WorldWideScience

Sample records for wind ism cloud interactions

  1. A comparison of shock-cloud and wind-cloud interactions: the longer survival of clouds in winds

    Science.gov (United States)

    Goldsmith, K. J. A.; Pittard, J. M.

    2017-09-01

    The interaction of a hot, high-velocity wind with a cold, dense molecular cloud has often been assumed to resemble the evolution of a cloud embedded in a post-shock flow. However, no direct comparative study of these two processes currently exists in the literature. We present 2D adiabatic hydrodynamical simulations of the interaction of a Mach 10 shock with a cloud of density contrast χ = 10 and compare our results with those of a commensurate wind-cloud simulation. We then investigate the effect of varying the wind velocity, effectively altering the wind Mach number Mwind, on the cloud's evolution. We find that there are significant differences between the two processes: 1) the transmitted shock is much flatter in the shock-cloud interaction; 2) a low-pressure region in the wind-cloud case deflects the flow around the edge of the cloud in a different manner to the shock-cloud case; 3) there is far more axial compression of the cloud in the case of the shock. As Mwind increases, the normalized rate of mixing is reduced. Clouds in winds with higher Mwind also do not experience a transmitted shock through the cloud's rear and are more compressed axially. In contrast with shock-cloud simulations, the cloud mixing time normalized by the cloud-crushing time-scale tcc increases for increasing Mwind until it plateaus (at tmix ≃ 25 tcc) at high Mwind, thus demonstrating the expected Mach scaling. In addition, clouds in high Mach number winds are able to survive for long durations and are capable of being moved considerable distances.

  2. Filament formation in wind-cloud interactions- II. Clouds with turbulent density, velocity, and magnetic fields

    Science.gov (United States)

    Banda-Barragán, W. E.; Federrath, C.; Crocker, R. M.; Bicknell, G. V.

    2018-01-01

    We present a set of numerical experiments designed to systematically investigate how turbulence and magnetic fields influence the morphology, energetics, and dynamics of filaments produced in wind-cloud interactions. We cover 3D, magnetohydrodynamic systems of supersonic winds impacting clouds with turbulent density, velocity, and magnetic fields. We find that lognormal density distributions aid shock propagation through clouds, increasing their velocity dispersion and producing filaments with expanded cross-sections and highly magnetized knots and subfilaments. In self-consistently turbulent scenarios, the ratio of filament to initial cloud magnetic energy densities is ∼1. The effect of Gaussian velocity fields is bound to the turbulence Mach number: Supersonic velocities trigger a rapid cloud expansion; subsonic velocities only have a minor impact. The role of turbulent magnetic fields depends on their tension and is similar to the effect of radiative losses: the stronger the magnetic field or the softer the gas equation of state, the greater the magnetic shielding at wind-filament interfaces and the suppression of Kelvin-Helmholtz instabilities. Overall, we show that including turbulence and magnetic fields is crucial to understanding cold gas entrainment in multiphase winds. While cloud porosity and supersonic turbulence enhance the acceleration of clouds, magnetic shielding protects them from ablation and causes Rayleigh-Taylor-driven subfilamentation. Wind-swept clouds in turbulent models reach distances ∼15-20 times their core radius and acquire bulk speeds ∼0.3-0.4 of the wind speed in one cloud-crushing time, which are three times larger than in non-turbulent models. In all simulations, the ratio of turbulent magnetic to kinetic energy densities asymptotes at ∼0.1-0.4, and convergence of all relevant dynamical properties requires at least 64 cells per cloud radius.

  3. LACIS-T - A humid wind tunnel for investigating the Interactions between Cloud Microphysics and Turbulence

    Science.gov (United States)

    Voigtländer, Jens; Niedermeier, Dennis; Siebert, Holger; Shaw, Raymond; Schumacher, Jörg; Stratmann, Frank

    2017-04-01

    To improve the fundamental and quantitative understanding of the interactions between cloud microphysical and turbulent processes, the Leibniz Institute for Tropospheric Research (TROPOS) has built up a new humid wind tunnel (LACIS-T). LACIS-T allows for the investigation of cloud microphysical processes, such as cloud droplet activation and freezing, under-well defined thermodynamic and turbulent flow conditions. It therewith allows for the straight forward continuation, extension, and completion of the cloud microphysics related investigations carried out at the Leipzig Aerosol Cloud Interaction Simulator (LACIS) under laminar flow conditions. Characterization of the wind tunnel with respect to flow, thermodynamics, and droplet microphysics is carried out with probes mounted inside (pitot tube and hot-wire anemometer for mean velocity and fluctuations, Pt100 sensor for mean temperature, cold-wire sensor for temperature fluctuations is in progress, as well as a dew-point mirror for mean water vapor concentration, a Lyman-alpha sensor for water vapor fluctuations is in progress) the measurement section, and from outside with optical detection methods (a laser light sheet is available for cloud droplet visualization, a digital holography system for detection of cloud droplet size distributions will be installed for tests in February 2017), respectively. Computational fluid dynamics (CFD) simulations have been carried out for defining suitable experimental conditions and assisting the interpretation of the experimental data. In this work, LACIS-T, its fundamental operating principle, and first preliminary results from ongoing characterization efforts will be presented.

  4. Winds and radiation in unison: a new semi-analytic feedback model for cloud dissolution

    Science.gov (United States)

    Rahner, Daniel; Pellegrini, Eric W.; Glover, Simon C. O.; Klessen, Ralf S.

    2017-10-01

    Star clusters interact with the interstellar medium (ISM) in various ways, most importantly in the destruction of molecular star-forming clouds, resulting in inefficient star formation on galactic scales. On cloud scales, ionizing radiation creates H II regions, while stellar winds and supernovae (SNe) drive the ISM into thin shells. These shells are accelerated by the combined effect of winds, radiation pressure, and SN explosions, and slowed down by gravity. Since radiative and mechanical feedback is highly interconnected, they must be taken into account in a self-consistent and combined manner, including the coupling of radiation and matter. We present a new semi-analytic 1D feedback model for isolated massive clouds (≥105 M⊙) to calculate shell dynamics and shell structure simultaneously. It allows us to scan a large range of physical parameters (gas density, star formation efficiency, and metallicity) and to estimate escape fractions of ionizing radiation fesc, I, the minimum star formation efficiency ɛmin required to drive an outflow, and recollapse time-scales for clouds that are not destroyed by feedback. Our results show that there is no simple answer to the question of what dominates cloud dynamics, and that each feedback process significantly influences the efficiency of the others. We find that variations in natal cloud density can very easily explain differences between dense-bound and diffuse-open star clusters. We also predict, as a consequence of feedback, a 4-6 Myr age difference for massive clusters with multiple generations.

  5. Superluminous Transients at AGN Centers from Interaction between Black Hole Disk Winds and Broad-line Region Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Moriya, Takashi J.; Tanaka, Masaomi; Ohsuga, Ken [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Morokuma, Tomoki, E-mail: takashi.moriya@nao.ac.jp [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

    2017-07-10

    We propose that superluminous transients that appear at central regions of active galactic nuclei (AGNs) such as CSS100217:102913+404220 (CSS100217) and PS16dtm, which reach near- or super-Eddington luminosities of the central black holes, are powered by the interaction between accretion-disk winds and clouds in broad-line regions (BLRs) surrounding them. If the disk luminosity temporarily increases by, e.g., limit–cycle oscillations, leading to a powerful radiatively driven wind, strong shock waves propagate in the BLR. Because the dense clouds in the AGN BLRs typically have similar densities to those found in SNe IIn, strong radiative shocks emerge and efficiently convert the ejecta kinetic energy to radiation. As a result, transients similar to SNe IIn can be observed at AGN central regions. Since a typical black hole disk-wind velocity is ≃0.1 c , where c is the speed of light, the ejecta kinetic energy is expected to be ≃10{sup 52} erg when ≃1 M {sub ⊙} is ejected. This kinetic energy is transformed to radiation energy in a timescale for the wind to sweep up a similar mass to itself in the BLR, which is a few hundred days. Therefore, both luminosities (∼10{sup 44} erg s{sup −1}) and timescales (∼100 days) of the superluminous transients from AGN central regions match those expected in our interaction model. If CSS100217 and PS16dtm are related to the AGN activities triggered by limit–cycle oscillations, they become bright again in coming years or decades.

  6. Polarization signatures of bow shocks: A diagnostic tool to constrain the properties of stellar winds and ISM

    Science.gov (United States)

    Shrestha, Manisha; Hoffman, Jennifer L.; Nielson, Hilding R.; Ignace, Richard

    2017-01-01

    When a stellar wind traveling at supersonic speed interacts with almost stationary ISM, a bow shock shape is formed. By studying a bow shock, we can obtain information about the properties of the stellar wind as well as the surrounding ISM. Bow shocks are asymmetric structures, and thus produce net polarization even if they are unresolved. Hence, polarization studies of bow shocks can provide complementary constraints on their properties.We simulate the polarization signatures of circumstellar material with bow shock geometries using a Monte Carlo radiative transfer code called SLIP. We use the analytic solution from Wilkin (1996) to define the geometry and mass surface density of the bow shock in our models. We present results from our simulations showing how changing CSM optical depth, CSM albedo, photon source, and scattering particles (electrons or different types of dust particles) affects the observed polarization in both resolved and unresolved cases. In the optically thin regime of the unresolved electron-scattering case, the polarization peaks at an inclination angle of 90°, in agreement with analytical single-scattering models. In optically thick cases, a second polarization peak appears near 130°, which we propose is due to multiple scattering. Given these results, an observed polarization value can constrain the inclination of an unresolved bow shock to two possible angles, which in turn constrain the motion of the star. In case of resolved bow shocks, our simulations produce polarization maps which we compare with observations.We also present results from our dust-scattering simulations, which show that multicolor broadband polarization observations can constrain the characteristics of the dust in a resolved or unresolved bow shock-shaped CSM configuration.

  7. Prevention of accretion onto white dwarfs by stellar winds

    Science.gov (United States)

    Macdonald, James

    1992-01-01

    There is indirect observational evidence that hot white dwarfs may have weak stellar winds. In this paper, the interaction between such a wind and the flow of ISM material in the gravitational field of the white dwarf is investigated with the aim of finding limits on the mass-loss rate and terminal velocity of winds capable of preventing accretion from the ISM. The limiting cases of no relative motion of the star and the ISM and supersonic relative motion of the star through ISM are separately investigated. Each case is treated by generalizing models for the interaction between the solar wind and the local ISM to include the effects of gravity. It is found that, for wind velocities expected for radiatively driven winds, mass-loss rates as low as 10 exp -21 solar mass/yr are sufficient to prevent accretion from the hot phase of the ISM. To prevent accretion during passages through cold clouds, wind mass-loss rates of order 10 exp -18 to 10 exp -17 are required.

  8. Theoretical Description of GRB 160625B with Wind-to-ISM Transition and Implications for a Magnetized Outflow

    Science.gov (United States)

    Fraija, N.; Veres, P.; Zhang, B. B.; Barniol Duran, R.; Becerra, R. L.; Zhang, B.; Lee, W. H.; Watson, A. M.; Ordaz-Salazar, C.; Galvan-Gamez, A.

    2017-10-01

    GRB 160625B, one of the brightest bursts in recent years, was simultaneously observed by Fermi and Swift satellites, and ground-based optical telescopes in three different events separated by long periods of time. In this paper, the non-thermal multiwavelength observations of GRB 160625B are described and a transition phase from wind-type-like medium to interstellar medium (ISM) between the early (event II) and the late (event III) afterglow is found. The multiwavelength observations of the early afterglow are consistent with the afterglow evolution starting at ∼150 s in a stellar wind medium, whereas the observations of the late afterglow are consistent with the afterglow evolution in ISM. The wind-to-ISM transition is calculated to be at ∼ 8× {10}3 s when the jet has decelerated, at a distance of ∼1 pc from the progenitor. Using the standard external shock model, the synchrotron and synchrotron self-Compton emission from reverse shock is required to model the GeV γ-ray and optical observations in the early afterglow, and synchrotron radiation from the adiabatic forward shock to describe the X-ray and optical observations in the late afterglow. The derived values of the magnetization parameter, the slope of the fast decay of the optical flash, and the inferred magnetic fields suggest that Poynting flux-dominated jet models with arbitrary magnetization could account for the spectral properties exhibited by GRB 160625B.

  9. Hydrodynamic interaction of SNR shocks with thermally conducting, radiative clouds .

    Science.gov (United States)

    Orlando, S.; Peres, G.; Reale, F.; Bocchino, F.; Plewa, T.; Rosner, R.

    Supernova remnants (SNRs) are privileged laboratories to investigate the physical and chemical evolution of the galactic interstellar medium (ISM) and the mass distribution of the plasma in the Galaxy. Here, we study the interaction of an evolved SNR shock front with on a small interstellar gas cloud. Our model takes into account the hydrodynamics and the effects of the radiative losses and of the thermal conduction. We study the interplay between the radiative cooling and the thermal conduction during the cloud evolution and their effect on the mass and energy exchange between the cloud and the surrounding medium. We find that in cases dominated by the radiative losses the cloud fragments into cold, dense, and compact filaments surrounded by a hot corona which is ablated by the thermal conduction; instead, in cases dominated by the thermal conduction, the shocked cloud evaporates into the ISM in a few dynamical time-scales. In all the cases analyzed we find that the thermal conduction suppresses the hydrodynamic instabilities at the cloud boundaries.

  10. Cloud-scale ISM Structure and Star Formation in M51

    Science.gov (United States)

    Leroy, Adam K.; Schinnerer, Eva; Hughes, Annie; Kruijssen, J. M. Diederik; Meidt, Sharon; Schruba, Andreas; Sun, Jiayi; Bigiel, Frank; Aniano, Gonzalo; Blanc, Guillermo A.; Bolatto, Alberto; Chevance, Mélanie; Colombo, Dario; Gallagher, Molly; Garcia-Burillo, Santiago; Kramer, Carsten; Querejeta, Miguel; Pety, Jerome; Thompson, Todd A.; Usero, Antonio

    2017-09-01

    We compare the structure of molecular gas at 40 pc resolution to the ability of gas to form stars across the disk of the spiral galaxy M51. We break the PAWS survey into 370 pc and 1.1 kpc resolution elements, and within each we estimate the molecular gas depletion time ({τ }{Dep}{mol}), the star-formation efficiency per free-fall time ({ɛ }{ff}), and the mass-weighted cloud-scale (40 pc) properties of the molecular gas: surface density, Σ, line width, σ, and b\\equiv {{Σ }}/{σ }2\\propto {α }{vir}-1, a parameter that traces the boundedness of the gas. We show that the cloud-scale surface density appears to be a reasonable proxy for mean volume density. Applying this, we find a typical star-formation efficiency per free-fall time, {ɛ }{ff}( )˜ 0.3 % {--}0.36 % , lower than adopted in many models and found for local clouds. Furthermore, the efficiency per free-fall time anti-correlates with both Σ and σ, in some tension with turbulent star-formation models. The best predictor of the rate of star formation per unit gas mass in our analysis is b\\equiv {{Σ }}/{σ }2, tracing the strength of self-gravity, with {τ }{Dep}{mol}\\propto {b}-0.9. The sense of the correlation is that gas with stronger self-gravity (higher b) forms stars at a higher rate (low {τ }{Dep}{mol}). The different regions of the galaxy mostly overlap in {τ }{Dep}{mol} as a function of b, so that low b explains the surprisingly high {τ }{Dep}{mol} found toward the inner spiral arms found by Meidt et al. (2013).

  11. Aerosol/Cloud Measurements Using Coherent Wind Doppler Lidars

    Directory of Open Access Journals (Sweden)

    Royer Philippe

    2016-01-01

    LEOSPHERE has recently developed aerosol/cloud detection and characterization on WINDCUBE long range Coherent Wind Doppler Lidars (CWDL. These new features combine wind and backscatter intensity informations (Carrier-to-Noise Ratio CNR in order to detect (aerosol/cloud base and top, PBL height and to characterize atmospheric structures (attenuated backscatter, depolarization ratio. For each aerosol/cloud functionality the method is described, limitations are discussed and examples are given to illustrate the performances.

  12. Intensification of convective extremes driven by cloud-cloud interaction

    CERN Document Server

    Moseley, Christopher; Berg, Peter; Haerter, Jan O

    2015-01-01

    In a changing climate, a key role may be played by the response of convective-type cloud and precipitation to temperature changes. Yet, it is unclear if precipitation intensities will increase mainly due to modified thermodynamic forcing or due to stronger convective dynamics. In gradual self-organization, convective events produce highest intensities late in the day. Tracking rain cells throughout their life cycles, we find that interacting events respond strongly to changes in boundary conditions. Conversely, events without interaction remain unaffected. Increased surface temperature indeed leads to more interaction and higher precipitation extremes. However, a similar intensification occurs when leaving temperature unchanged but simply granting more time for self-organization.Our study implies that the convective field as a whole acquires a memory of past precipitation and inter-cloud dynamics, driving extremes. Our results implicate that the dynamical interaction between convective clouds must be incorpor...

  13. Numerical investigation for the effects of the vertical wind shear on the cloud droplet spectra broadening at the lateral boundary of the cumulus clouds

    Science.gov (United States)

    Wang, Yongqing; Sun, Jiming

    2014-05-01

    The vortex-structure circulation at the top of cumulus clouds can result in air entrainment at the lateral sides of them. The entrained air at the early developing stage of cumulus clouds can lead to new cloud droplet activation at their lateral sides due to its upward expansion cooling induced by the gradient force of the dynamic perturbation pressure. The vertical wind shear may strengthen such a mechanism for cloud droplet nucleation at the lateral sides of cumulus clouds. In order to investigate the impacts of the vertical wind shear on the cloud droplet spectra broadening at the lateral sides, we used the Weather Research and Forecasting (WRF) Model coupled with an aerosol-cloud interaction bin model with a high spectrum resolution (90 bins for aerosols, 160 bins for water drops) and a high spatial resolution (25m in vertical, 50m in horizontal). We run the Large Eddy Simulation (LES) case in the Tianhe supercomputer with more than 1000 CPUs. In our simulations, a new aerosol parameterization scheme have been proposed in order to investigate the secondary activation of cloud condensation nuclei (CCN). The activated CCN will not be cleaned as the current approach. CCN coming from the evaporated cloud droplets can be explicitly determined. Our results show that the vertical wind shear can enhance the cloud droplet nucleation at the leeward lateral side.

  14. Mechanisms and Model Diversity of Trade-Wind Shallow Cumulus Cloud Feedbacks: A Review

    Science.gov (United States)

    Vial, Jessica; Bony, Sandrine; Stevens, Bjorn; Vogel, Raphaela

    2017-07-01

    Shallow cumulus clouds in the trade-wind regions are at the heart of the long standing uncertainty in climate sensitivity estimates. In current climate models, cloud feedbacks are strongly influenced by cloud-base cloud amount in the trades. Therefore, understanding the key factors controlling cloudiness near cloud-base in shallow convective regimes has emerged as an important topic of investigation. We review physical understanding of these key controlling factors and discuss the value of the different approaches that have been developed so far, based on global and high-resolution model experimentations and process-oriented analyses across a range of models and for observations. The trade-wind cloud feedbacks appear to depend on two important aspects: (1) how cloudiness near cloud-base is controlled by the local interplay between turbulent, convective and radiative processes; (2) how these processes interact with their surrounding environment and are influenced by mesoscale organization. Our synthesis of studies that have explored these aspects suggests that the large diversity of model responses is related to fundamental differences in how the processes controlling trade cumulus operate in models, notably, whether they are parameterized or resolved. In models with parameterized convection, cloudiness near cloud-base is very sensitive to the vigor of convective mixing in response to changes in environmental conditions. This is in contrast with results from high-resolution models, which suggest that cloudiness near cloud-base is nearly invariant with warming and independent of large-scale environmental changes. Uncertainties are difficult to narrow using current observations, as the trade cumulus variability and its relation to large-scale environmental factors strongly depend on the time and/or spatial scales at which the mechanisms are evaluated. New opportunities for testing physical understanding of the factors controlling shallow cumulus cloud responses using

  15. Mechanisms and Model Diversity of Trade-Wind Shallow Cumulus Cloud Feedbacks: A Review

    Science.gov (United States)

    Vial, Jessica; Bony, Sandrine; Stevens, Bjorn; Vogel, Raphaela

    2017-11-01

    Shallow cumulus clouds in the trade-wind regions are at the heart of the long standing uncertainty in climate sensitivity estimates. In current climate models, cloud feedbacks are strongly influenced by cloud-base cloud amount in the trades. Therefore, understanding the key factors controlling cloudiness near cloud-base in shallow convective regimes has emerged as an important topic of investigation. We review physical understanding of these key controlling factors and discuss the value of the different approaches that have been developed so far, based on global and high-resolution model experimentations and process-oriented analyses across a range of models and for observations. The trade-wind cloud feedbacks appear to depend on two important aspects: (1) how cloudiness near cloud-base is controlled by the local interplay between turbulent, convective and radiative processes; (2) how these processes interact with their surrounding environment and are influenced by mesoscale organization. Our synthesis of studies that have explored these aspects suggests that the large diversity of model responses is related to fundamental differences in how the processes controlling trade cumulus operate in models, notably, whether they are parameterized or resolved. In models with parameterized convection, cloudiness near cloud-base is very sensitive to the vigor of convective mixing in response to changes in environmental conditions. This is in contrast with results from high-resolution models, which suggest that cloudiness near cloud-base is nearly invariant with warming and independent of large-scale environmental changes. Uncertainties are difficult to narrow using current observations, as the trade cumulus variability and its relation to large-scale environmental factors strongly depend on the time and/or spatial scales at which the mechanisms are evaluated. New opportunities for testing physical understanding of the factors controlling shallow cumulus cloud responses using

  16. A Search for Hydrodynamical Interaction Between the ISM and Radio Jets in IC4296

    Science.gov (United States)

    Mackie, Glen

    1998-01-01

    The ROSAT HRI Data set on IC 4296 has been reduced and analysed. A draft paper on the small-scale structure of x-ray emission and its relation to the radio emission has been written. Mackie left the Smithsonian Astrophysical Observatory in September 1997 and in January 1998 he joined the staff at Carter Observatory, New Zealand. Mackie is currently (May 1998) upgrading computer software at Carter to run IRAF-PROS and XSPEC x-ray software packages in order to reduce and analyze archival ROSAT PSPC data on IC 4296. The PSPC results are needed to investigate the hot gas temperature and abundance properties that will be used in conjunction with the radio jet properties to determine the hydrodynamical interaction status of IC 4296, and finalize the results of a research paper.

  17. A comprehensive numerical study of aerosol-cloud-precipitation interactions in marine stratocumulus

    Directory of Open Access Journals (Sweden)

    Y.-C. Chen

    2011-09-01

    Full Text Available Three-dimensional large-eddy simulations (LES with detailed bin-resolved microphysics are performed to explore the diurnal variation of marine stratocumulus (MSc clouds under clean and polluted conditions. The sensitivity of the aerosol-cloud-precipitation interactions to variation of sea surface temperature, free tropospheric humidity, large-scale divergence rate, and wind speed is assessed. The comprehensive set of simulations corroborates previous studies that (1 with moderate/heavy drizzle, an increase in aerosol leads to an increase in cloud thickness; and (2 with non/light drizzle, an increase in aerosol results in a thinner cloud, due to the pronounced effect on entrainment. It is shown that for higher SST, stronger large-scale divergence, drier free troposphere, or lower wind speed, the cloud thins and precipitation decreases. The sign and magnitude of the Twomey effect, droplet dispersion effect, cloud thickness effect, and cloud optical depth susceptibility to aerosol perturbations (i.e., change in cloud optical depth to change in aerosol number concentration are evaluated by LES experiments and compared with analytical formulations. The Twomey effect emerges as dominant in total cloud optical depth susceptibility to aerosol perturbations. The dispersion effect, that of aerosol perturbations on the cloud droplet size spectrum, is positive (i.e., increase in aerosol leads to spectral narrowing and accounts for 3% to 10% of the total cloud optical depth susceptibility at nighttime, with greater influence in heavier drizzling clouds. The cloud thickness effect is negative (i.e., increase in aerosol leads to thinner cloud for non/light drizzling cloud and positive for a moderate/heavy drizzling clouds; the cloud thickness effect contributes 5% to 22% of the nighttime total cloud susceptibility. Overall, the total cloud optical depth susceptibility ranges from ~0.28 to 0.53 at night; an increase in aerosol concentration enhances cloud

  18. SGP Cloud and Land Surface Interaction Campaign (CLASIC): Measurement Platforms

    Energy Technology Data Exchange (ETDEWEB)

    MA Miller; R Avissar; LK Berg; SA Edgerton; ML Fischer; TJ Jackson; B. Kustas; PJ Lamb; G McFarquhar; Q Min; B Schmid; MS Torn; DD Tuner

    2007-06-01

    The Cloud and Land Surface Interaction Campaign (CLASIC) will be conducted from June 8 to June 30, 2007, at the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site. Data will be collected using eight aircraft equipped with a variety of specialized sensors, four specially instrumented surface sites, and two prototype surface radar systems. The architecture of CLASIC includes a high-altitude surveillance aircraft and enhanced vertical thermodynamic and wind profile measurements that will characterize the synoptic scale structure of the clouds and the land surface within the ACRF SGP site. Mesoscale and microscale structures will be sampled with a variety of aircraft, surface, and radar observations. An overview of the measurement platforms that will be used during the CLASIC are described in this report. The coordination of measurements, especially as it relates to aircraft flight plans, will be discussed in the CLASIC Implementation Plan.

  19. Interactive Trunk Extraction from Forest Point Cloud

    Directory of Open Access Journals (Sweden)

    T. Mizoguchi

    2014-06-01

    Full Text Available For forest management or monitoring, it is required to constantly measure several parameters of each tree, such as height, diameter at breast height, and trunk volume. Terrestrial laser scanner has been used for this purpose instead of human workers to reduce time and cost for the measurement. In order to use point cloud captured by terrestrial laser scanner in the above applications, it is an important step to extract all trees or their trunks separately. For this purpose, we propose an interactive system in which a user can intuitively and efficiently extract each trunk by a simple editing on the distance image created from the point cloud. We demonstrate the effectiveness of our proposed system from various experiments.

  20. Cloud tracking of the Venus atmosphere with Akatsuki: High-quality wind snapshots, jets, and instabilities

    Science.gov (United States)

    Horinouchi, T.; Murakami, S.; Satoh, T.; Watanabe, S.; Kouyama, T.; Ogohara, K.; Imamura, T.; Takagi, M.; Kashimura, H.; Peralta, J.; Limaye, S. S.; Sato, T. M.; Nakamura, M.; Yamada, M.; Yamazaki, A.; Young, E. F.

    2017-09-01

    We have conducted cloud tracking using image data from Akatsuki, a Venus orbiting satellite, at multiple wavelengths. Our method provides cloud-motion vectors with unprecedented high quality. Obtained cloud top winds exhibit rich spatial and temporal variability. In the lower cloud layer, it is observed that a jet stream was formed in the equatorial region in 2016, which persisted at least over a few months. Occasionally, batropically unstable vortices are found to develop to erode the shear associated with the jet.

  1. 3-D numerical simulations of eruption clouds: Effects of the environmental wind on the turbulent mixing

    Science.gov (United States)

    Suzuki, Y. J.; Koyaguchi, T.

    2011-12-01

    During an explosive volcanic eruption, a mixture of volcanic gas and solid pyroclasts are ejected from a volcanic vent with a high temperature. As it rises, the mixture entrains ambient air owing to turbulent mixing. The entrained air expands by heating from the hot pyroclasts, and the eruption cloud (i.e., the ejected material plus the entrained air) rises as a buoyant plume. Because the plume height is principally determined by the balance between the thermal energy ejected at the vent and the work done in transporting the ejected material plus entrained air through the atmospheric stratification, it is controlled by the efficiency of turbulent mixing; as the amount of entrained air increases, the plume height decreases. In the 1-D models of eruption column (e.g., Woods, 1988), the plume height is calculated on the assumption that the mean inflow velocity across the edge of turbulent jet and/or plume is proportional to the mean vertical velocity (Morton et al., 1956). Experimental studies suggest that the proportionality constant (i.e., entrainment coefficient, k), which represents the efficiency of turbulent mixing, is about 0.10 for pure plumes when there is no wind. When an environmental wind is present, however, the interaction between a buoyant plume and the wind may enhance the entrainment of air and can significantly decrease the plume height (Bursik, 2001). In order to investigate the effects of wind on the vortical structures and the efficiency of turbulent mixing in an eruption cloud, we have carried out 3-D numerical simulations of eruption column which is ejected in a wind field. The simulation results indicate that a buoyant plume vertically rises as a "strong plume" (e.g., Bonadonna et al., 2003) when the wind velocity is low: the cloud reaches the neutral buoyancy level and overshoots until the upward momentum is exhausted. In this case, the plume height is consistent with prediction by the 1-D model with k~0.10. When the wind velocity is high, on

  2. Primary marine aerosol-cloud interactions off the coast of California

    Science.gov (United States)

    Modini, R. L.; Frossard, A. A.; Ahlm, L.; Russell, L. M.; Corrigan, C. E.; Roberts, G. C.; Hawkins, L. N.; Schroder, J. C.; Bertram, A. K.; Zhao, R.; Lee, A. K. Y.; Abbatt, J. P. D.; Lin, J.; Nenes, A.; Wang, Z.; Wonaschütz, A.; Sorooshian, A.; Noone, K. J.; Jonsson, H.; Seinfeld, J. H.; Toom-Sauntry, D.; MacDonald, A. M.; Leaitch, W. R.

    2015-05-01

    Primary marine aerosol (PMA)-cloud interactions off the coast of California were investigated using observations of marine aerosol, cloud condensation nuclei (CCN), and stratocumulus clouds during the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE) and the Stratocumulus Observations of Los-Angeles Emissions Derived Aerosol-Droplets (SOLEDAD) studies. Based on recently reported measurements of PMA size distributions, a constrained lognormal-mode-fitting procedure was devised to isolate PMA number size distributions from total aerosol size distributions and applied to E-PEACE measurements. During the 12 day E-PEACE cruise on the R/V Point Sur, PMA typically contributed less than 15% of total particle concentrations. PMA number concentrations averaged 12 cm-3 during a relatively calmer period (average wind speed 12 m/s1) lasting 8 days, and 71 cm-3 during a period of higher wind speeds (average 16 m/s1) lasting 5 days. On average, PMA contributed less than 10% of total CCN at supersaturations up to 0.9% during the calmer period; however, during the higher wind speed period, PMA comprised 5-63% of CCN (average 16-28%) at supersaturations less than 0.3%. Sea salt was measured directly in the dried residuals of cloud droplets during the SOLEDAD study. The mass fractions of sea salt in the residuals averaged 12 to 24% during three cloud events. Comparing the marine stratocumulus clouds sampled in the two campaigns, measured peak supersaturations were 0.2 ± 0.04% during E-PEACE and 0.05-0.1% during SOLEDAD. The available measurements show that cloud droplet number concentrations increased with >100 nm particles in E-PEACE but decreased in the three SOLEDAD cloud events.

  3. Interaction between main components in wind farms

    DEFF Research Database (Denmark)

    Holdyk, Andrzej; Koldby, Erik

    The purpose of the research documented in this thesis was to establish technical and scientific methods and tools for characterizing offshore wind farms’ electrical main components and their interaction in medium- and high-frequency, taking into account different electrical conditions and wind...... response analyser. The method was validated on a 300 kVA power transformer with wye-wye winding connections giving accurate results. Large disproportions between magnitudes of eigenvalues of sub-matrices of admittance matrix are introduced when one of the windings of the transformer is ungrounded....... This results in poor fitting and the entire model being inaccurate. The accuracy of small eigenvalues was improved by performing additional measurements of zero-sequence admittance elements and approximating using vector fitting and constant-transformation matrix. The robustness of the measurement device...

  4. A framework for cloud - Aerosol interaction study

    NARCIS (Netherlands)

    Sarna, K.; Russchenberg, H.W.J.

    2012-01-01

    Aerosols can indirectly influence climate either by cloud albedo or lifetime effect. In order to have better understanding of these processes it is crucial to measure detailed vertical profiles of the radiative transfer and the microphysical evolution of clouds. Best results can be achieved by using

  5. Using MODIS cloud regimes to sort diagnostic signals of aerosol-cloud-precipitation interactions

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin

    2017-05-01

    Coincident multiyear measurements of aerosol, cloud, precipitation, and radiation at near-global scales are analyzed to diagnose their apparent relationships as suggestive of interactions previously proposed based on theoretical, observational, and model constructs. Specifically, we examine whether differences in aerosol loading in separate observations go along with consistently different precipitation, cloud properties, and cloud radiative effects. Our analysis uses a cloud regime (CR) framework to dissect and sort the results. The CRs come from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor and are defined as distinct groups of cloud systems with similar covariations of cloud top pressure and cloud optical thickness. Aerosol optical depth used as proxy for aerosol loading comes from two sources, MODIS observations and the MERRA-2 reanalysis, and its variability is defined with respect to local seasonal climatologies. The choice of aerosol data set impacts our results substantially. We also find that the responses of the marine and continental component of a CR are frequently quite disparate. Overall, CRs dominated by warm clouds tend to exhibit less ambiguous signals but also have more uncertainty with regard to precipitation changes. Finally, we find weak, but occasionally systematic covariations of select meteorological indicators and aerosol, which serve as a sober reminder that ascribing changes in cloud and cloud-affected variables solely to aerosol variations is precarious.

  6. Data-ism

    CERN Document Server

    Lohr, Steve

    2015-01-01

    Coal, iron ore and oil were the fuel of the Industrial Revolution. Today's economies and governments are powered by something far less tangible: the explosive abundance of digital data.Steve Lohr, the New York Times' chief technology reporter, charts the ascent of Data-ism, the dominating philosophy of the day in which data is at the forefront of everything and decisions of all kinds are based on data analysis rather than experience and intuition. Taking us behind the scenes and introducing the DOPs (Data Oriented-People), the key personalities behind this revolution, he reveals how consuming

  7. Wind Turbine Converter Control Interaction with Complex Wind Farm Systems

    DEFF Research Database (Denmark)

    Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

    2013-01-01

    in this study. It is shown that wind farm components, such as long high-voltage alternating current cables and park transformers, can introduce significant low-frequency series resonances seen from the wind turbine terminals that can affect wind turbine control system operation and overall wind farm stability...

  8. Using the Annual Cycle to Understand Climate Model Biases in Trade-wind Clouds

    Science.gov (United States)

    Medeiros, B.; Nuijens, L.

    2014-12-01

    This study investigates the clouds of the north Atlantic trade-wind region as represented in climate models. We focus on an area near Barbados, a site with long-term cloud observations. We begin by asking whether the annual cycle of cloud cover is properly represented in models compared to satellite observations and reanalysis. The models robustly overestimate the amplitude of the annual cycle in cloud cover compared to satellite estimates, but qualitatively capture the phase of the annual cycle with the cloudiest months in the summer wet season in association with deeper convection and higher clouds. We show that the wet season biases are associated with biases in the large-scale circulation, in particular the location of the ITCZ. During the dry season, however, cloud cover is underestimated. Comparison of simulated cloud fraction with the expected cloud-controlling factors shows only weak relationships and little correspondence between the models and observation-based estimates. We infer that the cloud cover variations within the dry season are controlled at least as much by local factors as large-scale ones; these local factors are determined by parameterized physics in the climate models. Like the cloud cover, the vertical structure of the the simulated clouds varies tremendously across models. Perhaps unsurprisingly, the shortwave cloud radiative effect (SWCRE) is relatively well-captured by the models during the dry season, signaling a common compensating bias among the models and reaffirming the ''too few, too bright'' error. Conditioning on dry season and SWCRE shows that models diverge as to the cause of SWCRE variation, some having more influence from shallow cumulus cloud variation while others show more dependence on middle and upper-level clouds. These higher clouds are usually considered unimportant for the overall cloudiness and the shortwave radiation budget in the trades, but this does not appear to be the case at least for some models. Since

  9. Strong Constraints on Aerosol-Cloud Interactions from Volcanic Eruptions

    Science.gov (United States)

    Malavelle, Florent F.; Haywood, Jim M.; Jones, Andy; Gettelman, Andrew; Clarisse, Lieven; Bauduin, Sophie; Allan, Richard P.; Karset, Inger Helene H.; Kristjansson, Jon Egill; Oreopoulos, Lazaros; hide

    2017-01-01

    Aerosols have a potentially large effect on climate, particularly through their interactions with clouds, but the magnitude of this effect is highly uncertain. Large volcanic eruptions produce sulfur dioxide, which in turn produces aerosols; these eruptions thus represent a natural experiment through which to quantify aerosol-cloud interactions. Here we show that the massive 2014-2015 fissure eruption in Holuhraun, Iceland, reduced the size of liquid cloud droplets - consistent with expectations - but had no discernible effect on other cloud properties. The reduction in droplet size led to cloud brightening and global-mean radiative forcing of around minus 0.2 watts per square metre for September to October 2014. Changes in cloud amount or cloud liquid water path, however, were undetectable, indicating that these indirect effects, and cloud systems in general, are well buffered against aerosol changes. This result will reduce uncertainties in future climate projections, because we are now able to reject results from climate models with an excessive liquid-water-path response.

  10. Strong constraints on aerosol-cloud interactions from volcanic eruptions

    Science.gov (United States)

    Malavelle, Florent F.; Haywood, Jim M.; Jones, Andy; Gettelman, Andrew; Clarisse, Lieven; Bauduin, Sophie; Allan, Richard P.; Karset, Inger Helene H.; Kristjánsson, Jón Egill; Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Bellouin, Nicolas; Boucher, Olivier; Grosvenor, Daniel P.; Carslaw, Ken S.; Dhomse, Sandip; Mann, Graham W.; Schmidt, Anja; Coe, Hugh; Hartley, Margaret E.; Dalvi, Mohit; Hill, Adrian A.; Johnson, Ben T.; Johnson, Colin E.; Knight, Jeff R.; O'Connor, Fiona M.; Partridge, Daniel G.; Stier, Philip; Myhre, Gunnar; Platnick, Steven; Stephens, Graeme L.; Takahashi, Hanii; Thordarson, Thorvaldur

    2017-06-01

    Aerosols have a potentially large effect on climate, particularly through their interactions with clouds, but the magnitude of this effect is highly uncertain. Large volcanic eruptions produce sulfur dioxide, which in turn produces aerosols; these eruptions thus represent a natural experiment through which to quantify aerosol-cloud interactions. Here we show that the massive 2014-2015 fissure eruption in Holuhraun, Iceland, reduced the size of liquid cloud droplets—consistent with expectations—but had no discernible effect on other cloud properties. The reduction in droplet size led to cloud brightening and global-mean radiative forcing of around -0.2 watts per square metre for September to October 2014. Changes in cloud amount or cloud liquid water path, however, were undetectable, indicating that these indirect effects, and cloud systems in general, are well buffered against aerosol changes. This result will reduce uncertainties in future climate projections, because we are now able to reject results from climate models with an excessive liquid-water-path response.

  11. Cloud Regimes as a Tool for Systematic Study of Various Aerosol-Cloud-Precipitation Interactions

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin

    2016-01-01

    Systematic changes of clouds and precipitation are notoriously difficult to ascribe to aerosols. This presentation will showcase yet one more attempt to at least credibly detect the signal of aerosol-cloud-precipitation interactions. We surmise that the concept of cloud regimes (CRs) is appropriate to conduct such an investigation. Previous studies focused on what we call here dynamical CRs, and while we continue to adopt those too for our analysis, we have found that a different way of organizing cloud systems, namely via microphysical regimes is also promising. Our analysis relies on MODIS Collection 6 Level-3 data for clouds and aerosols, and TRMM-TMPA data for precipitation. The regimes are derived by applying clustering analysis on MODIS joint histograms, and once each grid cell is assigned a regime, aerosol and precipitation data can be spatiotemporally matched and composited by regime. The composites of various cloud and precipitation variables for high (upper quartile of distribution) and low (lower quartile) aerosol loadings can then be contrasted. We seek evidence of aerosol effects both in regimes with large fractions of deep ice-rich clouds, as well as regimes where low liquid phase clouds dominate. Signals can be seen, especially when the analysis is broken by land-ocean and when additional filters are applied, but there are of course caveats which will be discussed.

  12. Interaction of cosmic rays with cold clouds in galactic haloes

    Science.gov (United States)

    Wiener, Joshua; Oh, S. Peng; Zweibel, Ellen G.

    2017-05-01

    We investigate the effects of cosmic ray (CR) dynamics on cold, dense clouds embedded in a hot, tenuous galactic halo. If the magnetic field does not increase too much inside the cloud, the local reduction in Alfvén speed imposes a bottleneck on CRs streaming out from the star-forming galactic disc. The bottleneck flattens the upstream CR gradient in the hot gas, implying that multiphase structure could have global effects on CR-driven winds. A large CR pressure gradient can also develop on the outward-facing edge of the cloud. This pressure gradient has two independent effects. The CRs push the cloud upwards, imparting it with momentum. On smaller scales, the CRs pressurize cold gas in the fronts, reducing its density, consistent with the low densities of cold gas inferred in recent Cosmic Origins Spectrograph (COS) observations of local L* galaxies. They also heat the material at the cloud edge, broadening the cloud-halo interface and causing an observable change in interface ionic abundances. Due to the much weaker temperature dependence of CR heating relative to thermal-conductive heating, CR mediated fronts have a higher ratio of low-to-high ions compared to conduction fronts, in better agreement with observations. We investigate these effects separately using 1D simulations and analytic techniques.

  13. Cloud-radiation interactions and their parameterization in climate models

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-11-01

    This report contains papers from the International Workshop on Cloud-Radiation Interactions and Their Parameterization in Climate Models met on 18--20 October 1993 in Camp Springs, Maryland, USA. It was organized by the Joint Working Group on Clouds and Radiation of the International Association of Meteorology and Atmospheric Sciences. Recommendations were grouped into three broad areas: (1) general circulation models (GCMs), (2) satellite studies, and (3) process studies. Each of the panels developed recommendations on the. themes of the workshop. Explicitly or implicitly, each panel independently recommended observations of basic cloud microphysical properties (water content, phase, size) on the scales resolved by GCMs. Such observations are necessary to validate cloud parameterizations in GCMs, to use satellite data to infer radiative forcing in the atmosphere and at the earth`s surface, and to refine the process models which are used to develop advanced cloud parameterizations.

  14. Roles of Wind Shear at Different Vertical Levels, Part I: Cloud System Organization and Properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qian; Fan, Jiwen; Hagos, Samson M.; Gustafson, William I.; Berg, Larry K.

    2015-07-07

    Understanding of critical processes that contribute to the organization of mesoscale convective systems is important for accurate weather forecast and climate prediction. In this study, we investigate the effects of wind shear at different vertical levels on the organization and properties of cloud systems using the Weather Research & Forecasting (WRF) model with a spectral-bin microphysical scheme. The sensitivity experiments are performed by increasing wind shear at the lower (0-5 km), middle (5-10 km), upper (> 10 km) and the entire troposphere, respectively, based on a control run for a mesoscale convective system (MCS) with weak wind shear. We find that increasing wind shear at the both lower and middle vertical levels reduces the domain-accumulated precipitation and the occurrence of heavy rain, while increasing wind shear at the upper levels changes little on precipitation. Although increasing wind shear at the lower-levels is favorable for a more organized quasi-line system which leads to enlarged updraft core area, and enhanced updraft velocities and vertical mass fluxes, the precipitation is still reduced by 18.6% compared with the control run due to stronger rain evaporation induced by the low-level wind shear. Strong wind shear in the middle levels only produces a strong super-cell over a narrow area, leading to 67.3% reduction of precipitation over the domain. By increasing wind shear at the upper levels only, the organization of the convection is not changed much, but the increased cloudiness at the upper-levels leads to stronger surface cooling and then stabilizes the atmosphere and weakens the convection. When strong wind shear exists over the entire vertical profile, a deep dry layer (2-9 km) is produced and convection is severely suppressed. There are fewer very-high (cloud top height (CTH) > 15 km) and very-deep (cloud thickness > 15 km) clouds, and the precipitation is only about 11.8% of the control run. The changes in cloud microphysical

  15. Turbulence Simulation of Laboratory Wind-Wave Interaction in High Winds and Upscaling to Ocean Conditions

    Science.gov (United States)

    2016-12-22

    by gale force and stronger winds. This project seeks to reconcile laboratory and field measurements of wind-wave interaction and surface drag in...December 2016 Award Number: N00014-12-10184 Turbulence Simulation of Laboratory Wind-Wave Interaction in High Winds and Upscaling to Ocean...modulational properties appears warranted. Our simulations did not account for: long wave-short wave interactions which may impact strongly on

  16. Green Bank Telescope Detection of HI Clouds in the Fermi Bubble Wind

    Science.gov (United States)

    Lockman, Felix; Di Teodoro, Enrico M.; McClure-Griffiths, Naomi M.

    2018-01-01

    We used the Robert C. Byrd Green Bank Telescope to map HI 21cm emission in two large regions around the Galactic Center in a search for HI clouds that might be entrained in the nuclear wind that created the Fermi bubbles. In a ~160 square degree region at |b|>4 deg. and |long|nuclear wind. Rapidly moving clouds are found as far as 1.5 kpc from the center; there are no detectable asymmetries in the cloud populations above and below the Galactic Center. The cloud kinematics is modeled as a population with an outflow velocity of 330 km/s that fills a cone with an opening angle ~140 degrees. The total mass in the clouds is ~10^6 solar masses and we estimate cloud lifetimes to be between 2 and 8 Myr, implying a cold gas mass-loss rate of about 0.1 solar masses per year into the nuclear wind.The Green Bank Telescope is a facility of the National Science Foundation, operated under a cooperative agreement by Associated Universities, Inc.

  17. The Cloud and Land Surface Interaction Campaign (CLASIC)

    Science.gov (United States)

    Miller, M. A.

    2008-05-01

    The consequences of increasing greenhouse gas concentrations on the Earth's climate system are evaluated using Global Climate Models, which must accurately simulate the complex array of mechanisms and feedbacks in the climate system and predict how they will operate in the future. A significant challenge for these models is the representation of cumulus convection, which is an important component of the water and energy budget of the planet and plays a key role in the hydrologic cycle. The role of cumulus convection in the water budget is particularly important in semi-arid regions and in regions with significant agricultural interests. In situations where the synoptic scale forcing is weak and the surface is sufficiently moist, continental cumulus convection may be strongly modulated by land surface conditions, while at the same time influencing the land surface itself through rain-induced changes in soil moisture and through its impact on photosynthesis. Many of the properties of the land surface that likely influence the development and evolution of cumulus convection can be altered by human activities such as urban development and agriculture. The Cloud and Land Surface Interaction Campaign (CLASIC) was conducted in the Southern Great Plains of the United States during June 2007. A principal goal of the experiment was to examine these interactions when shallow convection was the dominant cloud type across the SGP domain. The experiment was lead by the Department of Energy's (DOE's) Atmospheric Radiation Measurement (ARM) Program and held at the ARM Southern Great Plains (SGP) Climate Research Facility. Additional support was provided by the National Aeronautics and Space Administration and the United States Department of Agriculture. A multiple scale observation approach was used during CLASIC. Large scale forcing was quantified using enhanced radiosonde observations within the SGP site in conjunction with the National Oceanic and Atmospheric Administration

  18. Long-term Behaviour Of Venus Winds At Cloud Level From Virtis/vex Observations

    Science.gov (United States)

    Hueso, Ricardo; Peralta, J.; Sánchez-Lavega, A.; Pérez-Hoyos, S.; Piccioni, G.; Drossart, P.

    2009-09-01

    The Venus Express (VEX) mission has been in orbit to Venus for more than three years now. The VIRTIS instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. Images in the ultraviolet range are used to study the upper cloud at 66 km while images in the infrared (1.74 μm) map the opacity of the lower cloud deck at 48 km. Here we present an analysis of the overall dynamics of Venus’ atmosphere at both levels using observations that cover a large fraction of the VIRTIS dataset. We will present our latest results concerning the zonal winds, the overall stability in the lower cloud deck motions and the variability in the upper cloud. Meridional winds are also observed in the upper and lower cloud in the UV and IR images obtained with VIRTIS. While the upper clouds present a net meridional motion consistent with the upper branch of a Hadley cell the lower cloud present more irregular, variable and less intense motions in the meridional direction. Acknowledgements This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07. RH acknowledges a "Ramón y Cajal” contract from MEC.

  19. Cloud level winds from UV and IR images obtained by VMC onboard Venus Express

    Science.gov (United States)

    Khatuntsev, Igor; Patsaeva, Marina; Titov, Dmitri; Ignatiev, Nikolay; Turin, Alexander; Bertaux, Jean-Loup

    2017-04-01

    During eight years Venus Monitoring Camera (VMC) [1] onboard the Venus Express orbiter has observed the upper cloud layer of Venus. The largest set of images was obtained in the UV (365 nm), visible (513 nm) and two infrared channels - 965 nm and 1010 nm. The UV dayside images were used to study the atmospheric circulation at the Venus cloud tops [2], [3]. Mean zonal and meridional profiles of winds and their variability were derived from cloud tracking of UV images. In low latitudes the mean retrograde zonal wind at the cloud top (67±2 km) is about 95 m/s with a maximum of about 102 m/s at 40-50°S. Poleward from 50°S the zonal wind quickly fades out with latitude. The mean poleward meridional wind slowly increases from zero value at the equator to about 10 m/s at 50°S. Poleward from this latitude, the absolute value of the meridional component monotonically decreases to zero at the pole. The VMC observations suggest clear diurnal signature in the wind field. They also indicate a long term trend for the zonal wind speed at low latitudes to increase from 85 m/s in the beginning of the mission to 110 m/s by the middle of 2012. The trend was explained by influence of the surface topography on the zonal flow [4]. Cloud features tracking in the IR images provided information about winds in the middle cloud deck (55±4 km). In the low and middle latitudes (5-65°S) the IR mean retrograde zonal velocity is about 68-70 m/s. In contrast to poleward flow at the cloud tops, equatorward motions dominate in the middle cloud with maximum speed of 5.8±1.2 m/s at latitude 15°S. The meridional speed slowly decreases to 0 at 65-70°S. At low latitudes the zonal and meridional speed demonstrate long term variations. Following [4] we explain the observed long term trend of zonal and meridional components by the influence of surface topography of highland region Aphrodite Terra on dynamic processes in the middle cloud deck through gravity waves. Acknowledgements: I.V. Khatuntsev

  20. Studying Wind Energy/Bird Interactions: A Guidance Document

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R. [California Energy Commission (US); Morrison, M. [California State Univ., Sacramento, CA (US); Sinclair, K. [Dept. of Energy/National Renewable Energy Lab. (US); Strickland, D. [WEST, Inc. (US)

    1999-12-01

    This guidance document is a product of the Avian Subcommittee of the National Wind Coordinating Committee (NWCC). The NWCC was formed to better understand and promote responsible, credible, and comparable avian/wind energy interaction studies. Bird mortality is a concern and wind power is a potential clean and green source of electricity, making study of wind energy/bird interactions essential. This document provides an overview for regulators and stakeholders concerned with wind energy/bird interactions, as well as a more technical discussion of the basic concepts and tools for studying such interactions.

  1. Global impact of 3D cloud-radiation interactions

    Science.gov (United States)

    Schäfer, Sophia; Hogan, Robin; Fielding, Mark; Chiu, Christine

    2017-04-01

    Clouds have a decisive impact on the Earth's radiation budget and on the temperature of the atmosphere and surface. However, in global weather and climate models, cloud-radiation interaction is treated in only the vertical dimension using several non-realistic assumptions, which contributes to the large uncertainty on the climatic role of clouds. We provide a first systematic investigation into the impact of horizontal radiative transport for both shortwave and longwave radiation on a global, long-term scale. For this purpose, we have developed and validated the SPARTACUS radiation scheme, a method for including three-dimensional radiative transfer effects approximately in a one-dimensional radiation calculation that is numerically efficient enough for global calculations, allowing us to conduct 1D and quasi-3D radiation calculations for a year of global of ERA-Interim re-analysis atmospheric data and compare the results of various radiation treatments. SPARTACUS includes the effects of cloud internal inhomogeneity, horizontal in-region transport and the spatial distribution of in-cloud radiative fluxes.The impact of varying three-dimensional cloud geometry can be described by one parameter, the effective cloud scale, which has a characteristic value for each cloud type. We find that both the 3D effects of cloud-side transport and of horizontal in-cloud radiative transport in the shortwave are significant. Overall, 3D cloud effects warm the Earth by about 4 W m -2 , with warming effects in both the shortwave and the longwave. The dominant 3D cloud effect is the previously rarely investigated in-region horizontal transfer effect in the shortwave, which significantly decreases cloud reflectance and warms the Earth system by 5 W m -2 , partly counteracted by the cooling effect of shortwave 3D cloud-side transport. Longwave heating and cooling at various heights is strengthened by up to 0.2 K d ^{-1} and -0.3 K d ^{-1} respectively. These 3D effects, neglected by

  2. The Interaction of Cosmic Rays with Diffuse Clouds

    Science.gov (United States)

    Everett, John E.; Zweibel, Ellen G.

    2011-10-01

    We study the change in cosmic-ray pressure, the change in cosmic-ray density, and the level of cosmic-ray-induced heating via Alfvén-wave damping when cosmic rays move from a hot ionized plasma to a cool cloud embedded in that plasma. The general analysis method outlined here can apply to diffuse clouds in either the ionized interstellar medium or in galactic winds. We introduce a general-purpose model of cosmic-ray diffusion building upon the hydrodynamic approximation for cosmic rays (from McKenzie & Völk and Breitschwerdt and collaborators). Our improved method self-consistently derives the cosmic-ray flux and diffusivity under the assumption that the streaming instability is the dominant mechanism for setting the cosmic-ray flux and diffusion. We find that, as expected, cosmic rays do not couple to gas within cool clouds (cosmic rays exert no forces inside of cool clouds), that the cosmic-ray density does not increase within clouds (it may decrease slightly in general, and decrease by an order of magnitude in some cases), and that cosmic-ray heating (via Alfvén-wave damping and not collisional effects as for ~10 MeV cosmic rays) is only important under the conditions of relatively strong (10 μG) magnetic fields or high cosmic-ray pressure (~10-11 erg cm-3).

  3. Using a Venus Atmosphere Model to Investigate Variations in Cloud-level Winds and Temperatures

    Science.gov (United States)

    Parish, Helen; Mitchell, Jonathan

    2017-10-01

    We have developed a new Venus Middle atmosphere Model (VMM), which simulates the atmosphere from just below the cloud deck to around 100 km altitude, with the aim of focusing on the dynamics at cloud levels and above. We take this approach as the circulation and dynamics between the ground and cloud altitudes are not well known. Wind velocities below ~40 km altitude cannot be observed remotely and there are only a few in-situ wind profiles from entry probes on the Venera and Pioneer Venus missions, which are limited in spatial and temporal coverage. However, in the atmosphere at cloud altitudes significant information can be obtained on the circulation and dynamics of Venus' atmosphere and many more observations are available, including measurements from Venus Express and Akatsuki. Preliminary results from the VMM with a simplified radiation scheme have been validated by comparison with Pioneer Venus and Venus Express measurements and show reasonable agreement with the observations. Values of parameters near the lower boundary which are not well measured can be inferred by comparison with values at higher altitudes. We use sensitivity experiments to determine the most important processes involved in shaping the wind and temperature structure at cloud altitudes. We compare the results of simulations with measurements from Pioneer Venus and Venera probes and from the Venus Express and Akatsuki missions

  4. Multiple Lightning Discharges in Wind Turbines Associated with Nearby Cloud-to-Ground Lightning

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Cummins, Kenneth L.; Madsen, Søren Find

    2015-01-01

    -triggering video cameras were correlated with data from the U.S. National Lighting Detection Network. In all five events, the correlation showed that a cloud-to-ground (CG) lightning stroke with high peak current struck the ground within 10 km of the affected turbines at the time of the currents in the wind...

  5. Venus winds at cloud level from VIRTIS during the Venus Express mission

    Science.gov (United States)

    Hueso, Ricardo; Peralta, Javier; Sánchez-Lavega, Agustín.; Pérez-Hoyos, Santiago; Piccioni, Giuseppe; Drossart, Pierre

    2010-05-01

    The Venus Express (VEX) mission has been in orbit to Venus for almost four years now. The VIRTIS instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. Images in the ultraviolet range are used to study the upper cloud at 66 km while images in the infrared (1.74 μm) map the opacity of the lower cloud deck at 48 km. Here we present our latest results on the analysis of the global atmospheric dynamics at these cloud levels using a large selection over the full VIRTIS dataset. We will show the atmospheric zonal superrotation at these levels and the mean meridional motions. The zonal winds are very stable in the lower cloud at mid-latitudes to the tropics while it shows different signatures of variability in the upper cloud where solar tide effects are manifest in the data. While the upper clouds present a net meridional motion consistent with the upper branch of a Hadley cell the lower cloud present almost null global meridional motions at all latitudes but with particular features traveling both northwards and southwards in a turbulent manner depending on the cloud morphology on the observations. A particular important atmospheric feature is the South Polar vortex which might be influencing the structure of the zonal winds in the lower cloud at latitudes from the vortex location up to 55°S. Acknowledgements This work has been funded by the Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464-07.

  6. “Section to Point” Correction Method for Wind Power Forecasting Based on Cloud Theory

    Directory of Open Access Journals (Sweden)

    Dunnan Liu

    2015-01-01

    Full Text Available As an intermittent energy, wind power has the characteristics of randomness and uncontrollability. It is of great significance to improve the accuracy of wind power forecasting. Currently, most models for wind power forecasting are based on wind speed forecasting. However, it is stuck in a dilemma called “garbage in, garbage out,” which means it is difficult to improve the forecasting accuracy without improving the accuracy of input data such as the wind speed. In this paper, a new model based on cloud theory is proposed. It establishes a more accurate relational model between the wind power and wind speed, which has lots of catastrophe points. Then, combined with the trend during adjacent time and the laws of historical data, the forecasting value will be corrected by the theory of “section to point” correction. It significantly improves the stability of forecasting accuracy and reduces significant forecasting errors at some particular points. At last, by analyzing the data of generation power and historical wind speed in Inner Mongolia, China, it is proved that the proposed method can effectively improve the accuracy of wind speed forecasting.

  7. On the overtaking interaction of typical shock waves in the solar wind flow

    Science.gov (United States)

    Grib, S. A.

    2010-01-01

    The interaction of traveling fast solar shock waves with other fast shock waves generated previously is considered in terms of magnetohydrodynamics for various solar wind parameters. The shocks are not piston ones and move freely in the flow. The magnetic structure in the interplanetary magnetic field emerging after the shock interaction is shown to correspond to the well-known magnetic configuration commonly observed on spacecraft or the classical Hundhausen R model. A head-on collision of solar shock waves with the boundary of a magnetic cloud is considered. It is pointed out that a slow shockwave refracted into the magnetic cloud can appear at an oblique collision of the shock with the cloud boundary. The results clarify our understanding of the available spacecraft data.

  8. Meridional and Zonal winds at Venus' atmosphere from Cloud-tracking, Doppler techniques and comparison with modelling

    Science.gov (United States)

    Machado, P.; Widemann, T.; Peralta, J.; Gonçalves, R.; Gilli, G.; Silva, M.

    2017-09-01

    We present final results of the meridional wind in both Venus' hemispheres and spatial and temporal variability of the zonal wind, based on coordinated observations at Venus cloud-tops with two complementary techniques: Ground-based Doppler velocimetry and cloud-tracked winds using VEx/VIRTIS-M. We also present final results based on observations of Venus' bottom of the cloud deck at nightside, carried out with NICS/TNG.The observational results will be compared with the ground-to-thermosphere 3D model developed at LMD (Paris).

  9. 915-MHz Wind Profiler for Cloud Forecasting at Brookhaven National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Bartholomew, M. J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Giangrande, S. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-03-01

    When considering the amount of shortwave radiation incident on a photovoltaic solar array and, therefore, the amount and stability of the energy output from the system, clouds represent the greatest source of short-term (i.e., scale of minutes to hours) variability through scattering and reflection of incoming solar radiation. Providing estimates of this short-term variability is important for determining and regulating the output from large solar arrays as they connect with the larger power infrastructure. In support of the installation of a 37-MW solar array on the grounds of Brookhaven National Laboratory (BNL), a study of the impacts of clouds on the output of the solar array has been undertaken. The study emphasis is on predicting the change in surface solar radiation resulting from the observed/forecast cloud field on a 5-minute time scale. At these time scales, advection of cloud elements over the solar array is of particular importance. As part of the BNL Aerosol Life Cycle Intensive Operational Period (IOP), a 915-MHz Radar Wind Profiler (RWP) was deployed to determine the profile of low-level horizontal winds and the depth of the planetary boundary layer. The initial deployment mission of the 915-MHz RWP for cloud forecasting has been expanded the deployment to provide horizontal wind measurements for estimating and constraining cloud advection speeds. A secondary focus is on the observation of dynamics and microphysics of precipitation during cold season/winter storms on Long Island. In total, the profiler was deployed at BNL for 1 year from May 2011 through May 2012.

  10. 915-Mhz Wind Profiler for Cloud Forecasting at Brookhaven National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, M. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Bartholomew, M. J. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Giangrande, S. [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2016-03-01

    When considering the amount of shortwave radiation incident on a photovoltaic solar array and, therefore, the amount and stability of the energy output from the system, clouds represent the greatest source of short-term (i.e., scale of minutes to hours) variability through scattering and reflection of incoming solar radiation. Providing estimates of this short-term variability is important for determining and regulating the output from large solar arrays as they connect with the larger power infrastructure. In support of the installation of a 37-MW solar array on the grounds of Brookhaven National Laboratory (BNL), a study of the impacts of clouds on the output of the solar array has been undertaken. The study emphasis is on predicting the change in surface solar radiation resulting from the observed/forecast cloud field on a 5-minute time scale. At these time scales, advection of cloud elements over the solar array is of particular importance. As part of the BNL Aerosol Life Cycle Intensive Operational Period (IOP), a 915-MHz Radar Wind Profiler (RWP) was deployed to determine the profile of low-level horizontal winds and the depth of the planetary boundary layer. The initial deployment mission of the 915-MHz RWP for cloud forecasting has been expanded the deployment to provide horizontal wind measurements for estimating and constraining cloud advection speeds. A secondary focus is on the observation of dynamics and microphysics of precipitation during cold season/winter storms on Long Island. In total, the profiler was deployed at BNL for 1 year from May 2011 through May 2012.

  11. Intercomparison of aerosol-cloud-precipitation interactions in stratiform orographic mixed-phase clouds

    Directory of Open Access Journals (Sweden)

    A. Muhlbauer

    2010-09-01

    Full Text Available Anthropogenic aerosols serve as a source of both cloud condensation nuclei (CCN and ice nuclei (IN and affect microphysical properties of clouds. Increasing aerosol number concentrations is hypothesized to retard the cloud droplet coalescence and the riming in mixed-phase clouds, thereby decreasing orographic precipitation.

    This study presents results from a model intercomparison of 2-D simulations of aerosol-cloud-precipitation interactions in stratiform orographic mixed-phase clouds. The sensitivity of orographic precipitation to changes in the aerosol number concentrations is analysed and compared for various dynamical and thermodynamical situations. Furthermore, the sensitivities of microphysical processes such as coalescence, aggregation, riming and diffusional growth to changes in the aerosol number concentrations are evaluated and compared.

    The participating numerical models are the model from the Consortium for Small-Scale Modeling (COSMO with bulk microphysics, the Weather Research and Forecasting (WRF model with bin microphysics and the University of Wisconsin modeling system (UWNMS with a spectral ice habit prediction microphysics scheme. All models are operated on a cloud-resolving scale with 2 km horizontal grid spacing.

    The results of the model intercomparison suggest that the sensitivity of orographic precipitation to aerosol modifications varies greatly from case to case and from model to model. Neither a precipitation decrease nor a precipitation increase is found robustly in all simulations. Qualitative robust results can only be found for a subset of the simulations but even then quantitative agreement is scarce. Estimates of the aerosol effect on orographic precipitation are found to range from −19% to 0% depending on the simulated case and the model.

    Similarly, riming is shown to decrease in some cases and models whereas it increases in others, which implies that a decrease in riming

  12. Akatsuki (space based cloud-tracking) and TNG/HARPS-N (ground based Doppler velocimetry) coordinated wind measurements of cloud top Venus' atmosphere

    Science.gov (United States)

    Gonçalves, R.; Machado, P.; Peralta, J.; Lee, Y. J.; Widemann, T.; Harutyunyan, A.

    2017-09-01

    HARPS-N spectrograph was used for the first time to study the atmosphere's dynamics of a solar system body. We present zonal and meridional winds profiles of Venus' cloud top atmosphere, from coordinated observations using TNG/HARPS-N (Doppler velocimetry) and space-based Akatsuki (cloud tracking). The HARPS-N spectrograph provided unprecedented high quality spectra at Venus atmosphere, allowing us to retrieve wind velocities with an unmatched precision and spatial and temporal accuracy. The data will contribute to better constrain both zonal and meridional wind flow and detect and characterize mesoscale atmospheric waves on Venus' atmosphere.

  13. Mobile devices and computing cloud resources allocation for interactive applications

    Directory of Open Access Journals (Sweden)

    Krawczyk Henryk

    2017-06-01

    Full Text Available Using mobile devices such as smartphones or iPads for various interactive applications is currently very common. In the case of complex applications, e.g. chess games, the capabilities of these devices are insufficient to run the application in real time. One of the solutions is to use cloud computing. However, there is an optimization problem of mobile device and cloud resources allocation. An iterative heuristic algorithm for application distribution is proposed. The algorithm minimizes the energy cost of application execution with constrained execution time.

  14. Cloud and Wind Variability in Saturn's Equatorial Jet prior to the Cassini orbital tour

    Science.gov (United States)

    Sánchez-Lavega, A.; Pérez-Hoyos, S.; Hueso, R.; Rojas, J. F.; French, R. G.

    2004-11-01

    We use ground-based observations (going back to 1876), Pioneer-11 data (1979), Voyager 1 and 2 encounter images in 1980 and 1981, and HST 1990-2004 images, to study the changes that occurred in the vertical cloud structure and morphology and motions, in Saturn's Equatorial Region (approximately the band between latitudes 40 deg North and South). We compare ``calm periods" with ``stormy periods" i. e. those that occur during the development of the phenomenon known as the ``Great White Spots." We discuss different interpretations of the mechanisms that can be involved in the observed changes: vertical wind shears, waves, storm - mean flow interaction and changes in atmospheric angular momentum. Acknowledgements: This work was supported by the Spanish MCYT AYA 2003-03216. SPH acknowledges a PhD fellowship from the Spanish MECD and RH a post-doc fellowship from Gobierno Vasco. RGF was supported in part by NASA's Planetary Geology and Geophysics Program NAG5-10197 and STSCI Grant GO-08660.01A.

  15. Introducing tree interactions in wind damage simulations

    NARCIS (Netherlands)

    Schelhaas, M.J.; Kramer, K.; Peltola, H.; Werf, van der D.C.; Wijdeven, S.M.J.

    2007-01-01

    Wind throw is an important risk factor in forest management in North-western Europe. In recent years, mechanistic models have been developed to estimate critical wind speeds needed to break or uproot the average tree of a forest stand. Based on these models, we developed a wind damage module for the

  16. Layered Atlantic Smoke Interactions with Clouds (LASIC) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Zuidema, P [University of Miami; Chiu, C [University of Reading; Fairall, CW [NOAA - Environmental Technology Laboratory; Ghan, SJ [Pacific Northwest National Laboratory; Kollias, P [Stony Brook University; McFarguhar, GM; Mechem, DB [University of Kansas; Romps, DM [Lawrence Berkeley National Laboratory; Wong, H; Yuter, SE [North Carolina State University; Alvarado, MJ [Atmospheric and Environmental Research, Inc.; DeSzoeke, SP; Feingold, G [NOAA - Earth System Research Laboratory; Haywood, JM; Lewis, ER [Brookhaven National Laboratory; McComiskey, A [National Oceanic and Atmospheric Administration; Redemann, J [NASA - Ames Research Center; Turner, DD [National Oceanic and Atmospheric Administration; Wood, R [University of Washington; Zhu, P [Florida International University

    2015-12-01

    Southern Africa is the world’s largest emitter of biomass-burning (BB) aerosols. Their westward transport over the remote southeast Atlantic Ocean colocates some of the largest atmospheric loadings of absorbing aerosol with the least examined of the Earth’s major subtropical stratocumulus decks. Global aerosol model results highlight that the largest positive top-of-atmosphere forcing in the world occurs in the southeast Atlantic, but this region exhibits large differences in magnitude and sign between reputable models, in part because of high variability in the underlying model cloud distributions. Many uncertainties contribute to the highly variable model radiation fields: the aging of shortwave-absorbing aerosol during transport, how much of the aerosol mixes into the cloudy boundary layer, and how the low clouds adjust to smoke-radiation and smoke-cloud interactions. In addition, the ability of the BB aerosol to absorb shortwave radiation is known to vary seasonally as the fuel type on land changes.

