem would be coming from the heated area around the deep source, and very little entrainment from the ambient mantle is predicted. The difference in temperature between head and stem strongly depends on the mantle depth, the viscosity ratio and the buoyancy ratio. Our scaling laws predict that Earth's mantle plumes can indeed have hot heads and colder

  11. Redox zones of a landfill leachate pollution plume (Vejen, Denmark)

    DEFF Research Database (Denmark)

    Lyngkilde, John; Christensen, Thomas Højlund

    1992-01-01

    Downgradient from an old municipal landfill allowing leachate, rich in dissolved organic carbon, to enter a shallow sandy aerobic aquifer, a sequence of redoxe zones is identified from groundwater chemical analysis. Below the landfill, methanogenic conditions prevail, followed by sulfidogenic......, ferrogenic, nitrate-reducing and aerobic environments overa distance of 370 m. This redox zone sequence is consistent with thermodynamical principles and is closely matched by the leachate plume determined by the chloride plume distribution. The redox zone sequence is believed to be key in controlling...

  12. Mixing between a stratospheric intrusion and a biomass burning plume

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2007-08-01

    Full Text Available Ozone, carbon monoxide, aerosol extinction coefficient, acetonitrile, nitric acid and relative humidity measured from the NOAA P3 aircraft during the TexAQS/GoMACCS 2006 experiment, indicate mixing between a biomass burning plume and a stratospheric intrusion in the free troposphere above eastern Texas. Lagrangian-based transport analysis and satellite imagery are used to investigate the transport mechanisms that bring together the tropopause fold and the biomass burning plume originating in southern California, which may affect the chemical budget of tropospheric trace gases.

  13. Mixing between a stratospheric intrusion and a biomass burning plume

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2007-06-01

    Full Text Available Ozone, carbon monoxide, aerosol extinction coefficient, acetonitrile, nitric acid and relative humidity measured from the NOAA P3 aircraft during the TexAQS/GoMACCS 2006 experiment, indicate mixing between a biomass burning plume and a stratospheric intrusion in the free troposphere above eastern Texas. Lagrangian-based transport analysis and satellite imagery are used to investigate the transport mechanisms that bring together the tropopause fold and the biomass burning plume originating in southern California, which may affect the chemical budget of tropospheric trace gases.

  14. Polar plumes dynamics observed during total solar eclipses

    Science.gov (United States)

    Barczynski, K.; Bělík, M.; Marková, E.

    2010-12-01

    Following the successful observation of significant activity in the polar plume during the total solar eclipse in 2006, the analysis of the Sun's polar regions was also carried out in the images obtained in multi-station observations of the eclipse of 2008. In this work polar plumes showing similar although much less significant manifestation of the dynamics have been identified. The dynamics evolution rates have been obtained from comparing the pictures taken at different times. The results are compared with the corresponding phenomena observed in X-rays from the HINODE satellite.

  15. Assessment of analytical techniques for predicting solid propellant exhaust plumes

    Science.gov (United States)

    Tevepaugh, J. A.; Smith, S. D.; Penny, M. M.

    1977-01-01

    The calculation of solid propellant exhaust plume flow fields is addressed. Two major areas covered are: (1) the applicability of empirical data currently available to define particle drag coefficients, heat transfer coefficients, mean particle size and particle size distributions, and (2) thermochemical modeling of the gaseous phase of the flow field. Comparisons of experimentally measured and analytically predicted data are made. The experimental data were obtained for subscale solid propellant motors with aluminum loadings of 2, 10 and 15%. Analytical predictions were made using a fully coupled two-phase numerical solution. Data comparisons will be presented for radial distributions at plume axial stations of 5, 12, 16 and 20 diameters.

  16. Electron loss rates from the outer radiation belt caused by the filling of the outer plasmasphere: the calm before the storm

    Energy Technology Data Exchange (ETDEWEB)

    Borovsky, Joseph E [Los Alamos National Laboratory; Denton, Michael H [LANCASTER UNIV

    2009-01-01

    Measurements from 7 spacecraft in geosynchronous orbit are analyzed to determine the decay rate of the number density of the outer electron radiation belt prior to the onset of high-speed-stream-driven geomagnetic storms. Superposed-data analysis is used wan(?) a collection of 124 storms. When there is a calm before the storm, the electron number density decays exponentially before the storm with a 3.4-day e-folding time: beginning about 4 days before storm onset, the density decreases from {approx}4x10{sup -4} cm{sup -3} to {approx}1X 10{sup -4} cm{sup -3}. When there is not a calm before the storm, the number-density decay is very smalL The decay in the number density of radiation-belt electrons is believed to be caused by pitch-angle scattering of electrons into the atmospheric loss cone as the outer plasmasphere fills during the calms. While the radiation-belt electron density decreases, the temperature of the electron radiation belt holds approximately constant, indicating that the electron precipitation occurs equally at all energies. Along with the number density decay, the pressure of the outer electron radiation belt decays and the specific entropy increases. From the measured decay rates, the electron flux to the atmosphere is calculated and that flux is 3 orders of magnitude less than thermal fluxes in the magnetosphere, indicating that the radiation-belt pitch-angle scattering is 3 orders weaker than strong diffusion. Energy fluxes into the atmosphere are calculated and found to be insufficient to produce visible airglow.

  17. STUDIES OF TWO-PHASE PLUMES IN STRATIFIED ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Scott A. Socolofsky; Brian C. Crounse; E. Eric Adams

    1998-11-18

    Two-phase plumes play an important role in the more practical scenarios for ocean sequestration of CO{sub 2}--i.e. dispersing CO{sub 2} as a buoyant liquid from either a bottom-mounted or ship-towed pipeline. Despite much research on related applications, such as for reservoir destratification using bubble plumes, our understanding of these flows is incomplete, especially concerning the phenomenon of plume peeling in a stratified ambient. To address this deficiency, we have built a laboratory facility in which we can make fundamental measurements of plume behavior. Although we are using air, oil and sediments as our sources of buoyancy (rather than CO{sub 2}), by using models, our results can be directly applied to field scale CO{sub 2} releases to help us design better CO{sub 2} injection systems, as well as plan and interpret the results of our up-coming international field experiment. The experimental facility designed to study two-phase plume behavior similar to that of an ocean CO{sub 2} release includes the following components: 1.22 x 1.22 x 2.44 m tall glass walled tank; Tanks and piping for the two-tank stratification method for producing step- and linearly-stratified ambient conditions; Density profiling system using a conductivity and temperature probe mounted to an automated depth profiler; Lighting systems, including a virtual point source light for shadowgraphs and a 6 W argon-ion laser for laser induced fluorescence (LIF) imaging; Imaging system, including a digital, progressive scanning CCD camera, computerized framegrabber, and image acquisition and analysis software; Buoyancy source diffusers having four different air diffusers, two oil diffusers, and a planned sediment diffuser; Dye injection method using a Mariotte bottle and a collar diffuser; and Systems integration software using the Labview graphical programming language and Windows NT. In comparison with previously reported experiments, this system allows us to extend the parameter range of

  18. 77 FR 4614 - Culturally Significant Objects Imported for Exhibition Determinations: “Children of the Plumed...

    Science.gov (United States)

    2012-01-30

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Culturally Significant Objects Imported for Exhibition Determinations: ``Children of the Plumed Serpent: The... exhibition ``Children of the Plumed Serpent: The Legacy of Quetzalcoatl in Ancient Mexico,'' imported...

  19. Sediment plume response to surface melting and supraglacial lake drainages on the Greenland ice sheet

    DEFF Research Database (Denmark)

    Chu, Vena W.; Smith, Laurence C; Rennermalm, Asa K.

    2009-01-01

    of a downstream sediment plume in Kangerlussuaq Fjord by comparing: (1) plume area and suspended sediment concentration from Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and field data; (2) ice-sheet melt extent from Special Sensor Microwave/Imager (SSM/I) passive microwave data; and (3......) supraglacial lake drainage events from MODIS. Results confirm that the origin of the sediment plume is meltwater release from the ice sheet. Interannual variations in plume area reflect interannual variations in surface melting. Plumes appear almost immediately with seasonal surface-melt onset, provided...... the estuary is free of landfast sea ice. A seasonal hysteresis between melt extent and plume area suggests late-season exhaustion in sediment supply. Analysis of plume sensitivity to supraglacial events is less conclusive, with 69% of melt pulses and 38% of lake drainage events triggering an increase in plume...

  20. The impact of glacier geometry on meltwater plume structure and submarine melt in Greenland fjords

    NARCIS (Netherlands)

    Carroll, D.; Sutherland, D. A.; Hudson, B.; Moon, T.; Catania, G. A.; Shroyer, E. L.; Nash, J. D.; Bartholomaus, T. C.; Felikson, D.; Stearns, L. A.; Noël, B. P Y|info:eu-repo/dai/nl/370612345; van den Broeke, M. R.|info:eu-repo/dai/nl/073765643

    2016-01-01

    Meltwater from the Greenland Ice Sheet often drains subglacially into fjords, driving upwelling plumes at glacier termini. Ocean models and observations of submarine termini suggest that plumes enhance melt and undercutting, leading to calving and potential glacier destabilization. Here we

  1. Quotients of cluster categories

    OpenAIRE

    Jorgensen, Peter

    2007-01-01

    Higher cluster categories were recently introduced as a generalization of cluster categories. This paper shows that in Dynkin types A and D, half of all higher cluster categories are actually just quotients of cluster categories. The other half can be obtained as quotients of 2-cluster categories, the "lowest" type of higher cluster categories. Hence, in Dynkin types A and D, all higher cluster phenomena are implicit in cluster categories and 2-cluster categories. In contrast, the same is not...

  2. The He isotope composition of the earliest picrites erupted by the Ethiopia plume, implications for mantle plume source

    Science.gov (United States)

    Stuart, Finlay; Rogers, Nick; Davies, Marc

    2016-04-01

    The earliest basalts erupted by mantle plumes are Mg-rich, and typically derived from mantle with higher potential temperature than those derived from the convecting upper mantle at mid-ocean ridges and ocean islands. The chemistry and isotopic composition of picrites from CFB provide constraints on the composition of deep Earth and thus the origin and differentiation history. We report new He-Sr-Nd-Pb isotopic composition of the picrites from the Ethiopian flood basalt province from the Dilb (Chinese Road) section. They are characterized by high Fe and Ti contents for MgO = 10-22 wt. % implying that the parent magma was derived from a high temperature low melt fraction, most probably from the Afar plume head. The picrite 3He/4He does not exceed 21 Ra, and there is a negative correlation with MgO, the highest 3He/4He corresponding to MgO = 15.4 wt. %. Age-corrected 87Sr/86Sr (0.70392-0.70408) and 143Nd/144Nd (0.512912-0.512987) display little variation and are distinct from MORB and OIB. Age-corrected Pb isotopes display a significant range (e.g. 206Pb/204Pb = 18.70-19.04) and plot above the NHRL. These values contrast with estimates of the modern Afar mantle plume which has lower 3He/4He and Sr, Nd and Pb isotope ratios that are more comparable with typical OIB. These results imply either interaction between melts derived from the Afar mantle plume and a lithospheric component, or that the original Afar mantle plume had a rather unique radiogenic isotope composition. Regardless of the details of the origins of this unusual signal, our observations place a minimum 3He/4He value of 21 Ra for the Afar mantle plume, significantly greater than the present day value of 16 Ra, implying a significant reduction over 30 Myr. In addition the Afar source was less degassed than convecting mantle but more degassed than mantle sampled by the proto-Iceland plume (3He/4He ~50 Ra). This suggests that the largest mantle plumes are not sourced in a single deep mantle domain with a

  3. Survey of ELF-VLF plasma waves in outer radiation belt observed by Cluster STAFF-SA experiment

    Directory of Open Access Journals (Sweden)

    D. Pokhotelov

    2008-10-01

    Full Text Available Various types of plasma waves have profound effects on acceleration and scattering of radiation belt particles. For the purposes of radiation belt modeling it is necessary to know statistical distributions of plasma wave parameters. This paper analyzes four years of plasma wave observations in the Earth's outer radiation belt obtained by the STAFF-SA experiment on board Cluster spacecraft. Statistical distributions of spectral density of different plasma waves observed in ELF-VLF range (chorus, plasmaspheric hiss, magnetosonic waves are presented as a function of magnetospheric coordinates and geomagnetic activity indices. Comparison with other spacecraft studies supports some earlier conclusions about the distribution of chorus and hiss waves and helps to remove the long-term controversy regarding the distribution of equatorial magnetosonic waves. This study represents a step towards the development of multi-spacecraft database of plasma wave activity in radiation belts.

  4. Regional Innovation Clusters

    Data.gov (United States)

    Small Business Administration — The Regional Innovation Clusters serve a diverse group of sectors and geographies. Three of the initial pilot clusters, termed Advanced Defense Technology clusters,...

  5. Experimental Investigation of Two Interacting Thruster-Plumes Downstream of the Nozzles

    OpenAIRE

    Holz, André; Dettleff, Georg; Hannemann, Klaus; Ziegenhagen, Stefan

    2012-01-01

    The plume-plume interaction of two small cold gas thrusters is investigated under high vacuum conditions in the DLR high vacuum plume test facility STG-CT. In this paper we concentrate on the interaction downstream of the nozzles. After introducing the experimental equipment, characteristics of shock interaction are presented. Furthermore the appropriateness of the Penetration Knudsen Number for predicting the type of interaction also for thruster plumes is investigated.

  6. Estimation of Volcanic Ash Plume Top Height using AATSR

    Science.gov (United States)

    Virtanen, Timo; Kolmonen, Pekka; Sogacheva, Larisa; Sundström, Anu-Maija; Rodriguez, Edith; de Leeuw, Gerrit

    2015-04-01

    The AATSR Correlation Method (ACM) height estimation algorithm is presented. The algorithm uses Advanced Along Track Scanning Radiometer (AATSR) satellite data to detect volcanic ash plumes and to estimate the plume top height. The height estimate is based on the stereo-viewing capability of the AATSR instrument, which allows to determine the parallax between the satellite's 55° forward and nadir views, and thus the corresponding height. Besides the stereo view, AATSR provides another advantage compared to other satellite based instruments. With AATSR it is possible to detect ash plumes using brightness temperature difference between thermal infrared (TIR) channels centered at 11 and 12 µm. The automatic ash detection makes the algorithm efficient in processing large quantities of data: the height estimate is calculated only for the ash-flagged pixels. In addition, it is possible to study the effect of using different wavelengths in the height estimate, ranging from visible (555 nm) to thermal infrared (12 µm). The ACM algorithm can be applied to the Sea and Land Surface Temperature Radiometer (SLSTR), scheduled for launch at the end of 2015. Accurate information on the volcanic ash position is important for air traffic safety. The ACM algorithm can provide valuable data of both horizontal and vertical ash dispersion. These data may be useful for comparisons with existing volcanic ash dispersion models and retrieval methods. We present ACM plume top height estimate results for the Eyjafjallajökull eruption, and comparisons against available ground based and satellite observations.

  7. Experiments on metal-silicate plumes and core formation.

    Science.gov (United States)

    Olson, Peter; Weeraratne, Dayanthie

    2008-11-28

    Short-lived isotope systematics, mantle siderophile abundances and the power requirements of the geodynamo favour an early and high-temperature core-formation process, in which metals concentrate and partially equilibrate with silicates in a deep magma ocean before descending to the core. We report results of laboratory experiments on liquid metal dynamics in a two-layer stratified viscous fluid, using sucrose solutions to represent the magma ocean and the crystalline, more primitive mantle and liquid gallium to represent the core-forming metals. Single gallium drop experiments and experiments on Rayleigh-Taylor instabilities with gallium layers and gallium mixtures produce metal diapirs that entrain the less viscous upper layer fluid and produce trailing plume conduits in the high-viscosity lower layer. Calculations indicate that viscous dissipation in metal-silicate plumes in the early Earth would result in a large initial core superheat. Our experiments suggest that metal-silicate mantle plumes facilitate high-pressure metal-silicate interaction and may later evolve into buoyant thermal plumes, connecting core formation to ancient hotspot activity on the Earth and possibly on other terrestrial planets.

  8. Acute Exposure Guideline Levels (AEGLs) for Time Varying Toxic Plumes

    Science.gov (United States)

    2014-09-12

    1.0 ! The plume densities are not scaled ... Agent = ’NH3’ Agent = ’ PLm ’ ! Any power from 0.0 to 9.0 Agent = ’CL2...Agent will be PLm Call POWER_LAW_AEGL ( power, Arho_PLC, Atime ) Call AGENT_SETUP ( Agent, Arho_PLC, taumin, taumax

  9. Analysis of Volcanic Plume Detection on Mount Etna through GPS

    Science.gov (United States)

    Cannavo, F.; Aranzulla, M.; Scollo, S.; Puglisi, G.; Imme', G.

    2013-12-01

    Volcanic ash produced during explosive eruptions causes disruptions to aviation operations and to population living around active volcanoes. In order to reduce their impact, the detection of volcanic plume is a necessary step and this is usually carried out using different platforms such as satellites, radars and lidars. Recently, the capability of GPS to retrieve volcanic plumes has been also investigated and some tests applied to explosive activity of Etna have demonstrated that also the GPS may give useful information. In this work, we use the permanent and continuous GPS network of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo (Italy) that consists of 35 stations located all around volcano flanks. Data are processed by the GAMIT package developed by Massachusetts Institute of Technology. Here we investigate the possibility to detect the volcanic plume through the GPS signal features and to estimate its spatial distribution by means of a tomographic inversion algorithm. The method is tested on volcanic plumes produced during the lava fountain of 4-5 September 2007, already used to confirm if weak explosive activity may or may not affect the GPS signals. Others tests were finally applied to some lava fountains produced during the recent Etna explosive activity between 2011 and 2013.

  10. Hydrothermal plumes over the Carlsberg Ridge, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ray, D.; KameshRaju, K.A.; Baker, E.T.; Rao, A.S.; Mudholkar, A.V.; Lupton, J.E.; SuryaPrakash, L.; Gawas, R.B.; VijayaKumar, T.

    robust light-scattering and ORP anomalies at multiple depths, implying multiple sources. ORP anomalies are very short-lived, so the strong signals at both sites suggest that fluid sources lie within a few kilometers or less from the plume sampling...

  11. Atmospheric ventilation corridors and coefficients for pollution plume ...

    African Journals Online (AJOL)

    Tuoyo Aghomotsegin

    for gaseous pollution plume released from an isolated industrial facility into the ambient air of the host ...... ventilation coefficient and its impact on urban air pollution. J. Cent. ... an iron and steel smelting plant located along a busy high way in.

  12. Laser ablation plume expansion into an ambient gas

    DEFF Research Database (Denmark)

    Amoruso, S.; Schou, Jørgen; Lunney, J.G.

    2009-01-01

    The use of an ambient gas is a well-established method employed in pulsed laser deposition (PLD) with nanosecond pulses and has been extensively studied in this context. Most of the existing treatments of the plume expansion are tackled by using complex numerical modeling involving specific target...

  13. The Growth and Decay of Equatorial Backscatter Plumes.

    Science.gov (United States)

    1980-02-01

    spatially connected to bottomside backscatter, a feature noted in Jica - marca radar observations that led Woodman and La Hoz (1976) to speculate that...described in Section Ill-B, this pattern of plume growth resembles the "C-shaped" and "fishtail" patterns found in Jica - marca radar RTI displays of 50-MHz

  14. Limited latitudinal mantle plume motion for the Louisville hotspot

    Science.gov (United States)

    Koppers, Anthony A. P.; Yamazaki, Toshitsugu; Geldmacher, Jörg; Gee, Jeffrey S.; Pressling, Nicola; Koppers, Anthony A. P.; Yamazaki, Toshitsugu; Geldmacher, Jörg; Gee, Jeffrey S.; Pressling, Nicola; Hoshi, Hiroyuki; Anderson, L.; Beier, C.; Buchs, D. M.; Chen, L.-H.; Cohen, B. E.; Deschamps, F.; Dorais, M. J.; Ebuna, D.; Ehmann, S.; Fitton, J. G.; Fulton, P. M.; Ganbat, E.; Hamelin, C.; Hanyu, T.; Kalnins, L.; Kell, J.; Machida, S.; Mahoney, J. J.; Moriya, K.; Nichols, A. R. L.; Rausch, S.; Sano, S.-I.; Sylvan, J. B.; Williams, R.

    2012-12-01

    Hotspots that form above upwelling plumes of hot material from the deep mantle typically leave narrow trails of volcanic seamounts as a tectonic plate moves over their location. These seamount trails are excellent recorders of Earth's deep processes and allow us to untangle ancient mantle plume motions. During ascent it is likely that mantle plumes are pushed away from their vertical upwelling trajectories by mantle convection forces. It has been proposed that a large-scale lateral displacement, termed the mantle wind, existed in the Pacific between about 80 and 50 million years ago, and shifted the Hawaiian mantle plume southwards by about 15° of latitude. Here we use 40Ar/39Ar age dating and palaeomagnetic inclination data from four seamounts associated with the Louisville hotspot in the South Pacific Ocean to show that this hotspot has been relatively stable in terms of its location. Specifically, the Louisville hotspot--the southern hemisphere counterpart of Hawai'i--has remained within 3-5° of its present-day latitude of about 51°S between 70 and 50 million years ago. Although we cannot exclude a more significant southward motion before that time, we suggest that the Louisville and Hawaiian hotspots are moving independently, and not as part of a large-scale mantle wind in the Pacific.

  15. Vapor plumes: A neglected aspect of impact cratering

    Science.gov (United States)

    Melosh, H. J.

    1991-06-01

    When a meteorite or comet strikes the surface of the planet or satellite at typical interplanetary velocities of 10-40 km/sec, the projectile and a quantity of the target body vaporize and expand out of the growing crater at high speed. The crater continues to grow after the vapor plume has formed and the series of ejecta deposits is laid down ballistically while the crater collapses into its final morphology. Although the vapor plume leaves little evidence of its existence in the crater structure of surface deposits, it may play a major role in a number of impact-related processes. The vapor plume expanding away from the site of an impact carries 25-50 percent of the total impact energy. Although the plume's total mass is only a few times the mass of the projectile, its high specific energy content means that it is the fastest and most highly shocked material in the cratering event. The mean velocity of expansion can easily exceed the escape velocity of the target plane, so that the net effect of a sufficiently high-speed impact is to erode material from the planet.

