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Sample records for 3d solar wind

  1. Coronal roots of solar wind streams: 3-D MHD modeling

    NASA Technical Reports Server (NTRS)

    Pisanko, Yu. V.

    1995-01-01

    Weak (discontinuous) solutions of the 3-D MHD equations look like a promising tool to model the transonic solar wind with structural elements: current sheets, coronal plumes etc. Using the observational information about various coronal emissions one can include these structural elements into the 3-D MHD solar wind model by embedding the discontinuities of given type. Such 3-D MHD structured solar wind is calculated self-consistently: variants are examined via numerical experiments. In particular, the behavior of coronal plumes in the transonic solar wind flow, is modeled. The input information for numerical modeling (for example, the magnetic field map at the very base of the solar corona) can be adjusted so that fast stream arises over the center of the coronal hole, over the coronal hole boundaries and, even, over the region with closed magnetic topology. 3-D MHD equations have the analytical solution which can serve as a model of supersonic trans-alfvenic solar wind in the (5-20) solar radii heliocentric distance interval. The transverse, nonradial total (gas + magnetic field) pressure balance in the flow is the corner-stone of this solution. The solution describes the filamentation (ray-like structure of the solar corona) and streaming (formation of high-speed streams with velocities up to 800 km/sec) as a consequence of the magnetic field spatial inhomogeneous structure and trans-alfvenic character of the flow. The magnetic field works in the model as a 'controller' for the solar wind streaming and filamentation.

  2. 3D Simulations of Helmet Streamer Dynamics and Implications for the Slow Solar Wind

    NASA Astrophysics Data System (ADS)

    Higginson, Aleida K.; Antiochos, Spiro K.; DeVore, C. R.; Zurbuchen, Thomas H.

    2015-04-01

    The source of the slow solar wind at the Sun is still an issue of intense debate in solar and heliospheric physics. Because the majority of the solar wind observed at Earth is slow wind, understanding its origin is essential for understanding and predicting Earth’s space weather environment. In-situ and remote observations show that, when compared to the fast wind, the slow solar wind corresponds to higher freeze-in temperatures, as indicated by charge-state ratios, and more corona-like elemental abundance ratios. These results indicate that the most likely source for the slow wind is the hot plasma in the closed-field corona, but the release mechanism(s) for the wind from the closed-field regions is far from understood. We perform fully dynamic, 3D MHD simulations in order to the study the opening and closing of the Sun’s magnetic field that leads to the escape of the slow solar wind. In particular, we calculate the dynamics of helmet streamers that are driven by photospheric motions such as supergranular flows. We determine in detail the opening and closing of coronal flux, and discuss the implications of our results for theories of slow wind origin, especially the S-Web model. We also determine observational signatures for the upcoming inner heliosphere missions Solar Orbiter and Solar Probe Plus.This work was supported by the NASA SR&T and TR&T Programs.

  3. 3D Solar Wind Structure Features Characterizing the Rise of Cycle 24

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Ellenburg, M. A.; Riley, P.; Lee, C. O.; Arge, C. N.; Jian, L.; Russell, C. T.; Simunac, K.; Galvin, A. B.; Petrie, G. J.

    2011-12-01

    Since the launch of the STEREO mission in 2006, there has been renewed interest in the 3D structure of the solar wind, spurred in part by the unusual cycle 23 solar minimum and current solar cycle rise. Of particular significance for this subject has been the ubiquitous occurrence of low latitude coronal holes and coronal pseudo-streamers. These coupled features have been common both because of the relative strength of high order spherical harmonic content of the global coronal field, and the weakness of the field compared to the previous two well-observed cycles. We consider the effects of the low latitude coronal holes and pseudo-streamers on the near-ecliptic solar wind and interplanetary field. In particular, we illustrate how the now common passage of streams with low latitude sources and pseudo-streamer boundaries is changing our traditional perceptions of local solar wind structures.

  4. A global 3-D MHD model of the solar wind with Alfven waves

    NASA Technical Reports Server (NTRS)

    Usmanov, A. V.

    1995-01-01

    A fully three-dimensional solar wind model that incorporates momentum and heat addition from Alfven waves is developed. The proposed model upgrades the previous one by considering self-consistently the total system consisting of Alfven waves propagating outward from the Sun and the mean polytropic solar wind flow. The simulation region extends from the coronal base (1 R(sub s) out to beyond 1 AU. The fully 3-D MHD equations written in spherical coordinates are solved in the frame of reference corotating with the Sun. At the inner boundary, the photospheric magnetic field observations are taken as boundary condition and wave energy influx is prescribed to be proportional to the magnetic field strength. The results of the model application for several time intervals are presented.

  5. The 3-D solar radioastronomy and the structure of the corona and the solar wind. [solar probes of solar activity

    NASA Technical Reports Server (NTRS)

    Steinberg, J. L.; Caroubalos, C.

    1976-01-01

    The mechanism causing solar radio bursts (1 and 111) is examined. It is proposed that a nonthermal energy source is responsible for the bursts; nonthermal energy is converted into electromagnetic energy. The advantages are examined for an out-of-the-ecliptic solar probe mission, which is proposed as a means of stereoscopically viewing solar radio bursts, solar magnetic fields, coronal structure, and the solar wind.

  6. Age Dependence of Wind Properties for Solar-type Stars: A 3D Study

    NASA Astrophysics Data System (ADS)

    Réville, Victor; Folsom, Colin P.; Strugarek, Antoine; Brun, Allan Sacha

    2016-12-01

    Young and rapidly rotating stars are known for intense, dynamo-generated magnetic fields. Spectropolarimetric observations of those stars in precisely aged clusters are key input for gyrochronology and magnetochronology. We use Zeeman Doppler imaging maps of several young K-type stars of similar mass and radius but with various ages and rotational periods to perform three-dimensional (3D) numerical MHD simulations of their coronae and follow the evolution of their magnetic properties with age. Those simulations yield the coronal structure as well as the instant torque exerted by the magnetized, rotating wind on the star. As stars get older, we find that the angular momentum loss decreases with {{{Ω }}}\\star 3, which is the reason for the convergence on the Skumanich law. For the youngest stars of our sample, the angular momentum loss shows signs of saturation around 8{{{Ω }}}⊙ , which is a common value used in spin evolution models for K-type stars. We compare these results to semianalytical models and existing braking laws. We observe a complex wind-speed distribution for the youngest stars with slow, intermediate, and fast wind components, which are the result of interaction with intense and nonaxisymmetric magnetic fields. Consequently, in our simulations, the stellar wind structure in the equatorial plane of young stars varies significantly from a solar configuration, delivering insight about the past of the solar system interplanetary medium.

  7. Sensitivity of the Earth Magnetosphere to the Solar Wind Activity: 3D Macroparticle Model

    NASA Astrophysics Data System (ADS)

    Baraka, S. M.; Ben Jaffel, L.

    2006-05-01

    A new approach is proposed to study the sensitivity of the Earth Magnetosphere to the variability of the Solar Wind bulk velocity. A numerical particles in cell (PIC) method initially proposed by Buneman (1993) has been adopted and modified to carry out the study. Space was stretched as cubic boxes of dimension 155x105x105 Re filled with 2 million of Solar Wind particles, with Earth is located at 60x52x53 Re. The magnetic field of Earth was hypothetically set to zero, and then switched on. The formation of the magnetospheric cavity and its elongation around the planet was observed to evolve with time until a steady state topology of the system is attained with the classical structure of a magnetosphere. We also found that the cavity is repopulated by clouds of particles from the Solar Wind, producing the current sheet-- a thin plasma sheet that stands at the equatorial plane. The study was carried out with the very basic elements of the interaction processes as described by Maxwell and Lorentz equations. IMF was then included as a steady southward magnetic field. Drift velocity of the Solar Wind was changed to simulate compression/depression of the system. 3-D analysis of the response of the magnetosphere dayside to that variation was studied, and the corresponding relaxation time of the magnetopause interface was measured. In response to the Solar Wind drift velocity imposed drop-off, a ~ 15 Re gap in the incoming Solar Wind plasma appeared moving toward Earth. As soon as the gap hit the initial shock of the steady magnetosphere, a reconnection between the Earth magnetic field and IMF was noticed at the dayside magnetopause when IMF was included. Injection of nightside of the magnetosphere by energetic particles due to magnetic erosion and reconnection is observed. During the expansion phase of the disturbance, the outer boundary of the dayside magnetopause broke up during the absence of the IMF as it responded to the reduction of the ram pressure, whilst

  8. Three-fluid, 3D MHD solar wind modeling with turbulence transport and eddy viscosity

    NASA Astrophysics Data System (ADS)

    Usmanov, A. V.; Goldstein, M. L.; Matthaeus, W. H.

    2014-12-01

    We present results from a three-fluid, fully three-dimensional MHD solar wind model that includes turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating. The solar wind plasma is described as a co-moving system of three species: the solar wind protons, electrons, and interstellar pickup protons. Separate energy equations are employed for each species. We obtain numerical solutions of Reynolds-averaged solar wind equations coupled with turbulence transport equations in the region from 0.3 to 100 AU. The integrated system of equations includes the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. Using either a dipole approximation for the solar magnetic field or synoptic solar magnetograms from the Wilcox Solar Observatory for assigning boundary conditions at the coronal base, we apply the model to study the global structure of the solar wind and its three-dimensional properties, including turbulence parameters, throughout the heliosphere. The model results are compared with observations on WIND, Ulysses and Voyager 2 spacecraft. This work is partially supported by LWS and Heliophysics Grand Challenges programs.

  9. Fully Kinetic 3D Simulations of the Interaction of the Solar Wind with Mercury

    NASA Astrophysics Data System (ADS)

    Amaya, J.; Deca, J.; Lembege, B.; Lapenta, G.

    2015-12-01

    The planet Mercury has been studied by the space mission Mariner 10, in the 1970's, and by the MESSENGER mission launched in 2004. Interest in the first planet of the Solar System has now been renewed by the launch in 2017 of the BepiColombo mission. MESSENGER and BepiColombo give access to information about the local conditions of the magnetosphere of Mercury. This data must be evaluated in the context of the global interaction between the solar wind and the planet's magnetosphere. Global scale simulations of the planet's environment are necessary to fully understand the data gathered from in-situ measurements. We use three-dimensional simulations to support the scientific goals of the two missions. In contrast with the results based on MHD (Kabin et al., 2000) and hybrid codes (Kallio et Janhumen, 2003; Travnicek et al., 2007, 2010; Richer et al., 2012), the present work is based on the implicit moment Particle-in-Cell (PiC) method, which allows to use large time and space steps, while granting access to the dynamics of the smaller electron scales in the plasma. The purpose of these preliminary PIC simulations is to retrieve the top-level features of Mercury's magnetosphere and its frontiers. We compare the results obtained with the implicit moment PiC method against 3D hybrid simulations. We perform simulations of the global plasma environment of Mercury using the solar wind conditions measured by MESSENGER. We show that complex flows form around the planet, including the development of Kelvin-Helmoltz instabilities at the flanks. We evaluate the dynamics of the shock, magnetosheath, magnetopause, the reconnection areas, the formation of plasma sheet and magnetotail, and the variation of ion/electron plasma flows when crossing these frontiers. The simulations also give access to detailed information about the particle dynamics and their velocity distribution at locations that can be used for comparison with data from MESSENGER and later on with the forthcoming

  10. Modeling solar wind mass-loading in the vicinity of the Sun using 3-D MHD simulations

    NASA Astrophysics Data System (ADS)

    Rasca, A. P.; Horányi, M.; Oran, R.; Holst, B.

    2014-01-01

    Collisionless shocks due to mass-loading were first discussed to describe the solar wind flow around a cometary atmosphere, showing its choking effects on the flow. Recent observations have led to an increased interest in mass-loading occurring in the solar corona due to both sungrazing comets and collisional debris production by sunward migrating interplanetary dust particles. The 1-D simulations with a hydrodynamic model have illustrated the impact on the solar wind from abrupt mass-loading in the coronal region. Full 3-D magnetohydrodynamic (MHD) simulations using a solar corona model based on the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme code provide a more realistic coronal environment for modeling specific events applicable to modeling the mass-loaded coronal wind. A specific application is introduced modeling the mass-loading effects from a sungrazing comet.

  11. 3-D MHD Model of the Solar Wind-Interplanetary Space Combining System 1:Variation of Solar Wind Speed Associated with the Photospheric Magnetic Field

    NASA Astrophysics Data System (ADS)

    Nakamizo, A.; Tanaka, T.

    2006-12-01

    Existing global models of the solar-wind/IMF expanding to the Earth's orbit are basically grounded in the idea of "source surface." It is widely accepted that the sector structure and the solar wind speed are primarily controlled by the magnetic field at the source surface and the so-called "expansion factor." On the other hand, 3-D MHD model is still off from practical use because both of scientific and technical problems. One of the former problems is the reproduction of supersonic solar-wind. From the viewpoint of the physics of the solar wind, coronal heating and outward acceleration mechanisms are invoked to explain the supersonic evolution of the solar wind. Since the mechanism responsible for the heating/acceleration is still one of the primary subjects of the physics of the solar wind, many MHD models have taken into account their effects by incorporating additional source terms corresponding to promising candidates such as thermal conductions, radiation losses and wave pressures. However there are few MHD models considering the effect of the expansion factor, which determines the solar-wind speed in the series of source surface models. In this study we newly incorporate the flux tube expansion rate into the MHD equation system including heat source function in the energy equation. Appling the unstructured grid system, we achieved the dense grid spacing at the inner boundary, which enable us to adopt realistic solar magnetic fields, and a size of simulation space of 1AU. Photospheric magnetic field data is used as the inner boundary condition.The simulation results are summarized as: (1) The variation of solar wind speed is well controlled by the structure of magnetic fields at and little above the solar surface and (2) Far above the solar surface, the interface between high and low speed flows evolves to a structure suggestive of CIRs. Comparing the data from simulation with the actual solar wind data obtained by spacecrafts, we will discuss the future

  12. Electromagnetic 2D/3D Particle-in-Cell simulations of the solar wind interaction with lunar crustal anomalies.

    NASA Astrophysics Data System (ADS)

    Deca, Jan; Lapenta, Giovanni; Lembège, Bertrand; Divin, Andrey; Markidis, Stefano; Amaya, Jorge

    2013-04-01

    We present the first 2D/3D fully kinetic Particle-in-Cell simulations of the solar wind interaction with lunar crustal magnetic anomalies. The simulations are performed using the implicit electromagnetic Particle-in-Cell code iPIC3D [Markidis, Lapenta & Rizwan-uddin, 2010]. Multiscale physics is resolved for all plasma components (heavy ions, protons and electrons) in the code, recently updated with a set of open boundary conditions designed for solar wind-body interactions. We use a dipole to model the crustal anomaly. The dipole center is located outside the computational domain and the boundary representing the lunar surface is modeled as a particle-absorbing plane. Photo-emission from the lunar surface is at this point not included, but will be in future work. We study the behaviour of the dipole model with variable surface magnetic field strength under changing solar wind conditions and confirm that lunar crustal magnetic fields may indeed be strong enough to stand off the solar wind and form a mini-magnetosphere, as suggested by MHD simulations [Harnett & Winglee, 2000, 2002, 2003] and spacecraft observations [Kurata et al., 2005; Halekas et al., 2008; Wieser et al., 2010]. 3D-PIC simulations reveal to be very helpful to analyze the diversion/braking of the particle flux and the characteristics of the resulting particles accumulation. The particle flux to the surface is significantly reduced at the magnetic anomaly, surrounded by a region of enhanced density due to the magnetic mirror effect. Finally we will present preliminary results on the interaction of the solar wind with weaker magnetic anomalies in which highly non-adiabatic interactions are expected.