  17. Cloud County Community College Wind Energy Technology Project and Renewable Energy Center of Excellence

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Bruce [Cloud County Community College, Concordia, KS (United States)

    2016-02-26

    Cloud County Community College's (CCCC) Wind Energy Technology (WET) program is a leader in the renewable energy movement across Kansas and the USA. The field of renewable energy is a growing industry which continues to experience high demand for career opportunities. This CCCC/DOE project entailed two phases: 1) the installation of two Northwind 100 wind turbines, and 2) the continued development of the WET program curriculum, including enhancement of the CCCC Blade Repair Certificate program. This report provides a technical account of the total work performed, and is a comprehensive description of the results achieved.

  18. Electron Velocity Distribution Function in Magnetic Clouds in the Solar Wind

    Science.gov (United States)

    Nieves-Chinchil, Teresa; Vinas, Adolfo F.; Bale, Stuart D.

    2006-01-01

    We present a study of the kinetic properties of the electron velocity distribution functions within magnetic clouds, since they are the dominant thermal component. The study is based on high time resolution data from the GSFC WIND/SWE electron spectrometer and the Berkeley 3DP electron plasma instruments. Recent studies on magnetic clouds have shown observational evidence of anti-correlation between the total electron density and electron temperature, which suggest a polytrope law P(sub e) = alpha(Nu(sub e) (sup gamma)) for electrons with the constant gamma approximates 0.5 < 1. This anti-correlation and small polytropic gamma-values is interpreted in the context of the presence of highly non-Maxwellian electron distributions (i.e. non-thermal) within magnetic clouds. These works suggested that the non-thermal electrons can contribute as much as 50% of the total electron pressure within magnetic clouds. We have revisited some of the magnetic cloud events previously studied and attempted to quantify the nature of the non-thermal electrons by modeling the electron velocity distribution function using a kappa distribution function to characterize the kinetic non-thermal effects. If non-thermal tail effects are the source for the anti-correlation between the moment electron temperature and density and if the kappa distribution is a reasonable representative model of non-thermal effects, then the electron velocity distribution within magnetic clouds should show indication for small K-values when gamma < 1.

  19. Squeezed between shells: The fate of the Lupus I molecular cloud

    Science.gov (United States)

    Gaczkowski, Benjamin; Preibisch, Thomas; Stanke, Thomas

    2015-08-01

    Today molecular cloud formation is attributed to collisions of large-scale flows in the ISM. Such flows can be driven by stellar feedback processes and supernovae. The numerous massive stars in the three sub-groups of the Sco-Cen OB-association created a huge system of expanding loop-like H I structures around each of the sub-groups. The Lupus I molecular cloud is situated in the middle between the Upper-Scorpius (USco) and the Upper-Centaurus-Lupus (UCL) sub-groups. At this location the expanding USco H I shell interacts with a bubble driven by the winds of the remaining B-stars of UCL. With a distance of 150 pc Lupus I represents the nearest example where we can study how such a collision process forms and influences new dense clouds in the ISM. We present LABOCA continuum sub-mm observations of Lupus I, complemented by Herschel and Planck data from which we constructed column density and temperature maps to characterize the cloud in a multi-wavelength approach. All maps revealed that the cloud can be divided into two distinct regions. The northern part that has on average lower densities and higher temperatures as well as no active star formation and the center-south part with dozens of pre-stellar and protostellar cores where density and temperature reach their maximum and minimum, respectively. The column density PDFs from the Herschel data show double-peaked profiles for all parts of the cloud. In those parts with active star formation also a power-law tail is found. With LABOCA the PDFs follow the denser parts of the cloud showing good agreement with those from Herschel for the second lognormal component and the power-law tail. The distribution of the 15 cores we found with LABOCA confirms that only the center-south part of Lupus I is actively forming stars whereas the north is quiescent. We argue that the main driving agents in the formation process of Lupus I are the advancing USco H I shell in whose edge the cloud is most likely embedded colliding with

  20. Interacting bubble clouds and their sonochemical production

    CERN Document Server

    Stricker, Laura; Rivas, David Fernandez; Lohse, Detlef

    2013-01-01

    Acoustically driven air pockets trapped in artificial crevices on a sur- face can emit bubbles which organize in (interacting) bubble clusters. With increasing driving power Fernandez Rivas et al. [Angew. Chem. Int. Ed., 2010] observed three different behaviors: clusters close to the very pits out of which they had been created, clusters pointing toward each other, and merging clusters. The latter behavior is highly undesired for technological purposes as it is associated with a reduction of the radical production and an enhancement of the erosion of the reactor walls. The dependence on the control parameters such as the distance of the pits and the conditions for cluster-merging are examined. The underlying mechanism, governed by the secondary Bjerknes forces, turns out to be strongly influenced by the nonlinearity of the bubble oscillations and not directly by the number of nucleated bubbles. The Bjerknes forces are found to dampen the bubble oscillations, thus reducing the radical production. Therefore, th...

  1. Wind/wave interactions in the surf zone

    OpenAIRE

    King, Daniel Martin.

    1994-01-01

    Wind/wave interactions in the surf zone are studied using a wave tank and environmental wind tunnel. The wind simulation is achieved over a relatively short fetch using accelerated growth techniques at a scale of roughly 1:100. Waves are scaled at approximately 1:50, and consequently there is some scaling mis-match between the wind and wave simulations. Results show that wind has a significant effect on the breaking of the waves. Both breaker location and breaker type are shown to be affe...

  2. Interactions in Massive Colliding Wind Binaries

    Directory of Open Access Journals (Sweden)

    Michael F. Corcoran

    2012-03-01

    Full Text Available There are observational difficulties determining dynamical masses of binary star components in the upper HR diagram both due to the scarcity of massive binary systems and spectral and photometric contamination produced by the strong wind outflows in these systems. We discuss how variable X-ray emission in these systems produced by wind-wind collisions in massive binaries can be used to constrain the system parameters, with application to two important massive binaries, Eta Carinae and WR 140.

  3. A State-of-the-Art Experimental Laboratory for Cloud and Cloud-Aerosol Interaction Research

    Science.gov (United States)

    Fremaux, Charles M.; Bushnell, Dennis M.

    2011-01-01

    The state of the art for predicting climate changes due to increasing greenhouse gasses in the atmosphere with high accuracy is problematic. Confidence intervals on current long-term predictions (on the order of 100 years) are so large that the ability to make informed decisions with regard to optimum strategies for mitigating both the causes of climate change and its effects is in doubt. There is ample evidence in the literature that large sources of uncertainty in current climate models are various aerosol effects. One approach to furthering discovery as well as modeling, and verification and validation (V&V) for cloud-aerosol interactions is use of a large "cloud chamber" in a complimentary role to in-situ and remote sensing measurement approaches. Reproducing all of the complex interactions is not feasible, but it is suggested that the physics of certain key processes can be established in a laboratory setting so that relevant fluid-dynamic and cloud-aerosol phenomena can be experimentally simulated and studied in a controlled environment. This report presents a high-level argument for significantly improved laboratory capability, and is meant to serve as a starting point for stimulating discussion within the climate science and other interested communities.

  4. Cloud, Aerosol, and Complex Terrain Interactions (CACTI) Preliminary Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Varble, Adam [Univ. of Utah, Salt Lake City, UT (United States); Nesbitt, Steve [Univ. of Illinois, Urbana-Champaign, IL (United States); Salio, Paola [Univ. of Buenos Aires (Argentina); Zipser, Edward [Univ. of Utah, Salt Lake City, UT (United States); van den Heever, Susan [Colorado State Univ., Fort Collins, CO (United States); McFarquhar, Greg [Univ. of Illinois, Urbana-Champaign, IL (United States); Kollias, Pavlos [Stony Brook Univ., NY (United States); Kreidenweis, Sonia [Colorado State Univ., Fort Collins, CO (United States); DeMott, Paul [Colorado State Univ., Fort Collins, CO (United States); Jensen, Michael [Brookhaven National Lab. (BNL), Upton, NY (United States); Houze, Jr., Robert [Univ. of Washington, Seattle, WA (United States); Rasmussen, Kristen [Colorado State Univ., Fort Collins, CO (United States); Leung, Ruby [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Romps, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gochis, David [National Center for Atmospheric Research, Boulder, CO (United States); Avila, Eldo [National Univ. of Cordoba (Argentina); Williams, Christopher [Univ. of Colorado, Boulder, CO (United States); National Center for Atmospheric Research, Boulder, CO (United States)

    2017-02-01

    General circulation models and downscaled regional models exhibit persistent biases in deep convective initiation location and timing, cloud top height, stratiform area and precipitation fraction, and anvil coverage. Despite important impacts on the distribution of atmospheric heating, moistening, and momentum, nearly all climate models fail to represent convective organization, while system evolution is not represented at all. Improving representation of convective systems in models requires characterization of their predictability as a function of environmental conditions, and this characterization depends on observing many cases of convective initiation, non-initiation, organization, and non-organization. The Cloud, Aerosol, and Complex Terrain Interactions (CACTI) experiment in the Sierras de Córdoba mountain range of north-central Argentina is designed to improve understanding of cloud life cycle and organization in relation to environmental conditions so that cumulus, microphysics, and aerosol parameterizations in multi-scale models can be improved. The Sierras de Córdoba range has a high frequency of orographic boundary-layer clouds, many reaching congestus depths, many initiating into deep convection, and some organizing into mesoscale systems uniquely observable from a single fixed site. Some systems even grow upscale to become among the deepest, largest, and longest-lived in the world. These systems likely contribute to an observed regional trend of increasing extreme rainfall, and poor prediction of them likely contributes to a warm, dry bias in climate models downstream of the Sierras de Córdoba range in a key agricultural region. Many environmental factors influence the convective lifecycle in this region including orographic, low-level jet, and frontal circulations, surface fluxes, synoptic vertical motions influenced by the Andes, cloud detrainment, and aerosol properties. Local and long-range transport of smoke resulting from biomass burning as

  5. SWAN: a Service for Interactive Analysis in the Cloud

    CERN Document Server

    Piparo, Danilo; Mato, Pere; Mascetti, Luca; Moscicki, Jakub; Lamanna, Massimo

    2016-01-01

    SWAN (Service for Web based ANalysis) is a platform to perform interactive data analysis in the cloud. SWAN allows users to write and run their data analyses with only a web browser, leveraging on the widely-adopted Jupyter notebook interface. The user code, executions and data live entirely in the cloud. SWAN makes it easier to produce and share results and scientific code, access scientific software, produce tutorials and demonstrations as well as preserve analyses. Furthermore, it is also a powerful tool for non-scientific data analytics. This paper describes how a pilot of the SWAN service was implemented and deployed at CERN. Its backend combines state-of-the-art software technologies with a set of existing IT services such as user authentication, virtual computing infrastructure, mass storage, file synchronisation and sharing, specialised clusters and batch systems. The added value of this combination of services is discussed, with special focus on the opportunities offered by the CERNBox service and it...

  6. Wide Field Coverage for Juno (WFCJ): Jupiter's 2D Wind Field and Cloud Structure

    Science.gov (United States)

    Wong, Michael

    2017-08-01

    Juno will take novel measurements in the jovian system during HST Cycles 23, 24, and 25. This proposal supports Juno's neutral atmospheric investigation, which includes measurements with an IR imager/spectrometer (JIRAM) and the Microwave Radiometer (MWR). Both will achieve high spatial resolution as the orbiter swoops past Jupiter, in between the radiation belts and the cloud tops. But instrument fields of view are small compared to the planet, so HST observations would provide valuable context and complementary information.We propose to measure Jupiter's 2D wind field, as well as UV/optical cloud colors (and their evolution). We will measure winds using sets of global maps that cover two of Juno's perijove passes, characterizing the time-varying dynamics of waves, jets, vortices, and storms. The remaining perijove passes will be covered by snapshot (1-orbit) visits, sufficient to characterize feature morphology along each Juno track at high resolution. These observations will give crucial context for MWR observations and enable more precise retrievals from MWR data. Earth-based support is particularly important for Juno, due to its highly eccentric orbit and specialized instrumentation. WFC3/UVIS imaging can play an important role in the effort, since no other facility can obtain precise 2D wind fields and UV/optical photometry at high spatial resolution. Without the HST component of this campaign, key dynamical constraints will be missing.

  7. Flow interaction of diffuser augmented wind turbines

    Science.gov (United States)

    Göltenbott, U.; Ohya, Y.; Yoshida, S.; Jamieson, P.

    2016-09-01

    Up-scaling of wind turbines has been a major trend in order to reduce the cost of energy generation from the wind. Recent studies however show that for a given technology, the cost always rises with upscaling, notably due to the increased mass of the system. To reach capacities beyond 10 MW, multi-rotor systems (MRS) have promising advantages. On the other hand, diffuser augmented wind turbines (DAWTs) can significantly increase the performance of the rotor. Up to now, diffuser augmentation has only been applied to single small wind turbines. In the present research, DAWTs are used in a multi-rotor system. In wind tunnel experiments, the aerodynamics of two and three DAWTs, spaced in close vicinity in the same plane normal to a uniform flow, have been analysed. Power increases of up to 5% and 9% for the two and three rotor configurations are respectively achieved in comparison to a stand-alone turbine. The physical dynamics of the flows are analysed on the basis of the results obtained with a stand-alone turbine.

  8. Conjectures Concerning Planetary Deuterium Enrichment from Solar Wind or Galactic Clouds Driven by Planetary Magnetic Fields

    Science.gov (United States)

    Arias, F. J.

    2017-09-01

    In this poster, it is conjectured (and theoretically discussed) the possibility of planetary deuterium enrichment contribution in the past driven by planetary magnetic fields and external sources as solar winds or galactic clouds. The mechanism is interesting because: 1) is in clear contrast with current mechanism where planets and bodies are enriched with deuterium by preferential escape of ordinary hydrogen. 2) is linking deuterium enrichment with body magnetic fields, and then observed deuterium enrichment can be a hint that in the past there was magnetic activity in the body 3) open the possibility that geological records can be find with abrupt increase of deuterium and then the possible transit of the solar system crossing galactic clouds.

  9. Interactions between exoplanets and the winds of young stars

    Directory of Open Access Journals (Sweden)

    Vidotto A. A.

    2014-01-01

    Full Text Available The topology of the magnetic field of young stars is important not only for the investigation of magnetospheric accretion, but also responsible in shaping the large-scale structure of stellar winds, which are crucial for regulating the rotation evolution of stars. Because winds of young stars are believed to have enhanced mass-loss rates compared to those of cool, main-sequence stars, the interaction of winds with newborn exoplanets might affect the early evolution of planetary systems. This interaction can also give rise to observational signatures which could be used as a way to detect young planets, while simultaneously probing for the presence of their still elusive magnetic fields. Here, we investigate the interaction between winds of young stars and hypothetical planets. For that, we model the stellar winds by means of 3D numerical magnetohydrodynamic simulations. Although these models adopt simplified topologies of the stellar magnetic field (dipolar fields that are misaligned with the rotation axis of the star, we show that asymmetric field topologies can lead to an enhancement of the stellar wind power, resulting not only in an enhancement of angular momentum losses, but also intensifying and rotationally modulating the wind interactions with exoplanets.

  10. AXISYMMETRIC SIMULATIONS OF HOT JUPITER–STELLAR WIND HYDRODYNAMIC INTERACTION

    Energy Technology Data Exchange (ETDEWEB)

    Christie, Duncan; Arras, Phil; Li, Zhi-Yun [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)

    2016-03-20

    Gas giant exoplanets orbiting at close distances to the parent star are subjected to large radiation and stellar wind fluxes. In this paper, hydrodynamic simulations of the planetary upper atmosphere and its interaction with the stellar wind are carried out to understand the possible flow regimes and how they affect the Lyα transmission spectrum. Following Tremblin and Chiang, charge exchange reactions are included to explore the role of energetic atoms as compared to thermal particles. In order to understand the role of the tail as compared to the leading edge of the planetary gas, the simulations were carried out under axisymmetry, and photoionization and stellar wind electron impact ionization reactions were included to limit the extent of the neutrals away from the planet. By varying the planetary gas temperature, two regimes are found. At high temperature, a supersonic planetary wind is found, which is turned around by the stellar wind and forms a tail behind the planet. At lower temperatures, the planetary wind is shut off when the stellar wind penetrates inside where the sonic point would have been. In this regime mass is lost by viscous interaction at the boundary between planetary and stellar wind gases. Absorption by cold hydrogen atoms is large near the planetary surface, and decreases away from the planet as expected. The hot hydrogen absorption is in an annulus and typically dominated by the tail, at large impact parameter, rather than by the thin leading edge of the mixing layer near the substellar point.

  11. Radar Wind Profiler for Cloud Forecasting at Brookhaven National Laboratory (BNL) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, M. P. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Giangrande, S. E. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Bartholomew, M. J. [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2016-04-01

    The Radar Wind Profiler for Cloud Forecasting at Brookhaven National Laboratory (BNL) [http://www.arm.gov/campaigns/osc2013rwpcf] campaign was scheduled to take place from 15 July 2013 through 15 July 2015 (or until shipped for the next U.S. Department of Energy Atmospheric Radiation Measurement [ARM] Climate Research Facility first Mobile Facility [AMF1] deployment). The campaign involved the deployment of the AMF1 Scintec 915 MHz Radar Wind Profiler (RWP) at BNL, in conjunction with several other ARM, BNL and National Weather Service (NWS) instruments. The two main scientific foci of the campaign were: 1) To provide profiles of the horizontal wind to be used to test and validate short-term cloud advection forecasts for solar-energy applications and 2) to provide vertical profiling capabilities for the study of dynamics (i.e., vertical velocity) and hydrometeors in winter storms. This campaign was a serendipitous opportunity that arose following the deployment of the RWP at the Two-Column Aerosol Project (TCAP) campaign in Cape Cod, Massachusetts and restriction from participation in the Green Ocean Amazon 2014/15 (GoAmazon 2014/15) campaign due to radio-frequency allocation restriction for international deployments. The RWP arrived at BNL in the fall of 2013, but deployment was delayed until fall of 2014 as work/safety planning and site preparation were completed. The RWP further encountered multiple electrical failures, which eventually required several shipments of instrument power supplies and the final amplifier to the vendor to complete repairs. Data collection began in late January 2015. The operational modes of the RWP were changed such that in addition to collecting traditional profiles of the horizontal wind, a vertically pointing mode was also included for the purpose of precipitation sensing and estimation of vertical velocities. The RWP operated well until the end of the campaign in July 2015 and collected observations for more than 20 precipitation

  12. Response Timescales and Multiple Equilibria in Boundary-Layer Cloud-Aerosol Interaction

    Science.gov (United States)

    Bretherton, C. S.; Berner, A.; Wood, R.

    2012-12-01

    Large-eddy simulations (LES) of subtropical stratocumulus-topped boundary layers coupled to an interactive aerosol model are run for multiday periods to examine their coupled equilibria and adjustment timescales. The LES includes two-moment Morrison microphysics, interactive radiation, and Razzak-Ghan cloud droplet activation from a single log-normal size distribution of hygroscopic aerosol with prognosed total aerosol mass and number. The aerosol evolves due to surface and entrainment sources, dry coalescence, precipitation sinks coupled to the Morrison microphysics due to autoconversion and accretion of cloud droplets (and a source due to raindrop evaporation), and cloud and rain scavenging of interstitial aerosol. Simulations are initialized with an idealized southeast Pacific stratocumulus sounding based on observations during VOCALS REx and forced with specified SST, mean subsidence, geostrophic wind, and free-tropospheric aerosol concentration. The surface aerosol source is based on the Clarke parameterization for the dependence of sea-salt number concentration on wind speed. Both surface and free-tropospheric aerosol are assumed to quickly grow to a specified size due to a surface DMS source. The goal is to explore the adjustment timescales and long-term equilibria produced by this model, to compare with studies such as Wood et al. (2012) that postulate that remote marine boundary layer aerosol concentrations are controlled as much by the precipitation sink as the surface and entrainment sources. We show that the coupled cloud-aerosol model supports rapid transitions from a solid, high aerosol, stratocumulus-capped state to a cumulus-like state reminisniscent of pockets of open cells as the liquid water path rises above a threshold supporting sufficient precipitation. The system can support multiple long-term equilibria for the same boundary forcing, or slow oscillations between a collapsed POC-like state and a deepening, thickening stratocumulus

  13. Astrospheres and Solar-like Stellar Winds

    Directory of Open Access Journals (Sweden)

    Wood Brian E.

    2004-07-01

    Full Text Available Stellar analogs for the solar wind have proven to be frustratingly difficult to detect directly. However, these stellar winds can be studied indirectly by observing the interaction regions carved out by the collisions between these winds and the interstellar medium (ISM. These interaction regions are called "astrospheres", analogous to the "heliosphere" surrounding the Sun. The heliosphere and astrospheres contain a population of hydrogen heated by charge exchange processes that can produce enough H I Ly alpha absorption to be detectable in UV spectra of nearby stars from the Hubble Space Telescope (HST. The amount of astrospheric absorption is a diagnostic for the strength of the stellar wind, so these observations have provided the first measurements of solar-like stellar winds. Results from these stellar wind studies and their implications for our understanding of the solar wind are reviewed here. Of particular interest are results concerning the past history of the solar wind and its impact on planetary atmospheres.

  14. Simultaneous observations of aerosol-cloud-albedo interactions with three stacked unmanned aerial vehicles.

    Science.gov (United States)

    Roberts, G C; Ramana, M V; Corrigan, C; Kim, D; Ramanathan, V

    2008-05-27

    Aerosol impacts on climate change are still poorly understood, in part, because the few observations and methods for detecting their effects are not well established. For the first time, the enhancement in cloud albedo is directly measured on a cloud-by-cloud basis and linked to increasing aerosol concentrations by using multiple autonomous unmanned aerial vehicles to simultaneously observe the cloud microphysics, vertical aerosol distribution, and associated solar radiative fluxes. In the presence of long-range transport of dust and anthropogenic pollution, the trade cumuli have higher droplet concentrations and are on average brighter. Our observations suggest a higher sensitivity of radiative forcing by trade cumuli to increases in cloud droplet concentrations than previously reported owing to a constrained droplet radius such that increases in droplet concentrations also increase cloud liquid water content. This aerosol-cloud forcing efficiency is as much as -60 W m(-2) per 100% percent cloud fraction for a doubling of droplet concentrations and associated increase of liquid water content. Finally, we develop a strategy for detecting aerosol-cloud interactions based on a nondimensional scaling analysis that relates the contribution of single clouds to albedo measurements and illustrates the significance of characterizing cloud morphology in resolving radiometric measurements. This study demonstrates that aerosol-cloud-albedo interactions can be directly observed by simultaneous observations below, in, and above the clouds.

  15. Role of clouds, aerosols, and aerosol-cloud interaction in 20th century simulations with GISS ModelE2

    Science.gov (United States)

    Nazarenko, L.; Rind, D. H.; Bauer, S.; Del Genio, A. D.

    2015-12-01

    Simulations of aerosols, clouds and their interaction contribute to the major source of uncertainty in predicting the changing Earth's energy and in estimating future climate. Anthropogenic contribution of aerosols affects the properties of clouds through aerosol indirect effects. Three different versions of NASA GISS global climate model are presented for simulation of the twentieth century climate change. All versions have fully interactive tracers of aerosols and chemistry in both the troposphere and stratosphere. All chemical species are simulated prognostically consistent with atmospheric physics in the model and the emissions of short-lived precursors [Shindell et al., 2006]. One version does not include the aerosol indirect effect on clouds. The other two versions include a parameterization of the interactive first indirect aerosol effect on clouds following Menon et al. [2010]. One of these two models has the Multiconfiguration Aerosol Tracker of Mixing state (MATRIX) that permits detailed treatment of aerosol mixing state, size, and aerosol-cloud activation. The main purpose of this study is evaluation of aerosol-clouds interactions and feedbacks, as well as cloud and aerosol radiative forcings, for the twentieth century climate under different assumptions and parameterizations for aerosol, clouds and their interactions in the climate models. The change of global surface air temperature based on linear trend ranges from +0.8°C to +1.2°C between 1850 and 2012. Water cloud optical thickness increases with increasing temperature in all versions with the largest increase in models with interactive indirect effect of aerosols on clouds, which leads to the total (shortwave and longwave) cloud radiative cooling trend at the top of the atmosphere. Menon, S., D. Koch, G. Beig, S. Sahu, J. Fasullo, and D. Orlikowski (2010), Black carbon aerosols and the third polar ice cap, Atmos. Chem. Phys., 10,4559-4571, doi:10.5194/acp-10-4559-2010. Shindell, D., G. Faluvegi

  16. Solar wind stream interaction regions throughout the heliosphere

    Science.gov (United States)

    Richardson, Ian G.

    2018-01-01

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

  17. Interaction of a neutral cloud moving through a magnetized plasma

    Science.gov (United States)

    Goertz, C. K.; Lu, G.

    1990-01-01

    Current collection by outgassing probes in motion relative to a magnetized plasma may be significantly affected by plasma processes that cause electron heating and cross field transport. Simulations of a neutral gas cloud moving across a static magnetic field are discussed. The authors treat a low-Beta plasma and use a 2-1/2 D electrostatic code linked with the authors' Plasma and Neutral Interaction Code (PANIC). This study emphasizes the understanding of the interface between the neutral gas cloud and the surrounding plasma where electrons are heated and can diffuse across field lines. When ionization or charge exchange collisions occur a sheath-like structure is formed at the surface of the neutral gas. In that region the crossfield component of the electric field causes the electron to E times B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating. The thermal electron current is significantly enhanced due to this heating.

  18. Flow-blade interaction in a Vertical Axis Wind Turbine

    Science.gov (United States)

    Dominguez, Roberto; Piedra, Saul; Ramos, Eduardo

    2014-11-01

    We present an analysis of the interaction between an incoming wind and three airfoils symmetrically located, and free to rotate around a common axis. The geometrical configuration considered is a two dimensional model of Vertical Axis Wind Turbine. The model is based in the conservation equations of the fluid coupled with the Newton-Lagrange equations for the interaction with the airfoils. The presence of the rigid body in the fluid is simulated using immersed boundary conditions. The interaction of the wind with the airfoil located further upstream generates a force on the airfoil and vortices that are swept downstream and collide with the other airfoils. This effect generates a complex interplay of dynamical forces whose resultant is a torque that sets the system in motion. We describe the flow around the airfoils and examine the efficiency of the system as a function of geometric variables. Our conclusions are potentially useful for the design of VAWT's.

  19. Chandrayaan-1 results on the solar wind ion - regolith interaction

    Science.gov (United States)

    Barabash, Stas

    Recently several missions (Kaguya, Chandrayaan-1, IBEX) revealed for the first time the complexity of the solar wind ions interaction with the lunar regolith. In this review we focus on the observations performed by the Chandrayaan-1 mission at the Moon but similar interaction processes take place on all airless bodies covered by regolith. Contrary to early assumptions the solar wind ions are not fully absorbed by the regolith but experience strong (10-20% of the impinging flux) backscattering. Only hydrogen was firmly identified. Helium for the helium enriched solar wind was detected only tentatively. The charge - state of the backscattered particles is mainly neutral. The fraction of H (+) varies strongly with the impinging solar wind velocity and constitutes 0.01 - 10% of the total backscattered flux. No H (-) ions were detected. The spectrum of the backscattered hydrogen is best-fitted by a Maxwellian distribution with a temperature of 40 - 160 eV linearly proportional to the solar wind velocity. The spectrum of the backscattered protons is also Maxwellian although shifted to a velocity some what smaller than the solar wind velocity. The scattering function of the neutrals is close to isotropic at large impinging angles (small solar zenith angles) and becomes backward peaked at shallow impinging angles. The scattering function and energy spectra of the backscatters indicate that the solar wind protons experience multiple collisions with surfaces of individual grain when traveling in the inter-grain space. Why the reflection efficiency is so high in this case is a puzzle. The solar wind also causes sputtering of elements composing the regolith minerals. Only sputtered oxygen was identified although at levels lower than expected. Chandrayaan-1 results on the solar wind ion - regolith interaction still remain to be explained. The orbital measurements should be complemented by measurements from landers revealing the “ground true”. Further studies of the

  20. Subsynchronous Torsional Interaction of Wind Farms with FSIG Wind Turbines Connected to LCC-HVDC Lines

    Directory of Open Access Journals (Sweden)

    Benfeng Gao

    2017-09-01

    Full Text Available High-voltage direct current (HVDC lines with line-commutated converter (LCC are being increasingly employed to transmit bulk wind power over long distance. However, this may cause the sub-synchronous torsional interaction (SSTI between the wind farms and the LCC-HVDC system. The SSTI characteristics of wind farms with fixed-speed induction generator (FSIG wind turbines connected to LCC-HVDC are investigated in this paper. To simplify the calculations, a modular modeling method is proposed for building the small-signal mathematical model of the investigated system. Small-signal analysis, participation factor analysis, and impact of dominant factors analysis are then applied to investigate the SSTI characteristics under different operating conditions. Three oscillation modes associated with the SSTI are identified in the entire system through small-signal and participation factor analysis, comprising two torsional modes and an electromechanical mode. Impact of dominant factors analysis shows that the system becomes less stable as the wind farm capacity grows and the distance between FSIG wind farm and the rectifier station increases. Moreover, the above analysis suggests that wind farms with FSIG connected to LCC-HVDC lines may not cause unstable SSTI. The electromagnetic transient simulations based on PSCAD/EMTDC (Power Systems Computer-Aided Design/Electromagnetic Transients including DC verify these results.

  1. Assessing the role of local air-sea interaction over the South Asia region in simulating the Indian Summer Monsoon (ISM) using the new earth system model RegCM-ES

    Science.gov (United States)

    Di Sante, Fabio; Coppola, Erika; Farneti, Riccardo; Giorgi, Filippo

    2017-04-01

    The South Asia climate is dominated by the monsoon precipitation that divides the climate in two different seasons, the wet and dry seasons, and it influences the lives of billions of peoples. The Indian Summer Monsoon (ISM) has different temporal and spatial scales of variability and it is mainly driven by strong air sea interactions. The monsoon interannual variability (IAV) and the intraseasonal variability (ISV) of daily rainfall are the two most important scale of analysis of this phenomenon. In this work, the Regional Earth System Model (RegCM-ES) (Sitz et al, 2016) is used to simulate the South Asia climate. Several model settings are experimented to assess the sensitivity of the monsoon system like for example two different cumulous convection schemes (Tidtke, 1989 and Emanuel, 1991), two different lateral boundary conditions in the regional ocean model (NOAA/Geophysical 5 Fluid Dynamics Laboratory MOM run, Danabasoglu et al 2014; and ORAP reanalysis, Zuo et Al 2015) and two different hydrological models (Cetemps Hydrological Model, Coppola et al, 2007; Max-Planck's HD model, Hagemann and Dümenil, 1998) for a total of 5 coupled and uncoupled simulations all covering the period from 1979 to 2008. One of the main results of the analysis of the mini RegCM-ES ensemble shows that a better representation of the IAV and of the ENSO-monsoon relationship is present in the coupled simulations. Moreover a source of monsoon predictability has been found in the one-year-lag correlation between JJAS India precipitation and ENSO, this is only evident in the coupled system where the one-year-lagged correlation coefficient between the Niño-3.4 and the ISM rainfall is much higher respect to the uncoupled one and similar to values observed between the observations and the Niño-3.4. For the subseasonal time scale, RegCM-ES shows better performance compared to the standalone version of RegCM4 (Giorgi et al 2012), in reproducing "active" and "break" spells that characterize

  2. EDITORIAL: Aerosol cloud interactions—a challenge for measurements and modeling at the cutting edge of cloud climate interactions

    Science.gov (United States)

    Spichtinger, Peter; Cziczo, Daniel J.

    2008-04-01

    Research in aerosol properties and cloud characteristics have historically been considered two separate disciplines within the field of atmospheric science. As such, it has been uncommon for a single researcher, or even research group, to have considerable expertise in both subject areas. The recent attention paid to global climate change has shown that clouds can have a considerable effect on the Earth's climate and that one of the most uncertain aspects in their formation, persistence, and ultimate dissipation is the role played by aerosols. This highlights the need for researchers in both disciplines to interact more closely than they have in the past. This is the vision behind this focus issue of Environmental Research Letters. Certain interactions between aerosols and clouds are relatively well studied and understood. For example, it is known that an increase in the aerosol concentration will increase the number of droplets in warm clouds, decrease their average size, reduce the rate of precipitation, and extend the lifetime. Other effects are not as well known. For example, persistent ice super-saturated conditions are observed in the upper troposphere that appear to exceed our understanding of the conditions required for cirrus cloud formation. Further, the interplay of dynamics versus effects purely attributed to aerosols remains highly uncertain. The purpose of this focus issue is to consider the current state of knowledge of aerosol/cloud interactions, to define the contemporary uncertainties, and to outline research foci as we strive to better understand the Earth's climate system. This focus issue brings together laboratory experiments, field data, and model studies. The authors address issues associated with warm liquid water, cold ice, and intermediate temperature mixed-phase clouds. The topics include the uncertainty associated with the effect of black carbon and organics, aerosol types of anthropogenic interest, on droplet and ice formation. Phases

  3. A numerical study of wind turbine-boundary layer interactions in a large offshore wind farm

    Science.gov (United States)

    Gupta, Tanvi; Baidya Roy, Somnath

    2017-04-01

    Large offshore wind farm installations are rapidly increasing all over the world driven by the availability of strong, consistent winds and the unavailability of appropriate land sites. This study quantitatively explores the interaction between wind turbines and the marine atmospheric boundary layer and its impacts on power generation in a hypothetical large offshore wind farm off the western coast of India in the Arabian Sea. The simulations are conducted using the mesoscale model WRF equipped with a wind turbine parameterization, which approximates a wind turbine as a sink of resolved kinetic energy and a source of turbulent kinetic energy. In this study, the WRF parameterization is modified to include the effects of density variations. The simulations are conducted over a 300 km x 300 km domain discretised with an 1 km grid with 10000 turbines placed in the centre. Wind turbines extract atmospheric kinetic energy and convert it into electricity. The extraction of kinetic energy from the atmospheric flow leads to two major phenomena: (1) momentum deficit in the wakes that reduce energy availability for downwind turbines and (2) enhanced vertical convergence to partly replenish the momentum deficit. Results show a 200% increase in vertical momentum convergence, with 95% of that coming from sub-grid turbulent eddies. However, the enhanced momentum convergence offsets only a small part of the momentum deficit. Consequently, there is a net reduction of almost 60% in power production for turbines in the interior of the farm compared to the turbines at the leading edge. These results suggest that a numerical model like WRF that accounts for both the momentum deficit and enhanced momentum convergence effects may provide better estimates of wind power generation than traditional wind speed density or wake model approaches.

  4. The Character of the Solar Wind, Surface Interactions, and Water

    Science.gov (United States)

    Farrell, William M.

    2011-01-01

    We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system.

  5. Nearshore regional behavior of lightning interaction with wind turbines

    Directory of Open Access Journals (Sweden)

    Gilbert A. Malinga

    2016-01-01

    Full Text Available The severity of lightning strikes on offshore wind turbines built along coastal and nearshore regions can pose safety concerns that are often overlooked. In this research study the behavior of electrical discharges for wind turbines that might be located in the nearshore regions along the East Coast of China and Sea of Japan were characterized using a physics-based model that accounted for a total of eleven different geometrical and lightning parameters. Utilizing the electrical potential field predicted using this model it was then possible to estimate the frequency of lightning strikes and the distribution of electrical loads utilizing established semi-empirical relationships and available data. The total number of annual lightning strikes on an offshore wind turbine was found to vary with hub elevation, extent of cloud cover, season and geographical location. The annual lightning strike rate on a wind turbine along the nearshore region on the Sea of Japan during the winter season was shown to be moderately larger compared to the lightning strike frequency on a turbine structure on the East Coast of China. Short duration electrical discharges, represented using marginal probability functions, were found to vary with season and geographical location, exhibiting trends consistent with the distribution of the electrical peak current. It was demonstrated that electrical discharges of moderately long duration typically occur in the winter months on the East Coast of China and the summer season along the Sea of Japan. In contrast, severe electrical discharges are typical of summer thunderstorms on the East Coast of China and winter frontal storm systems along the West Coast of Japan. The electrical charge and specific energy dissipated during lightning discharges on an offshore wind turbine was found to vary stochastically, with severe electrical discharges corresponding to large electrical currents of long duration.

  6. Cloud Service for Interactive Simulation of Interregional Trade

    Directory of Open Access Journals (Sweden)

    A. S. Velichko

    2016-01-01

    Full Text Available The paper describes a mathematical model of trade flows between the territories of a region or a country in a transport network having one or more different types of marine or ground transportation. We use the approach of modeling complex communication systems to determine the most probable values of flows in case of incomplete information about the system. Transport costs between the territories are modeled within the framework of the gravity model. The payment for transportation depends on the distance between regions, the distance is estimated as the shortest way length in a given transport network or geographical distance. The mathematical formulation of the problem belongs to the class of convex mathematical programming problems and assumes the numerical solution of nonlinear optimization problem with linear constraints. Based on the model, the software is implemented as a cloud service on heterogeneous computing architectures: the simulation module is made on a highperformance server platform, management and visualization modules are produced with IACPaaS cloud platform. Communication between the platforms is established via asynchronous http-queries. For information exchange between the modules the declarative model with JSON format is developed and implemented for the objects considered in the mathematical model which are products, areas and communications. Visualization module allows to present graphically the original and the resulting matrix data and to modify the input parameters of the model interactively. The paper demonstrates the use of software for the simulation of inter-regional freight traffic of the Russian Far East region based on input data provided by open statistics sources.

  7. Winding number order in the Haldane model with interactions

    Science.gov (United States)

    Alba, E.; Pachos, J. K.; García-Ripoll, J. J.

    2016-03-01

    We study the Haldane model with nearest-neighbor interactions. This model is physically motivated by the associated implementation with ultracold atoms. We show that the topological phase of the interacting model can be characterized by a physically observable winding number. The robustness of this number extends well beyond the topological insulator phase towards attractive and repulsive interactions that are comparable to the kinetic energy scale of the model. We identify and characterize the relevant phases of the model as a function of the interaction strength.

  8. Interaction of the solar wind with comets: a Rosetta perspective.

    Science.gov (United States)

    Glassmeier, Karl-Heinz

    2017-07-13

    The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov-Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring--beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the 'singing' of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Authors.

  9. Interaction of the solar wind with comets: a Rosetta perspective

    Science.gov (United States)

    Glassmeier, Karl-Heinz

    2017-05-01

    The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov-Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring-beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the `singing' of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction. This article is part of the themed issue 'Cometary science after Rosetta'.

  10. Interaction of relativistic short proton bunches with space charge limited electron clouds

    Directory of Open Access Journals (Sweden)

    F. B. Petrov

    2014-12-01

    Full Text Available The electron cloud buildup and interaction with a train of relativistic, short proton bunches is studied using particle-in-cell codes. The simulation models describe the electron generation at the beam pipe wall as well as the wakefield behind the bunches. The study focuses on the space charge limited (saturated cloud profile between the bunches and on the incoherent tune spread caused by the interaction of the saturated cloud with individual bunches. Analytical expressions describing the pinch of a saturated electron cloud are derived and compared to simulation results.

  11. Study of Aerosol/Cloud/Radiation Interactions over the ARM SGP Site

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, C; Chin, S

    2006-03-14

    While considerable advances in the understanding of atmospheric processes and feedbacks in the climate system have led to a better representation of these mechanisms in general circulation models (GCMs), the greatest uncertainty in predictability of future climate arises from clouds and their interactions with radiation. To explore this uncertainty, cloud resolving model has been evolved as one of the main tools for understanding and testing cloud feedback processes in climate models, whereas the indirect effects of aerosols are closely linked with cloud feedback processes. In this study we incorporated an existing parameterization of cloud drop concentration (Chuang et al., 2002a) together with aerosol prediction from a global chemistry/aerosol model (IMPACT) (Rotman et al., 2004; Chuang et al., 2002b; Chuang et al., 2005) into LLNL cloud resolving model (Chin, 1994; Chin et al., 1995; Chin and Wilhelmson, 1998) to investigate the effects of aerosols on cloud/precipitation properties and the resulting radiation fields over the Southern Great Plains.

  12. The structure and origin of magnetic clouds in the solar wind

    Directory of Open Access Journals (Sweden)

    V. Bothmer

    1998-01-01

    Full Text Available Plasma and magnetic field data from the Helios 1/2 spacecraft have been used to investigate the structure of magnetic clouds (MCs in the inner heliosphere. 46 MCs were identified in the Helios data for the period 1974–1981 between 0.3 and 1 AU. 85% of the MCs were associated with fast-forward interplanetary shock waves, supporting the close association between MCs and SMEs (solar mass ejections. Seven MCs were identified as direct consequences of Helios-directed SMEs, and the passage of MCs agreed with that of interplanetary plasma clouds (IPCs identified as white-light brightness enhancements in the Helios photometer data. The total (plasma and magnetic field pressure in MCs was higher and the plasma-β lower than in the surrounding solar wind. Minimum variance analysis (MVA showed that MCs can best be described as large-scale quasi-cylindrical magnetic flux tubes. The axes of the flux tubes usually had a small inclination to the ecliptic plane, with their azimuthal direction close to the east-west direction. The large-scale flux tube model for MCs was validated by the analysis of multi-spacecraft observations. MCs were observed over a range of up to ~60° in solar longitude in the ecliptic having the same magnetic configuration. The Helios observations further showed that over-expansion is a common feature of MCs. From a combined study of Helios, Voyager and IMP data we found that the radial diameter of MCs increases between 0.3 and 4.2 AU proportional to the distance, R, from the Sun as R0.8 (R in AU. The density decrease inside MCs was found to be proportional to R–2.4, thus being stronger compared to the average solar wind. Four different magnetic configurations, as expected from the flux-tube concept, for MCs have been observed in situ by the Helios probes. MCs with left- and right-handed magnetic helicity occurred with about equal frequencies during 1974–1981, but surprisingly, the majority (74% of the MCs had a south to north (SN

  13. The structure and origin of magnetic clouds in the solar wind

    Directory of Open Access Journals (Sweden)

    V. Bothmer

    Full Text Available Plasma and magnetic field data from the Helios 1/2 spacecraft have been used to investigate the structure of magnetic clouds (MCs in the inner heliosphere. 46 MCs were identified in the Helios data for the period 1974–1981 between 0.3 and 1 AU. 85% of the MCs were associated with fast-forward interplanetary shock waves, supporting the close association between MCs and SMEs (solar mass ejections. Seven MCs were identified as direct consequences of Helios-directed SMEs, and the passage of MCs agreed with that of interplanetary plasma clouds (IPCs identified as white-light brightness enhancements in the Helios photometer data. The total (plasma and magnetic field pressure in MCs was higher and the plasma-β lower than in the surrounding solar wind. Minimum variance analysis (MVA showed that MCs can best be described as large-scale quasi-cylindrical magnetic flux tubes. The axes of the flux tubes usually had a small inclination to the ecliptic plane, with their azimuthal direction close to the east-west direction. The large-scale flux tube model for MCs was validated by the analysis of multi-spacecraft observations. MCs were observed over a range of up to ~60° in solar longitude in the ecliptic having the same magnetic configuration. The Helios observations further showed that over-expansion is a common feature of MCs. From a combined study of Helios, Voyager and IMP data we found that the radial diameter of MCs increases between 0.3 and 4.2 AU proportional to the distance, R, from the Sun as R0.8 (R in AU. The density decrease inside MCs was found to be proportional to R–2.4, thus being stronger compared to the average solar wind. Four different magnetic configurations, as expected from the flux-tube concept, for MCs have been observed in situ by the Helios probes. MCs with left- and right-handed magnetic helicity occurred with about equal frequencies during 1974–1981, but surprisingly, the majority (74% of the MCs had

  14. Dynamic Analysis of Wind Turbines Including Soil-Structure Interaction

    DEFF Research Database (Denmark)

    Harte, M.; Basu, B.; Nielsen, Søren R.K.

    2012-01-01

    blades and includes the effect of centrifugal stiffening due to rotation. The foundation of the structure is modeled as a rigid gravity based foundation with two DOF whose movement is related to the surrounding soil by means of complex impedance functions generated using cone model. Transfer functions...... for displacement of the turbine system are obtained and the modal frequencies of the combined turbine-foundation system are estimated. Simulations are presented for the MDOF turbine structure subjected to wind loading for different soil stiffness conditions. Steady state and turbulent wind loading, developed using...... blade element momentum theory and the Kaimal spectrum, have been considered. Soil stiffness and damping properties acquired from DNV/Risø standards are used as a comparison. The soil-structure interaction is shown to affect the response of the wind turbine. This is examined in terms of the turbine...

  15. Use of the ARM Measurements of Spectral Zenith Radiance for Better Understanding of 3D Cloud-Radiation Processes & Aerosol-Cloud Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Jui-Yuan Christine [University of Reading

    2014-04-10

    This project focuses on cloud-radiation processes in a general three-dimensional cloud situation, with particular emphasis on cloud optical depth and effective particle size. The proposal has two main parts. Part one exploits the large number of new wavelengths offered by the Atmospheric Radiation Measurement (ARM) zenith-pointing ShortWave Spectrometer (SWS), to develop better retrievals not only of cloud optical depth but also of cloud particle size. We also take advantage of the SWS’ high sampling resolution to study the “twilight zone” around clouds where strong aerosol-cloud interactions are taking place. Part two involves continuing our cloud optical depth and cloud fraction retrieval research with ARM’s 2-channel narrow vield-of-view radiometer and sunphotometer instrument by, first, analyzing its data from the ARM Mobile Facility deployments, and second, making our algorithms part of ARM’s operational data processing.

  16. A Location-Based Interactive Model of Internet of Things and Cloud (IoT-Cloud) for Mobile Cloud Computing Applications †

    Science.gov (United States)

    Dinh, Thanh; Kim, Younghan; Lee, Hyukjoon

    2017-01-01

    This paper presents a location-based interactive model of Internet of Things (IoT) and cloud integration (IoT-cloud) for mobile cloud computing applications, in comparison with the periodic sensing model. In the latter, sensing collections are performed without awareness of sensing demands. Sensors are required to report their sensing data periodically regardless of whether or not there are demands for their sensing services. This leads to unnecessary energy loss due to redundant transmission. In the proposed model, IoT-cloud provides sensing services on demand based on interest and location of mobile users. By taking advantages of the cloud as a coordinator, sensing scheduling of sensors is controlled by the cloud, which knows when and where mobile users request for sensing services. Therefore, when there is no demand, sensors are put into an inactive mode to save energy. Through extensive analysis and experimental results, we show that the location-based model achieves a significant improvement in terms of network lifetime compared to the periodic model. PMID:28257067

  17. A Location-Based Interactive Model of Internet of Things and Cloud (IoT-Cloud) for Mobile Cloud Computing Applications.

    Science.gov (United States)

    Dinh, Thanh; Kim, Younghan; Lee, Hyukjoon

    2017-03-01

    This paper presents a location-based interactive model of Internet of Things (IoT) and cloud integration (IoT-cloud) for mobile cloud computing applications, in comparison with the periodic sensing model. In the latter, sensing collections are performed without awareness of sensing demands. Sensors are required to report their sensing data periodically regardless of whether or not there are demands for their sensing services. This leads to unnecessary energy loss due to redundant transmission. In the proposed model, IoT-cloud provides sensing services on demand based on interest and location of mobile users. By taking advantages of the cloud as a coordinator, sensing scheduling of sensors is controlled by the cloud, which knows when and where mobile users request for sensing services. Therefore, when there is no demand, sensors are put into an inactive mode to save energy. Through extensive analysis and experimental results, we show that the location-based model achieves a significant improvement in terms of network lifetime compared to the periodic model.

  18. Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar wind

    Science.gov (United States)

    de la Cita, V. M.; Bosch-Ramon, V.; Paredes-Fortuny, X.; Khangulyan, D.; Perucho, M.

    2017-02-01

    Context. Binaries hosting a massive star and a non-accreting pulsar are powerful non-thermal emitters owing to the interaction of the pulsar and the stellar wind. The winds of massive stars are thought to be inhomogeneous, which could have an impact on the non-thermal emission. Aims: We study numerically the impact of the presence of inhomogeneities or clumps in the stellar wind on the high-energy non-thermal radiation of high-mass binaries hosting a non-accreting pulsar. Methods: We compute the trajectories and physical properties of the streamlines in the shocked pulsar wind without clumps, with a small clump, and with a large clump. This information is used to characterize the injection and the steady state distribution of non-thermal particles accelerated at shocks formed in the pulsar wind. The synchrotron and inverse Compton emission from these non-thermal particles is calculated, accounting also for the effect of gamma-ray absorption through pair creation. A specific study is done for PSR B1259-63/LS2883. Results: When stellar wind clumps perturb the two-wind interaction region, the associated non-thermal radiation in the X-ray band, of synchrotron origin, and in the GeV-TeV band, of inverse Compton origin, is affected by several equally important effects: (I) strong changes in the plasma velocity direction that result in Doppler boosting factor variations; (II) strengthening of the magnetic field that mainly enhances the synchrotron radiation; (III) strengthening of the pulsar wind kinetic energy dissipation at the shock, potentially available for particle acceleration; and (iv) changes in the rate of adiabatic losses that affect the lower energy part of the non-thermal particle population. The radiation above 100 GeV detected, presumably, during the post-periastron crossing of the Be star disc in PSR B1259-63/LS2883, can be roughly reproduced assuming that the crossing of the disc is modelled as the encounter with a large inhomogeneity. Conclusions

  19. Stakeholder interactions to support service creation in cloud computing

    NARCIS (Netherlands)

    Wang, Lei; Ferreira Pires, Luis; Wombacher, Andreas; van Sinderen, Marten J.; Chi, Chihung

    2010-01-01

    Cloud computing is already a major trend in IT. Cloud services are being offered at application (software), platform and infrastructure levels. This paper presents our initial modeling efforts towards service creation at the infrastructure level. The purpose of these modeling efforts is to

  20. The interaction between deep convective clouds and their environment

    NARCIS (Netherlands)

    Böing, S.J.

    2014-01-01

    Deep convective clouds play a key role in tropical weather patterns, summertime rainfall, and the global transport of energy from the tropics to higher latitudes. Current weather and climate models struggle to realistically represent the development and behavior of these clouds. Both the timing of

  1. Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. II. Radiation-Gas Interactions and Outflows

    Science.gov (United States)

    Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron

    2017-12-01

    Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of turbulent star-forming clouds to analyze the detailed interaction between non-ionizing UV radiation and the cloud material. Our simulations trace the evolution of gas and star particles through self-gravitating collapse, star formation, and cloud destruction via radiation-driven outflows. These models are idealized in that we include only radiation feedback and adopt an isothermal equation of state. Turbulence creates a structure of dense filaments and large holes through which radiation escapes, such that only ˜50% of the radiation is (cumulatively) absorbed by the end of star formation. The surface density distribution of gas by mass as seen by the central cluster is roughly lognormal with {σ }{ln{{Σ }}}=1.3{--}1.7, similar to the externally projected surface density distribution. This allows low surface density regions to be driven outwards to nearly 10 times their initial escape speed {v}{esc}. Although the velocity distribution of outflows is broadened by the lognormal surface density distribution, the overall efficiency of momentum injection to the gas cloud is reduced because much of the radiation escapes. The mean outflow velocity is approximately twice the escape speed from the initial cloud radius. Our results are also informative for understanding galactic-scale wind driving by radiation, in particular, the relationship between velocity and surface density for individual outflow structures and the resulting velocity and mass distributions arising from turbulent sources.

  2. Interactive 3D geodesign tool for multidisciplinary wind turbine planning.

    Science.gov (United States)

    Rafiee, Azarakhsh; Van der Male, Pim; Dias, Eduardo; Scholten, Henk

    2018-01-01

    Wind turbine site planning is a multidisciplinary task comprising of several stakeholder groups from different domains and with different priorities. An information system capable of integrating the knowledge on the multiple aspects of a wind turbine plays a crucial role on providing a common picture to the involved groups. In this study, we have developed an interactive and intuitive 3D system (Falcon) for planning wind turbine locations. This system supports iterative design loops (wind turbine configurations), based on the emerging field of geodesign. The integration of GIS, game engine and the analytical models has resulted in an interactive platform with real-time feedback on the multiple wind turbine aspects which performs efficiently for different use cases and different environmental settings. The implementation of tiling techniques and open standard web services support flexible and on-the-fly loading and querying of different (massive) geospatial elements from different resources. This boosts data accessibility and interoperability that are of high importance in a multidisciplinary process. The incorporation of the analytical models in Falcon makes this system independent from external tools for different environmental impacts estimations and results in a unified platform for performing different environmental analysis in every stage of the scenario design. Game engine techniques, such as collision detection, are applied in Falcon for the real-time implementation of different environmental models (e.g. noise and visibility). The interactivity and real-time performance of Falcon in any location in the whole country assist the stakeholders in the seamless exploration of various scenarios and their resulting environmental effects and provides a scope for an interwoven discussion process. The flexible architecture of the system enables the effortless application of Falcon in other countries, conditional to input data availability. The embedded open web

  3. Aerosol-cloud interaction inferred from MODIS satellite data and global aerosol models

    Directory of Open Access Journals (Sweden)

    G. Myhre

    2007-06-01

    Full Text Available We have used the MODIS satellite data and two global aerosol models to investigate the relationships between aerosol optical depth (AOD and cloud parameters that may be affected by the aerosol concentration. The relationships that are studied are mainly between AOD, on the one hand, and cloud cover, cloud liquid water path, and water vapour, on the other. Additionally, cloud droplet effective radius, cloud optical depth, cloud top pressure and aerosol Ångström exponent, have been analysed in a few cases. In the MODIS data we found, as in earlier studies, an enhancement in the cloud cover with increasing AOD. We find it likely that most of the strong increase in cloud cover with AOD, at least for AOD<0.2, is a result of aerosol-cloud interactions and a prolonged cloud lifetime. Large and mesoscale weather systems seem not to be a cause for the increase in cloud cover with AOD in this range. Sensitivity simulations show that when water uptake of the aerosols is not taken into account in the models the modelled cloud cover mostly decreases with AOD. Part of the relationship found in the MODIS data for AOD>0.2 can be explained by larger water uptake close to the clouds since relative humidity is higher in regions with higher cloud cover. The efficiency of the hygroscopic growth depends on aerosol type, the hygroscopic nature of the aerosol, the relative humidity, and to some extent the cloud screening. By analysing the Ångström exponent we find that the hygroscopic growth of the aerosol is not likely to be a main contributor to the cloud cover increase with AOD. Since the largest increase in cloud cover with AOD is for low AOD (~0.2 and thus also for low cloud cover, we argue that cloud contamination is not likely to play a large role. However, interpretation of the complex relationships between AOD and cloud parameters should be made with great care and further work is clearly needed.

  4. The evolution of the protoplanetary disk with mass influx from a molecular cloud core and the photoevaporation winds

    Science.gov (United States)

    Liu, Chunjian; Yao, Zhen; Li, Hongna; Wang, Haosen

    2018-01-01

    We investigate the formation, evolution, and dispersal processes of protoplanetary disks with mass influx from the gravitational collapse of a molecular cloud core and the photoevaporation winds. Due to the initial angular momentum of the molecular cloud core, the gravitational collapse of the molecular cloud core forms a protostar+protoplanetary disk system. We calculate the evolution of the protoplanetary disk from the gravitational collapse of the molecular cloud core to the dispersal stage. In our calculation, we include the mass influx from a molecular cloud core, the irradiation from the central star, the viscosity due to the magnetohydrodynamic (MHD) turbulence driven by the magnetorotational instability (MRI) and the gravitational instability, and the effect of photoevaporation. We find that the protoplanetary disk has some interesting properties, which are different from the previous studies. Firstly, with particular values of parameters of the molecular cloud core, the gravitational instability does not occur during the whole evolution of the resultant protoplanetary disk. With some other parameters of the molecular cloud core, the gravitational instability occurs all the time of the lifetime of the resultant protoplanetary disk. Secondly, the radial distribution of the α parameter exhibits a nearly ladder-like shape, which is different from the three regions' shape in previous studies. Thirdly, the value of the surface density is increased significantly (about a factor of 8.0) compared with that in the Minimum Mass Solar Nebula (MMSN) model. We suggest that this increased surface density can provide enough material for the formation of giant planets within the lifetime of the protoplanetary disk, and may provide a routine for reducing the timescale of the formation of giant planets. We also discuss the influence of the photoevaporation winds on the evolution of the protoplanetary disk.

  5. The initial mass function and global rates of mass, momentum, and energy input to the interstellar medium via stellar winds

    Science.gov (United States)

    Van Buren, D.

    1985-01-01

    Published observational data are compiled and analyzed, using theoretical stellar-evolution models to determine the global rates of mass, momentum, and energy injected into the interstellar medium (ISM) by stellar winds. Expressions derived include psi = 0.00054 x (M to the -1.03) stars formed/sq kpc yr log M (where M is the initial mass function in solar mass units) and mass-loss = (2 x 10 to the -13th) x (L to the 1.25) solar mass/yr (with L in solar luminosity units). It is found that the wind/supernova injection of energy into the ISM and the mass loss from stars of 5 solar mass or more are approximately balanced by the dissipation of energy by cloud-cloud collisions and the formation of stars, respectively.

  6. Inverse modeling of cloud-aerosol interactions -- Part 1: Detailed response surface analysis

    NARCIS (Netherlands)

    Partridge, D.G.; Vrugt, J.A.; Tunved, P.; Ekman, A.M.L.; Gorea, D.; Sooroshian, A.

    2011-01-01

    New methodologies are required to probe the sensitivity of parameters describing cloud droplet activation. This paper presents an inverse modeling-based method for exploring cloud-aerosol interactions via response surfaces. The objective function, containing the difference between the measured and

  7. Inverse modeling of cloud-aerosol interactions – Part 1: Detailed response surface analysis

    Directory of Open Access Journals (Sweden)

    D. G. Partridge

    2011-07-01

    Full Text Available New methodologies are required to probe the sensitivity of parameters describing cloud droplet activation. This paper presents an inverse modeling-based method for exploring cloud-aerosol interactions via response surfaces. The objective function, containing the difference between the measured and model predicted cloud droplet size distribution is studied in a two-dimensional framework, and presented for pseudo-adiabatic cloud parcel model parameters that are pair-wise selected. From this response surface analysis it is shown that the susceptibility of cloud droplet size distribution to variations in different aerosol physiochemical parameters is highly dependent on the aerosol environment and meteorological conditions. In general the cloud droplet size distribution is most susceptible to changes in the updraft velocity. A shift towards an increase in the importance of chemistry for the cloud nucleating ability of particles is shown to exist somewhere between marine average and rural continental aerosol regimes.

    We also use these response surfaces to explore the feasibility of inverse modeling to determine cloud-aerosol interactions. It is shown that the "cloud-aerosol" inverse problem is particularly difficult to solve due to significant parameter interaction, presence of multiple regions of attraction, numerous local optima, and considerable parameter insensitivity.

    The identifiability of the model parameters will be dependent on the choice of the objective function. Sensitivity analysis is performed to investigate the location of the information content within the calibration data to confirm that our choice of objective function maximizes information retrieval from the cloud droplet size distribution.

    Cloud parcel models that employ a moving-centre based calculation of the cloud droplet size distribution pose additional difficulties when applying automatic search algorithms for studying cloud-aerosol interactions

  8. Evolution of Clouds of Migrating Micro-particles with Hydrodynamic and Electrostatic Interactions

    Directory of Open Access Journals (Sweden)

    Chen Sheng

    2017-01-01

    Full Text Available The evolution of a migrating cloud of particles with electrohydrodynamic interactions is numerically investigated. The hydrodynamic interaction is modelled by Oseen dynamics in the limit of small-but-finite particle Reynolds number. The effects of external field and the particle-particle Coulomb repulsion, calculated through pairwise summation, are quantified by a charge parameter, κq. With a small or zero κq, the cloud is seen to flatten into a toroidal configuration and eventually breaks up into two small clouds, indicating that the external electrostatic field has a similar effect with gravity. Increasing the long-range Coulomb repulsion can delay or even totally prevent the breakup. With sufficiently strong repulsion, the cloud undergoes a self-similar expansion. Finally, we show that the breakup of the cloud is strongly related to the initial inhomogeneity of the particle concentration. This chaotic characteristic, however, is dramatically depressed by the long-range Coulomb repulsion.

  9. Effects of Ocean Ecosystem on Marine Aerosol-Cloud Interaction

    Directory of Open Access Journals (Sweden)

    Nicholas Meskhidze

    2010-01-01

    Full Text Available Using satellite data for the surface ocean, aerosol optical depth (AOD, and cloud microphysical parameters, we show that statistically significant positive correlations exist between ocean ecosystem productivity, the abundance of submicron aerosols, and cloud microphysical properties over different parts of the remote oceans. The correlation coefficient for remotely sensed surface chlorophyll a concentration ([Chl-a] and liquid cloud effective radii over productive areas of the oceans varies between −0.2 and −0.6. Special attention is given to identifying (and addressing problems from correlation analysis used in the previous studies that can lead to erroneous conclusions. A new approach (using the difference between retrieved AOD and predicted sea salt aerosol optical depth, AODdiff is developed to explore causal links between ocean physical and biological systems and the abundance of cloud condensation nuclei (CCN in the remote marine atmosphere. We have found that over multiple time periods, 550 nm AODdiff (sensitive to accumulation mode aerosol, which is the prime contributor to CCN correlates well with [Chl-a] over the productive waters of the Southern Ocean. Since [Chl-a] can be used as a proxy of ocean biological productivity, our analysis demonstrates the role of ocean ecology in contributing CCN, thus shaping the microphysical properties of low-level marine clouds.

  10. Development of a Ground Based Remote Sensing Approach for Direct Evaluation of Aerosol-Cloud Interaction

    Directory of Open Access Journals (Sweden)

    Samir Ahmed

    2012-10-01

    Full Text Available The possible interaction and modification of cloud properties due to aerosols is one of the most poorly understood mechanisms within climate studies, resulting in the most significant  uncertainty as regards radiation budgeting. In this study, we explore direct ground based remote sensing methods to assess the Aerosol-Cloud Indirect Effect directly, as space-borne retrievals are not directly suitable for simultaneous aerosol/cloud retrievals. To illustrate some of these difficulties, a statistical assessment of existing multispectral imagers on geostationary (e.g., GOES/Moderate Resolution Imaging Spectroradiometer (MODIS satellite retrievals of the Cloud Droplet Effective Radius (Reff showed significant biases especially at larger solar zenith angles, further motivating the use of ground based remote sensing approaches. In particular, we discuss the potential of using a combined Microwave Radiometer (MWR—Multi-Filter Rotating Shadowband Radiometer (MFRSR system for real-time monitoring of Cloud Optical Depth (COD and Cloud Droplet Effective Radius (Reff, which are combined with aerosol vertical properties from an aerosol lidar. An iterative approach combining the simultaneous observations from MFRSR and MWR are used to retrieve the COD and Reff for thick cloud cases and are extensively validated using the DoE Southern Great Plains (SGP retrievals as well as regression based parameterized model retrievals. In addition, we account for uncertainties in background aerosol, surface albedo and the combined measurement uncertainties from the MWR and MFRSR in order to provide realistic uncertainty estimates, which is found to be ~10% for the parameter range of interest in Aerosol-Cloud Interactions. Finally, we analyze a particular case of possible aerosol-cloud interaction described in the literature at the SGP site and demonstrate that aerosol properties obtained at the surface can lead to inconclusive results in comparison to lidar

  11. ISM Approach to Model Offshore Outsourcing Risks

    Directory of Open Access Journals (Sweden)

    Sunand Kumar

    2014-07-01

    Full Text Available In an effort to achieve a competitive advantage via cost reductions and improved market responsiveness, organizations are increasingly employing offshore outsourcing as a major component of their supply chain strategies. But as evident from literature number of risks such as Political risk, Risk due to cultural differences, Compliance and regulatory risk, Opportunistic risk and Organization structural risk, which adversely affect the performance of offshore outsourcing in a supply chain network. This also leads to dissatisfaction among different stake holders. The main objective of this paper is to identify and understand the mutual interaction among various risks which affect the performance of offshore outsourcing.  To this effect, authors have identified various risks through extant review of literature.  From this information, an integrated model using interpretive structural modelling (ISM for risks affecting offshore outsourcing is developed and the structural relationships between these risks are modeled.  Further, MICMAC analysis is done to analyze the driving power and dependency of risks which shall be helpful to managers to identify and classify important criterions and to reveal the direct and indirect effects of each criterion on offshore outsourcing. Results show that political risk and risk due to cultural differences are act as strong drivers.

  12. Dependence of wind speed and UV albedo at Venus top cloud layer on topography and local time revealed from VMC images

    Science.gov (United States)

    Patsaeva, Marina; Khatuntsev, Igor; Turin, Alexander; Zasova, Ludmila; Bertaux, Jean-loup

    2017-04-01

    A set of UV (365 nm) and IR (965 nm) images obtained by the Venus Monitoring Camera (VMC) was used to study the circulation of the mesosphere at two altitude levels. Displacement vectors were obtained by wind tracking in automated mode for observation period from 2006 to 2014 for UV images [1,2] and from 2006 to 2012 for IR images. The long observation period and good longitude-latitude coverage by single measurements allowed us to focus on the study of the slow-periodic component. The influence of the underlying surface topography on the change of speed of the average zonal wind at UV level at low latitudes, discovered by visual methods has been described in [3]. Analysis of the longitude-latitude distribution of the zonal and meridional components for 172000 (257 orbits) digital individual wind measurements at UV level and for 32,000 (150 orbits) digital individual wind measurements at IR level allows us to compare the influence of Venus topography on the change of the zonal and meridional components at both cloud levels. At the UV level (67±2 km) longitudinal profiles of the zonal speed for different latitude bins in low latitudes correlate with surface profiles. These correlations are most noticeable in the region of Aphrodite Terra. The correlation shift depends on the surface height. Albedo profiles correlate with surface profiles also at high latitudes. Zonal speed profiles at low latitude (5-15°S) depend not only on altitude, but also on local time. Minimum of the zonal speed is observed over Aphrodite Terra (90-100°E) at about 12 LT. A diurnal harmonic with an extremum over Aphrodite Terra was found. It can be considered as a superposition of a solar-synchronous tide and a stationary wave caused by interaction of the windstream with the surface. At the IR level (55±4 km) a correlation between surface topography and meridional speed was found in the region 10-30°S. The average meridional flow is equatorward at the IR level, but in the region Aphrodite

  13. Winds in the Middle Cloud Deck From the Near-IR Imaging by the Venus Monitoring Camera Onboard Venus Express

    Science.gov (United States)

    Khatuntsev, I. V.; Patsaeva, M. V.; Titov, D. V.; Ignatiev, N. I.; Turin, A. V.; Fedorova, A. A.; Markiewicz, W. J.

    2017-11-01

    For more than 8 years the Venus Monitoring Camera (VMC) onboard the Venus Express orbiter performed continuous imaging of the Venus cloud layer in UV, visible and near-IR filters. We applied the correlation approach to sequences of the near-IR images at 965 nm to track cloud features and determine the wind field in the middle and lower cloud (49-57 km). From the VMC images that spanned from December of 2006 through August of 2013 we derived zonal and meridional components of the wind field. In low-to-middle latitudes (5-65°S) the velocity of the retrograde zonal wind was found to be 68-70 m/s. The meridional wind velocity slowly decreases from peak value of +5.8 ± 1.2 m/s at 15°S to 0 at 65-70°S. The mean meridional speed has a positive sign at 5-65°S suggesting equatorward flow. This result, together with the earlier measurements of the poleward flow at the cloud tops, indicates the presence of a closed Hadley cell in the altitude range 55-65 km. Long-term variations of zonal and meridional velocity components were found during 1,200 Earth days of observation. At 20° ± 5°S the zonal wind speed increases from -67.18 ± 1.81 m/s to -77.30 ± 2.49 m/s. The meridional wind gradually increases from +1.30 ± 1.82 m/s to +8.53 ± 2.14 m/s. Following Bertaux et al. (2016) we attribute this long-term trend to the influence from the surface topography on the dynamical process in the atmosphere via the upward propagation of gravity waves that became apparent in the VMC observations due to slow drift of the Venus Express orbit over Aphrodite Terra.