  16. Electrical conductivity of the dusty plasma in the Enceladus plume

    Science.gov (United States)

    Yaroshenko, V. V.; Lühr, H.

    2016-11-01

    The plasma conductivity is an important issue for understanding the magnetic field structure registered by Cassini in the Enceladus proximity. We have revise the conductivity mechanism to incorporate the plume nanograins as a new plasma species and take into account the relevant collisional processes including those accounting for the momentum exchange between the charged dust and co-rotating ions. It is concluded that in the Enceladus plume the dust dynamics affects the Pedersen and Hall conductivity more efficiently than the electron depletion associated with the presence of the negatively charged dust as has been suggested by Simon et al. (Simon, S., Saur, J., Kriegel, H., Neubauer, F. M., Motschmann, U., and Dougherty, U. [2011] J. Geophys. Res., 116, A04221, doi:10.1029/2010JA016338). The electron depletion remains a decisive factor for only the parallel conductivity. In the parameter regime relevant for the Enceladus plume, one finds increase of the Pedersen and decrease of the parallel components, whereas for the Hall conductivity the charged dust changes both - its value and the sign. The associated reversed Hall effect depends significantly upon the local dust-to-plasma density ratio. An onset of the reversed Hall effect appears to be restricted to outer parts of the Enceladus plume. The results obtained can significantly modify Enceladus' Alfvén wing structure and thus be useful for interpretations of the magnetic field perturbations registered by the Cassini Magnetometer during the close Enceladus flybys.

  17. Ion Engine Plume Interaction Calculations for Prototypical Prometheus 1

    Science.gov (United States)

    Mandell, Myron J.; Kuharski, Robert A.; Gardner, Barbara M.; Katz, Ira; Randolph, Tom; Dougherty, Ryan; Ferguson, Dale C.

    2005-01-01

    Prometheus 1 is a conceptual mission to demonstrate the use of atomic energy for distant space missions. The hypothetical spacecraft design considered in this paper calls for multiple ion thrusters, each with considerably higher beam energy and beam current than have previously flown in space. The engineering challenges posed by such powerful thrusters relate not only to the thrusters themselves, but also to designing the spacecraft to avoid potentially deleterious effects of the thruster plumes. Accommodation of these thrusters requires good prediction of the highest angle portions of the main beam, as well as knowledge of clastically scattered and charge exchange ions, predictions for grid erosion and contamination of surfaces by eroded grid material, and effects of the plasma plume on radio transmissions. Nonlinear interactions of multiple thrusters are also of concern. In this paper we describe two- and three-dimensional calculations for plume structure and effects of conceptual Prometheus 1 ion engines. Many of the techniques used have been validated by application to ground test data for the NSTAR and NEXT ion engines. Predictions for plume structure and possible sputtering and contamination effects will be presented.

  18. Rejuvenation of the lithosphere by the Hawaiian plume.

    Science.gov (United States)

    Li, Xueqing; Kind, Rainer; Yuan, Xiaohui; Wölbern, Ingo; Hanka, Winfried

    2004-02-26

    The volcanism responsible for creating the chain of the Hawaiian islands and seamounts is believed to mark the passage of the oceanic lithosphere over a mantle plume. In this picture hot material rises from great depth within a fixed narrow conduit to the surface, penetrating the moving lithosphere. Although a number of models describe possible plume-lithosphere interactions, seismic imaging techniques have not had sufficient resolution to distinguish between them. Here we apply the S-wave 'receiver function' technique to data of three permanent seismic broadband stations on the Hawaiian islands, to map the thickness of the underlying lithosphere. We find that under Big Island the lithosphere is 100-110 km thick, as expected for an oceanic plate 90-100 million years old that is not modified by a plume. But the lithosphere thins gradually along the island chain to about 50-60 km below Kauai. The width of the thinning is about 300 km. In this zone, well within the larger-scale topographic swell, we infer that the rejuvenation model (where the plume thins the lithosphere) is operative; however, the larger-scale topographic swell is probably supported dynamically.

  19. Merits of a Scenario Approach in Dredge Plume Modelling

    DEFF Research Database (Denmark)

    Pedersen, Claus; Chu, Amy Ling Chu; Hjelmager Jensen, Jacob

    2011-01-01

    Dredge plume modelling is a key tool for quantification of potential impacts to inform the EIA process. There are, however, significant uncertainties associated with the modelling at the EIA stage when both dredging methodology and schedule are likely to be a guess at best as the dredging contrac...

  20. The composition of mantle plumes and the deep Earth

    Science.gov (United States)

    Hastie, Alan R.; Fitton, J. Godfrey; Kerr, Andrew C.; McDonald, Iain; Schwindrofska, Antje; Hoernle, Kaj

    2016-06-01

    Determining the composition and geochemical diversity of Earth's deep mantle and subsequent ascending mantle plumes is vital so that we can better understand how the Earth's primitive mantle reservoirs initially formed and how they have evolved over the last 4.6 billion years. Further data on the composition of mantle plumes, which generate voluminous eruptions on the planet's surface, are also essential to fully understand the evolution of the Earth's hydrosphere and atmosphere with links to surface environmental changes that may have led to mass extinction events. Here we present new major and trace element and Sr-Nd-Pb-Hf isotope data on basalts from Curacao, part of the Caribbean large igneous province. From these and literature data, we calculate combined major and trace element compositions for the mantle plumes that generated the Caribbean and Ontong Java large igneous provinces and use mass balance to determine the composition of the Earth's lower mantle. Incompatible element and isotope results indicate that mantle plumes have broadly distinctive depleted and enriched compositions that, in addition to the numerous mantle reservoirs already proposed in the literature, represent large planetary-scale geochemical heterogeneity in the Earth's deep mantle that are similar to non-chondritic Bulk Silicate Earth compositions.

  1. Apollo Video Photogrammetry Estimation Of Plume Impingement Effects

    Science.gov (United States)

    Immer, Christopher; Lane, John; Metzger, Philip T.; Clements, Sandra

    2008-01-01

    The Constellation Project's planned return to the moon requires numerous landings at the same site. Since the top few centimeters are loosely packed regolith, plume impingement from the Lander ejects the granular material at high velocities. Much work is needed to understand the physics of plume impingement during landing in order to protect hardware surrounding the landing sites. While mostly qualitative in nature, the Apollo Lunar Module landing videos can provide a wealth of quantitative information using modem photogrammetry techniques. The authors have used the digitized videos to quantify plume impingement effects of the landing exhaust on the lunar surface. The dust ejection angle from the plume is estimated at 1-3 degrees. The lofted particle density is estimated at 10(exp 8)- 10(exp 13) particles per cubic meter. Additionally, evidence for ejection of large 10-15 cm sized objects and a dependence of ejection angle on thrust are presented. Further work is ongoing to continue quantitative analysis of the landing videos.

  2. Global volcanic emissions: budgets, plume chemistry and impacts

    Science.gov (United States)

    Mather, T. A.

    2012-12-01

    Over the past few decades our understanding of global volcanic degassing budgets, plume chemistry and the impacts of volcanic emissions on our atmosphere and environment has been revolutionized. Global volcanic emissions budgets are needed if we are to make effective use of regional and global atmospheric models in order to understand the consequences of volcanic degassing on global environmental evolution. Traditionally volcanic SO2 budgets have been the best constrained but recent efforts have seen improvements in the quantification of the budgets of other environmentally important chemical species such as CO2, the halogens (including Br and I) and trace metals (including measurements relevant to trace metal atmospheric lifetimes and bioavailability). Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents and during electrical discharges in ash-rich volcanic plumes. These reactive trace species have important consequences for gas plume chemistry and impacts, for example, in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate. There are still many challenges and open questions to be addressed in this fascinating area of science.

  3. Base flow and exhaust plume interaction. Part 1: Experimental study

    NARCIS (Netherlands)

    Schoones, M.M.J.; Bannink, W.J.

    1998-01-01

    An experimental study of the flow field along an axi-symmetric body with a single operating exhaust nozzle has been performed in the scope of an investigation on base flow-jet plume interactions. The structure of under-expanded jets in a co-flowing supersonic free stream was described using analytic

  4. Laser ablation plume expansion into an ambient gas

    DEFF Research Database (Denmark)

    Amoruso, S.; Schou, Jørgen; Lunney, J.G.

    2009-01-01

    The use of an ambient gas is a well-established method employed in pulsed laser deposition (PLD) with nanosecond pulses and has been extensively studied in this context. Most of the existing treatments of the plume expansion are tackled by using complex numerical modeling involving specific target...

  5. Turbulent acidic jets and plumes injected into an alkaline environment

    Science.gov (United States)

    Ulpre, Hendrik

    2012-11-01

    The characteristics of a strong acidic turbulent jet or plume injected into an alkaline environment comprising of a weak/strong base are examined theoretically and experimentally. A chemistry model is developed to understand how the pH of a fluid parcel of monoprotic acid changes as it is diluted and reacts with the ambient fluid. A standard fluid model, based on a top-hat model for acid concentration and velocity is used to express how the dilution of acid varies with distance from the point of discharge. These models are applied to estimate the point of neutralisation and the travel time with distance within the jet/plume. An experimental study was undertaken to test the theoretical results. These experiments involved injecting jets or vertical plumes of dilute nitric acid into a large tank containing a variety of base salts dissolved in water. The injected fluid contained litmus indicator dye which showed a change in colour from red to blue close to the point of neutralisation. In order to obtain a range of neutralisation distances, additional basic salts were added to the water to increase its pH buffering capacity. The results are applied to discuss the environmental implications of an acidic jet/plume injected into the sea off the South East coast of Great Britain.

  6. Contaminant plumes containment and remediation focus area. Technology summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    EM has established a new approach to managing environmental technology research and development in critical areas of interest to DOE. The Contaminant Plumes Containment and Remediation (Plumes) Focus Area is one of five areas targeted to implement the new approach, actively involving representatives from basic research, technology implementation, and regulatory communities in setting objectives and evaluating results. This document presents an overview of current EM activities within the Plumes Focus Area to describe to the appropriate organizations the current thrust of the program and developing input for its future direction. The Plumes Focus Area is developing remediation technologies that address environmental problems associated with certain priority contaminants found at DOE sites, including radionuclides, heavy metals, and dense non-aqueous phase liquids (DNAPLs). Technologies for cleaning up contaminants of concern to both DOE and other federal agencies, such as volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), and other organics and inorganic compounds, will be developed by leveraging resources in cooperation with industry and interagency programs.

  7. Cluster Radioactivity

    Science.gov (United States)

    Poenaru, Dorin N.; Greiner, Walter

    One of the rare examples of phenomena predicted before experimental discovery, offers the opportunity to introduce fission theory based on the asymmetric two center shell model. The valleys within the potential energy surfaces are due to the shell effects and are clearly showing why cluster radioactivity was mostly detected in parent nuclei leading to a doubly magic lead daughter. Saddle point shapes can be determined by solving an integro-differential equation. Nuclear dynamics allows us to calculate the half-lives. The following cluster decay modes (or heavy particle radioactivities) have been experimentally confirmed: 14C, 20O, 23F, 22,24-26Ne, 28,30Mg, 32,34Si with half-lives in good agreement with predicted values within our analytical superasymmetric fission model. The preformation probability is calculated as the internal barrier penetrability. An universal curve is described and used as an alternative for the estimation of the half-lives. The macroscopic-microscopic method was extended to investigate two-alpha accompanied fission and true ternary fission. The methods developed in nuclear physics are also adapted to study the stability of deposited atomic clusters on the planar surfaces.

  8. Bubbles generated from wind-steepened breaking waves: 2. Bubble plumes, bubbles, and wave characteristics

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G.de

    2006-01-01

    Measurements of breaking-wave-generated bubble plumes were made in fresh (but not clean) water in a large wind-wave tunnel. To preserve diversity, a classification scheme was developed on the basis of plume dimensions and "optical density," or the plume's ability to obscure the background. Optically

  9. 76 FR 2112 - Peach Orchard Road Groundwater Plume Site, Augusta, Richmond County, GA; Notice of Settlement

    Science.gov (United States)

    2011-01-12

    ... AGENCY Peach Orchard Road Groundwater Plume Site, Augusta, Richmond County, GA; Notice of Settlement... costs concerning the Peach Orchard Road Groundwater Plume Site located in Augusta, Richmond County... Site name Peach Orchard Road Groundwater Plume Superfund Site by one of the following methods: http...

  10. Heat and mass transfer in the mushroom-shaped head of mantle plume

    Directory of Open Access Journals (Sweden)

    Kirdyashkin Anatoly

    2017-01-01

    Full Text Available The results of experimental and theoretical modeling of free-convection flows in the melt of the plume conduit and in the mushroom-shaped head are presented. It was shown that the plumes with the mushroom-shaped heads can be responsible for the batholith formation. The main parameters of such plumes are estimated.

  11. A parameter model for dredge plume sediment source terms

    Science.gov (United States)

    Decrop, Boudewijn; De Mulder, Tom; Toorman, Erik; Sas, Marc

    2017-01-01

    The presented model allows for fast simulations of the near-field behaviour of overflow dredging plumes. Overflow dredging plumes occur when dredging vessels employ a dropshaft release system to discharge the excess sea water, which is pumped into the trailing suction hopper dredger (TSHD) along with the dredged sediments. The fine sediment fraction in the loaded water-sediment mixture does not fully settle before it reaches the overflow shaft. By consequence, the released water contains a fine sediment fraction of time-varying concentration. The sediment grain size is in the range of clays, silt and fine sand; the sediment concentration varies roughly between 10 and 200 g/l in most cases, peaking at even higher value with short duration. In order to assess the environmental impact of the increased turbidity caused by this release, plume dispersion predictions are often carried out. These predictions are usually executed with a large-scale model covering a complete coastal zone, bay, or estuary. A source term of fine sediments is implemented in the hydrodynamic model to simulate the fine sediment dispersion. The large-scale model mesh resolution and governing equations, however, do not allow to simulate the near-field plume behaviour in the vicinity of the ship hull and propellers. Moreover, in the near-field, these plumes are under influence of buoyancy forces and air bubbles. The initial distribution of sediments is therefore unknown and has to be based on crude assumptions at present. The initial (vertical) distribution of the sediment source is indeed of great influence on the final far-field plume dispersion results. In order to study this near-field behaviour, a highly-detailed computationally fluid dynamics (CFD) model was developed. This model contains a realistic geometry of a dredging vessel, buoyancy effects, air bubbles and propeller action, and was validated earlier by comparing with field measurements. A CFD model requires significant simulation times

  12. Plumes and Earth's Dynamic History : from Core to Biosphere

    Science.gov (United States)

    Courtillot, V. E.

    2002-12-01

    The last half century has been dominated by the general acceptance of plate tectonics. Although the plume concept emerged early in this story, its role has remained ambiguous. Because plumes are singularities, both in space and time, they tend to lie dangerously close to catastrophism, as opposed to the calm uniformitarian view of plate tectonics. Yet, it has become apparent that singular events and transient phenomena are of great importance, even if by definition they cover only a small fraction of geological time, in diverse observational and theoretical fields such as 1) magnetic reversals and the geodynamo, 2) tomography and mantle convection, 3) continental rifting and collision, and 4) evolution of the fluid envelopes (atmospheric and oceanic "climate"; evolution of species in the biosphere). I will emphasize recent work on different types of plumes and on the correlation between flood basalts and mass extinctions. The origin of mantle plumes remains a controversial topic. We suggest that three types of plumes exist, which originate at the three main discontinuities in the Earth's mantle (base of lithosphere, transition zone and core-mantle boundary). Most of the hotspots are short lived (~ 10Ma) and seem to come from the transition zone or above. Important concentrations occur above the Pacific and African superswells. Less than 10 hotspots have been long lived (~ 100Ma) and may have a very deep origin. In the last 50 Ma, these deep-seated plumes in the Pacific and Indo-Atlantic hemispheres have moved slowly, but motion was much faster prior to that. This change correlates with major episodes of true polar wander. The deeper ("primary") plumes are thought to trace global shifts in quadrupolar convection in the lower mantle. These are the plumes that were born as major flood basalts or oceanic plateaus (designated as large igneous provinces or LIPs). Most have an original volume on the order or in excess of 2.5 Mkm3. In most provinces, volcanism lasted on

  13. Pb - Isotopes and Pulses of the Deccan Plume

    Science.gov (United States)

    Basu, A. R.; Yannopoulos, A. S.

    2015-12-01

    Mantle plumes are generally implicated for flood basalt generation in both continental and oceanic environments by impact of large plume heads beneath or within the lithosphere. The Deccan and Siberian flood basalt eruptions, synchronous with the Cretaceous-Paleogene and end-Permian extinctions, respectively, continue to fascinate geoscientists in search for the "kill-mechanisms" by impacts, volcanisms or both. Recently, Richards et al. (2015) proposed that bulk of the Deccan eruption was triggered by the Chicxulub impact. We showed (Basu et al., 1993) that early (68.5 Ma) and late (65 Ma) alkalic pulses of the Deccan were before and after the impact event at 66 Ma. Here, we focus on an extensive volcano-stratigraphic study of Pb isotopic systematics of 69 basaltic samples from 3 subgroups and 12 formations of the Deccan, each sampled from bottom to top along the stratigraphic section, covering the 3km thick 12 Deccan formations. Pb is sensitive to crustal contamination of mantle plume-derived magmas as both the upper and lower mantle are low in Pb (0.02 - 0.15 ppm) compared to ~ 4 ppm in continental crust. The lower Deccan formations of Kalsubai and Lonavala have initial 206Pb/204Pb with a widely varying range (16.543 - 22.823) indicating continental crustal contamination. In contrast, the upper formations of the Wai subgroup show a narrow range of 16.883 to 18.956, reflecting the plume signature. In addition, the 206Pb/204Pb and 207Pb/204Pb data of the Kalsubai subgroup lavas give an isochron age of 2603±140 Ma (single-stage, µ = 8). The Wai subgroup shows a narrow and restricted Pb isotopic range plotting closer to the Geochron. We interpret these data to infer that the basement rocks of the Deccan, the Archean Indian craton, were assimilated by the upwelling melt, ultimately clearing the conduit passages for the lavas sourced from direct melting of the plume head.

  14. Mapping of plume deposits and surface composition on Enceladus

    Science.gov (United States)

    Nordheim, T. A.; Scipioni, F.; Cruikshank, D. P.; Clark, R. N.,; Hand, K. P.

    2017-01-01

    A major result of the Cassini mission was the discovery that the small mid-sized moon Enceladus is presently geological active[Dougherty et al., 2006; Porco et al., 2006; Spencer et al., 2006; Hansen et al., 2008]. This activity results in plumes of water vapor and ice emanating from a series of fractures ("Tiger Stripes") at the moon's South Pole. Some fraction of plume material escapes the moon's gravity and populates the E-ring as well as ultimately providing a source of fresh plasma in the Saturnian magnetosphere [Pontius and Hill, 2006; Kempf et al., 2010]. However, a significant portion of plume material is redeposited on Enceladus and thus provides a source of surface contaminants. By studying the near-infrared spectral signatures of these contaminants we may put new constraints on the composition of the plumes and, ultimately, their source, which is currently believed to be Enceladus's global sub-surface ocean [Iess et al., 2014]. Here we present preliminary results from our analysis of observations from the Visual and Infrared Mapping Spectrometer (VIMS) [Brown et al., 2005] onboard Cassini and mapping of plume deposits across the surface of Enceladus. We have investigated the global variation of the water ice Fresnel peak at 3.1 μm, which may be used as an indicator of ice crystallinity [Hansen & McCord, 2004; Jaumann et al., 2008; Newman et al., 2008]. We have also investigated the slope of the 1.11-2.25 μm spectral region, which serves as an indicator of water ice grain size for small grains (< 100 μm) as well as the presence of contaminants [e.g. Filacchione et al., 2010]. Finally, we have identified and mapped an absorption feature centered at 3.25 μm that may be related to organic contaminants, represented by the band depth of the fundamental C-H stretch [e.g. Cruikshank et al., 2014; Scipioni et al., 2014].

  15. Arsenic cycling in hydrocarbon plumes: secondary effects of natural attenuation

    Science.gov (United States)

    Cozzarelli, Isabelle M.; Schreiber, Madeline E.; Erickson, Melinda L.; Ziegler, Brady A.

    2016-01-01

    Monitored natural attenuation is widely applied as a remediation strategy at hydrocarbon spill sites. Natural attenuation relies on biodegradation of hydrocarbons coupled with reduction of electron acceptors, including solid phase ferric iron (Fe(III)). Because arsenic (As) adsorbs to Fe-hydroxides, a potential secondary effect of natural attenuation of hydrocarbons coupled with Fe(III) reduction is a release of naturally occurring As to groundwater. At a crude-oil-contaminated aquifer near Bemidji, Minnesota, anaerobic biodegradation of hydrocarbons coupled to Fe(III) reduction has been well documented. We collected groundwater samples at the site annually from 2009 to 2013 to examine if As is released to groundwater and, if so, to document relationships between As and Fe inside and outside of the dissolved hydrocarbon plume. Arsenic concentrations in groundwater in the plume reached 230 µg/L, whereas groundwater outside the plume contained less than 5 µg/L As. Combined with previous data from the Bemidji site, our results suggest that (1) naturally occurring As is associated with Fe-hydroxides present in the glacially derived aquifer sediments; (2) introduction of hydrocarbons results in reduction of Fe-hydroxides, releasing As and Fe to groundwater; (3) at the leading edge of the plume, As and Fe are removed from groundwater and retained on sediments; and (4) downgradient from the plume, patterns of As and Fe in groundwater are similar to background. We develop a conceptual model of secondary As release due to natural attenuation of hydrocarbons that can be applied to other sites where an influx of biodegradable organic carbon promotes Fe(III) reduction.

  16. Development of a GNSS Volcano Ash Plume Detector

    Science.gov (United States)

    Rainville, N.; Palo, S. E.; Larson, K. M.; Naik, S. R.