  13. First Lunar Wake Passage of ARTEMIS: Discrimination of Wake Effects and Solar Wind Fluctuations by 3D Hybrid Simulations

    NASA Technical Reports Server (NTRS)

    Wiehle, S.; Plaschke, F.; Motschmann, U.; Glassmeier, K. H.; Auster, H. U.; Angelopoulos, V.; Mueller, J.; Kriegel, H.; Georgescu, E.; Halekas, J.; Sibeck, D. G.; McFadden, J. P.

    2011-01-01

    The spacecraft P1 of the new ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) mission passed the lunar wake for the first time on February 13, 2010. We present magnetic field and plasma data of this event and results of 3D hybrid simulations. As the solar wind magnetic field was highly dynamic during the passage, a simulation with stationary solar wind input cannot distinguish whether distortions were caused by these solar wind variations or by the lunar wake; therefore, a dynamic real-time simulation of the flyby has been performed. The input values of this simulation are taken from NASA OMNI data and adapted to the P1 data, resulting in a good agreement between simulation and measurements. Combined with the stationary simulation showing non-transient lunar wake structures, a separation of solar wind and wake effects is achieved. An anisotropy in the magnitude of the plasma bulk flow velocity caused by a non-vanishing magnetic field component parallel to the solar wind flow and perturbations created by counterstreaming ions in the lunar wake are observed in data and simulations. The simulations help to interpret the data granting us the opportunity to examine the entire lunar plasma environment and, thus, extending the possibilities of measurements alone: A comparison of a simulation cross section to theoretical predictions of MHD wave propagation shows that all three basic MHD modes are present in the lunar wake and that their expansion governs the lunar wake refilling process.

  14. 3D ELECTRON DENSITY DISTRIBUTIONS IN THE SOLAR CORONA DURING SOLAR MINIMA: ASSESSMENT FOR MORE REALISTIC SOLAR WIND MODELING

    SciTech Connect

    Patoul, Judith de; Foullon, Claire; Riley, Pete E-mail: c.foullon@exeter.ac.uk

    2015-11-20

    Knowledge of the electron density distribution in the solar corona put constraints on the magnetic field configurations for coronal modeling and on initial conditions for solar wind modeling. We work with polarized SOHO/LASCO-C2 images from the last two recent minima of solar activity (1996–1997 and 2008–2010), devoid of coronal mass ejections. The goals are to derive the 4D electron density distributions in the corona by applying a newly developed time-dependent tomographic reconstruction method and to compare the results between the two solar minima and with two magnetohydrodynamic models. First, we confirm that the values of the density distribution in thermodynamic models are more realistic than in polytropic ones. The tomography provides more accurate distributions in the polar regions, and we find that the density in tomographic and thermodynamic solutions varies with the solar cycle in both polar and equatorial regions. Second, we find that the highest-density structures do not always correspond to the predicted large-scale heliospheric current sheet or its helmet streamer but can follow the locations of pseudo-streamers. We deduce that tomography offers reliable density distributions in the corona, reproducing the slow time evolution of coronal structures, without prior knowledge of the coronal magnetic field over a full rotation. Finally, we suggest that the highest-density structures show a differential rotation well above the surface depending on how they are magnetically connected to the surface. Such valuable information on the rotation of large-scale structures could help to connect the sources of the solar wind to their in situ counterparts in future missions such as Solar Orbiter and Solar Probe Plus.

  15. 3D Electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies

    NASA Astrophysics Data System (ADS)

    Deca, J.; Lapenta, G.; Divin, A. V.; Lembege, B.; Markidis, S.

    2013-12-01

    Unlike the Earth and Mercury, our Moon has no global magnetic field and is therefore not shielded from the impinging solar wind by a magnetosphere. However, lunar magnetic field measurements made by the Apollo missions provided direct evidence that the Moon has regions of small-scale crustal magnetic fields, ranging up to a few 100km in scale size with surface magnetic field strengths up to hundreds of nanoTeslas. More recently, the Lunar Prospector spacecraft has provided high-resolution observations allowing to construct magnetic field maps of the entire Moon, confirming the earlier results from Apollo, but also showing that the lunar plasma environment is much richer than earlier believed. Typically the small-scale magnetic fields are non-dipolar and rather tiny compared to the lunar radius and mainly clustered on the far side of the moon. Using iPic3D we present the first 3D fully kinetic and electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies. We study the behaviour of a dipole model with variable surface magnetic field strength under changing solar wind conditions and confirm that lunar crustal magnetic fields may indeed be strong enough to stand off the solar wind and form a mini-magnetosphere, as suggested by MHD and hybrid simulations and spacecraft observations. 3D-PIC simulations reveal to be very helpful to analyze the diversion/braking of the particle flux and the characteristics of the resulting particles accumulation. The particle flux to the surface is significantly reduced at the magnetic anomaly, surrounded by a region of enhanced density due to the magnetic mirror effect. Second, the ability of iPic3D to resolve all plasma components (heavy ions, protons and electrons) allows to discuss in detail the electron physics leading to the highly non-adiabatic interactions expected as well as the implications for solar wind shielding of the lunar surface, depending on the scale size (solar wind protons

  16. Observations of the 3-D distribution of interplanetary electrons and ions from solar wind plasma to low energy cosmic rays

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Anderson, K. A.; Ashford, S.; Carlson, C.; Curtis, D.; Ergun, R.; Larson, D.; McFadden, J.; McCarthy, M.; Parks, G. K.

    1995-01-01

    The 3-D Plasma and Energetic Particle instrument on the GGS Wind spacecraft (launched November 1, 1994) is designed to make measurements of the full three-dimensional distribution of suprathermal electrons and ions from solar wind plasma to low energy cosmic rays, with high sensitivity, wide dynamic range, good energy and angular resolution, and high time resolution. Three pairs of double-ended telescopes, each with two or three closely sandwiched passivated ion implanted silicon detectors measure electrons and ions from approximately 20 keV to greater than or equal to 300 keV. Four top-hat symmetrical spherical section electrostatic analyzers with microchannel plate detectors, a large and a small geometric factor analyzer for electrons and a similar pair for ions, cover from approximately 3 eV to 30 keV. We present preliminary observations of the electron and ion distributions in the absence of obvious solar impulsive events and upstream particles. The quiet time electron energy spectrum shows a smooth approximately power law fall-off extending from the halo population at a few hundred eV to well above approximately 100 keV The quiet time ion energy spectrum also shows significant fluxes over this energy range. Detailed 3-D distributions and their temporal variations will be presented.

  17. 3-D Full-kinetic Simulations of the Solar Wind Interaction with Lunar Magnetic Anomalies: Particle Behaviour

    NASA Astrophysics Data System (ADS)

    Deca, J.; Divin, A. V.; Wang, X.; Lembege, B.; Markidis, S.; Lapenta, G.; Horanyi, M.

    2015-12-01

    We present three-dimensional full-kinetic electromagnetic simulations of the solar wind interaction with lunar crustal magnetic anomalies (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier MHD and hybrid simulations, the full-kinetic nature of iPic3D allows to self-consistently investigate space charge effects, and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe the general mechanism of the interaction of both a horizontal and vertical dipole model embedded just below the lunar surface focussing on the ion and electron kinetic behaviour of the system. It is shown that the configurations are largely dominated by electron motion, because the LMA scale size is small with respect to the gyro-radius of the solar wind ions. The formation of mini-magnetospheres is an electrostatic effect. Additionally, we discuss typical particle trajectories as well as complete particle distribution functions covering thermal and suprathermal energies, within the interaction region and on viable spacecraft altitudes. Our work opens new frontiers of research toward a deeper understanding of LMAs and is ideally suited to be compared with field or particle observations from spacecraft such as Kaguya (SELENE), Lunar Prospector or ARTEMIS. The ability to evaluate the implications for future lunar exploration as well as lunar science in general hinges on a better understanding of LMAs.This research has received funding from the European Commission's FP7 Program with the grant agreement EHEROES (project 284461, www.eheroes.eu). The simulations were conducted on the computational resources provided by the PRACE Tier-0 project 2013091928 (SuperMUC). This research was supported by the Swedish National Space Board

  18. Solar Wind Heating as Revealed from the Variation of 3D Ion Velocity Distributions across the Magnetic Reconnection Exhaust Region

    NASA Astrophysics Data System (ADS)

    He, J.

    2015-12-01

    Magnetic reconnection within current sheet has been regarded as one of the crucial dissipation and heating processes of coherent structures in the solar wind turbulence. Counter-streaming of ions is an important phenomenon in the reconnection exhaust region ranged from the ion diffusion region to the extended outflow region. It has been suggested by theoretical and numerical models that the ions are going to be picked up by the ejecting magnetic field and show larger T_perpendicular than T_parallel, if the guide field is strong enough (in other word, the shear angle is relatively low). The pick-up behavior seems to favor the heating of heavy ions with high mass-to-charge ratio, since the high M/Q ions have larger gyro-period/transit-time and tend to be non-adiabatic more easily. The above statements from theoretical models have not been thoroughly testified in the solar wind observations, though the changes in total temperature and 1D reduced velocity distribution function had been studied. Until now, it remains unclear about the difference of full 3D velocity distribution for the proton and helium ions between the upstream and the exhaust regions. Here, we will analyze the plasma measurement data from WIND/3DP to explore and compare the parallel and perpendicular heating effect of different species of ions. As a preliminary result, the proton is found to show bi-directional streams in its velocity distribution in some reconnection exhaust regions. The thermalization of the counter-streaming protons will be presented. The relation between proton T_parallel/T_perpendicular and guide field strength (or shear angle) will be studied. The velocity distributions of helium ions will be illustrated, which shows the difference of heating effect between different M/Q ratios.

  19. The Interaction of the Solar Wind with Solar Probe Plus - 3D Hybrid Simulation. Report 2: The Study for the Distance 9.5Rs

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Our paper is a 2.5D and 3D numerical plasma models of the interaction of the solar wind (SW) with the Solar Probe Plus spacecraft (SPPSC). These results should be interpreted as a basic plasma model for which the derived SW interaction with spacecraft (SC) could have consequences for both plasma wave and electron plasma measurements on board SC in the inner heliosphere. We observe an excitation of the low frequency Alfven and whistler type wave directed by the magnetic field with an amplitude of the electromagnetic field oscillation about of (0.015-0.06) V/m. The compression waves and the jumps in an electric field with an amplitude of about 1.5 V/m and (12-18) V/m were also observed. The observed strong electromagnetic perturbations may be a crucial point in the electromagnetic measurements, which were planned in future Solar Probe Plus mission.

  20. SMEI 3D RECONSTRUCTION OF A CORONAL MASS EJECTION INTERACTING WITH A COROTATING SOLAR WIND DENSITY ENHANCEMENT: THE 2008 APRIL 26 CME

    SciTech Connect

    Jackson, B. V.; Buffington, A.; Hick, P. P.; Clover, J. M.; Bisi, M. M.; Webb, D. F.

    2010-12-01

    The Solar Mass Ejection Imager (SMEI) has recorded the brightness responses of hundreds of interplanetary coronal mass ejections (CMEs) in the interplanetary medium. Using a three-dimensional (3D) reconstruction technique that derives its perspective views from outward-flowing solar wind, analysis of SMEI data has revealed the shapes, extents, and masses of CMEs. Here, for the first time, and using SMEI data, we report on the 3D reconstruction of a CME that intersects a corotating region marked by a curved density enhancement in the ecliptic. Both the CME and the corotating region are reconstructed and demonstrate that the CME disrupts the otherwise regular density pattern of the corotating material. Most of the dense CME material passes north of the ecliptic and east of the Sun-Earth line: thus, in situ measurements in the ecliptic near Earth and at the Solar-TErrestrial RElations Observatory Behind spacecraft show the CME as a minor density increase in the solar wind. The mass of the dense portion of the CME is consistent with that measured by the Large Angle Spectrometric Coronagraph on board the Solar and Heliospheric Observatory spacecraft, and is comparable to the masses of many other three-dimensionally reconstructed solar wind features at 1 AU observed in SMEI 3D reconstructions.

  1. Solar Wind Halo Formation by the Scattering of the Strahl via Direct Cluster/PEACE Observations of the 3D Velocity Distribution Function

    NASA Technical Reports Server (NTRS)

    Figueroa-Vinas, Adolfo; Gurgiolo, Chris A.; Nieves-Chinchilla, Teresa; Goldstein, Melvyn L.

    2010-01-01

    It has been suggested by a number of authors that the solar wind electron halo can be formed by the scattering of the strahl. On frequent occasions we have observed in electron angular skymaps (Phi/Theta-plots) of the electron 3D velocity distribution functions) a bursty-filament of particles connecting the strahl to the solar wind core-halo. These are seen over a very limited energy range. When the magnetic field is well off the nominal solar wind flow direction such filaments are inconsistent with any local forces and are probably the result of strong scattering. Furthermore, observations indicates that the strahl component is frequently and significantly anisotropic (Tper/Tpal approx.2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism. The empirical observational evidence between the halo and the strahl suggests that the strahl population may be, at least in part, the source of the halo component.

  2. The Interaction of the Solar Wind with Solar Probe Plus - 3D Hybrid Simulation. Report 1; The Study for the Distance 4.5Rs

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Our report devotes a 3D numerical hybrid model of the interaction of the solar wind with the Solar Probe spacecraft. The Solar Probe Plus (SPP) model includes 3 main parts, namely, a non-conducting heat shield, a support system, and cylindrical section or spacecraft bus that contains the particle analysis devices and antenna. One observes an excitation of the low frequency Alfven and whistler type wave directed by the magnetic field with an amplitude of about (0.06-0.6) V/m. The compression waves and the jumps in an electric field with an amplitude of about (0.15-0.7) V/m were also observed. The wave amplitudes are comparable to or greater than previously estimated max wave amplitudes that SPP is expected to measure. The results of our hybrid simulation will be useful for understanding the plasma environment near the SPP spacecraft at the distance 4.5 Rs. Future simulation will take into account the charging of the spacecraft, the charge separation effects, an outgassing from heat shield, a photoionization and an electron impact ionization effects near the spacecraft.

  3. The Interaction of the Solar Wind with Solar Probe Plus - 3D Hybrid Simulation. Report 1; The Study for the Distance 4.5Rs

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Our report devotes a 3D numerical hybrid model of the interaction of the solar wind with the Solar Probe spacecraft. The SPP model includes 3 main parts, namely, a non-conducting heat shield, a support system, and cylindrical section or spacecraft bus that contains the particle analysis devices and antenna. One observes an excitation of the low frequency Alfven and whistler type wave directed by the magnetic field with an amplitude of about (0.06-0.6) V/m. The compression waves and the jumps in an electric field with an amplitude of about (0.15-0.7) V/m were also observed. The wave amplitudes are comparable to or greater than previously estimated max wave amplitudes that SPP is expected to measure. The results of our hybrid simulation will be useful for understanding the plasma environment near the SPP spacecraft at the distance 4.5 Rs. Future simulation will take into account the charging of the spacecraft, the charge separation effects, an outgassing from heat shield, a photoionization and an electron impact ionization effects near the spacecraft.