  14. Saturn's North Polar Vortex Revealed by Cassini/VIMS: Zonal Wind Structure and Constraints on Cloud Distributions

    Science.gov (United States)

    Baines, Kevin H.; Momary, T. W.; Fletcher, L. N.; Buratti, B. J.; Roos-Serote, M.; Showman, A. P.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.

    2008-09-01

    We present the first high-spatial resolution, near-nadir imagery and movies of Saturn's north polar region that reveal the wind structure of a north polar vortex. Obtained by Cassini/VIMS on June 15, 2008 from high over Saturn's polar region (sub-spacecraft latitude of 65 degrees N. lat) at an altitude of 0.42 million km during the long polar night, these 210-per-pixel images of the polar region north of 73 degrees N. latitude show several concentric cloud rings and hundreds of individual cloud features in silhouette against the 5-micron background thermal glow of Saturn's deep atmosphere. In contrast to the clear eye of the south polar vortex, the north polar vortex sports a central cloud feature about 650-km in diameter. Zonal winds reach a maximum of 150 m/s near 88 degrees N. latitude (planetocentric) - comparable to the south polar vortex maximum of 190 m/s near 88 degrees S. latitude - and fall off nearly monotonically to 10 m/s near 80 degrees N. latitude. At slightly greater distance from the pole, inside the north polar hexagon in the 75-77 degree N. latitude region, zonal winds increase dramatically to 130 m/s, as silhouetted clouds are seen speeding aroud the "race track” of the hexagonal feature. VIMS 5-micron thermal observations over a 1.6-year period from October 29, 2006 to June 15, 2008 are consistent with the polar hexagon structure itself remaining fixed in the Voyager-era radio rotation rate (Desch and Kaiser, Geophys. Res. Lett, 8, 253-256, 1981) to within an accuracy of 3 seconds per rotational period. This agrees with the stationary nature of the wave in this rotation system found by Godfrey (Icarus 76, 335-356, 1988), but is inconsistent with rotation rates found during the current Cassini era.

  15. Collaboratives for Wildlife-Wind Turbine Interaction Research: Fostering Multistakeholder Involvement (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, K.

    2013-04-01

    This poster highlights the various wildlife-wind collaboratives (specific to wildlife-wind turbine interaction research) that currently exist. Examples of collaboratives are included along with contact information, objectives, benefits, and ways to advance the knowledge base.

  16. The interaction of wind and water in the desertification environment

    Science.gov (United States)

    Jacobberger, P. A.

    1987-01-01

    An appropriate process/response model for the physical basis of desertification is provided by the interactions of wind and water in the desert fringe environment. Essentially, the process of desertification can be thought of as a progressive environmental transition from predominantly fluvial to aeolian processes. This is a simple but useful way of looking at desertification; in this context, desertification is morphogenetic in character. To illustrate the model, a study of drought-related changes in central Mali will serve to trace the interrelated responses of geomorphologic processes to drought conditions.

  17. Cloud and boundary layer interactions over the Arctic sea ice in late summer

    Directory of Open Access Journals (Sweden)

    M. D. Shupe

    2013-09-01

    Full Text Available Observations from the Arctic Summer Cloud Ocean Study (ASCOS, in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud–atmosphere–surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near-surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean–ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back-trajectory analyses suggest that these warm air masses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these air masses, providing necessary support for cloud formation. On the occasions when cloud–surface coupling did occur, back trajectories indicated that these air masses advected at

  18. In-situ Measurements of Aerosol-Cloud-Precipitation Interactions During the 2011 E-PEACE Campaign: Case Studies of Clouds Perturbed by Ship Emissions

    Science.gov (United States)

    Metcalf, A. R.; Sorooshian, A.; Craven, J. S.; Coggon, M.; Lin, J. J.; Wang, Z.; Shingler, T.; Song, S.; Jung, E.; Albrecht, B. A.; Jonsson, H.; Nenes, A.; Seinfeld, J.

    2011-12-01

    The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed aerosol-cloud-precipitation interactions during the 2011 Eastern-Pacific Emitted Aerosol Cloud Experiment (E-PEACE) off the central coast of California. During the project, ship exhaust in a major north-south shipping lane used by large cargo and tanker ships off the coast of Monterey, CA was probed in order to study its effect on the marine stratocumulus commonly found in the summer months. During the course of a single experiment, fresh ship exhaust was sampled near the ship and followed downwind for approximately 20 miles before ascending to sample the plume at multiple heights in cloud. The chemical and physical properties of the ship exhaust was characterized below cloud by an Aerosol Mass Spectrometer (AMS), a Cloud Condensation Nuclei Counter (CCNC), multiple Condensation Particle Counters (CPCs), parallel Differential Mobility Analyzers (DMAs), a Passive Cavity Aerosol Spectrometer Probe, a Single Particle Soot Photometer (SP2), and a Photoacoustic Soot Spectrometer (PASS3). An upward-facing Doppler cloud radar (3 mm wavelength) captured the vertical microphysical and velocity structure of the clouds. The cloud droplet number and size distributions were characterized within the cloud with a Cloud, Aerosol, and Precipitation Spectrometer, a Forward Scattering Spectrometer Probe, and a Phase Doppler Interferometer, as were the cloud droplet nuclei chemistry and physical properties by several instruments (AMS, DMA, PASS3, SP2, CCNC, and CPC) sampling behind a Counterflow Virtual Impactor inlet. This presentation provides an overview of our findings.

  19. Ocean Emission Effects on Aerosol-Cloud Interactions: Insights from Two Case Studies

    Directory of Open Access Journals (Sweden)

    Armin Sorooshian

    2010-01-01

    Full Text Available Two case studies are discussed that evaluate the effect of ocean emissions on aerosol-cloud interactions. A review of the first case study from the eastern Pacific Ocean shows that simultaneous aircraft and space-borne observations are valuable in detecting links between ocean biota emissions and marine aerosols, but that the effect of the former on cloud microphysics is less clear owing to interference from background anthropogenic pollution and the difficulty with field experiments in obtaining a wide range of aerosol conditions to robustly quantify ocean effects on aerosol-cloud interactions. To address these limitations, a second case was investigated using remote sensing data over the less polluted Southern Ocean region. The results indicate that cloud drop size is reduced more for a fixed increase in aerosol particles during periods of higher ocean chlorophyll A. Potential biases in the results owing to statistical issues in the data analysis are discussed.

  20. Regional scale effects of the aerosol cloud interaction simulated with an online coupled comprehensive chemistry model

    Directory of Open Access Journals (Sweden)

    M. Bangert

    2011-05-01

    Full Text Available We have extended the coupled mesoscale atmosphere and chemistry model COSMO-ART to account for the transformation of aerosol particles into cloud condensation nuclei and to quantify their interaction with warm cloud microphysics on the regional scale. The new model system aims to fill the gap between cloud resolving models and global scale models. It represents the very complex microscale aerosol and cloud physics as detailed as possible, whereas the continental domain size and efficient codes will allow for both studying weather and regional climate. The model system is applied in a first extended case study for Europe for a cloudy five day period in August 2005.

    The model results show that the mean cloud droplet number concentration of clouds is correlated with the structure of the terrain, and we present a terrain slope parameter TS to classify this dependency. We propose to use this relationship to parameterize the probability density function, PDF, of subgrid-scale cloud updraft velocity in the activation parameterizations of climate models.

    The simulations show that the presence of cloud condensation nuclei (CCN and clouds are closely related spatially. We find high aerosol and CCN number concentrations in the vicinity of clouds at high altitudes. The nucleation of secondary particles is enhanced above the clouds. This is caused by an efficient formation of gaseous aerosol precursors above the cloud due to more available radiation, transport of gases in clean air above the cloud, and humid conditions. Therefore the treatment of complex photochemistry is crucial in atmospheric models to simulate the distribution of CCN.

    The mean cloud droplet number concentration and droplet diameter showed a close link to the change in the aerosol. To quantify the net impact of an aerosol change on the precipitation we calculated the precipitation susceptibility β for the whole model domain over a period of two days with

  1. Solar Wind Interaction and Impact on the Venus Atmosphere

    Science.gov (United States)

    Futaana, Yoshifumi; Stenberg Wieser, Gabriella; Barabash, Stas; Luhmann, Janet G.

    2017-11-01

    Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years. Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models

  2. Solar Wind Interaction and Impact on the Venus Atmosphere

    Science.gov (United States)

    Futaana, Yoshifumi; Stenberg Wieser, Gabriella; Barabash, Stas; Luhmann, Janet G.

    2017-08-01

    Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years. Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models

  3. Geometrical aspects of the interaction between expanding clouds and environment

    CERN Document Server

    Spineanu, F

    2015-01-01

    This work is intended to be a contribution to the study of the morphology of the rising convective columns, for a better representation of the processes of entrainment and detrainment. We examine technical methods for the description of the interface of expanding clouds and reveal the role of \\emph{fingering} instability which increases the effective length of the periphery of the cloud. Assuming Laplacian growth we give a detailed derivation of the time-dependent conformal transformation that solves the equation of the \\emph{fingering} instability. For the phase of slower expansion, the evolution of complex poles with a dynamics largely controlled by the Hilbert operator (acting on the function that represents the interface position) leads to \\emph{cusp} singularities but smooths out the smaller scale perturbations. We review the arguments that the rising column cannot preserve its integrity (seen as compacity in any horizontal section), because of the penetrative downdrafts or the incomplete repulsion of th...

  4. Influence of sea surface wind wave turbulence upon wind-induced circulation, tide-surge interaction and bed stress

    Science.gov (United States)

    Xing, Jiuxing; Davies, Alan M.; Jones, John Eric

    2012-07-01

    A three-dimensional finite volume unstructured mesh model of the west coast of Britain, with high resolution in the coastal regions, is used to investigate the role of wind wave turbulence and wind and tide forced currents in producing maximum bed stress in the eastern Irish Sea. The spatial distribution of the maximum bed stress, which is important in sediment transport problems, is determined, together with how it is modified by the direction of wind forced currents, tide-surge interaction and a surface source of wind wave turbulence associated with wave breaking. Initial calculations show that to first order the distribution of maximum bed stress is determined by the tide. However, since maximum sediment transport occurs at times of episodic events, such as storm surges, their effects upon maximum bed stresses are examined for the case of strong northerly, southerly and westerly wind forcing. Calculations show that due to tide-surge interaction both the tidal distribution and the surge are modified by non-linear effects. Consequently, the magnitude and spatial distribution of maximum bed stress during major wind events depends upon wind direction. In addition calculations show that a surface source of turbulence due to wind wave breaking in shallow water can influence the maximum bed stress. In turn, this influences the wind forced flow and hence the movement of suspended sediment. Calculations of the spatial variability of maximum bed stress indicate the level of measurements required for model validation.

  5. The interaction of katabatic winds and mountain waves

    Energy Technology Data Exchange (ETDEWEB)

    Poulos, Gregory Steve [Colorado State Univ., Fort Collins, CO (United States)

    1997-01-01

    The variation in the oft-observed, thermally-forced, nocturnal katabatic winds along the east side of the Rocky Mountains can be explained by either internal variability or interactions with various other forcings. Though generally katabatic flows have been studied as an entity protected from external forcing by strong thermal stratification, this work investigates how drainage winds along the Colorado Front Range interact with, in particular, topographically forced mountain waves. Previous work has shown, based on measurements taken during the Atmospheric Studies in Complex Terrain 1993 field program, that the actual dispersion in katabatic flows is often greater than reflected in models of dispersion. The interaction of these phenomena is complicated and non-linear since the amplitude, wavelength and vertical structure of mountain waves developed by flow over the Rocky Mountain barrier are themselves partly determined by the evolving atmospheric stability in which the drainage flows develop. Perturbations to katabatic flow by mountain waves, relative to their more steady form in quiescent conditions, are found to be caused by both turbulence and dynamic pressure effects. The effect of turbulent interaction is to create changes to katabatic now depth, katabatic flow speed, katabatic jet height and, vertical thermal stratification. The pressure effect is found to primarily influence the variability of a given katabatic now through the evolution of integrated column wave forcing on surface pressure. Variability is found to occur on two scales, on the mesoscale due to meso-gamma scale mountain wave evolution, and on the microscale, due to wave breaking. Since existing parameterizations for the statically stable case are predominantly based on nearly flat terrain atmospheric measurements under idealized or nearly quiescent conditions, it is no surprise that these parameterizations often contribute to errors in prediction, particularly in complex terrain.

  6. Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Fast, JD [Pacific Northwest National Laboratory; Berg, LK [Pacific Northwest National Laboratory

    2015-12-01

    Cumulus convection is an important component in the atmospheric radiation budget and hydrologic cycle over the Southern Great Plains and over many regions of the world, particularly during the summertime growing season when intense turbulence induced by surface radiation couples the land surface to clouds. Current convective cloud parameterizations contain uncertainties resulting in part from insufficient coincident data that couples cloud macrophysical and microphysical properties to inhomogeneities in boundary layer and aerosol properties. The Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign is designed to provide a detailed set of measurements that are needed to obtain a more complete understanding of the life cycle of shallow clouds by coupling cloud macrophysical and microphysical properties to land surface properties, ecosystems, and aerosols. HI-SCALE consists of 2, 4-week intensive observational periods, one in the spring and the other in the late summer, to take advantage of different stages and distribution of “greenness” for various types of vegetation in the vicinity of the Atmospheric Radiation and Measurement (ARM) Climate Research Facility’s Southern Great Plains (SGP) site as well as aerosol properties that vary during the growing season. Most of the proposed instrumentation will be deployed on the ARM Aerial Facility (AAF) Gulfstream 1 (G-1) aircraft, including those that measure atmospheric turbulence, cloud water content and drop size distributions, aerosol precursor gases, aerosol chemical composition and size distributions, and cloud condensation nuclei concentrations. Routine ARM aerosol measurements made at the surface will be supplemented with aerosol microphysical properties measurements. The G-1 aircraft will complete transects over the SGP Central Facility at multiple altitudes within the boundary layer, within clouds, and above clouds.

  7. Rate of non-linearity in DMS aerosol-cloud-climate interactions

    Directory of Open Access Journals (Sweden)

    M. A. Thomas

    2011-11-01

    Full Text Available The degree of non-linearity in DMS-cloud-climate interactions is assessed using the ECHAM5-HAMMOZ model by taking into account end-to-end aerosol chemistry-cloud microphysics link. The evaluation is made over the Southern oceans in austral summer, a region of minimal anthropogenic influence. In this study, we compare the DMS-derived changes in the aerosol and cloud microphysical properties between a baseline simulation with the ocean DMS emissions from a prescribed climatology, and a scenario where the DMS emissions are doubled. Our results show that doubling the DMS emissions in the current climate results in a non-linear response in atmospheric DMS burden and subsequently, in SO2 and H2SO4 burdens due to inadequate OH oxidation. The aerosol optical depth increases by only ~20 % in the 30° S–75° S belt in the SH summer months. This increases the vertically integrated cloud droplet number concentrations (CDNC by 25 %. Since the vertically integrated liquid water vapor is constant in our model simulations, an increase in CDNC leads to a reduction in cloud droplet radius of 3.4 % over the Southern oceans in summer. The equivalent increase in cloud liquid water path is 10.7 %. The above changes in cloud microphysical properties result in a change in global annual mean radiative forcing at the TOA of −1.4 W m−2. The results suggest that the DMS-cloud microphysics link is highly non-linear. This has implications for future studies investigating the DMS-cloud climate feedbacks in a warming world and for studies evaluating geoengineering options to counteract warming by modulating low level marine clouds.

  8. Large Scale Variability of Phytoplankton Blooms in the Arctic and Peripheral Seas: Relationships with Sea Ice, Temperature, Clouds, and Wind

    Science.gov (United States)

    Comiso, Josefino C.; Cota, Glenn F.

    2004-01-01

    Spatially detailed satellite data of mean color, sea ice concentration, surface temperature, clouds, and wind have been analyzed to quantify and study the large scale regional and temporal variability of phytoplankton blooms in the Arctic and peripheral seas from 1998 to 2002. In the Arctic basin, phytoplankton chlorophyll displays a large symmetry with the Eastern Arctic having about fivefold higher concentrations than those of the Western Arctic. Large monthly and yearly variability is also observed in the peripheral seas with the largest blooms occurring in the Bering Sea, Sea of Okhotsk, and the Barents Sea during spring. There is large interannual and seasonal variability in biomass with average chlorophyll concentrations in 2002 and 2001 being higher than earlier years in spring and summer. The seasonality in the latitudinal distribution of blooms is also very different such that the North Atlantic is usually most expansive in spring while the North Pacific is more extensive in autumn. Environmental factors that influence phytoplankton growth were examined, and results show relatively high negative correlation with sea ice retreat and strong positive correlation with temperature in early spring. Plankton growth, as indicated by biomass accumulation, in the Arctic and subarctic increases up to a threshold surface temperature of about 276-277 degree K (3-4 degree C) beyond which the concentrations start to decrease suggesting an optimal temperature or nutrient depletion. The correlation with clouds is significant in some areas but negligible in other areas, while the correlations with wind speed and its components are generally weak. The effects of clouds and winds are less predictable with weekly climatologies because of unknown effects of averaging variable and intermittent physical forcing (e.g. over storm event scales with mixing and upwelling of nutrients) and the time scales of acclimation by the phytoplankton.

  9. Implementing lean manufacturing system: ISM approach

    Directory of Open Access Journals (Sweden)

    Naveen Kumar

    2013-09-01

    Full Text Available Purpose: Lean Manufacturing System has emerged as an important area of research in Indian context. The requirement of Lean Manufacturing has increased due to defects in products (semi finished and finished and subsequent increase in cost. In this context, this study is an attempt to develop a structural model of the variables, important to implement Lean Manufacturing System in Indian automobile industry. Design/Methodology/Approach: Various variables of lean manufacturing system implementation have been identified from literature review and experts’ opinions. Contextual relationship among these identified variables has been set after carrying out brainstorming session. Further, classification of the variables has been carried out based upon the driving power and dependence. In addition to this, a structural model of variables to implement lean concept in Indian automobile industry has also been developed using Interpretive Structural Modeling (ISM technique. Questionnaire based survey has also been conducted to rank these variables. Findings: Eighteen variables have been identified from the literature and subsequent discussions with experts. Out of which, nine variables have been identified as dependent and nine variables have been identified as driver. No variable has been identified as linkage variable and autonomous variable. From the model developed, ‘Relative cost benefits’ has been identified as top level dependent variable and top management commitment as bottom level most independent variable. Research limitations/Implications: The model so developed is a hypothetical model based upon experts’ opinions. The conclusions so drawn may be further modified to apply in real situation. Practical implication: Clear understanding of interactions among these variables will help organizations to prioritize and manage these variables more effectively and efficiently to draw advantage from lean manufacturing system implementation

  10. WINDS, CLUMPS, AND INTERACTING COSMIC RAYS IN M82

    Energy Technology Data Exchange (ETDEWEB)

    Yoast-Hull, Tova M.; Everett, John E.; Zweibel, Ellen G. [Department of Physics, University of Wisconsin-Madison, WI (United States); Gallagher, J. S. III, E-mail: yoasthull@wisc.edu [Department of Astronomy, University of Wisconsin-Madison, WI (United States)

    2013-05-01

    We construct a family of models for the evolution of energetic particles in the starburst galaxy M82 and compare them to observations to test the calorimeter assumption that all cosmic ray energy is radiated in the starburst region. Assuming constant cosmic ray acceleration efficiency with Milky Way parameters, we calculate the cosmic-ray proton and primary and secondary electron/positron populations as a function of energy. Cosmic rays are injected with Galactic energy distributions and electron-to-proton ratio via Type II supernovae at the observed rate of 0.07 yr{sup -1}. From the cosmic ray spectra, we predict the radio synchrotron and {gamma}-ray spectra. To more accurately model the radio spectrum, we incorporate a multiphase interstellar medium in the starburst region of M82. Our model interstellar medium is highly fragmented with compact dense molecular clouds and dense photoionized gas, both embedded in a hot, low density medium in overall pressure equilibrium. The spectra predicted by this one-zone model are compared to the observed radio and {gamma}-ray spectra of M82. {chi}{sup 2} tests are used with radio and {gamma}-ray observations and a range of model predictions to find the best-fit parameters. The best-fit model yields constraints on key parameters in the starburst zone of M82, including a magnetic field strength of {approx}250 {mu}G and a wind advection speed in the range of 300-700 km s{sup -1}. We find that M82 is a good electron calorimeter but not an ideal cosmic-ray proton calorimeter and discuss the implications of our results for the astrophysics of the far-infrared-radio correlation in starburst galaxies.

  11. Enhanced PM2.5 pollution in China due to aerosol-cloud interactions.

    Science.gov (United States)

    Zhao, Bin; Liou, Kuo-Nan; Gu, Yu; Li, Qinbin; Jiang, Jonathan H; Su, Hui; He, Cenlin; Tseng, Hsien-Liang R; Wang, Shuxiao; Liu, Run; Qi, Ling; Lee, Wei-Liang; Hao, Jiming

    2017-06-30

    Aerosol-cloud interactions (aerosol indirect effects) play an important role in regional meteorological variations, which could further induce feedback on regional air quality. While the impact of aerosol-cloud interactions on meteorology and climate has been extensively studied, their feedback on air quality remains unclear. Using a fully coupled meteorology-chemistry model, we find that increased aerosol loading due to anthropogenic activities in China substantially increases column cloud droplet number concentration and liquid water path (LWP), which further leads to a reduction in the downward shortwave radiation at surface, surface air temperature and planetary boundary layer (PBL) height. The shallower PBL and accelerated cloud chemistry due to larger LWP in turn enhance the concentrations of particulate matter with diameter less than 2.5 μm (PM2.5) by up to 33.2 μg m(-3) (25.1%) and 11.0 μg m(-3) (12.5%) in January and July, respectively. Such a positive feedback amplifies the changes in PM2.5 concentrations, indicating an additional air quality benefit under effective pollution control policies but a penalty for a region with a deterioration in PM2.5 pollution. Additionally, we show that the cloud processing of aerosols, including wet scavenging and cloud chemistry, could also have substantial effects on PM2.5 concentrations.

  12. Radiative Interaction of Shocks with Small Interstellar Clouds as a Pre-stage to Star Formation

    Science.gov (United States)

    Johansson, Erik P. G.; Ziegler, Udo

    2013-03-01

    Cloud compression by external shocks is believed to be an important triggering mechanism for gravitational collapse and star formation in the interstellar medium. We have performed MHD simulations to investigate whether the radiative interaction between a shock wave and a small interstellar cloud can induce the conditions for Jeans instability and how the interaction is influenced by magnetic fields of different strengths and orientation. The simulations use the NIRVANA code in three dimensions with anisotropic heat conduction and radiative heating/cooling at an effective resolution of 100 cells per cloud radius. Our cloud has radius 1.5 pc, has density 17 cm-3, is embedded in a medium of density 0.17 cm-3, and is struck by a planar Mach 30 shock wave. The simulations produce dense, cold fragments similar to those of Mellema et al. and Fragile et al. We do not find any regions that are Jeans unstable but do record transient cloud density enhancements of factors ~103-105 for the bulk of the cloud mass, which then decline and converge toward seemingly stable net density enhancement factors ~102-104. Our run with a weak, initial magnetic field (β = 103) perpendicular to the shock normal stands out as producing the most lasting density enhancements. We interpret this field strength as being the compromise between weak internal magnetic pressure preventing compression and sufficiently strong magnetic field to thermally insulate the condensations, thus helping them cool radiatively.

  13. Selected topics on the interaction between cirrus clouds and embedded contrails

    Directory of Open Access Journals (Sweden)

    K. Gierens

    2012-12-01

    Full Text Available Persistent contrails and natural cirrus clouds often coexist in the upper troposphere and contrails can be embedded within cirrus clouds. The present paper deals with some questions regarding the interaction of cirrus clouds and embedded contrails. I have selected only questions that can be answered by analytical means. I find that (1 the emission index for water vapour is only slightly changed when an aircraft crosses a cirrus cloud, (2 that contrail formation is not affected by an ambient cirrus, (3 that cirrus ice crystals entrained into the trailing wing tip vortex do not efficiently retard the sublimation of contrail ice crystals, and (4 that cirrus can start to dissolve an embedded contrail after a couple of hours by aggregation.

  14. Analysis of a utility-interactive wind-photovoltaic hybrid system with battery storage using neural network

    Science.gov (United States)

    Giraud, Francois

    1999-10-01

    This dissertation investigates the application of neural network theory to the analysis of a 4-kW Utility-interactive Wind-Photovoltaic System (WPS) with battery storage. The hybrid system comprises a 2.5-kW photovoltaic generator and a 1.5-kW wind turbine. The wind power generator produces power at variable speed and variable frequency (VSVF). The wind energy is converted into dc power by a controlled, tree-phase, full-wave, bridge rectifier. The PV power is maximized by a Maximum Power Point Tracker (MPPT), a dc-to-dc chopper, switching at a frequency of 45 kHz. The whole dc power of both subsystems is stored in the battery bank or conditioned by a single-phase self-commutated inverter to be sold to the utility at a predetermined amount. First, the PV is modeled using Artificial Neural Network (ANN). To reduce model uncertainty, the open-circuit voltage VOC and the short-circuit current ISC of the PV are chosen as model input variables of the ANN. These input variables have the advantage of incorporating the effects of the quantifiable and non-quantifiable environmental variants affecting the PV power. Then, a simplified way to predict accurately the dynamic responses of the grid-linked WPS to gusty winds using a Recurrent Neural Network (RNN) is investigated. The RNN is a single-output feedforward backpropagation network with external feedback, which allows past responses to be fed back to the network input. In the third step, a Radial Basis Functions (RBF) Network is used to analyze the effects of clouds on the Utility-Interactive WPS. Using the irradiance as input signal, the network models the effects of random cloud movement on the output current, the output voltage, the output power of the PV system, as well as the electrical output variables of the grid-linked inverter. Fourthly, using RNN, the combined effects of a random cloud and a wind gusts on the system are analyzed. For short period intervals, the wind speed and the solar radiation are considered as

  15. Hubble space telescope imaging of decoupled dust clouds in the ram pressure stripped Virgo spirals NGC 4402 and NGC 4522

    Energy Technology Data Exchange (ETDEWEB)

    Abramson, Anne; Kenney, Jeffrey D. P., E-mail: anne.abramson@yale.edu, E-mail: jeff.kenney@yale.edu [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)

    2014-03-01

    We present the highest-resolution study to date of the interstellar medium (ISM) in galaxies undergoing ram pressure stripping, using Hubble Space Telescope BVI imaging of NGC 4522 and NGC 4402, Virgo Cluster spirals that are well known to be experiencing intracluster medium (ICM) ram pressure. We find that throughout most of both galaxies, the main dust lane has a fairly well-defined edge, with a population of giant molecular cloud (GMC) sized (tens- to hundreds-of-pc scale), isolated, highly extincting dust clouds located up to ∼1.5 kpc radially beyond it. Outside of these dense clouds, the area has little or no diffuse dust extinction, indicating that the clouds have decoupled from the lower-density ISM material that has already been stripped. Several of the dust clouds have elongated morphologies that indicate active ram pressure, including two large (kpc scale) filaments in NGC 4402 that are elongated in the projected ICM wind direction. We calculate a lower limit on the H I + H{sub 2} masses of these clouds based on their dust extinctions and find that a correction factor of ∼10 gives cloud masses consistent with those measured in CO for clouds of similar diameters, probably due to the complicating factors of foreground light, cloud substructure, and resolution limitations. Assuming that the clouds' actual masses are consistent with those of GMCs of similar diameters (∼10{sup 4}-10{sup 5} M {sub ☉}), we estimate that only a small fraction (∼1%-10%) of the original H I + H{sub 2} remains in the parts of the disks with decoupled clouds. Based on Hα images, a similar fraction of star formation persists in these regions, 2%-3% of the estimated pre-stripping star formation rate. We find that the decoupled cloud lifetimes may be up to 150-200 Myr.

  16. Wind Farm Structures’ Impact on Harmonic Emission and Grid Interaction

    DEFF Research Database (Denmark)

    Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

    The impact of a wind farm’s internal structures on harmonic emission at the point of common coupling and on the whole system frequency characteristic is investigated in this paper. The largest wind farms in the world, Horns Rev 2 Offshore Wind Farm and Polish Karnice Onshore Wind Farm......, are thoroughly analyzed. Different wind farm configurations are taken into consideration in order to entirely describe phenomena associated with harmonics. Some aspects of wind farm modelling for harmonic studies are also presented in this paper. The simulation results are compared with measurement data in order...

  17. Spin Diffusion in Trapped Clouds of Cold Atoms with Resonant Interactions

    DEFF Research Database (Denmark)

    Bruun, Georg Morten; Pethick, C. J.

    2011-01-01

    We show that puzzling recent experimental results on spin diffusion in a strongly interacting atomic gas may be understood in terms of the predicted spin diffusion coefficient for a generic strongly interacting system. Three important features play a central role: (a) Fick’s law for diffusion mus...... be modified to allow for the trapping potential; (b) the diffusion coefficient is inhomogeneous, due to the density variations in the cloud; and (c) the diffusion approximation fails in the outer parts of the cloud, where the mean free path is long....

  18. Brahan Project High Frequency Radar Ocean Measurements: Currents, Winds, Waves and Their Interactions

    OpenAIRE

    Belinda Lipa; Donald Barrick; Andres Alonso-Martirena; Maria Fernandes; Maria Inmaculada Ferrer; Bruce Nyden

    2014-01-01

    We describe radar measurements of waves, currents and winds made on the coast of northern Scotland during two 2013/14 winter storms, giving methods, results and interpretation. Wave parameters (height, period, direction and short-wave/wind direction) were derived and compared with measurements made by a neighboring buoy and local weather stations. Wind direction and current velocity maps were produced and the interactions of winds and currents discussed. Significant oscillations in wave param...

  19. Local Interactions of Hydrometeors by Diffusion in Mixed-Phase Clouds

    Science.gov (United States)

    Baumgartner, Manuel; Spichtinger, Peter

    2017-04-01

    Mixed-phase clouds, containing both ice particles and liquid droplets, are important for the Earth-Atmosphere system. They modulate the radiation budget by a combination of albedo effect and greenhouse effect. In contrast to liquid water clouds, the radiative impact of clouds containing ice particles is still uncertain. Scattering and absorption highly depends in microphysical properties of ice crystals, e.g. size and shape. In addition, most precipitation on Earth forms via the ice phase. Thus, better understanding of ice processes as well as their representation in models is required. A key process for determining shape and size of ice crystals is diffusional growth. Diffusion processes in mixed-phase clouds are highly uncertain; in addition they are usually highly simplified in cloud models, especially in bulk microphysics parameterizations. The direct interaction between cloud droplets and ice particles, due to spatial inhomogeneities, is ignored; the particles can only interact via their environmental conditions. Local effects as supply of supersaturation due to clusters of droplets around ice particles are usually not represented, although they form the physical basis of the Wegener-Bergeron-Findeisen process. We present direct numerical simulations of the interaction of single ice particles and droplets, especially their local competition for the available water vapor. In addition, we show an approach to parameterize local interactions by diffusion. The suggested parameterization uses local steady-state solutions of the diffusion equations for water vapor for an ice particle as well as a droplet. The individual solutions are coupled together to obtain the desired interaction. We show some results of the scheme as implemented in a parcel model.

  20. Unveiling aerosol-cloud interactions - Part 1: Cloud contamination in satellite products enhances the aerosol indirect forcing estimate

    Science.gov (United States)

    Christensen, Matthew W.; Neubauer, David; Poulsen, Caroline A.; Thomas, Gareth E.; McGarragh, Gregory R.; Povey, Adam C.; Proud, Simon R.; Grainger, Roy G.

    2017-11-01

    Increased concentrations of aerosol can enhance the albedo of warm low-level cloud. Accurately quantifying this relationship from space is challenging due in part to contamination of aerosol statistics near clouds. Aerosol retrievals near clouds can be influenced by stray cloud particles in areas assumed to be cloud-free, particle swelling by humidification, shadows and enhanced scattering into the aerosol field from (3-D radiative transfer) clouds. To screen for this contamination we have developed a new cloud-aerosol pairing algorithm (CAPA) to link cloud observations to the nearest aerosol retrieval within the satellite image. The distance between each aerosol retrieval and nearest cloud is also computed in CAPA. Results from two independent satellite imagers, the Advanced Along-Track Scanning Radiometer (AATSR) and Moderate Resolution Imaging Spectroradiometer (MODIS), show a marked reduction in the strength of the intrinsic aerosol indirect radiative forcing when selecting aerosol pairs that are located farther away from the clouds (-0.28±0.26 W m-2) compared to those including pairs that are within 15 km of the nearest cloud (-0.49±0.18 W m-2). The larger aerosol optical depths in closer proximity to cloud artificially enhance the relationship between aerosol-loading, cloud albedo, and cloud fraction. These results suggest that previous satellite-based radiative forcing estimates represented in key climate reports may be exaggerated due to the inclusion of retrieval artefacts in the aerosol located near clouds.

  1. Who Moved Those Rain Clouds to Town? Making Windbirds to Learn about the Power of Wind

    Science.gov (United States)

    Samarakoon, Deepanee; Smith, Latisha L.

    2016-01-01

    In this practical article, a kindergarten teacher shares a lesson designed to teach students about the power of wind. To address the Next Generation Science Standards engineering standards, students discussed the negative and positive aspects of wind and made daily weather observations (K-ESS2-1). Students constructed bird-shaped windsocks, called…

  2. Simulation of interaction between wind farm and power system

    DEFF Research Database (Denmark)

    Sørensen, Poul Ejnar; Hansen, Anca Daniela; Janosi, L.

    2002-01-01

    A dynamic model of the wind farm Hagesholm has been implemented in the dedicated power system simulation program DIgSILENT. The wind farm con- sists of six 2MW NM2000/72 wind turbines from NEG-Micon. The model has been verified using simultaneous powerquality measurements on the 10 kV terminals...... of a single wind turbine and power performance measurements on two wind turbines. The verification shows a generally good agreement between simulations and measurements, although the simulations at higher windspeeds seem to underestimate the power and voltage fluctuations. A way to improve the simulation...

  3. An Interactive Web-Based Analysis Framework for Remote Sensing Cloud Computing

    Science.gov (United States)

    Wang, X. Z.; Zhang, H. M.; Zhao, J. H.; Lin, Q. H.; Zhou, Y. C.; Li, J. H.

    2015-07-01

    Spatiotemporal data, especially remote sensing data, are widely used in ecological, geographical, agriculture, and military research and applications. With the development of remote sensing technology, more and more remote sensing data are accumulated and stored in the cloud. An effective way for cloud users to access and analyse these massive spatiotemporal data in the web clients becomes an urgent issue. In this paper, we proposed a new scalable, interactive and web-based cloud computing solution for massive remote sensing data analysis. We build a spatiotemporal analysis platform to provide the end-user with a safe and convenient way to access massive remote sensing data stored in the cloud. The lightweight cloud storage system used to store public data and users' private data is constructed based on open source distributed file system. In it, massive remote sensing data are stored as public data, while the intermediate and input data are stored as private data. The elastic, scalable, and flexible cloud computing environment is built using Docker, which is a technology of open-source lightweight cloud computing container in the Linux operating system. In the Docker container, open-source software such as IPython, NumPy, GDAL, and Grass GIS etc., are deployed. Users can write scripts in the IPython Notebook web page through the web browser to process data, and the scripts will be submitted to IPython kernel to be executed. By comparing the performance of remote sensing data analysis tasks executed in Docker container, KVM virtual machines and physical machines respectively, we can conclude that the cloud computing environment built by Docker makes the greatest use of the host system resources, and can handle more concurrent spatial-temporal computing tasks. Docker technology provides resource isolation mechanism in aspects of IO, CPU, and memory etc., which offers security guarantee when processing remote sensing data in the IPython Notebook. Users can write

  4. Interaction of the solar wind with Venus. [plasma measurements by Mariner space probes

    Science.gov (United States)

    Bridge, H. S.; Lazarus, A. J.; Siscoe, G. L.; Hartle, R. E.; Ogilvie, K. W.; Scudder, J. D.; Yeates, C. M.

    1976-01-01

    Two topics related to the interaction of the solar wind with Venus are considered. First, a short review of the experimental evidence with particular attention to plasma measurements carried out on Mariner-5 and Mariner-10 is given. Secondly, the results of some recent theoretical work on the interaction of the solar wind with the ionosphere of Venus are summarized.

  5. Aircraft-based investigation of Dynamics-Aerosol-Chemistry-Cloud Interactions in Southern West Africa

    Science.gov (United States)

    Flamant, Cyrille

    2017-04-01

    The EU-funded project DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa, http://www.dacciwa.eu) is investigating the relationship between weather, climate and air pollution in southern West Africa. The air over the coastal region of West Africa is a unique mixture of natural and anthropogenic gases, liquids and particles, emitted in an environment, in which multi-layer cloud decks frequently form. These exert a large influence on the local weather and climate, mainly due to their impact on radiation, the surface energy balance and thus the diurnal cycle of the atmospheric boundary layer. The main objective for the aircraft detachment was to build robust statistics of cloud properties in southern West Africa in different chemical landscapes to investigate the physical processes involved in their life cycle in such a complex chemical environment. As part of the DACCIWA field campaigns, three European aircraft (the German DLR Falcon 20, the French SAFIRE ATR 42 and the British BAS Twin Otter) conducted a total of 50 research flights across Ivory Coast, Ghana, Togo, and Benin from 27 June to 16 July 2016 for a total of 155 flight hours, including hours sponsored through 3 EUFAR projects. The aircraft were used in different ways based on their strengths, but all three had comparable instrumentation with the the capability to do gas-phase chemistry, aerosol and clouds, thereby generating a rich dataset of atmospheric conditions across the region. Eight types of flight objectives were conducted to achieve the goals of the DACCIWA: (i) Stratus clouds, (ii) Land-sea breeze clouds, (iii) Mid-level clouds, (iv) Biogenic emission, (v) City emissions, (vi) Flaring and ship emissions, (vii) Dust and biomass burning aerosols, and (viii) air-sea interactions. An overview of the DACCIWA aircraft campaign as well as first highlights from the airborne observations will be presented.

  6. Challenges for Cloud Modeling in the Context of Aerosol–Cloud–Precipitation Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Lebo, Zachary J. [Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming; Shipway, Ben J. [Met Office, Exeter, United Kingdom; Fan, Jiwen [Pacific Northwest National Laboratory, Richland, Washington; Geresdi, Istvan [Faculty of Science, University of Pécs, Pécs, Hungary; Hill, Adrian [Met Office, Exeter, United Kingdom; Miltenberger, Annette [School of Earth and Environment, University of Leeds, Leeds, United Kingdom; Morrison, Hugh [Mesoscale and Microscale Meteorology Laboratory, National Center for Atmospheric Research, Boulder, Colorado; Rosenberg, Phil [School of Earth and Environment, University of Leeds, Leeds, United Kingdom; Varble, Adam [Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah; Xue, Lulin [Research Applications Laboratory, National Center for Atmospheric Research, Boulder, Colorado

    2017-08-01

    The International Cloud Modeling Workshop (CMW) has been a longstanding tradition in the cloud microphysics modeling community and is typically held the week prior to the International Conference on Clouds and Precipitation (ICCP). For the Ninth CMW, more than 40 participants from 10 countries convened at the Met Office in Exeter, United Kingdom. The workshop included 4 detailed case studies (described in more detail below) rooted in recent field campaigns. The overarching objective of these cases was to utilize new observations to better understand inter-model differences and model deficiencies, explore new modeling techniques, and gain physical insight into the behavior of clouds. As was the case at the Eighth CMW, there was a general theme of understanding the role of aerosol impacts in the context of cloud-precipitation interactions. However, an additional objective was the focal point of several cases at the most recent workshop: microphysical-dynamical interactions. Many of the cases focused less on idealized small-domain simulations (as was the general focus of previous workshops) and more on large-scale nested configurations examining effects at various scales.

  7. PhotoCloud: Interactive remote exploration of joint 2D and 3D datasets.

    Science.gov (United States)

    Brivio, Paolo; Benedetti, Luca; Tarini, Marco; Ponchio, Federico; Cignoni, Paolo; Scopigno, Roberto

    2013-01-01

    PhotoCloud is a real-time client-server system for interactive visualization and exploration of large datasets comprising thousands of calibrated 2D photographs of a scene and a complex 3D description of the scene. The system isn't tailored to any specific data acquisition process; it aims at generality and flexibility. PhotoCloud achieves scalability through a multiresolution dynamic hierarchical representation of the data, which is remotely stored and accessed by the client through an efficient cache system. The system includes a compact image browser and a multiresolution model renderer. PhotoCloud employs iconic visualization of the images in the 3D space and projects images onto the 3D scene on the fly. Users can navigate the 2D and 3D spaces with smooth, integrated, seamless transitions between them. A study with differently skilled users confirms PhotoCloud's effectiveness and communication power. The Web extras at http://www.youtube.com/playlist?list=PLHJB2bhmgB7cmYD0ST9CEDMRv1JlX4xPH are videos demonstrating PhotoCloud, a real-time client-server system for interactive exploration of large datasets comprising 2D photos and 3D models.

  8. Ascension Island: The Layered Atlantic Smoke Interactions with Clouds (LASIC) Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Nitschke, Kim [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-30

    The ARM Climate Research Facility, a DOE scientific user facility, provides the climate research community with strategically located in situ and remote sensing observatories designed to improve the understanding and representation, in climate and earth system models, of clouds and aerosols as well as their interactions and coupling with the Earth’s surface.

  9. Power Quality of Grid-Connected Wind Turbines with DFIG and Their Interaction with the Grid

    DEFF Research Database (Denmark)

    Sun, Tao

    -control schemes. The pitch control scheme is employed to regulate the aerodynamic power from the turbine. The performances of the control schemes, respectively current control loops, power control loops, DC-link voltage control loop and pitch control loop, are illustrated, which meet the design requirements......Institutional and governmental support on wind energy sources, together with the wind energy potential and improvement of wind energy conversion technology, has led to a fast development of wind power generation in recent years. The continuous increase of the wind power penetration level brings...... a result that wind power generation gradually becomes an important component of power generation in the grid, which makes the study on the wind power quality issues and the interaction between the wind turbines and the grid necessary and imperative. The research documented in this thesis examines power...

  10. Advanced Fluid--Structure Interaction Techniques in Application to Horizontal and Vertical Axis Wind Turbines

    Science.gov (United States)

    Korobenko, Artem

    During the last several decades engineers and scientists put significant effort into developing reliable and efficient wind turbines. As a wind power production demands grow, the wind energy research and development need to be enhanced with high-precision methods and tools. These include time-dependent, full-scale, complex-geometry advanced computational simulations at large-scale. Those, computational analysis of wind turbines, including fluid-structure interaction simulations (FSI) at full scale is important for accurate and reliable modeling, as well as blade failure prediction and design optimization. In current dissertation the FSI framework is applied to most challenging class of problems, such as large scale horizontal axis wind turbines and vertical axis wind turbines. The governing equations for aerodynamics and structural mechanics together with coupled formulation are explained in details. The simulations are performed for different wind turbine designs, operational conditions and validated against field-test and wind tunnel experimental data.

  11. Wind Regimes above and below a Temperate Deciduous Forest Canopy in Complex Terrain: Interactions between Slope and Valley Winds

    Directory of Open Access Journals (Sweden)

    Xingchang Wang

    2014-12-01

    Full Text Available The thermally driven wind over mountainous terrains challenges the estimation of CO2 exchange between forests and the atmosphere when using the eddy covariance technique. In this study, the wind regimes were investigated in a temperate deciduous forested valley at the Maoershan site, Northeast China. The wind direction above the canopy was preferentially up-valley in the daytime and down-valley in the nighttime, corresponding to the diurnal patterns of above-canopy temperature gradient and stability parameter. In both leaf-on and -off nighttime, a down-valley flow with a maximum velocity of 1~3 m∙s−1 was often developed at 42 m above the ground (2.3-fold of the canopy height. However, the below-canopy prevailing wind was down-slope in the night, contrast to the below-canopy temperature lapse and unstable conditions. This substantial directional shear illustrated shallow slope winds were superimposed on larger-scale valley winds. As a consequence, the valley-wind component becomes stronger with increasing height, indicating a clear confluence of drainage flow to the valley center. In the daytime, the below-canopy wind was predominated down-slope due to the temperature inversion and stable conditions in the leaf-on season, and was mainly up-valley or down-slope in the leaf-off season. The isolation of momentum flux and radiation by the dense canopy played a key role in the formation of the below-canopy unaligned wind and inverse stability. Significant lateral kinematic momentum fluxes were detected due to the directional shear. These findings suggested a significant interaction between slope and valley winds at this site. The frequent vertical convergence / divergence above the canopy and horizontal divergence/convergence below the canopy in the nighttime / daytime is likely to induce significant advections of trace gases and energy flux.

  12. Using AMR to Simulate the 3-D Hydrodynamic Interaction of Supernova Shocks with Interstellar Gas Clouds

    Science.gov (United States)

    Orlando, S.; Peres, G.; Reale, F.; Plewa, T.; Rosner, R.; Siegel, A.

    We study the 3-D hydrodynamic interaction of supernova shock fronts with interstellar clouds to investigate the evolution, the morphology and the deviations from equilibrium of ionization. To this end, we use the FLASH code including PARAMESH, an advanced and versatile parallel adaptive mesh refinement package. We present here the preliminary results obtained modeling a representative case of a Mach 50 shock impacting on an isolated cloud with density contrast chi = 10 with respect to the ambient medium. The preliminary analysis of the non-equilibrium ionization (NEI) effects on the ionization stages of oxygen, and iron is discussed.

  13. A Star Formation/ISM Astronomical Database

    Science.gov (United States)

    Molinari, Sergio; Ali, Babar; Good, John; Noriega-Crespo, Alberto

    2003-02-01

    The Star Formation/ISM Astronomical Database (hereafter SFD) will be a set of on-line services adding value to existing data archives and published journals, along the lines of the very successful NASA/IPAC Extragalactic Database (NED) and SIMBAD projects but with a focus on star formation an the interstellar medium (ISM) within the Milky Way. Unlike NED and SIMBAD, however, the SFD must deal with multi-wavelength measurements of extended regions and cross-correlative relationships between disparate measurements. The SFD will rely heavily on existing databases, primarily adding data content and connectivity between datasets around the world, and custom tailoring of existing tools to provide interfaces (programming API, Web, and JAVA GUI) specific to this application. We consider the SFD as a valuable component in the broader context of a future Virtual Observatory.

  14. ISME and the Twilight of History

    OpenAIRE

    Lorenzo Bianconi

    2016-01-01

    In addition to the International Musicological Society there exists an International Society for Music Education, an association (affiliated with UNESCO) that gathers music educators from over 80 countries. Between the end of the last century and the beginning of the present one, the ISME issued three main policy papers: “Declaration of Beliefs for Worldwide Promotion of Music Education” (1994-96); “Policy on Music Education” (2002); and “Vision and Mission: Leading and Supporting Music Educa...

  15. Cloud condensation nuclei over the Southern Ocean: wind dependence and seasonal cycles

    Science.gov (United States)

    Gras, John L.; Keywood, Melita

    2017-04-01

    Multi-decadal observations of aerosol microphysical properties from regionally representative sites can be used to challenge regional or global numerical models that simulate atmospheric aerosol. Presented here is an analysis of multi-decadal observations at Cape Grim (Australia) that characterise production and removal of the background marine aerosol in the Southern Ocean marine boundary layer (MBL) on both short-term weather-related and underlying seasonal scales.A trimodal aerosol distribution comprises Aitken nuclei ( 350 nm) modes, with the Aitken mode dominating number concentration. Whilst the integrated particle number in the MBL over the clean Southern Ocean is only weakly dependent on wind speed, the different modes in the aerosol size distribution vary in their relationship with wind speed. The balance between a positive wind dependence in the coarse mode and negative dependence in the accumulation/CCN mode leads to a relatively flat wind dependence in summer and moderately strong positive wind dependence in winter. The changeover in wind dependence of these two modes occurs in a very small size range at the mode intersection, indicative of differences in the balance of production and removal in the coarse and accumulation/CCN modes.Whilst a marine biological source of reduced sulfur appears to dominate CCN concentration over the summer months (December to February), other components contribute to CCN over the full annual cycle. Wind-generated coarse-mode sea salt is an important CCN component year round and is the second-most-important contributor to CCN from autumn through to mid-spring (March to November). A portion of the non-seasonally dependent contributor to CCN can clearly be attributed to wind-generated sea salt, with the remaining part potentially being attributed to long-range-transported material. Under conditions of greater supersaturation, as expected in more convective cyclonic systems and their associated fronts, Aitken mode particles

  16. Improvement of Representation of the Cloud-Aerosol Interaction in Large-Scale Models

    Energy Technology Data Exchange (ETDEWEB)

    Khain, Alexander [Hebrew Univ. of Jerusalem (Israel); Phillips, Vaughan [Lund Univ. (Sweden); Pinsky, Mark [Hebrew Univ. of Jerusalem (Israel); Lynn, Barry [Hebrew Univ. of Jerusalem (Israel)

    2016-12-20

    The main achievements reached under the DOE award DE-SC0006788 are described. It is shown that the plan of the Project is completed. Unique results concerning cloud-aerosol interaction are obtained. It is shown that aerosols affect intensity of hurricanes. The effects of small aerosols on formation of ice in anvils of deep convective clouds are discovered, for the first time the mechanisms of drizzle formation are found and described quantitatively. Mechanisms of formation of warm rain are clarified and the dominating role of adiabatic processes and turbulence are stressed. Important results concerning the effects of sea spray on intensity of clouds and tropical cyclones are obtained. A novel methods of calculation of hail formation has been developed and implemented.

  17. Numerical Simulation of Tower Rotor Interaction for Downwind Wind Turbine

    Directory of Open Access Journals (Sweden)

    Isam Janajreh

    2010-01-01

    Full Text Available Downwind wind turbines have lower upwind rotor misalignment, and thus lower turning moment and self-steered advantage over the upwind configuration. In this paper, numerical simulation to the downwind turbine is conducted to investigate the interaction between the tower and the blade during the intrinsic passage of the rotor in the wake of the tower. The moving rotor has been accounted for via ALE formulation of the incompressible, unsteady, turbulent Navier-Stokes equations. The localized CP, CL, and CD are computed and compared to undisturbed flow evaluated by Panel method. The time history of the CP, aerodynamic forces (CL and CD, as well as moments were evaluated for three cross-sectional tower; asymmetrical airfoil (NACA0012 having four times the rotor's chord length, and two circular cross-sections having four and two chords lengths of the rotor's chord. 5%, 17%, and 57% reductions of the aerodynamic lift forces during the blade passage in the wake of the symmetrical airfoil tower, small circular cross-section tower and large circular cross-section tower were observed, respectively. The pronounced reduction, however, is confined to a short time/distance of three rotor chords. A net forward impulsive force is also observed on the tower due to the high speed rotor motion.

  18. Slow ions in plasma wind tunnels. [satellite-ionosphere interaction

    Science.gov (United States)

    Oran, W. A.; Stone, N. H.; Samir, U.

    1976-01-01

    One of the limitations of simulation experiments for the study of interaction between a satellite and its space environment is the background of slow ions in the plasma chamber. These ions appear to be created by charge exchange between the beam ions and residual neutral gas and may affect measurements of the current and potential in the wake. Results are presented for a plasma wind tunnel experiment to study the effect of slow ions on both the ion and electron current distribution and the electron temperature in the wake of a body in a streaming plasma. It is shown that the effect of slow ions for beam ion density not exceeding 3 is not significant for measurements of ion current variations in the wake zone. This is not the case when studies are aimed at the quantitative examination of electron current and temperature variations in the near wake zone. In these instances, the measurements of electron properties in the wake should be done at very low system pressures or over a range of system pressures in order to ascertain the influence of slow ions.

  19. A survey of solar wind conditions at 5 AU: A tool for interpreting solar wind-magnetosphere interactions at Jupiter

    Directory of Open Access Journals (Sweden)

    Robert Wilkes Ebert

    2014-09-01

    Full Text Available We examine Ulysses solar wind and interplanetary magnetic field (IMF observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1 – 4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013, Jupiter’s bow shock and magnetopause is expected to be at least 8 – 12% further from Jupiter, if these trends continue.

  20. Distribution and solar wind control of compressional solar wind-magnetic anomaly interactions observed at the Moon by ARTEMIS

    Science.gov (United States)

    Halekas, J. S.; Poppe, A. R.; Lue, C.; Farrell, W. M.; McFadden, J. P.

    2017-06-01

    A statistical investigation of 5 years of observations from the two-probe Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) mission reveals that strong compressional interactions occur infrequently at high altitudes near the ecliptic but can form in a wide range of solar wind conditions and can occur up to two lunar radii downstream from the lunar limb. The compressional events, some of which may represent small-scale collisionless shocks ("limb shocks"), occur in both steady and variable interplanetary magnetic field (IMF) conditions, with those forming in steady IMF well organized by the location of lunar remanent crustal magnetization. The events observed by ARTEMIS have similarities to ion foreshock phenomena, and those observed in variable IMF conditions may result from either local lunar interactions or distant terrestrial foreshock interactions. Observed velocity deflections associated with compressional events are always outward from the lunar wake, regardless of location and solar wind conditions. However, events for which the observed velocity deflection is parallel to the upstream motional electric field form in distinctly different solar wind conditions and locations than events with antiparallel deflections. Consideration of the momentum transfer between incoming and reflected solar wind populations helps explain the observed characteristics of the different groups of events.Plain Language SummaryWe survey the environment around the Moon to determine when and where strong amplifications in the charged particle density and magnetic field strength occur. These structures may be some of the smallest shock waves in the solar system, and learning about their formation informs us about the interaction of charged particles with small-scale magnetic fields throughout the solar system and beyond. We find that these compressions occur in an extended region downstream from the lunar dawn and dusk regions and

  1. Interactions of Mineral Dust with Clouds, Sea Surface Temperature, and Climate Modes of Variability

    Science.gov (United States)

    DeFlorio, Michael J.

    Global climate models (GCMs) are a vital tool for ensuring the prosperity and security of modern society. They allow scientists to understand complex interactions between the air, ocean, and land, and are used by policymakers to project future changes in climate on regional and global scales. The previous generation of GCMs, represented by CMIP3 models, are shown to be deficient in their representation of precipitation over the western United States, a region that depends critically on wintertime orographically enhanced precipitation for drinking water. In addition, aerosol-cloud interactions were prescribed in CMIP3 models, which decreased the value of their representation of global aerosol, cloud, and precipitation features. This has potentially large impacts on global radiation budgets, since aerosol-cloud interactions affect the spatial extent and magnitude of clouds and precipitation. The newest suite of GCMs, the Coupled Model Intercomparison Project Phase 5 (CMIP5) models, includes state-of-the-art parameterizations of small-scale features such as aerosols, clouds, and precipitation, and is widely used by the scientific community to learn more about the climate system. The Community Earth System Model (CESM), in conjunction with observations, provides several simulations to investigate the role of aerosols, clouds, and precipitation in the climate system and how they interact with larger modes of climate variability. We show that CESM produces a realistic spatial distribution of precipitation extremes over the western U.S., and that teleconnected signals of ENSO and the Pacific Decadal Oscillation to large-scale circulation patterns and precipitation over the western U.S. are improved when compared to CCSM3. We also discover a new semi-direct effect between dust and stratocumulus clouds over the subtropical North Atlantic, whereby boundary layer inversion strength increases during the most dusty summers due to shortwave absorption of dust above the planetary

  2. SHOCK-CLOUD INTERACTION AND PARTICLE ACCELERATION IN THE SOUTHWESTERN LIMB OF SN 1006

    Energy Technology Data Exchange (ETDEWEB)

    Miceli, M.; Orlando, S.; Bocchino, F. [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Acero, F. [ORAU/NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771 (United States); Dubner, G. [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); Decourchelle, A., E-mail: miceli@astropa.unipa.it [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Université Paris Diderot, CE-Saclay, F-91191 Gif-sur-Yvette (France)

    2014-02-20

    The supernova remnant SN 1006 is a powerful source of high-energy particles and evolves in a relatively tenuous and uniform environment despite interacting with an atomic cloud in its northwestern limb. The X-ray image of SN 1006 reveals an indentation in the southwestern part of the shock front and the H I maps show an isolated (southwestern) cloud, having the same velocity as the northwestern cloud, whose morphology fits perfectly in the indentation. We performed spatially resolved spectral analysis of a set of small regions in the southwestern nonthermal limb and studied the deep X-ray spectra obtained within the XMM-Newton SN 1006 Large Program. We also analyzed archive H I data, obtained by combining single-dish and interferometric observations. We found that the best-fit value of N {sub H} derived from the X-ray spectra significantly increases in regions corresponding to the southwestern cloud, while the cutoff energy of the synchrotron emission decreases. The N {sub H} variation corresponds perfectly with the H I column density of the southwestern cloud, as measured from the radio data. The decrease in the cutoff energy at the indentation clearly reveals that the back side of the cloud is actually interacting with the remnant. The southwestern limb therefore presents a unique combination of efficient particle acceleration and high ambient density, thus being the most promising region for γ-ray hadronic emission in SN 1006. We estimate that such emission will be detectable with the Fermi telescope within a few years.

  3. Speeding up CRMs for cloud-climate interaction studies by acceleration of mean state tendencies

    Science.gov (United States)

    Jones, C. R.; Bretherton, C. S.

    2014-12-01

    Cloud-resolving models (CRMs) are routinely used to simulate boundary-layer and deep convective cloud processes, aid in the development of moist physical parameterization for global models, study cloud-climate feedbacks and cloud-aerosol interaction, and as the heart of superparameterized climate models. CRMs are computationally demanding, placing practical constraints on their use in these applications, especially for long, climate-relevant simulations. In many situations, the horizontal-mean atmospheric structure evolves slowly compared to the turnover time of the most energetic turbulent eddies. We use this time scale separation to accelerate the time-integration of a CRM, the System for Atmospheric Modelling. Our approach uses a large time step to evolve the horizontally averaged state variables, followed by a short time step to calculate the turbulent fluctuations about the mean state. Using this approach, we are able to accelerate the model evolution by a factor of 8 or more in idealized stratocumulus, shallow and deep cumulus convection without substantial loss of accuracy in simulating mean cloud statistics and their sensitivity to climate change perturbations. We show how to adapt the approach to challenges arising from rapidly falling precipitation and from advecting scalars with a variety of lifetimes.

  4. Effects of Implementing Subgrid-Scale Cloud-Radiation Interactions in a Regional Climate Model

    Science.gov (United States)

    Herwehe, J. A.; Alapaty, K.; Otte, T.; Nolte, C. G.

    2012-12-01

    Interactions between atmospheric radiation, clouds, and aerosols are the most important processes that determine the climate and its variability. In regional scale models, when used at relatively coarse spatial resolutions (e.g., larger than 1 km), convective cumulus clouds need to be parameterized as subgrid-scale clouds. Like many groups, our regional climate modeling group at the EPA uses the Weather Research & Forecasting model (WRF) as a regional climate model (RCM). One of the findings from our RCM studies is that the summertime convective systems simulated by the WRF model are highly energetic, leading to excessive surface precipitation. We also found that the WRF model does not consider the interactions between convective clouds and radiation, thereby omitting an important process that drives the climate. Thus, the subgrid-scale cloudiness associated with convective clouds (from shallow cumuli to thunderstorms) does not exist and radiation passes through the atmosphere nearly unimpeded, potentially leading to overly energetic convection. This also has implications for air quality modeling systems that are dependent upon cloud properties from the WRF model, as the failure to account for subgrid-scale cloudiness can lead to problems such as the underrepresentation of aqueous chemistry processes within clouds and the overprediction of ozone from overactive photolysis. In an effort to advance the climate science of the cloud-aerosol-radiation (CAR) interactions in RCM systems, as a first step we have focused on linking the cumulus clouds with the radiation processes. To this end, our research group has implemented into WRF's Kain-Fritsch (KF) cumulus parameterization a cloudiness formulation that is widely used in global earth system models (e.g., CESM/CAM5). Estimated grid-scale cloudiness and associated condensate are adjusted to account for the subgrid clouds and then passed to WRF's Rapid Radiative Transfer Model - Global (RRTMG) radiation schemes to affect

  5. Future research directions to reconcile wind turbine - wildlife interactions

    NARCIS (Netherlands)

    May, R.; Gill, A.B.; Koppel, Johann; Langston, R.H.W.; Reichenbach, Marc; Scheidat, M.; Smallwood, Shawn; Voigt, C.; Hueppop, O.; Portman, Michelle

    2017-01-01

    Concurrent with the development of wind energy, research activity on wind energy generation and wildlife has evolved significantly during the last decade. This chapter presents an overview of remaining key knowledge gaps, consequent future research directions and their significance for management

  6. Examining In-Cloud Convective Turbulence in Relation to Total Lightning and the 3D Wind Field of Severe Thunderstorms

    Science.gov (United States)

    Al-Momar, S. A.; Deierling, W.; Williams, J. K.; Hoffman, E. G.

    2014-12-01

    Convectively induced turbulence (CIT) is commonly listed as a cause or factor in weather-related commercial aviation accidents. In-cloud CIT is generated in part by shears between convective updrafts and downdrafts. Total lightning is also dependent on a robust updraft and the resulting storm electrification. The relationship between total lightning and turbulence could prove useful in operational aviation settings with the use of future measurements from the geostationary lightning mapper (GLM) onboard the GOES-R satellite. Providing nearly hemispheric coverage of total lightning, the GLM could help identify CIT in otherwise data-sparse locations. For a severe thunderstorm case on 7 June 2012 in northeast Colorado, in-cloud eddy dissipation rate estimates from the NCAR/NEXRAD Turbulence Detection Algorithm were compared with cloud electrification data from the Colorado Lightning Mapping Array and radar products from the Denver, Colorado WSR-88D. These comparisons showed that high concentrations of very high frequency (VHF) source densities emitted by lightning occurred near and downstream of the storm's convective core. Severe turbulence was also shown to occur near this area, extending near the melting level of the storm and spreading upward and outward. Additionally, increases/decreases in VHF sources and turbulence volumes occurred within a few minutes of each other; although, light turbulence was shown to increase near one storm's dissipation. This may be due to increased shear from the now downdraft dominate storm. The 3D wind field from this case, obtained by either a dual-Doppler or a Variational Doppler Radar Assimilation System (VDRAS) analysis, will also be examined to further study the relationships between total lightning and thunderstorm kinematics. If these results prove to be robust, lightning may serve as a strong indicator of the location of moderate or greater turbulence.

  7. A new view on the solar wind interaction with the Moon

    CERN Document Server

    Bhardwaj, Anil; Alok, Abhinaw; Barabash, Stas; Wieser, Martin; Futaana, Yoshifumi; Wurz, Peter; Vorburger, Audrey; Holmström, Mats; Lue, Charles; Harada, Yuki; Asamura, Kazushi

    2015-01-01

    Characterised by a surface bound exosphere and localised crustal magnetic fields, the Moon was considered as a passive object when solar wind interacts with it. However, the neutral particle and plasma measurements around the Moon by recent dedicated lunar missions, such as Chandrayaan-1, Kaguya, Chang'E-1, LRO, and ARTEMIS, as well as IBEX have revealed a variety of phenomena around the Moon which results from the interaction with solar wind, such as backscattering of solar wind protons as energetic neutral atoms (ENA) from lunar surface, sputtering of atoms from the lunar surface, formation of a "mini-magnetosphere" around lunar magnetic anomaly regions, as well as several plasma populations around the Moon, including solar wind protons scattered from the lunar surface, from the magnetic anomalies, pick-up ions, protons in lunar wake and more. This paper provides a review of these recent findings and presents the interaction of solar wind with the Moon in a new perspective.

  8. Solar wind plasma interaction with solar probe plus spacecraft

    Directory of Open Access Journals (Sweden)

    S. Guillemant

    2012-07-01

    Full Text Available 3-D PIC (Particle In Cell simulations of spacecraft-plasma interactions in the solar wind context of the Solar Probe Plus mission are presented. The SPIS software is used to simulate a simplified probe in the near-Sun environment (at a distance of 0.044 AU or 9.5 RS from the Sun surface. We begin this study with a cross comparison of SPIS with another PIC code, aiming at providing the static potential structure surrounding a spacecraft in a high photoelectron environment. This paper presents then a sensitivity study using generic SPIS capabilities, investigating the role of some physical phenomena and numerical models. It confirms that in the near- sun environment, the Solar Probe Plus spacecraft would rather be negatively charged, despite the high yield of photoemission. This negative potential is explained through the dense sheath of photoelectrons and secondary electrons both emitted with low energies (2–3 eV. Due to this low energy of emission, these particles are not ejected at an infinite distance of the spacecraft and would rather surround it. As involved densities of photoelectrons can reach 106 cm−3 (compared to ambient ions and electrons densities of about 7 × 103 cm−3, those populations affect the surrounding plasma potential generating potential barriers for low energy electrons, leading to high recollection. This charging could interfere with the low energy (up to a few tens of eV plasma sensors and particle detectors, by biasing the particle distribution functions measured by the instruments. Moreover, if the spacecraft charges to large negative potentials, the problem will be more severe as low energy electrons will not be seen at all. The importance of the modelling requirements in terms of precise prediction of spacecraft potential is also discussed.

  9. Inverse modelling of cloud-aerosol interactions – Part 2: Sensitivity tests on liquid phase clouds using a Markov chain Monte Carlo based simulation approach

    Directory of Open Access Journals (Sweden)

    D. G. Partridge

    2012-03-01

    Full Text Available This paper presents a novel approach to investigate cloud-aerosol interactions by coupling a Markov chain Monte Carlo (MCMC algorithm to an adiabatic cloud parcel model. Despite the number of numerical cloud-aerosol sensitivity studies previously conducted few have used statistical analysis tools to investigate the global sensitivity of a cloud model to input aerosol physiochemical parameters. Using numerically generated cloud droplet number concentration (CDNC distributions (i.e. synthetic data as cloud observations, this inverse modelling framework is shown to successfully estimate the correct calibration parameters, and their underlying posterior probability distribution.

    The employed analysis method provides a new, integrative framework to evaluate the global sensitivity of the derived CDNC distribution to the input parameters describing the lognormal properties of the accumulation mode aerosol and the particle chemistry. To a large extent, results from prior studies are confirmed, but the present study also provides some additional insights. There is a transition in relative sensitivity from very clean marine Arctic conditions where the lognormal aerosol parameters representing the accumulation mode aerosol number concentration and mean radius and are found to be most important for determining the CDNC distribution to very polluted continental environments (aerosol concentration in the accumulation mode >1000 cm−3 where particle chemistry is more important than both number concentration and size of the accumulation mode.

    The competition and compensation between the cloud model input parameters illustrates that if the soluble mass fraction is reduced, the aerosol number concentration, geometric standard deviation and mean radius of the accumulation mode must increase in order to achieve the same CDNC distribution.

    This study demonstrates that inverse modelling provides a flexible, transparent and

  10. Brahan Project High Frequency Radar Ocean Measurements: Currents, Winds, Waves and Their Interactions

    Directory of Open Access Journals (Sweden)

    Belinda Lipa

    2014-12-01

    Full Text Available We describe radar measurements of waves, currents and winds made on the coast of northern Scotland during two 2013/14 winter storms, giving methods, results and interpretation. Wave parameters (height, period, direction and short-wave/wind direction were derived and compared with measurements made by a neighboring buoy and local weather stations. Wind direction and current velocity maps were produced and the interactions of winds and currents discussed. Significant oscillations in wave parameters were observed, which appear to be due to forcing by tidal current velocity variations. The oscillations in waveheight are explained using hydrodynamic analysis and derived amplitudes are compared with radar measurements.