    2015-12-01

    Global Navigation Satellite Systems (GNSS), broadcast signals continuously from mid Earth orbit at a frequency near 1.5GHz. Of the four GNSS constellations, GPS and GLONASS are complete with more than 55 satellites in total. While GNSS signals are intended for navigation and timing, they have also proved to be useful for remote sensing applications. Reflections of the GNSS signals have been used to sense soil moisture, snow depth, and wind speed while refraction of the signals through the atmosphere has provided data on the electron density in the ionosphere as well as water vapor and temperature in the troposphere. Now analysis at the University of Colorado has shown that the attenuation of GNSS signals by volcanic ash plumes can be used to measure the presence and structure of the ash plume. This discovery is driving development of a distributed GNSS sensor network to complement existing optical and radar based ash plume monitoring systems. A GNSS based sensing system operating in L-band is unaffected by weather conditions or time of day. Additionally, the use of an existing signal source greatly reduces the per sensor cost and complexity compared to a radar system. However since any one measurement using this method provides only the total attenuation between the GNSS satellite and the receiver, full tomographic imaging of a plume requires a large number of sensors observing over a diversity of geometries. This presentation will provide an overview of the ongoing development of the GNSS sensor system. Evaluation of low priced commercial GNSS receivers will be discussed, as well as details on the inter sensor network. Based on analysis of existing GPS receivers near volcanic vents, the baseline configuration for an ash plume monitoring network is a 1km spaced ring of receivers 5km from the vent updating every 5 seconds. Preliminary data from field tests will be presented to show the suitability of the sensor system for this configuration near an active volcano.

  17. Plume spectrometry for liquid rocket engine health monitoring

    Science.gov (United States)

    Powers, William T.; Sherrell, F. G.; Bridges, J. H., III; Bratcher, T. W.

    1988-01-01

    An investigation of Space Shuttle Main Engine (SSME) testing failures identified optical events which appeared to be precursors of those failures. A program was therefore undertaken to detect plume trace phenomena characteristic of the engine and to design a monitoring system, responsive to excessive activity in the plume, capable of delivering a warning of an anomalous condition. By sensing the amount of extraneous material entrained in the plume and considering engine history, it may be possible to identify wearing of failing components in time for a safe shutdown and thus prevent a catastrophic event. To investigate the possibilities of safe shutdown and thus prevent a monitor to initiate the shutdown procedure, a large amount of plume data were taken from SSME firings using laboratory instrumentation. Those data were used to design a more specialized instrument dedicated to rocket plume diagnostics. The spectral wavelength range of the baseline data was about 220 nanometers (nm) to 15 micrometer with special attention given to visible and near UV. The data indicates that a satisfactory design will include a polychromator covering the range of 250 nM to 1000 nM, along with a continuous coverage spectrometer, each having a resolution of at least 5A degrees. The concurrent requirements for high resolution and broad coverage are normally at odds with one another in commercial instruments, therefore necessitating the development of special instrumentation. The design of a polychromator is reviewed herein, with a detailed discussion of the continuous coverage spectrometer delayed to a later forum. The program also requires the development of applications software providing detection, variable background discrimination, noise reduction, filtering, and decision making based on varying historical data.

  18. Bubble plumes generated during recharge of basaltic magma reservoirs

    Science.gov (United States)

    Phillips, Jeremy C.; Woods, Andrew W.

    2001-03-01

    CO 2 is relatively insoluble in basaltic magma at low crustal pressures. It therefore exists as a gas phase in the form of bubbles in shallow crustal reservoirs. Over time these bubbles may separate gravitationally from the magma in the chamber. As a result, any new magma which recharges the chamber from deeper in the crust may be more bubble-rich and hence of lower density than the magma in the chamber. Using scaling arguments, we show that for typical recharge fluxes, such a source of low-viscosity, bubble-rich basalt may generate a turbulent bubble plume within the chamber. We also show that the bubbles are typically sufficiently small to have a low Reynolds number and to remain in the flow. We then present a series of analogue laboratory experiments which identify that the motion of such a turbulent bubble-driven line plume is well described by the classical theory of buoyant plumes. Using the classical plume theory we then examine the effect of the return flow associated with such bubble plumes on the mixing and redistribution of bubbles within the chamber. Using this model, we show that a relatively deep bubbly layer of magma may form below a thin foam layer at the roof. If, as an eruption proceeds, there is a continuing influx at the base of the chamber, then our model suggests that the bubble content of the bubbly layer may gradually increase. This may lead to a transition from lava flow activity to more explosive fire-fountaining activity. The foam layer at the top of the chamber may provide a flux for the continual outgassing from the flanks of the volcano [Ryan, Am. Geophys. Union Geophys. Monogr. 91 (1990)] and if it deepens sufficiently it may contribute to the eruptive activity [Vergniolle and Jaupart, J. Geophys. Res. 95 (1990) 2793-3001].

  19. Delta-proteobacterial SAR324 group in hydrothermal plumes on the South Mid-Atlantic Ridge

    KAUST Repository

    Cao, Huiluo

    2016-03-08

    In the dark ocean, the SAR324 group of Delta-proteobacteria has been associated with a chemolithotrophic lifestyle. However, their electron transport chain for energy generation and information system has not yet been well characterized. In the present study, four SAR324 draft genomes were extracted from metagenomes sampled from hydrothermal plumes in the South Mid-Atlantic Ridge. We describe novel electron transport chain components in the SAR324 group, particularly the alternative complex III, which is involved in energy generation. Moreover, we propose that the C-type cytochrome, for example the C553, may play a novel role in electron transfer, adding to our knowledge regarding the energy generation process in the SAR324 cluster. The central carbon metabolism in the described SAR324 genomes exhibits several new features other than methanotrophy e.g. aromatic compound degradation. This suggests that methane oxidation may not be the main central carbon metabolism component in SAR324 cluster bacteria. The reductive acetyl-CoA pathway may potentially be essential in carbon fixation due to the absence of components from the Calvin-Benson cycle. Our study provides insight into the role of recombination events in shaping the genome of the SAR324 group based on a larger number of repeat regions observed, which has been overlooked thus far.

  20. Optical design of moon-based earth's plasmaspheric extreme ultraviolet imager%月基地球等离子体层极紫外成像仪的光学设计

    Institute of Scientific and Technical Information of China (English)

    陈波; 何飞

    2011-01-01

    According to the 30. 4 nm radiation properties of the earth' s plasmasphere, an earth' s plasmaspheric extreme ultraviolet imaging method based on the moon was researched for the first time. The technical parameters of the extreme ultraviolet imager used in the lunar surface were determined, and its field of view is 15°, angular resolution is 0. 1° and the entrance pupil area is larger than 70 cm2. By combining a single spherical multilayer mirror and a spherical microchannel plate photon counting imaging detector, the extrame ultraviolet imager was designed. The ray tracing of designed extreme ultraviolet imager with multilayer optics was also performed. Results show that the radii of the blur spots are 0. 210, 0. 204, 0. 204, and 0. 207 mm respectively at 0,3,5, and 7. 5°, which are basically identical at different field of views. In woking on the lunar surface, the imager has a visionscope of 15. 0 Re to cover the main body of the earth's plasmasphere and a spatial resolution of 0. 10 RE that can reveal the main details of the earth' s plasmasphere. It provides a high quality imaging method for the observation of earths plasmasphere.%依据地球等离子体层在30.4 nm的辐射特性,首次以月球为观测点进行地球等离子体层极紫外波段成像观测方法研究.确定了在月球表面使用的极紫外成像仪的技术参数,给出了视场角为15°、角分辨率为0.1°、入瞳面积>70 cm2的极紫外成像仪的结构形式,采用单球面多层膜反射镜与球面微通道板光子计数成像探测器相结合的方式设计了极紫外成像仪.对设计的极紫外多层膜光学系统成像仪进行光线追迹,弥散斑半径分别为0.210 mm(0°视场)、0.204 mm(3°视场)、0.204 mm(5°视场)、0.207 mm(7.5°视场),对应的角分辨率为0.08°,弥散斑在不同视场角度基本均匀,其结果满足设计要求.该仪器可在月球表面工作,获得视场范围为15.0 RE,覆盖地球等离子体层主

  1. Recycled crust in the Galápagos Plume source at 70 Ma: Implications for plume evolution

    Science.gov (United States)

    Trela, Jarek; Vidito, Christopher; Gazel, Esteban; Herzberg, Claude; Class, Cornelia; Whalen, William; Jicha, Brian; Bizimis, Michael; Alvarado, Guillermo E.

    2015-09-01

    Galápagos plume-related lavas in the accreted terranes of the Caribbean and along the west coast of Costa Rica and Panama provide evidence on the evolution of the Galápagos mantle plume, specifically its mantle temperature, size and composition of heterogeneities, and dynamics. Here we provide new 40Ar/39Ar ages, major and trace element data, Sr-Nd-Pb isotopic compositions, and high-precision olivine analyses for samples from the Quepos terrane (Costa Rica) to closely examine the transitional phase of the Galápagos Plume from Large Igneous Province (LIP) to ocean island basalt (OIB) forming stages. The new ages indicate that the record of Quepos volcanism began at 70 Ma and persisted for 10 Ma. Petrological evidence suggests that the maximum mantle potential temperature (Tp) of the plume changed from ∼1650° to ∼1550 °C between 90-70 Ma. This change correlates with a dominant pyroxenite component in the Galapagos source as indicated by high Ni and Fe/Mn and low Ca olivines relative to those that crystallized in normal peridotite derived melts. The decrease in Tp also correlates with an increase in high-field strength element enrichments, e.g., Nb/Nb*, of the erupted lavas. Radiogenic isotope ratios (Nd-Pb) suggest that the Quepos terrane samples have intermediate (Central Domain) radiogenic signatures. The Galápagos plume at 70 Ma represents elevated pyroxenite melt productivity relative to peridotite in a cooling lithologically heterogeneous mantle.

  2. Energy balance of a laser ablation plume expanding in a background gas

    DEFF Research Database (Denmark)

    Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

    2010-01-01

    The energy balance of a laser ablation plume in an ambient gas for nanosecond pulses has been investigated on the basis of the model of Predtechensky and Mayorov (PM), which provides a relatively simple and clear description of the essential hydrodynamics. This approach also leads to an insightful...... description in dimensionless units of how the initial kinetic energy of the plume is dissipated into kinetic and thermal energy of the background gas. Eventually when the plume has stopped, the initial kinetic energy of the plume is converted into thermal energy of the plume and background gas....

  3. Monitoring the Amazon plume northwestward transport along Lagrangian pathways

    Science.gov (United States)

    Fournier, Severine; Gaultier, Lucile; Vandemark, Douglas; Lee, Tong; Gierach, Michelle

    2016-04-01

    Large rivers are important to marine air-sea interactions and local biogeochemistry. By modifying the local and regional sea surface salinity (SSS), the freshwater inputs associated with major river plumes cause the formation of a layer near the surface with salinity stratification but near-uniform temperature, known as the barrier layer (BL). The BL prevent exchanges between the warm mixed layer and the cold ocean interior, and thus affect the vertical mixing of heat between the mixed layer and the thermocline. This can have an important impact on air-sea interactions such as hurricanes intensification. Our study focuses on the Amazon and Orinoco rivers, respectively the first and fourth world's largest rivers in terms of discharge. Amazon-Orinoco waters are carried northwestward by the North Brazilian Current (NBC) during the first part of the year and then eastward along the North Equatorial Counter Current. The hurricane season in the tropical Atlantic extends from June through November, the period of Amazon-Orinoco plume maximum northwestward extension, on a hurricane route. Being able to monitor the spatial and temporal dispersal of the Amazon and Orinoco river plumes is therefore important to better understand their impact on barrier layer thickness and SST variation at seasonal to interannual time scales. Variations from year to year in spatial extent of the plume may result from several processes including changes in Amazon discharge, ocean advection, turbulent mixing, and wind field. Satellite remote sensing data provide several means to visualize the surface dispersal of the Amazon plume, with ocean color data being the first to track it in the tropical Atlantic ocean further than 1000 km from shore. With the launches of the ESA Soil Moisture and Ocean Salinity (SMOS) and the NASA Aquarius/SAC-D missions, we are now able to use the SSS observations in combination with ocean color, altimetry and sea surface temperature observations to track surface plume

  4. Repeat ridge jumps associated with plume-ridge interaction, melt transport, and ridge migration

    Science.gov (United States)

    Mittelstaedt, Eric; Ito, Garrett; van Hunen, Jeroen

    2011-01-01

    Repeated shifts, or jumps, of mid-ocean ridge segments toward nearby hot spots can produce large, long-term changes to the geometry and location of the tectonic plate boundaries. Ridge jumps associated with hot spot-ridge interaction are likely caused by several processes including shear on the base of the plate due to expanding plume material as well as reheating of lithosphere as magma passes through it to feed off-axis volcanism. To study how these processes influence ridge jumps, we use numerical models to simulate 2-D (in cross section) viscous flow of the mantle, viscoplastic deformation of the lithosphere, and melt migration upward from the asthenospheric melting zone, laterally along the base of the lithosphere, and vertically through the lithosphere. The locations and rates that magma penetrates and heats the lithosphere are controlled by the time-varying accumulation of melt beneath the plate and the depth-averaged lithospheric porosity. We examine the effect of four key parameters: magmatic heating rate of the lithosphere, plate spreading rate, age of the seafloor overlying the plume, and the plume-ridge migration rate. Results indicate that the minimum value of the magmatic heating rate needed to initiate a ridge jump increases with plate age and spreading rate. The time required to complete a ridge jump decreases with larger values of magmatic heating rate, younger plate age, and faster spreading rate. For cases with migrating ridges, models predict a range of behaviors including repeating ridge jumps, much like those exhibited on Earth. Repeating ridge jumps occur at moderate magmatic heating rates and are the result of changes in the hot spot magma flux in response to magma migration along the base of an evolving lithosphere. The tendency of slow spreading to promote ridge jumps could help explain the observed clustering of hot spots near the Mid-Atlantic Ridge. Model results also suggest that magmatic heating may significantly thin the lithosphere

  5. Helium, heat, and the generation of hydrothermal event plumes at mid-ocean ridges

    Science.gov (United States)

    Lupton, John E.; Baker, Edward T.; Massoth, Gary J.

    1999-09-01

    Hydrothermal event plumes are unique water-column features observed over mid-ocean ridges, presumably generated by the sudden release of large volumes of hot, buoyant fluid. Although the specifics of event plume generation are unknown, event plumes have been attributed to the rapid emptying of a hydrothermal reservoir or to rapid heat extraction from a recently emplaced dike or seafloor lava flows. The chemical and thermal signatures of event plumes as compared to the underlying steady-state plumes offer important clues to the generation of event plumes. Event plumes have low 3He/heat ratios of ˜0.4 × 10-17 mol J-1, similar to vent fluids from mature hydrothermal systems. In contrast, the steady-state plumes found beneath the event plumes have elevated and variable 3He/heat ratios of 2 to 5 × 10-17 mol J-1. Fluids collected directly over fresh lava flows have even higher 3He/heat ratios of 2 to 8 × 10-17 mol J-1, up to 30 times the event plume values. These disparate 3He/heat ratios place strong constraints on models of event plume generation, especially models which rely on heat extraction from seafloor eruptions. Published by Elsevier Science B.V.

  6. An indigenous cluster beam apparatus with a reflectron time-of-flight mass spectrometer

    Indian Academy of Sciences (India)

    G Raina; G U Kulkarni; R T Yadav; V S Ramamurthy; C N R Rao

    2000-04-01

    The design and fabrication of a Smalley-type cluster source in combination with a reflectron based time-of-flight (TOF) mass spectrometer are reported. The generation of clusters is based on supersonic jet expansion of the sampling plume. Sample cells for both liquid and solid targets developed for this purpose are described. Two pulsed Nd-YAG lasers are used in tandem, one (532 nm) for target vapourization and the other (355 nm) for cluster ionization. Methanol clusters of nuclearity up to 14 (mass 500 amu) were produced from liquid methanol as the test sample. The clusters were detected with a mass resolution of ~ 2500 in the R-TOF geometry. Carbon clusters up to a nuclearity of 28 were obtained using a polyimide target. The utility of the instrument is demonstrated by carrying out experiments to generate mixed clusters from alcohol mixtures.

  7. Laser ablation synthesis of zinc oxide clusters: a new family of fullerenes?

    CERN Document Server

    Bulgakov, A V; Bulgakov, Alexander V.; Ozerov, Igor; Proxy, Wladimir Marine; ccsd-00000864, ccsd

    2003-01-01

    Positively charged zinc oxide clusters ZnnOm (up to n = 16, m <= n) of various stoichiometry were synthesized in the gas phase by excimer ArF laser ablation of a ZnO target and investigated using time-of-flight mass spectrometry. Depending on ablation conditions, either metal rich or stoichiometric clusters dominate in the mass spectrum. When the irradiated target surface is fairly fresh, the most abundant clusters are metal rich with Zn(n+1)On and Zn(n+3)On being the major series. The stoichiometric clusters are observed with an etched ablated surface. The magic numbers at n = 9, 11 and 15 in mass spectra of (ZnO)n clusters indicate that the clusters have hollow spheroid structures related to fullerenes. A local abundance minimum at n = 13 provides an additional evidence for the presence in the ablation plume of fullerene-like (ZnO)n clusters.

  8. Development of dominant sequence characterized amplified region (SCAR marker linked with plume moth (Exelastis atomosa Walsingham 1886 resistance in pigeon-pea

    Directory of Open Access Journals (Sweden)

    Ramya R Mishra

    2015-12-01

    Full Text Available The mode of gene action governing resistance to plume moth (Exelastis atomosa Walsingham 1886 derived from pigeon-pea (Cajanus scarabaeoides (L. Thouars accession ICPW-94 has been determined and the resistance alleles have been designated as PPM1. The progenies of F2 population and F3 families derived from an interspecific cross C. cajan (L. Huth ('ICP-26' x C. scarabaeoides (accession ICPW-94 revealed monogenic gene action for resistance to plume moth, and the dominant control by single locus or cluster of tightly linked alleles. Bulked segregant analysis (BSA of 116 F2 progenies by using 143 parental polymorphic RAPD primers could identify a fragment OPA09(910 associated with plume moth resistance in coupling phase of linkage. Further single plant analysis of the 116 F2 mapping population revealed OPA09(910 was linked to PPMi locus conferring host resistance to plume moth with recombination fraction (rf value of 0.125 (12.7 cM of Kosambi function. The resistance specific fragment OPA09(910 was cloned, sequenced and converted into a sequence characterized amplified region (SCAR marker, SCOPA09(942, which was also closely associated (10.3 cM with the locus PPMl with rf value 0.102. BLAST analysis with pigeon-pea genome sequence also confirmed its occurrence in CcLG02 (Scafseq.LG_V5.0fa and contig 01597 (AFSP01.fsa1. This SCAR marker showed reasonable screening efficiency in the F2, F3, and BC1F1 lines, thus it can be used as genetic handle in marker-assisted introgression of the genomic fragment conferring plume moth resistance and screening of breeding lines in pigeon-pea.

  9. Gaseous ion-composition measurements in the young exhaust plume of jet aircraft at cruising altitudes. Implications for aerosols and gaseous sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, F.; Wohlfrom, K.H.; Klemm, M.; Schneider, J.; Gollinger, K. [Max-Planck-Inst. for Nuclear Physics, Heidelberg (Germany); Schumann, U.; Busen, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    Mass spectrometric measurements were made in the young exhaust plume of an Airbus (A310) at cruising altitudes at distances between 400 and 800 m behind the Airbus (averaged plume age: 3.4 sec). The measurements indicate that gaseous sulfuric acid (GSA) number densities were less than 1.3 x 10{sup 8} cm{sup -3} which is smaller than the expected total sulfuric acid. Hence the missing sulfuric acid must have been in the aerosol phase. These measurements also indicate a total aerosol surface area density A{sub T} {<=} 5.4 x 10{sup -5} cm{sup 2} per cm{sup 3} which is consistent with simultaneously measured soot and water contrail particles. However, homogeneous nucleation leading to (H{sub 2}SO{sub 4}){sub x}(H{sub 2}O){sub y}-clusters can not be ruled out. (author) 16 refs.

  10. Towards Simulating Non-Axisymmetric Influences on Aircraft Plumes for Signature Prediction

    Science.gov (United States)

    Kenzakowski, D. C.; Shipman, J. D.; Dash, S. M.

    2000-01-01

    A methodology for efficiently including three-dimensional effects on aircraft plume signature is presented. First, exploratory work on the use of passive mixing enhancement devices, namely chevrons and tabs, in IR signature reduction for external turbofan plumes is demonstrated numerically and experimentally. Such small attachments, when properly designed, cause an otherwise axisymmetric plume to have significant 3D structures, affecting signature prediction. Second, an approach for including non-axisymmetric and installation effects in plume signature prediction is discussed using unstructured methodology. Unstructured flow solvers, using advanced turbulence modeling and plume thermochemistry, facilitate the modeling of aircraft effects on plume structure that previously have been neglected due to gridding complexities. The capabilities of the CRUNCH unstructured Navier-Stokes solver for plume modeling is demonstrated for a passively mixed turbofan nozzle, a generic fighter nozzle, and a complete aircraft.

  11. Wedge Shock and Nozzle Exhaust Plume Interaction in a Supersonic Jet Flow

    Science.gov (United States)

    Castner, Raymond; Zaman, Khairul; Fagan, Amy; Heath, Christopher

    2014-01-01

    Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the nozzle exhaust plume. Aft body shock waves that interact with the exhaust plume contribute to the near-field pressure signature of a vehicle. The plume and shock interaction was studied using computational fluid dynamics and compared with experimental data from a coaxial convergent-divergent nozzle flow in an open jet facility. A simple diamond-shaped wedge was used to generate the shock in the outer flow to study its impact on the inner jet flow. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the opposite plume boundary. The sonic boom pressure signature of the nozzle exhaust plume was modified by the presence of the wedge. Both the experimental results and computational predictions show changes in plume deflection.

  12. The impact of glacier geometry on meltwater plume structure and submarine melt in Greenland fjords

    Science.gov (United States)

    Carroll, D.; Sutherland, D. A.; Hudson, B.; Moon, T.; Catania, G. A.; Shroyer, E. L.; Nash, J. D.; Bartholomaus, T. C.; Felikson, D.; Stearns, L. A.; Noël, B. P. Y.; Broeke, M. R.