  4. Solwnd: A 3D Compressible MHD Code for Solar Wind Studies. Version 1.0: Cartesian Coordinates

    NASA Technical Reports Server (NTRS)

    Deane, Anil E.

    1996-01-01

    Solwnd 1.0 is a three-dimensional compressible MHD code written in Fortran for studying the solar wind. Time-dependent boundary conditions are available. The computational algorithm is based on Flux Corrected Transport and the code is based on the existing code of Zalesak and Spicer. The flow considered is that of shear flow with incoming flow that perturbs this base flow. Several test cases corresponding to pressure balanced magnetic structures with velocity shear flow and various inflows including Alfven waves are presented. Version 1.0 of solwnd considers a rectangular Cartesian geometry. Future versions of solwnd will consider a spherical geometry. Some discussions of this issue is presented.

  5. 3D numerical study of the propagation characteristics of a consequence of coronal mass ejections in a structured ambient solar wind

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Feng, X. S.

    2015-12-01

    CMEs have been identified as a prime causal link between solar activity and large, nonrecurrent geomagnetic storm. In order to improve geomagnetic storm predictions, a careful study of CME's propagation characteristics is important. Here, we analyze and quantitatively study the evolution and propagation characteristics of coronal mass ejections (CMEs) launched at several positions into a structured real ambient solar wind by using a three-dimensional (3D) numerical magnetohydrodynamics (MHD) simulation. The ambient solar wind structure during Carrington rotation 2095 is selected, which is an appropriate around activity minimum and declining phase. The CME is initiated by a simple spherical plasmoid model: a spheromak magnetic structure with high speed, high pressure and high plasma density plasmoid. We present a detailed analysis of the plasma, magnetic field, geoeffectiveness, and composition signatures of these CMEs. Results show that the motion and local appearance of a CME in interplanetary space is strongly affected by its interaction with the background solar wind structure, including its velocity, density, and magnetic structures. The simulations show that the initial launched position substantially affects the IP evolution of the CMEs influencing the propagation velocity, the shape, the trajectory and even the geo-effectiveness

  6. Mars-solar wind interaction: LatHyS, an improved parallel 3-D multispecies hybrid model

    NASA Astrophysics Data System (ADS)

    Modolo, Ronan; Hess, Sebastien; Mancini, Marco; Leblanc, Francois; Chaufray, Jean-Yves; Brain, David; Leclercq, Ludivine; Esteban-Hernández, Rosa; Chanteur, Gerard; Weill, Philippe; González-Galindo, Francisco; Forget, Francois; Yagi, Manabu; Mazelle, Christian

    2016-07-01

    In order to better represent Mars-solar wind interaction, we present an unprecedented model achieving spatial resolution down to 50 km, a so far unexplored resolution for global kinetic models of the Martian ionized environment. Such resolution approaches the ionospheric plasma scale height. In practice, the model is derived from a first version described in Modolo et al. (2005). An important effort of parallelization has been conducted and is presented here. A better description of the ionosphere was also implemented including ionospheric chemistry, electrical conductivities, and a drag force modeling the ion-neutral collisions in the ionosphere. This new version of the code, named LatHyS (Latmos Hybrid Simulation), is here used to characterize the impact of various spatial resolutions on simulation results. In addition, and following a global model challenge effort, we present the results of simulation run for three cases which allow addressing the effect of the suprathermal corona and of the solar EUV activity on the magnetospheric plasma boundaries and on the global escape. Simulation results showed that global patterns are relatively similar for the different spatial resolution runs, but finest grid runs provide a better representation of the ionosphere and display more details of the planetary plasma dynamic. Simulation results suggest that a significant fraction of escaping O+ ions is originated from below 1200 km altitude.

  7. Application of rank-ordered multifractal analysis (ROMA) to intermittent fluctuations in 3D turbulent flows, 2D MHD simulation and solar wind data

    NASA Astrophysics Data System (ADS)

    Wu, C.; Chang, T.

    2010-12-01

    A new method in describing the multifractal characteristics of intermittent events was introduced by Cheng and Wu [Chang T. and Wu C.C., Physical Rev, E77, 045401(R), 2008]. The procedure provides a natural connection between the rank-ordered spectrum and the idea of one-parameter scaling for monofractals. This technique has been demonstrated using results obtained from a 2D MHD simulation. It has also been successfully applied to in-situ solar wind observations [Chang T., Wu, C.C. and Podesta, J., AIP Conf Proc. 1039, 75, 2008], and the broadband electric field oscillations from the auroral zone [Tam, S.W.Y. et al., Physical Rev, E81, 036414, 2010]. We take the next step in this procedure. By using the ROMA spectra and the scaled probability distribution functions (PDFs), raw PDFs can be calculated, which can be compared directly with PDFs from observations or simulation results. In addition to 2D MHD simulation results and in-situ solar wind observation, we show clearly using the ROMA analysis the multifractal character of the 3D fluid simulation data obtained from the JHU turbulence database cluster at http://turbulence.pha.jhu.edu. In particular, we show the scaling of the non-symmetrical PDF for the parallel-velocity fluctuations of this 3D fluid data.

  8. Solar Wind Halo Formation by the Scattering of the Strahl: Direct Cluster/PEACE Observations of the 3D Velocity Distribution Function

    NASA Astrophysics Data System (ADS)

    Vinas, A. F.; Gurgiolo, C. A.; Nieves-Chinchilla, T.; Wendel, D. E.; Goldstein, M. L.; Fazakerley, A. N.

    2010-12-01

    The current hypothesis of the formation of the solar wind halo electrons is that they are produced from scattering of the strahl. This hypothesis is strengthened by direct observations of the strahl electrons being scattered into the halo in an isolated event. On frequent occasions we have observed in electron angular skymaps (Phi/Theta-plots) of the electron 3D velocity distribution functions, a bursty-filament of particles connecting the strahl to the solar wind core-halo. These are seen over a limited energy range. The observation implies that the formation of the halo is not a continuous process but occurs in bursts in regions where conditions for wave growth providing the scattering are optimum. Sometimes, observations indicates that the strahl component is anisotropic (Tper/Tpal ~ 2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism, however this condition is not always observed. The empirical observational evidence between the halo and the strahl suggests that the strahl population may be, at least in part, the source of the halo component.

  9. The 3-D effects in the long-term solar wind speed rise observed by Voyager 2 in early 1994

    NASA Technical Reports Server (NTRS)

    Pizzo, V. J.; Paularena, K. I.; Richardson, J. D.; Lazarus, A. J.; Belcher, J. W.

    1995-01-01

    In early 1994, Voyager 2 at 42-43 AU near heliolatitude 10 deg S observed over a period of approximately 100 days a remarkable sequence of quasi-recurrent stream fronts, wherein the background (ambient) speed rose steadily from approximately 450 to approximately 550 km/s while the mean period of the streams decreased from the usual 25 days down to approximately 20 days. A qualitative explanation for this effect can be derived from IMP observations, which show that the amplitude of the stream structure at 1 AU increased monotonically in late 1993, concurrent with major secular evolution in the corona. The reduction in period, then, amounts to a doppler shift due to the progressive overtaking of successively faster streams in the sequence. Attempts to model this process quantitatively with 1-D dynamic simulations falter on three accounts: (1) the reduction in period is overestimated, (2) the simulation predicts many more fronts surviving to 43 AU than are observed by Voyager; (3) the density variations are much too large. It is argued that inclusion of the 3-D geometry in the simulation would resolve most all these shortcomings. Using a series of calculations executed with 1-D, 2-D, and 3-D MHD models of hypothetical tilted-dipole flows, we show that: (1) the radial propagation velocities of 3-D fronts are less than those of 1-D or 2-D fronts, owing to the tilt of (and increased shearing across) the interaction surfaces hence the overtaking rate of successive streams is reduced; (2) in a tilted-dipole geometry, the reverse fronts should largely disappear from the equatorial plane by 43 AU, effectively halving the number of fronts to be observed (see companion paper on predominance of forward fronts at Voyager); and (3) the density enhancements would be much smaller than predicted by a 1-D model.

  10. World Wind 3D Earth Viewing

    NASA Technical Reports Server (NTRS)

    Hogan, Patrick; Maxwell, Christopher; Kim, Randolph; Gaskins, Tom

    2007-01-01

    World Wind allows users to zoom from satellite altitude down to any place on Earth, leveraging high-resolution LandSat imagery and SRTM (Shuttle Radar Topography Mission) elevation data to experience Earth in visually rich 3D. In addition to Earth, World Wind can also visualize other planets, and there are already comprehensive data sets for Mars and the Earth's moon, which are as easily accessible as those of Earth. There have been more than 20 million downloads to date, and the software is being used heavily by the Department of Defense due to the code s ability to be extended and the evolution of the code courtesy of NASA and the user community. Primary features include the dynamic access to public domain imagery and its ease of use. All one needs to control World Wind is a two-button mouse. Additional guides and features can be accessed through a simplified menu. A JAVA version will be available soon. Navigation is automated with single clicks of a mouse, or by typing in any location to automatically zoom in to see it. The World Wind install package contains the necessary requirements such as the .NET runtime and managed DirectX library. World Wind can display combinations of data from a variety of sources, including Blue Marble, LandSat 7, SRTM, NASA Scientific Visualization Studio, GLOBE, and much more. A thorough list of features, the user manual, a key chart, and screen shots are available at http://worldwind.arc.nasa.gov.

  11. 3D Wind: Quantifying wind speed and turbulence intensity

    NASA Astrophysics Data System (ADS)

    Barthelmie, R. J.; Pryor, S. C.; Wang, H.; Crippa, P.

    2013-12-01

    Integrating measurements and modeling of wind characteristics for wind resource assessment and wind farm control is increasingly challenging as the scales of wind farms increases. Even offshore or in relatively homogeneous landscapes, there are significant gradients of both wind speed and turbulence intensity on scales that typify large wind farms. Our project is, therefore, focused on (i) improving methods to integrate remote sensing and in situ measurements with model simulations to produce a 3-dimensional view of the flow field on wind farm scales and (ii) investigating important controls on the spatiotemporal variability of flow fields within the coastal zone. The instrument suite deployed during the field experiments includes; 3-D sonic and cup anemometers deployed on meteorological masts and buoys, anemometers deployed on tethersondes and an Unmanned Aerial Vehicle, multiple vertically-pointing continuous-wave lidars and scanning Doppler lidars. We also integrate data from satellite-borne instrumentation - specifically synthetic aperture radar and scatterometers and output from the Weather Research and Forecast (WRF) model. Spatial wind fields and vertical profiles of wind speed from WRF and from the full in situ observational suite exhibit excellent agreement in a proof-of-principle experiment conducted in north Indiana particularly during convective conditions, but showed some discrepancies during the breakdown of the nocturnal stable layer. Our second experiment in May 2013 focused on triangulating a volume above an area of coastal water extending from the port in Cleveland out to an offshore water intake crib (about 5 km) and back to the coast, and includes extremely high resolution WRF simulations designed to characterize the coastal zone. Vertically pointing continuous-wave lidars were operated at each apex of the triangle, while the scanning Doppler lidar scanned out across the water over 90 degrees azimuth angle. Preliminary results pertaining to

  12. First 3D view of solar eruptions

    NASA Astrophysics Data System (ADS)

    2004-07-01

    loops, rather than a bubble or rope-like structure. Although this technique had been independently developed previously to study relatively static structures in the solar atmosphere during eclipses, this is the first time that it is applied to fast moving CMEs. Moran and Davila believe that their method will complement data from the upcoming NASA’s Solar Terrestrial Relations Observatory (STEREO) mission, scheduled for launch in February 2006. STEREO will use two widely separated spacecraft to construct 3D views of CMEs by combining images from the different vantage points of the twin spacecraft. Commenting on this result, Bernhard Fleck, SOHO Project Scientist at ESA, said: "These are really amazing images. Once again scientists have come up with a clever idea for analysing SOHO data in ways that were not even dreamt of when the mission was designed." Movie: http://esamultimedia.esa.int/images/spcs/soho/soho20040702.mpg 3 stills from the movie http://esamultimedia.esa.int/images/spcs/soho/soho20040702c.tiff http://esamultimedia.esa.int/images/spcs/soho/soho20040702d.tiff http://esamultimedia.esa.int/images/spcs/soho/soho20040702e.tiff This movie shows a 3D rendering of the data in Figure 2. It starts out viewing the Sun from SOHO's perspective, then rotates the scene to view the data from the side, and finally from the top. Note that one distinct feature shown at about 11 o'clock in Figure 2 panel a has been left out of the movie, because it is a static structure and not a part of the CME. Notes to Editors: This new result by T. Moran and J. Davila is published in today’s issue of the magazine Science. More about SOHO SOHO is a project of international co-operation between ESA and NASA to study the Sun, from its deep core to the outer corona, and the solar wind. Fourteen European countries, led by the European Space Agency and prime contractor Astrium (formerly Matra-Marconi), built the SOHO spacecraft. It carries twelve instruments (nine European-led and three

  13. General mechanism and dynamics of the solar wind interaction with lunar magnetic anomalies from 3-D particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Deca, Jan; Divin, Andrey; Lembège, Bertrand; Horányi, Mihály; Markidis, Stefano; Lapenta, Giovanni

    2015-08-01

    We present a general model of the solar wind interaction with a dipolar lunar crustal magnetic anomaly (LMA) using three-dimensional full-kinetic and electromagnetic simulations. We confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface, forming a so-called "minimagnetosphere," as suggested by spacecraft observations and theory. We show that the LMA configuration is driven by electron motion because its scale size is small with respect to the gyroradius of the solar wind ions. We identify a population of back-streaming ions, the deflection of magnetized electrons via the E × B drift motion, and the subsequent formation of a halo region of elevated density around the dipole source. Finally, it is shown that the presence and efficiency of the processes are heavily impacted by the upstream plasma conditions and, on their turn, influence the overall structure and evolution of the LMA system. Understanding the detailed physics of the solar wind interaction with LMAs, including magnetic shielding, particle dynamics and surface charging is vital to evaluate its implications for lunar exploration.

  14. Solar carbon monoxide: poster child for 3D effects .

    NASA Astrophysics Data System (ADS)

    Ayres, T. R.; Lyons, J. R.; Ludwig, H.-G.; Caffau, E.; Wedemeyer-Böhm, S.