  11. AN INTERACTIVE WEB-BASED ANALYSIS FRAMEWORK FOR REMOTE SENSING CLOUD COMPUTING

    Directory of Open Access Journals (Sweden)

    X. Z. Wang

    2015-07-01

    Full Text Available Spatiotemporal data, especially remote sensing data, are widely used in ecological, geographical, agriculture, and military research and applications. With the development of remote sensing technology, more and more remote sensing data are accumulated and stored in the cloud. An effective way for cloud users to access and analyse these massive spatiotemporal data in the web clients becomes an urgent issue. In this paper, we proposed a new scalable, interactive and web-based cloud computing solution for massive remote sensing data analysis. We build a spatiotemporal analysis platform to provide the end-user with a safe and convenient way to access massive remote sensing data stored in the cloud. The lightweight cloud storage system used to store public data and users’ private data is constructed based on open source distributed file system. In it, massive remote sensing data are stored as public data, while the intermediate and input data are stored as private data. The elastic, scalable, and flexible cloud computing environment is built using Docker, which is a technology of open-source lightweight cloud computing container in the Linux operating system. In the Docker container, open-source software such as IPython, NumPy, GDAL, and Grass GIS etc., are deployed. Users can write scripts in the IPython Notebook web page through the web browser to process data, and the scripts will be submitted to IPython kernel to be executed. By comparing the performance of remote sensing data analysis tasks executed in Docker container, KVM virtual machines and physical machines respectively, we can conclude that the cloud computing environment built by Docker makes the greatest use of the host system resources, and can handle more concurrent spatial-temporal computing tasks. Docker technology provides resource isolation mechanism in aspects of IO, CPU, and memory etc., which offers security guarantee when processing remote sensing data in the IPython Notebook

  12. Coarse-Grain QoS-Aware Dynamic Instance Provisioning for Interactive Workload in the Cloud

    Directory of Open Access Journals (Sweden)

    Jianxiong Wan

    2014-01-01

    Full Text Available Cloud computing paradigm renders the Internet service providers (ISPs with a new approach to deliver their service with less cost. ISPs can rent virtual machines from the Infrastructure-as-a-Service (IaaS provided by the cloud rather than purchasing them. In addition, commercial cloud providers (CPs offer diverse VM instance rental services in various time granularities, which provide another opportunity for ISPs to reduce cost. We investigate a Coarse-grain QoS-aware Dynamic Instance Provisioning (CDIP problem for interactive workload in the cloud from the perspective of ISPs. We formulate the CDIP problem as an optimization problem where the objective is to minimize the VM instance rental cost and the constraint is the percentile delay bound. Since the Internet traffic shows a strong self-similar property, it is hard to get an analytical form of the percentile delay constraint. To address this issue, we purpose a lookup table structure together with a learning algorithm to estimate the performance of the instance provisioning policy. This approach is further extended with two function approximations to enhance the scalability of the learning algorithm. We also present an efficient dynamic instance provisioning algorithm, which takes full advantage of the rental service diversity, to determine the instance rental policy. Extensive simulations are conducted to validate the effectiveness of the proposed algorithms.

  13. Interaction of the interplanetary shock and tangential discontinuity in the solar wind

    Science.gov (United States)

    Goncharov, Oleksandr; Koval, Andriy; Safrankova, Jana; Nemecek, Zdenek; Prech, Lubomir; Szabo, Adam; Zastenker, Georgy N.

    2017-04-01

    Collisionless shocks play a significant role in the solar wind interaction with the Earth. Fast forward interplanetary (IP) shocks driven by coronal mass ejections or by interaction of fast and slow solar wind streams can be encountered in the interplanetary space, while the bow shock is a standing fast reverse shock formed by the interaction of the supersonic solar wind with Earth's magnetic field. Both types of shocks are responsible for a transformation of a part of the energy of the directed solar wind motion to plasma heating and to acceleration of reflected particles to high energies. It is well known that the interaction of tangential discontinuities with the bow shock can create hot flow anomalies but interactions between IP shocks and tangential discontinuities in the solar wind are studied to a lesser extent due to lack of observations. A fortunate position of many spacecraft (Wind, ACE, DSCOVR, THEMIS, Spektr-R) on June 22, 2015 allows us detailed observations of an IP shock modification due to this interaction. We present an analysis of the event supported with MHD modeling that reveals basic features of the observed IP shock ramp splitting. However, a good matching of modeling and observations was found for DSCOVR and Spektr-R located above the ecliptic plane, whereas a timing of observations below this plane demonstrates problems of modeling of highly inclined discontinuities.

  14. Enhancement of wind energy harvesting by interaction between vortex-induced vibration and galloping

    Science.gov (United States)

    He, Xuefeng; Yang, Xiaokang; Jiang, Senlin

    2018-01-01

    Most wind energy harvesters (WEHs) that have been reported in the literature collect wind energy using only one type of wind-induced vibration, such as vortex-induced vibration (VIV), galloping, and flutter or wake galloping. In this letter, the interaction between VIV and galloping is used to improve the performance of WEHs. For a WEH constructed by attaching a bluff body with a rectangular cross-section to the free end of a piezoelectric cantilever, the measures to realize the interaction are theoretically discussed. Experiments verified the theoretical prediction that the WEHs with the same piezoelectric beam may demonstrate either separate or interactive VIV and galloping, depending on the geometries of the bluff bodies. For the WEHs with the interaction, the wind speed region of the VIV merges with that of the galloping to form a single region with high electrical outputs, which greatly increases the electrical outputs at low wind speeds. The interaction can be realized even when the predicted galloping critical speed is much higher than the predicted VIV critical speed. The proposed interaction is thus an effective approach to improve the scavenging efficiencies of WEHs operating at low wind speeds.

  15. Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Fast, J. D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Berg, L. K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Burleyson, C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fan, J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Feng, Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hagos, S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Huang, M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guenther, A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Laskin, A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ovchinnikov, M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shilling, J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shrivastava, M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Xiao, H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zaveri, R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zelenyuk-Imre, A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kuang, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wang, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Smith, J. [University of California-Irvine; Turner, D. [National Severe Storms Laboratory; Gentine, P. [Columbia Univ., New York, NY (United States)

    2017-05-01

    Cumulus convection is an important component in the atmospheric radiation budget and hydrologic cycle over the southern Great Plains and over many regions of the world, particularly during the summertime growing season when intense turbulence induced by surface radiation couples the land surface to clouds. Current convective cloud parameterizations contain uncertainties resulting in part from insufficient coincident data that couples cloud macrophysical and microphysical properties to inhomogeneities in land surface, boundary layer, and aerosol properties. The Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign was designed to provide a detailed set of measurements that are needed to obtain a more complete understanding of the lifecycle of shallow clouds by coupling cloud macrophysical and microphysical properties to land surface properties, ecosystems, and aerosols. Some of the land-atmosphere-cloud interactions that can be studied using HI-SCALE data are shown in Figure 1. HI-SCALE consisted of two 4-week intensive operation periods (IOPs), one in the spring (April 24-May 21) and the other in the late summer (August 28-September 24) of 2016, to take advantage of different stages of the plant lifecycle, the distribution of “greenness” for various types of vegetation in the vicinity of the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains (SGP) site, and aerosol properties that vary during the growing season. As expected, satellite measurements indicated that the Normalized Difference Vegetation Index (NDVI) was much “greener” in the vicinity of the SGP site during the spring IOP than the late summer IOP as a result of winter wheat maturing in the spring and being harvested in the early summer. As shown in Figure 2, temperatures were cooler than average and soil moisture was high during the spring IOP, while temperatures were warmer than average and

  16. Impacts of aerosol-cloud interactions on past and future changes in tropospheric composition

    Energy Technology Data Exchange (ETDEWEB)

    Unger, N.; Menon, S.; Shindell, D. T.; Koch, D. M.

    2009-02-02

    The development of effective emissions control policies that are beneficial to both climate and air quality requires a detailed understanding of all the feedbacks in the atmospheric composition and climate system. We perform sensitivity studies with a global atmospheric composition-climate model to assess the impact of aerosols on tropospheric chemistry through their modification on clouds, aerosol-cloud interactions (ACI). The model includes coupling between both tropospheric gas-phase and aerosol chemistry and aerosols and liquid-phase clouds. We investigate past impacts from preindustrial (PI) to present day (PD) and future impacts from PD to 2050 (for the moderate IPCC A1B scenario) that embrace a wide spectrum of precursor emission changes and consequential ACI. The aerosol indirect effect (AIE) is estimated to be -2.0 Wm{sup -2} for PD-PI and -0.6 Wm{sup -2} for 2050-PD, at the high end of current estimates. Inclusion of ACI substantially impacts changes in global mean methane lifetime across both time periods, enhancing the past and future increases by 10% and 30%, respectively. In regions where pollution emissions increase, inclusion of ACI leads to 20% enhancements in in-cloud sulfate production and {approx}10% enhancements in sulfate wet deposition that is displaced away from the immediate source regions. The enhanced in-cloud sulfate formation leads to larger increases in surface sulfate across polluted regions ({approx}10-30%). Nitric acid wet deposition is dampened by 15-20% across the industrialized regions due to ACI allowing additional re-release of reactive nitrogen that contributes to 1-2 ppbv increases in surface ozone in outflow regions. Our model findings indicate that ACI must be considered in studies of methane trends and projections of future changes to particulate matter air quality.

  17. Numerical investigation of the wake interaction between two model wind turbines with span-wise offset

    DEFF Research Database (Denmark)

    Sarmast, Sasan; Chivaee, Hamid Sarlak; Ivanell, Stefan

    2014-01-01

    Wake interaction between two model scale wind turbines with span-wise offset is investigated numerically using Large Eddy Simulation (LES) and the results are validated against the experimental data. An actuator line technique is used for modeling the rotor. The investigated setup refers to a ser......Wake interaction between two model scale wind turbines with span-wise offset is investigated numerically using Large Eddy Simulation (LES) and the results are validated against the experimental data. An actuator line technique is used for modeling the rotor. The investigated setup refers...... to a series of experimental measurements of two model scale turbines conducted by NTNU in low speed wind tunnel in which the two wind turbines are aligned with a span-wise offset resulting in half wake interaction. Two levels of free-stream turbulence are tested, the minimum undisturbed level of about Ti ≈ 0...

  18. MESSENGER and Venus Express Observations of the Solar Wind Interaction with Venus

    Science.gov (United States)

    Slavin, James A.; Acuna, Mario H.; Anderson, Brian J.; Barabash, Stas; Benna, Mehdi; Boardsen, Scott A.; Fraenz, Markus; Gloeckler, George; Gold, Robert E.; Ho,George C.; hide

    2009-01-01

    At 23:08 UTC on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude of 338 kin during its final flyby of Venus en route to its 2011 orbit insertion at Mercury. The availability of the simultaneous Venus Express solar wind and interplanetary magnetic field measurements provides a rare opportunity to examine the influence of upstream conditions on this planet's solar wind interaction. We present MESSENGER observations of new features of the Venus - solar wind interaction including hot flow anomalies upstream of the bow shock, a flux rope in the near-tail and a two-point determination of the timescale for magnetic flux transport through this induced magnetosphere. Citation: Stavin, J. A., et al. (2009), MESSENGER and Venus Express observations of the solar wind interaction with Venus,

  19. Properties of cloud condensation nuclei (CCN in the trade wind marine boundary layer of the western North Atlantic

    Directory of Open Access Journals (Sweden)

    T. B. Kristensen

    2016-03-01

    Full Text Available Cloud optical properties in the trade winds over the eastern Caribbean Sea have been shown to be sensitive to cloud condensation nuclei (CCN concentrations. The objective of the current study was to investigate the CCN properties in the marine boundary layer (MBL in the tropical western North Atlantic, in order to assess the respective roles of inorganic sulfate, organic species, long-range transported mineral dust and sea-salt particles. Measurements were carried out in June–July 2013, on the east coast of Barbados, and included CCN number concentrations, particle number size distributions and offline analysis of sampled particulate matter (PM and sampled accumulation mode particles for an investigation of composition and mixing state with transmission electron microscopy (TEM in combination with energy-dispersive X-ray spectroscopy (EDX. During most of the campaign, significant mass concentrations of long-range transported mineral dust was present in the PM, and influence from local island sources can be ruled out. The CCN and particle number concentrations were similar to what can be expected in pristine marine environments. The hygroscopicity parameter κ was inferred, and values in the range 0.2–0.5 were found during most of the campaign, with similar values for the Aitken and the accumulation mode. The accumulation mode particles studied with TEM were dominated by non-refractory material, and concentrations of mineral dust, sea salt and soot were too small to influence the CCN properties. It is highly likely that the CCN were dominated by a mixture of sulfate species and organic compounds.

  20. Interacting Winds in Eclipsing Symbiotic Systems – The Case Study ...

    Indian Academy of Sciences (India)

    instance, Tomov & Tomova (2001) performed the U light curve of the symbiotic AG. Peg by the occultation of a .... Figure 1(a–d). Eclipse modeling for a typical quiescent symbiotic system at the four orbital phases. In fact, the typical value of the orbital velocity, close to 10 km/s, does not modify altogether hot wind velocities of ...

  1. Interaction of Accretion Shocks with Winds Kinsuk Acharya , Sandip ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. Accretion shocks are known to oscillate in presence of cool- ing processes in the disk. This oscillation may also cause quasi-periodic oscillations of black holes. In the presence of strong winds, these shocks have oscillations in vertical direction as well. We show examples of shock oscillations under the influence of ...

  2. Interacting Winds in Eclipsing Symbiotic Systems–The Case Study ...

    Indian Academy of Sciences (India)

    We report the mathematical representation of the so called eccentric eclipse model, whose numerical solutions can be used to obtain the physical parameters of a quiescent eclipsing symbiotic system. Indeed the nebular region produced by the collision of the stellar winds should be shifted to the orbital axis because of the ...

  3. Evolution Of The Cloud Field And Wind Structure Of Ntb Disturbance

    Science.gov (United States)

    Barrado-Izagirre, Naiara; Pérez-Hoyos, S.; García-Melendo, E.; Sánchez-Lavega, A.

    2009-09-01

    The banded visual aspect of cloud patterns in Jupiter hides markedly turbulent areas visible in high resolution images. The North Temperate Belt (NTB) at 21° N planetocentric latitude where the most intense Jovian jet resides (with speeds of 160 - 180 m/s) is a region of particular interest because it is known to suffer almost every 15 years an eruption or disturbance which dramatically changes its appearance. This phenomenon is known as NTB Disturbance (NTBD). The last one of such disturbances happened in 2007 and was captured by the Hubble Space Telescope and with lower resolution by the "International Outer Planet Watch” (IOPW) network [Sánchez-Lavega et al., 2008. Depth of a strong Jovian jet from a planetary-scale disturbance driven by storms, Nature 451.]. In this work we make use of these observations to characterize the morphology of the disturbed cloud field in the wake of the plumes which originated the perturbation. This is done mostly in terms of the brightness spectral distribution in order to characterize the typical spatial frequency of the perturbation and its wavy and turbulent nature. In addition we make a comparison of the jet profile in the NTB just after the disturbance ended (June 2007) with one obtained year later (July 2008). It shows that a change occurred in its anticyclonic side producing a reinforced westward jet at 17°N with a speed change of 30 m/s. Acknowledgments: This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07

  4. Harmonic Propagation and Interaction Evaluation between Small-Scale Wind Farms and Nonlinear Loads

    Directory of Open Access Journals (Sweden)

    Cheng-Xiong Mao

    2013-07-01

    Full Text Available Distributed generation is a flexible and effective way to utilize renewable energy. The dispersed generators are quite close to the load, and pose some power quality problems such as harmonic current emissions. This paper focuses on the harmonic propagation and interaction between a small-scale wind farm and nonlinear loads in the distribution grid. Firstly, by setting the wind turbines as P – Q(V nodes, the paper discusses the expanding Newton-Raphson power flow method for the wind farm. Then the generalized gamma mixture models are proposed to study the non-characteristic harmonic propagation of the wind farm, which are based on Gaussian mixture models, improved phasor clustering and generalized Gamma models. After the integration of the small-scale wind farm, harmonic emissions of nonlinear loads will become random and fluctuating due to the non-stationary wind power. Furthermore, in this paper the harmonic coupled admittance matrix model of nonlinear loads combined with a wind farm is deduced by rigorous formulas. Then the harmonic propagation and interaction between a real wind farm and nonlinear loads are analyzed by the harmonic coupled admittance matrix and generalized gamma mixture models. Finally, the proposed models and methods are verified through the corresponding simulation models in MATLAB/SIMULINK and PSCAD/EMTDC.

  5. Interplanetary Field Enhancements: The Interaction between Solar Wind and Interplanetary Dusty Plasma Released by Interplanetary Collisions

    Science.gov (United States)

    Lai, Hairong

    Interplanetary field enhancements (IFEs) are unique large-scale structures in the solar wind. During IFEs, the magnetic-field strength is significantly enhanced with little perturbation in the solar-wind plasma. Early studies showed that IFEs move at nearly the solar-wind speed and some IFEs detected at 0.72AU by Pioneer Venus Orbiter (PVO) are associated with material co-orbiting with asteroid Oljato. To explain the observed IFE features, we develop and test an IFE formation hypothesis: IFEs result from interactions between the solar wind and clouds of nanoscale charged dust particles released in interplanetary collisions. This hypothesis predicts that the magnetic field drapes and the solar wind slows down in the upstream. Meanwhile the observed IFE occurrence rate should be comparable with the detectable interplanetary collision rate. Based on this hypothesis, we can use the IFE occurrence to determine the spatial distribution and temporal variation of interplanetary objects which produce IFEs. To test the hypothesis, we perform a systematic survey of IFEs in the magnetic-field data from many spacecraft. Our datasets cover from 1970s to present and from inner than 0.3AU to outer than 5 AU. In total, more than 470 IFEs are identified and their occurrences show clustering features in both space and time. We use multi-spacecraft simultaneous observations to reconstruct the magnetic-field geometry and find that the magnetic field drapes in the upstream region. The results of a superposed epoch study show that the solar wind slows down in the upstream and there is a plasma depletion region near the IFE centers. In addition, the solar-wind slowdown and plasma depletion feature are more significant in larger IFEs. The mass contained in IFEs can be estimated by balancing the solar-wind pressure force exerted on the IFEs against the solar gravity. The solar-wind slowdown resultant from the estimated mass is consistent with the result in superposed epoch study. The

  6. Monitoring aerosol-cloud interactions at the CESAR Observatory in the Netherlands

    Science.gov (United States)

    Sarna, Karolina; Russchenberg, Herman W. J.

    2017-06-01

    The representation of aerosol-cloud interaction (ACI) processes in climate models, although long studied, still remains the source of high uncertainty. Very often there is a mismatch between the scale of observations used for ACI quantification and the ACI process itself. This can be mitigated by using the observations from ground-based remote sensing instruments. In this paper we presented a direct application of the aerosol-cloud interaction monitoring technique (ACI monitoring). ACI monitoring is based on the standardised Cloudnet data stream, which provides measurements from ground-based remote sensing instruments working in synergy. For the data set collected at the CESAR Observatory in the Netherlands we calculate ACI metrics. We specifically use attenuated backscatter coefficient (ATB) for the characterisation of the aerosol properties and cloud droplet effective radius (re) and number concentration (Nd) for the characterisation of the cloud properties. We calculate two metrics: ACIr = ln(re)/ln(ATB) and ACIN = ln(Nd)/ln(ATB). The calculated values of ACIr range from 0.001 to 0.085, which correspond to the values reported in previous studies. We also evaluated the impact of the vertical Doppler velocity and liquid water path (LWP) on ACI metrics. The values of ACIr were highest for LWP values between 60 and 105 g m-2. For higher LWP other processes, such as collision and coalescence, seem to be dominant and obscure the ACI processes. We also saw that the values of ACIr are higher when only data points located in the updraught regime are considered. The method presented in this study allow for monitoring ACI daily and further aggregating daily data into bigger data sets.

  7. Wind Magnetic Clouds for 2010-2012: Model Parameter Fittings, Associated Shock Waves, and Comparisons to Earlier Periods

    Science.gov (United States)

    Lepping, R. P.; Wu, C.-C.; Berdichevsky, D. B.; Szabo, A.

    2015-01-01

    We fitted the parameters of magnetic clouds (MCs) as identified in the Wind spacecraft data from early 2010 to the end of 2012 using the model of Lepping, Jones, and Burlaga (J. Geophys. Res. 95, 1195, 1990). The interval contains 48 MCs and 39 magnetic cloud-like (MCL) events. This work is a continuation of MC model fittings of the earlier Wind sets, including those in a recent publication, which covers 2007 to 2009. This period (2010 - 2012) mainly covers the maximum portion of Solar Cycle 24. Between the previous and current interval, we document 5.7 years of MCs observations. For this interval, the occurrence frequency of MCs markedly increased in the last third of the time. In addition, over approximately the last six years, the MC type (i.e. the profile of the magnetic-field direction within an MC, such as North-to-South, South-to-North, all South) dramatically evolved to mainly North-to-South types when compared to earlier years. Furthermore, this evolution of MC type is consistent with global solar magnetic-field changes predicted by Bothmer and Rust (Coronal Mass Ejections, 139, 1997). Model fit parameters for the MCs are listed for 2010 - 2012. For the 5.7 year interval, the observed MCs are found to be slower, weaker in estimated axial magnetic-field intensity, and shorter in duration than those of the earlier 12.3 years, yielding much lower axial magnetic-field fluxes. For about the first half of this 5.7 year period, i.e. up to the end of 2009, there were very few associated MC-driven shock waves (distinctly fewer than the long-term average of about 50 % of MCs). But since 2010, such driven shocks have increased markedly, reflecting similar statistics as the long-term averages. We estimate that 56 % of the total observed MCs have upstream shocks when the full interval of 1995 - 2012 is considered. However, only 28 % of the total number of MCLs have driven shocks over the same period. Some interplanetary shocks during the 2010 - 2012 interval are seen

  8. Modelling wave-boundary layer interaction for wind power applications

    Science.gov (United States)

    Jenkins, A. D.; Barstad, I.; Gupta, A.; Adakudlu, M.

    2012-04-01

    Marine wind power production facilities are subjected to direct and indirect effects of ocean waves. Direct effects include forces due to wave orbital motions and slamming of the water surface under breaking wave conditions, corrosion and icing due to sea spray, and the effects of wave-generated air bubbles. Indirect effects include include the influence of waves on the aerodynamic sea-surface roughness, air turbulence, the wind velocity profile, and air velocity oscillations, wave-induced currents and sediment transport. Field observations within the boundary layers from floating measurement may have to be corrected to account for biases induced as a result of wave-induced platform motions. To estimate the effect of waves on the atmospheric boundary layer we employ the WRF non-hydrostatic mesoscale atmosphere model, using the default YSU planetary boundary layer (PBL) scheme and the WAM spectral wave model, running simultaneously and coupled using the open-source coupler MCEL which can interpolate between different model grids and timesteps. The model is driven by the WRF wind velocity at 10 m above the surface. The WRF model receives from WAM updated air-sea stress fields computed from the wind input source term, and computes new fields for the Charnock parameter and marine surface aerodynamic roughness. Results from a North Atlantic and Nordic Seas simulation indicate that the two-way coupling scheme alters the 10 metre wind predicted by WRF by up to 10 per cent in comparison with a simulation using a constant Charnock parameter. The changes are greatest in developing situations with passages of fronts, moving depressions and squalls. This may be directly due to roughness length changes, or may be due to changes in the timing of front/depression/squall passages. Ongoing work includes investigating the effect of grid refinement/nesting, employing different PBL schemes, and allowing the wave field to change the direction of the total air-sea stress.

  9. Numerical investigation of interactions between marine atmospheric boundary layer and offshore wind farm

    Science.gov (United States)

    Lyu, Pin; Chen, Wenli; Li, Hui; Shen, Lian

    2017-11-01

    In recent studies, Yang, Meneveau & Shen (Physics of Fluids, 2014; Renewable Energy, 2014) developed a hybrid numerical framework for simulation of offshore wind farm. The framework consists of simulation of nonlinear surface waves using a high-order spectral method, large-eddy simulation of wind turbulence on a wave-surface-fitted curvilinear grid, and an actuator disk model for wind turbines. In the present study, several more precise wind turbine models, including the actuator line model, actuator disk model with rotation, and nacelle model, are introduced into the computation. Besides offshore wind turbines on fixed piles, the new computational framework has the capability to investigate the interaction among wind, waves, and floating wind turbines. In this study, onshore, offshore fixed pile, and offshore floating wind farms are compared in terms of flow field statistics and wind turbine power extraction rate. The authors gratefully acknowledge financial support from China Scholarship Council (No. 201606120186) and the Institute on the Environment of University of Minnesota.

  10. Impacts of ENSO events on cloud radiative effects in preindustrial conditions: Changes in cloud fraction and their dependence on interactive aerosol emissions and concentrations: IMPACT OF ENSO ON CLOUD RADIATIVE EFFECT

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yang [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Now at Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Russell, Lynn M. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Xu, Li [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Lou, Sijia [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Lamjiri, Maryam A. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Somerville, Richard C. J. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Miller, Arthur J. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Cayan, Daniel R. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; DeFlorio, Michael J. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Ghan, Steven J. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Liu, Ying [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Singh, Balwinder [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Wang, Hailong [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Yoon, Jin-Ho [Gwangju Institute of Science and Technology, Gwangju South Korea; Rasch, Philip J. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA

    2016-06-02

    Ocean in El Niño (La Niña) events, increased (decreased) wet scavenging of natural aerosols dampens more than 4–6% of variations of cloud radiative effects averaged over the tropics. In contrast, increased surface winds cause feedbacks that increase sea spray emissions that enhance the variations by 3–4% averaged over the tropics.

  11. Analyzing complex wake-terrain interactions and its implications on wind-farm performance.

    Science.gov (United States)

    Tabib, Mandar; Rasheed, Adil; Fuchs, Franz

    2016-09-01

    Rotating wind turbine blades generate complex wakes involving vortices (helical tip-vortex, root-vortex etc.).These wakes are regions of high velocity deficits and high turbulence intensities and they tend to degrade the performance of down-stream turbines. Hence, a conservative inter-turbine distance of up-to 10 times turbine diameter (10D) is sometimes used in wind-farm layout (particularly in cases of flat terrain). This ensures that wake-effects will not reduce the overall wind-farm performance, but this leads to larger land footprint for establishing a wind-farm. In-case of complex-terrain, within a short distance (say 10D) itself, the nearby terrain can rise in altitude and be high enough to influence the wake dynamics. This wake-terrain interaction can happen either (a) indirectly, through an interaction of wake (both near tip vortex and far wake large-scale vortex) with terrain induced turbulence (especially, smaller eddies generated by small ridges within the terrain) or (b) directly, by obstructing the wake-region partially or fully in its flow-path. Hence, enhanced understanding of wake- development due to wake-terrain interaction will help in wind farm design. To this end the current study involves: (1) understanding the numerics for successful simulation of vortices, (2) understanding fundamental vortex-terrain interaction mechanism through studies devoted to interaction of a single vortex with different terrains, (3) relating influence of vortex-terrain interactions to performance of a wind-farm by studying a multi-turbine wind-farm layout under different terrains. The results on interaction of terrain and vortex has shown a much faster decay of vortex for complex terrain compared to a flatter-terrain. The potential reasons identified explaining the observation are (a) formation of secondary vortices in flow and its interaction with the primary vortex and (b) enhanced vorticity diffusion due to increased terrain-induced turbulence. The implications of

  12. Implementation of aerosol-cloud interactions in the regional atmosphere-aerosol model COSMO-MUSCAT(5.0) and evaluation using satellite data

    Science.gov (United States)

    Dipu, Sudhakar; Quaas, Johannes; Wolke, Ralf; Stoll, Jens; Mühlbauer, Andreas; Sourdeval, Odran; Salzmann, Marc; Heinold, Bernd; Tegen, Ina

    2017-06-01

    The regional atmospheric model Consortium for Small-scale Modeling (COSMO) coupled to the Multi-Scale Chemistry Aerosol Transport model (MUSCAT) is extended in this work to represent aerosol-cloud interactions. Previously, only one-way interactions (scavenging of aerosol and in-cloud chemistry) and aerosol-radiation interactions were included in this model. The new version allows for a microphysical aerosol effect on clouds. For this, we use the optional two-moment cloud microphysical scheme in COSMO and the online-computed aerosol information for cloud condensation nuclei concentrations (Cccn), replacing the constant Cccn profile. In the radiation scheme, we have implemented a droplet-size-dependent cloud optical depth, allowing now for aerosol-cloud-radiation interactions. To evaluate the models with satellite data, the Cloud Feedback Model Intercomparison Project Observation Simulator Package (COSP) has been implemented. A case study has been carried out to understand the effects of the modifications, where the modified modeling system is applied over the European domain with a horizontal resolution of 0.25° × 0.25°. To reduce the complexity in aerosol-cloud interactions, only warm-phase clouds are considered. We found that the online-coupled aerosol introduces significant changes for some cloud microphysical properties. The cloud effective radius shows an increase of 9.5 %, and the cloud droplet number concentration is reduced by 21.5 %.

  13. Aerodynamic Interactions between Pairs of Vertical-Axis Wind Turbines

    Science.gov (United States)

    Brownstein, Ian; Dabiri, John

    2017-11-01

    Increased power production has been observed in downstream vertical-axis wind turbines (VAWTs) when positioned offset from the wake of upstream turbines. This effect was found to exist in both laboratory and field environments with pairs of co- and counter-rotating turbines. It is hypothesized that the observed power production enhancement is due to flow acceleration adjacent to the upstream turbine caused by bluff body blockage, which increases the incident freestream velocity on appropriately positioned downstream turbines. This type of flow acceleration has been observed in computational and laboratory studies of VAWTs and will be further investigated here using 3D-PTV measurements around pairs of laboratory-scale VAWTs. These measurements will be used to understand the mechanisms behind the performance enhancement effect and seek to determine optimal separation distances and angles between turbines based on turbine design parameters. These results will lead to recommendations for optimizing the power production of VAWT wind farms which utilize this effect.

  14. The Generation and Assimilation of Cloud-Drift Winds in Numerical Weather Prediction (gtSpecial IssueltData Assimilation in Meteology and Oceanography: Theory and Practice)

    OpenAIRE

    John F. Le, Marshall; Lance M., Leslie; Connie, Spinoso; Bureau of Meteorology Research Centre; School of Mathematics, University of New South Wales; Department of Land Information, RMIT

    1997-01-01

    This paper describes the methods used to produce cloud-drift winds (CDWs), concentrating, in particular, on their generation from sequential Geostationary Meteorological Satellite (GMS) imagery. It discusses the estimation of these motion vectors from both infrared (IR) and visible imagery at high spatial and temporal resolution and also records their accuracy and utility. The paper then discusses the assimilation of CDW data for numerical weather prediction (NWP). It does this by looking at ...

  15. Effects of wake-turbine blade interactions on power production of wind turbines

    Science.gov (United States)

    Tadokoro, Maki; Yokoyama, Hiroshi; Iida, Akiyoshi

    2017-01-01

    In offshore wind farms, deterioration in power generation performance due to the mutual interference of flow around the wind turbines is a serious issue. To clarify the effects of wake-turbine blade interactions on the performance of wind farms, we conducted large-scale simulations of the flow around two full-scale wind turbines in a tandem-arrangement with two different spacings. The spacing between the two turbines was L/D = 1.0 and L/D = 2.0, with D being the rotor diameter. The predicted results show that vortices generated in the wake of the first turbine interfere with the blades of the second turbine and the interference becomes more intense for the case of L/D = 1.0. Thus, the power coefficient of the downstream turbine becomes lower by 80% for the case of L/D = 1.0 compared with the case of a single wind turbine.

  16. CloudSat observations of cloud-type distribution over the Indian summer monsoon region

    Directory of Open Access Journals (Sweden)

    K. V. Subrahmanyam

    2013-07-01

    Full Text Available The three-dimensional distribution of various cloud types over the Indian summer monsoon (ISM region using five years (2006–2010 of CloudSat observations during June-July-August-September months is discussed for the first time. As the radiative properties, latent heat released and microphysical properties of clouds differ largely depending on the cloud type, it becomes important to know what types of clouds occur over which region. In this regard, the present analysis establishes the three-dimensional distribution of frequency of occurrence of stratus (St, stratocumulus (Sc, nimbostratus (Ns, cumulus (Cu, altocumulus (Ac, altostratus (As, cirrus (Ci and deep convective (DC clouds over the ISM region. The results show that the various cloud types preferentially occur over some regions of the ISM, which are consistent during all the years of observations. It is found that the DC clouds frequently occur over northeast of Bay of Bengal (BoB, Ci clouds over a wide region of south BoB–Indian peninsula–equatorial Indian Ocean, and Sc clouds over the north Arabian Sea. Ac clouds preferentially occur over land, and a large amount of As clouds are found over BoB. The occurrence of both St and Ns clouds over the study region is much lower than all other cloud types.The interannual variability of all these clouds including their vertical distribution is discussed. It is envisaged that the present study opens up possibilities to quantify the feedback of individual cloud type in the maintenance of the ISM through radiative forcing and latent heat release.

  17. Feeding versus Falling: The Growth and Collapse of Molecular Clouds in a Turbulent Interstellar Medium

    Science.gov (United States)

    Ibáñez-Mejía, Juan C.; Mac Low, Mordecai-Mark; Klessen, Ralf S.; Baczynski, Christian

    2017-11-01

    In order to understand the origin of observed molecular cloud (MC) properties, it is critical to understand how clouds interact with their environments during their formation, growth, and collapse. It has been suggested that accretion-driven turbulence can maintain clouds in a highly turbulent state, preventing runaway collapse and explaining the observed non-thermal velocity dispersions. We present 3D, adaptive-mesh-refinement, magnetohydrodynamical simulations of a kiloparsec-scale, stratified, supernova-driven, self-gravitating, interstellar medium (ISM), including diffuse heating and radiative cooling. These simulations model the formation and evolution of a MC population in the turbulent ISM. We use zoom-in techniques to focus on the dynamics of the mass accretion and its history for individual MCs. We find that mass accretion onto MCs proceeds as a combination of turbulent flow and near free-fall accretion of a gravitationally bound envelope. Nearby supernova explosions have a dual role, compressing the envelope and increasing mass accretion rates, but also disrupting parts of the envelope and eroding mass from the cloud’s surface. It appears that the inflow rate of kinetic energy onto clouds from supernova explosions is insufficient to explain the net rate of change of the cloud kinetic energy. In the absence of self-consistent star formation, the conversion of gravitational potential into kinetic energy during contraction seems to be the main driver of non-thermal motions within clouds. We conclude that although clouds interact strongly with their environments, bound clouds are always in a state of gravitational contraction, close to runaway, and their properties are a natural result of this collapse.

  18. ISME and the Twilight of History

    Directory of Open Access Journals (Sweden)

    Lorenzo Bianconi

    2016-12-01

    Full Text Available In addition to the International Musicological Society there exists an International Society for Music Education, an association (affiliated with UNESCO that gathers music educators from over 80 countries. Between the end of the last century and the beginning of the present one, the ISME issued three main policy papers: “Declaration of Beliefs for Worldwide Promotion of Music Education” (1994-96; “Policy on Music Education” (2002; and “Vision and Mission: Leading and Supporting Music Education Worldwide” (2006. A comparative analysis of the three ‘manifestos’ reveals that, while in 1994-96 the ISME explicitly included the triad ‘history – culture – aesthetics’ in its conception, and regarded the ‘listening’ of music as an educationally significant activity, after just a few years the first and third notions (‘history,’ ‘aesthetics’ have all but vanished, and music listening has also disappeared from the agenda. The fact that the notion of ‘history’ and the aesthetic approach to musical art have disappeared from the perspective of music educators worldwide may have to do with scruples about political correctness, motivated by the “Mexico City Declaration on Cultural Policies” of UNESCO (1982, where the notion of ‘culture’ had already replaced that of ‘history’. To be sure, this ignorance, or suspicion, about the historical aspects of music production does not in any way facilitate the task of musicologists (or of ethnomusicologists, nor that of music education teachers.

  19. Aerosol-cloud interactions over major urban clusters of China using MODIS satellite data

    Science.gov (United States)

    Stathopoulos, Stavros; Kourtidis, Konstantinos; Alexandri, Georgia; Georgoulias, Aristeidis; Wang, Pucai

    2014-05-01

    Urban clusters are a prominent political and economic issue in China. Increased numbers of cities of different sizes and intensive urbanization characterize these regions, which extend over hundreds of kilometers. We study here the interactions between aerosols and clouds under different synoptic regimes over major urban clusters of China, using a decade (2003 - 2013) of MODIS observations from Terra and Aqua satellites. The relationships which are studied are mainly between the aerosol optical depth at 550 nm (AOD550) and cloud cover (CC), cloud water path (CWP) and water vapour (WV). The region of China was separated in 5 climatic zones which are primarily influenced by the Asian monsoon systems and the Tibetan Plateau. Over all urban clusters and in all seasons, CC is found to increase with AOD550. On the other hand, CWP-AOD550 and WV-AOD550 relationships appear more complicated and are discussed also in view of their impact on CC. This research has been financed by EPAN II and PEP under the national action "Bilateral, multilateral and regional R&T cooperations" (AEROVIS Sino-Greek project).

  20. A comparison of outer electron radiation belt dropouts during solar wind stream interface and magnetic cloud driven storms

    Science.gov (United States)

    Ogunjobi, O.; Sivakumar, V.; Mtumela, Z.

    2017-06-01

    Energetic electrons are trapped in the Earth's radiation belts which occupy a toroidal region between 3 and 7 \\hbox {R}E above the Earth's surface. Rapid loss of electrons from the radiation belts is known as dropouts. The source and loss mechanisms regulating the radiation belts population are not yet understood entirely, particularly during geomagnetic storm times. Nevertheless, the dominant loss mechanism may require an event based study to be better observed. Utilizing multiple data sources from the year 1997-2007, this study identifies radiation belt electron dropouts which are ultimately triggered when solar wind stream interfaces (SI) arrived at Earth, or when magnetic clouds (MC) arrived. Using superposed epoch analysis (SEA) technique, a synthesis of multiple observations is performed to reveal loss mechanism which might, perhaps, be a major contributor to radiation belt losses under SI and MC driven storms. Results show an abrupt slower decaying precipitation of electron peak (about 3000 counts/sec) on SI arrival within 5.05 < L < 6.05, which persist till 0.5 day before gradual recovery. This pattern is interpreted as an indication of depleted electrons from bounce lost cone via precipitating mechanism known as relativistic electron microburst. On the other hand, MC shows a pancake precipitating peak extending to lower L (Plasmapause); indicating a combination of electron cyclotron harmonic (ECH) and whistler mode waves as the contributing mechanisms.

  1. Solar wind interaction with small bodies. 1: Whistler wing signatures near to Gaspra and Ida

    Science.gov (United States)

    Wang, Z.; Kivelson, M. G.; Joy, S.; Khurana, K. K.; Polanskey, C.; Southwood, D. J.; Walker, R. J.

    1995-01-01

    Data from Galileo's two asteroid flybys reveal magnetic fluctuations that we interpret as perturbations of the solar wind magnetic field caused by an interaction with the nearby asteroid. The scale sizes of the bodies (approximately 14 km for Gaspra and approximately 30 km for Ida) are intermediate between the ion and electron gyroradii, which implies that the asteroid-imposed perturbations propagate in the whistler mode. Special properties of the whistler mode include phase phase velocities that can exceed the solar wind speed and confinement of the disturbance to directions nearly aligned with the magnetic field. These features of the interaction impose a structure on the solar wind disturbance that differs greatly from the forms familiar for either magnetized or unmagnetized bodies of magnetohydrodynamic spatial scales. We examine both data and computer simulations of the interaction with special attention to what can be inferred about the interaction itself from analysis of the data.

  2. Magnetic fields in the solar system planets, moons and solar wind interactions

    CERN Document Server

    Wicht, Johannes; Gilder, Stuart; Holschneider, Matthias

    2018-01-01

    This book addresses and reviews many of the still little understood questions related to the processes underlying planetary magnetic fields and their interaction with the solar wind. With focus on research carried out within the German Priority Program ”PlanetMag”, it also provides an overview of the most recent research in the field. Magnetic fields play an important role in making a planet habitable by protecting the environment from the solar wind. Without the geomagnetic field, for example, life on Earth as we know it would not be possible. And results from recent space missions to Mars and Venus strongly indicate that planetary magnetic fields play a vital role in preventing atmospheric erosion by the solar wind. However, very little is known about the underlying interaction between the solar wind and a planet’s magnetic field. The book takes a synergistic interdisciplinary approach that combines newly developed tools for data acquisition and analysis, computer simulations of planetary interiors an...

  3. Interaction between the low altitude atmosphere and clouds by high-precision polarization lidar

    Science.gov (United States)

    Shiina, Tatsuo; Noguchi, Kazuo; Fukuchi, Tetsuo

    2012-11-01

    Lidar is a powerful remote sensing tool to monitor the weather changes and the environmental issues. This technique should not been restricted in those fields. In this study, the authors aim to be apply it to the prediction of weather disaster. The heavy rain and the lightning strike are our targets. The inline typed MPL (micro pulse lidar) has been accomplished to grasp the interaction between the low altitude cloud and the atmosphere and to predict the heavy rain, while it was hard to catch the sign of lightning strike. The authors introduced a new algorism to catch the direct sign of the lightning strike. Faraday effect is caused by lightning discharge in the ionized atmosphere. This effect interacts with the polarization of the propagating beam, that is, the polarization plane is rotated by the effect. In this study, high precision polarization lidar was developed to grasp the small rotation angle of the polarization of the propagating beam. In this report, the interaction between the low altitude cloud and the atmosphere was monitored by the high precision polarization lidar. And the observation result of the lightning discharge were analyzed.

  4. Sub-Synchronous Interaction Analysis between DFIG Based Wind Farm and Series Compensated Network

    OpenAIRE

    Wang, Yun; Wu, Qiuwei; Kang, Shaoli

    2016-01-01

    This paper analyzes the sub-synchronous interaction (SSI) phenomenon between the doubly fed induction generator (DFIG) based wind farm (WF) and the series capacitor compensated network. The possible types of SSI in the DFIG based WF are studied. The factors influencing the SSI of DFIG based WF are investigated. The large signal stability and small signal stability of the DFIG based WF with different series compensation (SC) level and wind speed are simulated and compared.

  5. Effect of soil-foundation-structure interaction on the seismic response of wind turbines

    Directory of Open Access Journals (Sweden)

    Sam Austin

    2017-09-01

    Full Text Available Soil-foundation-structure interaction can affect the seismic response of wind turbines. This paper studies the effects of soil-foundation-structure interaction on the seismic response of 65 kW, 1 MW, and 2 MW horizontal-axis wind turbines with truncated cone steel towers. Four types of foundations with frequency-based design were analyzed, including spread foundation, mono pile, pile group with cap, and anchored spread foundation. Soil is modeled both implicitly (subgrade reaction modulus and explicitly. The finite element model developed using the ANSYS program was first validated using experimental data. Numerical models are then analyzed in both frequency and time domains using the Block Lanczos and generalized HHT-α formulations. Recommendations were given to simplify the soil-foundation-structure interaction analysis of wind turbines subjected to seismic loading.

  6. Euler-Lagrange Simulations of Shock Wave-Particle Cloud Interaction

    Science.gov (United States)

    Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Park, Chanyoung; Balachandar, S.

    2017-11-01

    Numerical experiments of shock interacting with an evolving and fixed cloud of particles are performed. In these simulations we use Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. As validation, we use Sandia Multiphase Shock Tube experiments and particle-resolved simulations. The particle curtain upon interaction with the shock wave is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In the simulations evolving the particle cloud, the initial volume fraction profile matches with that of Sandia Multiphase Shock Tube experiments, and the shock Mach number is limited to M =1.66. Measurements of particle dispersion are made at different initial volume fractions. A detailed analysis of the influence of initial conditions on the evolution of the particle cloudis presented. The early time behavior of the models is studied in the fixed bed simulations at varying volume fractions and shock Mach numbers.The mean gas quantities are measured in the context of 1-way and 2-way coupled simulations. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

  7. submitter ELECTRON CLOUD AND COLLECTIVE EFFECTS IN THE INTERACTION REGION OF FCC-ee

    CERN Document Server

    Belli, E; Rumolo, G

    2016-01-01

    The FCC-ee is an e⁺e⁻ circular collider designed to accommodate four different experiments in a beam energy range from 91 to 350 GeV and is a part of the Future Circular Collider (FCC) project at CERN. One of the most critical aspects of this new very challenging machine regards the collective effects which can produce instabilities, thus limiting the accelerator operation and reducing its performance. The following studies are focused on the Interaction Region of the machine. This talk will present preliminary simulation results of the power loss due to the wake fields generated by the electromagnetic interaction of the beam with the vacuum chamber. A preliminary estimation of the electron cloud build-up is also reported, whose effects have been recognized as one of the main limitations for the Large Hadron Collider at CERN.

  8. Role of Low Clouds in Summertime Atmosphere-Ocean Interactions over the North Pacific.

    Science.gov (United States)

    Norris, Joel R.; Zhang, Yuan; Wallace, John M.

    1998-10-01

    The summer-to-summer variability of the areal extent of marine stratiform cloudiness (MSC; stratus, stratocumulus, and fog) over the North Pacific is examined for the period of record 1952-92 using a dataset based on surface observations. Variability is largest in two regions: the central and western Pacific along 35°N coincident with a strong meridional gradient in climatological MSC amount, and the eastern Pacific near 15°N downstream of the persistent stratocumulus deck off Baja California. The MSC amount in both regions tends to be negatively correlated with local sea surface temperature (SST), suggestive of a positive cloud feedback on SST. The MSC amounts in the two regions also tend to be negatively correlated by virtue of their relationship to the basin-wide sea level pressure (SLP) field: a strengthening of the seasonal mean subtropical anticyclone is accompanied by increased cloudiness in the trade wind regime and decreased cloudiness in the southerly flow farther toward the west. These relationships are reflected in the leading modes derived from empirical orthogonal function analysis and singular value decomposition analysis of the MSC, SST, and SLP fields.From the 1950s to the 1980s, summertime MSC amounts increased in the central and western Pacific and decreased in the trade wind region, while SST exhibited the opposite tendencies. Although these trends contributed to the relationships described above, similar patterns are obtained when the analysis is performed on 1-yr difference fields (e.g., 1953 minus 1952, 1954 minus 1953, etc.). Hence, it appears that MSC plays an important role in atmosphere-ocean coupling over the North Pacific during the summer season when latent and sensible heat fluxes are not as dominant and the coupling between atmospheric circulation and SST is not as strong as in winter.

  9. Simulation and Prediction of Wakes and Wake Interaction in Wind Farms

    DEFF Research Database (Denmark)

    Andersen, Søren Juhl

    coupled with the flow solver. The numerical simulations include the study of the far wake behind a single turbine, three idealised cases of infinitely long rows of turbines and finally three infinite wind farm scenarios with different spacings. The flow characteristics between the turbines, turbine...... the basis for two proposed dynamic wake models of the turbulent wake deep inside large wind farms. The first model is based on a direct reconstruction using POD, while the other model (REDOMO) is based on an additional reduction by only including the most dominant frequencies. The flow fields derived from......The highly turbulent wake and the wake interaction of merging wakes between multiple wind turbines are modelled using Large Eddy Simulation (LES) in a general Navier-Stokes solver. The Actuator Line (AL) technique is employed to model the wind turbines, and the aeroelastic computations are fully...

  10. Statistical properties of aerosol-cloud-precipitation interactions in South America

    Directory of Open Access Journals (Sweden)

    T. A. Jones

    2010-03-01

    Full Text Available Given the complex interaction between aerosol, cloud, and atmospheric properties, it is difficult to extract their individual effects to observed rainfall amount. This research uses principle component analysis (PCA that combines Moderate Resolution Imaging Spectroradiometer (MODIS aerosol and cloud products, NCEP Reanalysis atmospheric products, and rainrate estimates from the Tropical Rainfall Measuring Mission (TRMM precipitation radar (PR to assess if aerosols affect warm rain processes. Data collected during September 2006 over the Amazon basin in South America during the biomass-burning season are used. The goal of this research is to combine these observations into a smaller number of variables through PCA with each new variable having a unique physical interpretation. In particular, we are concerned with PC variables whose weightings include aerosol optical thickness (AOT, as these may be an indicator of aerosol indirect effects. If they are indeed occurring, then PC values that include AOT should change as a function of rainrate.

    To emphasize the advantage of PCA, changes in aerosol, cloud, and atmospheric observations are compared to rainrate. Comparing no-rain, rain, and heavy rain only (>5 mm h−1 samples, we find that cloud thicknesses, humidity, and upward motion are all greater during rain and heavy rain conditions. However, no statistically significant difference in AOT exists between each sample, indicating that atmospheric conditions are more important to rainfall than aerosol concentrations as expected. If aerosols are affecting warm process clouds, it would be expected that stratiform precipitation would decrease as a function increasing aerosol concentration through either Twomey and/or semi-direct effects. PCA extracts the latter signal in a variable labeled PC2, which explains 15% of the total variance and is second in importance the variable (PC1 containing the broad atmospheric conditions. PC2

  11. Effects of model resolution and parameterizations on the simulations of clouds, precipitation, and their interactions with aerosols

    Science.gov (United States)

    Lee, Seoung Soo; Li, Zhanqing; Zhang, Yuwei; Yoo, Hyelim; Kim, Seungbum; Kim, Byung-Gon; Choi, Yong-Sang; Mok, Jungbin; Um, Junshik; Ock Choi, Kyoung; Dong, Danhong

    2018-01-01

    This study investigates the roles played by model resolution and microphysics parameterizations in the well-known uncertainties or errors in simulations of clouds, precipitation, and their interactions with aerosols by the numerical weather prediction (NWP) models. For this investigation, we used cloud-system-resolving model (CSRM) simulations as benchmark simulations that adopt high-resolution and full-fledged microphysical processes. These simulations were evaluated against observations, and this evaluation demonstrated that the CSRM simulations can function as benchmark simulations. Comparisons between the CSRM simulations and the simulations at the coarse resolutions that are generally adopted by current NWP models indicate that the use of coarse resolutions as in the NWP models can lower not only updrafts and other cloud variables (e.g., cloud mass, condensation, deposition, and evaporation) but also their sensitivity to increasing aerosol concentration. The parameterization of the saturation process plays an important role in the sensitivity of cloud variables to aerosol concentrations. while the parameterization of the sedimentation process has a substantial impact on how cloud variables are distributed vertically. The variation in cloud variables with resolution is much greater than what happens with varying microphysics parameterizations, which suggests that the uncertainties in the NWP simulations are associated with resolution much more than microphysics parameterizations.

  12. Long-term wave growth and its linear and nonlinear interactions with wind fluctuations

    Directory of Open Access Journals (Sweden)

    Z. Ge

    2008-05-01

    Full Text Available Following Ge and Liu (2007, the simultaneously recorded time series of wave elevation and wind velocity are examined for long-term (on Lavrenov's τ4-scale or 3 to 6 h linear and nonlinear interactions between the wind fluctuations and the wave field. Over such long times the detected interaction patterns should reveal general characteristics for the wave growth process. The time series are divided into three episodes, each approximately 1.33 h long, to represent three sequential stages of wave growth. The classic Fourier-domain spectral and bispectral analyses are used to identify the linear and quadratic interactions between the waves and the wind fluctuations as well as between different components of the wave field.

    The results show clearly that as the wave field grows the linear interaction becomes enhanced and covers wider range of frequencies. Two different wave-induced components of the wind fluctuations are identified. These components, one at around 0.4 Hz and the other at around 0.15 to 0.2 Hz, are generated and supported by both linear and quadratic wind-wave interactions probably through the distortions of the waves to the wind field. The fact that the higher-frequency wave-induced component always stays with the equilibrium range of the wave spectrum around 0.4 Hz and the lower-frequency one tends to move with the downshifting of the primary peak of the wave spectrum defines the partition of the primary peak and the equilibrium range of the wave spectrum, a characteristic that could not be revealed by short-time wavelet-based analyses in Ge and Liu (2007. Furthermore, these two wave-induced peaks of the wind spectrum appear to have different patterns of feedback to the wave field. The quadratic wave-wave interactions also are assessed using the auto-bispectrum and are found to be especially active during the first and the third episodes. Such directly detected wind-wave interactions, both linear and

  13. Condensed-phase biogenic-anthropogenic interactions with implications for cold cloud formation.

    Science.gov (United States)

    Charnawskas, Joseph C; Alpert, Peter A; Lambe, Andrew T; Berkemeier, Thomas; O'Brien, Rachel E; Massoli, Paola; Onasch, Timothy B; Shiraiwa, Manabu; Moffet, Ryan C; Gilles, Mary K; Davidovits, Paul; Worsnop, Douglas R; Knopf, Daniel A

    2017-08-24

    Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil fuel combustion can acquire a coating of SOA. We investigate SOA-soot biogenic-anthropogenic interactions and their impact on ice nucleation in relation to the particles' organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without the presence of sulfate or soot particles. Corresponding particle glass transition (Tg) and full deliquescence relative humidity (FDRH) were estimated using a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfate mixtures exhibit a core-shell configuration (i.e. a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation, in agreement with respective Tg and FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid, inducing ice nucleation. Naphthalene SOA coated soot particles acted as ice nuclei above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate renders this even less likely. However, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during pre-industrial times or in pristine areas.

  14. Oscillation mode analysis considering the interaction between a DFIG-based wind turbine and the grid

    Science.gov (United States)

    Wu, Wangping; Xie, Da; Lu, Yupu; Zhao, Zuyi; Yu, Songtao

    2017-01-01

    Sub-synchronous interactions between wind farms and transmission networks with series compensation have drawn great attention. As most large wind farms in Europe and Asia employ doubly fed induction generator turbines, there has recently been a growing interest in studying this phenomenon. To study the stability of wind turbine with doubly fed induction generator after a small disturbance, a complete small signal system is built in this paper. By using eigenvalue and participation factor analysis, the relation between the modes and state variables can be discovered. Thereafter, the oscillation modes are classified into electrical resonance, sub-synchronous resonance, sub-synchronous oscillation, sub-synchronous control interaction, and low frequency oscillation. To verify the oscillation frequency of each oscillation mode, time-domain simulation based on MATLAB/Simulink is presented. The simulation results justify the effectiveness of the small-signal models.

  15. Importance of air-sea interaction on wind waves, storm surge and hurricane simulations

    Science.gov (United States)

    Chen, Yingjian; Yu, Xiping

    2017-04-01

    It was reported from field observations that wind stress coefficient levels off and even decreases when the wind speed exceeds 30-40 m/s. We propose a wave boundary layer model (WBLM) based on the momentum and energy conservation equations. Taking into account the physical details of the air-sea interaction process as well as the energy dissipation due to the presence of sea spray, this model successfully predicts the decreasing tendency of wind stress coefficient. Then WBLM is embedded in the current-wave coupled model FVCOM-SWAVE to simulate surface waves and storm surge under the forcing of hurricane Katrina. Numerical results based on WBLM agree well with the observed data of NDBC buoys and tide gauges. Sensitivity analysis of different wind stress evaluation methods also shows that large anomalies of significant wave height and surge elevation are captured along the passage of hurricane core. The differences of the local wave height are up to 13 m, which is in accordance with the general knowledge that the ocean dynamic processes under storm conditions are very sensitive to the amount of momentum exchange at the air-sea interface. In the final part of the research, the reduced wind stress coefficient is tested in the numerical forecast of hurricane Katrina. A parabolic formula fitted to WBLM is employed in the atmosphere-ocean coupled model COAWST. Considering the joint effects of ocean cooling and reduced wind drag, the intensity metrics - the minimum sea level pressure and the maximum 10 m wind speed - are in good inconsistency with the best track result. Those methods, which predict the wind stress coefficient that increase or saturate in extreme wind condition, underestimate the hurricane intensity. As a whole, we unify the evaluation methods of wind stress in different numerical models and yield reasonable results. Although it is too early to conclude that WBLM is totally applicable or the drag coefficient does decrease for high wind speed, our current

  16. The DACCIWA project: Dynamics-aerosol-chemistry-cloud interactions in West Africa

    Science.gov (United States)

    Knippertz, Peter

    2017-04-01

    This contribution provides an overview of the EU-funded DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) project. DACCIWA consists of 16 European and African research organisations and has strong links to universities, weather services and government organisations across West Africa. The project runs from 2010 to 2018 and is built around a major international field campaign in 2016. A key motivation for DACCIWA is the expected tripling of anthropogenic emissions in southern West Africa (SWA) between 2000 and 2030, whose impacts on human health, ecosystems, food security and the regional climate are largely unknown. An integrated assessment of this problem, which is mostly due to massive economic and population growth and urbanization, is challenging due to (a) a superposition of regional effects with global climate change, (b) a strong dependence on the variable West African monsoon, (c) incomplete scientific understanding of interactions between emissions, clouds, radiation, precipitation and regional circulations, and (d) a lack of observations. DACCIWA combines measurements in the field in SWA with extensive modelling activities and work on satellite data. In particular during the main DACCIWA field campaign in June-July 2016 high-quality observations of emissions, atmospheric composition and meteorological parameters were sampled. The campaign involved three research aircraft, three ground-based supersites, enhanced radiosonde launches, and intensive measurements at urban sites in Abidjan and Cotonou. These data have already been quality-controlled and will be freely available to the research community through a database at http://baobab.sedoo.fr/DACCIWA/ after the end of the project. The resulting benchmark dataset is currently combined with a wide range of modelling and satellite-based research activities that will ultimately allow (a) an assessment of the roles of relevant physical, chemical and biological processes, (b) an improvement

  17. Cloud-based interactive analytics for terabytes of genomic variants data.

    Science.gov (United States)

    Pan, Cuiping; McInnes, Gregory; Deflaux, Nicole; Snyder, Michael; Bingham, Jonathan; Datta, Somalee; Tsao, Philip S

    2017-12-01

    Large scale genomic sequencing is now widely used to decipher questions in diverse realms such as biological function, human diseases, evolution, ecosystems, and agriculture. With the quantity and diversity these data harbor, a robust and scalable data handling and analysis solution is desired. We present interactive analytics using a cloud-based columnar database built on Dremel to perform information compression, comprehensive quality controls, and biological information retrieval in large volumes of genomic data. We demonstrate such Big Data computing paradigms can provide orders of magnitude faster turnaround for common genomic analyses, transforming long-running batch jobs submitted via a Linux shell into questions that can be asked from a web browser in seconds. Using this method, we assessed a study population of 475 deeply sequenced human genomes for genomic call rate, genotype and allele frequency distribution, variant density across the genome, and pharmacogenomic information. Our analysis framework is implemented in Google Cloud Platform and BigQuery. Codes are available at https://github.com/StanfordBioinformatics/mvp_aaa_codelabs. cuiping@stanford.edu or ptsao@stanford.edu. Supplementary data are available at Bioinformatics online.

  18. Interaction between Seabed Soil and Offshore Wind Turbine Foundations

    DEFF Research Database (Denmark)

    Hansen, Nilas Mandrup

    design recommendations. The present study addresses the pile/seabed interaction problem, related to the stiffness of the monopile by means of a numerical model and experimental investigations. The numerical model is a 3D model. COMSOL Multiphysics, a finiteelement software, is used to calculate the soil...

  19. Happiness in Economics as Understood Across Ism and Religion

    Directory of Open Access Journals (Sweden)

    Abdul Ghafar Ismail

    2014-12-01

    Full Text Available The concept of happiness has been discussed long time ago by economists. Recently, it became the most related and important thing to be studied because of its impact in societies. Discussion about happiness basically interprets within two separate views. First, happiness related with economic variable, for instance, how money can create happiness. Second happiness is discussed within the context of religion. However, the discussion did not combine both contexts, economic variable and religion, to interpret happiness. Therefore, it is important to highlight the concept of happiness in a different way such as in this article. Different cultures will have their own perspective on the determination of happiness. From just “individual perspective” of happiness, they then formed an ism through involvement of a big society from the same culture. Some isms such as hedonism and materialism are synonyms in characterizing the concept of happiness in this modern world. At the same time, the isms are actually working with the economic and non-economic indicators as elements to strengthen the ism itself. On the other hand, the concept of happiness from the perspective of religion will also be a part of discussion in this article. Therefore, this article will reveal that the meaning of happiness is different in terms of religion and ism. So, to carry out both ism and religion simultaneously in shaping a more intrinsic value of happiness is not an easy task. Furthermore, religion is always associated with spiritual value that makes it hard for some people to practice religion and their isms at the same time. Thus, this article will propose that the right interpretation of isms based on their faith in religion can contribute to the concept of genuine happiness.

  20. Sub-Synchronous Interaction Analysis between DFIG Based Wind Farm and Series Compensated Network

    DEFF Research Database (Denmark)

    Wang, Yun; Wu, Qiuwei; Kang, Shaoli

    2016-01-01

    This paper analyzes the sub-synchronous interaction (SSI) phenomenon between the doubly fed induction generator (DFIG) based wind farm (WF) and the series capacitor compensated network. The possible types of SSI in the DFIG based WF are studied. The factors influencing the SSI of DFIG based WF...

  1. An MHD Study of the Interaction Between the Solar Wind and the Interstellar Medium

    Science.gov (United States)

    Steinolfson, R. S.

    1996-01-01

    The overall objective of this research program is to obtain a better understanding of the interaction between the solar wind and the interstellar medium through the use of numerical solutions of the time-dependent magnetohydrodynamic (MHD) equations. The simulated results have been compared with observations where possible and with the results from previous analytic and numerical studies. The primary accomplishment of this project has been the development of codes for 2-D models in both spherical and cylindrical coordinates and the application of the codes to the solar wind/interstellar medium interaction. Computations have been carried out for both a relatively simple gas-dynamic interaction and a flow-aligned interstellar magnetic field. The results have been shown to compare favorably with models that use more approximations and to modify and extend the previous results as would be expected. The simulations have also been used along with a data analysis study to provide a quantitative estimate of the distance to the termination and bow shocks. Some of the specific topics that have been studied are: (1) gas dynamic models of the solar wind/interstellar medium interaction, (2) termination shock response to large-scale solar wind fluctuations, and (3) distances to the termination shock and heliopause. The main results from each of these studies are summarized. The results were published in three papers which are included as attachments.

  2. Numerical simulations of wake interaction between two wind turbines at various inflow conditions

    DEFF Research Database (Denmark)

    Troldborg, Niels; Larsen, Gunner Chr.; Aagaard Madsen, Helge

    2011-01-01

    The phenomenon of wake interaction between two wind turbines was analysed using the actuator line technique and full unsteady Navier–Stokes computations. Results are presented for varying mutual distances between the two turbines and both full wake and half wake situations were considered...

  3. Kelvin-Helmholtz instability at the magnetopause and the solar wind-magnetosphere interaction

    Energy Technology Data Exchange (ETDEWEB)

    Ziemkiewicz-Dabrowska, J.

    1980-01-01

    The literature dealing with instability caused by inhomogeneous mass flow is briefly reviewed. The Kelvin-Helmholtz instability is investigated on the basis of MHD and CGL equations, with allowance for the effects of the finite Larmor radius of the ions. Results relating to the problem of magnetopause stability and the possibility of viscous interaction at the solar wind-magnetosphere boundary are presented.

  4. Hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil

    Directory of Open Access Journals (Sweden)

    THIAGO R. RODRIGUES

    Full Text Available ABSTRACT Matter and energy flux dynamics of wetlands are important to understand environmental processes that govern biosphere-atmosphere interactions across ecosystems. This study presents analyses about hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil. This study was conducted in Private Reserve of Natural Heritage (PRNH SESC, 16º39'50''S; 56º47'50''W in Brazilian Wetland. According to Curado et al. (2012, the wet season occurs between the months of January and April, while the June to September time period is the dry season. Results presented same patterns in energies fluxes in all period studied. Wind speed and air temperature presented same patterns, while LE was relative humidity presented inverse patterns of the air temperature. LE was predominant in all seasons and the sum of LE and H was above 90% of net radiation. Analyses of linear regression presented positive interactions between wind speed and LE, and wind speed and H in all seasons, except in dry season of 2010. Confidence coefficient regression analyses present statistical significance in all wet and dry seasons, except dry season of 2010, suggest that LE and H had interaction with other micrometeorological variables.

  5. Aerosol and cloud microphysics covariability in the northeast Pacific boundary layer estimated with ship-based and satellite remote sensing observations: NE Pacific Aerosol-Cloud Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Painemal, David [Science Systems and Applications, Inc., Hampton Virginia USA; NASA Langley Research Center, Hampton Virginia USA; Chiu, J. -Y. Christine [Department of Meteorology, University of Reading, Reading UK; Minnis, Patrick [NASA Langley Research Center, Hampton Virginia USA; Yost, Christopher [Science Systems and Applications, Inc., Hampton Virginia USA; Zhou, Xiaoli [Department of Atmospheric and Oceanic Sciences, McGill University, Montreal Quebec Canada; Cadeddu, Maria [Environmental Science Division, Argonne National Laboratory, Lemont Illinois USA; Eloranta, Edwin [Space Science and Engineering Center, University of Wisconsin-Madison, Madison Wisconsin USA; Lewis, Ernie R. [Brookhaven National Laboratory, Upton New York USA; Ferrare, Richard [NASA Langley Research Center, Hampton Virginia USA; Kollias, Pavlos [School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook New York USA

    2017-02-27

    Ship measurements collected over the northeast Pacific along transects between the port of Los Angeles (33.7°N, 118.2°W) and Honolulu (21.3°N, 157.8°W) during May to August 2013 were utilized to investigate the covariability between marine low cloud microphysical and aerosol properties. Ship-based retrievals of cloud optical depth (τ) from a Sun photometer and liquid water path (LWP) from a microwave radiometer were combined to derive cloud droplet number concentration Nd and compute a cloud-aerosol interaction (ACI) metric defined as ACICCN = ∂ ln(Nd)/∂ ln(CCN), with CCN denoting the cloud condensation nuclei concentration measured at 0.4% (CCN0.4) and 0.3% (CCN0.3) supersaturation. Analysis of CCN0.4, accumulation mode aerosol concentration (Na), and extinction coefficient (σext) indicates that Na and σext can be used as CCN0.4 proxies for estimating ACI. ACICCN derived from 10 min averaged Nd and CCN0.4 and CCN0.3, and CCN0.4 regressions using Na and σext, produce high ACICCN: near 1.0, that is, a fractional change in aerosols is associated with an equivalent fractional change in Nd. ACICCN computed in deep boundary layers was small (ACICCN = 0.60), indicating that surface aerosol measurements inadequately represent the aerosol variability below clouds. Satellite cloud retrievals from MODerate-resolution Imaging Spectroradiometer and GOES-15 data were compared against ship-based retrievals and further analyzed to compute a satellite-based ACICCN. Satellite data correlated well with their ship-based counterparts with linear correlation coefficients equal to or greater than 0.78. Combined satellite Nd and ship-based CCN0.4 and Na yielded a maximum ACICCN = 0.88–0.92, a value slightly less than the ship-based ACICCN, but still consistent with aircraft-based studies in the eastern Pacific.

  6. Interaction of plasma cloud with external electric field in lower ionosphere

    Directory of Open Access Journals (Sweden)

    Y. S. Dimant

    2010-03-01

    Full Text Available In the auroral lower-E and upper-D region of the ionosphere, plasma clouds, such as sporadic-E layers and meteor plasma trails, occur daily. Large-scale electric fields, created by the magnetospheric dynamo, will polarize these highly conducting clouds, redistributing the electrostatic potential and generating anisotropic currents both within and around the cloud. Using a simplified model of the cloud and the background ionosphere, we develop the first self-consistent three-dimensional analytical theory of these phenomena. For dense clouds, this theory predicts highly amplified electric fields around the cloud, along with strong currents collected from the ionosphere and circulated through the cloud. This has implications for the generation of plasma instabilities, electron heating, and global MHD modeling of magnetosphere-ionosphere coupling via modifications of conductances induced by sporadic-E clouds.

  7. Cloud management and security

    CERN Document Server

    Abbadi, Imad M

    2014-01-01

    Written by an expert with over 15 years' experience in the field, this book establishes the foundations of Cloud computing, building an in-depth and diverse understanding of the technologies behind Cloud computing. In this book, the author begins with an introduction to Cloud computing, presenting fundamental concepts such as analyzing Cloud definitions, Cloud evolution, Cloud services, Cloud deployment types and highlighting the main challenges. Following on from the introduction, the book is divided into three parts: Cloud management, Cloud security, and practical examples. Part one presents the main components constituting the Cloud and federated Cloud infrastructure(e.g., interactions and deployment), discusses management platforms (resources and services), identifies and analyzes the main properties of the Cloud infrastructure, and presents Cloud automated management services: virtual and application resource management services. Part two analyzes the problem of establishing trustworthy Cloud, discuss...

  8. THE LAUNCHING OF COLD CLOUDS BY GALAXY OUTFLOWS. I. HYDRODYNAMIC INTERACTIONS WITH RADIATIVE COOLING

    Energy Technology Data Exchange (ETDEWEB)

    Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States); Brüggen, Marcus [Universität Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg (Germany)

    2015-06-01

    To better understand the nature of the multiphase material found in outflowing galaxies, we study the evolution of cold clouds embedded in flows of hot and fast material. Using a suite of adaptive mesh refinement simulations that include radiative cooling, we investigate both cloud mass loss and cloud acceleration under the full range of conditions observed in galaxy outflows. The simulations are designed to track the cloud center of mass, enabling us to study the cloud evolution at long disruption times. For supersonic flows, a Mach cone forms around the cloud, which damps the Kelvin–Helmholtz instability but also establishes a streamwise pressure gradient that stretches the cloud apart. If time is expressed in units of the cloud crushing time, both the cloud lifetime and the cloud acceleration rate are independent of cloud radius, and we find simple scalings for these quantities as a function of the Mach number of the external medium. A resolution study suggests that our simulations accurately describe the evolution of cold clouds in the absence of thermal conduction and magnetic fields, physical processes whose roles will be studied in forthcoming papers.