    2016-09-01

    Meltwater from the Greenland Ice Sheet often drains subglacially into fjords, driving upwelling plumes at glacier termini. Ocean models and observations of submarine termini suggest that plumes enhance melt and undercutting, leading to calving and potential glacier destabilization. Here we systematically evaluate how simulated plume structure and submarine melt during summer months depends on realistic ranges of subglacial discharge, glacier depth, and ocean stratification from 12 Greenland fjords. Our results show that grounding line depth is a strong control on plume-induced submarine melt: deep glaciers produce warm, salty subsurface plumes that undercut termini, and shallow glaciers produce cold, fresh surface-trapped plumes that can overcut termini. Due to sustained upwelling velocities, plumes in cold, shallow fjords can induce equivalent depth-averaged melt rates compared to warm, deep fjords. These results detail a direct ocean-ice feedback that can affect the Greenland Ice Sheet.

  13. An Automatic Clustering Technique for Optimal Clusters

    CERN Document Server

    Pavan, K Karteeka; Rao, A V Dattatreya; 10.5121/ijcsea.2011.1412

    2011-01-01

    This paper proposes a simple, automatic and efficient clustering algorithm, namely, Automatic Merging for Optimal Clusters (AMOC) which aims to generate nearly optimal clusters for the given datasets automatically. The AMOC is an extension to standard k-means with a two phase iterative procedure combining certain validation techniques in order to find optimal clusters with automation of merging of clusters. Experiments on both synthetic and real data have proved that the proposed algorithm finds nearly optimal clustering structures in terms of number of clusters, compactness and separation.

  14. Observing Volcanic Plumes Using Singular Vector Decomposition of MIPAS Spectra

    Science.gov (United States)

    Smith, Andrew J. A.; Dudhia, A.; Grainger, R. G.

    2012-11-01

    A simple flagging of MIPAS spectra based on ratios of radiances in a narrow section of the A-Band (685-970 cm-1) can mark suspected volcanic plumes when their signal is strong and uncontaminated, but is not hugely sensitive to weaker signals. Using singular vector decomposition (SVD) to remove modes of spectral variability due to normal atmospheric conditions, a more accurate indicator of volcanic ash plumes in the Oxford MIPAS cloud retrieval can be obtained. As time progresses, the strength of the signal can fall off, but it is still possible to be tracked. SVD also allows one to obtain information about the spectral signature of a specific eruption. Since individual events have different signatures, once a training set has been obtained, signals from different events can be distinguished.

  15. Modelling the plasma plume of an assist source in PIAD

    Science.gov (United States)

    Wauer, Jochen; Harhausen, Jens; Foest, Rüdiger; Loffhagen, Detlef

    2016-09-01

    Plasma ion assisted deposition (PIAD) is a technique commonly used to produce high-precision optical interference coatings. Knowledge regarding plasma properties is most often limited to dedicated scenarios without film deposition. Approaches have been made to gather information on the process plasma in situ to detect drifts which are suspected to cause limits in repeatability of resulting layer properties. Present efforts focus on radiance monitoring of the plasma plume of an Advanced Plasma Source (APSpro, Bühler) by optical emission spectroscopy to provide the basis for an advanced plasma control. In this contribution modelling results of the plume region are presented to interpret these experimental data. In the framework of the collisional radiative model used, 15 excited neutral argon states in the plasma are considered. Results of the species densities show good consistency with the measured optical emission of various argon 2 p - 1 s transitions. This work was funded by BMBF under grant 13N13213.

  16. An experimental study of starting plumes over area sources

    Energy Technology Data Exchange (ETDEWEB)

    Friedl, M.J.; Haertel, C.; Fannelop, T.K. [Swiss Federal Institute of Technology, Zuerich (Switzerland). Inst. of Fluid Dynamics

    1999-12-01

    Experiments have been performed to study the dynamics of plumes which develop, if buoyant fluid enters a homogeneous, unstratified environment through a source of finite width. The experiments were conducted in a cubic tank of salt water with 0.8 m side length into which dyes fresh water was released at a constant volume-flow rate through a circular felt at the bottom. The governing non-dimensional parameter of the flow, namely the ratio of inflow velocity to buoyancy velocity, was varied over more than two orders of magnitude in the experiments. The flow is shown to pass through two distinct phases, and a new integral model is presented which describes the flow in the early stage. For later times and at larger distances from the source, the flow is found to be well described by Turner's model for starting plumes from point sources.

  17. PLUMED 2: New feathers for an old bird

    CERN Document Server

    Tribello, Gareth A; Branduardi, Davide; Camilloni, Carlo; Bussi, Giovanni

    2014-01-01

    Enhancing sampling and analyzing simulations are central issues in molecular simulation. Recently, we introduced PLUMED, an open-source plug-in that provides some of the most popular molecular dynamics (MD) codes with implementations of a variety of different enhanced sampling algorithms and collective variables (CVs). The rapid changes in this field, in particular new directions in enhanced sampling and dimensionality reduction together with new hardwares, require a code that is more flexible and more efficient. We therefore present PLUMED 2 here - a complete rewrite of the code in an object-oriented programming language (C++). This new version introduces greater flexibility and greater modularity, which both extends its core capabilities and makes it far easier to add new methods and CVs. It also has a simpler interface with the MD engines and provides a single software library containing both tools and core facilities. Ultimately, the new code better serves the ever-growing community of users and contribut...

  18. An expert system for spectroscopic analysis of rocket engine plumes

    Science.gov (United States)

    Reese, Greg; Valenti, Elizabeth; Alphonso, Keith; Holladay, Wendy

    The expert system described in this paper analyzes spectral emissions of rocket engine exhaust plumes and shows major promise for use in engine health diagnostics. Plume emission spectroscopy is an important tool for diagnosing engine anomalies, but it is time-consuming and requires highly skilled personnel. The expert system was created to alleviate such problems. The system accepts a spectral plot in the form of wavelength vs intensity pairs and finds the emission peaks in the spectrum, lists the elemental emitters present in the data and deduces the emitter that produced each peak. The system consists of a conventional language component and a commercially available inference engine that runs on an Apple Macintosh computer. The expert system has undergone limited preliminary testing. It detects elements well and significantly decreases analysis time.

  19. Distributed Plume Source Localization Using Hierarchical Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    KUANG Xing-hong; LIU Yu-qing; WU Yan-xiang; SHAO Hui-he

    2009-01-01

    A hierarchical wireless sensor networks (WSN) was proposed to estimate the plume source location. Such WSN can be of tremendous help to emergency personnel trying to protect people from terrorist attacks or responding to an accident. The entire surveillant field is divided into several small sub-regions. In each sub-region, the localization algorithm based on the improved particle filter (IPF) was performed to estimate the location. Some improved methods such as weighted centroid, residual resampling were introduced to the IPF algorithm to increase the localization performance. This distributed estimation method elirninates many drawbacks inherent with the traditional centralized optimization method. Simulation results show that localization algorithm is efficient far estimating the plume source location.

  20. Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

    CERN Document Server

    Choi, David S; Vasavada, Ashwin R; Simon-Miller, Amy A

    2013-01-01

    We present an updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are quasi-stable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact...

  1. Similarity scaling of surface-released smoke plumes

    DEFF Research Database (Denmark)

    Mikkelsen, T.; Ejsing Jørgensen, Hans; Nielsen, M.

    2002-01-01

    Concentration fluctuation data from surface-layer released smoke plumes have been investigated with the purpose of finding suitable scaling parameters for the corresponding two-particle, relative diffusion process. Dispersion properties have been measured at downwind ranges between 0.1 and 1 km...... from a continuous, neutrally buoyant ground level source. A combination of SF6 and chemical smoke (aerosols) was used as tracer. Instantaneous crosswind concentration profiles of high temporal (up to 55 Hz) and spatial resolution (down to 0.375 m) were obtained from aerosol-backscatter Lidar detection...... and duration statistics. The diffusion experiments were accompanied by detailed in-situ micrometeorological mean and turbulence measurements. In this paper, a new distance-neighbour function for surface-released smoke plumes is proposed, accompanied by experimental evidence in its support. The new distance...

  2. Agent-Based Chemical Plume Tracing Using Fluid Dynamics

    Science.gov (United States)

    Zarzhitsky, Dimitri; Spears, Diana; Thayer, David; Spears, William

    2004-01-01

    This paper presents a rigorous evaluation of a novel, distributed chemical plume tracing algorithm. The algorithm is a combination of the best aspects of the two most popular predecessors for this task. Furthermore, it is based on solid, formal principles from the field of fluid mechanics. The algorithm is applied by a network of mobile sensing agents (e.g., robots or micro-air vehicles) that sense the ambient fluid velocity and chemical concentration, and calculate derivatives. The algorithm drives the robotic network to the source of the toxic plume, where measures can be taken to disable the source emitter. This work is part of a much larger effort in research and development of a physics-based approach to developing networks of mobile sensing agents for monitoring, tracking, reporting and responding to hazardous conditions.

  3. Volcanic tremor and plume height hysteresis from Pavlof Volcano, Alaska.

    Science.gov (United States)

    Fee, David; Haney, Matthew M; Matoza, Robin S; Eaton, Alexa R; Cervelli, Peter; Schneider, David J; Iezzi, Alexandra M

    2017-01-06

    The March 2016 eruption of Pavlof Volcano, Alaska, produced an ash plume that caused the cancellation of more than 100 flights in North America. The eruption generated strong tremor that was recorded by seismic and remote low-frequency acoustic (infrasound) stations, including the EarthScope Transportable Array. The relationship between the tremor amplitudes and plume height changes considerably between the waxing and waning portions of the eruption. Similar hysteresis has been observed between seismic river noise and discharge during storms, suggesting that flow and erosional processes in both rivers and volcanoes can produce irreversible structural changes that are detectable in geophysical data. We propose that the time-varying relationship at Pavlof arose from changes in the tremor source related to volcanic vent erosion. This relationship may improve estimates of volcanic emissions and characterization of eruption size and intensity.

  4. In-Situ and Remote-Sensing Data Fusion Using Machine Learning Techniques to Infer Urban and Fire Related Pollution Plumes

    Science.gov (United States)

    Russell, P. B.; Segal-Rozenhaimer, M.; Schmid, B.; Redemann, J.; Livingston, J. M.; Flynn, C.J.; Johnson, R. R.; Dunagan, S. E.; Shinozuka, Y.; Kacenelenbogen, M.; Chatfield, R. B.

    2014-01-01

    Airmass type characterization is key in understanding the relative contribution of various emission sources to atmospheric composition and air quality and can be useful in bottom-up model validation and emission inventories. However, classification of pollution plumes from space is often not trivial. Sub-orbital campaigns, such as SEAC4RS (Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) give us a unique opportunity to study atmospheric composition in detail, by using a vast suite of in-situ instruments for the detection of trace gases and aerosols. These measurements allow identification of spatial and temporal atmospheric composition changes due to various pollution plumes resulting from urban, biogenic and smoke emissions. Nevertheless, to transfer the knowledge gathered from such campaigns into a global spatial and temporal context, there is a need to develop workflow that can be applicable to measurements from space. In this work we rely on sub-orbital in-situ and total column remote sensing measurements of various pollution plumes taken aboard the NASA DC-8 during 2013 SEAC4RS campaign, linking them through a neural-network (NN) algorithm to allow inference of pollution plume types by input of columnar aerosol and trace-gas measurements. In particular, we use the 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) airborne measurements of wavelength dependent aerosol optical depth (AOD), particle size proxies, O3, NO2 and water vapor to classify different pollution plumes. Our method relies on assigning a-priori ground-truth labeling to the various plumes, which include urban pollution, different fire types (i.e. forest and agriculture) and fire stage (i.e. fresh and aged) using cluster analysis of aerosol and trace-gases in-situ and auxiliary (e.g. trajectory) data and the training of a NN scheme to fit the best prediction parameters using 4STAR measurements as input. We explore our

  5. Second order closure modeling of turbulent buoyant wall plumes

    Science.gov (United States)

    Zhu, Gang; Lai, Ming-Chia; Shih, Tsan-Hsing

    1992-01-01

    Non-intrusive measurements of scalar and momentum transport in turbulent wall plumes, using a combined technique of laser Doppler anemometry and laser-induced fluorescence, has shown some interesting features not present in the free jet or plumes. First, buoyancy-generation of turbulence is shown to be important throughout the flow field. Combined with low-Reynolds-number turbulence and near-wall effect, this may raise the anisotropic turbulence structure beyond the prediction of eddy-viscosity models. Second, the transverse scalar fluxes do not correspond only to the mean scalar gradients, as would be expected from gradient-diffusion modeling. Third, higher-order velocity-scalar correlations which describe turbulent transport phenomena could not be predicted using simple turbulence models. A second-order closure simulation of turbulent adiabatic wall plumes, taking into account the recent progress in scalar transport, near-wall effect and buoyancy, is reported in the current study to compare with the non-intrusive measurements. In spite of the small velocity scale of the wall plumes, the results showed that low-Reynolds-number correction is not critically important to predict the adiabatic cases tested and cannot be applied beyond the maximum velocity location. The mean and turbulent velocity profiles are very closely predicted by the second-order closure models. but the scalar field is less satisfactory, with the scalar fluctuation level underpredicted. Strong intermittency of the low-Reynolds-number flow field is suspected of these discrepancies. The trends in second- and third-order velocity-scalar correlations, which describe turbulent transport phenomena, are also predicted in general, with the cross-streamwise correlations better than the streamwise one. Buoyancy terms modeling the pressure-correlation are shown to improve the prediction slightly. The effects of equilibrium time-scale ratio and boundary condition are also discussed.

  6. Iodine Plasma Species Measurements in a Hall Effect Thruster Plume

    Science.gov (United States)

    2013-04-01

    vary across the plume. Furthermore, ion energy measurements here and historically show non - Maxwellian ion velocity distributions that vary with...related to beam composition or to non -uniformities in the gas flow distribution. Thus, thrust data are not reported...distribution is far from Maxwellian . D. Combined Probe The combined ESA/ExB probe was used to analyze specific populations selected from the ESA data

  7. Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

    Science.gov (United States)

    Choi, David Sanghun; Showman, Adam P.; Vasavada, Ashwin R.; Simon-Miller, Amy A.

    2013-01-01

    We present an updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are relatively cloud-free regions that emit strongly at 5 lm; improved knowledge of these features is crucial for fully understanding Galileo probe measurements taken during its descent through one. Hot spots are quasistable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-like 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. These clouds travel at 150-200 m/s, much faster than the 100 m/s hot spot and plume drift speed. This raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. Most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby wave controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed.

  8. Observations and modeling of a tidal inlet dye tracer plume

    Science.gov (United States)

    Feddersen, Falk; Olabarrieta, Maitane; Guza, R. T.; Winters, D.; Raubenheimer, Britt; Elgar, Steve

    2016-10-01

    A 9 km long tracer plume was created by continuously releasing Rhodamine WT dye for 2.2 h during ebb tide within the southern edge of the main tidal channel at New River Inlet, NC on 7 May 2012, with highly obliquely incident waves and alongshore winds. Over 6 h from release, COAWST (coupled ROMS and SWAN, including wave, wind, and tidal forcing) modeled dye compares well with (aerial hyperspectral and in situ) observed dye concentration. Dye first was transported rapidly seaward along the main channel and partially advected across the ebb-tidal shoal until reaching the offshore edge of the shoal. Dye did not eject offshore in an ebb-tidal jet because the obliquely incident breaking waves retarded the inlet-mouth ebb-tidal flow and forced currents along the ebb shoal. The dye plume largely was confined to <4 m depth. Dye was then transported downcoast in the narrow (few 100 m wide) surfzone of the beach bordering the inlet at 0.3 m s-1 driven by wave breaking. Over 6 h, the dye plume is not significantly affected by buoyancy. Observed dye mass balances close indicating all released dye is accounted for. Modeled and observed dye behaviors are qualitatively similar. The model simulates well the evolution of the dye center of mass, lateral spreading, surface area, and maximum concentration, as well as regional ("inlet" and "ocean") dye mass balances. This indicates that the model represents well the dynamics of the ebb-tidal dye plume. Details of the dye transport pathways across the ebb shoal are modeled poorly perhaps owing to low-resolution and smoothed model bathymetry. Wave forcing effects have a large impact on the dye transport.

  9. Statistical analyses of plume composition and deposited radionuclide mixture ratios

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Terrence D.; Sallaberry, Cedric Jean-Marie; Eckert-Gallup, Aubrey Celia; Brito, Roxanne; Hunt, Brian D.; Osborn, Douglas.

    2014-01-01

    A proposed method is considered to classify the regions in the close neighborhood of selected measurements according to the ratio of two radionuclides measured from either a radioactive plume or a deposited radionuclide mixture. The subsequent associated locations are then considered in the area of interest with a representative ratio class. This method allows for a more comprehensive and meaningful understanding of the data sampled following a radiological incident.

  10. Lithological structure of the Galápagos Plume

    Science.gov (United States)

    Vidito, Christopher; Herzberg, Claude; Gazel, Esteban; Geist, Dennis; Harpp, Karen

    2013-10-01

    We have measured Ni, Ca, and Mn in olivine phenocrysts from volcanoes in the Galápagos Archipelago to infer the mantle source lithologies. Results show that peridotite is the dominant source lithology for Fernandina, Floreana, Genovesa, Wolf Island, and Darwin Island. These volcanoes largely characterize the PLUME, WD, FLO, and DUM Nd, Sr, and Pb isotopic endmembers of Harpp and White (2001). Volcan Wolf, Alcedo, Marchena, and Cerro Azul, also produced from the melting of peridotite sources, have isotopic compositions that can be defined by mixing of the four isotopic endmembers. Our analysis suggests that peridotite was present in the sources of the volcanoes covered in this study and therefore is the dominant source lithology of the Galápagos plume. Pyroxenite melting is generally focused in two isotopically distinct domains: Roca Redonda, Volcan Ecuador, and Sierra Negra in the enriched western part of the archipelago and Santiago, Santa Cruz, and Santa Fe in the depleted east. One implication of this finding is that the Western and Eastern Pyroxenite Domains represent two separate bodies of recycled crust within the Galápagos mantle plume. Furthermore, both isotopically enriched and depleted domains of the archipelago were generated from mixtures of peridotite and pyroxenite. This suggests that there is no relationship between the source lithology of the Galápagos plume and its isotopic characteristics. The identification of peridotite-source melting in volcanoes with isotopic characteristics that have been attributed to recycled crust points to the importance of mixing in OIB genesis, consistent with studies in the Canary Islands.

  11. Looking for life in the plumes of ocean worlds

    Science.gov (United States)

    Lunine, Jonathan; Srama, Ralf; Waite, J. Hunter; Sherwood, Brent; Cable, Morgan; Postberg, Frank; Kempf, Sascha

    2016-07-01

    Interest in searching for life in the outer solar system has intensified recently with the new start of the Europa Multiple Flyby Mission and the insertion through a NASA community announcement of an Ocean Worlds (Titan and Enceladus) theme in the list of admissible New Frontiers Missions. As part of a Discovery proposal called "Enceladus Life Finder", or ELF, a multidisciplinary team of scientists led by the authors developed a set of measurements for determining the habitability of Enceladus' internal ocean and the presence of biological activity therein, obtained by flying two mass spectrometers through Enceladus' plume - one optimized for gas, the other for grains. The measurements and information derived therefrom cut to the heart of what biological activity does that distinguishes it from abiotic processes. They also tightly constrain the essential parameters of ocean habitability including pH, redox state, available free energy, and temperature of any active hydrothermal systems on the floor of the Enceladus ocean. In addition to Enceladus, such a protocol is applicable to Europa should deep-seated plumes be present there, but the much higher gravity requires that the grain mass spectrometer be flown at a very low altitude. On the Europa flyby mission, this would require a small spacecraft that would detach from the main spacecraft and fly within a few kilometers of the surface. Proposed to NASA as Sylph, this simple plume probe would provide a low-cost way to equip the Europa Multiple Flyby Mission to prepare for potential plumes, and use them to determine the habitability and biopotential of the Europan ocean.

  12. Study of Plume Impingement Effects in the Lunar Lander Environment

    Science.gov (United States)

    Marichalar, Jeremiah; Prisbell, A.; Lumpkin, F.; LeBeau, G.

    2010-01-01

    Plume impingement effects from the descent and ascent engine firings of the Lunar Lander were analyzed in support of the Lunar Architecture Team under the Constellation Program. The descent stage analysis was performed to obtain shear and pressure forces on the lunar surface as well as velocity and density profiles in the flow field in an effort to understand lunar soil erosion and ejected soil impact damage which was analyzed as part of a separate study. A CFD/DSMC decoupled methodology was used with the Bird continuum breakdown parameter to distinguish the continuum flow from the rarefied flow. The ascent stage analysis was performed to ascertain the forces and moments acting on the Lunar Lander Ascent Module due to the firing of the main engine on take-off. The Reacting and Multiphase Program (RAMP) method of characteristics (MOC) code was used to model the continuum region of the nozzle plume, and the Direct Simulation Monte Carlo (DSMC) Analysis Code (DAC) was used to model the impingement results in the rarefied region. The ascent module (AM) was analyzed for various pitch and yaw rotations and for various heights in relation to the descent module (DM). For the ascent stage analysis, the plume inflow boundary was located near the nozzle exit plane in a region where the flow number density was large enough to make the DSMC solution computationally expensive. Therefore, a scaling coefficient was used to make the DSMC solution more computationally manageable. An analysis of the effectiveness of this scaling technique was performed by investigating various scaling parameters for a single height and rotation of the AM. Because the inflow boundary was near the nozzle exit plane, another analysis was performed investigating three different inflow contours to determine the effects of the flow expansion around the nozzle lip on the final plume impingement results.

  13. Hall Effect Thruster Plume Contamination and Erosion Study

    Science.gov (United States)

    Jaworske, Donald A.

    2000-01-01

    The objective of the Hall effect thruster plume contamination and erosion study was to evaluate the impact of a xenon ion plume on various samples placed in the vicinity of a Hall effect thruster for a continuous 100 hour exposure. NASA Glenn Research Center was responsible for the pre- and post-test evaluation of three sample types placed around the thruster: solar cell cover glass, RTV silicone, and Kapton(R). Mass and profilometer), were used to identify the degree of deposition and/or erosion on the solar cell cover glass, RTV silicone, and Kapton@ samples. Transmittance, reflectance, solar absorptance, and room temperature emittance were used to identify the degree of performance degradation of the solar cell cover glass samples alone. Auger spectroscopy was used to identify the chemical constituents found on the surface of the exposed solar cell cover glass samples. Chemical analysis indicated some boron nitride contamination on the samples, from boron nitride insulators used in the body of the thruster. However, erosion outweighted contamination. All samples exhibited some degree of erosion. with the most erosion occurring near the centerline of the plume and the least occurring at the +/- 90 deg positions. For the solar cell cover glass samples, erosion progressed through the antireflective coating and into the microsheet glass itself. Erosion occurred in the solar cell cover glass, RTV silicone and Kapton(R) at different rates. All optical properties changed with the degree of erosion, with solar absorptance and room temperature emittance increasing with erosion. The transmittance of some samples decreased while the reflectance of some samples increased and others decreased. All results are consistent with an energetic plume of xenon ions serving as a source for erosion.