    Photospheric infrared (2-6 mu m) rovibrational bands of carbon monoxide (CO) provide a tough test for 3D convection models such as those calculated using CO5BOLD. The molecular formation is highly temperature-sensitive, and thus responds in an exaggerated way to thermal fluctuations in the dynamic atmosphere. CO, itself, is an important tracer of the oxygen abundance, a still controversial issue in solar physics; as well as the heavy isotopes of carbon (13C) and oxygen (18O, 17O), which, relative to terrestrial values, are fingerprints of fractionation processes that operated in the primitive solar nebula. We show how 3D models impact the CO line formation, and add in a second constraint involving the near-UV Ca RIPTSIZE II line wings, which also are highly temperature sensitive, but in the opposite sense to the molecules. We find that our reference CO5BOLD snapshots appear to be slightly too cool on average in the outer layers of the photosphere where the CO absorptions and Ca RIPTSIZE II wing emissions arise. We show, further, that previous 1D modeling was systematically biased toward higher oxygen abundances and lower isotopic ratios (e.g., R23equiv 12C/13C), suggesting an isotopically ``heavy'' Sun contrary to direct capture measurements of solar wind light ions by the Genesis Discovery Mission. New 3D ratios for the oxygen isotopes are much closer to those reported by Genesis, and the associated oxygen abundance from CO now is consistent with the recent Caffau et al. study of atomic oxygen. Some lingering discrepancies perhaps can be explained by magnetic bright points. Solar CO demonstrates graphically the wide gulf that can occur between a 3D analysis and 1D.

  15. Solar wind interaction with Mars' upper atmosphere: Results from 3-D studies using one-way coupling between the Multi-fluid MHD, the M-GITM and the AMPS models

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The study of the solar wind interaction with Mars upper atmosphere/ionosphere has triggered a great of interest in recent years. Among the large number of topics in this research area, the investigation of ion escape fluxes has become increasingly 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 (100km~5RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model outputs fields into the 3-D BATS-R-US Mars multi-fluid MHD model (100km~20RM) that can better simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid 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, allowing 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 outputs are used as the inputs for the multi-fluid model and M-GITM is used as input into the AMPS exosphere model. The calculations are carried out for selected cases with different nominal solar wind, solar cycle and crustal field orientation conditions. This work has the potential to provide predictions of ion escape rates for comparison to future data to be returned by the MAVEN primary mission (2014-2016) and thereby improve our understanding of present day escape processes. Acknowledgments: The work presented here was supported by NASA grants NNH10CC04C, NNX09AL26G, NSF grant ATM-0535811.

  16. Transforming Wind Turbine Blade Mold Manufacturing with 3D Printing

    SciTech Connect

    Zayas, Jose; Johnson, Mark

    2016-06-28

    Innovation in the design and manufacturing of wind power generation components continues to be critical to achieving our national renewable energy goals. As a result of this challenge, the U.S. Department of Energy's Wind Program and Advanced Manufacturing Office are partnering with public and private organizations to apply additive manufacturing, commonly known as 3D printing, to the production of wind turbine blade molds.

  17. Transforming Wind Turbine Blade Mold Manufacturing with 3D Printing

    ScienceCinema

    Zayas, Jose; Johnson, Mark

    2016-08-17

    Innovation in the design and manufacturing of wind power generation components continues to be critical to achieving our national renewable energy goals. As a result of this challenge, the U.S. Department of Energy's Wind Program and Advanced Manufacturing Office are partnering with public and private organizations to apply additive manufacturing, commonly known as 3D printing, to the production of wind turbine blade molds.

  18. Use of 3D Printing for Custom Wind Tunnel Fabrication

    NASA Astrophysics Data System (ADS)

    Gagorik, Paul; Bates, Zachary; Issakhanian, Emin

    2016-11-01

    Small-scale wind tunnels for the most part are fairly simple to produce with standard building equipment. However, the intricate bell housing and inlet shape of an Eiffel type wind tunnel, as well as the transition from diffuser to fan in a rectangular tunnel can present design and construction obstacles. With the help of 3D printing, these shapes can be custom designed in CAD models and printed in the lab at very low cost. The undergraduate team at Loyola Marymount University has built a custom benchtop tunnel for gas turbine film cooling experiments. 3D printing is combined with conventional construction methods to build the tunnel. 3D printing is also used to build the custom tunnel floor and interchangeable experimental pieces for various experimental shapes. This simple and low-cost tunnel is a custom solution for specific engineering experiments for gas turbine technology research.

  19. Solar Wind Five

    NASA Technical Reports Server (NTRS)

    Neugebauer, M. (Editor)

    1983-01-01

    Topics of discussion were: solar corona, MHD waves and turbulence, acceleration of the solar wind, stellar coronae and winds, long term variations, energetic particles, plasma distribution functions and waves, spatial dependences, and minor ions.

  20. Solar wind models

    NASA Technical Reports Server (NTRS)

    Leer, Egil; Sandbaek, Ornulf

    1991-01-01

    The understanding of the solar wind is based upon Parker's (1958) description of a thermally driven subsonic - supersonic outflow from a fully ionized electron-proton corona. The basic physical processes of thermally driven solar wind models are discussed. Also studied are the effect of alpha particles in the corona on the solar wind proton flux. The acceleration of the solar wind by Alfven waves is discussed.

  1. Magnetocentrifugal Winds in 3D: Nonaxisymmetric Steady State

    SciTech Connect

    Anderson, Jeffrey M.; Li, Zhi-Yun; Krasnopolsky, Ruben; Blandford, Roger D.; /SLAC

    2006-11-28

    Outflows can be loaded and accelerated to high speeds along rapidly rotating, open magnetic field lines by centrifugal forces. Whether such magnetocentrifugally driven winds are stable is a longstanding theoretical problem. As a step towards addressing this problem, we perform the first large-scale 3D MHD simulations that extend to a distance {approx} 10{sup 2} times beyond the launching region, starting from steady 2D (axisymmetric) solutions. In an attempt to drive the wind unstable, we increase the mass loading on one half of the launching surface by a factor of {radical}10, and reduce it by the same factor on the other half. The evolution of the perturbed wind is followed numerically. We find no evidence for any rapidly growing instability that could disrupt the wind during the launching and initial phase of propagation, even when the magnetic field of the magnetocentrifugal wind is toroidally dominated all the way to the launching surface. The strongly perturbed wind settles into a new steady state, with a highly asymmetric mass distribution. The distribution of magnetic field strength is, in contrast, much more symmetric. We discuss possible reasons for the apparent stability, including stabilization by an axial poloidal magnetic field, which is required to bend field lines away from the vertical direction and produce a magnetocentrifugal wind in the first place.

  2. 3D wind field from spaceborne Doppler radar

    NASA Astrophysics Data System (ADS)

    Lemaître, Y.; Viltard, N.

    2013-10-01

    Numerous space radar missions are presently envisioned to study the water cycle in the tropics. Among them, the DYCECT (DYnamique, énergie et Cycle de l'Eau dans la Convection Tropicale) mission, a French proposal (submitted to the French CNES Agency), could embark a Doppler radar (W-band or Ka-band) with scanning possibilities onboard a low-orbiting satellite. This instrument could be implemented in addition to a Passive Microwave Radiometer (PMR), and eventually an improved ScaraB-like broadband radiometer, and a lightning detection instrument. This package will document the ice microphysics and the heat budgets. Since the microphysics and the water and energy budgets are strongly driven by the dynamics, the addition of a Doppler radar with scanning possibilities could provide valuable information (3D wind and rain fields) and a large statistic of such critical information over the entire tropics and for all the stages of development. These new information could be used to better understand the tropical convection and to improve convection parameterization relevant for cloud and climate models. It could be used also to associate direct applications such as now-casting and risk prevention. The present study focuses on the feasibility of such 3D wind field retrieval from spaceborne radar. It uses a simulator of some parts of the spaceborne radar in order i) to evaluate the sensitivity of the retrieved wind fields to the scanning strategies and sampling parameters, and to the instrumental and platform parameters and ii) to determine the best parameters providing the most accurate wind fields.

  3. 3D wind field retrieval from spaceborne Doppler radar

    NASA Astrophysics Data System (ADS)

    Lemaêtre, Y.; Viltard, N.

    2012-11-01

    Numerous space missions carrying a radar are presently envisioned, particularly to study tropical rain systems. Among those missions, BOITATA is a joint effort between Brazil (INPE/AEB) and France (CNES). The goal is to embark a Doppler radar with scanning possibilities onboard a low-orbiting satellite. This instrument should be implemented in addition to a Passive Microwave Radiometer (PMR) between 19 and 183 GHz, an improved ScaraB-like broadband radiometer, a mm/submm PMR and a lightning detection instrument. This package would be meant to document the feedback of the ice microphysics on the rain systems life cycle and on their heat and radiative budgets. Since the microphysics and the water and energy budgets are strongly driven by the dynamics, the addition of a Doppler radar with scanning possibilities could provide precious information (3D wind and rain fields). It would allow us to build a large statistics of such critical information over the entire tropics and for all the stages of development of the convection. This information could be used to better understand the tropical convection and to improve convection parameterization relevant for cloud and climate models and associated applications such as now-casting and risk prevention. The present work focuses on the feasibility to retrieve 3D winds in precipitating areas from such a radar. A simulator of some parts of the spaceborne radar is developed to estimate the precision on the retrieved wind field depending on the scanning strategies and instrumental parameters and to determine the best sampling parameters.

  4. Comparative visual analysis of 3D urban wind simulations

    NASA Astrophysics Data System (ADS)

    Röber, Niklas; Salim, Mohamed; Grawe, David; Leitl, Bernd; Böttinger, Michael; Schlünzen, Heinke

    2016-04-01

    Climate simulations are conducted in large quantity for a variety of different applications. Many of these simulations focus on global developments and study the Earth's climate system using a coupled atmosphere ocean model. Other simulations are performed on much smaller regional scales, to study very small fine grained climatic effects. These microscale climate simulations pose similar, yet also different, challenges for the visualization and the analysis of the simulation data. Modern interactive visualization and data analysis techniques are very powerful tools to assist the researcher in answering and communicating complex research questions. This presentation discusses comparative visualization for several different wind simulations, which were created using the microscale climate model MITRAS. The simulations differ in wind direction and speed, but are all centered on the same simulation domain: An area of Hamburg-Wilhelmsburg that hosted the IGA/IBA exhibition in 2013. The experiments contain a scenario case to analyze the effects of single buildings, as well as examine the impact of the Coriolis force within the simulation. The scenario case is additionally compared with real measurements from a wind tunnel experiment to ascertain the accuracy of the simulation and the model itself. We also compare different approaches for tree modeling and evaluate the stability of the model. In this presentation, we describe not only our workflow to efficiently and effectively visualize microscale climate simulation data using common 3D visualization and data analysis techniques, but also discuss how to compare variations of a simulation and how to highlight the subtle differences in between them. For the visualizations we use a range of different 3D tools that feature techniques for statistical data analysis, data selection, as well as linking and brushing.

  5. Solar Wind Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Smith, E. J.

    1995-01-01

    The magnetic fields originate as coronal fields that are converted into space by the supersonic, infinitely conducting, solar wind. On average, the sun's rotation causes the field to wind up and form an Archimedes Spiral. However, the field direction changes almost continuously on a variety of scales and the irregular nature of these changes is often interpreted as evidence that the solar wind flow is turbulent.

  6. 3D model atmospheres and the solar photospheric oxygen abundance

    NASA Astrophysics Data System (ADS)

    Caffau, E.; Ludwig, H.-G.

    2008-10-01

    In recent years the photospheric solar oxygen abundance experienced a significant downward revision. However, a low photospheric abundance is incompatible with the value in the solar interior inferred from helioseismology. For contributing to the dispute whether the solar oxygen abundance is “high” or “low”, we re-derived its photospheric abundance independently of previous analyses. We applied 3D (CO5BOLD) as well as 1D model atmospheres. We considered standard disc-centre and disc-integrated spectral atlases, as well as newly acquired solar intensity spectra at different heliocentric angles. We determined the oxygen abundances from equivalent width and/or line profile fitting of a number of atomic lines. As preliminary result, we find an oxygen abundance in the range 8.73 8.79, encompassing the value obtained by Holweger (2001), and somewhat higher than the value obtained by Asplund et al. (2005).

  7. C3Winds: A Novel 3D Wind Observing System to Characterize Severe Weather Events

    NASA Astrophysics Data System (ADS)

    Kelly, M. A.; Wu, D. L.; Yee, J. H.; Boldt, J.; Demajistre, R.; Reynolds, E.; Tripoli, G. J.; Oman, L.; Prive, N.; Heidinger, A. K.; Wanzong, S.

    2015-12-01

    The CubeSat Constellation Cloud Winds (C3Winds) is a NASA Earth Venture Instrument (EV-I) concept with the primary objective to resolve high-resolution 3D dynamic structures of severe wind events. Rapid evolution of severe weather events highlights the need for high-resolution mesoscale wind observations. Yet mesoscale observations of severe weather dynamics are quite rare, especially over the ocean where extratropical and tropical cyclones (ETCs and TCs) can undergo explosive development. Measuring wind velocity at the mesoscale from space remains a great challenge, but is critically needed to understand and improve prediction of severe weather and tropical cyclones. Based on compact, visible/IR imagers and a mature stereoscopic technique, C3Winds has the capability to measure high-resolution (~2 km) cloud motion vectors and cloud geometric heights accurately by tracking cloud features from two formation-flying CubeSats, separated by 5-15 minutes. Complementary to lidar wind measurements from space, C3Winds will provide high-resolution wind fields needed for detailed investigations of severe wind events in occluded ETCs, rotational structures inside TC eyewalls, and ozone injections associated with tropopause folding events. Built upon mature imaging technologies and long history of stereoscopic remote sensing, C3Winds provides an innovative, cost-effective solution to global wind observations with the potential for increased diurnal sampling via CubeSat constellation.

  8. Flank solar wind interaction

    NASA Technical Reports Server (NTRS)

    Moses, Stewart L.; Greenstadt, Eugene W.; Coroniti, Ferdinand V.

    1994-01-01

    In this report we will summarize the results of the work performed under the 'Flank Solar Wind Interaction' investigation in support of NASA's Space Physics Guest Investigator Program. While this investigation was focused on the interaction of the Earth's magnetosphere with the solar wind as observed by instruments on the International Sun-Earth Explorer (ISEE) 3 spacecraft, it also represents the culmination of decades of research performed by scientists at TRW on the rich phenomenology of collisionless shocks in space.

  9. 3D-printed external light trap for solar cells.

    PubMed

    van Dijk, Lourens; Paetzold, Ulrich W; Blab, Gerhard A; Schropp, Ruud E I; di Vece, Marcel

    2016-05-01

    We present a universally applicable 3D-printed external light trap for enhanced absorption in solar cells. The macroscopic external light trap is placed at the sun-facing surface of the solar cell and retro-reflects the light that would otherwise escape. The light trap consists of a reflective parabolic concentrator placed on top of a reflective cage. Upon placement of the light trap, an improvement of 15% of both the photocurrent and the power conversion efficiency in a thin-film nanocrystalline silicon (nc-Si:H) solar cell is measured. The trapped light traverses the solar cell several times within the reflective cage thereby increasing the total absorption in the cell. Consequently, the trap reduces optical losses and enhances the absorption over the entire spectrum. The components of the light trap are 3D printed and made of smoothened, silver-coated thermoplastic. In contrast to conventional light trapping methods, external light trapping leaves the material quality and the electrical properties of the solar cell unaffected. To explain the theoretical operation of the external light trap, we introduce a model that predicts the absorption enhancement in the solar cell by the external light trap. The corresponding calculated path length enhancement shows good agreement with the empirically derived value from the opto-electrical data of the solar cell. Moreover, we analyze the influence of the angle of incidence on the parasitic absorptance to obtain full understanding of the trap performance. © 2015 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons, Ltd.