  9. Gamma rays from clumpy wind-jet interactions in high-mass microquasars

    Science.gov (United States)

    de la Cita, V. M.; del Palacio, S.; Bosch-Ramon, V.; Paredes-Fortuny, X.; Romero, G. E.; Khangulyan, D.

    2017-07-01

    Context. The stellar winds of the massive stars in high-mass microquasars are thought to be inhomogeneous. The interaction of these inhomogeneities, or clumps, with the jets of these objects may be a major factor in gamma-ray production. Aims: Our goal is to characterize a typical scenario of clump-jet interaction, and calculate the contribution of these interactions to the gamma-ray emission from these systems. Methods: We use axisymmetric, relativistic hydrodynamical simulations to model the emitting flow in a typical clump-jet interaction. Using the simulation results we perform a numerical calculation of the high-energy emission from one of these interactions. The radiative calculations are performed for relativistic electrons locally accelerated at the jet shock, and the synchrotron and inverse Compton radiation spectra are computed for different stages of the shocked clump evolution. We also explore different parameter values, such as viewing angle and magnetic field strength. The results derived from one clump-jet interaction are generalized phenomenologically to multiple interactions under different wind models, estimating the clump-jet interaction rates, and the resulting luminosities in the GeV range. Results: If particles are efficiently accelerated in clump-jet interactions, the apparent gamma-ray luminosity through inverse Compton scattering with the stellar photons can be significant even for rather strong magnetic fields and thus efficient synchrotron cooling. Moreover, despite the standing nature or slow motion of the jet shocks for most of the interaction stage, Doppler boosting in the postshock flow is relevant even for mildly relativistic jets. Conclusions: For clump-to-average wind density contrasts greater than or equal to ten, clump-jet interactions could be bright enough to match the observed GeV luminosity in Cyg X-1 and Cyg X-3 when a jet is present in these sources, with required non-thermal-to-total available power fractions greater than

  10. Soil structure interaction in offshore wind turbine collisions

    DEFF Research Database (Denmark)

    Samsonovs, Artjoms; Giuliani, Luisa; Zania, Varvara

    2014-01-01

    after a ship collision, thus providing an insight on the consequences of a collision event and on the main aspects to be considered when designing for this load case. In particular, the role of the foundation soil properties (site conditions) on the response of the structural system is investigated....... Dynamic finite element analyses have been performed taking into account the geometric and material nonlinearity of the tower, and the effects of soil structure interaction (SSI) have been studied in two representative collision scenarios of a service vessel with the turbine: a moderate energy impact...

  11. A GIS-based interactive web decision support system for planning wind farms in Tuscany (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Mari, Riccardo; Bottai, Lorenzo; Busillo, Caterina [Laboratory of Monitoring and Environmental Modelling for the sustainable development (LAMMA), Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Calastrini, Francesca; Gozzini, Bernardo; Gualtieri, Giovanni [Research National Council-Institute for biometeorology (CNR-IBIMET), Via Caproni 8, 50145 Firenze (Italy)

    2011-02-15

    In the framework of regional renewable energy policies, starting from 2008 the Tuscany Regional Authority promoted the ''WIND-GIS'' project aimed at assessing the large-scale wind potential of Tuscany region, Italy. This goal was achieved by developing an integrated Geographic Information System (GIS) based decision support system (DSS), compliant with Directive 2007/2/EC of European Commission (EC), which was designed to help public operators in the preliminary location of sites eligible for wind harness. To make the system an actually operative tool, it was conceived as a web-oriented interactive system that the public operators may freely access. The DSS was developed by using the MapServer open-source web-GIS application. Furthermore, the ''p.mapper'' front-end application developed in JavaScript and PHP/Mapscript was used, which enables a user-friendly interface to MapServer to be performed. System's wind resource data are estimated by the 2-km resolution application over Tuscany of a meteorological model chain through a 4-year period (January 2004-December 2007) with a 1-h time-step. Wind estimations at 75 m were taken into account in order to be addressed to large-scale wind turbines according to the Tuscany Energy Plan objectives of 300 MW installed power derived from wind within 2012. Furthermore, to overcome the problems posed by all groups involved with initially opposing positions in the location for new wind farms (e.g., investors vs. environmentalist groups), the DSS also encompasses a number of layers such as landscape, ecological and archaeological constrained areas. This paper presents the description of the DSS, as well as the application results in terms of maps of wind resource and energy yield once a 2-MW wind turbine has been set as a sample. The developed DSS is currently in use by the Tuscany Regional Authority for planning the regional wind energy strategy. (author)

  12. 3D, multi-fluid, MHD calculations of Mars interaction with the solar wind

    Science.gov (United States)

    Najib, D.; Toth, G.; Nagy, A. F.; Curry, S.; Ma, Y.

    2010-12-01

    We use our 3D multi-fluid MHD model to simulate the interaction of the solar wind with non-magnetized planets, Mars in particular. We set the lower boundary to 100 km and consider photo and electron impact ionization as well as charge exchange in our chemistry. We also add more realistic physical processes to our model, and test it against different solar wind conditions. In addition, we are solving for the electron pressure and therefore for the electron fluid. We also calculate the escape fluxes and compare our results to observations.

  13. Climate Response to Warm Cloud-Aerosol Interactions: Comparisons With Direct Aerosol and Long-Lived Greenhouse Gas Impacts

    Science.gov (United States)

    Ramaswamy, V.; Ming, Y.

    2006-12-01

    We employ the NOAA/ GFDL global atmospheric model coupled to a mixed-layer ocean to investigate the mechanisms and quantitative aspects underlying the radiative perturbations and climate response arising due to cloud-aerosol interactions in low-lying clouds. The aerosol species considered include sulfate, sea-salt and carbonaceous species, whose space-time distributions are determined offline by the MOZART 2 chemistry- transport model based on emissions data. The model's prognostic cloud scheme of liquid water and amount is expanded to include cloud droplet concentration in a way that importantly allows them to be computed using the same large-scale and convective updraft velocity field. The equilibrium response of the model's global climate system to the change in aerosols from pre- industrial to present-day is evaluated, in terms of the forcing applied and the role of the large- and cloud-scale feedback mechanisms. The cloud characteristics simulated are compared against observations, while the model's response is compared with that obtained from using a diagnostic aerosol-cloud relationship to highlight the significance of specific cloud microphysical processes. The spatial distributions of the thermal and hydrologic responses are also compared with those resulting from simulations performed for the pre-industrial to present-day direct aerosol effect. The temperature responses in the low and high latitudes, including changes in the large-scale precipitation pattern, are contrasted with those due to the well-mixed greenhouse gases. The forcing-response relationship is examined for the radiative perturbations investigated, with surface radiative forcing included in these considerations. We finally investigate the concept of linear additivity of the responses in various climate variables for the set of radiative perturbations considered above, extending from the global- and zonal-mean to continental scales.

  14. Beyond the Flipped Classroom: A Highly Interactive Cloud-Classroom (HIC) Embedded into Basic Materials Science Courses

    Science.gov (United States)

    Liou, Wei-Kai; Bhagat, Kaushal Kumar; Chang, Chun-Yen

    2016-01-01

    The present study compares the highly interactive cloud-classroom (HIC) system with traditional methods of teaching materials science that utilize crystal structure picture or real crystal structure model, in order to examine its learning effectiveness across three dimensions: knowledge, comprehension and application. The aim of this study was to…

  15. Sheath-limited unipolar induction in the solar wind. [plasma interactions with solar system bodies

    Science.gov (United States)

    Srnka, L. J.

    1975-01-01

    A model of the steady-state interaction between the solar wind and an electrically conducting body having neither an atmosphere nor an intrinsic magnetic field sufficient enough to deflect the plasma flow is presented which considers some effects of a plasma surface sheath on unipolar induction. The Sonett-Colburn (1967, 1968) unipolar dynamo model is reviewed, and it is noted that the unipolar dynamo response of an electrically conducting body in the solar wind's motional field can be controlled by sheath effects in certain cases where the body radius is less than a certain critical value. It is shown that sheath effects do not limit the unipolar response of the moon or Mercury since their body radii are much larger than their critical radii. Sheath effects are also considered for asteroids, the Martian satellites, the irregular Jovian satellites, the outer satellites of Saturn, and meteorite parent bodies in a primordial enhanced solar wind.

  16. Advanced Visualization and Interactive Display Rapid Innovation and Discovery Evaluation Research (VISRIDER) Program Task 6: Point Cloud Visualization Techniques for Desktop and Web Platforms

    Science.gov (United States)

    2017-04-01

    ADVANCED VISUALIZATION AND INTERACTIVE DISPLAY RAPID INNOVATION AND DISCOVERY EVALUATION RESEARCH (VISRIDER) PROGRAM TASK 6: POINT CLOUD...To) OCT 2013 – SEP 2014 4. TITLE AND SUBTITLE ADVANCED VISUALIZATION AND INTERACTIVE DISPLAY RAPID INNOVATION AND DISCOVERY EVALUATION RESEARCH

  17. Wind turbine generator interaction with diesel generators on an isolated power system

    Energy Technology Data Exchange (ETDEWEB)

    Scott, G.W.; Wilreker, V.F.

    1984-05-01

    The Block Island Power Company (BIPCO), on Block Island, Rhode Island, operates an isolated electric power system consisting of diesel generation and an experimental wind turbine. The 150-kW wind turbine, designated MOD-OA by the U.S. Department of Energy is typically operated in parallel with two diesel generators to serve an average winter load of 350 kW. As part of an experimental program to evaluate wind turbine generator performance on the isolated diesel power system, the recordings from an extensive data measurement effort were reviewed and analyzed to define the nature of the dynamic interaction effects. The data were collected over a three-month period on the system to which the DOE/NASA experimental wind turbine was connected. During this time, the diesel units were lightly loaded resulting in up to 60% of the total load demand being supplied by the MOD-OA in periods of severely gusting winds. In three of the modes of normal MOD-OA operation -- startup synchronization, shutdown/cutout, and continuous fixed pitch running -power, frequency and voltage transients were comparable with those produced by typical load changes on the diesel system alone. In the fourth mode, variable pitch (constant power) control, a significant reduction in system damping sometimes occurred which gave rise to increased frequency and voltage perturbations under gusty wind conditions. Based on a linear model of the system it is shown that changes in control system settings could be made to improve damping. The main study conclusion is that wind turbine generation, even when providing a large portion of the power required by an isolated utility, can be a practical option resulting in system disturbances no greater than those found in conventional diesel systems.

  18. Interaction between Water and Wind as a Driver of Passive Dispersal in Mangroves

    Science.gov (United States)

    Van der Stocken, Tom; Vanschoenwinkel, Bram; De Ryck, Dennis J. R.; Bouma, Tjeerd J.; Dahdouh-Guebas, Farid; Koedam, Nico

    2015-01-01

    Although knowledge on dispersal patterns is essential for predicting long-term population dynamics, critical information on the modalities of passive dispersal and potential interactions between vectors is often missing. Here, we use mangrove propagules with a wide variety of morphologies to investigate the interaction between water and wind as a driver of passive dispersal. We imposed 16 combinations of wind and hydrodynamic conditions in a flume tank, using propagules of six important mangrove species (and genera), resulting in a set of dispersal morphologies that covers most variation present in mangrove propagules worldwide. Additionally, we discussed the broader implications of the outcome of this flume study on the potential of long distance dispersal for mangrove propagules in nature, applying a conceptual model to a natural mangrove system in Gazi Bay (Kenya). Overall, the effect of wind on dispersal depended on propagule density (g l-1). The low-density Heritiera littoralis propagules were most affected by wind, while the high-density vertically floating propagules of Ceriops tagal and Bruguiera gymnorrhiza were least affected. Avicennia marina, and horizontally floating Rhizophora mucronata and C. tagal propagules behaved similarly. Morphological propagule traits, such as the dorsal sail of H. littoralis, explained another part of the interspecific differences. Within species, differences in dispersal velocities can be explained by differences in density and for H. littoralis also by variations in the shape of the dorsal sail. Our conceptual model illustrates that different propagule types have a different likelihood of reaching the open ocean depending on prevailing water and wind currents. Results suggest that in open water, propagule traits (density, morphology, and floating orientation) appear to determine the effect of water and wind currents on dispersal dynamics. This has important implications for inter- and intraspecific variation in dispersal

  19. First highlights of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) field campaigns

    Science.gov (United States)

    Liousse, C.; Knippertz, P.; Flamant, C.; Adon, J.; Akpo, A.; Annesi-Maesano, I.; Assamoi, E.; Baeza, A.; Julien, B.; Bedou, M.; Brooks, B. J.; Chiu, J. Y. C.; Chiron, C.; Coe, H.; Danuor, S.; Djossou, J.; Evans, M. J.; Fayomi, B.; Fink, A. H.; Galy-Lacaux, C.; Gardrat, E.; Jegede, O.; Kalthoff, N.; Kedote, M.; Keita, S.; Kouame, K.; Konare, A.; Leon, J. F.; Mari, C. H.; Lohou, F.; Roblou, L.; Schlager, H.; Schwarzenboeck, A.; Toure, E. N.; Veronique, Y.

    2016-12-01

    The EU-funded project DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) is investigating the relationship between weather, climate, air pollution and health in southern West Africa. The air over the coastal region of West Africa is a unique mixture of natural and anthropogenic gases, liquids and particles, emitted in an environment, in which multi-layer cloud decks frequently form. These exert a large influence on the local weather and climate, which has never been studied in detail over West Africa: this information is currently not included in the majority of weather and climate models. For the first time, the entire chain of impacts of natural and manmade emissions on the West African atmosphere was investigated in a coordinated field campaign. As part of this campaign, three research aircraft (Falcon 20, Twin Otter and ATR) based in Lomé (Togo) flew targeted 50 missions over West Africa from 27 June to 16 July 2016. In that campaign also, three highly instrumented measuring sites inland were set up with weather balloons launched several times a day across the region. The main objective was to build robust statistics of cloud properties in southern West Africa in different chemical landscapes (background state, ship/flaring emissions, polluted megacities, agricultural and forest areas, dust from the Sahel/Sahara). In addition, DACCIWA scientists working on measurements of urban emissions, air pollution, and health have set up four urban sites in Abidjan (Cote d'Ivoire) and Cotonou (Benin) focusing on main specific regional combustion sources (domestic fires, traffic and waste burning). Long-term measurements of gases and particles and census of hospital admissions for respiratory diseases were started in January 2015 and will continue until March 2017 to determine the links between human health and air pollution. Intensive measurement periods took place in July 2015, January 2016, and July 2016 (a final one is planned for January 2017) in

  20. Neutral ISM, Ly α , and Lyman-continuum in the Nearby Starburst Haro 11

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Thorsen, T. Emil; Östlin, Göran; Hayes, Matthew; Puschnig, Johannes, E-mail: trive@astro.su.se [Department of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden)

    2017-03-01

    Star-forming galaxies are believed to be a major source of Lyman continuum (LyC) radiation responsible for reionizing the early universe. Direct observations of escaping ionizing radiation have however been sparse and with low escape fractions. In the local universe, only 10 emitters have been observed, with typical escape fractions of a few percent. The mechanisms regulating this escape need to be strongly evolving with redshift in order to account for the epoch of reionization. Gas content and star formation feedback are among the main suspects, known to both regulate neutral gas coverage and evolve with cosmic time. In this paper, we reanalyze Hubble Space Telescope ( HST )-Cosmic Origins Spectrograph (COS) spectrocopy of the first detected local LyC leaker, Haro 11. We examine the connection between LyC leakage and Ly α line shape, and feedback-influenced neutral interstellar medium (ISM) properties like kinematics and gas distribution. We discuss the two extremes of an optically thin, density bounded ISM and a riddled, optically thick, ionization bounded ISM, and how Haro 11 fits into theoretical predictions. We find that the most likely ISM model is a clumpy neutral medium embedded in a highly ionized medium with a combined covering fraction of unity and a residual neutral gas column density in the ionized medium high enough to be optically thick to Ly α , but low enough to be at least partly transparent to LyC and undetected in Si ii. This suggests that star formation feedback and galaxy-scale interaction events play a major role in opening passageways for ionizing radiation through the neutral medium.

  1. Wind Structure and Wind Loading

    DEFF Research Database (Denmark)

    Brorsen, Michael

    The purpose of this note is to provide a short description of wind, i.e. of the flow in the atmosphere of the Earth and the loading caused by wind on structures. The description comprises: causes to the generation of windhe interaction between wind and the surface of the Earthhe stochastic nature...... of windhe interaction between wind and structures, where it is shown that wind loading depends strongly on this interaction...

  2. Interactions between wind and tidally induced currents in coastal and shelf basins

    Science.gov (United States)

    Jacob, Benjamin; Stanev, Emil Vassilev

    2017-10-01

    This paper addresses the impact of atmospheric variability on ocean circulation in tidal and non-tidal basins. The data are generated by an unstructured-grid numerical model resolving the dynamics in the coastal area, as well as in the straits connecting the North Sea and Baltic Sea. The model response to atmospheric forcing in different frequency intervals is quantified. The results demonstrate that the effects of the two mechanical drivers, tides and wind, are not additive, yet non-linear interactions play an important role. There is a tendency for tidally and wind-driven circulations to be coupled, in particular in the coastal areas and straits. High-frequency atmospheric variability tends to amplify the mean circulation and modify the exchange between the North and the Baltic Sea. The ocean response to different frequency ranges in the wind forcing is area-selective depending on specific local dynamics. The work done by wind on the oceanic circulation depends strongly upon whether the regional circulation is tidally or predominantly wind-driven. It has been demonstrated that the atmospheric variability affects the spring-neap variability very strongly.

  3. Hybrid Simulations of the Interaction Between Solar Wind Flow and the Hermean Magnetosphere

    Science.gov (United States)

    Travnicek, P.; Hellinger, P.; Schriver, D.; Ashour-Abdalla, M.

    2003-12-01

    We examine the magnetosphere of Mercury using global three dimensional hybrid plasma simulations. Hybrid simulations treat ions as particles and electrons as a fluid. Having ions as particles allows ion kinetic behavior and waves to be included in the physical treatment of the plasma as compared to magnetohydrodynamic (MHD) modeling that treats the plasma as a single magnetized fluid and does not include such kinetic effects. Kinetic effects are essential for understanding magnetospheric physics. Hybrid simulations scale to the ion inertial length and thus on a global scale are somewhat limited in spatial extent compared to an MHD simulation. We note effects caused by the scalling of the numerical model of the magnetized obstacle interacting with the solar wind flow with the full scale simulation. Hermean magnetosphere is estimated to be only a few times the planetary radius, it can fit within a hybrid simulation system. The overal structure of the interaction between a magnetized obstacle in the solar wind flow is determined by few basic parameters (namely the solar wind density, background magnetic field, and the speed of solar wind, and also the strength of the magnetic dipole of the obstacle and its radius). The structure of the interaction of the solar wind flow with Mercury is to a large extend unique when compared to other planets. For example, the magnetic moment of the Mercury is over 1000 times smaller than that of the Earth and also the solar wind is stronger nearby Mercury than at Earth's vicinity. The typical magnetosperic scales are comparable to the ion gyroradii and hence kinetic effects are important for the overall structure of the interaction between the Hermean magnetospere and the solar wind. In this paper we shall focus on the study of the overal structure of the bow shock and magnetosheath of Mercury. We shall examine the formation of the magnetospheric tail. We shall study particle distribution functions in different locations of the

  4. Real-time 3-D hybrid simulation of Titan's plasma interaction during a solar wind excursion

    Directory of Open Access Journals (Sweden)

    S. Simon

    2009-09-01

    Full Text Available The plasma environment of Saturn's largest satellite Titan is known to be highly variable. Since Titan's orbit is located within the outer magnetosphere of Saturn, the moon can leave the region dominated by the magnetic field of its parent body in times of high solar wind dynamic pressure and interact with the thermalized magnetosheath plasma or even with the unshocked solar wind. By applying a three-dimensional hybrid simulation code (kinetic description of ions, fluid electrons, we study in real-time the transition that Titan's plasma environment undergoes when the moon leaves Saturn's magnetosphere and enters the supermagnetosonic solar wind. In the simulation, the transition between both plasma regimes is mimicked by a reversal of the magnetic field direction as well as a change in the composition and temperature of the impinging plasma flow. When the satellite enters the solar wind, the magnetic draping pattern in its vicinity is reconfigured due to reconnection, with the characteristic time scale of this process being determined by the convection of the field lines in the undisturbed plasma flow at the flanks of the interaction region. The build-up of a bow shock ahead of Titan takes place on a typical time scale of a few minutes as well. We also analyze the erosion of the newly formed shock front upstream of Titan that commences when the moon re-enters the submagnetosonic plasma regime of Saturn's magnetosphere. Although the model presented here is far from governing the full complexity of Titan's plasma interaction during a solar wind excursion, the simulation provides important insights into general plasma-physical processes associated with such a disruptive change of the upstream flow conditions.

  5. Wind-US Code Contributions to the First AIAA Shock Boundary Layer Interaction Prediction Workshop

    Science.gov (United States)

    Georgiadis, Nicholas J.; Vyas, Manan A.; Yoder, Dennis A.

    2013-01-01

    This report discusses the computations of a set of shock wave/turbulent boundary layer interaction (SWTBLI) test cases using the Wind-US code, as part of the 2010 American Institute of Aeronautics and Astronautics (AIAA) shock/boundary layer interaction workshop. The experiments involve supersonic flows in wind tunnels with a shock generator that directs an oblique shock wave toward the boundary layer along one of the walls of the wind tunnel. The Wind-US calculations utilized structured grid computations performed in Reynolds-averaged Navier-Stokes mode. Four turbulence models were investigated: the Spalart-Allmaras one-equation model, the Menter Baseline and Shear Stress Transport k-omega two-equation models, and an explicit algebraic stress k-omega formulation. Effects of grid resolution and upwinding scheme were also considered. The results from the CFD calculations are compared to particle image velocimetry (PIV) data from the experiments. As expected, turbulence model effects dominated the accuracy of the solutions with upwinding scheme selection indicating minimal effects.

  6. Aerosol-Radiation-Cloud Interactions in the South-East Atlantic: Future Suborbital Activities to Address Knowledge Gaps in Satellite and Model Assessments

    Science.gov (United States)

    Redemann, Jens; Wood, R.; Zuidema, P.; Haywood, J.; Piketh, S.; Formenti, P.; L'Ecuyer, T.; Kacenelenbogen, M.; Segal-Rosenheimer, M.; Shinozuka, Y.; hide

    2016-01-01

    Southern Africa produces almost a third of the Earth's biomass burning (BB) aerosol particles. Particles lofted into the mid-troposphere are transported westward over the South-East (SE) Atlantic, home to one of the three permanent subtropical stratocumulus (Sc) cloud decks in the world. The SE Atlantic stratocumulus deck interacts with the dense layers of BB aerosols that initially overlay the cloud deck, but later subside and may mix into the clouds. These interactions include adjustments to aerosol-induced solar heating and microphysical effects, and their global representation in climate models remains one of the largest uncertainties in estimates of future climate. Hence, new observations over the SE Atlantic have significant implications for global climate change scenarios. Our understanding of aerosol-cloud interactions in the SE Atlantic is hindered both by the lack of knowledge on aerosol and cloud properties, as well as the lack of knowledge about detailed physical processes involved. Most notably, we are missing knowledge on the absorptive and cloud nucleating properties of aerosols, including their vertical distribution relative to clouds, on the locations and degree of aerosol mixing into clouds, on the processes that govern cloud property adjustments, and on the importance of aerosol effects on clouds relative to co-varying synoptic scale meteorology. We discuss the current knowledge of aerosol and cloud property distributions based on satellite observations and sparse suborbital sampling. Recent efforts to make full use of A-Train aerosol sensor synergies will be highlighted. We describe planned field campaigns in the region to address the existing knowledge gaps. Specifically, we describe the scientific objectives and implementation of the five synergistic, international research activities aimed at providing some of the key aerosol and cloud properties and a process-level understanding of aerosol-cloud interactions over the SE Atlantic: NASA

  7. The Far Infrared Spectroscopic Explorer (FIRSPEX): probing the lifecycle of the ISM in the universe

    Science.gov (United States)

    Rigopoulou, D.; Caldwell, M.; Ellison, B.; Pearson, C.; Caux, E.; Cooray, A.; Gallego, J. D.; Gerin, M.; Goicoechea, J. R.; Goldsmith, P.; Kramer, C.; Lis, D. C.; Molinari, S.; Ossenkopf-Okada, V.; Savini, G.; Tan, B. K.; Tielens, X.; Viti, S.; Wiedner, M.; Yassin, G.

    2016-07-01

    The Far Infrared Spectroscopic Explorer (FIRSPEX) is a novel European-led astronomy mission concept developed to enable large area ultra high spectroscopic resolution surveys in the THz regime. FIRSPEX opens up a relatively unexplored spectral and spatial parameter space that will produce an enormously significant scientific legacy by focusing on the properties of the multi-phase ISM, the assembly of molecular clouds in our Galaxy and the onset of star formation; topics which are fundamental to our understanding of galaxy evolution. The mission uses a heterodyne instrument and a ~1.2 m primary antenna to scan large areas of the sky in a number of discreet spectroscopic channels from L2. The FIRSPEX bands centered at [CI] 809 GHz, [NII]1460 GHz, [CII]1900 GHz and [OI]4700 GHz have been carefully selected to target key atomic and ionic fine structure transitions difficult or impossible to access from the ground but fundamental to the study of the multi-phase ISM in the Universe. The need for state-of-the-art sensitivity dictates the use of superconducting mixers configured either as tunnel junctions or hot electron bolometers. This technology requires cooling to low temperatures, approaching 4K, in order to operate. The receivers will operate in double sideband configuration providing a total of 7 pixels on the sky. FIRSPEX will operate from L2 in both survey and pointed mode enabling velocity resolved spectroscopy of large areas of sky as well as targeted observations.

  8. An energy balance model exploration of the impacts of interactions between surface albedo, water vapour and clouds on polar amplification

    Science.gov (United States)

    Sodergren, Helena; McDonald, Adrian; Bodeker, Greg

    2017-04-01

    The interactions between surface albedo, water vapour and clouds, and how these interactions change with carbon dioxide (CO2) concentrations in the atmosphere, are examined with a newly developed energy balance model. A particular focus is the non-linear interactions of these climate system attributes on polar amplification. Polar amplification is defined here as the ratio of the annual rate of surface warming over the polar regions (latitudes poleward of 60o) to the surface warming over equatorial regions (latitudes equatorward of 30o), and is termed the polar amplification factor. Changes in surface albedo plays a major role in polar amplification as might be expected, due to its amplifying effects of CO2 -induced warming of the polar regions, and relatively small warming effects in the equatorial regions. When considered in isolation from the other climate system components, i.e. when water vapour and cloud cover are prescribed, changes in surface albedo result in a polar amplification factor of 4.83 for a doubling of CO2, compared to 5.54 for the full feedback simulation, i.e. the simulation where all three components are allowed to simultaneously change with temperature. In our simple model framework, changes in surface albedo are responsible for 43% of the polar warming from the full feedback run, and 49% of the equatorial warming. The polar amplification for the simulation with isolated climate feedback from cloud cover variations is smaller than the simulation with isolated surface albedo feedback, mainly due to a weaker warming in the polar regions. The polar amplification factor for the isolated cloud cover feedback simulation is 3.73, contributing 30% of the warming in the polar regions to the full feedback simulation and 45% in the equatorial regions. The amplifying effect from changing surface albedo on polar warming and polar amplification is enhanced when surface albedo interacts with cloud cover or water vapour. The polar amplification factor is

  9. Multiagent/Multiobjective Interaction Game System for Service Provisioning in Vehicular Cloud

    National Research Council Canada - National Science Library

    Aloqaily, Moayad; Kantarci, Burak; Mouftah, Hussein T

    2016-01-01

    The increasing number of applications based on the Internet of Things, as well as advances in wireless communication, information and communication technology, and mobile cloud computing, has allowed...

  10. Importance of Raman Lidar Aerosol Extinction Measurements for Aerosol-Cloud Interaction Studies

    Directory of Open Access Journals (Sweden)

    Han Zaw

    2016-01-01

    Full Text Available Using a UV Raman Lidar for aerosol extinction, and combining Microwave Radiometer derived Liquid Water Path (LWP with Multifilter Rotating Shadowband Radiometer derived Cloud Optical depth, to get cloud effective radius (Reff, we observe under certain specialized conditions, clear signatures of the Twomey Aerosol Indirect effect on cloud droplet properties which are consistent with the theoretical bounds. We also show that the measurement is very sensitive to how far the aerosol layer is from the cloud base and demonstrate that surface PM25 is far less useful. Measurements from both the DOE ARM site and new results at CCNY are presented.

  11. Analysis of Dynamic Interactions between Different Drivetrain Components with a Detailed Wind Turbine Model

    Science.gov (United States)

    Bartschat, A.; Morisse, M.; Mertens, A.; Wenske, J.

    2016-09-01

    The presented work describes a detailed analysis of the dynamic interactions among mechanical and electrical drivetrain components of a modern wind turbine under the influence of parameter variations, different control mechanisms and transient excitations. For this study, a detailed model of a 2MW wind turbine with a gearbox, a permanent magnet synchronous generator and a full power converter has been developed which considers all relevant characteristics of the mechanical and electrical subsystems. This model includes an accurate representation of the aerodynamics and the mechanical properties of the rotor and the complete mechanical drivetrain. Furthermore, a detailed electrical modelling of the generator, the full scale power converter with discrete switching devices, its filters, the transformer and the grid as well as the control structure is considered. The analysis shows that, considering control measures based on active torsional damping, interactions between mechanical and electrical subsystems can significantly affect the loads and thus the individual lifetime of the components.

  12. Descriptor Data Bank (DDB): A Cloud Platform for Multiperspective Modeling of Protein-Ligand Interactions.

    Science.gov (United States)

    Ashtawy, Hossam M; Mahapatra, Nihar R

    2018-01-22

    Protein-ligand (PL) interactions play a key role in many life processes such as molecular recognition, molecular binding, signal transmission, and cell metabolism. Examples of interaction forces include hydrogen bonding, hydrophobic effects, steric clashes, electrostatic contacts, and van der Waals attractions. Currently, a large number of hypotheses and perspectives to model these interaction forces are scattered throughout the literature and largely forgotten. Instead, had they been assembled and utilized collectively, they would have substantially improved the accuracy of predicting binding affinity of protein-ligand complexes. In this work, we present Descriptor Data Bank (DDB), a data-driven platform on the cloud for facilitating multiperspective modeling of PL interactions. DDB is an open-access hub for depositing, hosting, executing, and sharing descriptor extraction tools and data for a large number of interaction modeling hypotheses. The platform also implements a machine-learning (ML) toolbox for automatic descriptor filtering and analysis and scoring function (SF) fitting and prediction. The descriptor filtering module is used to filter out irrelevant and/or noisy descriptors and to produce a compact subset from all available features. We seed DDB with 16 diverse descriptor extraction tools developed in-house and collected from the literature. The tools altogether generate over 2700 descriptors that characterize (i) proteins, (ii) ligands, and (iii) protein-ligand complexes. The in-house descriptors we extract are protein-specific which are based on pairwise primary and tertiary alignment of protein structures followed by clustering and trilateration. We built and used DDB's ML library to fit SFs to the in-house descriptors and those collected from the literature. We then evaluated them on several data sets that were constructed to reflect real-world drug screening scenarios. We found that multiperspective SFs that were constructed using a large number

  13. Kelvin-Helmholtz instability at the magnetopause and the solar wind - magnetosphere interaction

    Energy Technology Data Exchange (ETDEWEB)

    Ziemkiewicz-Dabrowska, J. (Polska Akademia Nauk, Warsaw. Centrum Astronomiczne)

    1980-01-01

    Some basic properties of the instability caused by inhomogeneous mass flow are reviewed, and papers dealing with various aspects of this phenomenon are discussed. The Kelvin-Helmholtz instability is discussed on the basis of magnetohydrodynamics and CGL equations, and the effects of the finite Larmor radius of ions are taken into account. The results related to the problem of the magnetopause stability are listed and the possibility of viscous interaction at the solar wind-magnetosphere boundary is discussed.

  14. Modelling the solar wind interaction with Mercury by a quasi-neutral hybrid model

    Directory of Open Access Journals (Sweden)

    E. Kallio

    2003-11-01

    Full Text Available Quasi-neutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physics research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as the effects associated with the ions’ finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasi-neutral hybrid models have been used to study the solar wind interaction with the non-magnetised Solar System bodies of Mars, Venus, Titan and comets. Localized, two-dimensional hybrid model runs have also been made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasi-neutral hybrid model. In this paper we present a new quasi-neutral hybrid model developed to study various processes associated with the Mercury-solar wind interaction. Emphasis is placed on addressing advantages and disadvantages of the approach to study different plasma physical processes near the planet. The basic assumptions of the approach and the algorithms used in the new model are thoroughly presented. Finally, some of the first three-dimensional hybrid model runs made for Mercury are presented. The resulting macroscopic plasma parameters and the morphology of the magnetic field demonstrate the applicability of the new approach to study the Mercury-solar wind interaction globally. In addition, the real advantage of the kinetic hybrid model approach is to study the property of individual ions, and the study clearly demonstrates the large potential of the approach to address these more detailed issues by a quasi-neutral hybrid model in the future.Key words. Magnetospheric physics (planetary magnetospheres; solar wind-magnetosphere interactions – Space plasma

  15. Foil clouds measurements of the winter wind field and their analysis over northern Norway in the height of 75 to 100 km. Durchfuehrung und Analyse von Folienwolkenmessungen des Windfeldes im Winter ueber Nordnorwegen in 75 bis 100 km Hoehe

    Energy Technology Data Exchange (ETDEWEB)

    Bacher, A.

    1991-04-01

    Slowly descending foil chaff clouds tracked by radar after deployment from meteorological rockets were employed in the study of small scale dynamics of the upper mesosphere at Andenes, 69{sup 0} N, 16{sup 0} E, Norway, as part of the DYANA atmospheric science campaign January to March 1990. Vertical profiles of the horizontal wind are deduced from data obtained in 22 experiments, plus a number of independent measurements, after analyzing possible systematic experimental errors/resolution limits (cloud extent, low fall speed). Profiles of vertical wind velocity are given, too, but systematic errors often dominante. Wind variation with height is seen to be mostly dominated by internal gravity waves; often few wavelengths seem prominent in the instantaneous vertical wave structure. Induced windshear is examined in connection with static stability, leading to vertical profiles of the Richardson number. The new set of data reduction software developped, e.g. special fitting Splines, allows quick, standardized and accurate wind determination. (orig.).

  16. TWO REGIMES OF INTERACTION OF A HOT JUPITER’S ESCAPING ATMOSPHERE WITH THE STELLAR WIND AND GENERATION OF ENERGIZED ATOMIC HYDROGEN CORONA

    Energy Technology Data Exchange (ETDEWEB)

    Shaikhislamov, I. F.; Prokopov, P. A.; Berezutsky, A. G.; Zakharov, Yu. P.; Posukh, V. G. [Institute of Laser Physics SB RAS, Novosibirsk (Russian Federation); Khodachenko, M. L.; Lammer, H.; Kislyakova, K. G.; Fossati, L. [Space Research Institute, Austrian Acad. Sci., Graz (Austria); Johnstone, C. P., E-mail: maxim.khodachenko@oeaw.ac.at [Department of Astrophysics, University of Vienna, Vienna (Austria)

    2016-12-01

    The interaction of escaping the upper atmosphere of a hydrogen-rich non-magnetized analog of HD 209458b with a stellar wind (SW) of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic (HD) model. A realistic Sun-like spectrum of X-ray and ultraviolet radiation, which ionizes and heats the planetary atmosphere, together with hydrogen photochemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric HD outflow. Two different regimes of the planetary and SW interaction have been modeled. These are: (1) the “ captured by the star ” regime, when the tidal force and pressure gradient drive the planetary material beyond the Roche lobe toward the star, and (2) the “ blown by the wind ” regime, when sufficiently strong SW confines the escaping planetary atmosphere and channels it into the tail. The model simulates in detail the HD interaction between the planetary atoms, protons and the SW, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud, either as a paraboloid shell between the ionopause and bowshock (for the “ blown by the wind ” regime), or a turbulent layer at the contact boundary between the planetary stream and SW (for the “ captured by the star ” regime) are of importance for the interpretation of Ly α absorption features in exoplanetary transit spectra and characterization of the plasma environments.

  17. Experimental Simulation of Solar Wind Interactions with Magnetic Dipole Fields above Insulating Surfaces

    Science.gov (United States)

    Munsat, Tobin; Deca, Jan; Han, Jia; Horanyi, Mihaly; Wang, Xu; Werner, Greg; Yeo, Li Hsia; Fuentes, Dominic

    2017-10-01

    Magnetic anomalies on the surfaces of airless bodies such as the Moon interact with the solar wind, resulting in both magnetic and electrostatic deflection of the charged particles and thus localized surface charging. This interaction is studied in the Colorado Solar Wind Experiment with large-cross-section ( 300 cm2) high-energy flowing plasmas (100-800 eV beam ions) that are incident upon a magnetic dipole embedded under various insulating surfaces. Measured 2D plasma potential profiles indicate that in the dipole lobe regions, the surfaces are charged to high positive potentials due to the collection of unmagnetized ions, while the electrons are magnetically shielded. At low ion beam energies, the surface potential follows the beam energy in eV. However, at high energies, the surface potentials in the electron-shielded regions are significantly lower than the beam energies. A series of studies indicate that secondary electrons are likely to play a dominant role in determining the surface potential. Early results will also be presented from a second experiment, in which a strong permanent magnet with large dipole moment (0.55 T, 275 A*m2) is inserted into the flowing plasma beam to replicate aspects of the solar wind interaction with the earth's magnetic field. This work is supported by the NASA SSERVI program.

  18. European regulations of the radio spectrum, ISM use and safety.

    Science.gov (United States)

    Van Loock, W

    2001-01-01

    In Europe, many standards dealing with equipment electromagnetic compatibility (EMC) are threatening the ISM use of the radio spectrum. The basis and the shortcomings of the standards are discussed and compared with the actual electromagnetic environment. The standards for equipment are too strict involving higher investment costs. High frequency and microwave power applications are therefore likely to slow down. Guidelines and standards for protection of human exposure to electromagnetic fields (EMF) are too conservative and have no reference to ISM applications. Only a leakage standard for the domestic microwave oven and similar equipment exist. Some recommendations are presented for improvement.

  19. Evaluating the impact of ERP systems on SC performance with ISM

    Directory of Open Access Journals (Sweden)

    Cristina López Vargas

    2017-06-01

    Full Text Available Most companies nowadays have already implemented on-premise or cloud -based ERP systems into their IT infraestrutures. These packages allow firms to integrate, standardize and execute the whole business processes in real time, improving their productivity and operational efficiency. Previous studies highlight their beneficial effects go beyond the single firm. Indeed, ERP system can assist supply‐chain partners to work in close coordination. In order to reach a better understanding in this matter, the present study aims to develop a comprehensive framework. This will represent the benefits derived from ERP adoption in Supply Chain performance. In doing so, we applied an interpretive structural modelling (ISM. Finally, we provide a case study that explores the viability of this framework.

  20. Silicon Photonics Cloud (SiCloud)

    DEFF Research Database (Denmark)

    DeVore, P. T. S.; Jiang, Y.; Lynch, M.

    2015-01-01

    Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.......Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths....

  1. The CloudBoard Research Platform: an interactive whiteboard for corporate users

    Science.gov (United States)

    Barrus, John; Schwartz, Edward L.

    2013-03-01

    Over one million interactive whiteboards (IWBs) are sold annually worldwide, predominantly for classroom use with few sales for corporate use. Unmet needs for IWB corporate use were investigated and the CloudBoard Research Platform (CBRP) was developed to investigate and test technology for meeting these needs. The CBRP supports audio conferencing with shared remote drawing activity, casual capture of whiteboard activity for long-term storage and retrieval, use of standard formats such as PDF for easy import of documents via the web and email and easy export of documents. Company RFID badges and key fobs provide secure access to documents at the board and automatic logout occurs after a period of inactivity. Users manage their documents with a web browser. Analytics and remote device management is provided for administrators. The IWB hardware consists of off-the-shelf components (a Hitachi UST Projector, SMART Technologies, Inc. IWB hardware, Mac Mini, Polycom speakerphone, etc.) and a custom occupancy sensor. The three back-end servers provide the web interface, document storage, stroke and audio streaming. Ease of use, security, and robustness sufficient for internal adoption was achieved. Five of the 10 boards installed at various Ricoh sites have been in daily or weekly use for the past year and total system downtime was less than an hour in 2012. Since CBRP was installed, 65 registered users, 9 of whom use the system regularly, have created over 2600 documents.

  2. Aerosol-radiation-cloud interactions in the South-East Atlantic: first results from the ORACLES-2016 deployment and plans for future activities

    Science.gov (United States)

    Redemann, J.; Wood, R.; Zuidema, P.; Haywood, J. M.; Piketh, S.; Formenti, P.; Abel, S.

    2016-12-01

    Southern Africa produces almost a third of the Earth's biomass burning (BB) aerosol particles. Particles lofted into the mid-troposphere are transported westward over the South-East (SE) Atlantic, home to one of the three permanent subtropical stratocumulus (Sc) cloud decks in the world. The SE Atlantic stratocumulus deck interacts with the dense layers of BB aerosols that initially overlay the cloud deck, but later subside and may mix into the clouds. These interactions include adjustments to aerosol-induced solar heating and microphysical effects, and their global representation in climate models remains one of the largest uncertainties in estimates of future climate. Hence, new observations over the SE Atlantic have significant implications for regional and global climate change predictions. Our understanding of aerosol-cloud interactions in the SE Atlantic is severely limited. Most notably, we are missing knowledge on the absorptive and cloud nucleating properties of aerosols, including their vertical distribution relative to clouds, on the locations and degree of aerosol mixing into clouds, on the processes that govern cloud property adjustments, and on the importance of aerosol effects on clouds relative to co-varying synoptic scale meteorology. We describe first results from various synergistic, international research activities aimed at studying aerosol-cloud interactions in the region: NASA's airborne ORACLES (ObseRvations of Aerosols Above Clouds and Their IntEractionS) deployment in August/September of 2016, the DoE's LASIC (Layered Atlantic Smoke Interactions with Clouds) deployment of the ARM Mobile Facility to Ascension Island (June 2016 - October 2017), the ground-based components of CNRS' AEROCLO-sA (Aerosols Clouds and Fog over the west coast of southern Africa), and ongoing regional-scale integrative, process-oriented science efforts as part of SEALS-sA (Sea Earth Atmosphere Linkages Study in southern Africa). We expect to describe experimental

  3. Cirrus cloud-temperature interactions in the tropical tropopause layer: a case study

    Directory of Open Access Journals (Sweden)

    J. R. Taylor

    2011-10-01

    Full Text Available Thin cirrus clouds in the Tropical Tropopause Layer (TTL have important ramifications for radiative transfer, stratospheric humidity, and vertical transport. A horizontally extensive and vertically thin cirrus cloud in the TTL was detected by the Cloud Aerosol LIDAR and Infrared Pathfinder Satellite Observations (CALIPSO on 27–29 January 2009 in the Tropical Eastern Pacific region, distant from any regions of deep convection. These observations indicate that the cloud is close to 3000 km in length along the CALIPSO orbit track. Measurements over this three day period indicate that the cloud event extended over a region from approximately 15° S to 10° N and 90° W to 150° W and may be one of the most extensive cirrus events ever observed. Coincident temperature observations from the Constellation of Observing Satellites for Meteorology, Ionosphere, and Climate (COSMIC suggest that the cloud formed in-situ as a result of a cold anomaly arising from a midlatitude intrusion. The event appears to last for up to 2 days and the temperature observations do not show any indication of the expected infrared heating. It is hypothesized that the cloud could be maintained by either nucleation of numerous small ice crystals that don't sediment or by multiple localized ice nucleation events driven by temperature variability at scales smaller than the overall cloud field, producing small ice-crystal sizes which have sufficiently long residence times (≈53 h to maintain the cloud. It is possible that the residence times are augmented by vertical motion which could also act to offset the expected infrared heating. Further observations of similar events will be required in order to conclusively explain this curious cloud.

  4. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.

    Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  5. Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet Flows with Shock Interactions

    Science.gov (United States)

    Cliff, Susan E.; Denison, Marie; Moini-Yekta, Shayan; Morr, Donald E.; Durston, Donald A.

    2016-01-01

    NASA and the U.S. aerospace industry are performing studies of supersonic aircraft concepts with low sonic boom pressure signatures. The computational analyses of modern aircraft designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty remains in the aft signatures due to boundary layer and nozzle exhaust jet effects. Wind tunnel testing without inlet and nozzle exhaust jet effects at lower Reynolds numbers than in-flight make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel is planned for February 2016 to address the nozzle jet effects on sonic boom. The experiment will provide pressure signatures of test articles that replicate waveforms from aircraft wings, tails, and aft fuselage (deck) components after passing through cold nozzle jet plumes. The data will provide a variety of nozzle plume and shock interactions for comparison with computational results. A large number of high-fidelity numerical simulations of a variety of shock generators were evaluated to define a reduced collection of suitable test models. The computational results of the candidate wind tunnel test models as they evolved are summarized, and pre-test computations of the final designs are provided.

  6. Meltwater produced by wind-albedo interaction stored in an East Antarctic ice shelf

    Science.gov (United States)

    Lenaerts, J. T. M.; Lhermitte, S.; Drews, R.; Ligtenberg, S. R. M.; Berger, S.; Helm, V.; Smeets, C. J. P. P.; Broeke, M. R. Van Den; van de Berg, W. J.; van Meijgaard, E.; Eijkelboom, M.; Eisen, O.; Pattyn, F.

    2017-01-01

    Surface melt and subsequent firn air depletion can ultimately lead to disintegration of Antarctic ice shelves causing grounded glaciers to accelerate and sea level to rise. In the Antarctic Peninsula, foehn winds enhance melting near the grounding line, which in the recent past has led to the disintegration of the most northerly ice shelves. Here, we provide observational and model evidence that this process also occurs over an East Antarctic ice shelf, where meltwater-induced firn air depletion is found in the grounding zone. Unlike the Antarctic Peninsula, where foehn events originate from episodic interaction of the circumpolar westerlies with the topography, in coastal East Antarctica high temperatures are caused by persistent katabatic winds originating from the ice sheet’s interior. Katabatic winds warm and mix the air as it flows downward and cause widespread snow erosion, explaining >3 K higher near-surface temperatures in summer and surface melt doubling in the grounding zone compared with its surroundings. Additionally, these winds expose blue ice and firn with lower surface albedo, further enhancing melt. The in situ observation of supraglacial flow and englacial storage of meltwater suggests that ice-shelf grounding zones in East Antarctica, like their Antarctic Peninsula counterparts, are vulnerable to hydrofracturing.

  7. Standard metrics and methods for conducting Avian/wind energy interaction studies

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R.L. [California Energy Commission, Sacramento, CA (United States); Davis, H. [National Renewable Energy Lab., Golden, CO (United States); Kendall, W. [National Biological Service, Laurel, MD (United States)] [and others

    1997-12-31

    The awareness of the problem of avian fatalities at large scale wind energy developments first emerged in the late 1980`s at the Altamont Pass Wind Resource Area (WRA) in Central California. Observations of dead raptors at the Altamont Pass WRA triggered concern on the part of regulatory agencies, environmental/conservation groups, resource agencies, and wind and electric utility industries. This led the California Energy Commission staff, along with the planning departments of Alameda, Contra Costa, and Solano counties, to commission a study of bird mortality at the Altamont Pass WRA. In addition to the Altamont Pass WRA, other studies and observations have established that windplants kill birds. Depending upon the specific factors, this may or may not be a serious problem. The current level of scrutiny and caution exhibited during the permitting of a new windplant development in the United States results in costly delays and studies. This is occurring during a highly competitive period for electrical production companies in the USA. Clarification of the bird fatality issue is needed to bring it into perspective. This means standardizing metrics, defining terms, and recommending methods to be used in addressing or studying wind energy/bird interactions.

  8. Wind turbine generator interaction with diesel generators on an isolated power system

    Science.gov (United States)

    Scott, G. W.; Wilreker, V. F.; Shaltens, R. K.

    1983-01-01

    The results of a dynamic interaction investigation to characterize any disturbances caused by interfacing the Mod 0A wind turbine (150 kW configuration) with the Block Island utility diesel generator grid are reported. The tests were run when only two diesel generators were on line, and attention was given to power, frequency, and voltage time profiles. The interconnected system was examined in the start-up and synchronization phase, normal shutdown and cut-out of the wind turbine, during fixed pitch generation, and during variable pitch operation. Governors were installed on the diesel generators to accommodate the presence of wind-derived electricity. The blade pitch control was set to maintain power at 150 kW or below. Power and voltage transients were insignificant during start-up and shutdown, and frequency aberrations were within the range caused by load fluctuations. It is concluded that wind turbine generation can be successfully implemented by an isolated utility, even with a significant penetration to the total grid output.

  9. Dynamic analysis of a 5-MW tripod offshore wind turbine by considering fluid-structure interaction

    Science.gov (United States)

    Zhang, Li-wei; Li, Xin

    2017-10-01

    Fixed offshore wind turbines usually have large underwater supporting structures. The fluid influences the dynamic characteristics of the structure system. The dynamic model of a 5-MW tripod offshore wind turbine considering the pile-soil system and fluid structure interaction (FSI) is established, and the structural modes in air and in water are obtained by use of ANSYS. By comparing low-order natural frequencies and mode shapes, the influence of sea water on the free vibration characteristics of offshore wind turbine is analyzed. On basis of the above work, seismic responses under excitation by El-Centro waves are calculated by the time-history analysis method. The results reveal that the dynamic responses such as the lateral displacement of the foundation and the section bending moment of the tubular piles increase substantially under the influence of the added-mass and hydrodynamic pressure of sea water. The method and conclusions presented in this paper can provide a theoretical reference for structure design and analysis of offshore wind turbines fixed in deep seawater.

  10. An ISM approach for analyzing the factors in technology transfer

    Directory of Open Access Journals (Sweden)

    Mohammad Mahdavi Mazdeh

    2015-07-01

    Full Text Available Technology transfer, from research and technology organizations (RTOs toward local industries, is considered as one of important and significant strategies for countries' industrial development. In addition to recover the enormous costs of research and development for RTOs, successful technology transfer from RTOs toward local firms forms technological foundations and develops the ability to enhance the competitiveness of firms. Better understanding of factors influencing process of technology transfer helps RTOs and local firms prioritize and manage their resources in an effective and efficient way to maximize the success of technology transfer. This paper aims to identify important effective factors in technology transfer from Iranian RTOs and provides a comprehensive model, which indicate the interactions of these factors. In this regard, first, research background is reviewed and Cummings and Teng’s model (2003 [Cummings, J. L., & Teng, B.-S. (2003. Transferring R&D knowledge: The key factors affecting knowledge transfer success. Journal of Engineering and Technology Management, 20(1-2, 39-68.] was selected as the basic model in this study and it was modified through suggesting new factors identified from literature of inter-organizational knowledge and technology transfer and finally a Delphi method was applied for validation of modified model. Then, research conducted used Interpretive Structural Modeling (ISM to evaluate the relationship between the factors of final proposed model. Results indicate that there were twelve factors influencing on technology transfer process from Iranian RTOs to local firms and also the intensity of absorption capability in transferee could influence on the intensity of desorption capability in transferor.

  11. An optimal control framework for dynamic induction control of wind farms and their interaction with the atmospheric boundary layer

    Science.gov (United States)

    Munters, W.; Meyers, J.

    2017-03-01

    Complex turbine wake interactions play an important role in overall energy extraction in large wind farms. Current control strategies optimize individual turbine power, and lead to significant energy losses in wind farms compared with lone-standing wind turbines. In recent work, an optimal coordinated control framework was introduced (Goit & Meyers 2015 J. Fluid Mech. 768, 5-50 (doi:10.1017/jfm.2015.70)). Here, we further elaborate on this framework, quantify the influence of optimization parameters and introduce new simulation results for which gains in power production of up to 21% are observed. This article is part of the themed issue 'Wind energy in complex terrains'.

  12. The Distribution and Ages of Star Clusters in the Small Magellanic Cloud: Constraints on the Interaction History of the Magellanic Clouds

    Science.gov (United States)

    Bitsakis, Theodoros; González-Lópezlira, R. A.; Bonfini, P.; Bruzual, G.; Maravelias, G.; Zaritsky, D.; Charlot, S.; Ramírez-Siordia, V. H.

    2018-02-01

    We present a new study of the spatial distribution and ages of the star clusters in the Small Magellanic Cloud (SMC). To detect and estimate the ages of the star clusters we rely on the new fully automated method developed by Bitsakis et al. Our code detects 1319 star clusters in the central 18 deg2 of the SMC we surveyed (1108 of which have never been reported before). The age distribution of those clusters suggests enhanced cluster formation around 240 Myr ago. It also implies significant differences in the cluster distribution of the bar with respect to the rest of the galaxy, with the younger clusters being predominantly located in the bar. Having used the same setup, and data from the same surveys as for our previous study of the LMC, we are able to robustly compare the cluster properties between the two galaxies. Our results suggest that the bulk of the clusters in both galaxies were formed approximately 300 Myr ago, probably during a direct collision between the two galaxies. On the other hand, the locations of the young (≤50 Myr) clusters in both Magellanic Clouds, found where their bars join the H I arms, suggest that cluster formation in those regions is a result of internal dynamical processes. Finally, we discuss the potential causes of the apparent outside-in quenching of cluster formation that we observe in the SMC. Our findings are consistent with an evolutionary scheme where the interactions between the Magellanic Clouds constitute the major mechanism driving their overall evolution.

  13. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF PAPAGAYO, COSTA RICA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology datasets were created using an automated intelligent algorithm which...

  14. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF PAPAGAYO, COSTA RICA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology Gulf of Papagayo, Costa Rica dataset was created using an automated...

  15. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF PANAMA, PANAMA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology datasets were created using an automated intelligent algorithm which...

  16. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF TEHUANTEPEC, MEXICO V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology Gulf of Tehuantepec, Mexico dataset was created using an automated...

  17. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF TEHUANTEPEC, MEXICO V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology datasets were created using an automated intelligent algorithm which...

  18. The Interaction between Clouds and Radiation Processes according to the NASA GEWEX SRB Release 3.0 Dataset

    Science.gov (United States)

    Zhang, T.; Stackhouse, P. W.; Gupta, S. K.; Cox, S. J.; Mikovitz, J. C.

    2009-05-01

    The NASA Global Energy and Water-cycle Experiment (GEWEX) Surface Radiation Budget (SRB) project data Release 3.0 covers a continuous 24-year period from July 1983 to June 2007. In addition to shortwave/longwave downward/upward fluxes at the Earth's surface and the top of atmosphere (TOA), this satellite-based dataset also provides cloud fraction, cloud optical depth and aerosol optical depth. The satellite covers the entire globe every 3 hours, and the highest temporal resolution of the dataset is thus 3hours. Three-hourly-monthly, daily and monthly means are derived therefrom. The spatial resolution of the dataset is 1 degree by 1degree. The dataset has been extensively validated against the datasets of the Baseline Surface Radiation Network (BSRN), the World Radiation Data Centre (WRDC) as well as the Global Energy Balance Archive (GEBA). Fairly good agreement has been achieved. This dataset provides a wealth of opportunities to study how the clouds and radiation processes in the atmosphere interact with each other and with other factors on regional and global scales. Such studies may enable us to better understand the dynamics of the global climate system. In this study, we first present SRB-BSRN comparisons under various cloud conditions, including clear-sky and all-sky conditions, as a way to validate the GEWEX SRB dataset. We then present some climatological statistics of shortwave/longwave radiation fluxes at the Earth's surface and TOA, cloud fraction, and cloud optical depth. We will attempt to show how these variables affect each other dynamically according to the NASA GEWEX SRB Release 3.0 data.

  19. Squeezed between shells? The origin of the Lupus I molecular cloud. APEX/LABOCA, Herschel, and Planck observations

    Science.gov (United States)

    Gaczkowski, B.; Preibisch, T.; Stanke, T.; Krause, M. G. H.; Burkert, A.; Diehl, R.; Fierlinger, K.; Kroell, D.; Ngoumou, J.; Roccatagliata, V.

    2015-12-01

    Context. The Lupus I cloud is found between the Upper Scorpius (USco) and the Upper Centaurus-Lupus (UCL) subgroups of the Scorpius-Centaurus OB association, where the expanding USco H I shell appears to interact with a bubble currently driven by the winds of the remaining B-stars of UCL. Aims: We want to study how collisions of large-scale interstellar gas flows form and influence new dense clouds in the ISM. Methods: We performed LABOCA continuum sub-mm observations of Lupus I that provide for the first time a direct view of the densest, coldest cloud clumps and cores at high angular resolution. We complemented these data with Herschel and Planck data from which we constructed column density and temperature maps. From the Herschel and LABOCA column density maps we calculated probability density functions (PDFs) to characterize the density structure of the cloud. Results: The northern part of Lupus I is found to have, on average, lower densities, higher temperatures, and no active star formation. The center-south part harbors dozens of pre-stellar cores where density and temperature reach their maximum and minimum, respectively. Our analysis of the column density PDFs from the Herschel data show double-peak profiles for all parts of the cloud, which we attribute to an external compression. In those parts with active star formation, the PDF shows a power-law tail at high densities. The PDFs we calculated from our LABOCA data trace the denser parts of the cloud showing one peak and a power-law tail. With LABOCA we find 15 cores with masses between 0.07 and 1.71 M⊙ and a total mass of ≈8 M⊙. The total gas and dust mass of the cloud is ≈164 M⊙ and hence ~5% of the mass is in cores. From the Herschel and Planck data we find a total mass of ≈174 M⊙ and ≈171 M⊙, respectively. Conclusions: The position, orientation, and elongated shape of Lupus I, the double-peak PDFs and the population of pre-stellar and protostellar cores could be explained by the

  20. The global morphology of the solar wind interaction with comet Churyumov-Gerasimenko

    Energy Technology Data Exchange (ETDEWEB)

    Mendis, D. A. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92037-0407 (United States); Horányi, M. [Laboratory of Atmospheric and Space Physics and Department of Physics, University of Colorado, Boulder, CO 80309-0392 (United States)

    2014-10-10

    The forthcoming Rosetta-Philae mission to comet 67P/Churyumov-Gerasimenko provides a novel opportunity to observe the variable nature of the solar wind interaction with a comet over an extended range of heliocentric distance. We use a simple analytical one-dimensional MHD model to estimate the sizes of the two most prominent features in the global structure of the solar wind interaction with a comet. When the heliocentric distance of the comet reaches d ≤ 1.51 AU, we expect a sharp shock to be observed, whose size would increase monotonically as the comet approaches the Sun, reaching a value ≅ 15, 000 km at perihelion (d ≅ 1.29 AU). Upstream of the shock, we expect the velocity-space distribution of the picked up cometary ions to be essentially gyrotropic. A well-defined ionopause is predicted when d ≤1.61 AU, though its size is expected to be only ≅25 km at perihelion, and it is expected to be susceptible to the 'flute' instability due to its small size. Consequently, we expect the magnetic field to penetrate all the way to the surface of the nucleus. We conclude with a brief discussion of the response of the comet's plasma environment to fast temporal variations in the solar wind.

  1. Jet Interactions with Magnetized Clouds. Preliminary Results from PIC Code and Large-Scale Hydrodynamic Simulations for AGN Jets

    Science.gov (United States)

    2010-01-01

    accretion at the Schwarzschild radius is, therefore, L = η4.5x1020dm/dt in ergs s−1, where dm/dt is in gms s−1, or L = η3x1046dMo/dt in ergs s−1, where dM0/dt...vb is the beam ve- locity, and r2b is the beam radius . If the beam is significantly heated by the jet-cloud interaction, the beam will expand

  2. EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS

    Science.gov (United States)

    Falkovich, Gregory; Malinowski, Szymon P.

    2008-07-01

    elements of the puzzle, and those which combine them. Scales, assumptions and the conditions used in order to describe a particular single process of interest must be consistent with the conditions in clouds. The papers in this focus issue of New Journal of Physics collectively demonstrate (i) the variation in scientific approaches towards investigating cloud processes, (ii) the various stages of shaping elements of the puzzle, and (iii) some attempts to put the pieces together. These papers present just a small subset of loosely arranged elements in an initial stage of puzzle creation. Addressed by this issue is one of the important problems in our understanding of cloud processes—the interaction between cloud particles and turbulence. There is currently a gap between the cloud physics community and scientists working in wind tunnels, on turbulence theory and particle interactions. This collection is intended to narrow this gap by bringing together work by theoreticians, modelers, laboratory experimentalists and those who measure and observe actual processes in clouds. It forms a collage of contributions showing various approaches to cloud processes including: • theoretical works with possible applications to clouds (Bistagnino and Boffetta, Gustavsson et al), • an attempt to construct a phenomenological description of clouds and rain (Lovejoy and Schertzer), • simplified models designed to parameterize turbulence micro- and macro-effects (Celani et al, Derevyanko et al), • focused theoretical research aimed at particular cloud processes (Ayala et al, parts I and II, Wang et al), • laboratory and modeling studies of complex cloud processes (Malinowski et al). This collage is far from being complete but, hopefully, should give the reader a representative impression of the current state of knowledge in the field. We hope it will be useful to all scientists whose work is inspired by cloud processes. Focus on Cloud Physics Contents The equivalent size of cloud

  3. A unified model for age-velocity dispersion relations in Local Group galaxies: disentangling ISM turbulence and latent dynamical heating

    Science.gov (United States)

    Leaman, Ryan; Mendel, J. Trevor; Wisnioski, Emily; Brooks, Alyson M.; Beasley, Michael A.; Starkenburg, Else; Martig, Marie; Battaglia, Giuseppina; Christensen, Charlotte; Cole, Andrew A.; de Boer, T. J. L.; Wills, Drew

    2017-12-01

    We analyse age-velocity dispersion relations (AVRs) from kinematics of individual stars in eight Local Group galaxies ranging in mass from Carina (M* ∼ 106 M⊙) to M31 (M* ∼ 1011 M⊙). Observationally the σ versus stellar age trends can be interpreted as dynamical heating of the stars by giant molecular clouds, bars/spiral arms or merging subhaloes; alternatively the stars could have simply been born out of a more turbulent interstellar medium (ISM) at high redshift and retain that larger velocity dispersion till present day - consistent with recent integral field unit kinematic studies. To ascertain the dominant mechanism and better understand the impact of instabilities and feedback, we develop models based on observed star formation histories (SFHs) of these Local Group galaxies in order to create an evolutionary formalism that describes the ISM velocity dispersion due to a galaxy's evolving gas fraction. These empirical models relax the common assumption that the stars are born from gas that has constant velocity dispersion at all redshifts. Using only the observed SFHs as input, the ISM velocity dispersion and a mid-plane scattering model fits the observed AVRs of low-mass galaxies without fine tuning. Higher mass galaxies above Mvir ≳ 1011 M⊙ need a larger contribution from latent dynamical heating processes (for example minor mergers), in excess of the ISM model. Using the SFHs, we also find that supernovae feedback does not appear to be a dominant driver of the gas velocity dispersion compared to gravitational instabilities - at least for dispersions σ ≳ 25 km s-1. Together our results point to stars being born with a velocity dispersion close to that of the gas at the time of their formation, with latent dynamical heating operating with a galaxy mass-dependent efficiency. These semi-empirical relations may help constrain the efficiency of feedback and its impact on the physics of disc settling in galaxy formation simulations.

  4. Simulations of cloud-radiation interaction with imposed largescale dynamics from the DYNAMO northern sounding array

    Science.gov (United States)

    Wang, S.; Sobel, A. H.; Fridlind, A. M.

    2014-12-01

    The recently accomplished CINDY/DYNAMO project observed three MJO events in the equatorial Indian Ocean from October to December 2011. Analysis of the moist static energy budget by Sobel et al. (2014) indicates that the moist static energy anomalies in these events grew and were sustained to a significant extent by radiative feedbacks. We present here a study of radiative fluxes and clouds in a set of cloud-resolving simulations of the same DYNAMO MJO events. The simulations are driven by the large scale forcing dataset from the DYNAMO northern sounding array, and carried out in doubly-periodic domains using the WRF model. Simulated cloud properties and radiative fluxes are compared to the observed reflectivity from the SPolka radar and observed radiative fluxes from the CERES and VISST datasets. To accommodate the uncertainty in cloud microphysics, we have tested a number of single-moment (SM) and double-moment (DM) microphysical schemes in the WRF model. We find that in general the SM schemes tend to underestimate radiative flux anomalies in the active phase of the MJOs, while the DM schemes perform better but can instead overestimate radiative fluxes. All the microphysics schemes tested exhibit bias in the shape of the histograms of radiative fluxes and radar reflectivity. Analysis of CRM-simulated radar reflectivity indicates that this microphysics-related radiative flux uncertainty is closely related to how much stratiform clouds the CRM can simulate. SM schemes underestimate stratiform clouds by a factor of 2, while DM schemes simulate much more stratiform cloud, closer to observation, but shows a peak in the histogram at 15-20 dBz that is absent in observations. The double-moment Morrison scheme appears to give the best results in TOA fluxes associated with the MJO convective anomalies despite biases in the histograms of cloud and radiative fluxes.

  5. Effects of Vertical Wind Shear, Radiation, and Ice Clouds on Precipitation Distributions During a Landfall of Severe Tropical Storm, Bilis (2006

    Directory of Open Access Journals (Sweden)

    Donghai Wang

    2013-01-01

    Full Text Available Torrential rainfall responses to vertical wind shear, radiation, and ice clouds during the landfall of severe Tropical Storm, Bilis (2006 are investigated via a rainfall partitioning analysis of grid-scale sensitivity experiment data. The rainfall data are partitioned into eight types based on surface rainfall budget. The largest contributions to total rainfall come from local atmospheric moistening, water vapor convergence, and hydrometeor loss/convergence (Type 3; 29% when the large-scale upward motions occurred only in the upper troposphere on 15 July 2006. When the large-scale upward motion center moved to the mid troposphere on 16 July, Type 3 hydrometeor loss/convergence (26% plus local atmospheric drying, water vapor divergence, and hydrometeor loss/convergence (Type 5; 25% show equally important contributions to total rainfall.

  6. Observations of the Interaction and/or Transport of Aerosols with Cloud or Fog during DRAGON Campaigns from AERONET Ground-Based Remote Sensing

    Science.gov (United States)

    Eck, Thomas; Holben, Brent; Schafer, Joel; Giles, David; Kim, Jhoon; Kim, Young; Sano, Itaru; Reid, Jeffrey; Pickering, Kenneth; Crawford, James; Sinyuk, Alexander; Trevino, Nathan

    2014-05-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Recent major DRAGON field campaigns in Japan and South Korea (Spring 2012) and California (Winter 2013) have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth signal for these cases of persistent and extensive cloud cover. Additionally, extensive fog that was coincident with aerosol layer height on some days in both Korea and California resulted in large increases in fine mode aerosol radius, with a mode of cloud-processed or residual aerosol of radius ~0.4-0.5 micron sometimes observed. Cloud processed aerosol may occur much more frequently than AERONET data suggest due to inherent difficulty in observing aerosol properties near clouds from remote sensing observations. These biases of aerosols associated with clouds would likely be even greater for satellite remote sensing retrievals of aerosol properties near clouds due to 3-D effects and sub-pixel cloud contamination issues.

  7. Analysis of the Interaction and Transport of Aerosols with Cloud or Fog in East Asia from AERONET and Satellite Remote Sensing: 2012 DRAGON Campaigns and Climatological Data

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Lynch, P.; Schafer, J.; Giles, D. M.; Kim, J.; Kim, Y. J.; Sano, I.; Arola, A. T.; Munchak, L. A.; O'Neill, N. T.; Lyapustin, A.; Sayer, A. M.; Hsu, N. Y. C.; Randles, C. A.; da Silva, A. M., Jr.; Govindaraju, R.; Hyer, E. J.; Pickering, K. E.; Crawford, J. H.; Sinyuk, A.; Smirnov, A.