  14. Modelling the fate of the Tijuana River discharge plume

    Science.gov (United States)

    van Ormondt, M.; Terrill, E.; Hibler, L. F.; van Dongeren, A. R.

    2010-12-01

    After rainfall events, the Tijuana River discharges excess runoff into the ocean in a highly turbid plume. The runoff waters contain large suspended solids concentrations, as well as high levels of toxic contaminants, bacteria, and hepatitis and enteroviruses. Public health hazards posed by the effluent often result in beach closures for several kilometers northward along the U.S. shoreline. A Delft3D model has been set up to predict the fate of the Tijuana River plume. The model takes into account the effects of tides, wind, waves, salinity, and temperature stratification. Heat exchange with the atmosphere is also included. The model consists of a relatively coarse outer domain and a high-resolution surf zone domain that are coupled with Domain Decomposition. The offshore boundary conditions are obtained from the larger NCOM SoCal model (operated by the US Navy) that spans the entire Southern California Bight. A number of discharge events are investigated, in which model results are validated against a wide range of field measurements in the San Diego Bight. These include HF Radar surface currents, REMUS tracks, drifter deployments, satellite imagery, as well as current and temperature profile measurements at a number of locations. The model is able to reproduce the observed current and temperature patterns reasonably well. Under calm conditions, the model results suggest that the hydrodynamics in the San Diego Bight are largely governed by internal waves. During rainfall events, which are typically accompanied by strong winds and high waves, wind and wave driven currents become dominant. An analysis will be made of what conditions determine the trapping and mixing of the plume inside the surfzone and/or the propagation of the plume through the breakers and onto the coastal shelf. The model is now also running in operational mode. Three day forecasts are made every 24 hours. This study was funded by the Office of Naval Research.

  15. Modeling of Homogeneous Condensation in High Density Thruster Plumes

    Science.gov (United States)

    2010-06-04

    the nucleation process starting from the dimer formation and up using the elementary kinetic theory for cluster-cluster and cluster-monomer collisions... Astrophysical Letters and Communications, Vol. 34, 1997, pp. 245-250. 33C. Borgnakke and P.S. Larsen, “Statistical collision model for Monte Carlo simulation

  16. Detection of Plastic Explosive Traces in the Human Thermal Plume

    Science.gov (United States)

    Gowadia, Huban A.; Settles, Gary S.

    1998-11-01

    Aviation security requires the detection of explosive devices which terrorists, posing as passengers, may conceal beneath their clothing. Our goal is to understand the generation, transport, and collection of trace signals from such concealed explosives, which are found in the natural convective plume produced by the human body. Previous work (APS/DFD96, CG10) has visualized this plume and shown that concealed volatile explosives (e.g. TNT) produce a detectable vapor signal therein. Plastic explosives, on the other hand, have vanishingly low vapor pressures and are thus considered very difficult to detect. Present experiments use a dispersal chamber to collect and sample the plumes of human subjects wearing concealed gauze patches containing milligrams of RDX, the primary component of plastic explosives such as C-4. These experiments address the effects of agitation, clothing, temperature and humidity on trace detectability. Further experiments address the effects of oily vs. dry skin, contaminated clothing vs. gauze patches, and residual contamination left on skin previously in contact with RDX. The key role of airborne contaminated textile fibers is noted. Knowledge thus gained contributes to the design of an explosive detection portal for aviation security screening. (Research supported by FAA Grant 93-G-052.)

  17. Magnetic reconnection between colliding magnetized laser-produced plasma plumes.

    Science.gov (United States)

    Fiksel, G; Fox, W; Bhattacharjee, A; Barnak, D H; Chang, P-Y; Germaschewski, K; Hu, S X; Nilson, P M

    2014-09-05

    Observations of magnetic reconnection between colliding plumes of magnetized laser-produced plasma are presented. Two counterpropagating plasma flows are created by irradiating oppositely placed plastic (CH) targets with 1.8-kJ, 2-ns laser beams on the Omega EP Laser System. The interaction region between the plumes is prefilled with a low-density background plasma and magnetized by an externally applied magnetic field, imposed perpendicular to the plasma flow, and initialized with an X-type null point geometry with B=0 at the midplane and B=8  T at the targets. The counterflowing plumes sweep up and compress the background plasma and the magnetic field into a pair of magnetized ribbons, which collide, stagnate, and reconnect at the midplane, allowing the first detailed observations of a stretched current sheet in laser-driven reconnection experiments. The dynamics of current sheet formation are in good agreement with first-principles particle-in-cell simulations that model the experiments.

  18. Bioremediation of a Large Chlorinated Solvent Plume, Dover AFB, DE

    Energy Technology Data Exchange (ETDEWEB)

    Bloom, Aleisa C [ORNL

    2015-01-01

    Bioremediation of a Large Chlorinated Solvent Plume, Dover AFB, DE Aleisa Bloom, (Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA) Robert Lyon (bob.lyon@aecom.com), Laurie Stenberg, and Holly Brown (AECOM, Germantown, Maryland, USA) ABSTRACT: Past disposal practices at Dover Air Force Base (AFB), Delaware, created a large solvent plume called Area 6 (about 1 mile long, 2,000 feet wide, and 345 acres). The main contaminants are PCE, TCE, and their degradation products. The remedy is in-situ accelerated anaerobic bioremediation (AAB). AAB started in 2006 and is focusing on source areas and downgradient plume cores. Direct-push injections occurred in source areas where contamination is typically between 5 and 20 feet below ground surface. Lower concentration dissolved-phased contamination is present downgradient at 35 and 50 feet below ground surface. Here, permanent injection/extraction wells installed in transects perpendicular to the flow of groundwater are used to apply AAB. The AAB substrate is a mix of sodium lactate, emulsified vegetable oil, and nutrients. After eight years, dissolved contaminant mass within the main 80-acre treatment area has been reduced by over 98 percent. This successful application of AAB has stopped the flux of contaminants to the more distal portions of the plume. While more time is needed for effects to be seen in the distal plume, AAB injections will soon cease, and the remedy will transition to natural attenuation. INTRODUCTION Oak Ridge National Laboratory Environmental Science Division (ORNL) and AECOM (formerly URS Corporation) have successfully implemented in situ accelerated anaerobic bioremediation (AAB) to remediate chlorinated solvent contamination in a large, multi-sourced groundwater plume at Dover Air Force Base (AFB). AAB has resulted in significant reductions of dissolved phase chlorinated solvent concentrations. This plume, called Area 6, was originally over 1 mile in length and over 2,000 feet wide (Figure 1

  19. Plumes and Fountains in a Cross-Wind

    Science.gov (United States)

    Sutherland, Bruce; Anderson-Frey, Alexendra; Ansong, Joseph

    2010-11-01

    Sour gas flares attempt to burn off hydrogen sulfide (H2S), a poisonous gas that can kill at concentrations higher than 100PPM. Because in some areas of the Rocky Mountain foothills the concentration of the gas before burning can be has high as 20%, flaring must be extremely efficient to prevent disaster. Recent studies have shown that cross-winds can reduce the efficiency to 30% meaning the concentration of unburned gas at the source can be as high as 60000PPM. Engineers rely on atmospheric dispersion to reduce the concentration to tolerable levels before the plume extends to the ground. To predict the dispersion of the gas close to the source, the US Environmental Protection Agency uses a numerical model, AERMOD, that heuristically adapts plume theory to account for the effects of winds and atmospheric inversions. They do not account for the fact that H2S is heavier than air at room temperature and so would tend to pool in valleys after cooling. We have performed laboratory experiments to examine the dynamics of positively and negatively buoyant plumes in uniform and stratified environments with a uniform background flow. The results are then compared with the predictions of the AERMOD model.

  20. Martian Atmospheric Methane Plumes from Meteor Shower Infall: A Hypothesis

    Science.gov (United States)

    Fries, M.; Christou, A.; Archer, D.; Conrad, P.; Cooke, W.; Eigenbrode, J.; ten Kate, I. L.; Matney, M.; Niles, P.; Sykes, M.

    2016-01-01

    Methane plumes in the martian atmosphere have been detected using Earth-based spectroscopy, the Planetary Fourier Spectrometer on the ESA Mars Express mission, and the NASA Mars Science Laboratory. The methane's origin remains a mystery, with proposed sources including volcanism, exogenous sources like impacts and interplanetary dust, aqueous alteration of olivine in the presence of carbonaceous material, release from ancient deposits of methane clathrates, and/or biological activity. To date, none of these phenomena have been found to reliably correlate with the detection of methane plumes. An additional source exists, however: meteor showers could generate martian methane via UV pyrolysis of carbon-rich infall material. We find a correlation between the dates of Mars/cometary orbit encounters and detections of methane on Mars. We hypothesize that cometary debris falls onto Mars during these interactions, depositing freshly disaggregated meteor shower material in a regional concentration. The material generates methane via UV photolysis, resulting in a localized "plume" of short-lived methane.

  1. A Closure Model with Plumes I. The solar convection

    CERN Document Server

    Belkacem, K; Goupil, M J; Kupka, F

    2006-01-01

    Oscillations of stellar p modes, excited by turbulent convection, are investigated. We take into account the asymmetry of the up and downflows created by turbulent plumes through an adapted closure model. In a companion paper, we apply it to the formalism of excitation of solar p modes developed by Samadi & Goupil 2001. Using results from 3D numerical simulations of the upper most part of the solar convection zone, we show that the two-scale-mass-flux model (TFM) is valid only for quasi-laminar or highly skewed flows (Gryanik & Hartmann 2002). We build a generalized-Two-scale-Mass-Flux Model (GTFM) model which takes into account both the skew introduced by the presence of two flows and the effects of turbulence in each flow. In order to apply the GTFM to the solar case, we introduce the plume dynamics as modelled by Rieutord & Zahn (1995) and construct a Closure Model with Plumes (CMP). When comparing with 3D simulation results, the CMP improves the agreement for the fourth order moments, by appro...

  2. Petrological evidence for secular cooling in mantle plumes.

    Science.gov (United States)

    Herzberg, Claude; Gazel, Esteban

    2009-04-02

    Geological mapping and geochronological studies have shown much lower eruption rates for ocean island basalts (OIBs) in comparison with those of lavas from large igneous provinces (LIPs) such as oceanic plateaux and continental flood provinces. However, a quantitative petrological comparison has never been made between mantle source temperature and the extent of melting for OIB and LIP sources. Here we show that the MgO and FeO contents of Galapagos-related lavas and their primary magmas have decreased since the Cretaceous period. From petrological modelling, we infer that these changes reflect a cooling of the Galapagos mantle plume from a potential temperature of 1,560-1,620 degrees C in the Cretaceous to 1,500 degrees C at present. Iceland also exhibits secular cooling, in agreement with previous studies. Our work provides quantitative petrological evidence that, in general, mantle plumes for LIPs with Palaeocene-Permian ages were hotter and melted more extensively than plumes of more modern ocean islands. We interpret this to reflect episodic flow from lower-mantle domains that are lithologically and geochemically heterogeneous.

  3. Salem 98: A post-plume phase, federal participation exercise

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-01-01

    Salem 98 was the largest nuclear power plant post-plume phase exercise since the 1993 FRMAC-93 exercise at the Fort Calhoun Nuclear Power Plant in Nebraska. Salem 98 was a 3 Day exercise, held on May 5--7, 1998, involving participation by the States of New Jersey and Delaware and associated State and county agencies. Public Service Electric and Gas was the host utility and Salem County the host county. Federal participation included the Nuclear Regulatory Commission, Federal Emergency Management Agency, Department of Energy, Environmental Protection Agency, US department of Agriculture and Department of Health and Human Services. In addition, the American Nuclear Insurers participated, adding a dimension to the exercise not experienced often enough. This was a stand-alone post-plume phase exercise, which took place 2 months after the evaluated plume phase exercise held on March 3, 1998, also including participation by various Federal agencies. This exercise demonstrated the positive working relationship among utility, State, county, and Federal responders in response to a postulated major nuclear power plant emergency with significant offsite consequences.

  4. Anaerobic methane oxidation in a landfill-leachate plume.

    Science.gov (United States)

    Grossman, Ethan L; Cifuentes, Luis A; Cozzarelli, Isabelle M

    2002-06-01

    The alluvial aquifer adjacent to Norman Landfill, OK, provides an excellent natural laboratory for the study of anaerobic processes impacting landfill-leachate contaminated aquifers. We collected groundwaters from a transect of seven multilevel wells ranging in depth from 1.3 to 11 m that were oriented parallel to the flow path. The center of the leachate plume was characterized by (1) high alkalinity and elevated concentrations of total dissolved organic carbon, reduced iron, and methane, and (2) negligible oxygen, nitrate, and sulfate concentrations. Methane concentrations and stable carbon isotope (delta13C) values suggest anaerobic methane oxidation was occurring within the plume and at its margins. Methane delta13C values increased from about -54 per thousand near the source to > -10 per thousand downgradient and at the plume margins. The isotopic fractionation associated with this methane oxidation was -13.6+/-1.0 per thousand. Methane 13C enrichment indicated that 80-90% of the original landfill methane was oxidized over the 210-m transect. First-order rate constants ranged from 0.06 to 0.23 per year, and oxidation rates ranged from 18 to 230 microM/y. Overall, hydrochemical data suggest that a sulfate reducer-methanogen consortium may mediate this methane oxidation. These results demonstrate that natural attenuation through anaerobic methane oxidation can be an important sink for landfill methane in aquifer systems.

  5. Laser induced plasma plume imaging and surface morphology of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Khaleeq-ur-Rahman, M. [Advanced Physics Laboratory, Department of Physics, University of Engineering and Technology, G.T. Road, Lahore 54890 (Pakistan); Siraj, K. [Advanced Physics Laboratory, Department of Physics, University of Engineering and Technology, G.T. Road, Lahore 54890 (Pakistan)], E-mail: ksiraj@uet.edu.pk; Rafique, M.S.; Bhatti, K.A.; Latif, A.; Jamil, H.; Basit, M. [Advanced Physics Laboratory, Department of Physics, University of Engineering and Technology, G.T. Road, Lahore 54890 (Pakistan)

    2009-04-15

    Shot-to-shot variation in the characteristics of laser produced plasma plume and surface profile of N-type silicon (1 1 1) are investigated. In order to produce plasma, a Q-switched Nd: YAG laser (1064 nm, 10 mJ, 9-14 ns) is tightly focused on silicon target in air at room temperature. Target was exposed in such a way that number of laser shots was increased from point to point in ascending order starting from single shot at first point. Target was moved 2 mm after each exposure. In order to investigate shot-to-shot variation in the time integrated emission intensity regions within the plasma plume, a computer controlled CCD based image capture system was employed. Various intensity regimes were found depending strongly on the number of incident laser pulses. Plasma plume length was also found to vary with the number of pulses. The topographic analysis of the irradiated Si was performed by Scanning Electron Microscope (SEM) which shows the primary mechanisms like thermal or non-thermal ablation depend on the number of shots. Surface morphological changes were also studied in terms of ripple formation, ejection, debris and re-deposition of material caused by laser beam at sample surface. The micrographs show ripples spacing versus wavelength dependence rule [{lambda} {approx} {lambda}/(1 - sin {theta})]. Intensity variations with number of shots are correlated with the surface morphology of the irradiated sample.

  6. Thermography of the New River Inlet plume and nearshore currents

    Science.gov (United States)

    Chickadel, C.; Jessup, A.

    2012-12-01

    As part of the DARLA and RIVET experiments, thermal imaging systems mounted on a tower and in an airplane captured water flow in the New River Inlet, NC, USA. Kilometer-scale, airborne thermal imagery of the inlet details the ebb flow of the estuarine plume water mixing with ocean water. Multiple fronts, corresponding to the preferred channels through the ebb tidal delta, are imaged in the aerial data. A series of internal fronts suggest discreet sources of the tidal plume that vary with time. Focused thermal measurements made from a tower on the south side of the inlet viewed an area within a radius of a few hundred meters. Sub-meter resolution video from the tower revealed fine-scale flow features and the interaction of tidal exchange and wave-forced surfzone currents. Using the tower and airborne thermal image data we plan to provide geophysical information to compare with numerical models and in situ measurements made by other investigators. From the overflights, we will map the spatial and temporal extent of the estuarine plume to correlate with tidal phase and local wind conditions. From the tower data, we will investigate the structure of the nearshore flow using a thermal particle image velocimetry (PIV) technique, which is based on tracking motion of the surface temperature patterns. Long term variability of the mean and turbulent two-dimensional PIV currents will be correlated to local wave, tidal, and wind forcing parameters.

  7. Design of bioaugmented biobarriers for remediation of a TCE plume

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, C.; Grant, G.; Konzuk, J.; Bogaart, M.; Duffy, M.; Grinyer, W.; Major, D. [Geosyntec Consultants, Atlanta, GA (United States); Le, S.; Tamashiro, P-F. [NAVFAC Southwest, Ventura County, CA (United States)

    2008-07-01

    The design of bioaugmented biobarriers for remediation of a trichloroethene (TCE) plume was discussed in this presentation. Specifically, the presentation provided a description of the site and presented the general bioremediation approach. It also discussed microcosm testing, emulsified oil (EVO) pilot testing, modeling, and final design. The biodegradation of TCE was discussed. It was described as having the following steps: sequential reductive dechlorination carried out by dechlorinating bacteria; chlorine replaced by hydrogen atom; hydrogen produced during fermentation of EVO; and dehalococcoides (DHC) bacteria capable of degrading cDCE to ethene. The presentation discussed the bioaugmentation with KB-1 culture, EVO as a long-term electron donor, passive bioremediation approach, and full-scale design objectives. These included the remediation of TCE and daughter products within the plume and source within 50 years; minimizing costs; and determining the number, dimensions, and optimum placement of biobarriers. The microcosm study proved to be useful for determining biodegradation half-lives for bioaugmentation/EVO treatments and that TCE rapidly and completely converted to ethene with KB-1 and EVO addition. In addition, the natural attenuation within the plume was slow. tabs., figs.

  8. Volcanic Plume Above Mount St. Helens Detected with GPS

    Science.gov (United States)

    Houlié, N.; Briole, P.; Nercessian, A.; Murakami, M.

    2005-07-01

    Eruptions can produce not only flows of incandescent material along the slopes of a volcano but also ash plumes in the troposphere [Sparks et al., 1997] that can threaten aircraft flying in the vicinity [Fisher et al., 1997]. To protect aircraft, passengers, and crews, the International Civil Aviation Organization and the World Meteorological Organization created eight Volcanic Ash Advisory Centers (VAAC, http://www.ssd.noaa.gov/VAAC/vaac.html) around the globe with the goal of tracking volcanic plumes and releasing eruption alerts to airports, pilots, and companies. Currently, the VAAC monitoring system is based mostly on the monitoring systems of any local volcano observatories and on real-time monitoring of data acquired by meteorological satellites. In the case of the 18 August 2000 eruption of the Miyakejima volcano in Japan, Houlié et al. [2005] showed that the Global Positioning System(GPS) might be used as an additional tool for monitoring volcanic plumes. The present article indicates that the 9 March 2005 eruption of Mount St. Helens, Washington, also produced detectable anomalies in GPS data.>

  9. Lidar measurements of solid rocket propellant fire particle plumes.

    Science.gov (United States)

    Brown, David M; Brown, Andrea M; Willitsford, Adam H; Dinello-Fass, Ryan; Airola, Marc B; Siegrist, Karen M; Thomas, Michael E; Chang, Yale

    2016-06-10

    This paper presents the first, to our knowledge, direct measurement of aerosol produced by an aluminized solid rocket propellant (SRP) fire on the ground. Such fires produce aluminum oxide particles small enough to loft high into the atmosphere and disperse over a wide area. These results can be applied to spacecraft launchpad accidents that expose spacecraft to such fires; during these fires, there is concern that some of the plutonium from the spacecraft power system will be carried with the aerosols. Accident-related lofting of this material would be the net result of many contributing processes that are currently being evaluated. To resolve the complexity of fire processes, a self-consistent model of the ground-level and upper-level parts of the plume was determined by merging ground-level optical measurements of the fire with lidar measurements of the aerosol plume at height during a series of SRP fire tests that simulated propellant fire accident scenarios. On the basis of the measurements and model results, the Johns Hopkins University Applied Physics Laboratory (JHU/APL) team was able to estimate the amount of aluminum oxide (alumina) lofted into the atmosphere above the fire. The quantification of this ratio is critical for a complete understanding of accident scenarios, because contaminants are transported through the plume. This paper provides an estimate for the mass of alumina lofted into the air.

  10. Heavy hitters via cluster-preserving clustering

    DEFF Research Database (Denmark)

    Larsen, Kasper Green; Nelson, Jelani; Nguyen, Huy L.

    2016-01-01

    , providing correctness whp. In fact, a simpler version of our algorithm for p = 1 in the strict turnstile model answers queries even faster than the "dyadic trick" by roughly a log n factor, dominating it in all regards. Our main innovation is an efficient reduction from the heavy hitters to a clustering...... problem in which each heavy hitter is encoded as some form of noisy spectral cluster in a much bigger graph, and the goal is to identify every cluster. Since every heavy hitter must be found, correctness requires that every cluster be found. We thus need a "cluster-preserving clustering" algorithm......, that partitions the graph into clusters with the promise of not destroying any original cluster. To do this we first apply standard spectral graph partitioning, and then we use some novel combinatorial techniques to modify the cuts obtained so as to make sure that the original clusters are sufficiently preserved...