  10. Basics of the Solar Wind

    NASA Astrophysics Data System (ADS)

    Meyer-Vernet, Nicole

    2012-09-01

    Preface; 1. The wind from the sun: an introduction; 2. Toolkit for space plasma physics; 3. Anatomy of the sun; 4. The outer solar atmosphere; 5. How does the solar wind blow?; 6. Structure and perturbations; 7. Bodies in the wind: dust, asteroids, planets and comets; 8. The solar wind in the universe; Index.

  11. 3D radiative transfer in colliding wind binaries: Application of the SimpleX algorithm to 3D SPH simulations

    NASA Astrophysics Data System (ADS)

    Madura, Thomas; Clementel, Nicola; Kruip, Chael; Icke, Vincent; Gull, Theodore

    2014-09-01

    We present the first results of full 3D radiative transfer simulations of the colliding stellar winds in a massive binary system. We accomplish this by applying the SIMPLEX algorithm for 3D radiative transfer on an unstructured Delaunay grid to recent 3D smoothed particle hydrodynamics (SPH) simulations of the colliding winds in the binary system η Carinae. We use SIMPLEX to obtain detailed ionization fractions of hydrogen and helium, in 3D, at the resolution of the original SPH simulations. We show how the SIMPLEX simulations can be used to generate synthetic spectral data cubes for comparison to data obtained with the Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph as part of a multi-cycle program to map changes in η Car's extended interacting wind structures across one binary cycle. Comparison of the HST observations to the SIMPLEX models can help lead to more accurate constraints on the orbital, stellar, and wind parameters of the η Car system, such as the primary's mass-loss rate and the companion's temperature and luminosity. While we initially focus specifically on the η Car binary, the numerical methods employed can be applied to numerous other colliding wind (WR140, WR137, WR19) and dusty 'pinwheel' (WR104, WR98a) binary systems. One of the biggest remaining mysteries is how dust can form and survive in such systems that contain a hot, luminous O star. Coupled with 3D hydrodynamical simulations, SIMPLEX simulations have the potential to help determine the regions where dust can form and survive in these unique objects.

  12. 3-D MHD disk wind simulations of protostellar jets

    NASA Astrophysics Data System (ADS)

    Staff, Jan E.; Koning, Nico; Ouyed, Rachid; Tanaka, Kei; Tan, Jonathan C.

    2016-01-01

    We present the results of large scale, three-dimensional magnetohydrodynamics simulations of disk winds for different initial magnetic field configurations. The jets are followed from the source to distances, which are resolvable by HST and ALMA observations. Our simulations show that jets are heated along their length by many shocks. The mass of the protostar is a free parameter that can be inserted in the post processing of the data, and we apply the simulations to both low mass and high mass protostars. For the latter we also compute the expected diagnostics when the outflow is photoionized by the protostar. We compute the emission lines that are produced, and find excellent agreement with observations. For a one solar mass protostar, we find the jet width to be between 20 and 30 au while the maximum velocities perpendicular to the jet are found to be 100 km s-1. The initially less open magnetic field configuration simulations result in a wider, two-component jet; a cylindrically shaped outer jet surrounding a narrow and much faster, inner jet. For the initially most open magnetic field configuration the kink mode creates a narrow corkscrew-like jet without a clear Keplerian rotation profile and even regions where we observe rotation opposite to the disk (counter-rotating). This is not seen in the less open field configurations.

  13. 3-D Hybrid Kinetic Modeling of the Interaction Between the Solar Wind and Lunar-like Exospheric Pickup Ions in Case of Oblique/ Quasi-Parallel/Parallel Upstream Magnetic Field

    NASA Technical Reports Server (NTRS)

    Lipatov, A. S.; Farrell, W. M.; Cooper, J. F.; Sittler, E. C., Jr.; Hartle, R. E.

    2015-01-01

    The interactions between the solar wind and Moon-sized objects are determined by a set of the solar wind parameters and plasma environment of the space objects. The orientation of upstream magnetic field is one of the key factors which determines the formation and structure of bow shock wave/Mach cone or Alfven wing near the obstacle. The study of effects of the direction of the upstream magnetic field on lunar-like plasma environment is the main subject of our investigation in this paper. Photoionization, electron-impact ionization and charge exchange are included in our hybrid model. The computational model includes the self-consistent dynamics of the light (hydrogen (+), helium (+)) and heavy (sodium (+)) pickup ions. The lunar interior is considered as a weakly conducting body. Our previous 2013 lunar work, as reported in this journal, found formation of a triple structure of the Mach cone near the Moon in the case of perpendicular upstream magnetic field. Further advances in modeling now reveal the presence of strong wave activity in the upstream solar wind and plasma wake in the cases of quasiparallel and parallel upstream magnetic fields. However, little wave activity is found for the opposite case with a perpendicular upstream magnetic field. The modeling does not show a formation of the Mach cone in the case of theta(Sub B,U) approximately equal to 0 degrees.

  14. Flare Particle Escape in 3D Solar Eruptive Events

    NASA Astrophysics Data System (ADS)

    Antiochos, Spiro K.; Masson, Sophie; DeVore, C. R.

    2015-04-01

    Among the most important, but least understood forms of space weather are the so-called Impulsive Solar Energetic Particle (SEP) events, which can be especially hazardous to deep-space astronauts. These energetic particles are generally believed to be produced by the flare reconnection that is the primary driver of solar eruptive events (SEE). A key point is that in the standard model of SEEs, the particles should remain trapped in the coronal flare loops and in the ejected plasmoid, the CME. However, flare-accelerated particles frequently reach the Earth long before the CME does. In previous 2.5D calculations we showed how the external reconnection that is an essential element of the breakout model for CME initiation could lead to the escape of flare-accelerated particles. The problem, however, is that in 2.5D this reconnection also tends to destroy the plasmoid, which disagrees with the observation that SEP events are often associated with well-defined plasmoids at 1 AU known as “magnetic clouds”. Consequently, we have extended our model to a fully 3D topology that includes a multi-polar coronal field suitable for a breakout SEE near a coronal hole region. We performed high-resolution 3D MHD numerical simulations with the Adaptively Refined MHD Solver (ARMS). Our results demonstrate that the model allows for the effective escape of energetic particles from deep within an ejecting well-defined plasmoid. We show how the complex interactions between the flare and breakout reconnection reproduce all the main observational features of SEEs and SEPs. We discuss the implications of our calculations for the upcoming Solar Orbiter and Solar Probe Plus missions, which will measure SEEs and SEPs near the Sun, thereby, mitigating propagation effects.This research was supported, in part, by the NASA SR&T and TR&T Programs.

  15. Electric fields and field-aligned currents in polar regions of the solar corona: 3-D MHD consideration

    NASA Technical Reports Server (NTRS)

    Pisanko, Yu. V.

    1995-01-01

    The calculation of the solar rotation electro-dynamical effects in the near-the-Sun solar wind seems more convenient from the non-inertial corotating reference frame. This implies some modification of the 3-D MHD equations generally on the base of the General Theory of Relativity. The paper deals with the search of stationary (in corotating non-inertial reference frame) solutions of the modified 3-D MHD equations for the in near-the-Sun high latitude sub-alfvenic solar wind. The solution is obtained requiring electric fields and field-aligned electric currents in the high latitude near-the-Sun solar wind. Various scenario are explored self-consistently via a number of numerical experiments. The analogy with the high latitude Earth's magnetosphere is used for the interpretation of the results. Possible observational manifestations are discussed.

  16. Flank solar wind interaction

    NASA Technical Reports Server (NTRS)

    Moses, Stewart L.; Greenstadt, Eugene W.

    1992-01-01

    This report summarizes the results of the first 12 months of our program to study the interaction of the Earth's magnetosphere with the solar wind on the far flanks of the bow shock. This study employs data from the ISEE-3 spacecraft during its traversals of the Earth's magnetotail and correlative data from spacecraft monitoring the solar wind upstream. Our main effort to date has involved assembling data sets and developing new plotting programs. Two talks were given at the Spring Meeting of the American Geophysical Union describing our initial results from analyzing data from the far flank foreshock and magnetosheath. The following sections summarize our results.

  17. 3D printing meets computational astrophysics: deciphering the structure of η Carinae's inner colliding winds

    NASA Astrophysics Data System (ADS)

    Madura, T. I.; Clementel, N.; Gull, T. R.; Kruip, C. J. H.; Paardekooper, J.-P.

    2015-06-01

    We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (≳120 M⊙), highly eccentric (e ˜ 0.9) binary star system η Carinae. We demonstrate the methodology used to incorporate 3D interactive figures into a PDF (Portable Document Format) journal publication and the benefits of using 3D visualization and 3D printing as tools to analyse data from multidimensional numerical simulations. Using a consumer-grade 3D printer (MakerBot Replicator 2X), we successfully printed 3D smoothed particle hydrodynamics simulations of η Carinae's inner (r ˜ 110 au) wind-wind collision interface at multiple orbital phases. The 3D prints and visualizations reveal important, previously unknown `finger-like' structures at orbital phases shortly after periastron (φ ˜ 1.045) that protrude radially outwards from the spiral wind-wind collision region. We speculate that these fingers are related to instabilities (e.g. thin-shell, Rayleigh-Taylor) that arise at the interface between the radiatively cooled layer of dense post-shock primary-star wind and the fast (3000 km s-1), adiabatic post-shock companion-star wind. The success of our work and easy identification of previously unrecognized physical features highlight the important role 3D printing and interactive graphics can play in the visualization and understanding of complex 3D time-dependent numerical simulations of astrophysical phenomena.

  18. 3D-PTV around Operational Wind Turbines

    NASA Astrophysics Data System (ADS)

    Brownstein, Ian; Dabiri, John

    2016-11-01

    Laboratory studies and numerical simulations of wind turbines are typically constrained in how they can inform operational turbine behavior. Laboratory experiments are usually unable to match both pertinent parameters of full-scale wind turbines, the Reynolds number (Re) and tip speed ratio, using scaled-down models. Additionally, numerical simulations of the flow around wind turbines are constrained by the large domain size and high Re that need to be simulated. When these simulations are preformed, turbine geometry is typically simplified resulting in flow structures near the rotor not being well resolved. In order to bypass these limitations, a quantitative flow visualization method was developed to take in situ measurements of the flow around wind turbines at the Field Laboratory for Optimized Wind Energy (FLOWE) in Lancaster, CA. The apparatus constructed was able to seed an approximately 9m x 9m x 5m volume in the wake of the turbine using artificial snow. Quantitative measurements were obtained by tracking the evolution of the artificial snow using a four camera setup. The methodology for calibrating and collecting data, as well as preliminary results detailing the flow around a 2kW vertical-axis wind turbine (VAWT), will be presented.

  19. Wind Turbine Wake Characterization from Temporally Disjunct 3-D Measurements

    SciTech Connect

    Doubrawa, Paula; Barthelmie, Rebecca J.; Wang, Hui; Pryor, S. C.; Churchfield, Matthew

    2016-11-01

    Scanning LiDARs can be used to obtain three-dimensional wind measurements in and beyond the atmospheric surface layer. In this work, metrics characterizing wind turbine wakes are derived from LiDAR observations and from large-eddy simulation (LES) data, which are used to recreate the LiDAR scanning geometry. The metrics are calculated for two-dimensional planes in the vertical and cross-stream directions at discrete distances downstream of a turbine under single-wake conditions. The simulation data are used to estimate the uncertainty when mean wake characteristics are quantified from scanning LiDAR measurements, which are temporally disjunct due to the time that the instrument takes to probe a large volume of air. Based on LES output, we determine that wind speeds sampled with the synthetic LiDAR are within 10% of the actual mean values and that the disjunct nature of the scan does not compromise the spatial variation of wind speeds within the planes. We propose scanning geometry density and coverage indices, which quantify the spatial distribution of the sampled points in the area of interest and are valuable to design LiDAR measurement campaigns for wake characterization. We find that scanning geometry coverage is important for estimates of the wake center, orientation and length scales, while density is more important when seeking to characterize the velocity deficit distribution.

  20. Wind turbine wake characterization from temporally disjunct 3-D measurements

    SciTech Connect

    Doubrawa, Paula; Barthelmie, Rebecca J.; Wang, Hui; Pryor, S. C.; Churchfield, Matthew

    2016-11-10

    Scanning LiDARs can be used to obtain three-dimensional wind measurements in and beyond the atmospheric surface layer. In this work, metrics characterizing wind turbine wakes are derived from LiDAR observations and from large-eddy simulation (LES) data, which are used to recreate the LiDAR scanning geometry. The metrics are calculated for two-dimensional planes in the vertical and cross-stream directions at discrete distances downstream of a turbine under single-wake conditions. The simulation data are used to estimate the uncertainty when mean wake characteristics are quantified from scanning LiDAR measurements, which are temporally disjunct due to the time that the instrument takes to probe a large volume of air. Based on LES output, we determine that wind speeds sampled with the synthetic LiDAR are within 10% of the actual mean values and that the disjunct nature of the scan does not compromise the spatial variation of wind speeds within the planes. We propose scanning geometry density and coverage indices, which quantify the spatial distribution of the sampled points in the area of interest and are valuable to design LiDAR measurement campaigns for wake characterization. Lastly, we find that scanning geometry coverage is important for estimates of the wake center, orientation and length scales, while density is more important when seeking to characterize the velocity deficit distribution.

  1. Wind turbine wake characterization from temporally disjunct 3-D measurements

    DOE PAGES

    Doubrawa, Paula; Barthelmie, Rebecca J.; Wang, Hui; ...

    2016-11-10

    Scanning LiDARs can be used to obtain three-dimensional wind measurements in and beyond the atmospheric surface layer. In this work, metrics characterizing wind turbine wakes are derived from LiDAR observations and from large-eddy simulation (LES) data, which are used to recreate the LiDAR scanning geometry. The metrics are calculated for two-dimensional planes in the vertical and cross-stream directions at discrete distances downstream of a turbine under single-wake conditions. The simulation data are used to estimate the uncertainty when mean wake characteristics are quantified from scanning LiDAR measurements, which are temporally disjunct due to the time that the instrument takes tomore » probe a large volume of air. Based on LES output, we determine that wind speeds sampled with the synthetic LiDAR are within 10% of the actual mean values and that the disjunct nature of the scan does not compromise the spatial variation of wind speeds within the planes. We propose scanning geometry density and coverage indices, which quantify the spatial distribution of the sampled points in the area of interest and are valuable to design LiDAR measurement campaigns for wake characterization. Lastly, we find that scanning geometry coverage is important for estimates of the wake center, orientation and length scales, while density is more important when seeking to characterize the velocity deficit distribution.« less

  2. Slow Solar Wind: Observations and Modeling

    NASA Astrophysics Data System (ADS)

    Abbo, L.; Ofman, L.; Antiochos, S. K.; Hansteen, V. H.; Harra, L.; Ko, Y.-K.; Lapenta, G.; Li, B.; Riley, P.; Strachan, L.; von Steiger, R.; Wang, Y.-M.

    2016-11-01

    While it is certain that the fast solar wind originates from coronal holes, where and how the slow solar wind (SSW) is formed remains an outstanding question in solar physics even in the post-SOHO era. The quest for the SSW origin forms a major objective for the planned future missions such as the Solar Orbiter and Solar Probe Plus. Nonetheless, results from spacecraft data, combined with theoretical modeling, have helped to investigate many aspects of the SSW. Fundamental physical properties of the coronal plasma have been derived from spectroscopic and imaging remote-sensing data and in situ data, and these results have provided crucial insights for a deeper understanding of the origin and acceleration of the SSW. Advanced models of the SSW in coronal streamers and other structures have been developed using 3D MHD and multi-fluid equations.