    2015-12-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. Major Distributed Regional Aerosol Gridded Observation Networks (DRAGON) field campaigns involving multiple AERONET sites in Japan and South Korea during Spring of 2012 have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth (AODf) signal from AERONET data for these cases of persistent and extensive cloud cover. Satellite retrievals of AOD from MODIS sensors (from Dark Target, Deep Blue and MAIAC algorithms) were also investigated to assess the issue of detectability of high AOD events associated with high cloud fraction. Underestimation of fine mode AOD by the Navy Aerosol Analysis and Prediction System (NAAPS) and by the NASA Modern-Era Retrospective Analysis For Research And Applications Aerosol Re-analysis (MERRAaero) models at very high AOD at sites in China and Korea was observed, especially for observations that are cloud screened by AERONET (Level 2 data). Additionally, multi-year monitoring at several AERONET sites are examined for climatological statistics of cloud screening of fine mode aerosol events. Aerosol that has been affected by clouds or the near-cloud environment may be more prevalent than AERONET data suggest due to inherent difficulty in

  8. An Assessment of Uncertainties in the NASA GISS ModelE GCM due to Variations in the Representation of Aerosol/Cloud Interactions

    Science.gov (United States)

    Persad, G. G.; Menon, S.; Sednev, I.

    2008-12-01

    Aerosol indirect effects are known to have a significant impact on the evolution of the climate system. However, their representation via cloud/aerosol microphysics remains a major source of uncertainty in climate models. This study assesses uncertainties in the NASA Goddard Institute for Space Studies (GISS) ModelE global climate model produced by different representations of the cloud/aerosol interaction scheme. By varying the complexity of the cloud microphysics scheme included in the model and analyzing the range of results against cloud properties obtained from satellite retrievals, we evaluate the effect of the different schemes on climate. We examine four sets of simulations with the GISS ModelE: (1) using a new aerosol/cloud microphysics package implemented in ModelE (based on the two-moment cloud microphysics scheme recently implemented in CCSM), (2) using a version of the microphysics scheme previously included in ModelE, (3) using prescribed aerosol concentrations and fixed cloud droplet number (the main link between aerosols and the cloud microphysics scheme), and (4) varying the environment conditions with which the new aerosol/cloud microphysics package is run. The global mean cloud properties are analyzed and compared to global mean ranges as obtained from satellite retrievals. Results show that important climate parameters, such as total cloud cover, can be underestimated by 8-15% using the new aerosol/cloud microphysics scheme. Liquid water path (LWP) is particularly affected by variations to the aerosol/cloud microphysics representation, exhibiting both global mean variations of ~20% and strong regional differences. Significant variability in LWP between the various simulations may be attributed to differences in the autoconversion scheme used in the differing representations of aerosol/cloud interactions. These LWP differences significantly affect radiative parameters, such as cloud optical depth and net cloud forcing (used to evaluate the

  9. MAVEN observations of the Mars upper atmosphere, ionosphere, and solar wind interactions

    Science.gov (United States)

    Jakosky, Bruce M.

    2017-09-01

    The Mars Atmosphere and Volatile Evolution (MAVEN) mission to Mars has been operating in orbit for more than a full Martian year. Observations are dramatically changing our view of the Mars upper atmosphere system, which includes the upper atmosphere, ionosphere, coupling to the lower atmosphere, magnetosphere, and interactions with the Sun and the solar wind. The data are allowing us to understand the processes controlling the present-day structure of the upper atmosphere and the rates of escape of gas to space. These will tell us the role that escape to space has played in the evolution of the Mars atmosphere and climate.

  10. MHD Model Results of Solar Wind Plasma Interaction with Mars and Comparison with MAVEN Observations

    Science.gov (United States)

    Ma, Y. J.; Russell, C. T.; Nagy, A. F.; Toth, G.; Halekas, J. S.; Connerney, J. E. P.; Espley, J. R.; Mahaffy, P. R.

    2015-01-01

    The crustal remnant field on Mars rotates constantly with the planet, varying the magnetic field configuration interacting with the solar wind. It has been found that ion loss rates slowly vary with the subsolar longitude, anticorrelating with the intensity of the dayside crustal field source, with some time delay, using a time-dependent multispecies MHD model. In this study, we investigate in detail how plasma properties are influenced locally by the crustal field and its rotation. Model results will be compared in detail with plasma observations from MAVEN.

  11. Modelling the solar wind interaction with Mercury by a quasi-neutral hybrid model

    Directory of Open Access Journals (Sweden)

    E. Kallio

    Full Text Available Quasi-neutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physics research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as the effects associated with the ions’ finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasi-neutral hybrid models have been used to study the solar wind interaction with the non-magnetised Solar System bodies of Mars, Venus, Titan and comets. Localized, two-dimensional hybrid model runs have also been made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasi-neutral hybrid model.

    In this paper we present a new quasi-neutral hybrid model developed to study various processes associated with the Mercury-solar wind interaction. Emphasis is placed on addressing advantages and disadvantages of the approach to study different plasma physical processes near the planet. The basic assumptions of the approach and the algorithms used in the new model are thoroughly presented. Finally, some of the first three-dimensional hybrid model runs made for Mercury are presented.

    The resulting macroscopic plasma parameters and the morphology of the magnetic field demonstrate the applicability of the new approach to study the Mercury-solar wind interaction globally. In addition, the real advantage of the kinetic hybrid model approach is to study the property of individual ions, and the study clearly demonstrates the large potential of the approach to address these more detailed issues by a quasi-neutral hybrid model in the future.

    Key words. Magnetospheric physics

  12. Investigating Power System Primary and Secondary Reserve Interaction under High Wind Power Penetration

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yingchen [National Renewable Energy Lab. (NREL), Golden, CO (United States); Tan, Jin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Krad, Ibrahim [National Renewable Energy Lab. (NREL), Golden, CO (United States); Yang, Rui [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ela, Erik [Electric Power Research Inst. (EPRI), Knoxville, TN (United States)

    2016-12-01

    Power system frequency needs to be maintained close to its nominal value at all times to successfully balance load and generation and maintain system reliability. Adequate primary frequency response and secondary frequency response are the primary forces to correct an energy imbalance at the second-to-minute level. As wind energy becomes a larger portion of the world's energy portfolio, there is an increased need for wind to provide frequency response. This paper addresses one of the major concerns about using wind for frequency regulation: the unknown factor of the interaction between primary and secondary reserves. The lack of a commercially available tool to model this has limited the energy industry's understanding of when the depletion of primary reserves will impact the performance of secondary response or vice versa. This paper investigates the issue by developing a multi-area frequency response integration tool with combined primary and secondary capabilities. The simulation is conducted in close coordination with economical energy scheduling scenarios to ensure credible simulation results.

  13. Interactions of mineral dust with pollution and clouds: An individual-particle TEM study of atmospheric aerosol from Saudi Arabia

    Science.gov (United States)

    Pósfai, Mihály; Axisa, Duncan; Tompa, Éva; Freney, Evelyn; Bruintjes, Roelof; Buseck, Peter R.

    2013-03-01

    Aerosol particles from desert dust interact with clouds and influence climate on regional and global scales. The Riyadh (Saudi Arabia) aerosol campaign was initiated to study the effects of dust particles on cloud droplet nucleation and cloud properties. Here we report the results of individual-particle studies of samples that were collected from an aircraft in April 2007. We used analytical transmission electron microscopy, including energy-dispersive X-ray spectrometry, electron diffraction, and imaging techniques for the morphological, chemical, and structural characterization of the particles. Dust storms and regional background conditions were encountered during four days of sampling. Under dusty conditions, the coarse (supermicrometer) fraction resembles freshly crushed rock. The particles are almost exclusively mineral dust grains and include common rock-forming minerals, among which clay minerals, particularly smectites, are most abundant. Unaltered calcite grains also occur, indicating no significant atmospheric processing. The particles have no visible coatings but some contain traces of sulfur. The fine (submicrometer) fraction is dominated by particles of anthropogenic origin, primarily ammonium sulfate (with variable organic coating and some with soot inclusions) and combustion-derived particles (mostly soot). In addition, submicrometer, iron-bearing clay particles also occur, many of which are internally mixed with ammonium sulfate, soot, or both. We studied the relationships between the properties of the aerosol and the droplet microphysics of cumulus clouds that formed above the aerosol layer. Under dusty conditions, when a large concentration of coarse-fraction mineral particles was in the aerosol, cloud drop concentrations were lower and droplet diameters larger than under regional background conditions, when the aerosol was dominated by submicrometer sulfate particles.

  14. SparkSeq: fast, scalable and cloud-ready tool for the interactive genomic data analysis with nucleotide precision.

    Science.gov (United States)

    Wiewiórka, Marek S; Messina, Antonio; Pacholewska, Alicja; Maffioletti, Sergio; Gawrysiak, Piotr; Okoniewski, Michał J

    2014-09-15

    Many time-consuming analyses of next -: generation sequencing data can be addressed with modern cloud computing. The Apache Hadoop-based solutions have become popular in genomics BECAUSE OF: their scalability in a cloud infrastructure. So far, most of these tools have been used for batch data processing rather than interactive data querying. The SparkSeq software has been created to take advantage of a new MapReduce framework, Apache Spark, for next-generation sequencing data. SparkSeq is a general-purpose, flexible and easily extendable library for genomic cloud computing. It can be used to build genomic analysis pipelines in Scala and run them in an interactive way. SparkSeq opens up the possibility of customized ad hoc secondary analyses and iterative machine learning algorithms. This article demonstrates its scalability and overall fast performance by running the analyses of sequencing datasets. Tests of SparkSeq also prove that the use of cache and HDFS block size can be tuned for the optimal performance on multiple worker nodes. Available under open source Apache 2.0 license: https://bitbucket.org/mwiewiorka/sparkseq/. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. Interactive Classification of Construction Materials: Feedback Driven Framework for Annotation and Analysis of 3d Point Clouds

    Science.gov (United States)

    Hess, M. R.; Petrovic, V.; Kuester, F.

    2017-08-01

    Digital documentation of cultural heritage structures is increasingly more common through the application of different imaging techniques. Many works have focused on the application of laser scanning and photogrammetry techniques for the acquisition of threedimensional (3D) geometry detailing cultural heritage sites and structures. With an abundance of these 3D data assets, there must be a digital environment where these data can be visualized and analyzed. Presented here is a feedback driven visualization framework that seamlessly enables interactive exploration and manipulation of massive point cloud data. The focus of this work is on the classification of different building materials with the goal of building more accurate as-built information models of historical structures. User defined functions have been tested within the interactive point cloud visualization framework to evaluate automated and semi-automated classification of 3D point data. These functions include decisions based on observed color, laser intensity, normal vector or local surface geometry. Multiple case studies are presented here to demonstrate the flexibility and utility of the presented point cloud visualization framework to achieve classification objectives.

  16. Relevance of wildfires on dust emissions via interaction with near-surface wind pattern

    Science.gov (United States)

    Wagner, Robert; Jähn, Michael; Schepanski, Kerstin

    2017-04-01

    Mineral dust is a key player in the Earth system and shows diverse impacts on the radiation budget, cloud microphysics, marine and terrestrial ecosystems. Eventually, it also affects our modern way of life. Not only dust emissions from barren or unvegetated soil surfaces like deserts or uncultivated croplands are important sources of airborne mineral dust. Also, during fire events dust is entrained into the atmosphere and appears to contribute noteworthy to the atmospheric dust burden. The underlying process, which drives dust entrainment during fires, is the so-called pyro-convection. The high temperatures in the center of a fire result in an upward motion of the heated air. Subsequently, air flows towards the fire replacing the raising air. The resulting accelerated winds are able to mobilize soil and dust particles up to a size of several millimeters, depending of both the size and the strength of the fire. Several measurements have shown that up to 80% of the mass fraction of the emitted particles during natural or prescribed fires is related to soil or dust particles. The particles are then mixed externally with the combustion aerosols into the convective updraft and were finally inject into altitudes above the planetary boundary layer where they can be distributed and transported over long distances by the atmospheric circulation. To investigate the impacts of such fires on the near-surface wind pattern and the potential for dust emissions via exceeding typical threshold velocities, high resolved Large-Eddy Simulations (LES) with the All Scale Atmospheric Model (ASAM) were executed. In the framework of this study, the influences of different fire properties (fire intensity, size, and shape) and different atmospheric conditions on the strength and extent of fire-related winds and finally their relevance for dust emissions were investigated using sensitivity studies. Prescribed fires are omnipresent during dry seasons and pyro-convection is a mechanism

  17. An interactive mapping tool for visualizing lacunarity of laser scanned point clouds

    Science.gov (United States)

    Kania, Adam; Székely, Balázs

    2016-04-01

    Lacunarity, a measure of the spatial distribution of the empty space in a certain model or real space over large spatial scales, is found to be a useful descriptive quantity in many fields using imagery, including, among others, geology, dentistry, neurology. Its application in ecology was suggested more than 20 years ago. The main problem of its application was the lack of appropriate high resolution data. Nowadays, full-waveform laser scanning, also known as FWF LiDAR, provides the tool for mapping the vegetation in unprecedented details and accuracy. Consequently, the lacunarity concept can be revitalized, in order to study the structure of the vegetation in this sense as well. Calculation of lacunarity, even if it is done in two dimensions (2D), is still has its problems: on one hand it is a number-crunching procedure, on the other hand, it produces 4D results: at each 3D point it returns a set of data that are function of scale. These data sets are difficult to visualize, to evaluate, and to compare. In order to solve this problem, an interactive mapping tool has been conceptualized that is designed to manipulate and visualize the data, lets the user set parameters for best visualization or comparison results. The system is able to load large amounts of data, visualize them as lacunarity curves, or map view as horizontal slices or in 3D point clouds coloured according to the user's choice. Lacunarity maps are presented as a series of (usually) horizontal profiles, e.g. rasters, which cells contain color-mapped values of selected lacunarity of the point cloud. As lacunarity is usually analysed in a series of successive windows sizes, the tool can show a series of rasters with sequentially animated lacunarity maps calculated for various window sizes. A very fast switching of colour schemes is possible to facilitate rapid visual feedback to better understand underlying data patterns exposed by lacunarity functions. In the comparison mode, two sites (or two areas

  18. Analysis of the Interaction and Transport of Aerosols with Cloud or Fog during Dragon Campaigns from Aeronet and Satellite Remote Sensing

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Schafer, J.; Giles, D. M.; Kim, J.; Kim, Y. J.; Sano, I.; Lynch, P.; Pickering, K. E.; Crawford, J. H.; Sinyuk, A.; Smirnov, A.; Trevino, N.

    2014-12-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Recent major DRAGON field campaigns in Japan and South Korea (Spring 2012) and California (Winter 2013) have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth signal for these cases of persistent and extensive cloud cover. Satellite retrievals of AOD from MODIS sensors were also investigated to assess the issue of detectability of high AOD events associated with high cloud fraction. AERONET is updating the cloud-screening algorithm applied to AOD data in the upcoming Version 3 database. Comparisons of cloud screening from Versions 2 and 3 of cases with high AOD associated with clouds will be studied. Additionally, extensive fog that was coincident with aerosol layer height on some days in both Korea and California resulted in large increases in fine mode aerosol radius, with a mode of cloud-processed or residual aerosol of radius ~0.4-0.5 micron sometimes observed. Cloud processed aerosol may occur much more frequently than AERONET

  19. Hydrodynamic simulations of mechanical stellar feedback in a molecular cloud formed by thermal instability

    Science.gov (United States)

    Wareing, C. J.; Pittard, J. M.; Falle, S. A. E. G.

    2017-09-01

    We have used the AMR hydrodynamic code, mg, to perform 3D hydrodynamic simulations with self-gravity of stellar feedback in a spherical clumpy molecular cloud formed through the action of thermal instability. We simulate the interaction of the mechanical energy input from 15, 40, 60 and 120 M⊙ stars into a 100 pc diameter 16 500 M⊙ cloud with a roughly spherical morphology with randomly distributed high-density condensations. The stellar winds are introduced using appropriate non-rotating Geneva stellar evolution models. In the 15 M⊙ star case, the wind has very little effect, spreading around a few neighbouring clumps before becoming overwhelmed by the cloud collapse. In contrast, in the 40, 60 and 120 M⊙ star cases, the more powerful stellar winds create large cavities and carve channels through the cloud, breaking out into the surrounding tenuous medium during the wind phase and considerably altering the cloud structure. After 4.97, 3.97 and 3.01 Myr, respectively, the massive stars explode as supernovae (SNe). The wind-sculpted surroundings considerably affect the evolution of these SN events as they both escape the cloud along wind-carved channels and sweep up remaining clumps of cloud/wind material. The 'cloud' as a coherent structure does not survive the SN from any of these stars, but only in the 120 M⊙ case is the cold molecular material completely destabilized and returned to the unstable thermal phase. In the 40 and 60 M⊙ cases, coherent clumps of cold material are ejected from the cloud by the SN, potentially capable of further star formation.

  20. Submillimetre molecular line observations of M17: The interaction of an ionisation front and molecular clouds

    Science.gov (United States)

    Rainey, R.; White, G. J.; Gatley, I.; Hayashi, S. S.; Kaifu, N.; Griffin, M. J.; Monteiro, S.; Cronin, N. J.; Scivetti, A.

    1986-01-01

    An area of about 9 by 10 arc minutes in the M17 molecular cloud has been mapped in the J=3-2 transition of CO. The strongest CO emission is observed to come from the two bars to the north and southwest, which lie just outside the area of ionized gas seen in the radio continuum studies. We are viewing the boundary between the ionized and molecular gas almost edge on. The most intense CO emission is from the area around the dense molecular cloud core M17SW in the southwest bar. To the east of M17SW there are signs of recent or continuing star formation including H2O masers and an ultra-compact HII region. The CO J=3-2 spectra observed are complex with considerable variation in line shapes occuring over distances of less than one arc minute. We interpret the velocity structure of this region as arising from an ensemble of molecular cloud fragments in addition to extended emission. We have identified several cloud components at different velocities within both the northern and southwest bars of CO emission. A simple kinematic model of the cloud components in the southwest bar in which they are considered to be clumps of post-shock gas lying close to the edge of the expanding HII region, with the shock being driven by Kleinmann's star, gives a velocity of approx. 10.8 km s(-1) for the expansion velocity of the HII region, which is currently at a distance of approx. 2.4 pc from Kleinmann's star. The resulting shock is thought to be preceding the ionisation front and appears to have led to the fragmentation of the original cloud.

  1. Solar wind interaction with the Martian upper atmosphere: Crustal field orientation, solar cycle, and seasonal variations

    Science.gov (United States)

    Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Toth, Gabor; Lee, Yuni; Nagy, Andrew F.; Tenishev, Valeriy; Pawlowski, Dave J.; Combi, Michael R.; Najib, Dalal

    2015-09-01

    A comprehensive study of the solar wind interaction with the Martian upper atmosphere is presented. Three global models: the 3-D Mars multifluid Block Adaptive Tree Solar-wind Roe Upwind Scheme MHD code (MF-MHD), the 3-D Mars Global Ionosphere Thermosphere Model (M-GITM), and the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M-AMPS) were used in this study. These models are one-way coupled; i.e., the MF-MHD model uses the 3-D neutral inputs from M-GITM and the 3-D hot oxygen corona distribution from M-AMPS. By adopting this one-way coupling approach, the Martian upper atmosphere ion escape rates are investigated in detail with the combined variations of crustal field orientation, solar cycle, and Martian seasonal conditions. The calculated ion escape rates are compared with Mars Express observational data and show reasonable agreement. The variations in solar cycles and seasons can affect the ion loss by a factor of ˜3.3 and ˜1.3, respectively. The crustal magnetic field has a shielding effect to protect Mars from solar wind interaction, and this effect is the strongest for perihelion conditions, with the crustal field facing the Sun. Furthermore, the fraction of cold escaping heavy ionospheric molecular ions [(O2+ and/or O2+)/Total] are inversely proportional to the fraction of the escaping (ionospheric and corona) atomic ion [O+/Total], whereas O2+ and O2+ ion escape fractions show a positive linear correlation since both ion species are ionospheric ions that follow the same escaping path.

  2. Interstellar clouds in high-speed, supersonic flows: Two-dimensional simulations

    Science.gov (United States)

    Schiano, A. V. R.; Christiansen, Wayne A.; Knerr, Jeffrey M.

    1995-01-01

    We present a series of gasdynamical simulations of the interaction of a dense, cool interstellar cloud with a high-speed, supersonic wind that confines and accelerates the embedded cloud. Our goal is to attempt to determine if such clouds can survive various potentially disruptive instabilities, that occur at their peripheries, long enough to be accelerated to speeds which are comparable to the wind velocity. These simulations are performed using two-dimensional, Eulerian gas dynamics on both an axisymmetric (about the cloud axis) and 'slab' geometric grid. The spatial and temporal resolutions of the simulations are varied over a wide range to investigate the effects of small-scale instabilities on the overall acceleration of clouds and the development of large-scale, disruptive instabilities. Also, we study the effects of wind/cloud Mach number variations by changing the wind speed constant at about 12 km/s (which corresponds to a cloud temperature of 10,000 K). The current simulations track the evolution of clouds as they are accelerated to speeds approximately 4-5 times greater than their internal sound speeds. Furthermore, the models with the highest resolution were extended far beyond quasi-linear Rayleigh-Taylor growth times reaching 6-7 Rayleigh-Taylor growth times for the largest scale instabilities before being terminated because of the accumulation of errors at the rear grid boundary.

  3. Wind Power Plant Market and Operation Interaction. Principles for Information and Energy Management Systems

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Joergen; Karlsson, Per [Lund Univ., (Sweden). Dept. of Industrial Electrical Engineering and Automation; Johnsson, Anders [Vattenfall Utveckling AB, Stockholm (Sweden)

    2003-11-01

    This paper specifies principle structures for energy management system (EMS) and information enabling market-based operation of wind power plants (WPP). The structure provides the means for condensing the necessary information for future needs and demands on operation of new large WPP. New technical solutions for wind power give the possibility to provide a number of services to energy market actors such as energy and ancillary services to the power system. The structure should facilitate the expansion of new WPP, where a new WPP should be possible to connect to an existing structure and then automatically adapt to the system. If real-time trading and operation may become reality, the management mechanism from contract to physical power transaction might get faster and become an important advantage for generating units based on renewals. The automated process puts demands on the interface for both market interaction and operation interaction with the market actors. Uniform information structures and communication interfaces and automation of functions for market management, planning and production control are one step towards a 'plug-and-produce' solution.

  4. Remnant magnetic fields of Mars and their interaction with the solar wind

    Science.gov (United States)

    Breus, T. K.; Krymskii, A. M.

    2017-07-01

    This work presents a review of studies of the Martian magnetic fields during the early Soviet missions to Mars in 1971-1974, which never approached Mars by closer than 1000 km before the experiment with the Magnetometer/Electronic Reflectometer (MAG/ER) on board the Mars Global Surveyor spacecraft, which could descend to altitudes of 80-100 km. At present, the experiment with the magnetometer (MAG) onboard the American MAVEN spacecraft adds new data, but the map of distribution of remnant magnetic fields of Mars and the picture of their interaction with the solar wind are already formed and, at its core, obviously, will not be revised. Thus, it would be very instructive to consider the following in detail: (a) what is already known regarding the features and distribution of remnant magnetic fields on Mars; (b) how they control the interaction of solar wind with a weakly magnetized planet (Mars); and (c) what is its distinction from another nonmagnetized planet (Venus).

  5. A Multiple-Antenna System for ISM-Band Transmission

    Directory of Open Access Journals (Sweden)

    Rinas J

    2004-01-01

    Full Text Available We present a multiple antenna system for industrial, scientific, and medical (ISM-band transmission (MASI. The hardware demonstrator was developed and realized at our institute. It enables multiple-input multiple-output (MIMO-communication applications and is capable of transmiting arbitrary signals using transmit and receive antennas in parallel. It operates in the 2.4 GHz ISM-band. The hardware concept is introduced and some design specifications are discussed. Using this transmission system, we present some measurement results to show the feasibility of MIMO concepts currently under discussion. The applications include transmit and receive diversity for single carrier and OFDM as well as blind source separation (BSS techniques.

  6. Interaction of Solar Wind and Magnetic Anomalies - Modelling from Moon to Mars

    Science.gov (United States)

    Alho, Markku; Kallio, Esa; Wedlund, Cyril Simon; Wurz, Peter

    2015-04-01

    The crustal magnetic anomalies on both the Moon and Mars strongly affect the local plasma environment. On the Moon, the impinging solar wind is decelerated or deflected when interacting with the magnetic field anomaly, visible in the lunar surface as energetic neutral atom (ENA) emissions or as reflected protons, and may play a part in the space weathering of the lunar soil. At Mars, the crustal magnetic fields have been shown to be associated with, e.g., enhanced electron scale heights and modified convection of ionospheric plasma, resulting in the plasma environment being dominated by crustal magnetic fields up to altitudes of 400km. Our previous modelling work suggested that Hall currents are a dominant feature in a Moon-like magnetic anomaly interaction at scales at or below the proton inertial length. In this work we study the solar wind interaction with magnetic anomalies and compare the plasma environments of a Moon-like anomaly with a Mars-like anomaly by introducing an ionosphere and an exosphere to probe the transition from an atmosphere-less anomaly interaction to an ionospheric one. We utilize a 3D hybrid plasma model, in which ions are modelled as particles while electrons form a charge-neutralizing massless fluid. The hybrid model gives a full description of ion kinetics and associated plasma phenomena at the simulation region ranging from instabilities to possible reconnection. The model can thus be used to interpret both in-situ particle and field observations and remotely-sensed ENA emissions. A self-consistent ionosphere package for the model is additionally in development.

  7. Analysis of the Interaction and Transport of Aerosols with Cloud or Fog during DRAGON Campaigns in Asia from AERONET and Satellite Remote Sensing

    Science.gov (United States)

    Eck, Thomas; Holben, Brent; Reid, Jeffrey; Lynch, Peng; Schafer, Joel; Giles, David; Kim, Jhoon; Kim, Young; Sano, Itaru; Platnick, Steven; Arnold, George; Lyapustin, Alexei; Pickering, Kenneth; Crawford, James; Siniuk, Alexander; Smirnov, Alexander; Wang, Pucai; Xia, Xiangao; Li, Zhanqing

    2015-04-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Major DRAGON field campaigns in Japan and South Korea during Spring of 2012 have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth (AOD) signal from AERONET data for these cases of persistent and extensive cloud cover. Satellite retrievals of AOD from MODIS sensors (from both dark target and MAIAC algorithms) were also investigated to assess the issue of detectability of high AOD events associated with high cloud fraction. Cloud properties retrieved from MODIS are also investigated in relation to the AERONET and satellite measurements of AOD. Underestimation of AOD by the Navy Aerosol Analysis and Prediction System (NAAPS) model at very high AOD at sites in China and Korea was observed, especially for observations that are cloud screened by AERONET (L2 data). Additionally, extensive fog that was coincident with aerosol layer height on some days in Korea resulted in large increases in fine mode aerosol radius, with a mode of cloud

  8. Impact of Incremental Sampling Methodology (ISM) on Metals Bioavailability

    Science.gov (United States)

    2016-05-01

    Certification Program (ESTCP) funded ER-0918 project, which developed new sampling and sample preparation procedures falling under the ISM umbrella...2007; Rodriguez et al. 1999; Ruby et al. 1996, ERDC TR-16-4 4 1999) were conducted to assess the relative bioavailability (RBA) of metals in soil or...differences in digestion efficiencies (Rodriguez et al. 1999; Ruby et al. 1999, 1996). The bioavailable metal is typically only a fraction of the total

  9. Study on Risk of Enterprise' Technology Innovation Based on ISM

    Science.gov (United States)

    Li, Hongyan

    The risk in the process of enterprise' technology innovation is concluted five subsystems: environmental risk, market risk, enterprise capacity risk, project risk and project management risk, 16 risk factors under each subsystem are identified. A Interpretative Structural Modeling(ISM) of of risk factors is established, the relationship and influence levels of them is confirmed, the purpose is to help enterprise assessing risks and taking countermeasure to minimize the potential loss and increase the innovation income.

  10. Impact of Aerosol-Cloud Interactions on Local Meteorology and Air Quality - A Case Study of National Capital Region (NCR) of India

    Science.gov (United States)

    Gupta, M.; Mohan, M.

    2016-12-01

    Recent trend analysis of PM10 (Particulate Matter with size ≤ 10 micron) concentrations shows exceedance of the National Ambient Air Quality Standards (NAAQS) since 2001 in Delhi. Capital city of India, and surrounding regions.Even though O3 levels are generally below NAAQS, regular monitoring has revealed that they too have increased consistently by 6 µg m-3 from 2009 (35.3 µg m-3) to 2012 (41.5 µg m-3) which is a cause of alarm. This O3 build up is increasing the public health risk. In summer 2015, exceedance of O3 levels ranged from 92% - 97%. In order to implement air pollution control strategies it is important to understand the impact of meteorology on atmospheric pollutants and vice-versa. The regional air quality model WRF-Chem is ideally suited to study the feedback between air pollution and meteorology (Luo and Yu, 2011; Forkel et al., 2012; Zhang et al., 2014). Feedback effects can be specifically important during air pollution episodes that occur as a result of stagnation events, which are characterized by weak synoptic forcing of winds, which leads up to the buildup of pollutant concentrations close to emissions sources (Zhang et al., 2014). In present study, WRF-Chem model is implemented to understand the impact of meteorology on atmospheric chemistry of gaseous pollutants and aerosols and vice-versa for NCR for the month of June 2010 representing summer season. The study is performed by considering four scenarios (i) no feedback is considered (ii) only cumulus radiation feedback (iii) only aerosol-radiation feedback (i.e. the direct effect) and (iv) aerosol-radiation feedback along with cloud interactions (i.e direct effect + indirect effect) are taken into account. Significant changes in meteological and air quality fields have been observed with inclusion feedback mechanisms. Temperature difference of about -0.5 to -0.1 degrees was observed on inclusion of feedback interactions. Similarly a difference of 100 to 150 W m-2 was noted in Shortwave

  11. Neutral ISM, Lyα, and Lyman-continuum in the Nearby Starburst Haro11

    Science.gov (United States)

    Rivera-Thorsen, T. Emil; Östlin, Göran; Hayes, Matthew; Puschnig, Johannes

    2017-03-01

    Star-forming galaxies are believed to be a major source of Lyman continuum (LyC) radiation responsible for reionizing the early universe. Direct observations of escaping ionizing radiation have however been sparse and with low escape fractions. In the local universe, only 10 emitters have been observed, with typical escape fractions of a few percent. The mechanisms regulating this escape need to be strongly evolving with redshift in order to account for the epoch of reionization. Gas content and star formation feedback are among the main suspects, known to both regulate neutral gas coverage and evolve with cosmic time. In this paper, we reanalyze Hubble Space Telescope (HST)-Cosmic Origins Spectrograph (COS) spectrocopy of the first detected local LyC leaker, Haro 11. We examine the connection between LyC leakage and Lyα line shape, and feedback-influenced neutral interstellar medium (ISM) properties like kinematics and gas distribution. We discuss the two extremes of an optically thin, density bounded ISM and a riddled, optically thick, ionization bounded ISM, and how Haro 11 fits into theoretical predictions. We find that the most likely ISM model is a clumpy neutral medium embedded in a highly ionized medium with a combined covering fraction of unity and a residual neutral gas column density in the ionized medium high enough to be optically thick to Lyα, but low enough to be at least partly transparent to LyC and undetected in Si II. This suggests that star formation feedback and galaxy-scale interaction events play a major role in opening passageways for ionizing radiation through the neutral medium. Based on observations with HST-COS, program GO 13017, obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and

  12. Face-ism and Objectification in Mainstream and LGBT Magazines.

    Directory of Open Access Journals (Sweden)

    Nathan N Cheek

    Full Text Available In visual media, men are often shown with more facial prominence than women, a manifestation of sexism that has been labeled face-ism. The present research extended the study of facial prominence and gender representation in media to include magazines aimed at lesbian, gay, bisexual, and transgender (LGBT audiences for the first time, and also examined whether overall gender differences in facial prominence can still be found in mainstream magazines. Face-ism emerged in Newsweek, but not in Time, The Advocate, or Out. Although there were no overall differences in facial prominence between mainstream and LGBT magazines, there were differences in the facial prominence of men and women among the four magazines included in the present study. These results suggest that face-ism is still a problem, but that it may be restricted to certain magazines. Furthermore, future research may benefit from considering individual magazine titles rather than broader categories of magazines, given that the present study found few similarities between different magazines in the same media category--indeed, Out and Time were more similar to each other than they were to the other magazine in their respective categories.

  13. Lyman alpha and ISM Tomography of Haro 11

    Science.gov (United States)

    Oestlin, Goeran

    2017-08-01

    The compact starburst Haro11 is one of the nearest Lyman break analogs and the closest galaxy with a confirmed leakage of Lyman continuum photons. It is also one of the nearest Lyman alpha emitting galaxies known. Haro11 has three bright emission knots (A,B and C). Knot C has previously been observed with COS. We have used absorption lines in these spectra to determine the covering fraction and velocity structure of the neutral and ionized gas along the line of sight, finding la wide range of outflow velocities and covering fractions, indicating the presence of an outflowing clumpy ISM. These are conditions that should be benign for the escape of Lyman continuum emission, but there are other observations suggesting that knot C may not be the cause of the Lyman continuum leakage: its ionization level is low, and there is no Lyman alpha at the systemic velocity which one would predict if Lyman continuum was escaping through a clumpy medium. We propose COS spectroscopy of the other two knots and two positions showing bright diffuse Lyman alpha emission. With multiple sightlines probing the ISM and Lyman alpha emission we can perform a spatially resolved tomographic study of the ISM and Lyman alpha emission in this key galaxy. By adding STIS spectroscopy, we propose to furthermore study these proceses at the finest scale offered by HST.

  14. Interactivity Technologies to Improve the Learning in Classrooms through the Cloud

    Science.gov (United States)

    Fardoun, Habib M.; Alghazzawi, Daniyal M.; Paules, Antonio

    2018-01-01

    In this paper, the authors present a cloud system that incorporate tools developed in HTML5 and JQuery technologies, which are offered to professors and students in the development of a teaching methodology called flipped classroom, where the theoretical content is usually delivered by video files and self-assessment tools that students can…

  15. Interaction of clouds, radiation, and the tropical warm pool sea surface temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, N.; Zhang, G.J.; Barnett, T.P.; Ramanathan, V. [Scripps Institution of Oceanography, La Jolla, CA (United States)] [and others

    1996-04-01

    The primary focus of this study is the Tropical Western Pacific (TWP). In this study, we combine in-situ observations Tropical Ocean Global Atmosphere [TOGA]-Coupled Ocean Atmosphere Response Experiment [COARE] and Central Equatorial Pacific Experiment [CEPEX] with satellite cloud data.

  16. Sensitivity of remote aerosol distributions to representation of cloud-aerosol interactions in a global climate model

    Science.gov (United States)

    Wang, H.; Easter, R. C.; Rasch, P. J.; Wang, M.; Liu, X.; Ghan, S. J.; Qian, Y.; Yoon, J.-H.; Ma, P.-L.; Vinoj, V.

    2013-06-01

    Many global aerosol and climate models, including the widely used Community Atmosphere Model version 5 (CAM5), have large biases in predicting aerosols in remote regions such as the upper troposphere and high latitudes. In this study, we conduct CAM5 sensitivity simulations to understand the role of key processes associated with aerosol transformation and wet removal affecting the vertical and horizontal long-range transport of aerosols to the remote regions. Improvements are made to processes that are currently not well represented in CAM5, which are guided by surface and aircraft measurements together with results from a multi-scale aerosol-climate model that explicitly represents convection and aerosol-cloud interactions at cloud-resolving scales. We pay particular attention to black carbon (BC) due to its importance in the Earth system and the availability of measurements. We introduce into CAM5 a new unified scheme for convective transport and aerosol wet removal with explicit aerosol activation above convective cloud base. This new implementation reduces the excessive BC aloft to better simulate observed BC profiles that show decreasing mixing ratios in the mid- to upper-troposphere. After implementing this new unified convective scheme, we examine wet removal of submicron aerosols that occurs primarily through cloud processes. The wet removal depends strongly on the subgrid-scale liquid cloud fraction and the rate of conversion of liquid water to precipitation. These processes lead to very strong wet removal of BC and other aerosols over mid- to high latitudes during winter months. With our improvements, the Arctic BC burden has a 10-fold (5-fold) increase in the winter (summer) months, resulting in a much-better simulation of the BC seasonal cycle as well. Arctic sulphate and other aerosol species also increase but to a lesser extent. An explicit treatment of BC aging with slower aging assumptions produces an additional 30-fold (5-fold) increase in the

  17. Evolution of the ISM at z < 1

    Science.gov (United States)

    Mohamed, Zaarah

    2014-01-01

    z=1 corresponds to a time at which the Universe was roughly half its current age, and is generally agreed to mark a shift in the typical processes involved in galaxy evolution. Galaxy interactions, merger rates, morphologies, and star formation rates (SFRs), for example, can all be said to have exhibited fundamental changes since z=1 (Combes et al. 2013). The underlying processes causing these changes, however, are not very well understood. Several studies (Combes et al. 2011; Combes et al. 2013; Daddi et al. 2010; Geach et al. 2011; Tacconi et al. 2010) have attempted to investigate the evolution of the molecular gas fraction and its influence upon the shift in SFR through CO line surveys . It is hypothesized that the molecular gas fraction should decrease over time as more of this gas is used to form stars. These studies, however, have only been conducted on very small samples, and many focus upon galaxies at specific redshifts or upon very luminous galaxies. It is thus increasingly difficult to discern whether or not the trends indicated by the composite of these studies represent real and definitive relationships concerning the evolution of the molecular gas fraction in “the average galaxy.” In addition, direct CO(1-->0) measurements are generally not possible for redshift ranges ~0.3-1 due to issues of instrument sensitivity and spectral coverage. This research attempts to re-examine the evolution of the molecular gas fraction at zinfluence of the evolution of the molecular gas fraction upon the evolution of SFRs. This involves fitting SEDs in order to determine dust masses and using a constant factor to convert these dust masses to molecular gas masses. Results are compared to previous literature and the expected trend (i.e., increase in SFR and in molecular gas fraction with increase in z). Suggestions for future evaluation and potential future applications of this method of estimating molecular gas masses are also discussed.

  18. Evolution of trace elements in the planetary boundary layer in southern China: Effects of dust storms and aerosol-cloud interactions

    Science.gov (United States)

    Li, Tao; Wang, Yan; Zhou, Jie; Wang, Tao; Ding, Aijun; Nie, Wei; Xue, Likun; Wang, Xinfeng; Wang, Wenxing

    2017-03-01

    Aerosols and cloud water were analyzed at a mountaintop in the planetary boundary layer in southern China during March-May 2009, when two Asian dust storms occurred, to investigate the effects of aerosol-cloud interactions (ACIs) on chemical evolution of atmospheric trace elements. Fe, Al, and Zn predominated in both coarse and fine aerosols, followed by high concentrations of toxic Pb, As, and Cd. Most of these aerosol trace elements, which were affected by dust storms, exhibited various increases in concentrations but consistent decreases in solubility. Zn, Fe, Al, and Pb were the most abundant trace elements in cloud water. The trace element concentrations exhibited logarithmic inverse relationships with the cloud liquid water content and were found highly pH dependent with minimum concentrations at the threshold of pH 5.0. The calculation of Visual MINTEQ model showed that 80.7-96.3% of Fe(II), Zn(II), Pb(II), and Cu(II) existed in divalent free ions, while 71.7% of Fe(III) and 71.5% of Al(III) were complexed by oxalate and fluoride, respectively. ACIs could markedly change the speciation distributions of trace elements in cloud water by pH modification. The in-cloud scavenging of aerosol trace elements likely reached a peak after the first 2-3 h of cloud processing, with scavenging ratios between 0.12 for Cr and 0.57 for Pb. The increases of the trace element solubility (4-33%) were determined in both in-cloud aerosols and postcloud aerosols. These results indicated the significant importance of aerosol-cloud interactions to the evolution of trace elements during the first several cloud condensation/evaporation cycles.

  19. SPACCIM simulations of chemical aerosol-cloud interactions with the multiphase chemical mechanism MCM-CAPRAM3.0i

    Science.gov (United States)

    Tilgner, A.; Schrödner, R.; Bräuer, P.; Wolke, R.; Herrmann, H.

    2010-07-01

    Heterogeneous and multiphase processes in fog droplets, cloud droplets and deliquescent particles can potentially alter the physico-chemical composition of the tropospheric aerosol on global scale. In order to model such complex tropospheric multiphase chemical interactions of clouds, fogs and deliquescent aerosol particles, chemical mechanisms with a detailed description of chemical processes in both the gas and aqueous phase are required. Currently, both near-explicit gas and aqueous phase mechanisms are available. However, a near-explicit chemical multiphase mechanism was still missing. Therefore, the near-explicit chemical gas phase mechanism MCM v3 (Master Chemical Mechanism, Saunder et al., 2003) with about 13502 reactions and the explicit aqueous phase mechanism CAPRAM3.0i (Chemical Aqueous Phase Radical Mechanism, Herrmann et al., 2005) with about 777 reactions were coupled and integrated into the model framework SPACCIM (SPectral Aerosol Cloud Chemistry Interaction Model; Wolke et al., 2005). The parcel model SPACCIM combines a complex microphysical and multiphase chemistry model. First SPACCIM simulations have been carried out for different environmental conditions using a non-permanent cloud scenario. The model studies were aimed to investigate multiphase chemistry in tropospheric deliquescent aerosol particles, fogs and clouds in more detail. The model investigations were focused on the multiphase chemistry of tropospheric radical oxidants such as OH and NO3, organic compounds and closely linked chemical subsystems. The model results have been analysed including time-resolved reaction flux analyses. The obtained model results of the near-explicit multiphase mechanism MCM-CAPRAM3.0i have been compared with results of former model studies using the non-explicit gas phase mechanism RACM-MIM2ext and CAPRAM3.0i (Tilgner and Herrmann, 2010). Herrmann, H., Tilgner, A., Barzaghi, P., Majdik, Z., Gligorovski, S., Poulain, L., and Monod, A.: Towards a more

  20. The effect of wave-particle interactions on the polar wind: Preliminary results

    Science.gov (United States)

    Barakat, A. R.; Barghouthi, I. A.

    1994-11-01

    A Monte Carlo simulation was developed in order to study the effects of wave-particle interactions (WPI) on the plasma outflow in the polar wind. The simulation also considered the other mechanisms included in the `classical' polar wind studies such as gravity, the polarization electrostatic field, and the divergence of geomagnetic field lines. Although the plasma consisted of electrons, H(+) and O(+) ions, we emphasized the behavior of H(+) in this preliminary study. The ion distribution function, as well as the profiles of its moments (density, drift velocity, temperatures, etc.) were found for different levels of WPI, that is, for different values of normalized diffusion rates in the velocity space (normalized D(sub perpendicular) H(+)). We found that as the WPI strength increases: (1) the ion drift velocity increases and its density decreases; (2) the perpendicular temperature T(sub perpendicular) (H(+)) increases; (3) the parallel temperature T(sub parallel) (H(+)) first decreases and then increases due to the balance between the parallel adiabatic cooling and the transfer of the energy from the perpendicular to the parallel direction; and (4) the temperature anisotropy ((T(sub parallel) (H(+))/T(sub perpendicular) (H(+)) is reduced and even reversed in some cases. For strong WPI (normalized D(sub perpendicular) (H(+) much greater than 1), the ion distribution function shows weak conic features at high altitudes.

  1. The effect of wave-particle interactions on the polar wind: Preliminary results

    Science.gov (United States)

    Barakat, A. R.; Barghouthi, I. A.

    1994-01-01

    A Monte Carlo simulation was developed in order to study the effects of wave-particle interactions (WPI) on the plasma outflow in the polar wind. The simulation also considered the other mechanisms included in the `classical' polar wind studies such as gravity, the polarization electrostatic field, and the divergence of geomagnetic field lines. Although the plasma consisted of electrons, H(+) and O(+) ions, we emphasized the behavior of H(+) in this preliminary study. The ion distribution function, as well as the profiles of its moments (density, drift velocity, temperatures, etc.) were found for different levels of WPI, that is, for different values of normalized diffusion rates in the velocity space (normalized D(sub perpendicular) H(+)). We found that as the WPI strength increases: (1) the ion drift velocity increases and its density decreases; (2) the perpendicular temperature T(sub perpendicular) (H(+)) increases; (3) the parallel temperature T(sub parallel) (H(+)) first decreases and then increases due to the balance between the parallel adiabatic cooling and the transfer of the energy from the perpendicular to the parallel direction; and (4) the temperature anisotropy ((T(sub parallel) (H(+))/T(sub perpendicular) (H(+)) is reduced and even reversed in some cases. For strong WPI (normalized D(sub perpendicular) (H(+) much greater than 1), the ion distribution function shows weak conic features at high altitudes.

  2. Multiple tuned mass damper based vibration mitigation of offshore wind turbine considering soil-structure interaction

    Science.gov (United States)

    Hussan, Mosaruf; Sharmin, Faria; Kim, Dookie

    2017-08-01

    The dynamics of jacket supported offshore wind turbine (OWT) in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction (SSI) is a fundamental principle to analyze stability and safety of the structure. This study focuses on the performance of the multiple tuned mass damper (MTMD) in minimizing the dynamic responses of the structures objected to seismic loads combined with static wind and wave loads. Response surface methodology (RSM) has been applied to design the MTMD parameters. The analyses have been performed under two different boundary conditions: fixed base (without SSI) and flexible base (with SSI). Two vibration modes of the structure have been suppressed by multi-mode vibration control principle in both cases. The effectiveness of the MTMD in reducing the dynamic response of the structure is presented. The dynamic SSI plays an important role in the seismic behavior of the jacket supported OWT, especially resting on the soft soil deposit. Finally, it shows that excluding the SSI effect could be the reason of overestimating the MTMD performance.

  3. Two-way Fluid-Structure Interaction Simulation of a Micro Horizontal Axis Wind Turbine

    Directory of Open Access Journals (Sweden)

    Yi-Bao Chen

    2015-01-01

    Full Text Available A two-way Fluid-Structure Interaction (FSI analyses performed on a micro horizontal axis wind turbine (HAWT which coupled the CFX solver with Structural solver in ANSYS Workbench was conducted in this paper. The partitioned approach-based non-conforming mesh methods and the k-ε turbulence model were adopted to perform the study. Both the results of one-way and two-way FSI analyses were presented and compared with each other, and discrepancy of the results, especially the mechanical properties, were analysed. Grid convergence which is crucial to the results was performed, and the relationship between the inner flow field domain (rotational domain and the number of grids (number of cells, elements was verified for the first time. Dynamical analyses of the wind turbine were conducted using the torque as a reference value, to verify the rationality of the model which dominates the accuracy of results. The optimal case was verified and used to conduct the study, thus, the results derived from the simulation of the FSI are accurate and credible.

  4. Determining Best Estimates and Uncertainties in Cloud Microphysical Parameters from ARM Field Data: Implications for Models, Retrieval Schemes and Aerosol-Cloud-Radiation Interactions

    Energy Technology Data Exchange (ETDEWEB)

    McFarquhar, Greg [Univ. of Illinois, Urbana, IL (United States)

    2015-12-28

    We proposed to analyze in-situ cloud data collected during ARM/ASR field campaigns to create databases of cloud microphysical properties and their uncertainties as needed for the development of improved cloud parameterizations for models and remote sensing retrievals, and for evaluation of model simulations and retrievals. In particular, we proposed to analyze data collected over the Southern Great Plains (SGP) during the Mid-latitude Continental Convective Clouds Experiment (MC3E), the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX), the Small Particles in Cirrus (SPARTICUS) Experiment and the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign, over the North Slope of Alaska during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) and the Mixed-Phase Arctic Cloud Experiment (M-PACE), and over the Tropical Western Pacific (TWP) during The Tropical Warm Pool International Cloud Experiment (TWP-ICE), to meet the following 3 objectives; derive statistical databases of single ice particle properties (aspect ratio AR, dominant habit, mass, projected area) and distributions of ice crystals (size distributions SDs, mass-dimension m-D, area-dimension A-D relations, mass-weighted fall speeds, single-scattering properties, total concentrations N, ice mass contents IWC), complete with uncertainty estimates; assess processes by which aerosols modulate cloud properties in arctic stratus and mid-latitude cumuli, and quantify aerosol’s influence in context of varying meteorological and surface conditions; and determine how ice cloud microphysical, single-scattering and fall-out properties and contributions of small ice crystals to such properties vary according to location, environment, surface, meteorological and aerosol conditions, and develop parameterizations of such effects.In this report we describe the accomplishments that we made on all 3 research objectives.

  5. Impacts of coastal upwelling off east Vietnam on the regional winds system: An air-sea-land interaction

    Science.gov (United States)

    Zheng, Zhe-Wen; Zheng, Quanan; Kuo, Yi-Chun; Gopalakrishnan, Ganesh; Lee, Chia-Ying; Ho, Chung-Ru; Kuo, Nan-Jung; Huang, Shih-Jen

    2016-12-01

    In this study, we analyze the influence of coastal upwelling off southeast Vietnam (CUEV) on local wind field using numerical simulations based on atmospheric model of Weather Research and Forecasting (WRF). Several scenarios are simulated by forcing identical model configurations with different SST fields. Based on simulation results, the relationship between CUEV and reduction of wind forcing is numerically evidenced. With the influence of a typical cold patch with a temperature drop of 3-5 °C, the local wind speeds can drop to less than 70% of original level. We find that the mechanism of response of the wind reduction to CUEV is enhancement of sea-breeze induced wind modulation. Onshore sea-breeze will enhance, while the contrast between land and sea is even more striking due to the contribution of a distinct coastal upwelling. This implies that air-sea-land interaction dominates the process of local wind system modulation in response to transient CUEV. This result sheds a new light on the air-sea interaction process within the SCS basin.

  6. Solar Wind Interaction with the Martian Upper Atmosphere at Early Mars/Extreme Solar Conditions

    Science.gov (United States)

    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Combi, M. R.

    2014-12-01

    The investigation of ion escape fluxes from Mars, resulting from the solar wind interaction with its upper atmosphere/ionosphere, is important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0 ~ 300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100 km ~ 5 RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model output fields into the 3-D BATS-R-US Mars multi-fluid MHD (MF-MHD) model (100 km ~ 20 RM) that can simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid MHD model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres. This feature allows us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model output fields are used as the input for the multi-fluid MHD model and the M-GITM is used as input into the AMPS exosphere model. In this study, we present M-GITM, AMPS, and MF-MHD calculations (1-way coupled) for 2.5 GYA conditions and/or extreme solar conditions for present day Mars (high solar wind velocities, high solar wind dynamic pressure, and high solar irradiance conditions, etc.). Present day extreme conditions may result in MF-MHD outputs that are similar to 2.5 GYA cases. The crustal field orientations are also considered in this study. By comparing estimates of past ion escape rates with the current ion loss rates to be returned by the MAVEN spacecraft (2013-2016), we can better constrain the

  7. Interaction Between the Atmospheric Boundary Layer and Wind Energy: From Continental-Scale to Turbine-Scale

    Science.gov (United States)

    St. Martin, Clara Mae

    Wind turbines and groups of wind turbines, or "wind plants", interact with the complex and heterogeneous boundary layer of the atmosphere. We define the boundary layer as the portion of the atmosphere directly influenced by the surface, and this layer exhibits variability on a range of temporal and spatial scales. While early developments in wind energy could ignore some of this variability, recent work demonstrates that improved understanding of atmosphere-turbine interactions leads to the discovery of new ways to approach turbine technology development as well as processes such as performance validation and turbine operations. This interaction with the atmosphere occurs at several spatial and temporal scales from continental-scale to turbine-scale. Understanding atmospheric variability over continental-scales and across plants can facilitate reliance on wind energy as a baseload energy source on the electrical grid. On turbine scales, understanding the atmosphere's contribution to the variability in power production can improve the accuracy of power production estimates as we continue to implement more wind energy onto the grid. Wind speed and directional variability within a plant will affect wind turbine wakes within the plants and among neighboring plants, and a deeper knowledge of these variations can help mitigate effects of wakes and possibly even allow the manipulation of these wakes for increased production. Herein, I present the extent of my PhD work, in which I studied outstanding questions at these scales at the intersections of wind energy and atmospheric science. My work consists of four distinct projects. At the coarsest scales, I analyze the separation between wind plant sites needed for statistical independence in order to reduce variability for grid-integration of wind. At lower wind speeds, periods of unstable and more turbulent conditions produce more power than periods of stable and less turbulent conditions, while at wind speeds closer to

  8. Control System interaction in the VSC-HVDC Grid Connected Offshore Wind Power Plant

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm; Kocewiak, Łukasz Hubert; Hjerrild, Jesper

    2015-01-01

    or converter interaction studies have therefore become an important part of the system design studies of a high voltage alternating current (HVAC) grid connected OWPP. The voltage sourced converter high voltage direct current (VSC-HVDC) has become a preferred choice for grid connection of remotely located...... in the electrical system which is generally located within the wind turbine generator (WTG) controller bandwidth. Some of the negative impact of the existence of harmonic instability include (but not limited to) accelerated component ageing due to increased thermal stresses and loss of power production before...... the source of the instability has been identified and mitigation methods have been designed and implemented. This procedure is not straightforward and can have a long lead time. The harmonic instability can have severe economic consequences for the OWPP owner due to the large investment. Harmonic stability...

  9. Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 1. Executive summary

    Energy Technology Data Exchange (ETDEWEB)

    Wilreker, V.F.; Stiller, P.H.; Scott, G.W.; Kruse, V.J.; Smith, R.F.

    1984-02-01

    This report summarizes the primary results of a three-part study involving the effects of connecting a MOD-OA wind turbine generator to an isolated diesel power system. The subject utility is that owned and operated by the Block Island Power Company (BIPCO). The MOD-OA installation here was the third of four experimental nominal 200 kW wind turbines connected to various utilities under the Federal Wind Energy Program. The BIPCO installation was characterized by the highest wind energy penetration levels of four sites and, as such, was adjudged the best candidate for conducting the data acquisition and analysis effort that is the subject of this study. The three-phases of the study analysis address: (1) fuel displacement, (2) dynamic interaction, and (3) three modes of reactive power control. These analyses all have as their basis the results of the data acquisition program conducted during 1982 from February into April on Block Island, Rhode Island.

  10. An optimal control framework for dynamic induction control of wind farms and their interaction with the atmospheric boundary layer.

    Science.gov (United States)

    Munters, W; Meyers, J

    2017-04-13

    Complex turbine wake interactions play an important role in overall energy extraction in large wind farms. Current control strategies optimize individual turbine power, and lead to significant energy losses in wind farms compared with lone-standing wind turbines. In recent work, an optimal coordinated control framework was introduced (Goit & Meyers 2015 J. Fluid Mech.768, 5-50 (doi:10.1017/jfm.2015.70)). Here, we further elaborate on this framework, quantify the influence of optimization parameters and introduce new simulation results for which gains in power production of up to 21% are observed.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Authors.

  11. An optimal control framework for dynamic induction control of wind farms and their interaction with the atmospheric boundary layer

    Science.gov (United States)

    Munters, W.

    2017-01-01

    Complex turbine wake interactions play an important role in overall energy extraction in large wind farms. Current control strategies optimize individual turbine power, and lead to significant energy losses in wind farms compared with lone-standing wind turbines. In recent work, an optimal coordinated control framework was introduced (Goit & Meyers 2015 J. Fluid Mech. 768, 5–50 (doi:10.1017/jfm.2015.70)). Here, we further elaborate on this framework, quantify the influence of optimization parameters and introduce new simulation results for which gains in power production of up to 21% are observed. This article is part of the themed issue ‘Wind energy in complex terrains’. PMID:28265024

  12. An energy balance model exploration of the impacts of interactions between surface albedo, cloud cover and water vapor on polar amplification

    Science.gov (United States)

    Södergren, A. Helena; McDonald, Adrian J.; Bodeker, Gregory E.

    2017-11-01

    We examine the effects of non-linear interactions between surface albedo, water vapor and cloud cover (referred to as climate variables) on amplified warming of the polar regions, using a new energy balance model. Our simulations show that the sum of the contributions to surface temperature changes due to any variable considered in isolation is smaller than the temperature changes from coupled feedback simulations. This non-linearity is strongest when all three climate variables are allowed to interact. Surface albedo appears to be the strongest driver of this non-linear behavior, followed by water vapor and clouds. This is because increases in longwave radiation absorbed by the surface, related to increases in water vapor and clouds, and increases in surface absorbed shortwave radiation caused by a decrease in surface albedo, amplify each other. Furthermore, our results corroborate previous findings that while increases in cloud cover and water vapor, along with the greenhouse effect itself, warm the polar regions, water vapor also significantly warms equatorial regions, which reduces polar amplification. Changes in surface albedo drive large changes in absorption of incoming shortwave radiation, thereby enhancing surface warming. Unlike high latitudes, surface albedo change at low latitudes are more constrained. Interactions between surface albedo, water vapor and clouds drive larger increases in temperatures in the polar regions compared to low latitudes. This is in spite of the fact that, due to a forcing, cloud cover increases at high latitudes and decreases in low latitudes, and that water vapor significantly enhances warming at low latitudes.

  13. Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations

    Directory of Open Access Journals (Sweden)

    L. Guicking

    2010-04-01

    Full Text Available We investigate wave properties of low-frequency magnetic field fluctuations in Venus' solar wind interaction region based on the measurements made on board the Venus Express spacecraft. The orbit geometry is very suitable to investigate the fluctuations in Venus' low-altitude magnetosheath and mid-magnetotail and provides an opportunity for a comparative study of low-frequency waves at Venus and Mars. The spatial distributions of the wave properties, in particular in the dayside and nightside magnetosheath as well as in the tail and mantle region, are similar to observations at Mars. As both planets do not have a global magnetic field, the interaction process of the solar wind with both planets is similar and leads to similar instabilities and wave structures. We focus on the spatial distribution of the wave intensity of the fluctuating magnetic field and detect an enhancement of the intensity in the dayside magnetosheath and a strong decrease towards the terminator. For a detailed investigation of the intensity distribution we adopt an analytical streamline model to describe the plasma flow around Venus. This allows displaying the evolution of the intensity along different streamlines. It is assumed that the waves are generated in the vicinity of the bow shock and are convected downstream with the turbulent magnetosheath flow. However, neither the different Mach numbers upstream and downstream of the bow shock, nor the variation of the cross sectional area and the flow velocity along the streamlines play probably an important role in order to explain the observed concentration of wave intensity in the dayside magnetosheath and the decay towards the nightside magnetosheath. But, the concept of freely evolving or decaying turbulence is in good qualitative agreement with the observations, as we observe a power law decay of the intensity along the streamlines. The observations support the assumption of wave convection through the magnetosheath, but

  14. Fluid-structure interaction simulation of floating structures interacting with complex, large-scale ocean waves and atmospheric turbulence with application to floating offshore wind turbines

    Science.gov (United States)

    Calderer, Antoni; Guo, Xin; Shen, Lian; Sotiropoulos, Fotis

    2018-02-01

    We develop a numerical method for simulating coupled interactions of complex floating structures with large-scale ocean waves and atmospheric turbulence. We employ an efficient large-scale model to develop offshore wind and wave environmental conditions, which are then incorporated into a high resolution two-phase flow solver with fluid-structure interaction (FSI). The large-scale wind-wave interaction model is based on a two-fluid dynamically-coupled approach that employs a high-order spectral method for simulating the water motion and a viscous solver with undulatory boundaries for the air motion. The two-phase flow FSI solver is based on the level set method and is capable of simulating the coupled dynamic interaction of arbitrarily complex bodies with airflow and waves. The large-scale wave field solver is coupled with the near-field FSI solver with a one-way coupling approach by feeding into the latter waves via a pressure-forcing method combined with the level set method. We validate the model for both simple wave trains and three-dimensional directional waves and compare the results with experimental and theoretical solutions. Finally, we demonstrate the capabilities of the new computational framework by carrying out large-eddy simulation of a floating offshore wind turbine interacting with realistic ocean wind and waves.

  15. The Effect of Aerosol-Cloud-Vegetation Interactions and Intraseasonal Meteorological Variability on Warm Cloud Development during the Amazonian Biomass Burning Season

    Science.gov (United States)

    Ten Hoeve, J. E.; Remer, L. A.; Jacobson, M. Z.

    2009-12-01

    The effect of aerosols on the hydrological cycle remains one of the largest uncertainties in our climate system. Biomass burning, from both deforestation and annual agricultural burning, is the largest anthropogenic source of these aerosols in the Southern Hemisphere. Biomass burning aerosols have competing effects on clouds: Depending on the level of aerosol loading and the background cloud characteristics, biomass burning aerosols have been shown in observational studies to invigorate or inhibit cloud formation and/or growth through microphysical and absorptive pathways, respectively. Many of these previous studies have employed all days during the Amazonian burning season months of August through October to formulate aerosol-cloud correlations, assuming relatively constant meteorological conditions exist throughout these months. This study investigates how intraseasonal trends of precipitable water vapor and aerosol loading between August and October impact these aerosol-cloud correlations. Other factors affecting aerosol-cloud relationships, such as atmospheric stability, are also investigated. This study is focused on a small 3 degree NE x 4 degree WE region in Rondonia, Brazil that encompasses extensive, contiguous areas of both forested and deforested land. High resolution aerosol, cloud, water vapor, and atmospheric profile data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites, as well as aerosol and water vapor data from the Aerosol Robotic Network (AERONET), are used collectively to explore the effect of aerosols on water vapor loading and warm cloud development over the Amazon. The difference in aerosol effects on the local hydrological cycle over forested and deforested areas is also examined. This final exercise provides insight into the relationship between aerosols, land-atmosphere processes, and warm clouds.

  16. Polar summer mesospheric extreme horizontal drift speeds during interplanetary corotating interaction regions (CIRs) and high-speed solar wind streams: Coupling between the solar wind and the mesosphere

    Science.gov (United States)

    Lee, Young-Sook; Kirkwood, Sheila; Kwak, Young-Sil; Kim, Kyung-Chan; Shepherd, Gordon G.

    2014-05-01

    We report the observation of echo extreme horizontal drift speed (EEHS, ≥ 300 m s-1) during polar mesospheric (80-90 km) summer echoes (PMSEs) by the VHF (52 MHz) radar at Esrange, Sweden, in years of 2006 and 2008. The EEHS occur in PMSEs as correlated with high-speed solar wind streams (HSSs), observed at least once in 12-17% of all hours of observation for the two summers. The EEHS rate peaks occur either during high solar wind speed in the early part of the PMSE season or during the arrival of interplanetary corotating interaction regions (CIRs) followed by peaks in PMSE occurrence rate after 1-4 days, in the latter part of the 2006 summer. The cause of EEHS rate peaks is likely under the competition between the interval of the CIR and HSS passage over the magnetosphere. A candidate process in producing EEHS is suggested to be localized strong electric field, which is caused by solar wind energy transfer from the interaction of CIR and HSS with the magnetosphere in a sequential manner. We suggest that EEHS are created by strong electric field, estimated as > 10-30 V m-1 at 85 km altitude, exceeding the mesospheric breakdown threshold field.

  17. Pulsar Wind Nebulae with Bow Shocks: Non-thermal Radiation and Cosmic Ray Leptons

    Science.gov (United States)

    Bykov, A. M.; Amato, E.; Petrov, A. E.; Krassilchtchikov, A. M.; Levenfish, K. P.

    2017-07-01

    Pulsars with high spin-down power produce relativistic winds radiating a non-negligible fraction of this power over the whole electromagnetic range from radio to gamma-rays in the pulsar wind nebulae (PWNe). The rest of the power is dissipated in the interactions of the PWNe with the ambient interstellar medium (ISM). Some of the PWNe are moving relative to the ambient ISM with supersonic speeds producing bow shocks. In this case, the ultrarelativistic particles accelerated at the termination surface of the pulsar wind may undergo reacceleration in the converging flow system formed by the plasma outflowing from the wind termination shock and the plasma inflowing from the bow shock. The presence of magnetic perturbations in the flow, produced by instabilities induced by the accelerated particles themselves, is essential for the process to work. A generic outcome of this type of reacceleration is the creation of particle distributions with very hard spectra, such as are indeed required to explain the observed spectra of synchrotron radiation with photon indices Γ≲ 1.5. The presence of this hard spectral component is specific to PWNe with bow shocks (BSPWNe). The accelerated particles, mainly electrons and positrons, may end up containing a substantial fraction of the shock ram pressure. In addition, for typical ISM and pulsar parameters, the e+ released by these systems in the Galaxy are numerous enough to contribute a substantial fraction of the positrons detected as cosmic ray (CR) particles above few tens of GeV and up to several hundred GeV. The escape of ultrarelativistic particles from a BSPWN—and hence, its appearance in the far-UV and X-ray bands—is determined by the relative directions of the interstellar magnetic field, the velocity of the astrosphere and the pulsar rotation axis. In this respect we review the observed appearance and multiwavelength spectra of three different types of BSPWNe: PSR J0437-4715, the Guitar and Lighthouse nebulae, and

  18. Aerodynamic wind-turbine rotor design using surrogate modeling and three-dimensional viscous-inviscid interaction technique

    DEFF Research Database (Denmark)

    Sessarego, Matias; Ramos García, Néstor; Yang, Hua

    2016-01-01

    In this paper a surrogate optimization methodology using a three-dimensional viscous-inviscid interaction code for the aerodynamic design of wind-turbine rotors is presented. The framework presents aunique approach because it does not require the commonly-used blade element momentum (BEM)method. ......In this paper a surrogate optimization methodology using a three-dimensional viscous-inviscid interaction code for the aerodynamic design of wind-turbine rotors is presented. The framework presents aunique approach because it does not require the commonly-used blade element momentum (BEM...... performance can be achieved using the new design method and that themethodology is effective for the aerodynamic design of wind-turbine rotors....

  19. Nonlinear interaction of proton whistler with kinetic Alfvén wave to study solar wind turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, R.; Sharma, R. P. [Centre for Energy Studies, Indian Institute of Technology, Delhi-110016 (India); Goldstein, M. L. [NASA Goddard Space Flight Centre, Code 673, Greenbelt, Maryland 20771 (United States); Dwivedi, N. K. [Austrian Academy of Sciences, Space Research Institute, Schmiedlstrasse 6, 8042 Graz (Austria)

    2013-12-15

    This paper presents the nonlinear interaction between small but finite amplitude kinetic Alfvén wave (KAW) and proton whistler wave using two-fluid model in intermediate beta plasma, applicable to solar wind. The nonlinearity is introduced by modification in the background density. This change in density is attributed to the nonlinear ponderomotive force due to KAW. The solutions of the model equations, governing the nonlinear interaction (and its effect on the formation of localized structures), have been obtained using semi-analytical method in solar wind at 1AU. It is concluded that the KAW properties significantly affect the threshold field required for the filament formation and their critical size (for proton whistler). The magnetic and electric field power spectra have been obtained and their relevance with the recent observations of solar wind turbulence by Cluster spacecraft has been pointed out.

  20. 24-71 GHz PCB Array for 5G ISM

    Science.gov (United States)

    Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

    2017-01-01

    Millimeter-wave 5G mobile architectures need to consolidate disparate frequency bands into a single, multifunctional array. Existing arrays are either narrow-band, prohibitively expensive or cannot be scaled to these frequencies. In this paper, we present the first ultra-wideband millimeter wave array to operate across six 5G and ISM bands spanning 24-71 GHz. Importantly, the array is realized using low-cost PCB. The paper presents the design and optimized layout, and discusses fabrication and measurements.

  1. Aerosol-Cloud Interactions in the South-East Atlantic: Knowledge Gaps, Planned Observations to Address Them, and Implications for Global Climate Change Modeling

    Science.gov (United States)

    Redemann, Jens; Wood, R.; Zuidema, P.; Haywood, J.; Luna, B.; Abel, S.

    2015-01-01

    Southern Africa produces almost a third of the Earth's biomass burning (BB) aerosol particles, yet the fate of these particles and their influence on regional and global climate is poorly understood. Particles lofted into the mid-troposphere are transported westward over the South-East (SE) Atlantic, home to one of the three permanent subtropical Stratocumulus (Sc) cloud decks in the world. The stratocumulus "climate radiators" are critical to the regional and global climate system. They interact with dense layers of BB aerosols that initially overlay the cloud deck, but later subside and are mixed into the clouds. These interactions include adjustments to aerosol-induced solar heating and microphysical effects. As emphasized in the latest IPCC report, the global representation of these aerosol-cloud interaction processes in climate models is one of the largest uncertainty in estimates of future climate. Hence, new observations over the SE Atlantic have significant implications for global climate change scenarios. We discuss the current knowledge of aerosol and cloud property distributions based on satellite observations and sparse suborbital sampling, and describe planned field campaigns in the region. Specifically, we describe the scientific objectives and implementation of the following four synergistic, international research activities aimed at providing a process-level understanding of aerosol-cloud interactions over the SE Atlantic: 1) ORACLES (Observations of Aerosols above Clouds and their interactions), a five-year investigation between 2015 and 2019 with three Intensive Observation Periods (IOP), recently funded by the NASA Earth-Venture Suborbital Program, 2) CLARIFY-2016 (Cloud-Aerosol-Radiation Interactions and Forcing: Year 2016), a comprehensive observational and modeling programme funded by the UK's Natural Environment Research Council (NERC), and supported by the UK Met Office. 3) LASIC (Layered Atlantic Smoke Interactions with Clouds), a funded

  2. Solar wind interaction with small bodies. 2: What can Galileo's detection of magnetic rotations tell us about Gaspra and Ida

    Science.gov (United States)

    Kivelson, M. G.; Wang, Z.; Joy, S.; Khurana, K. K.; Polanskey, C.; Southwood, D. J.; Walker, R. J.