  11. Plume-tectonics for exploring the past and future of the earth. Marugoto chikyukan 'plume tectonics' towa

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, S. (Tokyo Institute of Technology, Tokyo (Japan). Faculty of Science)

    1994-06-15

    This paper briefly explains the behavior of the inside of the Earth that has been becoming clearer as the seismic wave tomography and other instruments have been improved. It also describes the plume-tectonics. A plume represents a mass of mantle in the mantle layer that is hotter or colder than the sounding part of the layer. The seismic wave tomography provides a view of two large hot areas on the Earth, one below the South Pacific Ocean and the other below Southern Africa, and a cold area below Asia. There are huge rising and falling flows (plumes) in the mantle, forming a convection. Plumes are very huge; the diameter of a plume may be about 5,000 km, rising high from the bottom of the mantle to the plate level, and extending as long as about 2,900 km. When a cold plume falls on the core and causes a slight difference in temperature between the core and the plume in any part of the interface, a hot plume is produced in the part where temperature is not even. The mechanism of the continents joining or separating from each other in the periods of hundreds of millions of years. The first key to a new theory is cooling of the Earth. 3 figs.

  12. Stormwater plume detection by MODIS imagery in the southern California coastal ocean

    Science.gov (United States)

    Nezlin, N.P.; DiGiacomo, P.M.; Diehl, D.W.; Jones, B.H.; Johnson, S.C.; Mengel, M.J.; Reifel, K.M.; Warrick, J.A.; Wang, M.

    2008-01-01

    Stormwater plumes in the southern California coastal ocean were detected by MODIS-Aqua satellite imagery and compared to ship-based data on surface salinity and fecal indicator bacterial (FIB) counts collected during the Bight'03 Regional Water Quality Program surveys in February-March of 2004 and 2005. MODIS imagery was processed using a combined near-infrared/shortwave-infrared (NIR-SWIR) atmospheric correction method, which substantially improved normalized water-leaving radiation (nLw) optical spectra in coastal waters with high turbidity. Plumes were detected using a minimum-distance supervised classification method based on nLw spectra averaged within the training areas, defined as circular zones of 1.5-5.0-km radii around field stations with a surface salinity of S 33.0 ('ocean'). The plume optical signatures (i.e., the nLw differences between 'plume' and 'ocean') were most evident during the first 2 days after the rainstorms. To assess the accuracy of plume detection, stations were classified into 'plume' and 'ocean' using two criteria: (1) 'plume' included the stations with salinity below a certain threshold estimated from the maximum accuracy of plume detection; and (2) FIB counts in 'plume' exceeded the California State Water Board standards. The salinity threshold between 'plume' and 'ocean' was estimated as 32.2. The total accuracy of plume detection in terms of surface salinity was not high (68% on average), seemingly because of imperfect correlation between plume salinity and ocean color. The accuracy of plume detection in terms of FIB exceedances was even lower (64% on average), resulting from low correlation between ocean color and bacterial contamination. Nevertheless, satellite imagery was shown to be a useful tool for the estimation of the extent of potentially polluted plumes, which was hardly achievable by direct sampling methods (in particular, because the grids of ship-based stations covered only small parts of the plumes detected via

  13. The Green Propellant Infusion Mission Thruster Performance Testing for Plume Diagnostics

    Science.gov (United States)

    Deans, Matthew C.; Reed, Brian D.; Arrington, Lynn A.; Williams, George J.; Kojima, Jun J.; Kinzbach, McKenzie I.; McLean, Christopher H.

    2014-01-01

    The Green Propellant Infusion Mission (GPIM) is sponsored by NASA's Space Technology Mission Directorate (STMD) Technology Demonstration Mission (TDM) office. The goal of GPIM is to advance the technology readiness level of a green propulsion system, specifically, one using the monopropellant, AF-M315E, by demonstrating ground handling, spacecraft processing, and on-orbit operations. One of the risks identified for GPIM is potential contamination of sensitive spacecraft surfaces from the effluents in the plumes of AF-M315E thrusters. NASA Glenn Research Center (GRC) is conducting activities to characterize the effects of AF-M315E plume impingement and deposition. GRC has established individual plume models of the 22-N and 1-N thrusters that will be used on the GPIM spacecraft. The model simulations will be correlated with plume measurement data from Laboratory and Engineering Model 22-N, AF-M315E thrusters. The thrusters are currently being tested in a small rocket, altitude facility at NASA GRC. A suite of diagnostics, including Raman spectroscopy, Rayleigh spectroscopy, and Schlieren imaging are being used to acquire plume measurements of AF-M315E thrusters. Plume data will include temperature, velocity, relative density, and species concentration. The plume measurement data will be compared to the corresponding simulations of the plume model. The GRC effort will establish a data set of AF-M315E plume measurements and a plume model that can be used for future AF-M315E applications.

  14. Plume Characterization of a Laboratory Model 22 N GPIM Thruster via High-Frequency Raman Spectroscopy

    Science.gov (United States)

    Williams, George J.; Kojima, Jun J.; Arrington, Lynn A.; Deans, Matthew C.; Reed, Brian D.; Kinzbach, McKenzie I.; McLean, Christopher H.

    2015-01-01

    The Green Propellant Infusion Mission (GPIM) will demonstrate the capability of a green propulsion system, specifically, one using the monopropellant, AF-M315E. One of the risks identified for GPIM is potential contamination of sensitive areas of the spacecraft from the effluents in the plumes of AF-M315E thrusters. Plume characterization of a laboratory-model 22 N thruster via optical diagnostics was conducted at NASA GRC in a space-simulated environment. A high-frequency pulsed laser was coupled with an electron-multiplied ICCD camera to perform Raman spectroscopy in the near-field, low-pressure plume. The Raman data yielded plume constituents and temperatures over a range of thruster chamber pressures and as a function of thruster (catalyst) operating time. Schlieren images of the near-field plume enabled calculation of plume velocities and revealed general plume structure of the otherwise invisible plume. The measured velocities are compared to those predicted by a two-dimensional, kinetic model. Trends in data and numerical results are presented from catalyst mid-life to end-of-life. The results of this investigation were coupled with the Raman and Schlieren data to provide an anchor for plume impingement analysis presented in a companion paper. The results of both analyses will be used to improve understanding of the nature of AF-M315E plumes and their impacts to GPIM and other future missions.

  15. Mapping ocean outfall plumes and their mixing using autonomous underwater vehicles

    Science.gov (United States)

    Rogowski, Peter; Terrill, Eric; Otero, Mark; Hazard, Lisa; Middleton, William

    2012-07-01

    This paper reports on developing autonomous underwater vehicle (AUV) survey methods for ocean outfall discharge plumes and new insights gained on plume mixing. Unique to the study is mapping the discharge mixing using colored dissolved organic matter (CDOM) calibrated for effluent dilution. AUV mission planning methodologies for discharge plume sampling, plume characterization using onboard temperature, salinity and optical sensors, and comparison of observational data to model results are presented for the Point Loma Ocean Outfall offshore of San Diego, CA. The results are expected to be applicable to the general theme of mixing of submerged buoyant discharges. In the near-field, the plume is found to mix to a height consistent with the predictions of buoyant jet engineering models. At the far-field, the fine spatial scales of the plume resolved by the vehicle suggests that shear instabilities caused by internal waves can enhance plume mixing and elevate the discharge plume above the predicted equilibrium rise height. These results suggest that even under variable oceanic conditions, properly planned missions for AUVs equipped with an optical CDOM sensor in addition to traditional physical oceanographic sensors, can accurately map the mixing of ocean outfall plumes at resolutions not possible with traditional boat-based techniques. Variations of oceanic conditions are found to influence the mixing and fate of the plume at time scales generally not considered in the design of these discharges.

  16. Modeling Smoke Plume-Rise and Dispersion from Southern United States Prescribed Burns with Daysmoke

    Directory of Open Access Journals (Sweden)

    Mehmet Talat Odman

    2011-08-01

    Full Text Available We present Daysmoke, an empirical-statistical plume rise and dispersion model for simulating smoke from prescribed burns. Prescribed fires are characterized by complex plume structure including multiple-core updrafts which makes modeling with simple plume models difficult. Daysmoke accounts for plume structure in a three-dimensional veering/sheering atmospheric environment, multiple-core updrafts, and detrainment of particulate matter. The number of empirical coefficients appearing in the model theory is reduced through a sensitivity analysis with the Fourier Amplitude Sensitivity Test (FAST. Daysmoke simulations for “bent-over” plumes compare closely with Briggs theory although the two-thirds law is not explicit in Daysmoke. However, the solutions for the “highly-tilted” plume characterized by weak buoyancy, low initial vertical velocity, and large initial plume diameter depart considerably from Briggs theory. Results from a study of weak plumes from prescribed burns at Fort Benning GA showed simulated ground-level PM2.5 comparing favorably with observations taken within the first eight kilometers of eleven prescribed burns. Daysmoke placed plume tops near the lower end of the range of observed plume tops for six prescribed burns. Daysmoke provides the levels and amounts of smoke injected into regional scale air quality models. Results from CMAQ with and without an adaptive grid are presented.

  17. Spacecraft plume interactions with the magnetosphere plasma environment in geostationary Earth orbit

    Science.gov (United States)

    Stephani, K. A.; Boyd, I. D.

    2016-02-01

    Particle-based kinetic simulations of steady and unsteady hydrazine chemical rocket plumes are presented in a study of plume interactions with the ambient magnetosphere in geostationary Earth orbit. The hydrazine chemical rocket plume expands into a near-vacuum plasma environment, requiring the use of a combined direct simulation Monte Carlo/particle-in-cell methodology for the rarefied plasma conditions. Detailed total and differential cross sections are employed to characterize the charge exchange reactions between the neutral hydrazine plume mixture and the ambient hydrogen ions, and ion production is also modeled for photoionization processes. These ionization processes lead to an increase in local plasma density surrounding the spacecraft owing to a partial ionization of the relatively high-density hydrazine plume. Results from the steady plume simulations indicate that the formation of the hydrazine ion plume are driven by several competing mechanisms, including (1) local depletion and (2) replenishing of ambient H+ ions by charge exchange and thermal motion of 1 keV H+ from the ambient reservoir, respectively, and (3) photoionization processes. The self-consistent electrostatic field forces and the geostationary magnetic field have only a small influence on the dynamics of the ion plume. The unsteady plume simulations show a variation in neutral and ion plume dissipation times consistent with the variation in relative diffusion rates of the chemical species, with full H2 dissipation (below the ambient number density levels) approximately 33 s after a 2 s thruster burn.

  18. Three-dimensional laboratory modeling of the Tonga trench and Samoan plume interaction

    Science.gov (United States)

    Druken, K. A.; Kincaid, C. R.; Pockalny, R. A.; Griffiths, R. W.; Hart, S. R.

    2009-12-01

    Plume processes occurring near ridge centers (e.g. Iceland) or mid-plate (e.g. Hawaii) have been well studied; however, the behavior of a plume near a subducting plate is still poorly understood and may in fact differ from the typical expected plume surfacing patterns. We investigate how three-dimensional subduction-driven flow relates to the deformation and dispersal of nearby upwelling plume material and the associated geochemical spatial patterns, with site-specific comparisons to the Tonga trench and Samoan plume system. Eighteen plume-trench laboratory experiments were conducted with varied combinations of subduction motions (down-dip, trench rollback, slab steepening and back-arc extension) and plume parameters (position and temperature.) A phenolic plate and glucose syrup, with a temperature dependent viscosity, are used to model the slab and upper mantle, respectively. Hydraulic pistons control longitudinal, translational and steepening motions of the slab as a simplified kinematic approach to mimic dynamic experiments. Results show that the subduction-induced flow dominates the upwelling strength of the plume, causing a significant portion of the plume head to subduct before reaching the melt zone. The remaining material is entrained around the slab edge into the mantle wedge by the trench rollback-induced flow. The proportion of subducted verses entrained material is predominantly dependent on plume location (relative to the trench) and thermal strength, with additional effects from back-arc extension and plate steepening.

  19. Ozone production efficiency of a ship-plume: ITCT 2K2 case study.

    Science.gov (United States)

    Kim, Hyun S; Kim, Yong H; Han, Kyung M; Kim, Jhoon; Song, Chul H

    2016-01-01

    Ozone production efficiency (OPE) of ship plume was first evaluated in this study, based on ship-plume photochemical/dynamic model simulations and the ship-plume composition data measured during the ITCT 2K2 (Intercontinental Transport and Chemical Transformation 2002) aircraft campaign. The averaged instantaneous OPEs (OPE(i)‾) estimated via the ship-plume photochemical/dynamic modeling for the ITCT 2K2 ship-plume ranged between 4.61 and 18.92, showing that the values vary with the extent of chemical evolution (or chemical stage) of the ship plume and the stability classes of the marine boundary layer (MBL). Together with OPE(i)‾, the equivalent OPEs (OPE(e)‾) for the entire ITCT 2K2 ship-plume were also estimated. The OPE(e)‾ values varied between 9.73 (for the stable MBL) and 12.73 (for the moderately stable MBL), which agreed well with the OPE(e)‾ of 12.85 estimated based on the ITCT 2K2 ship-plume observations. It was also found that both the model-simulated and observation-based OPE(e)‾ inside the ship-plume were 0.29-0.38 times smaller than the OPE(e)‾ calculated/measured outside the ITCT 2K2 ship-plume. Such low OPEs insides the ship plume were due to the high levels of NO and non-liner ship-plume photochemistry. Possible implications of this ship-plume OPE study in the global chemistry-transport modeling are also discussed.

  20. The effect of recycled oceanic crust in the thermal evolution of the Galapagos Plume

    Science.gov (United States)

    Gazel, E.; Herzberg, C. T.; Vidito, C. A.

    2011-12-01

    Current models suggest that the massive basaltic production responsible for the emplacement of Large Igneous Provinces (LIPS) during the Permian-Paleocene may represent the initial phases (plume heads) of some of the mantle plumes that feed the current ocean island basalts (OIB). In many cases, magmatism associated with the initiation of mantle plumes was so voluminous that produced global environmental impacts. The origin of these intra-plate magmatism is still debated but recent petrological, geochemical and geophysical studies of some of these localities like Samoa, Hawaii, Galapagos, provide evidence that melting is related to a true mantle plume, representing a geochemically heterogeneous, hot-buoyant domain that originates from a boundary layer beneath the upper mantle. Thus, plume-related magmas produced in OIB and LIPS and their connecting plume tracks are windows into the Earth's mantle, providing evidence on mantle temperature, size and composition of heterogeneities, and the deep earth geochemical cycles. Our preliminary petrological modeling suggests that mantle plumes for LIPS with Permian-Paleocene ages were generally hotter and melted more extensively than plumes of more modern oceanic islands. Although a lot of work has been done on LIPS and OIB, no complete record of the evolution of a mantle plume is available to this point, mostly due to the inaccessibility of the submerged sections of almost all plume tracks. Galapagos-related lavas provide a complete record of the evolution of a mantle plume since the plume's initial stages in the Cretaceous. In the case of the Galapagos, our work suggests a decrease from TP(max) of1650 C in the Cretaceous to 1500 C in the present day. Our recent work on the Galapagos Islands and the preliminary work on older Galapagos-related terranes suggest that this secular cooling is directly related with increasing amounts of recycled crust in the plume.

  1. 3-D thermo-mechanical modeling of plume-induced subduction initiation

    Science.gov (United States)

    Baes, M.; Gerya, T.; Sobolev, S. V.

    2016-11-01

    Here, we study the 3-D subduction initiation process induced by the interaction between a hot thermo-chemical mantle plume and oceanic lithosphere using thermo-mechanical viscoplastic finite difference marker-in-cell models. Our numerical modeling results show that self-sustaining subduction is induced by plume-lithosphere interaction when the plume is sufficiently buoyant, the oceanic lithosphere is sufficiently old and the plate is weak enough to allow the buoyant plume to pass through it. Subduction initiation occurs following penetration of the lithosphere by the hot plume and the downward displacement of broken, nearly circular segments of lithosphere (proto-slabs) as a result of partially molten plume rocks overriding the proto-slabs. Our experiments show four different deformation regimes in response to plume-lithosphere interaction: a) self-sustaining subduction initiation, in which subduction becomes self-sustaining; b) frozen subduction initiation, in which subduction stops at shallow depths; c) slab break-off, in which the subducting circular slab breaks off soon after formation; and d) plume underplating, in which the plume does not pass through the lithosphere and instead spreads beneath it (i.e., failed subduction initiation). These regimes depend on several parameters, such as the size, composition, and temperature of the plume, the brittle/plastic strength and age of the oceanic lithosphere, and the presence/absence of lithospheric heterogeneities. The results show that subduction initiates and becomes self-sustaining when the lithosphere is older than 10 Myr and the non-dimensional ratio of the plume buoyancy force and lithospheric strength above the plume is higher than approximately 2. The outcomes of our numerical experiments are applicable for subduction initiation in the modern and Precambrian Earth and for the origin of plume-related corona structures on Venus.

  2. Multifrequency radar imaging of ash plumes: an experiment at Stromboli

    Science.gov (United States)

    Donnadieu, Franck; Freret-Lorgeril, Valentin; Delanoë, Julien; Vinson, Jean-Paul; Peyrin, Frédéric; Hervier, Claude; Caudoux, Christophe; Van Baelen, Joël; Latchimy, Thierry

    2016-04-01

    Volcanic ash emissions in the atmosphere are hazardous to aviation while ash fallout affects people and human activities and may cause damage to infrastructures and economic losses. In the framework of the French Government Laboratory of Excellence ClerVolc initiative, an experiment was carried out on Stromboli volcano (Italy), between 28 September and 4 October 2015. The aim was to retrieve various physical properties of the ash plumes, especially the mass loading parameters which are critical for the modelling of ash dispersal. We used a complementary set of cutting edge techniques recording in different bands of the electromagnetic spectrum. The innovative instrument setup consisted in three radars, hyperspectral thermal infrared and dual-band UV cameras, a mini DOAS-Flyspec and a multigas sensor. A drone equipped with differential GPS was flown near the ash plumes with several sensors including SO2, CO2 and particle counter. We mainly focus on radar measurements of over 200 ash plumes and present some preliminary comparisons at three frequencies. The BASTA Doppler radar at 95 GHz, originally designed for atmospheric studies, was deployed at about 2.2 km in slant distance from the eruptive craters. It was configured to observe volumes above one of the active craters with a spatio-temporal resolution of 12.5 m and 1 s. From the same location, a 1.2 GHz volcano Doppler radar (VOLDORAD) was recording the signature of ballistics and small lapilli at 0.15 s in 60 m-deep volumes. In addition, a commercial 24 GHz micro rain Doppler radar (MRR) simultaneously recorded activity from the Rochette station, at 400 to 650 m from the active craters with a sampling rate of 10 s and a resolution of 25 m. The latter was pointing almost perpendicularly to the other radar beams. Reflectivity factors were measured inside the ash plume above the source vent by the BASTA radar (3 mm wavelength) spanning -9 to +21 dBZ. Fallout could sometimes be tracked during several minutes within

  3. Do plumes exist beneath Northwest Kyushu southwest Japan?

    Science.gov (United States)

    Mashima, H.

    2014-12-01

    A thermal plume model was proposed for the Hot-spot type volcanism at Northwest Kyushu, southwest Japan in the post period of opening of the Sea of Japan. The model regards the Northwest Kyushu Basalts (NWKBs) were magmas fractionated from parental magmas with MgO = 12.8 - 18.8 wt. %, indicating that partial melting occurred at temperatures from 1330 to 1500 °C and at pressures from 1.5 to 3.0 GPa (Sakuyama et al., 2009; 2014). Previous petrological and observations, however, indicate that the NWKBs separated from the source mantle at pressures shallower than those inferred from the plume model. The Mg-Fe-Ni compositions of some NWKBs suggest that they could have been in equilibrium with mantle olivines with Fo = 81 - 87, meaning that they would have been not fractionated but primitive magmas. The NWKBs are associated with primitive high magnesium andesites, indicating that partial melting continued at low pressure such as 0.5 GPa (Mashima, 2009a, b). NWKBs include not garnet lherzolite xenoliths but spinel lherzolite, showing that primitive melt separation occurred at pressure lower than 2GPa (Arai et al., 2001). These lines of evidence indicate that the separation of primitive NWKBs occurred at temperature up to 1250 °C and pressures from 0.5 to 1.5 GPa, significantly lower than those assumed by the plume model. Instead of the plume model, geology of NW Kyushu infers that the volcanism was a consequence of the tectonic evolution of NW Kyushu. The volcanism was leaks of asthenosphere thickened extensional tectonics from the Paleogene to the early Miocene. Orientations of NWKB dikes indicate their eruption was induced by the reactivation of preexisting faults under horizontal compressive stress field oriented to a NW-SE direction. This horizontally compressive stress field would have been caused by mechanical interactions between the subducting Philippine Sea pate and the Eurasian Plate. The NW Kyushu volcanism could be explained in the context of plate

  4. Analysis of Nozzle Jet Plume Effects on Sonic Boom Signature

    Science.gov (United States)

    Bui, Trong

    2010-01-01

    An axisymmetric full Navier-Stokes computational fluid dynamics (CFD) study was conducted to examine nozzle exhaust jet plume effects on the sonic boom signature of a supersonic aircraft. A simplified axisymmetric nozzle geometry, representative of the nozzle on the NASA Dryden NF-15B Lift and Nozzle Change Effects on Tail Shock (LaNCETS) research airplane, was considered. The highly underexpanded nozzle flow is found to provide significantly more reduction in the tail shock strength in the sonic boom N-wave pressure signature than perfectly expanded and overexpanded nozzle flows. A tail shock train in the sonic boom signature, similar to what was observed in the LaNCETS flight data, is observed for the highly underexpanded nozzle flow. The CFD results provide a detailed description of the nozzle flow physics involved in the LaNCETS nozzle at different nozzle expansion conditions and help in interpreting LaNCETS flight data as well as in the eventual CFD analysis of a full LaNCETS aircraft. The current study also provided important information on proper modeling of the LaNCETS aircraft nozzle. The primary objective of the current CFD research effort was to support the LaNCETS flight research data analysis effort by studying the detailed nozzle exhaust jet plume s imperfect expansion effects on the sonic boom signature of a supersonic aircraft. Figure 1 illustrates the primary flow physics present in the interaction between the exhaust jet plume shock and the sonic boom coming off of an axisymmetric body in supersonic flight. The steeper tail shock from highly expanded jet plume reduces the dip of the sonic boom N-wave signature. A structured finite-volume compressible full Navier-Stokes CFD code was used in the current study. This approach is not limited by the simplifying assumptions inherent in previous sonic boom analysis efforts. Also, this study was the first known jet plume sonic boom CFD study in which the full viscous nozzle flow field was modeled, without

  5. Cluster headache

    Directory of Open Access Journals (Sweden)

    Ducros Anne

    2008-07-01

    Full Text Available Abstract Cluster headache (CH is a primary headache disease characterized by recurrent short-lasting attacks (15 to 180 minutes of excruciating unilateral periorbital pain accompanied by ipsilateral autonomic signs (lacrimation, nasal congestion, ptosis, miosis, lid edema, redness of the eye. It affects young adults, predominantly males. Prevalence is estimated at 0.5–1.0/1,000. CH has a circannual and circadian periodicity, attacks being clustered (hence the name in bouts that can occur during specific months of the year. Alcohol is the only dietary trigger of CH, strong odors (mainly solvents and cigarette smoke and napping may also trigger CH attacks. During bouts, attacks may happen at precise hours, especially during the night. During the attacks, patients tend to be restless. CH may be episodic or chronic, depending on the presence of remission periods. CH is associated with trigeminovascular activation and neuroendocrine and vegetative disturbances, however, the precise cautive mechanisms remain unknown. Involvement of the hypothalamus (a structure regulating endocrine function and sleep-wake rhythms has been confirmed, explaining, at least in part, the cyclic aspects of CH. The disease is familial in about 10% of cases. Genetic factors play a role in CH susceptibility, and a causative role has been suggested for the hypocretin receptor gene. Diagnosis is clinical. Differential diagnoses include other primary headache diseases such as migraine, paroxysmal hemicrania and SUNCT syndrome. At present, there is no curative treatment. There are efficient treatments to shorten the painful attacks (acute treatments and to reduce the number of daily attacks (prophylactic treatments. Acute treatment is based on subcutaneous administration of sumatriptan and high-flow oxygen. Verapamil, lithium, methysergide, prednisone, greater occipital nerve blocks and topiramate may be used for prophylaxis. In refractory cases, deep-brain stimulation of the

  6. Partitional clustering algorithms

    CERN Document Server

    2015-01-01

    This book summarizes the state-of-the-art in partitional clustering. Clustering, the unsupervised classification of patterns into groups, is one of the most important tasks in exploratory data analysis. Primary goals of clustering include gaining insight into, classifying, and compressing data. Clustering has a long and rich history that spans a variety of scientific disciplines including anthropology, biology, medicine, psychology, statistics, mathematics, engineering, and computer science. As a result, numerous clustering algorithms have been proposed since the early 1950s. Among these algorithms, partitional (nonhierarchical) ones have found many applications, especially in engineering and computer science. This book provides coverage of consensus clustering, constrained clustering, large scale and/or high dimensional clustering, cluster validity, cluster visualization, and applications of clustering. Examines clustering as it applies to large and/or high-dimensional data sets commonly encountered in reali...