  3. Composition of the Solar Wind

    NASA Technical Reports Server (NTRS)

    Suess, S. T.

    2007-01-01

    The solar wind reflects the composition of the Sun and physical processes in the corona. Analysis produces information on how the solar system was formed and on physical processes in the corona. The analysis can also produce information on the local interstellar medium, galactic evolution, comets in the solar wind, dust in the heliosphere, and matter escaping from planets.

  4. Turbulent Transport in a Three-dimensional Solar Wind

    NASA Astrophysics Data System (ADS)

    Shiota, D.; Zank, G. P.; Adhikari, L.; Hunana, P.; Telloni, D.; Bruno, R.

    2017-03-01

    Turbulence in the solar wind can play essential roles in the heating of coronal and solar wind plasma and the acceleration of the solar wind and energetic particles. Turbulence sources are not well understood and thought to be partly enhanced by interaction with the large-scale inhomogeneity of the solar wind and the interplanetary magnetic field and/or transported from the solar corona. To investigate the interaction with background inhomogeneity and the turbulence sources, we have developed a new 3D MHD model that includes the transport and dissipation of turbulence using the theoretical model of Zank et al. We solve for the temporal and spatial evolution of three moments or variables, the energy in the forward and backward fluctuating modes and the residual energy and their three corresponding correlation lengths. The transport model is coupled to our 3D model of the inhomogeneous solar wind. We present results of the coupled solar wind-turbulence model assuming a simple tilted dipole magnetic configuration that mimics solar minimum conditions, together with several comparative intermediate cases. By considering eight possible solar wind and turbulence source configurations, we show that the large-scale solar wind and IMF inhomogeneity and the strength of the turbulence sources significantly affect the distribution of turbulence in the heliosphere within 6 au. We compare the predicted turbulence distribution results from a complete solar minimum model with in situ measurements made by the Helios and Ulysses spacecraft, finding that the synthetic profiles of the turbulence intensities show reasonable agreement with observations.

  5. Personal overview of solar wind 6

    SciTech Connect

    Gosling, J.T.

    1987-01-01

    The author reviews papers presented at the Solar Wind 6 Proceedings. The particular topics discussed are solar wind acceleration theory, heliosphere production of solar winds, coronal mass ejections, interplanetary shock disturbance, and solar wind ionic composition. A concern for the steady decline in solar wind observations is expressed. (LSP)

  6. ISM abundances and history: a 3D, solar neighborhood view

    NASA Astrophysics Data System (ADS)

    Lallement, R.; Vergely, J.-L.; Puspitarini, L.

    For observational reasons, the solar neighborhood is particularly suitable for the study of the multi-phase interstellar (IS) medium and the search for traces of its temporal evolution. On the other hand, by a number of aspects it seems to be a peculiar region. We use recent 3D maps of the IS dust based on color excess data as well as former maps of the gas to illustrate how such maps can be used to shed additional light on the specificity of the local medium, its history and abundance pattern. 3D maps reveal a gigantic cavity located in the third quadrant and connected to the Local Bubble, the latter itself running into an elongated cavity toward l≃ 70°. Most nearby cloud complexes of the so-called Gould belt but also more distant clouds seem to border a large fraction of this entire structure. The IS medium with the large cavity appears ionized and dust-poor, as deduced from ionized calcium and neutral sodium to dust ratios. The geometry favors the proposed scenario of Gould belt-Local Arm formation through the braking of a supercloud by interaction with a spiral density wave \\citep{olano01}. The highly variable D/H ratio in the nearby IS gas may also be spatially related to the global structure. We speculate about potential consequences of the supercloud encounter and dust-gas decoupling during its braking, in particular the formation of strong inhomogeneities in both the dust to gas abundance ratio and the dust characteristics: (i) during the ≃ 500 Myrs prior to the collision, dust within the supercloud may have been gradually, strongly enriched in D due to an absence of strong stellar formation and preferential adsorption of D \\citep{jura82,draine03} ; (ii) during its interaction with the Plane and the braking dust-rich and dust-poor regions may have formed due to differential gas drag, the dust being more concentrated in the dense areas; strong radiation pressure from OB associations at the boundary of the left-behind giant cavity may have also helped

  7. Corona and solar wind

    NASA Technical Reports Server (NTRS)

    Withbroe, G. L.

    1986-01-01

    The Pinhole/Occulter Facility is a powerful tool for studying the physics of the extended corona and origins of the solar wind. Spectroscopic data acquired by the P/OF coronal instruments can greatly expand empirical information about temperatures, densities, flow velocities, magnetic fields, and chemical abundances in the corona out to r or approx. 10 solar radii. Such information is needed to provide tight empirical constraints on critical physical processes involved in the transport and dissipation of energy and momentum, the heating and acceleration of plasma, and the acceleration of energetic particles. Because of its high sensitivity, high spatial and temporal resolutions, and powerful capabilities for plasma diagnostics, P/OF can significantly increase our empirical knowledge about coronal streamers and transients and thereby advance the understanding of the physics of these phenomena. P/OF observations can be used to establish the role in solar wind generation, if any, of small-scale dynamical phenomena, such as spicules, macrospicules and coronal bullets, and the role of the fine-scale structures, such as polar plumes. Finally, simultaneous measurements by the P/OF coronal and hard X-ray instruments can provide critical empirical information concerning nonthermal energy releases and acceleration of energetic particles in the corona.

  8. 3D hydrodynamical and radiative transfer modeling of η Carinae's colliding winds

    NASA Astrophysics Data System (ADS)

    Madura, T. I.; Clementel, N.; Gull, T. R.; Kruip, C. J. H.; Paardekooper, J.-P.; Icke, V.

    We present results of full 3D hydrodynamical and radiative transfer simulations of the colliding stellar winds in the massive binary system η Carinae. We accomplish this by applying the SimpleX algorithm for 3D radiative transfer on an unstructured Voronoi-Delaunay grid to recent 3D smoothed particle hydrodynamics (SPH) simulations of the binary colliding winds. We use SimpleX to obtain detailed ionization fractions of hydrogen and helium, in 3D, at the resolution of the original SPH simulations. We investigate several computational domain sizes and Luminous Blue Variable primary star mass-loss rates. We furthermore present new methods of visualizing and interacting with output from complex 3D numerical simulations, including 3D interactive graphics and 3D printing. While we initially focus on η Car, the methods employed can be applied to numerous other colliding wind (WR 140, WR 137, WR 19) and dusty `pinwheel' (WR 104, WR 98a) binary systems. Coupled with 3D hydrodynamical simulations, SimpleX simulations have the potential to help determine the regions where various observed time-variable emission and absorption lines form in these unique objects.

  9. Venus: Interaction with Solar Wind

    NASA Astrophysics Data System (ADS)

    Russell, C.; Luhmann, J.; Murdin, P.

    2002-07-01

    The solar wind interaction with VENUS provides the archetypal interaction of a flowing magnetized PLASMA with a PLANETARY IONOSPHERE. Mars interacts with the solar wind in much the same way as does Venus, while the rotating plasma in the Saturnian magnetosphere is believed to interact similarly with its moon, Titan (see SATURN: MAGNETOSPHERE INTERACTION WITH TITAN). The interaction of the Jovian ...

  10. 3D Hydrodynamical and Radiative Transfer Modeling of Eta Carinae's Colliding Winds

    NASA Astrophysics Data System (ADS)

    Madura, Thomas Ignatius; Clementel, Nicola; Gull, Theodore R.; Kruip, Chael J. H.; Paardekooper, Jan-Pieter; Icke, Vincent

    2015-08-01

    We present the results of full 3D hydrodynamical and radiative transfer simulations of the colliding stellar winds in the massive binary system Eta Carinae (Clementel, Madura, et al. 2014, MNRAS, 443, 2475 and Clementel, Madura, et al. 2015, MNRAS, 447, 2445). We accomplish this by applying the SimpleX algorithm for 3D radiative transfer on an unstructured Voronoi-Delaunay grid to 3D smoothed particle hydrodynamics simulations of the binary colliding winds. We use SimpleX to obtain detailed ionization fractions of hydrogen and helium in 3D. We investigate several computational domain sizes and Luminous Blue Variable primary-star mass-loss rates. We show how the SimpleX simulations can be used to generate synthetic spectral data cubes for comparison to data obtained with the Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph as part of a multi-cycle program to map changes in Eta Carinae's spatially extended interacting wind structures across one binary cycle. Comparison of the HST observations to the SimpleX models can help lead to more accurate constraints on the orbital, stellar, and wind parameters of the Eta Carinae system, such as the LBV primary's mass-loss rate and the companion star's temperature and luminosity. We furthermore present new methods of visualizing and interacting with output from complex 3D numerical simulations, including 3D interactive graphics and 3D printing (Madura et al. 2015, arXiv:1503.00716). While we initially focus specifically on Eta Carinae, the methods employed can be applied to numerous other colliding wind (WR 140, WR 137, WR 19) and dusty ‘pinwheel’ (WR 112, WR 104, WR 98a) binary systems. Coupled with 3D hydrodynamical simulations, SimpleX simulations have the potential to help determine the regions where dust can form and survive in these unique objects.

  11. Solar wind photoplate study

    NASA Technical Reports Server (NTRS)

    Scott, B. W.; Voorhies, H. G.

    1972-01-01

    An ion sensitive emulsion detection system has been considered for use in a cycloidal focusing mass spectrometer to measure the various atomic species which comprise the solar plasma. The responses of Ilford Q2 and Kodak SC7 emulsions were measured with N(+) ions at 6 keV to 10 keV, He(++) ions at 750 eV to 2500 eV, and H(+) ions at 550 eV to 1400 eV. These ions have the approximate range of velocities (about 300-500 km/sec) encountered in the solar wind. The work was carried out on a specially prepared magnetic sector mass analyzer. Characteristic response curves were generated, each one utilizing approximately 50 data points at three or more current densities. In addition to the ion response, measurements of the response of these emulsions to a photon flux simulating the visible portion of the solar spectrum were made. The results obtained will be presented in detail and interpreted in relation to other data available for these emulsions.

  12. 3D Printing Meets Computational Astrophysics: Deciphering the Structure of Eta Carinae’s Colliding Winds Using 3D Prints of Smoothed Particle Hydrodynamics Simulations

    NASA Astrophysics Data System (ADS)

    Madura, Thomas; Gull, Theodore R.; Clementel, Nicola; Paardekooper, Jan-Pieter; Kruip, Chael; Corcoran, Michael F.; Hamaguchi, Kenji; Teodoro, Mairan

    2015-01-01

    We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (>120 MSun), highly eccentric (e ~ 0.9) binary Eta Carinae. Using a consumer-grade 3D printer (Makerbot Replicator 2X), we successfully printed 3D smoothed particle hydrodynamics simulations of Eta Carinae's inner (r ~110 AU) wind-wind collision interface at multiple orbital phases. These 3D prints reveal important, previously unknown 'finger-like' structures at orbital phases shortly after periastron (φ ~1.045) that protrude radially outward from the spiral wind-wind collision region. We speculate that these fingers are related to instabilities (e.g. Rayleigh-Taylor) that arise at the interface between the radiatively-cooled layer of dense post-shock primary-star wind and the hot, adiabatic post-shock companion-star wind. The success of our work and easy identification of previously unknown physical features highlight the important role 3D printing can play in the visualization and understanding of complex 3D time-dependent numerical simulations of astrophysical phenomena.

  13. Forecasting Solar Wind Speeds

    NASA Astrophysics Data System (ADS)

    Suzuki, Takeru K.

    2006-03-01

    By explicitly taking into account the effects of Alfvén waves, I derive from a simple energetics argument a fundamental relation that predicts solar wind (SW) speeds in the vicinity of Earth from physical properties on the Sun. Kojima et al. recently found from observations that the ratio of surface magnetic field strength to the expansion factor of open magnetic flux tubes is a good indicator of the SW speed. I show by using the derived relation that this nice correlation is evidence of Alfvén wave acceleration of the SW in expanding flux tubes. The observations further require that the fluctuation amplitudes of magnetic field lines at the surface be almost universal in different coronal holes, which needs to be tested with future observations.

  14. The performance & flow visualization studies of three-dimensional (3-D) wind turbine blade models

    NASA Astrophysics Data System (ADS)

    Sutrisno, Prajitno, Purnomo, W., Setyawan B.

    2016-06-01

    Recently, studies on the design of 3-D wind turbine blades have a less attention even though 3-D blade products are widely sold. In contrary, advanced studies in 3-D helicopter blade tip have been studied rigorously. Studies in wind turbine blade modeling are mostly assumed that blade spanwise sections behave as independent two-dimensional airfoils, implying that there is no exchange of momentum in the spanwise direction. Moreover, flow visualization experiments are infrequently conducted. Therefore, a modeling study of wind turbine blade with visualization experiment is needed to be improved to obtain a better understanding. The purpose of this study is to investigate the performance of 3-D wind turbine blade models with backward-forward swept and verify the flow patterns using flow visualization. In this research, the blade models are constructed based on the twist and chord distributions following Schmitz's formula. Forward and backward swept are added to the rotating blades. Based on this, the additional swept would enhance or diminish outward flow disturbance or stall development propagation on the spanwise blade surfaces to give better blade design. Some combinations, i. e., b lades with backward swept, provide a better 3-D favorable rotational force of the rotor system. The performance of the 3-D wind turbine system model is measured by a torque meter, employing Prony's braking system. Furthermore, the 3-D flow patterns around the rotating blade models are investigated by applying "tuft-visualization technique", to study the appearance of laminar, separated, and boundary layer flow patterns surrounding the 3-dimentional blade system.

  15. Wind and solar powered turbine

    NASA Technical Reports Server (NTRS)

    Wells, I. D.; Koh, J. L.; Holmes, M. (Inventor)

    1984-01-01

    A power generating station having a generator driven by solar heat assisted ambient wind is described. A first plurality of radially extendng air passages direct ambient wind to a radial flow wind turbine disposed in a centrally located opening in a substantially disc-shaped structure. A solar radiation collecting surface having black bodies is disposed above the fist plurality of air passages and in communication with a second plurality of radial air passages. A cover plate enclosing the second plurality of radial air passages is transparent so as to permit solar radiation to effectively reach the black bodies. The second plurality of air passages direct ambient wind and thermal updrafts generated by the black bodies to an axial flow turbine. The rotating shaft of the turbines drive the generator. The solar and wind drien power generating system operates in electrical cogeneration mode with a fuel powered prime mover.

  16. Fast and slow radiation-driven wind solutions using ZEUS-3D

    NASA Astrophysics Data System (ADS)

    Araya, I.; Curé, M.; ud-Doula, A.; Santillán, A.