    1995-01-01

    As the Galileo spacecraft passed the asteroids Gaspra in 1990 and Ida in 1993, the magnetometer recorded changes in the solar wind magnetic field that we associate with the presence of the nearby body. This paper focuses on the types of interactions that can produce perturbations in the solar wind. We have suggested that the interaction at Gaspra is consistent with expectations of flow diversion by a magnetic dipole moment and an associated 'magnetosphere' whose scale size is much larger than the diameter of the solid body. The conditions for the Ida flyby leave more room for ambiguity. The observations could plausibly be related to either interaction with a magnetized body or with a conducting body. We will report on details of the observations that may enable us to distinguish between the different types of interaction and to provide quantitative estimates of the physical properties of the asteroids themselves.

  3. Interaction of additive noise and nonlinear dynamics in the double-gyre wind-driven ocean circulation

    NARCIS (Netherlands)

    Sapsis, T.; Dijkstra, H.A.|info:eu-repo/dai/nl/073504467

    2013-01-01

    In this paper the authors study the interactions of additive noise and nonlinear dynamics in a quasi-geostrophicmodel of the double-gyre wind-driven ocean circulation. The recently developed framework of dynamically orthogonal field theory is used to determine the statistics of the flows that arise

  4. DYNAMO: a Mars upper atmosphere package for investigating solar wind interaction and escape processes, and mapping Martian fields

    DEFF Research Database (Denmark)

    Chassefiere, E.; Nagy, A.; Mandea, M.

    2004-01-01

    of periapsis 170 km), and in a lesser extent 2a, offers an unprecedented opportunity to investigate by in situ probing the chemical and dynamical properties of the deep ionosphere, thermosphere, and the interaction between the atmosphere and the solar wind, and therefore the present atmospheric escape rate...

  5. Unveiling aerosol-cloud interactions - Part 2: Minimising the effects of aerosol swelling and wet scavenging in ECHAM6-HAM2 for comparison to satellite data

    Science.gov (United States)

    Neubauer, David; Christensen, Matthew W.; Poulsen, Caroline A.; Lohmann, Ulrike

    2017-11-01

    Aerosol-cloud interactions (ACIs) are uncertain and the estimates of the ACI effective radiative forcing (ERFaci) magnitude show a large variability. Within the Aerosol_cci project the susceptibility of cloud properties to changes in aerosol properties is derived from the high-resolution AATSR (Advanced Along-Track Scanning Radiometer) data set using the Cloud-Aerosol Pairing Algorithm (CAPA) (as described in our companion paper) and compared to susceptibilities from the global aerosol climate model ECHAM6-HAM2 and MODIS-CERES (Moderate Resolution Imaging Spectroradiometer - Clouds and the Earth's Radiant Energy System) data. For ECHAM6-HAM2 the dry aerosol is analysed to mimic the effect of CAPA. Furthermore the analysis is done for different environmental regimes. The aerosol-liquid water path relationship in ECHAM6-HAM2 is systematically stronger than in AATSR-CAPA data and cannot be explained by an overestimation of autoconversion when using diagnostic precipitation but rather by aerosol swelling in regions where humidity is high and clouds are present. When aerosol water is removed from the analysis in ECHAM6-HAM2 the strength of the susceptibilities of liquid water path, cloud droplet number concentration and cloud albedo as well as ERFaci agree much better with those of AATSR-CAPA or MODIS-CERES. When comparing satellite-derived to model-derived susceptibilities, this study finds it more appropriate to use dry aerosol in the computation of model susceptibilities. We further find that the statistical relationships inferred from different satellite sensors (AATSR-CAPA vs. MODIS-CERES) as well as from ECHAM6-HAM2 are not always of the same sign for the tested environmental conditions. In particular the susceptibility of the liquid water path is negative in non-raining scenes for MODIS-CERES but positive for AATSR-CAPA and ECHAM6-HAM2. Feedback processes like cloud-top entrainment that are missing or not well represented in the model are therefore not well

  6. A Mobile-Cloud based Context-Aware and Interactive Framework for Diabetes Management

    Directory of Open Access Journals (Sweden)

    Asmae Benali

    2016-12-01

    Full Text Available One of the biggest preoccupations of any healthcare provider is trying to eliminate the mistakes during treatment. Using Cloud computing permits to host all information in one place and make it accessible anywhere, anytime, and any channel, especially when it comes to the disease diabetes mellitus. Diabetes mellitus is a group of diseases characterized by an elevated blood glucose level (hyperglycemia resulting from defects in insulin secretion, in insulin action, or both. It is, today, the most challenging syndrome in the world. In the latest survey, the world’s 65% of the population is suffering from either Type 1 or Type 2 diabetes mellitus. The patient’s blood glucose level is not the same 24x7 hours in most of the cases and take medication 24x7 hours is impossible. Cloud Computing is so the best solution to check in the patient’s blood glucose control and try to balance it, especially at remote areas where healthcare services aren't easily available.

  7. Interactive graphics on large datasets drives remote condition monitoring on a cloud

    Science.gov (United States)

    Hickinbotham, Simon; Austin, James; McAvoy, John

    2012-05-01

    We demonstrate a new system for condition monitoring using the cloud. The system combines state of the art pattern search capability with youShare, a platform that allows people to run compute-intensive research in an ordered manner over the internet. Data from sensors distributed across one or more assets at one or more sites are uploaded to the cloud compute resource. The uploading triggers the deployment of a range of pattern search services, and is capable of rapidly detecting novel patterns in the data. The outputs of these processes are archived as a matter of course, but are also sent to a further service which processes the data for remote visualisation on a web browser. The system is built in Java, using GWT and RaphaelGWT for graphics rendering. The design of these systems must satisfy conflicting requirements of data currency and data throughput. We present an evaluation of our system that involves processing data at a range of frequencies and bandwidths that are commensurate with commercial requirements. We show that our system has the potential to satisfy a range of processing requirements with minimal latency, and that the user experience is easily sufficient for rapid interpretation of complex condition monitoring data.

  8. ROSAT Observations of Soft X-ray Emission from the Solar Wind Interaction with the Lunar Exosphere

    Science.gov (United States)

    Collier, Michael

    We analyze the ROSAT PSPC soft X-ray image of the moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges, two wedges (one north and one south) 13-32 degrees off (19 degrees wide) the terminator towards the dark side and one wedge 38 degrees wide centered on the antisolar point. The radial profiles of both the north and the south wedges show substantial limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now along with Mars, Venus, and Earth, the moon represents another solar system body at which solar wind charge exchange has been observed.

  9. Aspects of solar wind interaction with Mars: comparison of fluid and hybrid simulations

    Directory of Open Access Journals (Sweden)

    N. V. Erkaev

    2007-02-01

    Full Text Available Mars has no global intrinsic magnetic field, and consequently the solar wind plasma interacts directly with the planetary ionosphere. The main factors of this interaction are: thermalization of plasma after the bow shock, ion pick-up process, and the magnetic barrier effect, which results in the magnetic field enhancement in the vicinity of the obstacle. Results of ideal magnetohydrodynamic and hybrid simulations are compared in the subsolar magnetosheath region. Good agreement between the models is obtained for the magnetic field and plasma parameters just after the shock front, and also for the magnetic field profiles in the magnetosheath. Both models predict similar positions of the proton stoppage boundary, which is known as the ion composition boundary. This comparison allows one to estimate applicability of magnetohydrodynamics for Mars, and also to check the consistency of the hybrid model with Rankine-Hugoniot conditions at the bow shock. An additional effect existing only in the hybrid model is a diffusive penetration of the magnetic field inside the ionosphere. Collisions between ions and neutrals are analyzed as a possible physical reason for the magnetic diffusion seen in the hybrid simulations.

  10. The effect of wave-particle interactions on the polar winds O(+)

    Science.gov (United States)

    Barakat, A. R.; Barghouthi, I. A.

    1994-01-01

    The escape of the polar wind plasma is an important element in the ionosphere-magnetosphere coupling. Both theory and observations indicate that the wave-particle interactions (WPI) play a significant role in the dynamics of ion outflow along open geomagnetic field lines. A Monte Carlo simulation was developed in order to include the effect of the WPI in addition to the factors that are traditionally included in the 'classical' polar wind (i.e. gravity, electrostatic field, and divergence of geomagnetic field lines). The ion distribution function (f(sub j)), as well as the profiles of its moments (density, drift velocity, temperature, etc.) were found for different levels of WPI, that is, for different values of the normalized diffusion rate in the velocity space (D(tilde) (sub j perpendicular). Although the model included O(=), H(+) and eletrons, we presented only the results related to the O(+) ion. We found that (1) both the density and drift velocity of O(+) increased with the WPI strength, and consequently, the O(+) escape flux was enhanced by a factor of up to 10(exp 5), (2) The O(+) ions could be energized up to a few electron volts; (3) for moderate and high levels of WPI D(tilde) (sub perpendicular) (O(+) greater than (tilde) 1, the distribution function f(O(+)) displayed very pronounced conic features at altitudes around 3 R(sub e). Finally, the interplay between the downward body force, the upward mirror force, and the perpendicular heating resulted in the formation of the 'pressure cooker' effect. This phenomena explained some interesting features of our solution, such as, the peak in the O(=) temperature, and the formation of 'ears' and conics for f(O(+)) around 2.5 R(sub e).

  11. Laboratory Simulations of CME-Solar Wind Interactions Using a Coaxial Gun and Background Plasma

    Science.gov (United States)

    Wallace, B. H.; Zhang, Y.; Fisher, D.; Gilmore, M.

    2016-12-01

    Understanding and predicting solar coronal mass ejections (CMEs) is of critical importance for mitigating their disruptive behavior on ground- and space-based technologies. While predictive models of CME propagation and evolution have relied primarily on sparse in-situ data along with ground and satellite images for validation purposes, emerging laboratory efforts have shown that CME-like events can be created with parameters applicable to the solar regime that may likewise aid in predictive modeling. A modified version of the coaxial plasma gun from the Plasma Bubble Expansion Experiment (PBEX) [A. G. Lynn, Y. Zhang, S. C. Hsu, H. Li, W. Liu, M. Gilmore, and C. Watts, Bull. Amer. Phys. Soc. 52, 53 (2007)] will be used in conjunction with the Helicon-Cathode (HelCat) basic plasma science device in order to observe the magnetic characteristics of CMEs as they propagate through the solar wind. The evolution of these interactions will be analyzed using a multi-tip Langmuir probe array, a 33-position B-dot probe array, and a high speed camera. The results of this investigation will be used alongside the University of Michigan's BATS-R-US 3-D MHD numerical code, which will be used to perform simulations of the coaxial plasma gun experiment. The results of these two approaches will be compared in order to validate the capabilities of the BATS-R-US code as well as to further our understanding of magnetic reconnection and other processes that take place as CMEs propagate through the solar wind. The details of the experimental setup as well as the analytical approach are discussed.

  12. Beyond the Flipped Classroom: A Highly Interactive Cloud-Classroom (HIC) Embedded into Basic Materials Science Courses

    Science.gov (United States)

    Liou, Wei-Kai; Bhagat, Kaushal Kumar; Chang, Chun-Yen

    2016-06-01

    The present study compares the highly interactive cloud-classroom (HIC) system with traditional methods of teaching materials science that utilize crystal structure picture or real crystal structure model, in order to examine its learning effectiveness across three dimensions: knowledge, comprehension and application. The aim of this study was to evaluate the (HIC) system, which incorporates augmented reality, virtual reality and cloud-classroom to teach basic materials science courses. The study followed a pretest-posttest quasi-experimental research design. A total of 92 students (aged 19-20 years), in a second-year undergraduate program, participated in this 18-week-long experiment. The students were divided into an experimental group and a control group. The experimental group (36 males and 10 females) was instructed utilizing the HIC system, while the control group (34 males and 12 females) was led through traditional teaching methods. Pretest, posttest, and delayed posttest scores were evaluated by multivariate analysis of covariance. The results indicated that participants in the experimental group who used the HIC system outperformed the control group, in the both posttest and delayed posttest, across three learning dimensions. Based on these results, the HIC system is recommended to be incorporated in formal materials science learning settings.

  13. Cloud and fog interactions with coastal forests in the California Channel Islands

    Science.gov (United States)

    Still, C. J.; Baguskas, S. A.; Williams, P.; Fischer, D. T.; Carbone, M. S.; Rastogi, B.

    2015-12-01

    Coastal forests in California are frequently covered by clouds or immersed in fog in the rain-free summer. Scientists have long surmised that fog might provide critical water inputs to these forests. However, until recently, there has been little ecophysiological research to support how or why plants should prefer foggy regions; similarly, there is very little work quantifying water delivered to ecosystems by fog drip except for a few notable sites along the California coast. However, without spatial datasets of summer cloudcover and fog inundation, combined with detailed process studies, questions regarding the roles of cloud shading and fog drip in dictating plant distributions and ecosystem physiology cannot be addressed effectively. The overall objective of this project is to better understand how cloudcover and fog influence forest metabolism, growth, and distribution. Across a range of sites in California's Channel Islands National Park we measured a wide variety of ecosystem processes and properties. We then related these to cloudcover and fog immersion maps created using satellite datasets and airport and radiosonde observations. We compiled a spatially continuous dataset of summertime cloudcover frequency of the Southern California bight using satellite imagery from the NOAA geostationary GOES-11 Imager. We also created map of summertime cloudcover frequency of this area using MODIS imagery. To assess the ability of our mapping approach to predict spatial and temporal fog inundation patterns, we compared our monthly average daytime fog maps for GOES pixels corresponding to stations where fog inputs were measured with fog collectors in a Bishop pine forest. We also compared our cloudcover maps to measurements of irradiance measurements. Our results demonstrate that cloudcover and fog strongly modulate radiation, water, and carbon budgets, as well as forest distributions, in this semi-arid environment. Measurements of summertime fog drip, pine sapflow and

  14. Making room for interactivity: using the cloud-based audience response system Nearpod to enhance engagement in lectures.

    Science.gov (United States)

    McClean, Stephen; Crowe, William

    2017-03-01

    Active and collaborative learning provides distinct advantages for students in higher education, yet can often be hampered by the barrier of large class sizes. Solutions that combine a 'bring your own device culture' with cloud-based technologies may facilitate a more interactive learning experience. In this pilot study, we describe the use of one such technology, Nearpod, to enhance interactivity in lectures delivered to pharmacy and bioscience students at Ulster University. Existing material in PowerPoint or Keynote format is uploaded to the instructor area of Nearpod, interactive elements are added, and the lecture is then broadcasted via the internet to student devices. The lecturer may choose to share polling responses or examples of submissions from the drawing tool or open-ended questions, thereby providing instant feedback on learning. Students commented favourably on the interactivity and engagement afforded by Nearpod. Most students were happy to use their own electronic devices (smartphones, tablets and laptops) for such activities with a minority expressing concern over problems with connecting to the institutional Wi-Fi. Nearpod and similar products represent a new class of feature-rich audience response systems that have potential to transform learning even in large classes. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Radiatively driven stratosphere-troposphere interactions near the tops of tropical cloud clusters

    Science.gov (United States)

    Churchill, Dean D.; Houze, Robert A., Jr.

    1990-01-01

    Results are presented of two numerical simulations of the mechanism involved in the dehydration of air, using the model of Churchill (1988) and Churchill and Houze (1990) which combines the water and ice physics parameterizations and IR and solar-radiation parameterization with a convective adjustment scheme in a kinematic nondynamic framework. One simulation, a cirrus cloud simulation, was to test the Danielsen (1982) hypothesis of a dehydration mechanism for the stratosphere; the other was to simulate the mesoscale updraft in order to test an alternative mechanism for 'freeze-drying' the air. The results show that the physical processes simulated in the mesoscale updraft differ from those in the thin-cirrus simulation. While in the thin-cirrus case, eddy fluxes occur in response to IR radiative destabilization, and, hence, no net transfer occurs between troposphere and stratosphere, the mesosphere updraft case has net upward mass transport into the lower stratosphere.

  16. Observations of Aerosol-Radiation-Cloud Interactions in the South-East Atlantic: First Results from the ORACLES Deployments in 2016 and 2017

    Science.gov (United States)

    Redemann, Jens; Wood, R.; Zuidema, P.; Diner, D.; Van Harten, G.; Xu, F.; Cairns, B.; Knobelspiesse, K.; Segal Rozenhaimer, M.

    2017-01-01

    Southern Africa produces almost a third of the Earths biomass burning (BB) aerosol particles. Particles lofted into the mid-troposphere are transported westward over the South-East (SE) Atlantic, home to one of the three permanent subtropical stratocumulus (Sc) cloud decks in the world. The SE Atlantic stratocumulus deck interacts with the dense layers of BB aerosols that initially overlay the cloud deck, but later subside and often mix into the clouds. These interactions include adjustments to aerosol-induced solar heating and microphysical effects, and their global representation in climate models remains one of the largest uncertainties in estimates of future climate. Hence, new observations over the SE Atlantic have significant implications for regional and global climate change predictions.The low-level clouds in the SE Atlantic have limited vertical extent and therefore present favorable conditions for their exploration with remote sensing. On the other hand, the normal coexistence of BB aerosols and Sc clouds in the same scene also presents significant challenges to conventional remote sensing techniques. We describe first results from NASAs airborne ORACLES (ObseRvations of Aerosols Above Clouds and Their IntEractionS) deployments in September 2016 and August 2017. We emphasize the unique role of polarimetric observations by two instruments, the Research Scanning Polarimeter (RSP) and the Airborne Multi-angle SpectroPolarimeter Imager (AirMSPI), and describe how these instruments help address specific ORACLES science objectives. Initial assessments of polarimetric observation accuracy for key cloud and aerosol properties will be presented, in as far as the preliminary nature of measurements permits.

  17. A new approach to modeling aerosol effects on East Asian climate: Parametric uncertainties associated with emissions, cloud microphysics, and their interactions: AEROSOL EFFECTS ON EAST ASIAN CLIMATE

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Huiping [College of Atmospheric Sciences, Lanzhou University, Lanzhou China; Pacific Northwest National Laboratory, Richland Washington USA; Qian, Yun [Pacific Northwest National Laboratory, Richland Washington USA; Zhao, Chun [Pacific Northwest National Laboratory, Richland Washington USA; Wang, Hailong [Pacific Northwest National Laboratory, Richland Washington USA; Wang, Minghuai [Institute for Climate and Global Change Research and School of Atmospheric Science, Nanjing University, Nanjing China; Jiangsu Collaborative Innovation Center for Climate Change, Nanjing China; Yang, Ben [Pacific Northwest National Laboratory, Richland Washington USA; Institute for Climate and Global Change Research and School of Atmospheric Science, Nanjing University, Nanjing China; Liu, Xiaohong [Department of Atmospheric Science, University of Wyoming, Laramie Wyoming USA; Fu, Qiang [College of Atmospheric Sciences, Lanzhou University, Lanzhou China; Department of Atmospheric Sciences, University of Washington, Seattle Washington USA

    2015-09-09

    In this study, we adopt a parametric sensitivity analysis framework that integrates the quasi-Monte Carlo parameter sampling approach and a surrogate model to examine aerosol effects on the East Asian Monsoon climate simulated in the Community Atmosphere Model (CAM5). A total number of 256 CAM5 simulations are conducted to quantify the model responses to the uncertain parameters associated with cloud microphysics parameterizations and aerosol (e.g., sulfate, black carbon (BC), and dust) emission factors and their interactions. Results show that the interaction terms among parameters are important for quantifying the sensitivity of fields of interest, especially precipitation, to the parameters. The relative importance of cloud-microphysics parameters and emission factors (strength) depends on evaluation metrics or the model fields we focused on, and the presence of uncertainty in cloud microphysics imposes an additional challenge in quantifying the impact of aerosols on cloud and climate. Due to their different optical and microphysical properties and spatial distributions, sulfate, BC, and dust aerosols have very different impacts on East Asian Monsoon through aerosol-cloud-radiation interactions. The climatic effects of aerosol do not always have a monotonic response to the change of emission factors. The spatial patterns of both sign and magnitude of aerosol-induced changes in radiative fluxes, cloud, and precipitation could be different, depending on the aerosol types, when parameters are sampled in different ranges of values. We also identify the different cloud microphysical parameters that show the most significant impact on climatic effect induced by sulfate, BC and dust, respectively, in East Asia.

  18. Unveiling aerosol–cloud interactions – Part 2: Minimising the effects of aerosol swelling and wet scavenging in ECHAM6-HAM2 for comparison to satellite data

    Directory of Open Access Journals (Sweden)

    D. Neubauer

    2017-11-01

    Full Text Available Aerosol–cloud interactions (ACIs are uncertain and the estimates of the ACI effective radiative forcing (ERFaci magnitude show a large variability. Within the Aerosol_cci project the susceptibility of cloud properties to changes in aerosol properties is derived from the high-resolution AATSR (Advanced Along-Track Scanning Radiometer data set using the Cloud–Aerosol Pairing Algorithm (CAPA (as described in our companion paper and compared to susceptibilities from the global aerosol climate model ECHAM6-HAM2 and MODIS–CERES (Moderate Resolution Imaging Spectroradiometer – Clouds and the Earth's Radiant Energy System data. For ECHAM6-HAM2 the dry aerosol is analysed to mimic the effect of CAPA. Furthermore the analysis is done for different environmental regimes. The aerosol–liquid water path relationship in ECHAM6-HAM2 is systematically stronger than in AATSR–CAPA data and cannot be explained by an overestimation of autoconversion when using diagnostic precipitation but rather by aerosol swelling in regions where humidity is high and clouds are present. When aerosol water is removed from the analysis in ECHAM6-HAM2 the strength of the susceptibilities of liquid water path, cloud droplet number concentration and cloud albedo as well as ERFaci agree much better with those of AATSR–CAPA or MODIS–CERES. When comparing satellite-derived to model-derived susceptibilities, this study finds it more appropriate to use dry aerosol in the computation of model susceptibilities. We further find that the statistical relationships inferred from different satellite sensors (AATSR–CAPA vs. MODIS–CERES as well as from ECHAM6-HAM2 are not always of the same sign for the tested environmental conditions. In particular the susceptibility of the liquid water path is negative in non-raining scenes for MODIS–CERES but positive for AATSR–CAPA and ECHAM6-HAM2. Feedback processes like cloud-top entrainment that are missing or not well represented

  19. The effect of ISM absorption on stellar activity measurements and its relevance for exoplanet studies

    Science.gov (United States)

    Fossati, L.; Marcelja, S. E.; Staab, D.; Cubillos, P. E.; France, K.; Haswell, C. A.; Ingrassia, S.; Jenkins, J. S.; Koskinen, T.; Lanza, A. F.; Redfield, S.; Youngblood, A.; Pelzmann, G.

    2017-05-01

    Past ultraviolet and optical observations of stars hosting close-in Jupiter-mass planets have shown that some of these stars present an anomalously low chromospheric activity, significantly below the basal level. For the hot Jupiter planet host WASP-13, observations have shown that the apparent lack of activity is possibly caused by absorption from the intervening interstellar medium (ISM). Inspired by this result, we study the effect of ISM absorption on activity measurements (S and log R 'HK indices) for main-sequence late-type stars. To this end, we employ synthetic stellar photospheric spectra combined with varying amounts of chromospheric emission and ISM absorption. We present the effect of ISM absorption on activity measurements by varying several instrumental (spectral resolution), stellar (projected rotational velocity, effective temperature, and chromospheric emission flux), and ISM parameters (relative velocity between stellar and ISM Ca II lines, broadening b-parameter, and Ca II column density). We find that for relative velocities between the stellar and ISM lines smaller than 30-40 km s-1 and for ISM Ca II column densities log NCaII ⪆ 12, the ISM absorption has a significant influence on activity measurements. Direct measurements and three dimensional maps of the Galactic ISM absorption indicate that an ISM Ca II column density of log NCaII = 12 is typically reached by a distance of about 100 pc along most sight lines. In particular, for a Sun-like star lying at a distance greater than 100 pc, we expect a depression (bias) in the log R'HK value larger than 0.05-0.1 dex, about the same size as the typical measurement and calibration uncertainties on this parameter. This work shows that the bias introduced by ISM absorption must always be considered when measuring activity for stars lying beyond 100 pc. We also consider the effect of multiple ISM absorption components. We discuss the relevance of this result for exoplanet studies and revise the

  20. MOLNs: A CLOUD PLATFORM FOR INTERACTIVE, REPRODUCIBLE, AND SCALABLE SPATIAL STOCHASTIC COMPUTATIONAL EXPERIMENTS IN SYSTEMS BIOLOGY USING PyURDME

    Science.gov (United States)

    Drawert, Brian; Trogdon, Michael; Toor, Salman; Petzold, Linda; Hellander, Andreas

    2017-01-01

    Computational experiments using spatial stochastic simulations have led to important new biological insights, but they require specialized tools and a complex software stack, as well as large and scalable compute and data analysis resources due to the large computational cost associated with Monte Carlo computational workflows. The complexity of setting up and managing a large-scale distributed computation environment to support productive and reproducible modeling can be prohibitive for practitioners in systems biology. This results in a barrier to the adoption of spatial stochastic simulation tools, effectively limiting the type of biological questions addressed by quantitative modeling. In this paper, we present PyURDME, a new, user-friendly spatial modeling and simulation package, and MOLNs, a cloud computing appliance for distributed simulation of stochastic reaction-diffusion models. MOLNs is based on IPython and provides an interactive programming platform for development of sharable and reproducible distributed parallel computational experiments. PMID:28190948

  1. Coupled fluid-structure interaction simulation of floating offshore wind turbines and waves: a large eddy simulation approach

    Science.gov (United States)

    Calderer, Antoni; Guo, Xin; Shen, Lian; Sotiropoulos, Fotis

    2014-06-01

    We develop a computational framework for simulating the coupled interaction of complex floating structures with large-scale ocean waves and atmospheric turbulent winds. The near-field approach features a partitioned fluid-structure interaction model (FSI) combining the curvilinear immersed boundary (CURVIB) method of Borazjani and Sotiropoulos (J. Comput. Phys. 2008) and the two-phase flow level set formulation of Kang and Sotiropoulos (Adv. in Water Res. 2012) and is capable of solving complex free-surface flows interacting non-linearly with complex real life floating structures. The near-field solver is coupled with a large-scale wave and wind model based on the two-fluid approach of Yang and Shen (J. Comput. Phys. 2011) which integrates a viscous Navier-Stokes solver with undulatory boundaries for the motion of the air and an efficient potential-flow based wave solver. The large-scale turbulent wind is incorporated from the far-field solver to the near-field solver by feeding into the latter inlet boundary conditions. The wave field is incorporated to the near-field solver by using the pressure-forcing method of Guo and Shen (J. Comput. Phys. 2009) which has been appropriately adapted to the level set method. The algorithm for coupling the two codes has been validated for a variety of wave cases including a broadband spectrum showing excellent agreement when compared to theoretical results. Finally, the capabilities of the numerical framework are demonstrated by carrying out large eddy simulation (LES) of a floating wind turbine interacting with realistic ocean wind and wave conditions.

  2. Analysis of Aircraft, Radiosonde and Radar Observations in Cirrus Clouds Observed During FIRE II: The Interactions Between Environmental Structure, Turbulence and Cloud Microphysical Properties

    Science.gov (United States)

    Smith, Samantha A.; DelGenio, Anthony D.

    1999-01-01

    Ways to determine the turbulence intensity and the horizontal variability in cirrus clouds have been investigated using FIRE-II aircraft, radiosonde and radar data. Higher turbulence intensities were found within some, but not all, of the neutrally stratified layers. It was also demonstrated that the stability of cirrus layers with high extinction values decrease in time, possibly as a result of radiative destabilization. However, these features could not be directly related to each other in any simple manner. A simple linear relationship was observed between the amount of horizontal variability in the ice water content and its average value. This was also true for the extinction and ice crystal number concentrations. A relationship was also suggested between the variability in cloud depth and the environmental stability across the depth of the cloud layer, which requires further investigation.

  3. Analysis of co-located MODIS and CALIPSO observations near clouds

    Directory of Open Access Journals (Sweden)

    T. Várnai

    2012-02-01

    Full Text Available This paper aims at helping synergistic studies in combining data from different satellites for gaining new insights into two critical yet poorly understood aspects of anthropogenic climate change, aerosol-cloud interactions and aerosol radiative effects. In particular, the paper examines the way cloud information from the MODIS (MODerate resolution Imaging Spectroradiometer imager can refine our perceptions based on CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization lidar measurements about the systematic aerosol changes that occur near clouds.

    The statistical analysis of a yearlong dataset of co-located global maritime observations from the Aqua and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellites reveals that MODIS's multispectral imaging ability can greatly help the interpretation of CALIOP observations. The results show that imagers on Aqua and CALIPSO yield very similar pictures, and that the discrepancies – due mainly to wind drift and differences in view angle – do not significantly hinder aerosol measurements near clouds. By detecting clouds outside the CALIOP track, MODIS reveals that clouds are usually closer to clear areas than CALIOP data alone would suggest. The paper finds statistical relationships between the distances to clouds in MODIS and CALIOP data, and proposes a rescaling approach to statistically account for the impact of clouds outside the CALIOP track even when MODIS cannot reliably detect low clouds, for example at night or over sea ice. Finally, the results show that the typical distance to clouds depends on both cloud coverage and cloud type, and accordingly varies with location and season. In maritime areas perceived cloud free, the global median distance to clouds below 3 km altitude is in the 4–5 km range.

  4. Observation of summer daytime aurora in the noctilucent cloud layer and its link to high-energy particle precipitation during high-speed solar wind streams

    Science.gov (United States)

    Lee, Y.; Kwak, Y. S.; Kim, K. C.; Solheim, B.; Park, J.

    2015-12-01

    Aurora produced by precipitating low-energy electrons can be suppressed in summer daytime. However, the high-energy electrons (>30 keV) that are unsuppressed by sunlight are capable of penetrating deep into the mesosphere, where they can produce the odd hydrogen (HOx) and eventually lead to catalytic ozone (O3) loss. By elevating the D-region ionization level, they also play the important role of facilitating the production of polar mesospheric summer echoes (PMSE) as a precursor of polar mesospheric clouds (PMC). In the present study, it was discovered that high-energy electrons induce supersonic luminous phenomena, including the enhancement of O(1S) 557.7-nm emission with an intensity of up to 300 kR (horizontally integrated) and a supersonic velocity (300-1500 m s-1) as seen within a field of view that is 150-km wide, also called a supersonic burst (SB). SB-accompanied O(1S) emission enhancement is differentiated from aurora because the former occurs only in summer daytime, at a low altitude of ~80 km, and in the form of an intense localised burst. The source of the SB energy might be linked to the precipitation of high-energy electrons (>30 keV), especially as observed during high-speed solar wind streams (HSSs). In producing O(1S) emission, the secondary electron number flux of the precipitated primary electrons increases in magnitude by as much as an order of four, and a local process is required to provide the supplement. The supplementary local process may involve a supersonic velocity possibly caused by ion acceleration in a strong electric field, resulting in the inducement of electron acceleration in the field.

  5. Flight and wind-tunnel comparisons of the inlet-airframe interaction of the F-15 airplane

    Science.gov (United States)

    Webb, L. D.; Andriyich-Varda, D.; Whitmore, S. A.

    1984-01-01

    The design of inlets and nozzles and their interactions with the airplane which may account for a large percentage of the total drag of modern high performance aircraft is discussed. The inlet/airframe interactions program and the flight tests conducted is described. Inlet drag and lift data from a 7.5% wind-tunnel model are compared with data from an F-15 airplane with instrumentation to match the model. Pressure coefficient variations with variable cowl angles, capture ratios, examples of flow interactions and angles of attack are for Mach numbers of 0.6, 0.9, 1.2, and 1.5 are presented.

  6. Challenges in Measuring External Currents Driven by the Solar Wind-Magnetosphere Interaction

    Science.gov (United States)

    Le, Guan; Slavin, James A.; Pfaff, Robert F.

    2014-01-01

    In studying the Earth's geomagnetism, it has always been a challenge to separate magnetic fields from external currents originating from the ionosphere and magnetosphere. While the internal magnetic field changes very slowly in time scales of years and more, the ionospheric and magnetospheric current systems driven by the solar wind -magnetosphere interaction are very dynamic. They are intimately controlled by the ionospheric electrodynamics and ionospheremagnetosphere coupling. Single spacecraft observations are not able to separate their spatial and temporal variations, and thus to accurately describe their configurations. To characterize and understand the external currents, satellite observations require both good spatial and temporal resolutions. This paper reviews our observations of the external currents from two recent LEO satellite missions: Space Technology 5 (ST-5), NASA's first three-satellite constellation mission in LEO polar orbit, and Communications/Navigation Outage Forecasting System (C/NOFS), an equatorial satellite developed by US Air Force Research Laboratory. We present recommendations for future geomagnetism missions based on these observations.

  7. Motion and interaction of decaying trailing vortices in spanwise shear wind

    Science.gov (United States)

    Liu, C. H.; Lu, T.

    1986-01-01

    A simulation is presented of the drift of trailing vortices in a cross-wind near the ground by an unsteady, two-dimensional, rotational flow field with a concentration of large vorticity in vortical spots (having a finite but small effective size and finite total strength). The problem is analyzed by a combination of the method of matched asymptotic analyses for the decay of the vortical spots and the Euler solution for the unsteady rotational flow. Using the method of averaging, a special numerical method is developed in which the grid size and time step depend only on the length and velocity scales of the background flow and are independent of the effective core size of a vortical spot. The core size can be much smaller than the grid size, whereas the peak velocity in the core is inversely propertional to the spot size. Numerical results are presented to demonstrate the strong interaction between the trajectories of the vortical spots and the change of the vorticity distribution in the background flow field.

  8. Interaction of energetic particles with waves in strongly inhomogeneous solar wind plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Krafft, C. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau Cedex (France); Volokitin, A. S. [Space Research Institute, 84/32 Profsoyuznaya Str., 117997 Moscow (Russian Federation); Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace, 3A Av. de la Recherche Scientifique, F-45071 Orléans Cedex 2 (France)

    2013-12-01

    Observations performed in the solar wind by different satellites show that electron beams accelerated in the low corona during solar flares can propagate up to distances around 1 AU, that Langmuir waves' packets can be clumped into spikes with peak amplitudes three orders of magnitude above the mean, and that the average level of density fluctuations can reach several percents. A Hamiltonian model is built describing the properties of Langmuir waves propagating in a plasma with random density fluctuations by the Zakharov's equations and the beam by means of particles moving self-consistently in the fields of the waves. Numerical simulations, performed using parameters relevant to solar type III conditions at 1 AU, show that when the average level of density fluctuations is sufficiently low, the beam relaxation and the wave excitation processes are very similar to those in a homogeneous plasma and can be described by the quasilinear equations of the weak turbulence theory. On the contrary, when the average level of density fluctuations overcomes some threshold depending on the ratio of the thermal velocity to the beam velocity, the plasma inhomogeneities crucially influence the characteristics of the Langmuir turbulence and the beam-plasma interaction.

  9. Experimental validation of a Fluid-Structure interaction model for simulating offshore floating wind turbines

    Science.gov (United States)

    Calderer, Antoni; Feist, Christ; Ruehl, Kelley; Guala, Michele; Sotiropoulos, Fotis

    2014-11-01

    A series of experiments reproducing a floating wind turbine in operational sea conditions, conducted in the St. Anthony Falls Lab. wave facility, are employed to validate the capabilities of the recently developed FSI-Levelset-CURVIB method of Calderer, Kang and Sotiropoulos (JCP 2014) to accurately predict turbine-wave interactions. The numerical approach is based on solving the Navier-Stokes equations coupled with the level set method, which is capable of carrying out LES of two-phase flows (air and water) with complex floating structures and waves. The investigated floating turbine is a 1:100 Froude scaled version of the 13.2 MW prototype designed by Sandia National Lab; it is installed on a cylindrical barge style platform which is restricted to move with two degrees of freedom, heave and pitch in the vertical plane defined by the direction of the propagating 2D waves. The computed turbine kinematics as well as the free surface elevation results are compared with the experimental data for different free decay tests and wave conditions representative of the Maine and the Pacific North West coasts. The comparison shows promising results indicating the validity of the model for simulating operational floating turbines. This work is supported by the US Department of Energy (DE-EE0005482), the University of Minnesota IREE program, and the Minnesota Supercomputing Institute.

  10. Numerical simulation of wave-current interaction under strong wind conditions

    Science.gov (United States)

    Larrañaga, Marco; Osuna, Pedro; Ocampo-Torres, Francisco Javier

    2017-04-01

    Although ocean surface waves are known to play an important role in the momentum and other scalar transfer between the atmosphere and the ocean, most operational numerical models do not explicitly include the terms of wave-current interaction. In this work, a numerical analysis about the relative importance of the processes associated with the wave-current interaction under strong off-shore wind conditions in Gulf of Tehuantepec (the southern Mexican Pacific) was carried out. The numerical system includes the spectral wave model WAM and the 3D hydrodynamic model POLCOMS, with the vertical turbulent mixing parametrized by the kappa-epsilon closure model. The coupling methodology is based on the vortex-force formalism. The hydrodynamic model was forced at the open boundaries using the HYCOM database and the wave model was forced at the open boundaries by remote waves from the southern Pacific. The atmospheric forcing for both models was provided by a local implementation of the WRF model, forced at the open boundaries using the CFSR database. The preliminary analysis of the model results indicates an effect of currents on the propagation of the swell throughout the study area. The Stokes-Coriolis term have an impact on the transient Ekman transport by modifying the Ekman spiral, while the Stokes drift has an effect on the momentum advection and the production of TKE, where the later induces a deepening of the mixing layer. This study is carried out in the framework of the project CONACYT CB-2015-01 255377 and RugDiSMar Project (CONACYT 155793).

  11. Arctic PBL Cloud Height and Motion Retrievals from MISR and MINX

    Science.gov (United States)

    Wu, Dong L.

    2012-01-01

    How Arctic clouds respond and feedback to sea ice loss is key to understanding of the rapid climate change seen in the polar region. As more open water becomes available in the Arctic Ocean, cold air outbreaks (aka. off-ice flow from polar lows) produce a vast sheet of roll clouds in the planetary boundary layer (PBl). The cold air temperature and wind velocity are the critical parameters to determine and understand the PBl structure formed under these roll clouds. It has been challenging for nadir visible/IR sensors to detect Arctic clouds due to lack of contrast between clouds and snowy/icy surfaces. In addition) PBl temperature inversion creates a further problem for IR sensors to relate cloud top temperature to cloud top height. Here we explore a new method with the Multiangle Imaging Spectro-Radiometer (MISR) instrument to measure cloud height and motion over the Arctic Ocean. Employing a stereoscopic-technique, MISR is able to measure cloud top height accurately and distinguish between clouds and snowy/icy surfaces with the measured height. We will use the MISR INteractive eXplorer (MINX) to quantify roll cloud dynamics during cold-air outbreak events and characterize PBl structures over water and over sea ice.

  12. Marking the Passage of Time (2003-2013): Reflections on ISME at Its 60th Anniversary

    Science.gov (United States)

    McCarthy, Marie

    2017-01-01

    The International Society for Music Education (ISME) celebrated its 60th anniversary on July 7, 2013. This article documents a history of the Society in its sixth decade (2003-2013). Two interrelated perspectives, consolidation and expansion, are used to synthesize patterns of development. Various partnerships created and sustained by ISME enabled…

  13. ISMS: A New Model for Improving Student Motivation and Self-Esteem in Primary Education

    Science.gov (United States)

    Ghilay, Yaron; Ghilay, Ruth

    2015-01-01

    In this study we introduce a new model for primary education called ISMS: Improving Student Motivation and Self-esteem. Following a two-year study undertaken in a primary school (n = 67), the new model was found to be successful. Students who participated in the research, reported that a course based on ISMS principles was very helpful for…

  14. Õismäe uusarendus tekitab elanikes küsimusi / Kadri Penjam

    Index Scriptorium Estoniae

    Penjam, Kadri, 1980-

    2008-01-01

    Kinnisvaraarendajatel on plaan ehitada Õismäele Harku järve poolsesse külge uued korterelamud, parlamendiliikme Taavi Rõivase hinnangul väärib aga Õismäe miljöö hoidmist ning elanike seisukohtadega tuleb arvestada. Lisa: Detailplaneeringu eskiis

  15. Large Scale Monte Carlo Simulation of Neutrino Interactions Using the Open Science Grid and Commercial Clouds

    Science.gov (United States)

    Norman, A.; Boyd, J.; Davies, G.; Flumerfelt, E.; Herner, K.; Mayer, N.; Mhashilhar, P.; Tamsett, M.; Timm, S.

    2015-12-01

    Modern long baseline neutrino experiments like the NOvA experiment at Fermilab, require large scale, compute intensive simulations of their neutrino beam fluxes and backgrounds induced by cosmic rays. The amount of simulation required to keep the systematic uncertainties in the simulation from dominating the final physics results is often 10x to 100x that of the actual detector exposure. For the first physics results from NOvA this has meant the simulation of more than 2 billion cosmic ray events in the far detector and more than 200 million NuMI beam spill simulations. Performing these high statistics levels of simulation have been made possible for NOvA through the use of the Open Science Grid and through large scale runs on commercial clouds like Amazon EC2. We details the challenges in performing large scale simulation in these environments and how the computing infrastructure for the NOvA experiment has been adapted to seamlessly support the running of different simulation and data processing tasks on these resources.

  16. General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) – integrating aerosol research from nano to global scales

    DEFF Research Database (Denmark)

    Kulmala, M.; Asmi, A.; Lappalainen, H. K.

    2011-01-01

    In this paper we describe and summarize the main achievements of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy including: (a) a comprehensive database with a year of observat...

  17. General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI)-integrating aerosol research from nano to global scales

    NARCIS (Netherlands)

    Kulmala, M.; Asmi, A.; Lappalainen, H.K.; Baltensperger, U.; Brenguier, J.-L.; Facchini, M.C.; Hansson, H.-C.; Hov, Ø.; O'Dowd, C.D.; Pöschl, U.; Wiedensohler, A.; Boers, R.; Boucher, O.; Leeuw, G. de; Denier van der Gon, H.A.C.; Feichter, J.; Krejci, R.; Laj, P.; Lihavainen, H.; Lohmann, U.; McFiggans, G.; Mentel, T.; Pilinis, C.; Riipinen, I.; Schulz, M.; Stohl, A.; Swietlicki, E.; Vignati, E.; Alves, C.; Amann, M.; Ammann, M.; Arabas, S.; Artaxo, P.; Baars, H.; Beddows, D.C.S.; Bergström, R.; Beukes, J.P.; Bilde, M.; Burkhart, J.F.; Canonaco, F.; Clegg, S.L.; Coe, H.; Crumeyrolle, S.; D'Anna, B.; Decesari, S.; Gilardoni, S.; Fischer, M.; Fjaeraa, A.M.; Fountoukis, C.; George, C.; Gomes, L.; Halloran, P.; Hamburger, T.; Harrison, R.M.; Herrmann, H.; Hoffmann, T.; Hoose, C.; Hu, M.; Hyvärinen, A.; Hõrrak, U.; Iinuma, Y.; Iversen, T.; Josipovic, M.; Kanakidou, M.; Kiendler-Scharr, A.; Kirkevåg, A.; Kiss, G.; Klimont, Z.; Kolmonen, P.; Komppula, M.; Kristjánsson, J.-E.; Laakso, L.; Laaksonen, A.; Labonnote, L.; Lanz, V.A.; Lehtinen, K.E.J.; Rizzo, L.V.; Makkonen, R.; Manninen, H.E.; McMeeking, G.; Merikanto, J.; Minikin, A.; Mirme, S.; Morgan, W.T.; Nemitz, E.; O'Donnell, D.; Panwar, T.S.; Pawlowska, H.; Petzold, A.; Pienaar, J.J.; Pio, C.; Plass-Duelmer, C.; Prévôt, A.S.H.; Pryor, S.; Reddington, C.L.; Roberts, G.; Rosenfeld, D.; Schwarz, J.; Seland, O.; Sellegri, K.; Shen, X.J.; Shiraiwa, M.; Siebert, H.; Sierau, B.; Simpson, D.; Sun, J.Y.; Topping, D.; Tunved, P.; Vaattovaara, P.; Vakkari, V.; Veefkind, J.P.; Visschedijk, A.; Vuollekoski, H.; Vuolo, R.; Wehner, B.; Wildt, J.; Woodward, S.; Worsnop, D.R.; Zadelhoff, G.J. van; Zardini, A.A.; Zhang, K.; Zyl, P.G. van; Kerminen, V.-M.; Carslaw, K.S.; Pandis, S.N.

    2011-01-01

    In this paper we describe and summarize the main achievements of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy including: (a) a comprehensive database with a year of

  18. ScipionCloud: An integrative and interactive gateway for large scale cryo electron microscopy image processing on commercial and academic clouds.

    Science.gov (United States)

    Cuenca-Alba, Jesús; Del Cano, Laura; Gómez Blanco, Josué; de la Rosa Trevín, José Miguel; Conesa Mingo, Pablo; Marabini, Roberto; S Sorzano, Carlos Oscar; Carazo, Jose María

    2017-10-01

    New instrumentation for cryo electron microscopy (cryoEM) has significantly increased data collection rate as well as data quality, creating bottlenecks at the image processing level. Current image processing model of moving the acquired images from the data source (electron microscope) to desktops or local clusters for processing is encountering many practical limitations. However, computing may also take place in distributed and decentralized environments. In this way, cloud is a new form of accessing computing and storage resources on demand. Here, we evaluate on how this new computational paradigm can be effectively used by extending our current integrative framework for image processing, creating ScipionCloud. This new development has resulted in a full installation of Scipion both in public and private clouds, accessible as public "images", with all the required preinstalled cryoEM software, just requiring a Web browser to access all Graphical User Interfaces. We have profiled the performance of different configurations on Amazon Web Services and the European Federated Cloud, always on architectures incorporating GPU's, and compared them with a local facility. We have also analyzed the economical convenience of different scenarios, so cryoEM scientists have a clearer picture of the setup that is best suited for their needs and budgets. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Real-time 3-D hybrid simulation of Titan's plasma interaction during a solar wind excursion

    Directory of Open Access Journals (Sweden)

    S. Simon

    2009-09-01

    Full Text Available The plasma environment of Saturn's largest satellite Titan is known to be highly variable. Since Titan's orbit is located within the outer magnetosphere of Saturn, the moon can leave the region dominated by the magnetic field of its parent body in times of high solar wind dynamic pressure and interact with the thermalized magnetosheath plasma or even with the unshocked solar wind. By applying a three-dimensional hybrid simulation code (kinetic description of ions, fluid electrons, we study in real-time the transition that Titan's plasma environment undergoes when the moon leaves Saturn's magnetosphere and enters the supermagnetosonic solar wind. In the simulation, the transition between both plasma regimes is mimicked by a reversal of the magnetic field direction as well as a change in the composition and temperature of the impinging plasma flow. When the satellite enters the solar wind, the magnetic draping pattern in its vicinity is reconfigured due to reconnection, with the characteristic time scale of this process being determined by the convection of the field lines in the undisturbed plasma flow at the flanks of the interaction region. The build-up of a bow shock ahead of Titan takes place on a typical time scale of a few minutes as well. We also analyze the erosion of the newly formed shock front upstream of Titan that commences when the moon re-enters the submagnetosonic plasma regime of Saturn's magnetosphere. Although the model presented here is far from governing the full complexity of Titan's plasma interaction during a solar wind excursion, the simulation provides important insights into general plasma-physical processes associated with such a disruptive change of the upstream flow conditions.

  20. Particle-in-cell simulations of the solar wind interaction with lunar crustal magnetic anomalies: Magnetic cusp regions

    Science.gov (United States)

    Poppe, A. R.; Halekas, J. S.; Delory, G. T.; Farrell, W. M.

    2012-09-01

    As the solar wind is incident upon the lunar surface, it will occasionally encounter lunar crustal remanent magnetic fields. These magnetic fields are small-scale, highly non-dipolar, have strengths up to hundreds of nanotesla, and typically interact with the solar wind in a kinetic fashion. Simulations, theoretical analyses, and spacecraft observations have shown that crustal fields can reflect solar wind protons via a combination of magnetic and electrostatic reflection; however, analyses of surface properties have suggested that protons may still access the lunar surface in the cusp regions of crustal magnetic fields. In this first report from a planned series of studies, we use a 11/2-dimensional, electrostatic particle-in-cell code to model the self-consistent interaction between the solar wind, the cusp regions of lunar crustal remanent magnetic fields, and the lunar surface. We describe the self-consistent electrostatic environment within crustal cusp regions and discuss the implications of this work for the role that crustal fields may play regulating space weathering of the lunar surface via proton bombardment.

  1. Soft Clouding

    DEFF Research Database (Denmark)

    Søndergaard, Morten; Markussen, Thomas; Wetton, Barnabas

    2012-01-01

    Soft Clouding is a blended concept, which describes the aim of a collaborative and transdisciplinary project. The concept is a metaphor implying a blend of cognitive, embodied interaction and semantic web. Furthermore, it is a metaphor describing our attempt of curating a new semantics of sound...... brought together in one transdisciplinary process of curating a semantics of sound: Technological, Humanistic /Curatorial, and Design / Action-based practice....

  2. Soft Clouding

    DEFF Research Database (Denmark)

    Søndergaard, Morten; Markussen, Thomas; Wetton, Barnabas

    2012-01-01

    Soft Clouding is a blended concept, which describes the aim of a collaborative and transdisciplinary project. The concept is a metaphor implying a blend of cognitive, embodied interaction and semantic web. Furthermore, it is a metaphor describing our attempt of curating a new semantics of sound a...... brought together in one transdisciplinary process of curating a semantics of sound: Technological, Humanistic /Curatorial, and Design / Action-based practice....

  3. Wind tunnel study of the wind turbine interaction with a boundary-layer flow: Upwind region, turbine performance, and wake region

    Science.gov (United States)

    Bastankhah, M.; Porté-Agel, F.

    2017-06-01

    Comprehensive wind tunnel experiments were carried out to study the interaction of a turbulent boundary layer with a wind turbine operating under different tip-speed ratios and yaw angles. Force and power measurements were performed to characterize the variation of thrust force (both magnitude and direction) and generated power of the wind turbine under different operating conditions. Moreover, flow measurements, collected using high-resolution particle-image velocimetry as well as hot-wire anemometry, were employed to systematically study the flow in the upwind, near-wake, and far-wake regions. These measurements provide new insights into the effect of turbine operating conditions on flow characteristics in these regions. For the upwind region, the results show a strong lateral asymmetry under yawed conditions. For the near-wake region, the evolution of tip and root vortices was studied with the use of both instantaneous and phase-averaged vorticity fields. The results suggest that the vortex breakdown position cannot be determined based on phase-averaged statistics, particularly for tip vortices under turbulent inflow conditions. Moreover, the measurements in the near-wake region indicate a complex velocity distribution with a speed-up region in the wake center, especially for higher tip-speed ratios. In order to elucidate the meandering tendency of far wakes, particular focus was placed on studying the characteristics of large turbulent structures in the boundary layer and their interaction with wind turbines. Although these structures are elongated in the streamwise direction, their cross sections are found to have a size comparable to the rotor area, so that they can be affected by the presence of the turbine. In addition, the study of spatial coherence in turbine wakes reveals that any statistics based on streamwise velocity fluctuations cannot provide reliable information about the size of large turbulent structures in turbine wakes due to the effect of wake

  4. Effects of soil–structure interaction on real time dynamic response of offshore wind turbines on monopiles

    DEFF Research Database (Denmark)

    Damgaard, M.; Zania, Varvara; Andersen, L.V.

    2014-01-01

    , a computationally efficient modelling approach of including the dynamic soil–structure interaction into aeroelastic codes is presented with focus on monopile foundations. Semi-analytical frequency-domain solutions are applied to evaluate the dynamic impedance functions of the soil–pile system at a number...... normal operating mode. The aeroelastic response is evaluated for three different foundation conditions, i.e. apparent fixity length, the consistent lumped-parameter model and fixed support at the seabed. The effect of soil–structure interaction is shown to be critical for the design, estimated in terms......Offshore wind turbines are highly dynamically loaded structures, their response being dominated by the interrelation effects between the turbine and the support structure. Since the dynamic response of wind turbine structures occurs in a frequency range close to the excitation frequencies related...

  5. Solar variability and clouds

    CERN Document Server

    Kirkby, Jasper

    2000-01-01

    Satellite observations have revealed a surprising imprint of the 11- year solar cycle on global low cloud cover. The cloud data suggest a correlation with the intensity of Galactic cosmic rays. If this apparent connection between cosmic rays and clouds is real, variations of the cosmic ray flux caused by long-term changes in the solar wind could have a significant influence on the global energy radiation budget and the climate. However a direct link between cosmic rays and clouds has not been unambiguously established and, moreover, the microphysical mechanism is poorly understood. New experiments are being planned to find out whether cosmic rays can affect cloud formation, and if so how. (37 refs).

  6. A Report of Clouds on Titan

    Science.gov (United States)

    Corlies, Paul; Hayes, Alexander; Adamkovics, Mate; Rodriguez, Sebastien; Kelland, John; Turtle, Elizabeth P.; Mitchell, Jonathan; Lora, Juan M.; Rojo, Patricio; Lunine, Jonathan I.

    2017-10-01

    We present in this work a detailed analysis of many of the clouds in the Cassini Visual and Infrared Mapping Spectrometer (VIMS) dataset in order to understand their global and seasonal properties. Clouds are one of the few direct observables in Titan’s atmosphere (Griffith et al 2009, Rodriguez et al 2009, Adamkovics et al 2010), and so determining their characteristics allows for a better understanding of surface atmosphere interactions, winds, transport of volatile material, and general circulation. We find the clouds on Titan generally reside in at 5-15km altitude, which agrees with previous modelling efforts (Rafkin et al. 2015), as well as a power law distribution for cloud optical depth. We assume an average cloud droplet size of 100um. No seasonal dependence is observed with either cloud altitude or optical depth, suggesting there is no preferred seasonal formation mechanisms. Combining these characteristics with cloud size (Kelland et al 2017) can trace the transport of volatiles in Titan’s atmosphere, which can be compared against general circulation models (GCMs) (Lora et al 2015). We also present some specific analysis of interesting cloud systems including hypothesized surface fogs (Brown et al 2009) and orographic cloud formation (Barth et al 2010, Corlies et al 2017). In this analysis we use a correlation between Cassini VIMS and RADAR observations as well as an updated topographic map of Titan’s southern hemisphere to better understand the role that topography plays in influencing and driving atmospheric phenomena.Finally, with the end of the Cassini mission, ground based observing now acts as the only means with which to observe clouds on Titan. We present an update of an ongoing cloud campaign to search for clouds on Titan and to understand their seasonal evolution.References:Adamkovics et al. 2010, Icarus 208:868Barth et al. 2010, Planet. Space Sci. 58:1740Corlies et al. 2017, 48th LPSC, 2870CGriffith et al. 2009, ApJ 702:L105Kelland et al

  7. Submm Observations of Massive Star Formation in the Giant Molecular Cloud NGC 6334 : Gas Kinematics with Radiative Transfer Models

    OpenAIRE

    Zernickel, Alexander

    2015-01-01

    Context. How massive stars (M>8 Ms) form and how they accrete gas is still an open research field, but it is known that their influence on the interstellar medium (ISM) is immense. Star formation involves the gravitational collapse of gas from scales of giant molecular clouds (GMCs) down to dense hot molecular cores (HMCs). Thus, it is important to understand the mass flows and kinematics in the ISM. Aims. This dissertation focuses on the detailed study of the region NGC 6334,...

  8. A global hybrid model for Mercury's interaction with the solar wind: Case study of the dipole representation

    OpenAIRE

    Richer, E.; Modolo, Ronan; Chanteur, G. M.; Hess, Sebastien; Leblanc, François

    2012-01-01

    International audience; The interaction of the solar wind (SW) with the magnetic field of Mercury is investigated by means of a three dimensional parallelized multispecies hybrid model. A comparison between two mathematical representations of Mercury's intrinsic magnetic field is studied. The first model is an Offset Dipole (OD) having the offset and dipolar moment reported by Anderson et al. (2011). The second model is a combination of a Dipole and a Quadrupole (DQ), the total field is fitte...

  9. Comparison of the Effects of Wave-Particle Interactions and the Kinetic Suprathermal Electron Population on the Acceleration of the Solar Wind

    Science.gov (United States)

    Tam, S. W. Y.; Chang, T.

    2002-01-01

    Kinetic effects due to wave-particle interactions and suprathermal electrons have been suggested in the literature as possible solar wind acceleration mechanisms. Ion cyclotron resonant heating, in particular, has been associated with some qualitative features observed in the solar wind. In terms of solar wind acceleration, however, it is interesting to compare the kinetic effects of suprathermal electrons with those due to the wave-particle interactions. The combined effects of the two acceleration mechanisms on the fast solar wind have been studied by Tam and Chang (1999a,b). In this study. we investigate the role of the suprathermal electron population in the acceleration of the solar wind. Our model follows the global kinetic evolution of the fast solar wind under the influence of ion cyclotron resonant heating, while taking into account Coulomb collisions, and the ambipolar electric field that is consistent with the particle distributions themselves. The kinetic effects due to the suprathermal electrons, which we define to be the tail of the electron distributions, can be included in the model as an option. By comparing the results with and without the inclusion of the suprathermal electron effects, we determine the relative importance of suprathermal electrons and wave-particle interactions in driving the solar wind. We find that although suprathermal electrons enhance the ambipolar electric potential in the solar wind considerably, their overall influence as an acceleration mechanism is relatively insignificant in a wave-driven solar wind.

  10. Reducing Bat Fatalities From Interactions with Operating Wind Turbines (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, M.

    2013-11-01

    One of the biggest advantages of wind energy is that, overall, it has fewer negative impacts on the environment than fossil fuel-generated energy. Most professionals in the wind industry would like to reduce the impact of energy generation on plants, animals, and their habitats. This is why the industry is highly motivated to find out why migrating bats have unexpectedly high fatality rates near operating wind farms. New research has provided quantitative data that indicates barotrauma is not a major cause of bat deaths around operating turbines.

  11. Exploring the Powerful Ionised Wind in the Seyfert Galaxy PG1211+143

    Science.gov (United States)

    Pounds, Ken

    2013-10-01

    Highly-ionised high-speed winds in AGN (UFOs) were first detected with XMM-Newton a decade ago, and are now established as a key factor in the study of SMBH accretion, and in the growth and metal enrichment of their host galaxies. However, information on the ionisation and dynamical structure, and the ultimate fate of UFOs remains very limited. We request a 600ks extended XMM-Newton study of the prototype UFO PG1211+143 in AO-13, to obtain high quality EPIC and RGS spectra, to map the flow structure and variability, while seeking evidence for the anticipated interaction with the ISM and possible conversion of the energetic wind to a momentum-driven flow.

  12. Dust-wind interactions can intensify aerosol pollution over eastern China

    Science.gov (United States)

    Yang, Yang; Russell, Lynn M.; Lou, Sijia; Liao, Hong; Guo, Jianping; Liu, Ying; Singh, Balwinder; Ghan, Steven J.

    2017-05-01

    Eastern China has experienced severe and persistent winter haze episodes in recent years due to intensification of aerosol pollution. In addition to anthropogenic emissions, the winter aerosol pollution over eastern China is associated with unusual meteorological conditions, including weaker wind speeds. Here we show, based on model simulations, that during years with decreased wind speed, large decreases in dust emissions (29%) moderate the wintertime land-sea surface air temperature difference and further decrease winds by -0.06 (+/-0.05) m s-1 averaged over eastern China. The dust-induced lower winds enhance stagnation of air and account for about 13% of increasing aerosol concentrations over eastern China. Although recent increases in anthropogenic emissions are the main factor causing haze over eastern China, we conclude that natural emissions also exert a significant influence on the increases in wintertime aerosol concentrations, with important implications that need to be taken into account by air quality studies.

  13. Mitigation of Wind Turbine/Vortex Interaction Using Disturbance Accommodating Control

    Energy Technology Data Exchange (ETDEWEB)

    Hand, M. M.

    2003-12-01

    Wind turbines, a competitive source of emission-free electricity, are being designed with diameters and hub heights approaching 100 m, to further reduce the cost of the energy they produce. At this height above the ground, the wind turbine is exposed to atmospheric phenomena such as low-level jets, gravity waves, and Kelvin-Helmholtz instabilities, which are not currently modeled in wind turbine design codes. These atmospheric phenomena can generate coherent turbulence that causes high cyclic loads on wind turbine blades. These fluctuating loads lead to fatigue damage accumulation and blade lifetime reduction. Advanced control was used to mitigate vortex-induced blade cyclic loading. A full-state feedback controller that incorporates more detailed vortex inputs achieved significantly greater blade load reduction. Blade loads attributed to vortex passage, then, can be reduced through advanced control, and further reductions appear feasible.

  14. WR 110: A Single Wolf-Rayet Star with Corotating Interaction Regions in its Wind?

    Science.gov (United States)

    Chené, A.-N.; Moffat, A. F. J.; Cameron, C.; Fahed, R.; Gamen, R. C.; Lefèvre, L.; Rowe, J. F.; St-louis, N.; Muntean, V.; De La Chevrotière, A.; Guenther, D. B.; Kuschnig, R.; Matthews, J. M.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.

    2011-07-01

    A 30 day contiguous photometric run with the Microvariability and Oscillations of STars (MOST) satellite on the WN5-6b star WR 110 (HD 165688) reveals a fundamental periodicity of P = 4.08 ± 0.55 days along with a number of harmonics at periods P/n, with n ≈ 2, 3, 4, 5, and 6, and a few other possible stray periodicities and/or stochastic variability on timescales longer than about a day. Spectroscopic radial velocity studies fail to reveal any plausible companion with a period in this range. Therefore, we conjecture that the observed light-curve cusps of amplitude ~0.01 mag that recur at a 4.08 day timescale may arise in the inner parts, or at the base, of a corotating interaction region (CIR) seen in emission as it rotates around with the star at constant angular velocity. The hard X-ray component seen in WR 110 could then be a result of a high velocity component of the CIR shock interacting with the ambient wind at several stellar radii. Given that most hot, luminous stars showing CIRs have two CIR arms, it is possible that either the fundamental period is 8.2 days or, more likely in the case of WR 110, there is indeed a second weaker CIR arm for P = 4.08 days, that occurs ~two-thirds of a rotation period after the main CIR. If this interpretation is correct, WR 110 therefore joins the ranks with three other single WR stars, all WN, with confirmed CIR rotation periods (WR 1, WR 6, and WR 134), albeit with WR 110 having by far the lowest amplitude photometric modulation. This illustrates the power of being able to secure intense, continuous high-precision photometry from space-based platforms such as MOST. It also opens the door to revealing low-amplitude photometric variations in other WN stars, where previous attempts have failed. If all WN stars have CIRs at some level, this could be important for revealing sources of magnetism or pulsation in addition to rotation periods. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly

  15. Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet with Shock Interactions

    Science.gov (United States)

    Cliff, Susan E.; Denison, Marie; Sozer, Emre; Moini-Yekta, Shayan

    2016-01-01

    NASA and Industry are performing vehicle studies of configurations with low sonic boom pressure signatures. The computational analyses of modern configuration designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty in the aft signatures with often greater boundary layer effects and nozzle jet pressures. Wind tunnel testing at significantly lower Reynolds numbers than in flight and without inlet and nozzle jet pressures make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel from Mach 1.6 to 2.0 will be used to assess the effects of shocks from components passing through nozzle jet plumes on the sonic boom pressure signature and provide datasets for comparison with CFD codes. A large number of high-fidelity numerical simulations of wind tunnel test models with a variety of shock generators that simulate horizontal tails and aft decks have been studied to provide suitable models for sonic boom pressure measurements using a minimally intrusive pressure rail in the wind tunnel. The computational results are presented and the evolution of candidate wind tunnel models is summarized and discussed in this paper.

  16. THE INTERACTION OF VENUS-LIKE, M-DWARF PLANETS WITH THE STELLAR WIND OF THEIR HOST STAR

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, O.; Drake, J. J.; Garraffo, C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St. Cambridge, MA 02138 (United States); Ma, Y. [Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, California (United States); Glocer, A. [NASA/GSFC, Code 673 Greenbelt, MD 20771 (United States); Bell, J. M. [Center for Planetary Atmospheres and Flight Sciences, National Institute of Aerospace, Hampton, VA 23666 (United States); Gombosi, T. I. [Center for Space Environment Modeling, University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109 (United States)

    2015-06-10

    We study the interaction between the atmospheres of Venus-like, non-magnetized exoplanets orbiting an M-dwarf star, and the stellar wind using a multi-species MHD model. We focus our investigation on the effect of enhanced stellar wind and enhanced EUV flux as the planetary distance from the star decreases. Our simulations reveal different topologies of the planetary space environment for sub- and super-Alfvénic stellar wind conditions, which could lead to dynamic energy deposition into the atmosphere during the transition along the planetary orbit. We find that the stellar wind penetration for non-magnetized planets is very deep, up to a few hundreds of kilometers. We estimate a lower limit for the atmospheric mass-loss rate and find that it is insignificant over the lifetime of the planet. However, we predict that when accounting for atmospheric ion acceleration, a significant amount of the planetary atmosphere could be eroded over the course of a billion years.

  17. Open and partially closed models of the solar wind interaction with outer planet magnetospheres: the case of Saturn

    Directory of Open Access Journals (Sweden)

    E. S. Belenkaya

    2017-12-01

    Full Text Available A wide variety of interactions take place between the magnetized solar wind plasma outflow from the Sun and celestial bodies within the solar system. Magnetized planets form magnetospheres in the solar wind, with the planetary field creating an obstacle in the flow. The reconnection efficiency of the solar-wind-magnetized planet interaction depends on the conditions in the magnetized plasma flow passing the planet. When the reconnection efficiency is very low, the interplanetary magnetic field (IMF does not penetrate the magnetosphere, a condition that has been widely discussed in the recent literature for the case of Saturn. In the present paper, we study this issue for Saturn using Cassini magnetometer data, images of Saturn's ultraviolet aurora obtained by the HST, and the paraboloid model of Saturn's magnetospheric magnetic field. Two models are considered: first, an open model in which the IMF penetrates the magnetosphere, and second, a partially closed model in which field lines from the ionosphere go to the distant tail and interact with the solar wind at its end. We conclude that the open model is preferable, which is more obvious for southward IMF. For northward IMF, the model calculations do not allow us to reach definite conclusions. However, analysis of the observations available in the literature provides evidence in favor of the open model in this case too. The difference in magnetospheric structure for these two IMF orientations is due to the fact that the reconnection topology and location depend on the relative orientation of the IMF vector and the planetary dipole magnetic moment. When these vectors are parallel, two-dimensional reconnection occurs at the low-latitude neutral line. When they are antiparallel, three-dimensional reconnection takes place in the cusp regions. Different magnetospheric topologies determine different mapping of the open-closed boundary in the ionosphere, which can be considered as a proxy for the

  18. Non-steady dynamics of atmospheric turbulence interaction with wind turbine loadings through blade-boundary-layer-resolved CFD

    Science.gov (United States)

    Vijayakumar, Ganesh

    Modern commercial megawatt-scale wind turbines occupy the lower 15-20% of the atmospheric boundary layer (ABL), the atmospheric surface layer (ASL). The current trend of increasing wind turbine diameter and hub height increases the interaction of the wind turbines with the upper ASL which contains spatio-temporal velocity variations over a wide range of length and time scales. Our interest is the interaction of the wind turbine with the energetic integral-scale eddies, since these cause the largest temporal variations in blade loadings. The rotation of a wind turbine blade through the ABL causes fluctuations in the local velocity magnitude and angle of attack at different sections along the blade. The blade boundary layer responds to these fluctuations and in turn causes temporal transients in local sectional loads and integrated blade and shaft bending moments. While the integral scales of the atmospheric boundary layer are ˜ O(10--100m) in the horizontal with advection time scales of order tens of seconds, the viscous surface layer of the blade boundary layer is ˜ O(10 -- 100 mum) with time scales of order milliseconds. Thus, the response of wind turbine blade loadings to atmospheric turbulence is the result of the interaction between two turbulence dynamical systems at extremely disparate ranges of length and time scales. A deeper understanding of this interaction can impact future approaches to improve the reliability of wind turbines in wind farms, and can underlie future improvements. My thesis centers on the development of a computational framework to simulate the interaction between the atmospheric and wind turbine blade turbulence dynamical systems using a two step one-way coupled approach. Pseudo-spectral large eddy simulation (LES) is used to generate a true (equilibrium) atmospheric boundary layer over a flat land with specified surface roughness and heating consistent with the stability state of the daytime lower troposphere. Using the data from the

  19. Sequential Convex Programming for Power Set-point Optimization in a Wind Farm using Black-box Models, Simple Turbine Interactions, and Integer Variables

    DEFF Research Database (Denmark)

    Hovgaard, Tobias Gybel; Larsen, Lars F. S.; Jørgensen, John Bagterp

    2012-01-01

    from the wind farm model, enabling us to use a very simple linear relationship for describing the turbine interactions. In addition, we allow individual turbines to be turned on or off introducing integer variables into the optimization problem. We solve this within the same framework of iterative......We consider the optimization of power set-points to a large number of wind turbines arranged within close vicinity of each other in a wind farm. The goal is to maximize the total electric power extracted from the wind, taking the wake effects that couple the individual turbines in the farm...... into account. For any mean wind speed, turbulence intensity, and direction we find the optimal static operating points for the wind farm. We propose an iterative optimization scheme to achieve this goal. When the complicated, nonlinear, dynamics of the aerodynamics in the turbines and of the fluid dynamics...