  7. Clustering and Community Detection with Imbalanced Clusters

    OpenAIRE

    Aksoylar, Cem; Qian, Jing; Saligrama, Venkatesh

    2016-01-01

    Spectral clustering methods which are frequently used in clustering and community detection applications are sensitive to the specific graph constructions particularly when imbalanced clusters are present. We show that ratio cut (RCut) or normalized cut (NCut) objectives are not tailored to imbalanced cluster sizes since they tend to emphasize cut sizes over cut values. We propose a graph partitioning problem that seeks minimum cut partitions under minimum size constraints on partitions to de...

  8. Laboratory-Scale Simulation of Spiral Plumes in Fluid with Hight Ptandtl Number

    CERN Document Server

    Sharifulin, A N

    2013-01-01

    We experimentally investigated the appearance of a plumes from local hot spot and study its interaction with cellular flow in closed cavity filled by silicon oil with Prandtl number Pr ~2*10^3 . Convective plume is generated by a local heat source, located on the top of the small rubber cylinder, which is located in the center of the bottom of the rectangular cell. Green laser has been used to simulate the hot-spot. Roll-type large-scale convective flow is generated by heating of the one vertical sides of cavity. Influence of power of hot point on the shape of plume has been investigated. It is shown that the presence of cellular convective motion may lead to the formation of a strange spiral convective plume. This plume looks like Archimedes spiral replaced on vertical plane. Physical mechanism of the formation of strange spiral plume and application of obtained results for mantle convection problems are discussed.

  9. Plasma Plume Characterization of the HERMeS during a 1722-hr Wear Test Campaign

    Science.gov (United States)

    Huang, Wensheng; Williams, George J.; Peterson, Peter Y.; Kamhawi, Hani; Gilland, James H.; Herman, Daniel A.

    2017-01-01

    A 1722-hour wear test campaign of NASAs 12.5 kilowatt Hall Effect Rocket with Magnetic Shielding was completed. This wear test campaign, completed in 2016, was divided into four segments including an electrical configuration characterization test, two short duration tests, and one long wear test. During the electrical configuration characterization test, the plasma plume was examined to provide data to support the down select of the electrical configuration for further testing. During the long wear tests, the plasma plume was periodically examined for indications of changes in thruster behavior. Examination of the plasma plume data from the electrical configuration characterization test revealed a correlation between the plume properties and the presence of a conduction path through the front poles. Examination of the long wear test plasma plume data revealed that the plume characteristics remained unchanged during testing to within the measurement uncertainty.

  10. Ash plume properties retrieved from infrared images: a forward and inverse modeling approach

    CERN Document Server

    Cerminara, Matteo; Valade, Sébastien; Harris, Andrew J L

    2014-01-01

    We present a coupled fluid-dynamic and electromagnetic model for volcanic ash plumes. In a forward approach, the model is able to simulate the plume dynamics from prescribed input flow conditions and generate the corresponding synthetic thermal infrared (TIR) image, allowing a comparison with field-based observations. An inversion procedure is then developed to retrieve ash plume properties from TIR images. The adopted fluid-dynamic model is based on a one-dimensional, stationary description of a self-similar (top-hat) turbulent plume, for which an asymptotic analytical solution is obtained. The electromagnetic emission/absorption model is based on the Schwarzschild's equation and on Mie's theory for disperse particles, assuming that particles are coarser than the radiation wavelength and neglecting scattering. [...] Application of the inversion procedure to an ash plume at Santiaguito volcano (Guatemala) has allowed us to retrieve the main plume input parameters, namely the initial radius $b_0$, velocity $U_...

  11. The Upgraded European Digital Upper Atmosphere Server: new DIAS products for the high latitude ionosphere, the topside ionosphere and the plasmasphere

    Science.gov (United States)

    Belehaki, Anna; Kutiev, Ivan; Zolesi, Bruno; Tsagouri, Ioanna; Dialetis, Dimitris; Marinov, Pencho; Fidanova, Stefka; Cander, Lili; Pietrella, Marco; Tziotziou, Kostas; Lykiardopoulos, Angelos

    2013-04-01

    Knowledge of the state of the upper atmosphere, and in particular its ionized part, is very important in several applications affected by space weather, especially the communications and navigation systems that rely on radio transmission. To better classify the ionosphere and forecast its disturbances over Europe, a data and model infrastructure platform called the European Digital Upper Atmosphere Server (DIAS) has been established in the National Observatory of Athens by a European consortium formed around eight ionospheric stations, and funded by the European Commission. The DIAS system operates since 2006 and the basic products that are delivered are real-time and historical ionograms, frequency plots and maps of the ionosphere on the foF2, M(3000)F2, MUF and bottomside electron density, as well as long term and short term forecasting up to 24 hour ahead. The DIAS system supports more than 500 subscribed users, including telecommunication companies, satellite operators, space agencies, radio amateurs, research organizations and the space weather scientific community. In 2012 the system has been upgraded, in close collaboration between the National Observatory of Athens, the Istituto Nazionale di Geofisica e Vulcanologia and the Bulgarian Academy of Sciences, with funding from the ESA/SSA Programme. The first group of new products results from the implementation of the TaD model (Topside Sounder Model assisted by Digisonde) that makes possible the generation of maps of the electron density at heights up to GNSS orbits, and of TEC and partial TEC maps (topside and plasmaspheric) over Europe. The TaD is based on the simple empirical functions for the transition height, the topside electron density scale height and their ratio, based on the Alouette/ISIS database, and models separately the oxygen, hydrogen and helium ions density profiles. The model takes as input the plasma characteristics at the height of maximum electron concentration that are provided in real

  12. Cluster headaches.

    Science.gov (United States)

    Ryan, R E; Ryan, R E

    1989-12-01

    The patient with cluster headaches will be afflicted with the most severe type of pain that one will encounter. If the physician can do something to help this patient either by symptomatic or, more importantly, prophylactic treatment, he or she will have a most thankful patient. This type of headache is seen most frequently in men, and occurs in a cyclic manner. During an acute cycle, the patient will experience a daily type of pain that may occur many times per day. The pain is usually unilateral and may be accompanied by unilateral lacrimation, conjunctivitis, and clear rhinorrhea. Prednisone is the first treatment we employ. Patients are seen for follow-up approximately twice a week, and their medication is lowered in an appropriate manner, depending on their response to the treatment. Regulation of dosage has to be individualized, and when one reaches the lower dose such as 5 to 10 mg per day, the drug may have to be tapered more slowly, or even maintained at that level for a period of time to prevent further recurrence of symptoms. We frequently will use an intravenous histamine desensitization technique to prevent further attacks. We will give the patient an ergotamine preparation to use for symptomatic relief. As these patients often have headaches during the middle of the night, we will place the patient on a 2-mg ergotamine preparation to take prior to going to bed in the evening. This often works in a prophylactic nature, and prevents the nighttime occurrence of a headache. We believe that following these principles to make the accurate diagnosis and institute the proper therapy will help the practicing otolaryngologist recognize and treat patients suffering from this severe pain.

  13. Range safety signal propagation through the SRM exhaust plume of the space shuttle

    Science.gov (United States)

    Boynton, F. P.; Davies, A. R.; Rajasekhar, P. S.; Thompson, J. A.

    1977-01-01

    Theoretical predictions of plume interference for the space shuttle range safety system by solid rocket booster exhaust plumes are reported. The signal propagation was calculated using a split operator technique based upon the Fresnel-Kirchoff integral, using fast Fourier transforms to evaluate the convolution and treating the plume as a series of absorbing and phase-changing screens. Talanov's lens transformation was applied to reduce aliasing problems caused by ray divergence.

  14. A Lagrangian Approach to Studying Instantaneous Plume Dispersion and Concentration Fluctations

    Science.gov (United States)

    2007-11-02

    liquid PMCH from a reservoir (a medical IV bag), through a hypodermic needle , and onto a hotplate located within the duct. The temperature of the...plume theory in which time-averaged dispersion is the result of plume meander and relative plume diffusion (Gifford 1959). Wind data near release height...Science Degree will be completed in Environmental Engineering, 1998). Note: Mark only assisted in fieldwork and data analysis during one month of the

  15. Stennis Space Center's approach to liquid rocket engine health monitoring using exhaust plume diagnostics

    Science.gov (United States)

    Gardner, D. G.; Tejwani, G. D.; Bircher, F. E.; Loboda, J. A.; Van Dyke, D. B.; Chenevert, D. J.

    1991-01-01

    Details are presented of the approach used in a comprehensive program to utilize exhaust plume diagnostics for rocket engine health-and-condition monitoring and assessing SSME component wear and degradation. This approach incorporates both spectral and video monitoring of the exhaust plume. Video monitoring provides qualitative data for certain types of component wear while spectral monitoring allows both quantitative and qualitative information. Consideration is given to spectral identification of SSME materials and baseline plume emissions.

  16. The fine-scale vertical variability of a wastewater plume in shallow, stratified coastal waters

    Science.gov (United States)

    Lucas, Andrew J.; Kudela, Raphael M.

    2017-02-01

    We observed the fine-scale vertical variability of a wastewater plume discharged into shallow, stratified coastal waters with a set of wave-powered profiling moorings and bottom-mounted Acoustic Doppler Current Profilers. These in situ observations demonstrated that the effluent plume occupied a variable portion of the water column, but was typically at or above the pycnocline. The plume was characterized by small vertical scales away from the surface, while complicated patterns of vertical temperature and salinity compensation were found in the plume above the pycnocline. The particular design of the diffuser led to an effluent plume that was roughly split between depth-trapped and trapped at the surface. Estimates of dilution from temperature/salinity diagrams indicated that the plume dilution ranged between 60 and 120, and that the environmental mixing end-members ranged from waters well below the pycnocline to the waters at or near the surface. Far from the outfall, oceanographic variability at frequencies equal to and higher than the diurnal frequency dominated the vertical shear in local currents and thus the vertical and temporal distribution of the plume. Mixing driven by the high frequency non-linear internal waves and bore-like manifestations of the cross-shore baroclinic tide, as suggested by elevated inverse Richardson number within the leading and trailing edge of the bores, was likely the primary source of mixing between the plume and ambient waters far from the outfall. Complicated patterns in plume water characteristics demonstrated the complexity of the plume dilution even in a surfacing plume. The co-occurrence of elevated chlorophyll fluorescence and plume waters was evident in the later part of the diversion period, but the overall response of the phytoplankton to the effluent diversion was limited. Implications for outfall wastewater monitoring and diffuser design are briefly considered.

  17. Insights into the formation and dynamics of coignimbrite plumes from one-dimensional models

    Science.gov (United States)

    Engwell, S. L.; de'Michieli Vitturi, M.; Esposti Ongaro, T.; Neri, A.

    2016-06-01

    Coignimbrite plumes provide a common and effective mechanism by which large volumes of fine-grained ash are injected into the atmosphere. Nevertheless, controls on formation of these plumes as a function of eruptive conditions are still poorly constrained. Herein, two 1-D axysymmetric steady state models were coupled, the first describing the parent pyroclastic density current and the second describing plume rise. Global sensitivity analysis is applied to investigate controls on coignimbrite plume formation and describe coignimbrite source and the maximum plume height attained. For a range of initial mass flow rates between 108 and 1010 kg/s, modeled liftoff distance (the distance at which neutral buoyancy is attained), assuming radial supercritical flow, is controlled by the initial flow radius, gas mass fraction, flow thickness, and temperature. The predicted decrease in median grain size between flow initiation and plume liftoff is negligible. Calculated initial plume vertical velocities, assuming uniform liftoff velocity over the pyroclastic density current invasion area, are much greater (several tens of m/s) than those previously used in modeling coignimbrite plumes (1 m/s). Such velocities are inconsistent with the fine grain size of particles lofted into coignimbrite plumes, highlighting an unavailability of large clasts, possibly due to particle segregation within the flow, prior to plume formation. Source radius and initial vertical velocity have the largest effect on maximum plume height, closely followed by initial temperature. Modeled plume heights are between 25 and 47 km, comparable with Plinian eruption columns, highlighting the potential of such events for distributing fine-grained ash over significant areas.

  18. Phosphorus-bearing Aerosol Particles From Volcanic Plumes

    Science.gov (United States)

    Obenholzner, J. H.; Schroettner, H.; Poelt, P.; Delgado, H.; Caltabiano, T.

    2003-12-01

    Particles rich in P or bulk geochemical data of volcanic aerosol particles showing high P contents are known from many volcanic plumes (Stanton, 1994; Obenholzner et al., 2003). FESEM/EDS analysis of individual particles obtained from the passively degassing plume of Popocatepetl volcano, Mx. (1997) and from the plume of Stromboli (May 2003) show P frequently. Even at the high resolution of the FESEM, euhedral apatite crystals could not be observed. At Popocatepetl (1997) spherical Ca-P-O particles are common. Fluffy, fractal or botryoidal particles also can contain EDS-detectable amounts of P. The EDS spectrum of such particles can comprise various elements. However most particles show P, S and Cl. P-S and P-S-metal species are known in chemistry but do they occur in volcanic plumes? Stoichiometric considerations had been made in the past suggesting the existence of P-S species in plumes (Stanton 1994), gas sampling and remote gas monitoring systems have not detected yet such molecules in plumes. The particle spectrum of the reawakened Popocateptel volcano might be related to accumulation of volatiles at the top of a magma chamber during the phase of dormancy. P-Fe rich, Ca-free aggregates are also known from the eruption of El Chichon 1982 (SEM/EDS by M. Sheridan, per. comm. 08-24-2003). Persistently active volcanoes (i.e. Stromboli) represent a different category according to continuous degassing and aerosol particle formation. A particle collector ( ca. 90 ml/min) accompanied a COSPEC helicopter flight at Stromboli (May 15, 2003) after one of the rare types of sub-plinian events on April 5 2003. P-bearing particles are very common. For instance, an Fe oxide grain (diam. = 2 æm) is partially covered by fluffy and euhedral P-bearing matter. The elements detected are P, Cl, Na, Mg, Al, Si, K, Ca, Ti and (Fe). The fluffy and the euhedral (rhombohedral?) matter show in SE-BSE-mix image almost identical grey colors. At Stromboli and Popocatepetl particles on which

  19. CO2 plume management in saline reservoir sequestration

    Science.gov (United States)

    Frailey, S.M.; Finley, R.J.

    2011-01-01

    A significant difference between injecting CO2 into saline aquifers for sequestration and injecting fluids into oil reservoirs or natural gas into aquifer storage reservoirs is the availability and use of other production and injection wells surrounding the primary injection well(s). Of major concern for CO2 sequestration using a single well is the distribution of pressure and CO2 saturation within the injection zone. Pressure is of concern with regards to caprock integrity and potential migration of brine or CO2 outside of the injection zone, while CO2 saturation is of interest for storage rights and displacement efficiency. For oil reservoirs, the presence of additional wells is intended to maximize oil recovery by injecting CO2 into the same hydraulic flow units from which the producing wells are withdrawing fluids. Completing injectors and producers in the same flow unit increases CO2 throughput, maximizes oil displacement efficiency, and controls pressure buildup. Additional injectors may surround the CO2 injection well and oil production wells in order to provide external pressure to these wells to prevent the injected CO2 from migrating from the pattern between two of the producing wells. Natural gas storage practices are similar in that to reduce the amount of "cushion" gas and increase the amount of cycled or working gas, edge wells may be used for withdrawal of gas and center wells used for gas injection. This reduces loss of gas to the formation via residual trapping far from the injection well. Moreover, this maximizes the natural gas storage efficiency between the injection and production wells and reduces the areal extent of the natural gas plume. Proposed U.S. EPA regulations include monitoring pressure and suggest the "plume" may be defined by pressure in addition to the CO2 saturated area. For pressure monitoring, it seems that this can only be accomplished by injection zone monitoring wells. For pressure, these wells would not need to be very

  20. Methane oxidation in a crude oil contaminated aquifer: Delineation of aerobic reactions at the plume fringes

    Science.gov (United States)

    Amos, R.T.; Bekins, B.A.; Delin, G.N.; Cozzarelli, I.M.; Blowes, D.W.; Kirshtein, J.D.

    2011-01-01

    High resolution direct-push profiling over short vertical distances was used to investigate CH4 attenuation in a petroleum contaminated aquifer near Bemidji, Minnesota. The contaminant plume was delineated using dissolved gases, redox sensitive components, major ions, carbon isotope ratios in CH4 and CO2, and the presence of methanotrophic bacteria. Sharp redox gradients were observed near the water table. Shifts in ??13CCH4 from an average of - 57.6??? (?? 1.7???) in the methanogenic zone to - 39.6??? (?? 8.7???) at 105 m downgradient, strongly suggest CH4 attenuation through microbially mediated degradation. In the downgradient zone the aerobic/anaerobic transition is up to 0.5 m below the water table suggesting that transport of O2 across the water table is leading to aerobic degradation of CH4 at this interface. Dissolved N2 concentrations that exceeded those expected for water in equilibrium with the atmosphere indicated bubble entrapment followed by preferential stripping of O2 through aerobic degradation of CH4 or other hydrocarbons. Multivariate and cluster analysis were used to distinguish between areas of significant bubble entrapment and areas where other processes such as the infiltration of O 2 rich recharge water were important O2 transport mechanisms. ?? 2011 Elsevier B.V. All rights reserved.

  1. A multi-decadal history of biomass burning plume heights identified using aerosol index measurements

    Directory of Open Access Journals (Sweden)

    H. Guan

    2010-07-01

    Full Text Available We have quantified the relationship between Aerosol Index (AI measurements and plume height for young biomass burning plumes using coincident Ozone Monitoring Instrument (OMI and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO measurements. This linear relationship allows the determination of high-altitude plumes wherever AI data are available, and it provides a data set for validating global fire plume heights in chemistry transport models. We find that all plumes detected from June 2006 to February 2009 with an AI value ≥9 are located at altitudes higher than 5 km. Older high-altitude plumes have lower AI values than young plumes at similar altitudes. We have examined available AI data from the OMI and TOMS instruments (1978–2009 and find that large AI plumes occur more frequently over North America than over Australia or Russia/Northeast Asia. According to the derived relationship, during this time interval, 181 plumes, in various stages of their evolution, reached altitudes above 8 km.

  2. Wind relaxation and a coastal buoyant plume north of Pt. Conception, CA: Observations, simulations, and scalings

    Science.gov (United States)

    Suanda, Sutara H.; Kumar, Nirnimesh; Miller, Arthur J.; Di Lorenzo, Emanuele; Haas, Kevin; Cai, Donghua; Edwards, Christopher A.; Washburn, Libe; Fewings, Melanie R.; Torres, Rachel; Feddersen, Falk

    2016-10-01

    In upwelling regions, wind relaxations lead to poleward propagating warm water plumes that are important to coastal ecosystems. The coastal ocean response to wind relaxation around Pt. Conception, CA is simulated with a Regional Ocean Model (ROMS) forced by realistic surface and lateral boundary conditions including tidal processes. The model reproduces well the statistics of observed subtidal water column temperature and velocity at both outer and inner-shelf mooring locations throughout the study. A poleward-propagating plume of Southern California Bight water that increases shelf water temperatures by ≈ 5°C is also reproduced. Modeled plume propagation speed, spatial scales, and flow structure are consistent with a theoretical scaling for coastal buoyant plumes with both surface-trapped and slope-controlled dynamics. Plume momentum balances are distinct between the offshore (>30 m depth) region where the plume is surface-trapped, and onshore of the 30 m isobath (within 5 km from shore) where the plume water mass extends to the bottom and is slope controlled. In the onshore region, bottom stress is important in the alongshore momentum equation and generates vertical vorticity that is an order of magnitude larger than the vorticity in the plume core. Numerical experiments without tidal forcing show that modeled surface temperatures are biased 0.5°C high, potentially affecting plume propagation distance and persistence.