    2014-10-01

    Currently, the theory of radiation-driven winds of massive stars possess three known solutions for the velocity and density profiles of the stellar winds, namely: the fast, Ω -slow and δ -slow solutions. In order to confirm their stability we use a time-dependent numerical hydrodynamic code called ZEUS-3D, and then we compare their results with the stationary solutions from our numerical hydrodynamic code. ZEUS-3D needs an initial trial solution to start to integrate, for this we use the stationary solution (from our code) or a β-law for the velocity field. In both cases we obtain the same results. Fast and both slow stationary solutions are attained in ZEUS-3D and are all stable. Furthermore, there is a very good agreement with the velocity and density fields from ZEUS-3D and our code, having differences between the terminal velocities lower than 3%. In addition, we found that ZEUS-3D is very sensitive to the boundary conditions (base density and velocity profile), in some cases we obtain kinks in the velocity profiles, similar to the ones obtained by Madura et al. (2007) for stars with high rotation. Such kinks are most likely the result of the wind being mass overloaded, but further investigation is needed to understand its nature better. Currently, we are exploring the effects of small perturbation at the base of the wind in order to study possible transitions or oscillations between δ-slow and fast solutions.

  17. Vertical profiles of the 3-D wind velocity retrieved from multiple wind lidars performing triple range-height-indicator scans

    DOE PAGES

    Debnath, Mithu; Iungo, G. Valerio; Ashton, Ryan; ...

    2017-02-06

    Vertical profiles of 3-D wind velocity are retrieved from triple range-height-indicator (RHI) scans performed with multiple simultaneous scanning Doppler wind lidars. This test is part of the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) campaign carried out at the Boulder Atmospheric Observatory. The three wind velocity components are retrieved and then compared with the data acquired through various profiling wind lidars and high-frequency wind data obtained from sonic anemometers installed on a 300 m meteorological tower. The results show that the magnitude of the horizontal wind velocity and the wind direction obtained from the triple RHI scans are generally retrieved with goodmore » accuracy. However, poor accuracy is obtained for the evaluation of the vertical velocity, which is mainly due to its typically smaller magnitude and to the error propagation connected with the data retrieval procedure and accuracy in the experimental setup.« less

  18. Vertical profiles of the 3-D wind velocity retrieved from multiple wind lidars performing triple range-height-indicator scans

    SciTech Connect

    Debnath, Mithu; Iungo, G. Valerio; Ashton, Ryan; Brewer, W. Alan; Choukulkar, Aditya; Delgado, Ruben; Lundquist, Julie K.; Shaw, William J.; Wilczak, James M.; Wolfe, Daniel

    2017-01-01

    Vertical profiles of 3-D wind velocity are retrieved from triple range-height-indicator (RHI) scans performed with multiple simultaneous scanning Doppler wind lidars. This test is part of the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) campaign carried out at the Boulder Atmospheric Observatory. The three wind velocity components are retrieved and then compared with the data acquired through various profiling wind lidars and high-frequency wind data obtained from sonic anemometers installed on a 300 m meteorological tower. The results show that the magnitude of the horizontal wind velocity and the wind direction obtained from the triple RHI scans are generally retrieved with good accuracy. However, poor accuracy is obtained for the evaluation of the vertical velocity, which is mainly due to its typically smaller magnitude and to the error propagation connected with the data retrieval procedure and accuracy in the experimental setup.

  19. Vertical profiles of the 3-D wind velocity retrieved from multiple wind lidars performing triple range-height-indicator scans

    NASA Astrophysics Data System (ADS)

    Debnath, Mithu; Valerio Iungo, G.; Ashton, Ryan; Brewer, W. Alan; Choukulkar, Aditya; Delgado, Ruben; Lundquist, Julie K.; Shaw, William J.; Wilczak, James M.; Wolfe, Daniel

    2017-02-01

    Vertical profiles of 3-D wind velocity are retrieved from triple range-height-indicator (RHI) scans performed with multiple simultaneous scanning Doppler wind lidars. This test is part of the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) campaign carried out at the Boulder Atmospheric Observatory. The three wind velocity components are retrieved and then compared with the data acquired through various profiling wind lidars and high-frequency wind data obtained from sonic anemometers installed on a 300 m meteorological tower. The results show that the magnitude of the horizontal wind velocity and the wind direction obtained from the triple RHI scans are generally retrieved with good accuracy. However, poor accuracy is obtained for the evaluation of the vertical velocity, which is mainly due to its typically smaller magnitude and to the error propagation connected with the data retrieval procedure and accuracy in the experimental setup.

  20. Anisotropy of solar wind fluctuations: fast wind vs slow wind.

    NASA Astrophysics Data System (ADS)

    Dasso, S.; Milano, L. J.; Matthaeus, W. H.; Smith, C. W.

    2004-12-01

    The fluctuations in the solar wind are often modeled in terms of two distinct populations: (a) a 'wave-like' population with quasi-parallel wavenumbers and (b) a quasi-two dimensional 'turbulent-like' fluctuations with perpendicular wavenumbers. Here the qualification "quasi-parallel" or "quasi-2D" means that nearby wavevectors are grouped together in an idealzed way, for simplicity. The relative abundance of these two populations is important in gaining insight on the dynamics of waves or turbulence in the solar wind, and also in understanding the transport of energetic particle populations, as turbulence geometry has a major impact on scattering. It has been established in the literature that turbulence is, generally speaking, more developed in the slow solar wind, with power spectra closer to the kolmogorov value at 1AU, while the fast solar wind is more "Alfvenic", typically with higher values of the cross helicity. It seems natural therefore to investigate the anisotropy structure of solar wind fluctuations as a function of wind speed. We present here our preliminary results in this regard, obtained from magnetic and plasma data from the ACE specraft, at 1AU, essentially in the ecliptic plane. We also discuss possible implications for the modeling the evolution of waves and turbulence in the solar wind.

  1. Solar wind acceleration in the solar corona

    NASA Technical Reports Server (NTRS)

    Giordano, S.; Antonucci, E.; Benna, C.; Kohl, J. L.; Noci, G.; Michels, J.; Fineschi, S.

    1997-01-01

    The intensity ratio of the O VI doublet in the extended area is analyzed. The O VI intensity data were obtained with the ultraviolet coronagraph spectrometer (UVCS) during the SOHO campaign 'whole sun month'. The long term observations above the north pole of the sun were used for the polar coronal data. Using these measurements, the solar wind outflow velocity in the extended corona was determined. The 100 km/s level is running along the streamer borders. The acceleration of the solar wind is found to be high in regions between streamers. In the central part of streamers, the outflow velocity of the coronal plasma remains below 100 km/s at least within 3.8 solar radii. The regions at the north and south poles, characterized by a more rapid acceleration of the solar wind, correspond to regions where the UVCS observes enhanced O VI line broadenings.

  2. Highly Alfvenic Slow Solar Wind

    NASA Technical Reports Server (NTRS)

    Roberts, D. Aaron

    2010-01-01

    It is commonly thought that fast solar wind tends to be highly Alfvenic, with strong correlations between velocity and magnetic fluctuations, but examples have been known for over 20 years in which slow wind is both Alfvenic and has many other properties more typically expected of fast solar wind. This paper will present a search for examples of such flows from more recent data, and will begin to characterize the general characteristics of them. A very preliminary search suggests that such intervals are more common in the rising phase of the solar cycle. These intervals are important for providing constraints on models of solar wind acceleration, and in particular the role waves might or might not play in that process.

  3. A 3-D aerodynamic method for the analysis of isolated horizontal-axis wind turbines

    SciTech Connect

    Ammara, I.; Masson, C.; Paraschivoiu, I.

    1997-12-31

    In most existing performance-analysis methods, wind turbines are considered isolated so that interference effects caused by other rotors or by the site topography are neglected. The main objective of this paper is to propose a practical 3-D method suitable for the study of these effects, in order to optimize the arrangement and the positioning of Horizontal-Axis Wind Turbines (HAWTs) in a wind farm. In the proposed methodology, the flow field around isolated HAWTs is predicted by solving the 3-D, time-averaged, steady-state, incompressible, Navier-Stokes equations in which the turbines are represented by distributions of momentum sources. The resulting governing equations are solved using a Control-Volume Finite Element Method (CVFEM). The fundamental aspects related to the development of a practical 3-D method are discussed in this paper, with an emphasis on some of the challenges that arose during its implementation. The current implementation is limited to the analysis of isolated HAWTs. Preliminary results have indicated that, the proposed 3-D method reaches the same level of accuracy, in terms of performance predictions, that the previously developed 2-D axisymmetric model and the well-known momentum-strip theory, while still using reasonable computers resources. It can be considered as a useful tool for the design of HAWTs. Its main advantages, however, are its intrinsic capacity to predict the details of the flow in the wake, and its capabilities of modelling arbitrary wind-turbine arrangements and including ground effects.

  4. Validation of US3D for Capsule Aerodynamics using 05-CA Wind Tunnel Test Data

    NASA Technical Reports Server (NTRS)

    Schwing, Alan

    2012-01-01

    Several comparisons of computational fluid dynamics to wind tunnel test data are shown for the purpose of code validation. The wind tunnel test, 05-CA, uses a 7.66% model of NASA's Multi-Purpose Crew Vehicle in the 11-foot test section of the Ames Unitary Plan Wind tunnel. A variety of freestream conditions over four Mach numbers and three angles of attack are considered. Test data comparisons include time-averaged integrated forces and moments, time-averaged static pressure ports on the surface, and Strouhal Number. The applicability of the US3D code to subsonic and transonic flow over a bluff body is assessed on a comprehensive data set. With close comparison, this work validates US3D for highly separated flows similar to those examined here.

  5. Imaging solar coronal magnetic structures in 3D

    NASA Astrophysics Data System (ADS)

    Cartledge, N. P.

    The study of solar coronal structures and, in particular prominences, is a key part of understanding the highly complex physical mechanisms occurring in the Sun's atmosphere. Solar prominences are important in their own right and some of the most puzzling questions in solar theory have arisen through their study. For example, how do they form and how is their mass continuously replenished? How can the magnetic field provide their continuous support against gravity over time periods of several months? How can such cool, dense material exist in thermal equilibrium in the surrounding coronal environment? Why do they erupt? A study of their structure and that of the surrounding medium is important in determining the nature of the coronal plasma and magnetic field. Also, prominences are closely associated with other key phenomena such as coronal mass ejections and eruptive solar flares which occur as a prominence loses equilibrium and rises from the solar surface. Our current understanding of these fascinating structures is extremely limited and we know very little about their basic global structure. In fact, recent prominence observations have caused our basic paradigms to be challenged (Priest, 1996) and so we must set up new models in order to gain even a fundamental understanding. Prominences are highly nonlinear, three-dimensional structures. Large feet (or barbs) reach out from the main body of a prominence and reach down to the photosphere where the dense material continuously drains away. These provide a real clue to the three-dimensional nature of the coronal field and its relation to the photospheric field. It is important, therefore, to make stereographic observations of prominences in order to gain a basic understanding of their essentially three-dimensional nature and attempt to formulate new paradigms for their structure and evolution. There is no doubt that the study of prominences in three dimensions is a crucial exercise if we are to develop a better

  6. Wind in the Solar System

    ERIC Educational Resources Information Center

    McIntosh, Gordon

    2010-01-01

    As an astronomy instructor I am always looking for commonly experienced Earthly phenomena to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote short "TPT" articles on frost and precipitation. The present article is on winds in the solar system. A windy day or storm might…

  7. 3D augmented reality for improving social acceptance and public participation in wind farms planning

    NASA Astrophysics Data System (ADS)

    Grassi, S.; Klein, T. M.

    2016-09-01

    Wind energy is one of the most important source of renewable energy characterized by a significant growth in the last decades and giving a more and more relevant contribution to the energy supply. One of the main disadvantages of a faster integration of wind energy into the energy mix is related to the visual impact of wind turbines on the landscape. In addition, the siting of new massive infrastructures has the potential to threaten a community's well-being if new projects are perceived being unfair. The public perception of the impact of wind turbines on the landscape is also crucial for their acceptance. The implementation of wind energy projects is hampered often because of a lack of planning or communication tools enabling a more transparent and efficient interaction between all stakeholders involved in the projects (i.e. developers, local communities and administrations, NGOs, etc.). Concerning the visual assessment of wind farms, a critical gap lies in effective visualization tools to improve the public perception of alternative wind turbines layouts. In this paper, we describe the advantages of a 3D dynamical and interactive visualization platform for an augmented reality to support wind energy planners in order to enhance the social acceptance of new wind energy projects.

  8. Solar wind precipitation on Mars

    NASA Astrophysics Data System (ADS)

    Stenberg, G.; Dieval, C.; Nilsson, H.; Kallio, E.; Barabash, S.; Futaana, Y.; Shematovich, V.; Bisikalo, D.

    2011-10-01

    We have found that solar wind particles frequently precipitate onto the atmosphere of Mars [1,2]. The precipitating particles contribute to the energy and matter flux into the ionosphere. We use ion data from the ASPERA-3 instrument onboard Mars Express to investigate the precipitation patterns, processes and the total transfer of energy and matter from the solar wind to the atmosphere. The main reason for the proton and alpha particle precipitation is likely the large gyroradii of hot particles compared to the size of the induced magnetosphere/magnetic barrier. We find that the particle penetration depends on the direction of the convection electric field in the solar wind but that the crustal magnetic fields have very little influence. The total energy flux is low compared to the solar radiation heating on the dayside, but a significant energy source on the nightside. We also believe that the solar wind alphaparticles precipitating into the atmosphere is an important source of the neutral helium in the Martian atmosphere. We combine our observations with computer modeling [3,4]. We have applied a Direct Simulation Monte Carlo method to solve the kinetic equation for the H/H+ transport in the upper Martian atmosphere including CO2, N2 and O. We conclude that the induced magnetic field around Mars plays the crucial role in the transport of charged particles in the upper atmosphere, and it determines the energy deposition of the solar wind.

  9. Effects of the LBV Primary's Mass-loss Rate on the 3D Hydrodynamics of eta Carinae's Colliding Winds

    NASA Technical Reports Server (NTRS)

    Madura, Thomas I.; Gull, Theodore R.; Cocoran, M.; Okazaki, A.; Owocki, S.; Russell, C.; Hamaguchi, K.; Clementel, N; Groh, J.; Hillier, D. J.

    2013-01-01

    At the heart of eta Carinae's spectacular "Homunculus" nebula lies an extremely luminous (L(sub Total) greater than approximately 5 × 10(exp 6) solar luminosity) colliding wind binary with a highly eccentric (e approximately 0.9), 5.54-year orbit (Figure 1). The primary of the system, a Luminous Blue Variable (LBV), is our closest (D approximately 2.3 kpc) and best example of a pre-hypernova or pre-gamma ray burst environment. The remarkably consistent and periodic RXTE X-ray light curve surprisingly showed a major change during the system's last periastron in 2009, with the X-ray minimum being approximately 50% shorter than the minima of the previous two cycles1. Between 1998 and 2011, the strengths of various broad stellar wind emission lines (e.g. Halpha, Fe II) in line-of-sight (l.o.s.) also decreased by factors of 1.5 - 3 relative to the continuum2. The current interpretation for these changes is that they are due to a gradual factor of 2 - 4 drop in the primary's mass-loss rate over the last approximately 15 years1, 2. However, while a secular change is seen for a direct view of the central source, little to no change is seen in profiles at high stellar latitudes or reflected off of the dense, circumbinary material known as the "Weigelt blobs"2, 3. Moreover, model spectra generated with CMFGEN predict that a factor of 2 - 4 drop in the primary's mass-loss rate should lead to huge changes in the observed spectrum, which thus far have not been seen. Here we present results from large- (plus or minus 1620 AU) and small- (plus or minus 162 AU) domain, full 3D smoothed particle hydrodynamics (SPH) simulations of eta Car's massive binary colliding winds for three different primary-star mass-loss rates (2.4, 4.8, and 8.5 × 10(exp -4) solar mass/yr). The goal is to investigate how the mass-loss rate affects the 3D geometry and dynamics of eta Car's optically-thick wind and spatially-extended wind-wind collision (WWC) regions, both of which are known sources of

  10. PHOTOIONIZATION IN THE SOLAR WIND

    SciTech Connect

    Landi, E.; Lepri, S. T.