  20. The interaction between the solar wind and the heterogeneous neutral gas coma of comet 67P/Churyumov-Gerasimenko

    Science.gov (United States)

    Rubin, Martin; Toth, Gabor; Tenishev, Valeriy; Fougere, Nicolas; Huang, Zhenguang

    2016-07-01

    Comets are surrounded by an extended gas and dust coma. Neutral particles are continuously ionized by solar irradiation and then picked-up by the solar wind. This leads to a complex interaction between the neutral gas coma and the solar wind, which changes over the course of the comet's orbit around the Sun. The European Space Agency's Rosetta spacecraft has been in orbit around comet 67P/Churyumov-Gerasimenko since August 2014. Rosetta carries several instruments to investigate the comet's nucleus and surrounding neutral gas coma and plasma. Part of the payload is the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) that consists of two mass spectrometers and a pressure sensor. ROSINA was designed to measure the neutral gas abundance and composition and low energy ions in the coma in situ. ROSINA observations have shown that the coma is very heterogeneous both in total density and composition of the neutral gas. This heterogeneity is driven in large part by the complex shape of the nucleus and the varying illumination conditions associated with the comet's rotation. In this presentation we will show the time-dependent distribution of the major volatiles around the comet constrained by ROSINA observations. Furthermore we will investigate the impact of the highly non-symmetric neutral gas coma on the interaction of the solar wind with the comet.

  1. Solar wind electron interaction with the dayside lunar surface and crustal magnetic fields: Evidence for precursor effects

    Science.gov (United States)

    Halekas, J. S.; Poppe, A.; Delory, G. T.; Farrell, W. M.; Horányi, M.

    2012-02-01

    Electron distributions measured by Lunar Prospector above the dayside lunar surface in the solar wind often have an energy dependent loss cone, inconsistent with adiabatic magnetic reflection. Energy dependent reflection suggests the presence of downward parallel electric fields below the spacecraft, possibly indicating the presence of a standing electrostatic structure. Many electron distributions contain apparent low energy (<100 eV) upward-going conics (58% of the time) and beams (12% of the time), primarily in regions with non-zero crustal magnetic fields, implying the presence of parallel electric fields and/or wave-particle interactions below the spacecraft. Some, but not all, of the observed energy dependence comes from the energy gained during reflection from a moving obstacle; correctly characterizing electron reflection requires the use of the proper reference frame. Non-adiabatic reflection may also play a role, but cannot fully explain observations. In cases with upward-going beams, we observe partial isotropization of incoming solar wind electrons, possibly indicating streaming and/or whistler instabilities. The Moon may therefore influence solar wind plasma well upstream from its surface. Magnetic anomaly interactions and/or non-monotonic near surface potentials provide the most likely candidates to produce the observed precursor effects, which may help ensure quasi-neutrality upstream from the Moon.

  2. Investigation of the Air-Wave-Sea Interaction Modes Using an Airborne Doppler Wind Lidar: Analyses of the HRDL Data Taken using DYNAMO

    Science.gov (United States)

    2013-10-07

    Interaction Modes Using an Airborne Doppler Wind Lidar: Analyses of the HRDL data taken using DYNAMO 5a. CONTRACT NUMBER N0001411C0464 5b. GRANT...efficiency of energy, mass and momentum exchange at the bottom and top of the ABL. 15. SUBJECT TERMS DYNAMO , ABL 16. SECURITY CLASSIFICATION OF: 17...Investigation of the Air-Wave-Sea Interaction Modes Using an Airborne Doppler Wind Lidar: Analyses of the HRDL data taken during DYNAMO George

  3. Surface melt on Antarctic ice shelves driven by wind-albedo interactions

    Science.gov (United States)

    Lhermitte, Stef; Lenaerts, Jan

    2017-04-01

    Surface melt and subsequent firn air depletion is considered an important precursor for disintegration of Antarctic ice shelves, causing grounded glaciers to accelerate and sea level to rise. Recent studies have highlighted the impact of surface winds on Antarctic ice shelf melt, both on the Antarctic Peninsula and in East Antarctica. In the Antarctic Peninsula, foehn winds enhance melting near the grounding line, which in the recent past has led to the disintegration of the most northerly ice shelves. On the East Antarctic ice shelves, on the other hand, meltwater-induced firn air depletion is found in the grounding zone as result of persistent katabatic winds, regionally warming the atmosphere and inducing a melt-albedo feedback. Here, we use a combination multi-source satellite imagery, snow modelling, climate model output and in-situ observations to highlight the importance of this wind-induced melt and to show its widespread occurrence across Antarctica. The satellite imagery gives insight in the meltwater drainage systems, showing spatio-temporal changes in both supraglacial and englacial water throughout the melt season and during the subsequent winter. Although the wind-induced melt is a regional phenomenon with strong inter-annual variability, it is strongly correlated to larger scale climate parameters, such as summer surface temperature. Based on these correlations and snow model output driven by future climate scenarios, we can constrain the future changes to this local melt near the grounding line.

  4. Numerical simulation and transonic wind-tunnel test for elastic thin-shell structure considering fluid–structure interaction

    Directory of Open Access Journals (Sweden)

    Yunju Yan

    2015-02-01

    Full Text Available Aerodynamic force can lead to the strong structural vibration of flying aircraft at a high speed. This harmful vibration can bring damage or failure to the electronic equipment fixed in aircraft. It is necessary to predict the structural dynamic response in the design course. This paper presents a new numerical algorithm and scheme to solve the structural dynamics responses when considering fluid–structure interaction (FSI. Numerical simulation for a free-flying structural model in transonic speed is completed. Results show that the small elastic deformation of the structure can greatly affect the FSI. The FSI vibration tests are carried out in a transonic speed wind-tunnel for checking numerical theory and algorithms, and the wind-tunnel test results well accord with that of the numerical simulation. This indicates that the presented numerical method can be applied to predicting the structural dynamics responses when containing the FSI.

  5. Ice Formation and Growth in Orographically-Enhanced Mixed-Phase Clouds

    Science.gov (United States)

    David, Robert; Lowenthal, Douglas; Gannet Hallar, A.; McCubbin, Ian; Avallone, Linnea; Mace, Gerald; Wang, Zhien

    2015-04-01

    The formation and evolution of ice in mixed-phase clouds continues to be an active area of research due to the complex interactions between vapor, liquid and ice. Orographically-enhanced clouds are commonly mixed-phase during winter. An airborne study, the Colorado Airborne Mixed-Phase Cloud Study (CAMPS), and a ground-based field campaign, the Storm Peak Lab (SPL) Cloud Property Validation Experiment (StormVEx) were conducted in the Park Range of the Colorado Rockies. The CAMPS study utilized the University of Wyoming King Air (UWKA) to provide airborne cloud microphysical and meteorological data on 29 flights totaling 98 flight hours over the Park Range from December 15, 2010 to February 28, 2011. The UWKA was equipped with instruments that measured both cloud droplet and ice crystal size distributions, liquid water content, total water content (vapor, liquid, and ice), and 3-dimensional wind speed and direction. The Wyoming Cloud Radar and Lidar were also deployed during the campaign. These measurements are used to characterize cloud structure upwind and above the Park Range. StormVEx measured temperature, and cloud droplet and ice crystal size distributions at SPL. The observations from SPL are used to determine mountain top cloud microphysical properties at elevations lower than the UWKA was able to sample in-situ. Comparisons showed that cloud microphysics aloft and at the surface were consistent with respect to snow growth processes. Small ice crystal concentrations were routinely higher at the surface and a relationship between small ice crystal concentrations, large cloud droplet concentrations and temperature was observed, suggesting liquid-dependent ice nucleation near cloud base. Terrain flow effects on cloud microphysics and structure are considered.

  6. Highly Compact MIMO Antenna System for LTE/ISM Applications

    Directory of Open Access Journals (Sweden)

    Lingsheng Yang

    2015-01-01

    Full Text Available Planar monopole antenna is proposed as the antenna element to form a compact dual-element multiple-input-multiple-output (MIMO antenna system for LTE2300 (used in Asia and Africa and ISM band operation. The system can cover a 310 MHz (2.20–2.51 GHz operating bandwidth, with the total size of 15.5 mm × 18 mm × 1.6 mm. Measured isolation higher than 16 dB is obtained without any specially designed decoupling structures, while the edge-to-edge element spacing is only 7.8 mm (0.08λ at 2.20 GHz. Radiation characteristics, correlation coefficient, and the performance of the whole system with a metal sheet and a plastic housing show this system is competitive for practical MIMO applications. The antenna element is further used to build an eight-element MIMO antenna system; also good results are achieved.

  7. Anomalous Faraday rotation in the ISM/ICM

    Science.gov (United States)

    Medvedev, Mikhail V.

    2016-10-01

    Faraday effect is a common and useful way to deduce cosmic magnetic fields in the interstellar and intracluster media (ISM and ICM). Faraday rotation is the result of magnetically-induced birefringence in a dielectric medium causing a linearly polarized wave to suffer a rotation of its polarization axis as it traverses such a medium. However, the standard λ2-law of the rotation angle may not hold in strongly turbulent plasmas. Electromagnetic high-frequency and/or small-scale fluctuations may lead to effective collisionality with the pitch-angle diffusion coefficient being an effective ``quasi-collision'' frequency. Recently, we showed that quasi-collisionality may radically alter radiative transport properties of plasmas, such as absorption, transmission and reflection and other effects, which can be very important in laboratory and astrophysical plasmas. Here we briefly discuss the quasi-collisional generalization of the classical Faraday effect, which is drastically modified and can even become negative. Furthermore, we explore the origin of the long-known anomaly of Faraday rotation in a famous Cygnus regions. We argue that the anomaly can be due to the anomalous Faraday rotation in a thin ``blanket'' of turbulent plasma at the front of an interstellar bubble/shock. Supported by KU CLAS and DOE Grant ID0000225143 (07/01/16).

  8. Changes in future air quality, deposition, and aerosol-cloud interactions under future climate and emission scenarios

    Science.gov (United States)

    Glotfelty, Timothy; Zhang, Yang; Karamchandani, Prakash; Streets, David G.

    2016-08-01

    The prospect of global climate change will have wide scale impacts, such as ecological stress and human health hazards. One aspect of concern is future changes in air quality that will result from changes in both meteorological forcing and air pollutant emissions. In this study, the GU-WRF/Chem model is employed to simulate the impact of changing climate and emissions following the IPCC AR4 SRES A1B scenario. An average of 4 future years (2020, 2030, 2040, and 2050) is compared against an average of 2 current years (2001 and 2010). Under this scenario, by the Mid-21st century global air quality is projected to degrade with a global average increase of 2.5 ppb in the maximum 8-hr O3 level and of 0.3 μg m-3 in 24-hr average PM2.5. However, PM2.5 changes are more regional due to regional variations in primary aerosol emissions and emissions of gaseous precursor for secondary PM2.5. Increasing NOx emissions in this scenario combines with a wetter climate elevating levels of OH, HO2, H2O2, and the nitrate radical and increasing the atmosphere's near surface oxidation state. This differs from findings under the RCP scenarios that experience declines in OH from reduced NOx emissions, stratospheric recovery of O3, and increases in CH4 and VOCs. Increasing NOx and O3 levels enhances the nitrogen and O3 deposition, indicating potentially enhanced crop damage and ecosystem stress under this scenario. The enhanced global aerosol level results in enhancements in aerosol optical depth, cloud droplet number concentration, and cloud optical thickness. This leads to dimming at the Earth's surface with a global average reduction in shortwave radiation of 1.2 W m-2. This enhanced dimming leads to a more moderate warming trend and different trends in radiation than those found in NCAR's CCSM simulation, which does not include the advanced chemistry and aerosol treatment of GU-WRF/Chem and cannot simulate the impacts of changing climate and emissions with the same level of detailed

  9. Weaving the history of the solar wind with magnetic field lines

    Science.gov (United States)

    Alvarado Gomez, Julian

    2017-08-01

    Despite its fundamental role for the evolution of the solar system, our observational knowledge of the wind properties of the young Sun comes from a single stellar observation. This unexpected fact for a field such as astrophysics arises from the difficulty of detecting Sun-like stellar winds. Their detection relies on the appearance of an astrospheric signature (from the stellar wind-ISM interaction region), visible only with the aid of high-resolution HST Lyman-alpha spectra. However, observations and modelling of the present day Sun have revealed that magnetic fields constitute the main driver of the solar wind, providing guidance on how such winds would look like back in time. In this context we propose observations of four young Sun-like stars in order to detect their astrospheres and characterise their stellar winds. For all these objects we have recovered surface magnetic field maps using the technique of Zeeman Doppler Imaging, and developed detailed wind models based on these observed field distributions. Even a single detection would represent a major step forward for our understanding of the history of the solar wind, and the outflows in more active stars. Mass loss rate estimates from HST will be confronted with predictions from realistic models of the corona/stellar wind. In one of our objects the comparison would allow us to quantify the wind variability induced by the magnetic cycle of a star, other than the Sun, for the first time. Three of our targets are planet hosts, thus the HST spectra would also provide key information on the high-energy environment of these systems, guaranteeing their legacy value for the growing field of exoplanet characterisation.

  10. CWEX: Crop/wind-energy experiment: Observations of surface-layer, boundary-layer and mesoscale interactions with a wind farm

    Science.gov (United States)

    Large wind turbines perturb mean and turbulent wind characteristics, which modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could create significant changes in surface fluxes of heat, momentum, moisture, and CO2 over hundreds ...

  11. Crop/Wind-energy Experiment (CWEX): Observations of surface-layer, boundary-layer and mesoscale interactions with a wind farm

    Science.gov (United States)

    Perturbations of mean and turbulent wind characteristics by large wind turbines modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could significantly change surface fluxes of heat, momentum, moisture, and CO2 over hundreds of s...

  12. Simulation of Mini-Magnetospheric Plasma Propulsion (M2P2) Interacting with an External Plasma Wind

    Science.gov (United States)

    Winglee, R. M.; Euripides, P.; Ziemba, T.; Slough, J.; Giersch, L.

    2003-01-01

    Substantial progress has been made over the last year in the development of the laboratory Mini-Magnetospheric Plasma Propulsion (M2P2) prototype. The laboratory testing has shown that that the plasma can be produced at high neutral gas efficiency, at high temperatures (a few tens of eV) with excellent confinement up to the point where chamber wall interactions dominate the physics. This paper investigates the performance of the prototype as it is opposed by an external plasma acting as a surrogate for the solar wind. The experiments were performed in 5ft diameter by 6ft long vacuum chamber at the University of Washington. The solar wind source comprised of a 33 kWe arc jet attached to a 200 kWe inductively generated plasma source. The dual plasma sources allow the interaction to be studied for different power levels, shot duration and production method. It is shown that plasma from the solar wind source (SWS) is able to penetrate the field of the M2P2 magnetic when no plasma is present. With operation of the M2P2 plasma source at only 1.5 kWe, the penetration of the SWS even at the highest power of operation at 200 kWe is stopped. This deflection is shown to be greatly enhanced over that produced by the magnet alone. In addition it is shown that with the presence of the SWS, M2P2 is able to produce enhanced magnetized plasma production out to at least 10 magnet radii where the field strength is only marginally greater than the terrestrial field. The results are consistent with the initial predictions that kWe M2P2 systems would be able to deflect several hundred kWe plasma winds to produce enhanced propulsion for a spacecraft.

  13. Impact of future climate policy scenarios on air quality and aerosol-cloud interactions using an advanced version of CESM/CAM5: Part I. model evaluation for the current decadal simulations

    Science.gov (United States)

    Glotfelty, Timothy; He, Jian; Zhang, Yang

    2017-03-01

    A version of the Community Earth System Model modified at the North Carolina State University (CESM-NCSU) is used to simulate the current and future atmosphere following the representative concentration partway scenarios for stabilization of radiative forcing at 4.5 W m-2 (RCP4.5) and radiative forcing of 8.5 W m-2 (RCP8.5). Part I describes the results from a comprehensive evaluation of current decadal simulations. Radiation and most meteorological variables are well simulated in CESM-NCSU. Cloud parameters are not as well simulated due in part to the tuning of model radiation and general biases in cloud variables common to all global chemistry-climate models. The concentrations of most inorganic aerosol species (i.e., SO42-, NH4+, and NO3-) are well simulated with normalized mean biases (NMBs) typically less than 20%. However, some notable exceptions are European NH4+, which is overpredicted by 33.0-42.2% due to high NH3 emissions and irreversible coarse mode condensation, and Cl-, that is negatively impacted by errors in emissions driven by wind speed and overpredicted HNO3. Carbonaceous aerosols are largely underpredicted following the RCP scenarios due to low emissions of black carbon, organic carbon, and anthropogenic volatile compounds in the RCP inventory and efficient wet removal. This results in underpredictions of PM2.5 and PM10 by 6.4-55.7%. The column mass abundances are reasonably well simulated. Larger biases occur in surface mixing ratios of trace gases in CESM-NCSU, likely due to numerical diffusion from the coarse grid spacing of the CESM-NCSU simulations or errors in the magnitudes and vertical structure of emissions. This is especially true for SO2 and NO2. The mixing ratio of O3 is overpredicted by 38.9-76.0% due to the limitations in the O3 deposition scheme used in CESM and insufficient titration resulted from large underpredictions in NO2. Despite these limitations, CESM-NCSU reproduces reasonably well the current atmosphere in terms of

  14. Lukács : un athéisme problématique

    OpenAIRE

    Charbonnier, Vincent

    2000-01-01

    Quoique Lukács n'ait pas explicitement thématisé la question de l'athéisme, nous nous demanderons si le tragique qui façonne ses premières œuvres ne recèle pas, en définitive, un athéisme implicite. Plus précisément, ne s'agit-il pas d'un athéisme d'abord vécu, sur le mode négatif (au sens hégélien), d'un retrait des dieux, athéisme qui sera, par la suite, positivement retourné (comme un gant), en un messianisme eschatologique - comme immanence du ciel à la terre - dont le prolétariat serait/...

  15. Interactions between aerosol absorption, thermodynamics, dynamics, and microphysics and their impacts on a multiple-cloud system

    Science.gov (United States)

    Lee, Seoung Soo; Li, Zhanqing; Mok, Jungbin; Ahn, Myoung-Hwan; Kim, Byung-Gon; Choi, Yong-Sang; Jung, Chang-Hoon; Yoo, Hye Lim

    2017-12-01

    This study investigates how the increasing concentration of black carbon aerosols, which act as radiation absorbers as well as agents for the cloud-particle nucleation, affects stability, dynamics and microphysics in a multiple-cloud system using simulations. Simulations show that despite increases in stability due to increasing concentrations of black carbon aerosols, there are increases in the averaged updraft mass fluxes (over the whole simulation domain and period). This is because aerosol-enhanced evaporative cooling intensifies convergence near the surface. This increase in the intensity of convergence induces an increase in the frequency of updrafts with the low range of speeds, leading to the increase in the averaged updraft mass fluxes. The increase in the frequency of updrafts induces that in the number of condensation entities and this leads to more condensation and cloud liquid that acts to be a source of the accretion of cloud liquid by precipitation. Hence, eventually, there is more accretion that offsets suppressed autoconversion, which results in negligible changes in cumulative precipitation as aerosol concentrations increase. The increase in the frequency of updrafts with the low range of speeds alters the cloud-system organization (represented by cloud-depth spatiotemporal distributions and cloud-cell population) by supporting more low-depth clouds. The altered organization in turn alters precipitation spatiotemporal distributions by generating more weak precipitation events. Aerosol-induced reduction in solar radiation that reaches the surface induces more occurrences of small-value surface heat fluxes, which in turn supports the more low-depth clouds and weak precipitation together with the greater occurrence of low-speed updrafts.

  16. Interactions between aerosol absorption, thermodynamics, dynamics, and microphysics and their impacts on a multiple-cloud system

    Science.gov (United States)

    Lee, Seoung Soo; Li, Zhanqing; Mok, Jungbin; Ahn, Myoung-Hwan; Kim, Byung-Gon; Choi, Yong-Sang; Jung, Chang-Hoon; Yoo, Hye Lim

    2017-02-01

    This study investigates how the increasing concentration of black carbon aerosols, which act as radiation absorbers as well as agents for the cloud-particle nucleation, affects stability, dynamics and microphysics in a multiple-cloud system using simulations. Simulations show that despite increases in stability due to increasing concentrations of black carbon aerosols, there are increases in the averaged updraft mass fluxes (over the whole simulation domain and period). This is because aerosol-enhanced evaporative cooling intensifies convergence near the surface. This increase in the intensity of convergence induces an increase in the frequency of updrafts with the low range of speeds, leading to the increase in the averaged updraft mass fluxes. The increase in the frequency of updrafts induces that in the number of condensation entities and this leads to more condensation and cloud liquid that acts to be a source of the accretion of cloud liquid by precipitation. Hence, eventually, there is more accretion that offsets suppressed autoconversion, which results in negligible changes in cumulative precipitation as aerosol concentrations increase. The increase in the frequency of updrafts with the low range of speeds alters the cloud-system organization (represented by cloud-depth spatiotemporal distributions and cloud-cell population) by supporting more low-depth clouds. The altered organization in turn alters precipitation spatiotemporal distributions by generating more weak precipitation events. Aerosol-induced reduction in solar radiation that reaches the surface induces more occurrences of small-value surface heat fluxes, which in turn supports the more low-depth clouds and weak precipitation together with the greater occurrence of low-speed updrafts.

  17. ISMS: A New Model for Improving Student Motivation and Self-esteem in Primary Education

    OpenAIRE

    Yaron GHILAY; Ruth GHILAY

    2015-01-01

    In this study we introduce a new model for primary education called ISMS: Improving Student Motivation and Self-esteem. Following a two-year study undertaken in a primary school (n=67), the new model was found to be successful. Students who participated in the research, reported that a course based on ISMS principles was very helpful for strengthening their perceived ability and their motivation to make an effort. They became more enthusiastic, responsible, self-confident, optimistic and dete...

  18. Wind turbine inverter robust loop-shaping control subject to grid interaction effects

    DEFF Research Database (Denmark)

    Gryning, Mikkel Peter Sidoroff; Wu, Qiuwei; Blanke, Mogens

    2015-01-01

    with integral effect while bounding the induced change. The design was tested in an aggregated model of the London Array offshore wind power plant and compared with traditional PI controller designs. Robust stability and performance and a reduction of control effort by 25% are obtained over the full envelope...

  19. Validation of a three-dimensional viscous-inviscid interactive solver for wind turbine rotors

    DEFF Research Database (Denmark)

    Ramos García, Néstor; Sørensen, Jens Nørkær; Shen, Wen Zhong

    2014-01-01

    MIRAS is a newly developed computational model that predicts the aerodynamic behavior of wind turbine blades and wakes subject to unsteady motions and viscous effects. The model is based on a three-dimensional panel method using a surface distribution of quadrilateral singularities with a Neumann...

  20. Wake interaction and power production of variable height model wind farms

    DEFF Research Database (Denmark)

    Vested, Malene Hovgaard; Hamilton, N.; Sørensen, Jens Nørkær

    2014-01-01

    of comparison. It was found that downstream of the exit row wind turbine, the power was increased by 25% in the case of a staggered height configuration. This is partly due to the fact that the taller turbines reach into a flow area with a softened velocity gradient. Another aspect is that the wake downstream...

  1. Conceptions of Tornado Wind Speed and Land Surface Interactions among Undergraduate Students in Nebraska

    Science.gov (United States)

    Van Den Broeke, Matthew S.; Arthurs, Leilani

    2015-01-01

    To ascertain novice conceptions of tornado wind speed and the influence of surface characteristics on tornado occurrence, 613 undergraduate students enrolled in introductory science courses at a large state university in Nebraska were surveyed. Our findings show that students lack understanding of the fundamental concepts that (1) tornadoes are…

  2. Laboratory modelling of the wind-wave interaction with modified PIV-method

    Science.gov (United States)

    Sergeev, Daniil; Kandaurov, Alexander; Troitskaya, Yuliya; Caulliez, Guillemette; Bopp, Maximilian; Jaehne, Bernd

    Laboratory experiments on studying the structure of the turbulent air boundary layer over waves were carried out at the Wind-Wave Flume of the Large Thermostratified Tank of the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS), in conditions modeling the near water boundary layer of the atmosphere under strong and hurricane winds and the equivalent wind velocities from 10 to 48 m/s at the standard height of 10 m. A modified technique of Particle Image Velocimetry (PIV) was used to obtain turbulent pulsation averaged velocity fields of the air flow over the water surface curved by a wave and average profiles of the wind velocity. The main modifications are: 1) the use of high-speed video recording (1000-10000 frames/sec) with continuous laser illumination helps to obtain ensemble of the velocity fields in all phases of the wavy surface for subsequent statistical processing; 2) the development and application of special algorithms for obtaining form of the curvilinear wavy surface of the images for the conditions of parasitic images of the particles and the droplets in the air side close to the surface; 3) adaptive cross-correlation image processing to finding the velocity fields on a curved grid, caused by wave boarder; 4) using Hilbert transform to detect the phase of the wave in which the measured velocity field for subsequent appropriate binning within procedure obtaining the average characteristics.

  3. Laboratory modelling of the wind-wave interaction with modified PIV-method

    Directory of Open Access Journals (Sweden)

    Sergeev Daniil

    2017-01-01

    Full Text Available Laboratory experiments on studying the structure of the turbulent air boundary layer over waves were carried out at the Wind-Wave Flume of the Large Thermostratified Tank of the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS, in conditions modeling the near water boundary layer of the atmosphere under strong and hurricane winds and the equivalent wind velocities from 10 to 48 m/s at the standard height of 10 m. A modified technique of Particle Image Velocimetry (PIV was used to obtain turbulent pulsation averaged velocity fields of the air flow over the water surface curved by a wave and average profiles of the wind velocity. The main modifications are: 1 the use of high-speed video recording (1000-10000 frames/sec with continuous laser illumination helps to obtain ensemble of the velocity fields in all phases of the wavy surface for subsequent statistical processing; 2 the development and application of special algorithms for obtaining form of the curvilinear wavy surface of the images for the conditions of parasitic images of the particles and the droplets in the air side close to the surface; 3 adaptive cross-correlation image processing to finding the velocity fields on a curved grid, caused by wave boarder; 4 using Hilbert transform to detect the phase of the wave in which the measured velocity field for subsequent appropriate binning within procedure obtaining the average characteristics.

  4. Differential stemflow generation due to crown structural interactions with wind-driven rainfall

    Science.gov (United States)

    Van Stan, John; Siegert, Courtney; Levia, Delphis; Scheick, Carrie

    2013-04-01

    Meteorological influences on the variability of stemflow generation can affect the hydrology, ecology and soil chemistry of wooded ecosystems, yet the effects of directional wind-driven rainfall on differential stemflow production remain relatively un-researched. This study examines the correspondence of directional wind-driven inclined rainfall with stemflow generation in individual tree crowns utilizing multiple correspondence analysis (MCA) and intrastorm observations at 5 min monitoring intervals. In general, preferential stemflow generation at Fair Hill was observed during episodes of inclined rainfall driven by wind from the east to north-northeast (33.76-101.25 deg.). This was supported by MCAs which produced significant correspondences between stemflow production and periods of inclined wind-driven rainfall for nearly all monitored storm events. Intrastorm plots of stemflow production from dominant and subcanopy trees of each codominant species (Fagus grandifolia Ehrh. (American beech) and Liriodendron tulipifera L. (yellow poplar)) also verified this correspondence. Interspecific canopy characteristics of L. tulipifera and F. grandifolia affected crown position, canopy structural characteristics, and, thus, the canopy's response to inclined precipitation. The greater vertical canopy depth observed for F. grandifolia trees enabled them to more efficiently capture inclined rainfall for enhanced stemflow production; whereas, the greater horizontal surface area of L. tulipifera canopies enhanced their droplet capture efficiency and subsequent stemflow generation for periods of un-inclined rainfall. As inclined wind-driven rainfall occurred within a majority of rain events at this site, preferential stemflow production may be a significant process to consider when examining the spatial distribution of canopy-derived water fluxes to the forest floor of wooded catchments under similar meteorological conditions.

  5. Competing mechanisms of plasma transport in inhomogeneous configurations with velocity shear: the solar-wind interaction with earth's magnetosphere.

    Science.gov (United States)

    Faganello, M; Califano, F; Pegoraro, F

    2008-01-11

    Two-dimensional simulations of the Kelvin-Helmholtz instability in an inhomogeneous compressible plasma with a density gradient show that, in a transverse magnetic field configuration, the vortex pairing process and the Rayleigh-Taylor secondary instability compete during the nonlinear evolution of the vortices. Two different regimes exist depending on the value of the density jump across the velocity shear layer. These regimes have different physical signatures that can be crucial for the interpretation of satellite data of the interaction of the solar wind with the magnetospheric plasma.

  6. 3D, Multi-fluid, MHD Calculations of the Solar Wind Interaction with Mars and the Associated Plasma Escape.

    Science.gov (United States)

    Najib, D.; Nagy, A.; Toth, G.; Ma, Y.-J.

    2009-04-01

    We have used our new 3D, multi-fluid, MHD model to study the interaction of the solar wind with Mars. Our lower boundary is set at 100 km and we have a radial grid resolution of about 10 km in the ionosphere. We consider both photo and electron impact ionization, as well as charge exchange processes. We compare a number of calculated and measured parameters, such as bow shock and MPB locations. We also calculate the plasma escape fluxes, for a variety of solar and upstream conditions. We compare our calculated escape fluxes with the published, measured values obtained by the ASPERA instrument carried by Mars Express.

  7. Microphysical, Macrophysical and Radiative Signatures of Volcanic Aerosols in Trade Wind Cumulus Observed by the A-Train

    Science.gov (United States)

    Yuan, T.; Remer, L. A.; Yu, H.

    2011-01-01

    Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-tem1 degassing of a low-lying volcano and use of A-Train satellite observations, we show modifications of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount are associated with volcanic aerosols. In addition we find significantly higher cloud tops for polluted clouds. We demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcin", resulting from direct and indirect forcings including both cloud albedo and cloud amount. is almost an order of magnitude higher than aerosol direct forcing alone. Furthermore, the precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange and trade wind boundary layer. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.

  8. Microphysical, macrophysical and radiative signatures of volcanic aerosols in trade wind cumulus observed by the A-Train

    Directory of Open Access Journals (Sweden)

    T. Yuan

    2011-07-01

    Full Text Available Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-term degassing of a low-lying volcano and use of A-Train satellite observations, we show modifications of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount are associated with volcanic aerosols. In addition we find significantly higher cloud tops for polluted clouds. We demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcin", resulting from direct and indirect forcings including both cloud albedo and cloud amount, is almost an order of magnitude higher than aerosol direct forcing alone. Furthermore, the precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange and trade wind boundary layer. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.

  9. Monothéismes et cinéma

    Directory of Open Access Journals (Sweden)

    Dominique Avon

    2012-06-01

    Full Text Available Monothéismes et cinéma sont deux termes qui ne sont pas couramment unis dans le champ des sciences humaines. Les uns mettent l’accent sur les conflits relatifs à ce qui est permis ou interdit dans les traditions religieuses, les autres soulignent le succès de films promus par des autorités religieuses. La problématique de ce numéro spécial est différente. Le fait est que le cinéma s’est développé principalement hors de l’influence des institutions religieuses. C’est donc à travers des critiques, des groupes de pressions, des sociétés, des magazines et des festivals, plus que par l’intermédiaire de réalisateurs ou d’acteurs, que chrétiens, juifs et –postérieurement- musulmans ont pris part à cette aventure moderne.“Monotheisms” and “cinema” are two words not commonly connected by a link in the field of the human sciences. On one side some people put the stress on conflicts about what is permitted and what is forbidden by religious traditions, on the other side other people underline success of films supported by religious authorities. The issue of this special topic is different. The fact is that cinema grew up mainly out of the influence of religious institutions. So, that is through lobbies, companies, magazines and special festivals more than through film directors or actors that Christians, Jews and –in a later time- Muslims as such have taken part to this modern adventure.

  10. The Interaction Between Two Small Mountainous River Plumes Under Downwelling Wind Conditions in an Idealized Coastal Ocean Model

    Science.gov (United States)

    Lemagie, E. P.; Lerczak, J. A.

    2016-02-01

    Small mountainous rivers are globally significant sources of sediment and nutrients in the coastal ocean. During downwelling wind conditions the combined plumes have been observed to form a buoyant coastal jet which can have an along-shore spatial coherence spanning hundreds of kilometers. This indicates the potential for one-way transport of suspended particulate from a specific river over long distances. Several studies have investigated the dynamics of buoyant coastal currents from combined river sources to understand the influences of wind and river flow. Using an idealized three-dimensional ROMS model, the impact of the interactions between two river plumes on the spatial scales and transport pathways is studied under a constant downwelling wind stress. The model is run for one- and two-river plume scenarios with a range of steady river flow rates. The coastal current is defined by a threshold salinity; to distinguish the contribution from individual rivers, they are each dyed with a unique passive numerical tracer. During downwelling favorable wind conditions the model results indicate a northward flowing buoyant coastal current with bulge regions near the river mouths that vary in size with river flow. Water from the southern river is deflected offshore by the northern bulge, indicating the possibility of a longer residence time in this region. The net transport downstream is relatively unaffected by the presence of the second river, but the shape of the coastal current changes when the buoyancy sources are distributed along the coastline. Under some conditions, there is evidence that water sourced from the southern river can also intrude into the river located to the north. These results further our understanding of the coastal current associated with small, distributed river plumes and the transport pathways of water properties, suspended nutrients, and larvae sourced from individual rivers in these coastal systems such as along the Oregon coast.

  11. DOE handbook: Integrated safety management systems (ISMS) verification team leader`s handbook

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-06-01

    The primary purpose of this handbook is to provide guidance to the ISMS verification Team Leader and the verification team in conducting ISMS verifications. The handbook describes methods and approaches for the review of the ISMS documentation (Phase I) and ISMS implementation (Phase II) and provides information useful to the Team Leader in preparing the review plan, selecting and training the team, coordinating the conduct of the verification, and documenting the results. The process and techniques described are based on the results of several pilot ISMS verifications that have been conducted across the DOE complex. A secondary purpose of this handbook is to provide information useful in developing DOE personnel to conduct these reviews. Specifically, this handbook describes methods and approaches to: (1) Develop the scope of the Phase 1 and Phase 2 review processes to be consistent with the history, hazards, and complexity of the site, facility, or activity; (2) Develop procedures for the conduct of the Phase 1 review, validating that the ISMS documentation satisfies the DEAR clause as amplified in DOE Policies 450.4, 450.5, 450.6 and associated guidance and that DOE can effectively execute responsibilities as described in the Functions, Responsibilities, and Authorities Manual (FRAM); (3) Develop procedures for the conduct of the Phase 2 review, validating that the description approved by the Approval Authority, following or concurrent with the Phase 1 review, has been implemented; and (4) Describe a methodology by which the DOE ISMS verification teams will be advised, trained, and/or mentored to conduct subsequent ISMS verifications. The handbook provides proven methods and approaches for verifying that commitments related to the DEAR, the FRAM, and associated amplifying guidance are in place and implemented in nuclear and high risk facilities. This handbook also contains useful guidance to line managers when preparing for a review of ISMS for radiological

  12. Cloud Computing

    Indian Academy of Sciences (India)

    Cloud computing; services on a cloud; cloud types; computing utility; risks in using cloud computing. Author Affiliations. V Rajaraman1. Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore 560 012, India. Resonance – Journal of Science Education. Current Issue : Vol. 22, Issue 11. Current ...

  13. Characterizing star formation activity in infrared dark cloud MSXDC G048.65-00.29

    NARCIS (Netherlands)

    van der Wiel, M. H. D.; Shipman, R. F.

    2008-01-01

    Context. Infrared dark clouds (IRDCs), condensed regions of the ISM with high column densities, low temperatures and high masses, are suspected sites of star formation. Thousands of IRDCs have already been identified. To date, it has not been resolved whether IRDCs always show star formation

  14. High speed video shooting with continuous-wave laser illumination in laboratory modeling of wind - wave interaction

    Science.gov (United States)

    Kandaurov, Alexander; Troitskaya, Yuliya; Caulliez, Guillemette; Sergeev, Daniil; Vdovin, Maxim

    2014-05-01

    Three examples of usage of high-speed video filming in investigation of wind-wave interaction in laboratory conditions is described. Experiments were carried out at the Wind - wave stratified flume of IAP RAS (length 10 m, cross section of air channel 0.4 x 0.4 m, wind velocity up to 24 m/s) and at the Large Air-Sea Interaction Facility (LASIF) - MIO/Luminy (length 40 m, cross section of air channel 3.2 x 1.6 m, wind velocity up to 10 m/s). A combination of PIV-measurements, optical measurements of water surface form and wave gages were used for detailed investigation of the characteristics of the wind flow over the water surface. The modified PIV-method is based on the use of continuous-wave (CW) laser illumination of the airflow seeded by particles and high-speed video. During the experiments on the Wind - wave stratified flume of IAP RAS Green (532 nm) CW laser with 1.5 Wt output power was used as a source for light sheet. High speed digital camera Videosprint (VS-Fast) was used for taking visualized air flow images with the frame rate 2000 Hz. Velocity air flow field was retrieved by PIV images processing with adaptive cross-correlation method on the curvilinear grid following surface wave profile. The mean wind velocity profiles were retrieved using conditional in phase averaging like in [1]. In the experiments on the LASIF more powerful Argon laser (4 Wt, CW) was used as well as high-speed camera with higher sensitivity and resolution: Optronics Camrecord CR3000x2, frame rate 3571 Hz, frame size 259×1696 px. In both series of experiments spherical 0.02 mm polyamide particles with inertial time 7 ms were used for seeding airflow. New particle seeding system based on utilization of air pressure is capable of injecting 2 g of particles per second for 1.3 - 2.4 s without flow disturbance. Used in LASIF this system provided high particle density on PIV-images. In combination with high-resolution camera it allowed us to obtain momentum fluxes directly from

  15. Storm and cloud dynamics

    CERN Document Server

    Cotton, William R

    1992-01-01

    This book focuses on the dynamics of clouds and of precipitating mesoscale meteorological systems. Clouds and precipitating mesoscale systems represent some of the most important and scientifically exciting weather systems in the world. These are the systems that produce torrential rains, severe winds including downburst and tornadoes, hail, thunder and lightning, and major snow storms. Forecasting such storms represents a major challenge since they are too small to be adequately resolved by conventional observing networks and numerical prediction models.Key Features* Key Highlight

  16. Laboratory Experiments on the Low-temperature Formation of Carbonaceous Grains in the ISM

    Science.gov (United States)

    Fulvio, Daniele; Góbi, Sándor; Jäger, Cornelia; Kereszturi, Ákos; Henning, Thomas

    2017-11-01

    The life cycle of cosmic dust grains is far from being understood and the origin and evolution of interstellar medium (ISM) grains is still under debate. In the ISM, the cosmic dust destruction rate is faster than the production rate by stellar sources. However, observations of ISM refractory matter suggest that to maintain a steady amount of cosmic grains, some supplementary production mechanism takes place. In this context, we aimed to study possible reformation mechanisms of cosmic grains taking place at low temperature directly in the ISM. The low-temperature condensation of carbonaceous materials has been investigated in experiments mimicking the ISM conditions. Gas-phase carbonaceous precursors created by laser ablation of graphite were forced to accrete on cold substrates (T ≈ 10 K) representing surviving dust grains. The growing and evolution of the condensing carbonaceous precursors have been monitored by MIR and UV spectroscopy under a number of experimental scenarios. For the first time, the possibility to form ISM carbonaceous grains in situ is demonstrated. The condensation process is governed by carbon chains that first condense into small carbon clusters and finally into more stable carbonaceous materials, of which structural characteristics are comparable to the material formed in gas-phase condensation experiments at very high temperature. We also show that the so-formed fullerene-like carbonaceous material is transformed into a more ordered material under VUV processing. The cold condensation mechanisms discussed here can give fundamental clues to fully understand the balance between the timescale for dust injection, destruction, and reformation in the ISM.

  17. A neural network Dst index model driven by input time histories of the solar wind-magnetosphere interaction

    Science.gov (United States)

    Revallo, M.; Valach, F.; Hejda, P.; Bochníček, J.

    2014-04-01

    A model to forecast 1-hour lead Dst index is proposed. Our approach is based on artificial neural networks (ANN) combined with an analytical model of the solar wind-magnetosphere interaction. Previously, the hourly solar wind parameters have been considered in the analytical model, all of them provided by registration of the ACE satellite. They were the solar wind magnetic field component Bz, velocity V, particle density n and temperature T. The solar wind parameters have been used to compute analytically the discontinuity in magnetic field across the magnetopause, denoted as [Bt]. This quantity has been shown to be important in connection with ground magnetic field variations. The method was published, in which the weighted sum of a sequence of [Bt] was proposed to produce the value of Dst index. The maximum term in the sum, possessing the maximum weight, is the one denoting the contribution of the current state of the near-Earth solar wind. The role of the older states is less important - the weights exponentially decay. Moreover, the terms turn to zero if Bz⪯0. In this study, we set up a more comprehensive model on the basis of the ANNs. The model is driven by input time histories of the discontinuity in magnetic field [Bt], which are provided by the analytical model. At the output of such revised model, the Dst index is obtained and compared with the real data records. In this way we replaced those exponential weights in the published method with another set of weights determined by the neural networks. We retrospectively tested our models with real data from solar cycle 23. The ANN approach provided better results than a simple method based on exponentially decaying weights. Moreover, we have shown that our ANN model could be used to predict Dst 1 h ahead. We assessed the predictive capability of the model with a set of independent events and found correlation coefficient CC=0.74±0.13 and prediction efficiency PE=0.44±0.15. We also compared our model with

  18. A Standardized Based Approach to Managing Atmosphere Studies For Wind Energy Research

    Science.gov (United States)

    Stephan, E.; Sivaraman, C.

    2015-12-01

    Atmosphere to Electrons (A2e) is a multi-year U.S. Department of Energy (DOE) research initiative targeting significant reductions in the cost of wind energy through an improved understanding of the complex physics governing wind flow into and through wind farms. Better insight into the flow physics has the potential to reduce wind farm energy losses by up to 20%, to reduce annual operational costs by hundreds of millions of dollars, and to improve project financing terms to more closely resemble traditional capital projects. The Data Archive and Portal (DAP) is a key capability of the A2e initiative. The DAP is a cloud-based distributed system known as the 'Wind Cloud' that functions as a repository for all A2e data. This data includes numerous historic and on-going field studies involving in situ and remote sensing instruments, simulations, and scientific analysis. Significantly it is the integration and sharing of these diverse data sets through the DAP that is key to meeting the goals of A2e. This cloud will be accessible via an open and easy-to navigate user interface that facilitates community data access, interaction, and collaboration. DAP management is working with the community, industry, and international standards bodies to develop standards for wind data and to capture important characteristics of all data in the Wind Cloud. Security will be provided to facilitate storage of proprietary data alongside publicly accessible data in the Wind Cloud, and the capability to generate anonymized data will be provided to facilitate using private data by non-privileged users (when appropriate). Finally, limited computing capabilities will be provided to facilitate co-located data analysis, validation, and generation of derived products in support of A2e science.

  19. Impact of macrozoobenthic bioturbation and wind fluctuation interactions on net methylmercury in freshwater lakes.

    Science.gov (United States)

    Wang, Peifang; Yao, Yu; Wang, Chao; Hou, Jun; Qian, Jin; Miao, Lingzhan

    2017-11-01

    The methylmercury (MeHg) as the toxic fractions has presented significant threats to biota in freshwater ecosystems. Hg methylation process is demonstrated to be manipulated by biota process (benthic disturbance and algae bloom existence) as well as the abiotic influence (wind fluctuation and illumination intensity) in freshwater ecosystems. However, the mechanisms influencing Hg methylation are still unclear, and the coupled influences of the biotic and abiotic process with the shifts in variation on methylmercury remain unexplored. Accordingly, an annular flume experiment which simulated the freshwater ecosystem, was conducted for 108 days to examine the influences of typical disturbance by chironomid larvae and wind fluctuations on MeHg variation in sediment profiles. The in-situ, passive sampler technique of revealing diffusive gradients in thin films (DGT) encompassed the special resin, based on referenced extraction and coloration-computer imaging densitometry, were employed to obtain labile MeHg, Fe, and S concentrations at high resolution. The results indicate that larval bioturbation during the initial period of the experiment could diminish bioavailable MeHg concentrations and change the diffusion direction of MeHg fluxes. However, this inhibitive effect on MeHg concentrations ceased with larvae eclosion. Compared to bioturbation, wind fluctuation exerted slow but sustained inhibition on MeHg release. Furthermore, the eight parameters (dissolved organic carbon (DOC), DO, labile Fe and S concentrations, pH, sulfate-reducing bacteria (SRB) abundance in sediment, oxidation-reduction potential (ORP) and EC) could explain more of variation in MeHg concentrations which indicated by the canonical correspondence analysis. And these eight parameters manifest higher explanatory power for MeHg distributed in newly formed sediment. More notably, the comparison results of the multiple and simple regression directly demonstrated the DOC was the fundamental and robust

  20. Computationally Efficient Modelling of Dynamic Soil-Structure Interaction of Offshore Wind Turbines on Gravity Footings

    DEFF Research Database (Denmark)

    Damgaard, Mads; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    2014-01-01

    The formulation and quality of a computationally efficient model of offshore wind turbine surface foundations is examined. The aim is to establish a model, workable in the frequency and time domain, that can be applied in aeroelastic codes for fast and reliable evaluation of the dynamic structural...... to wave propagating in the subsoil–even for soil stratifications with low cut-in frequencies. In this regard, utilising discrete second-order models for the physical interpretation of a rational filter puts special demands on the Newmark β-scheme, where the time integration in most cases only provides...

  1. Laboratory modelling of resonant wave-current interaction in the vicinity wind farm masts

    Science.gov (United States)

    Gunnoo, Hans; Abcha, Nizar; Garcia-Hermosa, Maria-Isabel; Ezersky, Alexander

    2015-04-01

    In the nearest future, by 2020, about 4% of electricity in Europe will be supplied by sea stations operating from renewable sources: ocean thermal energy, wave and tidal energy, wind farms. By now the wind stations located in the coastal zone, provide the most part of electricity in different European countries. Meanwhile, effects of wind farms on the environment are not sufficiently studied. We report results of laboratory simulations aimed at investigation of hydrodynamic fields arising in the vicinity of wind farm masts under the action of currents and surface waves. The main attention is paid to modeling the resonance effects when the amplitude of velocity pulsations in the vicinity of the masts under the joint action of currents and harmonic waves demonstrate significant growth. This resonance can lead to an increase in Reynolds stress on the bottom, intensification of sediment transport and sound generation. The experiments are performed in the 17 meters hydrodynamical channel of laboratory Morphodynamique Continentale et Côtière UMR CNRS 6143. Mast are modeled by vertical cylinder placed in a steady flow. Behind the cylinder turbulent Karman vortex street occurs. Results are obtained in interval of Reynolds numbers Re=103 - 104(Re=Ud/v, where U is the velocity of the flow, d is diameter of the cylinder, ν is cinematic viscosity). Harmonic surface waves of small amplitude propagating upstream are excited by computer controlled wave maker. In the absence of surface waves, turbulent Karman street with averaged frequency f is observed. It is revealed experimentally that harmonic surface waves with a frequencies closed to 2f can synchronize vortex shedding and increase the amplitude of velocity fluctuations in the wake of the cylinder. Map of regimes is found on the parameter plane amplitude of the surface wave - wave frequency. In order to distinguish the synchronization regimes, we defined phase of oscillations using the Hilbert transform technique. We

  2. Simulations of Cloud-Radiation Interaction Using Large-Scale Forcing Derived from the CINDY/DYNAMO Northern Sounding Array

    Science.gov (United States)

    Wang, Shuguang; Sobel, Adam H.; Fridlind, Ann; Feng, Zhe; Comstock, Jennifer M.; Minnis, Patrick; Nordeen, Michele L.

    2015-01-01

    The recently completed CINDY/DYNAMO field campaign observed two Madden-Julian oscillation (MJO) events in the equatorial Indian Ocean from October to December 2011. Prior work has indicated that the moist static energy anomalies in these events grew and were sustained to a significant extent by radiative feedbacks. We present here a study of radiative fluxes and clouds in a set of cloud-resolving simulations of these MJO events. The simulations are driven by the large-scale forcing data set derived from the DYNAMO northern sounding array observations, and carried out in a doubly periodic domain using the Weather Research and Forecasting (WRF) model. Simulated cloud properties and radiative fluxes are compared to those derived from the S-PolKa radar and satellite observations. To accommodate the uncertainty in simulated cloud microphysics, a number of single-moment (1M) and double-moment (2M) microphysical schemes in the WRF model are tested. The 1M schemes tend to underestimate radiative flux anomalies in the active phases of the MJO events, while the 2M schemes perform better, but can overestimate radiative flux anomalies. All the tested microphysics schemes exhibit biases in the shapes of the histograms of radiative fluxes and radar reflectivity. Histograms of radiative fluxes and brightness temperature indicate that radiative biases are not evenly distributed; the most significant bias occurs in rainy areas with OLR less than 150 W/ cu sq in the 2M schemes. Analysis of simulated radar reflectivities indicates that this radiative flux uncertainty is closely related to the simulated stratiform cloud coverage. Single-moment schemes underestimate stratiform cloudiness by a factor of 2, whereas 2M schemes simulate much more stratiform cloud.

  3. Model of the saltation transport by Discrete Element Method coupled with wind interaction

    Science.gov (United States)

    Oger, Luc; Valance, Alexandre

    2017-06-01

    We study the Aeolian saltation transport problem by analysing the collision of incident energetic beads with granular packing. We investigate the collision process for the case where the incident bead and those from the packing have identical mechanical properties. We analyse the features of the consecutive collision process. We used a molecular dynamics method known as DEM (soft Discrete Element Method) with 20000 particles (2D). The grains were displayed randomly in a box (250X60). A few incident disks are launched with a constant velocity and angle with high random position to initiate the flow. A wind velocity profile is applied on the flowing zone of the saltation. The velocity profile is obtained by the calculi of the counter-flow due to the local packing fraction induced by the granular flow. We analyse the evolution of the upper surface of the disk packing. In the beginning, the saltation process can be seen as the classical "splash function" in which one bead hits a fully static dense packing. Then, the quasi-fluidized upper layer of the packing creates a completely different behaviour of the "animated splash function". The dilation of the upper surface due to the previous collisions is responsible for a need of less input energy for launching new ejected disks. This phenomenon permits to maintain a constant granular flow with a "small" wind velocity on the surface of the disk bed.

  4. Grid interaction of offshore wind farms. Part 1. Models for dynamic simulation

    Science.gov (United States)

    Morren, Johan; Pierik, Jan T. G.; de Haan, Sjoerd W. H.; Bozelie, Jan

    2005-07-01

    In this contribution, dynamic wind farm models suitable for fast simulation of power systems are presented. While deriving the models, special attention has been paid to increasing the computational speed of the simulation program. An important increase in speed is realized by the use of the well-known dq0 transformation (Park transformation) not only for the generator but also for all other electrical components. The use of the Park transformation is common practice in electrical machine models, but not in the modelling of other electrical components. For single turbines, simulations in the dq0 reference frame are 100 times faster than simulations in the abc reference frame. After a discussion of the Park transformation and its most important properties, it is explained how models in the dq0 reference frame can be obtained. The dq0 models of the most important electrical components are presented. The mechanical and aerodynamic models that are needed for dynamic simulation of wind turbines are discussed briefly. The models are applied in Part 2. Copyright

  5. The Structural Changes of Tropical Cyclones Upon Interaction with Vertical Wind Shear

    Science.gov (United States)

    Ritchie, Elizabeth A.

    2003-01-01

    The Fourth Convection and Moisture Experiment (CAMEX-4) provided a unique opportunity to observe the distributions and document the roles of important atmospheric factors that impact the development of the core asymmetries and core structural changes of tropical cyclones embedded in vertical wind shear. The state-of-the-art instruments flown on the NASA DC-8 and ER-2, in addition to those on the NOAA aircraft, provided a unique set of observations that documented the core structure throughout the depth of the tropical cyclone. These data have been used to conduct a combined observational and modeling study using a state-of-the-art, high- resolution mesoscale model to examine the role of the environmental vertical wind shear in producing tropical cyclone core asymmetries, and the effects on the structure and intensity of tropical cyclones.The scientific objectives of this study were to obtain in situ measurements that would allow documentation of the physical mechanisms that influence the development of the asymmetric convection and its effect on the core structure of the tropical cyclone.

  6. Model of the saltation transport by Discrete Element Method coupled with wind interaction

    Directory of Open Access Journals (Sweden)

    Oger Luc

    2017-01-01

    Full Text Available We study the Aeolian saltation transport problem by analysing the collision of incident energetic beads with granular packing. We investigate the collision process for the case where the incident bead and those from the packing have identical mechanical properties. We analyse the features of the consecutive collision process. We used a molecular dynamics method known as DEM (soft Discrete Element Method with 20000 particles (2D. The grains were displayed randomly in a box (250X60. A few incident disks are launched with a constant velocity and angle with high random position to initiate the flow. A wind velocity profile is applied on the flowing zone of the saltation. The velocity profile is obtained by the calculi of the counter-flow due to the local packing fraction induced by the granular flow. We analyse the evolution of the upper surface of the disk packing. In the beginning, the saltation process can be seen as the classical “splash function” in which one bead hits a fully static dense packing. Then, the quasi-fluidized upper layer of the packing creates a completely different behaviour of the “animated splash function”. The dilation of the upper surface due to the previous collisions is responsible for a need of less input energy for launching new ejected disks. This phenomenon permits to maintain a constant granular flow with a “small” wind velocity on the surface of the disk bed.

  7. SHAPE Project Vortex Bladeless: Parallel multi-code coupling for Fluid-Structure Interaction in Wind Energy Generation

    OpenAIRE

    J.C. Cajas

    2016-01-01

    Vortex-Bladeless is a Spanish SME whose objective is to develop a new concept of wind turbine without blades called Vortex or vorticity wind turbine. This design represents a new paradigm in wind energy and aims to eliminate or reduce many of the existing problems in conventional generators. Due to the significant difference in the project concept, its scope is different from conventional wind turbines. It is particularly suitable for offshore configuration and it could be exploited in wind f...

  8. Plume and Shock Interaction Effects on Sonic Boom in the 1-foot by 1-foot Supersonic Wind Tunnel

    Science.gov (United States)

    Castner, Raymond; Elmiligui, Alaa; Cliff, Susan; Winski, Courtney

    2015-01-01

    The desire to reduce or eliminate the operational restrictions of supersonic aircraft over populated areas has led to extensive research at NASA. Restrictions are due to the disturbance of the sonic boom, caused by the coalescence of shock waves formed by the aircraft. A study has been performed focused on reducing the magnitude of the sonic boom N-wave generated by airplane components with a focus on shock waves caused by the exhaust nozzle plume. Testing was completed in the 1-foot by 1-foot supersonic wind tunnel to study the effects of an exhaust nozzle plume and shock wave interaction. The plume and shock interaction study was developed to collect data for computational fluid dynamics (CFD) validation of a nozzle plume passing through the shock generated from the wing or tail of a supersonic vehicle. The wing or tail was simulated with a wedgeshaped shock generator. This test entry was the first of two phases to collect schlieren images and off-body static pressure profiles. Three wedge configurations were tested consisting of strut-mounted wedges of 2.5- degrees and 5-degrees. Three propulsion configurations were tested simulating the propulsion pod and aft deck from a low boom vehicle concept, which also provided a trailing edge shock and plume interaction. Findings include how the interaction of the jet plume caused a thickening of the shock generated by the wedge (or aft deck) and demonstrate how the shock location moved with increasing nozzle pressure ratio.

  9. A Ten-Year Global Record of Absorbing Aerosols Above Clouds from OMI's Near-UV Observations

    Science.gov (United States)

    Jethva, Hiren; Torres, Omar; Ahn, Changwoo

    2016-01-01

    Aerosol-cloud interaction continues to be one of the leading uncertain components of climate models, primarily due to the lack of an adequate knowledge of the complex microphysical and radiative processes associated with the aerosol-cloud system. The situations when aerosols and clouds are found in the same atmospheric column, for instance, when light-absorbing aerosols such as biomass burning generated carbonaceous particles or wind-blown dust overlay low-level cloud decks, are commonly found over several regional of the world. Contrary to the cloud-free scenario over dark surface, for which aerosols are known to produce a net cooling effect (negative radiative forcing) on climate, the overlapping situation of absorbing aerosols over cloud can potentially exert a significant level of atmospheric absorption and produces a positive radiative forcing at top-of-atmosphere. The magnitude of direct radiative effects of aerosols above cloud depends directly on the aerosol loading, microphysical-optical properties of the aerosol layer and the underlying cloud deck, and geometric cloud fraction. We help in addressing this problem by introducing a novel product of optical depth of absorbing aerosols above clouds retrieved from near-UV observations made by the Ozone Monitoring Instrument (OMI) on board NASA's Aura platform. The presence of absorbing aerosols above cloud reduces the upwelling radiation reflected by cloud and produces a strong 'color ratio' effect in the near-UV region, which can be unambiguously detected in the OMI measurements. Physically based on this effect, the OMACA algorithm retrieves the optical depths of aerosols and clouds simultaneously under a prescribed state of atmosphere. The algorithm architecture and results from a ten-year global record including global climatology of frequency of occurrence and above-cloud aerosol optical depth, and a discussion on related future field campaigns are presented.

  10. A Global, Decadal, Quantitative Record of Absorbing Aerosols above Cloud Using OMI's Near-UV Observations

    Science.gov (United States)

    Torres, O.; Jethva, H. T.; Ahn, C.

    2016-12-01

    Aerosol-cloud interaction continues to be one of the leading uncertain components of climate models, primarily due to the lack of an adequate knowledge of the complex microphysical and radiative processes of the aerosol-cloud system. The situations when aerosols and clouds are found in the same atmospheric column, for instance, when light-absorbing aerosols such as biomass burning generated carbonaceous particles or wind-blown dust overlay low-level cloud decks, are commonly found over several regions of the world. Contrary to the known cooling effects of these aerosols in cloud-free scenario over dark surface, the overlapping situation of absorbing aerosols over cloud can potentially exert a significant level of atmospheric absorption and produces a positive radiative forcing (warming) at top-of-atmosphere. The magnitude of direct radiative effects of aerosols above cloud directly depends on the aerosol loading, microphysical and optical properties of the aerosol layer and the underlying cloud deck, and geometric cloud fraction. We help in addressing this problem by introducing a novel product of above-cloud aerosol optical depth (ACAOD) of absorbing aerosols retrieved from near-UV observations made by the Ozone Monitoring Instrument (OMI) on board NASA's Aura platform. Physically based on the strong `color ratio' effect in the near-UV caused by the spectral absorption of aerosols above cloud, the algorithm, formally named as OMACA, retrieves the optical depths of aerosols and clouds simultaneously under a prescribed state of atmosphere. Here, we present the algorithm architecture and results from an 11-year global record (2005-2015) including global climatology of frequency of occurrence and ACAOD. The theoretical uncertainty analysis and planned validation activities using measurements from upcoming field campaigns are also discussed.

  11. Shocks in Dense Clouds in the Vela Supernova Remnant: FUSE

    Science.gov (United States)

    Nichols, Joy; Sonneborn, George (Technical Monitor)

    2002-01-01

    We have obtained 8 LWRS FUSE spectra to study a recently identified interaction of the Vela supernova remnant with a dense cloud region along its western edge. The goal is to quantify the temperature, ionization, density, and abundance characteristics associated with this shock/dense cloud interface by means of UV absorption line studies. Our detection of high-velocity absorption line C I at +90 to +130 km/s with IUE toward a narrow region interior to the Vela SNR strongly suggests the Vela supernova remnant is interacting with a dense ISM or molecular cloud. The shock/dense cloud interface is suggested by (1) the rarity of detection of high-velocity C I seen in IUE spectra, (2) its very limited spatial distribution in the remnant, and (3) a marked decrease in X-ray emission in the region immediately west of the position of these stars where one also finds a 100 micron emission ridge in IRAS images. We have investigated the shock physics and general properties of this interaction region through a focussed UV absorption line study using FUSE spectra. We have FUSE data on OVI absorption lines observed toward 8 stars behind the Vela supernova remnant (SNR). We compare the OVI observations with IUE observations of CIV absorption toward the same stars. Most of the stars, which are all B stars, have complex continua making the extraction of absorption lines difficult. Three of the stars, HD 72088, HD 72089 and HD 72350, however, are rapid rotators (v sin i less than 100 km/s) making the derivation of absorption column densities much easier. We have measured OVI and CIV column densities for the "main component" (i.e. the low velocity component) for these stars. In addition, by removing the H2 line at 1032.35A (121.6 km/s relative to OVI), we find high velocity components of OVI at approximately 150 km/s that we attribute to the shock in the Vela SNR. The column density ratios and magnitudes are compared to both steady shock models and results of hydrodynamical SNR

  12. Exploring interactions between payment for hydrologic service policies, landowner decisions, and ecohydrology in a Mexican cloud forest watershed: Is there a disconnect between the policy and the resource?

    Science.gov (United States)

    Asbjornsen, H.; Geissert, D.; Gomez-Tagle, A.; Holwerda, F.; Manson, R.; Perez-Maqueo, O.; Munoz-Villers, L.; Scullion, J.

    2013-05-01

    Payment for hydrologic service (PHS) programs are increasingly being used as a means to incentivize watershed protection by compensating upstream 'water producers' with payments made by downstream 'water consumers'. However, the effectiveness of PHS programs in achieving their target goals is often poorly understood. Here, we draw from insights obtained from socioeconomic and ecohydrological research in Veracruz, Mexico to explore interactions between PHS policies, landowner decisions, and hydrologic services. GIS analysis of land-cover changes during 2003-2009 combined with interviews of PHS participants indicated that despite lower deforestation rates on properties receiving PES payments, other factors were likely to have a greater influence on land use decisions than PHS payments per se, including opportunity costs and personal conservation ethic. The interviews also highlighted a general lack of trust and cooperation between the citizen participants and government administrators, which was reflected in the relatively low level of knowledge of the PHS programs' regulations and goals, the role of forests in protecting water resources, and a low level of co-financing by the private sector. An important premise of PHS programs is that protecting existing forest cover (and planting trees) will enhance water supply, especially in upland cloud forests that are due to their perceived role as water producers. Measurements of climate, steamflow, canopy fog interception, plant transpiration, soil water dynamics, and hydrologic flow paths were collected over a 3-year period to assess stand water balance and streamflow response under four different land covers: mature cloud forest, pasture, regenerating cloud forest, pine reforestation. Results suggested relatively minor additional inputs of fog to increasing streamflow in cloud forest watersheds, while conversion of forest to pasture did not markedly decrease dry season flows, but did increase annual flows due to lower

  13. Evolving MCDM Applications Using Hybrid Expert-Based ISM and DEMATEL Models: An Example of Sustainable Ecotourism

    Directory of Open Access Journals (Sweden)

    Huan-Ming Chuang

    2013-01-01

    Full Text Available Ecological degradation is an escalating global threat. Increasingly, people are expressing awareness and priority for concerns about environmental problems surrounding them. Environmental protection issues are highlighted. An appropriate information technology tool, the growing popular social network system (virtual community, VC, facilitates public education and engagement with applications for existent problems effectively. Particularly, the exploration of related involvement behavior of VC member engagement is an interesting topic. Nevertheless, member engagement processes comprise interrelated sub-processes that reflect an interactive experience within VCs as well as the value co-creation model. To address the top-focused ecotourism VCs, this study presents an application of a hybrid expert-based ISM model and DEMATEL model based on multi-criteria decision making tools to investigate the complex multidimensional and dynamic nature of member engagement. Our research findings provide insightful managerial implications and suggest that the viral marketing of ecotourism protection is concerned with practitioners and academicians alike.

  14. Evolving MCDM applications using hybrid expert-based ISM and DEMATEL models: an example of sustainable ecotourism.

    Science.gov (United States)

    Chuang, Huan-Ming; Lin, Chien-Ku; Chen, Da-Ren; Chen, You-Shyang

    2013-01-01

    Ecological degradation is an escalating global threat. Increasingly, people are expressing awareness and priority for concerns about environmental problems surrounding them. Environmental protection issues are highlighted. An appropriate information technology tool, the growing popular social network system (virtual community, VC), facilitates public education and engagement with applications for existent problems effectively. Particularly, the exploration of related involvement behavior of VC member engagement is an interesting topic. Nevertheless, member engagement processes comprise interrelated sub-processes that reflect an interactive experience within VCs as well as the value co-creation model. To address the top-focused ecotourism VCs, this study presents an application of a hybrid expert-based ISM model and DEMATEL model based on multi-criteria decision making tools to investigate the complex multidimensional and dynamic nature of member engagement. Our research findings provide insightful managerial implications and suggest that the viral marketing of ecotourism protection is concerned with practitioners and academicians alike.

  15. How does increasing horizontal resolution in a global climate model improve the simulation of aerosol-cloud interactions?: RESOLUTION DEPENDENCE OF AIF

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Po-Lun [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Rasch, Philip J. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Wang, Minghuai [Institute for Climate and Global Change Research and School of Atmospheric Sciences, Nanjing University, Nanjing China; Jiangsu Collaborative Innovation Center of Climate Change, Nanjing China; Wang, Hailong [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Ghan, Steven J. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Easter, Richard C. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Gustafson, William I. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Liu, Xiaohong [Department of Atmospheric Science, University of Wyoming, Laramie Wyoming USA; Zhang, Yuying [Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore California USA; Ma, Hsi-Yen [Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore California USA

    2015-06-23

    The Community Atmosphere Model Version 5 is run at horizontal grid spacing of 2, 1, 0.5, and 0.25°, with the meteorology nudged toward the Year Of Tropical Convection analysis, and cloud simulators and the collocated A-Train satellite observations are used to explore the resolution dependence of aerosol-cloud interactions. The higher-resolution model produces results that agree better with observations, showing an increase of susceptibility of cloud droplet size, indicating a stronger first aerosol indirect forcing (AIF), and a decrease of susceptibility of precipitation probability, suggesting a weaker second AIF. The resolution sensitivities of AIF are attributed to those of droplet nucleation and precipitation parameterizations. The annual average AIF in the Northern Hemisphere midlatitudes (where most anthropogenic emissions occur) in the 0.25° model is reduced by about 1 W m-2 (-30%) compared to the 2° model, leading to a 0.26 W m-2 reduction (-15%) in the global annual average AIF.

  16. Three-dimensional, multifluid, high spatial resolution MHD model studies of the solar wind interaction with Mars

    Science.gov (United States)

    Najib, Dalal; Nagy, Andrew F.; Tóth, Gábor; Ma, Yingjuan

    2011-05-01

    Our newly developed 3-D, multifluid MHD model is used to study the interaction of the solar wind with Mars. This model is based on the BATS-R-US code, using a spherical grid and a radial resolution equ