  3. Resonant holographic measurements of laser ablation plume expansion in vacuum and argon gas backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Lindley, R.A. [Michigan Univ., Ann Arbor, MI (United States)

    1993-10-01

    This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser bandwidth; The solution for doppler broadening and finite bandwidth; the main optical table; the lumonics laser spot shape; developing and reconstructing the holograms; plume expansion in RF/Plasma Environments; Determining {lambda}{sub o}; resonant refraction effects; fringe shift interpretation; shot-to-shot consistency; laser ablation in vacuum and low pressure, inert, background gas; theoretically modeling plume expansion in vacuum and low pressure, inert, background gas; and laser ablation in higher pressure, inert, background gas.

  4. Orion Service Module Reaction Control System Plume Impingement Analysis Using PLIMP/RAMP2

    Science.gov (United States)

    Wang, Xiao-Yen; Lumpkin, Forrest E., III; Gati, Frank; Yuko, James R.; Motil, Brian J.

    2009-01-01

    The Orion Crew Exploration Vehicle Service Module Reaction Control System engine plume impingement was computed using the plume impingement program (PLIMP). PLIMP uses the plume solution from RAMP2, which is the refined version of the reacting and multiphase program (RAMP) code. The heating rate and pressure (force and moment) on surfaces or components of the Service Module were computed. The RAMP2 solution of the flow field inside the engine and the plume was compared with those computed using GASP, a computational fluid dynamics code, showing reasonable agreement. The computed heating rate and pressure using PLIMP were compared with the Reaction Control System plume model (RPM) solution and the plume impingement dynamics (PIDYN) solution. RPM uses the GASP-based plume solution, whereas PIDYN uses the SCARF plume solution. Three sets of the heating rate and pressure solutions agree well. Further thermal analysis on the avionic ring of the Service Module was performed using MSC Patran/Pthermal. The obtained temperature results showed that thermal protection is necessary because of significant heating from the plume.

  5. Plume and surface feature structure and compositional effects on Europa's global exosphere: Preliminary Europa mission predictions

    Science.gov (United States)

    Teolis, B. D.; Wyrick, D. Y.; Bouquet, A.; Magee, B. A.; Waite, J. H.

    2017-03-01

    A Europa plume source, if present, may produce a global exosphere with complex spatial structure and temporal variability in its density and composition. To investigate this interaction we have integrated a water plume source containing multiple organic and nitrile species into a Europan Monte Carlo exosphere model, considering the effect of Europa's gravity in returning plume ejecta to the surface, and the subsequent spreading of adsorbed and exospheric material by thermal desorption and re-sputtering across the entire body. We consider sputtered, radiolytic and potential plume sources, together with surface adsorption, regolith diffusion, polar cold trapping, and re-sputtering of adsorbed materials, and examine the spatial distribution and temporal evolution of the exospheric density and composition. These models provide a predictive basis for telescopic observations (e.g. HST, JWST) and planned missions to the Jovian system by NASA and ESA. We apply spacecraft trajectories to our model to explore possible exospheric compositions which may be encountered along proposed flybys of Europa to inform the spatial and temporal relationship of spacecraft measurements to surface and plume source compositions. For the present preliminary study, we have considered four cases: Case A: an equatorial flyby through a sputtered only exosphere (no plumes), Case B: a flyby over a localized sputtered 'macula' terrain enriched in non-ice species, Case C: a south polar plume with an Enceladus-like composition, equatorial flyby, and Case D: a south polar plume, flyby directly through the plume.

  6. Imaging trace gases in volcanic plumes with Fabry Perot Interferometers

    Science.gov (United States)

    Kuhn, Jonas; Platt, Ulrich; Bobrowski, Nicole; Lübcke, Peter; Wagner, Thomas

    2017-04-01

    Within the last decades, progress in remote sensing of atmospheric trace gases revealed many important insights into physical and chemical processes in volcanic plumes. In particular, their evolution could be studied in more detail than by traditional in-situ techniques. A major limitation of standard techniques for volcanic trace gas remote sensing (e.g. Differential Optical Absorption Spectroscopy, DOAS) is the constraint of the measurement to a single viewing direction since they use dispersive spectroscopy with a high spectral resolution. Imaging DOAS-type approaches can overcome this limitation, but become very time consuming (of the order of minutes to record a single image) and often cannot match the timescales of the processes of interest for volcanic gas measurements (occurring at the order of seconds). Spatially resolved imaging observations with high time resolution for volcanic sulfur dioxide (SO2) emissions became possible with the introduction of the SO2-Camera. Reducing the spectral resolution to two spectral channels (using interference filters) that are matched to the SO2 absorption spectrum, the SO2-Camera is able to record full frame SO2 slant column density distributions at a temporal resolution on the order of BrO) and chlorine dioxide (OClO) both yield absorption features that allow their detection with the FPI correlation technique. From BrO and OClO data, ClO levels in the plume could be calculated. We present an outline of applications of the FPI technique to imaging a series of trace gases in volcanic plumes. Sample calculations on the sensitivity and selectivity of the technique, first proof of concept studies and proposals for technical implementations are presented.

  7. Groundwater-quality data for a treated-wastewater plume near the Massachusetts Military Reservation, Ashumet Valley, Cape Cod, Massachusetts, 2006-08

    Science.gov (United States)

    Savoie, Jennifer G.; LeBlanc, Denis R.; Fairchild, Gillian M.; Smith, Richard L.; Kent, Douglas B.; Barber, Larry B.; Repert, Deborah A.; Hart, Charles P.; Keefe, Steffanie H.; Parsons, Luke A.

    2012-01-01

    A plume of contaminated groundwater extends from former disposal beds at the Massachusetts Military Reservation's wastewater-treatment plant toward Ashumet Pond, coastal ponds, and Vineyard Sound, Cape Cod, Massachusetts. Treated sewage-derived wastewater was discharged to the rapid-infiltration beds for nearly 60 years before the disposal site was moved to a different location in December 1995. Water-quality samples were collected from monitoring wells, multilevel samplers, and profile borings to characterize the nature and extent of the contaminated groundwater and to observe the water-quality changes after the wastewater disposal ceased. Data are presented here for water samples collected in 2007 from 394 wells (at 121 well-cluster locations) and 780 multilevel-sampler ports (at 42 locations) and in 2006-08 at 306 depth intervals in profile borings (at 20 locations) in and near the treated-wastewater plume. Analyses of these water samples for field parameters (specific conductance, pH, dissolved oxygen and phosphate concentrations, and alkalinity); absorbance of ultraviolet/visible light; and concentrations of nitrous oxide, dissolved organic carbon, methylene blue active substances, selected anions and nutrients, including nitrate and ammonium, and selected inorganic solutes, including cations, anions, and minor elements, are presented in tabular format. The natural restoration of the sand and gravel aquifer after removal of the treated-wastewater source, along with interpretations of the water quality in the treated-wastewater plume, have been documented in several published reports that are listed in the references.

  8. Factorial PD-Clustering

    CERN Document Server

    Tortora, Cristina; Summa, Mireille Gettler

    2011-01-01

    Factorial clustering methods have been developed in recent years thanks to the improving of computational power. These methods perform a linear transformation of data and a clustering on transformed data optimizing a common criterion. Factorial PD-clustering is based on Probabilistic Distance clustering (PD-clustering). PD-clustering is an iterative, distribution free, probabilistic, clustering method. Factorial PD-clustering make a linear transformation of original variables into a reduced number of orthogonal ones using a common criterion with PD-Clustering. It is demonstrated that Tucker 3 decomposition allows to obtain this transformation. Factorial PD-clustering makes alternatively a Tucker 3 decomposition and a PD-clustering on transformed data until convergence. This method could significantly improve the algorithm performance and allows to work with large dataset, to improve the stability and the robustness of the method.

  9. Correlated patterns in hydrothermal plume distribution and apparent magmatic budget along 2500 km of the Southeast Indian Ridge

    Science.gov (United States)

    Baker, Edward T.; Hémond, Christophe; Briais, Anne; Maia, Marcia; Scheirer, Daniel S.; Walker, Sharon L.; Wang, Tingting; Chen, Yongshun John

    2014-08-01

    geological processes affect the distribution of hydrothermal venting along a mid-ocean ridge. Deciphering the role of a specific process is often frustrated by simultaneous changes in other influences. Here we take advantage of the almost constant spreading rate (65-71 mm/yr) along 2500 km of the Southeast Indian Ridge (SEIR) between 77°E and 99°E to examine the spatial density of hydrothermal venting relative to regional and segment-scale changes in the apparent magmatic budget. We use 227 vertical profiles of light backscatter and (on 41 profiles) oxidation-reduction potential along 27 first and second-order ridge segments on and adjacent to the Amsterdam-St. Paul (ASP) Plateau to map ph, the fraction of casts detecting a plume. At the regional scale, venting on the five segments crossing the magma-thickened hot spot plateau is almost entirely suppressed (ph = 0.02). Conversely, the combined ph (0.34) from all other segments follows the global trend of ph versus spreading rate. Off the ASP Plateau, multisegment trends in ph track trends in the regional axial depth, high where regional depth increases and low where it decreases. At the individual segment scale, a robust correlation between ph and cross-axis inflation for first-order segments shows that different magmatic budgets among first-order segments are expressed as different levels of hydrothermal spatial density. This correlation is absent among second-order segments. Eighty-five percent of the plumes occur in eight clusters totaling ˜350 km. We hypothesize that these clusters are a minimum estimate of the length of axial melt lenses underlying this section of the SEIR.

  10. Mapping organic contaminant plumes in groundwater using spontaneous potentials

    Science.gov (United States)

    Forte, Sarah

    Increased water demands have raised awareness of its importance. One of the challenges facing water resource management is dealing with contaminated groundwater; delineating, characterizing and remediating it. In the last decade, spontaneous potentials have been proposed as a method for delineating degrading organic contaminant plumes in groundwater. A hypothesis proposed that the redox potential gradient due to degradation of contaminants generated an electrical potential gradient that could be measured at the ground surface. This research was undertaken to better understand this phenomenon and find under what conditions it occurs. Spontaneous potentials are electrical potentials generated by three sources that act simultaneously: electrokinetic, thermoelectric and electrochemical sources. Over contaminant plumes electrochemical sources are those of interest. Thermoelectric sources are negligible unless in geothermal areas, but we hypothesized that electrokinetic potentials could be impacted by contaminants altering sediment surface properties. We built and calibrated a laboratory apparatus to make measurements that allowed us to calculate streaming current coupling coefficients. We tested sediment from hydrocarbon impacted sites with clean and hydrocarbon polluted groundwater and found a measurable though inconsistent effect. Moreover, numerical modelling was used to demonstrate that the impact of these changes on field measurements was negligible. Spontaneous potential surveys were conducted on two field sites with well characterized degrading hydrocarbon plumes in groundwater. We did not find a correlation between redox conditions and spontaneous potential, even after the electrical measurements were corrected for anthropogenic noise. In order to determine why the expected signal was not seen, we undertook numerical modelling based on coupled fluxes using two hypothesized types of current: redox and diffusion currents. The only scenarios that produced

  11. Plasma Diagnostic in laser ablation plumes for isotope separation applications

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Juliana B. de [Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil)]. E-mail: juliana@ieav.cta.br; Rodrigues, Nicolau A.S.; Neri, Jose W.; Silveira, Carlos A.B. [Instituto de Estudos Avancados (IEAv/EFO), Sao Jose dos Campos, SP (Brazil). Div. de Fotonica

    2008-07-01

    The plasma plume produced in vacuum by ablation of copper, aluminum and tungsten samples, illuminated by copper laser pulses, was investigated. A Langmuir probe was used to study the macroscopic parameters electron number density (Ne) and electron temperature (Te). Plasma expansion velocity (Vp) was also investigated and it was studied the dependence of these parameters with the laser irradiance. Typical values are respectively N{sub e} {approx} 10{sup 8}-10{sup 9}/cm{sup 3}, T{sub e} {approx} 15 eV and Vp {approx} 10 km/s. (author)

  12. Effect of nozzle geometry on the resistojet exhaust plume

    Science.gov (United States)

    Breyley, Loranell; Serafini, John S.; Hoffman, David J.; Zana, Lynette M.

    1987-01-01

    Five nozzle configurations were used to study the effect of geometry on the plume structure of a resistojet exhausting into a vacuum. Mass flux data in the forward and back flux regions were obtained with a cryogenically cooled quartz crystal microbalance. The propellant used was CO2 at 300 K and a mass flow rate of 0.2 g/s. The data reveal that the percent of mass flow contained within half angles of 10, 30, and 40 deg varied by less than 12 percent from a standard 20 deg half-angle cone nozzle.

  13. What Causes Aerosol Growth and Ozone Production in Smoke Plumes?

    Science.gov (United States)

    Alvarado, M. J.; Prinn, R. G.

    2006-12-01

    The growth of aerosol particles and production of ozone in smoke plumes is the result of a complex interaction between horizontal diffusion, gas-phase oxidation, coagulation, and mass transfer between phases. Models allow us to separate the effects of these processes and predict their impact on the global environment. We present the results of a new model of gas and aerosol chemistry applied to young biomass burning plumes. The model includes heterogeneous chemistry, kinetic mass transfer, coagulation and the formation of secondary organic and inorganic aerosol. Comparison with measurements from SAFARI 2000 (Hobbs et al., 2003, JGR, doi:10.1029/2002JD002352) suggests the baseline model underpredicts ozone formation and the growth of aerosol within the plume. We explore whether the model predictions can be improved by (1) including heterogeneous HONO production, and (2) adding in surrogates for the uncharacterized organic compounds emitted by the biomass burning. Including the heterogeneous reaction NO2 => HONO greatly improves the match for ozone, OH, and aerosol nitrate concentration, but only when the uptake coefficient approaches 10-3, which is over an order of magnitude higher than previously reported values (Stemmler et al., 2006, doi:10.1038/nature04603). Using the reaction NO2 => 0.5 HONO + 0.5 HNO3 with an uptake coefficient of 10-3 (the top of the range recommended by Jacob, 2000, Atm. Env.,34, 2131-2159) provides an even better match for aerosol nitrate, but produces less O3 and OH than the first reaction. Direct measurements of HONO and OH in young biomass plumes would help determine if this chemistry is taking place. We used two surrogates to model the uncharacterized compounds: long chain alkanes and monoterpenes, representing primary and secondary sources of condensable compounds respectively. Complete condensation of the long-chain alkanes can account for nearly all of the observed increase in organic carbon. However, the accommodation coefficient

  14. Laser pointing in the vicinity of jet engine plumes

    Science.gov (United States)

    Schleijpen, Ric H. M. A.

    2009-09-01

    Target tracking and laser-based pointing from airborne platforms can be degraded significantly by the propagation environment around an airborne platform including zones of severe turbulence generated by rotor downwash and engine exhausts. This is the topic of the EDA study group ERG 108.019 on "Laser beam propagation and imaging through severe environments". This paper reports on experiments on optical propagation in the vicinity of a plume of a scaled down jet engine, performed by this co-operation group. The group is also working on methods for estimating the extent of the turbulence effects on the tracking and pointing performance under these conditions.

  15. Exhaust Plume Measurements of the VASIMR VX-200

    Science.gov (United States)

    Longmier, Benjamin; Bering, Edgar, III; Squire, Jared; Glover, Tim; Chang-Diaz, Franklin; Brukardt, Michael

    2008-11-01

    Recent progress is discussed in the development of an advanced RF electric propulsion concept: the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) VX-200 engine, a 200 kW flight-technology prototype. Results from high power Helicon only and Helicon with ICRH experiments are performed on the VX-200 using argon plasma. Recent measurements of axial plasma density and potential profiles, magnetic field-line shaping, charge exchange, and force measurements taken in the plume of the VX-200 exhaust are made within a new 125 cubic meter cryo-pumped vacuum chamber and are presented in the context of RF plasma thruster physics.

  16. Integrated characterisation of aquifer heterogeneity and landfill leachate plume migration

    Science.gov (United States)

    Tremblay, L.; Lefebvre, R.; Gloaguen, E.; Paradis, D.

    2009-05-01

    The understanding of groundwater flow and contaminant migration is based on our ability to characterize aquifers and represent these processes with numerical simulators. This understanding is required to efficiently remediate contaminated sites since the failure of remediation actions are often related to an insufficient understanding of aquifer heterogeneity. During the last decades, continuous development of numerical simulators allowed models to better represent complex flow systems. However, conventional hydrogeological characterization methods do not provide the data required to define aquifer heterogeneity. An original hydrogeological characterization approach was used to define aquifer heterogeneity and delineate landfill leachate plumes through the use and integration of varied techniques. The objective of the study is to develop a methodology to integrate hydrogeological, geophysical and geochemical data using geostatistical tools. The characterization program aims to better characterize the aquifer, delineate leachate plumes emitted by a former landfill, and guide a study of the natural attenuation of the plumes. The initial phase of the integrated multidisciplinary aquifer characterization program was carried out in a 12 km2 area of the sub-watershed surrounding the landfill of St-Lambert-de-Lauzon, Québec. In the study area, a 10-m thick sandy unconfined aquifer overlies clayey silt and till layers. In this relatively flat area, natural streams as well as agricultural and forestry drainage networks control groundwater flow. The first phase of the project focused on a regional hydrogeological and geochemical characterization where 5 field methods were combined: 1) surface geophysics (ground penetrating radar and electrical tomography) (GPR); 2) direct-push methods including a) cone penetration tests (CPT), b) soil sampling and c) installation of full- screened observation wells; 3) multilevel measurement of geochemical parameters and groundwater

  17. A mantle plume below the Eifel volcanic fields, Germany

    OpenAIRE

    Ritter, Joachim R. R.; Jordan, Michael; Christensen, Ulrich R.; Achauer, Ulrich

    2001-01-01

    We present seismic images of the upper mantle below the Quaternary Eifel volcanic fields, Germany, determined by teleseismic travel time tomography. The data were measured at a dedicated network of more than 200 stations. Our results show a columnar low P-velocity anomaly in the upper mantle with a lateral contrast of up to 2%. The 100 km wide structure extends to at least 400 km depth and is equivalent to about 150–200 K excess temperature. This clear evidence for a plume below a region of c...

  18. Possibilistic Exponential Fuzzy Clustering

    Institute of Scientific and Technical Information of China (English)

    Kiatichai Treerattanapitak; Chuleerat Jaruskulchai

    2013-01-01

    Generally,abnormal points (noise and outliers) cause cluster analysis to produce low accuracy especially in fuzzy clustering.These data not only stay in clusters but also deviate the centroids from their true positions.Traditional fuzzy clustering like Fuzzy C-Means (FCM) always assigns data to all clusters which is not reasonable in some circumstances.By reformulating objective function in exponential equation,the algorithm aggressively selects data into the clusters.However noisy data and outliers cannot be properly handled by clustering process therefore they are forced to be included in a cluster because of a general probabilistic constraint that the sum of the membership degrees across all clusters is one.In order to improve this weakness,possibilistic approach relaxes this condition to improve membership assignment.Nevertheless,possibilistic clustering algorithms generally suffer from coincident clusters because their membership equations ignore the distance to other clusters.Although there are some possibilistic clustering approaches that do not generate coincident clusters,most of them require the right combination of multiple parameters for the algorithms to work.In this paper,we theoretically study Possibilistic Exponential Fuzzy Clustering (PXFCM) that integrates possibilistic approach with exponential fuzzy clustering.PXFCM has only one parameter and not only partitions the data but also filters noisy data or detects them as outliers.The comprehensive experiments show that PXFCM produces high accuracy in both clustering results and outlier detection without generating coincident problems.

  19. Four-point high time resolution information on electron densities by the electric field experiments (EFW on Cluster

    Directory of Open Access Journals (Sweden)

    A. Pedersen

    Full Text Available For accurate measurements of electric fields, spherical double probes are electronically controlled to be at a positive potential of approximately 1 V relative to the ambient magnetospheric plasma. The spacecraft will acquire a potential which balances the photoelectrons escaping to the plasma and the electron flux collected from the plasma. The probe-to-plasma potential difference can be measured with a time resolution of a fraction of a second, and provides information on the electron density over a wide range of electron densities from the lobes (~ 0.01 cm-3 to the magnetosheath (>10 cm-3 and the plasmasphere (>100 cm-3. This technique has been perfected and calibrated against other density measurements on GEOS, ISEE-1, CRRES, GEOTAIL and POLAR. The Cluster spacecraft potential measurements opens the way for new approaches, particularly near boundaries and gradients where four-point measurements will provide information never obtained before. Another interesting point is that onboard data storage of this simple parameter can be done for complete orbits and thereby will provide background information for the shorter full data collection periods on Cluster. Preliminary calibrations against other density measurements on Cluster will be reported.

    Key words. Magnetospheric physics (magnetopause, cusp, and boundary layers Space plasma physics (spacecraft sheaths, wakes, charging; instruments and techniques

  20. High resolution mapping of hydrothermal plumes in the Mariana back-arc relate seafloor sources to above-bottom plumes

    Science.gov (United States)

    Walker, S. L.; Baker, E. T.; Resing, J. A.; Chadwick, W. W., Jr.; Merle, S. G.; Kaiser, C. L.

    2016-12-01

    The Mariana backarc spreading center between 12.9°-18°N was systematically explored for hydrothermal activity in Nov-Dec 2015 (R/V Falkor cruise FK151121) by conducting long distance along-axis CTD tows (vertical range was 20-600 meters above bottom (mab)) followed by higher resolution, horizontal grid AUV Sentry surveys at 70 mab in some of the areas where plumes were found. In those areas, the combination of along-axis CTD tows and near-bottom AUV surveys provides a nearly 3-dimensional view of the above-bottom plume relative to the seafloor morphology and potential sources. In addition, photo surveys were run at 5 mab at two of the sites. At 15.4°N, strong ORP anomalies (ΔE=-39 mv) with weak to absent optical signals were aligned with a new (ROV dives in May 2016. At 18°N, anomalies seen in the 11 km2 AUV survey were generally located along the axis of the spreading center and, with one exception, were limited to areas of previously-known (1987) venting. The plume in the water column over the Burke vent site was defined by both particle (dNTU=0.010) and ORP (ΔE=-11 mv) anomalies from 400-800 mab, but only ORP signals 120-400 mab. ORP signals were seen over the other sites without any optical anomalies; the much lower rise heights (200-400 mab) suggest only lower temperature, diffuse venting persists at these sites.