    2015-10-20

    In this work we investigate the effects of photoionization on the charge state composition of the solar wind. Using measured solar EUV and X-ray irradiance, the Michigan Ionization Code and a model for the fast and slow solar wind, we calculate the evolution of the charge state distribution of He, C, N, O, Ne, Mg, Si, S, and Fe with and without including photoionization for both types of wind. We find that the solar radiation has significant effects on the charge state distribution of C, N, and O, causing the ionization levels of these elements to be higher than without photoionization; differences are largest for oxygen. The ions commonly observed for elements heavier than O are much less affected, except in ICMEs where Fe ions more ionized than 16+ can also be affected by the solar radiation. We also show that the commonly used O{sup 7+}/O{sup 6+} density ratio is the most sensitive to photoionization; this sensitivity also causes the value of this ratio to depend on the phase of the solar cycle. We show that the O{sup 7+}/O{sup 6+} ratio needs to be used with caution for solar wind classification and coronal temperature estimates, and recommend the C{sup 6+}/C{sup 4+} ratio for these purposes.

  11. Periodic solar wind density structures

    NASA Astrophysics Data System (ADS)

    Viall, Nicholeen Mary

    2010-01-01

    This dissertation addresses a specific aspect of the Sun-Earth connection: we show that coronal activity creates periodic density structures in the solar wind which convect radially outward and interact with Earth's magnetosphere. First, we analyze 11 years (1995-2005) of in situ solar wind density observations from the Wind spacecraft and find that periodic density structures occur at particular sets of radial length-scales more often than others. This indicates that these density fluctuations, which have radial length-scales of hundreds of megameters, cannot be attributed entirely to turbulence. Next, we analyze their effect on Earth's magnetosphere. Though these structures are not waves in the solar wind rest frame, they appear at discrete frequencies in Earth's reference frame. They compress the magnetosphere as they convect past, driving global magnetospheric oscillations at the same discrete frequencies as the periodic density structures. Last, we investigate source regions and mechanisms of the periodic solar wind density structures. We analyze the alpha particle to proton abundance ratio during events of periodic density structures. In many events, the proton and alpha density fluctuations are anti- correlated, which strongly argues for either temporally or spatially varying coronal source plasma. We examine white light images of the solar wind taken with SECCHI HI1 on the STEREO spacecraft and find periodic density structures as near to the Sun as 15 solar radii. The smallest resolvable periodic structures that we identify are of comparable length to those found at 1 AU, providing further evidence that at least some periodic density structures are generated in the solar corona as the solar wind is formed. Guided by the properties observed during previous studies and the characteristics established through the work presented here, we examine possible candidate mechanisms in the solar corona that can form periodic density structures. We conclude that

  12. Geoeffectiveness of Extreme Solar Winds

    NASA Astrophysics Data System (ADS)

    Alleyne, H.; Nanan, B.; Walker, S.; Reme, H.; Lucek, E.; Andre, M.; Cornilleau-Wehrlin, N.; Fazakerley, A.; Decreau, P.; McCrea, I.; Zhang, S.; van Eyken, A.

    2006-12-01

    The geoeffectiveness of the extreme solar winds that flowed pass the Earth on 24 October 2003, 07 November 2004 and 09 November 2004 are presented using Cluster (FGM, CIS, PEACE, STAFF and EFW) and ground- based (EISCAT radars at 69.6N, 19.2E and IMAGE magnetometer network at 68-79N)observations. The Cluster observations suggest that magnetic reconnection need not be the main process for solar wind entry into the magnetosphere during extreme solar winds. The ion velocity in the magnetosheath-cusp region remains strongly anti-sunward and poleward and ion density remains high irrespective of IMF Bz is negative or positive. The ion velocity components are also found to agree with the ExB velocities. The ground-based observations indicate that the extreme solar winds directly affect the high latitude ionosphere. The solar wind plasma is found to enter the ionosphere through an afternoon cusp that descends to low latitudes during negative IMF Bz period when a westward electrojet is also found to ascend to high latitudes.

  13. Recent US Activities Toward Development of a Global Tropospheric 3D Wind Profiling System

    NASA Astrophysics Data System (ADS)

    Gentry, B. M.; Atlas, R.; Baker, W.; Emmitt, G. D.; Hardesty, R. M.; Kakar, R. K.; Kavaya, M. J.; Mango, S.; Miller, K.; Riishojgaard, L. P.

    2008-12-01

    The wind field plays a unique dynamical role in forcing the mass field to adjust to it at all scales in the tropics, and at small scales in the extra-tropics. Because of this unique role, knowledge of the wind field is required to accurately specify the global initial conditions for numerical weather forecasting. In addition to improving numerical weather prediction, there is also a need for improved accuracy of wind fields to assess long term sensitivity of the general circulation to climate change and to improve horizontal and vertical transport estimates of important atmospheric constituents. In spite of the significance, the 3-D structure of the wind field remains largely unobserved on a global scale. A new satellite mission to accurately measure the global wind field would fill this important gap in the Global Observing System. Space-based Doppler wind lidar has been identified as the key technology necessary to meet the global wind profiling requirement. The 2007 NRC Decadal Survey for Earth Science lists a Global Tropospheric 3-D Wind mission as one of the 15 priority missions recommended for NASA in the next decade. The NRC survey recommended a two phase approach to achieving an operational global wind measurement capability. The first recommended step is for NASA to develop the technology and fly a pre-operational mission to demonstrate the technology and measurement concept and establish the performance standards for an operational wind mission. Phase two would be to develop and fly an operational wind system in the 2025 timeframe. The technology approach recommended is a hybrid Doppler wind lidar (HDWL). The HDWL takes advantage of the complementary capabilities of two Doppler lidar technologies, a coherent Doppler lidar sensing winds from the aerosol backscattered laser signal at a wavelength of 2 microns and a direct detection Doppler lidar sensing winds from the molecular backscattered laser signal at 355 nm. The direct detection Doppler system

  14. 3D Modeling of Forbidden Line Emission in the Binary Wind Interaction Region of Eta Carinae

    NASA Technical Reports Server (NTRS)

    Madura, Thomas; Gull, T. R.; Owocki, S.; Okazaki, A. T.; Russell, C. M. P.

    2010-01-01

    We present recent work using three-dimensional (3D) Smoothed Particle Hydrodynamics (SPH) simulations to model the high ([Fe III], [Ar III], [Ne III] and [S III]) and low ([Fe II], [Ni II]) ionization forbidden emission lines observed in Eta Carinae using the HST/STIS. These structures are interpreted as the time-averaged, outer extensions of the primary wind and the wind-wind interaction region directly excited by the FUV of the hot companion star of this massive binary system. We discuss how analyzing the results of the 3D SPH simulations and synthetic slit spectra and comparing them to the spectra obtained with the HST/STIS helps us determine the absolute orientation of the binary orbit and helps remove the degeneracy inherent to models based solely on the observed RXTE X-ray light curve. A key point of this work is that spatially resolved observations like those with HST/STIS and comparison to 3D models are necessary to determine the alignment or misalignment of the orbital angular momentum axis with the Homunculus, or correspondingly, the alignment of the orbital plane with the Homunculus skirt.

  15. Solar-wind velocity decreases

    NASA Astrophysics Data System (ADS)

    Geranios, A.

    1980-08-01

    A model is developed to account for the solar wind electron and proton temperature decreases observed following the passage of an interplanetary shock wave and during the velocity decrease of a solar wind stream. The equations of mass and energy conservation are solved for a fully ionized, electrically neutral plasma expanding radially and spherically symmetrically, taking into account the heat flux from the solor corona to the plasma along the open magnetic field lines, and the electron thermal conductivity. An analytical relationship between the temperature and the velocity of the solar wind plasma is obtained which is found to be in agreement with experimental measurements made by the Vela 5 and 6 and IMP 6 satellites from August 1969-May 1974. It is thus proposed that the observed low plasma temperatures are due to the fact that the temperature decrease of the expanding plasma exceeds the heat gain due to thermal conduction from the corona.

  16. 3D Radiative Transfer in Eta Carinae: Application of the SimpleX Algorithm to 3D SPH Simulations of Binary Colliding Winds

    NASA Technical Reports Server (NTRS)

    Clementel, N.; Madura, T. I.; Kruip, C.J.H.; Icke, V.; Gull, T. R.

    2014-01-01

    Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in eta Car. Observations of different broad high- and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in eta Car.We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidden emission lines can form. Including collisional ionization is necessary to achieve a better description of the ionization states, especially in the areas shielded from the secondary's radiation. We find that reducing the primary's mass-loss rate increases the volume of ionized gas, creating larger areas where the forbidden emission lines can form.We conclude that post processing 3D SPH data with SimpleX is a viable tool to create ionization maps for eta Car.

  17. 3D Radiative Transfer in Eta Carinae: Application of the SimpleX Algorithm to 3D SPH Simulations of Binary Colliding Winds

    NASA Technical Reports Server (NTRS)

    Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Icke, V.; Gull, T. R.

    2014-01-01

    Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in Eta Car. Observations of different broad high- and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in Eta Car. We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidden emission lines can form. Including collisional ionization is necessary to achieve a better description of the ionization states, especially in the areas shielded from the secondary's radiation. We find that reducing the primary's mass-loss rate increases the volume of ionized gas, creating larger areas where the forbidden emission lines can form. We conclude that post processing 3D SPH data with SimpleX is a viable tool to create ionization maps for Eta Car.

  18. The structure of the solar wind in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Lee, Christina On-Yee

    2010-12-01

    This dissertation is devoted to expanding our understanding of the solar wind structure in the inner heliosphere and variations therein with solar activity. Using spacecraft observations and numerical models, the origins of the large-scale structures and long-term trends of the solar wind are explored in order to gain insights on how our Sun determines the space environments of the terrestrial planets. I use long term measurements of the solar wind density, velocity, interplanetary magnetic field, and particles, together with models based on solar magnetic field data, to generate time series of these properties that span one solar rotation (˜27 days). From these time series, I assemble and obtain the synoptic overviews of the solar wind properties. The resulting synoptic overviews show that the solar wind around Mercury, Venus, Earth, and Mars is a complex co-rotating structure with recurring features and occasional transients. During quiet solar conditions, the heliospheric current sheet, which separates the positive interplanetary magnetic field from the negative, usually has a remarkably steady two- or four-sector structure that persists for many solar rotations. Within the sector boundaries are the slow and fast speed solar wind streams that originate from the open coronal magnetic field sources that map to the ecliptic. At the sector boundaries, compressed high-density and the related high-dynamic pressure ridges form where streams from different coronal source regions interact. High fluxes of energetic particles also occur at the boundaries, and are seen most prominently during the quiet solar period. The existence of these recurring features depends on how long-lived are their source regions. In the last decade, 3D numerical solar wind models have become more widely available. They provide important scientific tools for obtaining a more global view of the inner heliosphere and of the relationships between conditions at Mercury, Venus, Earth, and Mars. When

  19. Predicting Inner Heliospheric Solar Wind Conditions in Advance of Solar Probe Plus

    NASA Astrophysics Data System (ADS)

    Case, A. W.; Kasper, J. C.; Korreck, K. E.; Stevens, M. L.; Cohen, O.; Salem, C. S.; Halekas, J. S.; Larson, D. E.; Maruca, B. A.

    2012-12-01

    In advance of the upcoming inner heliospheric missions (Solar Orbiter and Solar Probe Plus) it is vital to have an accurate prediction of the range of solar wind conditions that occur between 9.5Rs and 0.7AU. These conditions will place constraints on instrument design and the operational modes that are used. In this paper, we discuss and compare different methods of predicting the solar wind bulk plasma parameters. One method uses observed 1AU conditions observed with the Wind spacecraft combined with scaling laws derived from Helios observations. We extend this simple model by using a more realistic solar wind velocity profile in addition to the Wind and Helios observations. Another method uses 3D MHD simulations from which solar wind conditions along a spacecraft trajectory can be extracted. We discuss some implications of these models in the design of the Solar Wind Electrons Alphas and Protons investigation, a suite of solar wind instruments being designed to fly on Solar Probe Plus.

  20. Efficient light harvesting with micropatterned 3D pyramidal photoanodes in dye-sensitized solar cells.

    PubMed

    Wooh, Sanghyuk; Yoon, Hyunsik; Jung, Jae-Hyun; Lee, Yong-Gun; Koh, Jai Hyun; Lee, Byoungho; Kang, Yong Soo; Char, Kookheon

    2013-06-11

    3D TiO2 photoanodes in dye-sensitized solar cells (DSCs) are fabricated by the soft lithographic technique for efficient light trapping. An extended strategy to the construction of randomized pyramid structure is developed by the conventional wet-etching of a silicon wafer for low-cost fabrication. Moreover, the futher enhancement of light absorption resulting in photocurrent increase is achieved by combining the 3D photoanode with a conventional scattering layer.

  1. Examination of 1D Solar Cell Model Limitations Using 3D SPICE Modeling: Preprint

    SciTech Connect

    McMahon, W. E.; Olson, J. M.; Geisz, J. F.; Friedman, D. J.

    2012-06-01

    To examine the limitations of one-dimensional (1D) solar cell modeling, 3D SPICE-based modeling is used to examine in detail the validity of the 1D assumptions as a function of sheet resistance for a model cell. The internal voltages and current densities produced by this modeling give additional insight into the differences between the 1D and 3D models.

  2. Nanoscale Analysis of a Hierarchical Hybrid Solar Cell in 3D

    PubMed Central

    Divitini, Giorgio; Stenzel, Ole; Ghadirzadeh, Ali; Guarnera, Simone; Russo, Valeria; Casari, Carlo S; Bassi, Andrea Li; Petrozza, Annamaria; Di Fonzo, Fabio; Schmidt, Volker; Ducati, Caterina

    2014-01-01

    A quantitative method for the characterization of nanoscale 3D morphology is applied to the investigation of a hybrid solar cell based on a novel hierarchical nanostructured photoanode. A cross section of the solar cell device is prepared by focused ion beam milling in a micropillar geometry, which allows a detailed 3D reconstruction of the titania photoanode by electron tomography. It is found that the hierarchical titania nanostructure facilitates polymer infiltration, thus favoring intermixing of the two semiconducting phases, essential for charge separation. The 3D nanoparticle network is analyzed with tools from stochastic geometry to extract information related to the charge transport in the hierarchical solar cell. In particular, the experimental dataset allows direct visualization of the percolation pathways that contribute to the photocurrent. PMID:25834481

  3. Imaging the Variable Solar Wind

    NASA Astrophysics Data System (ADS)

    DeForest, C.; Howard, T. A.; Matthaeus, W. H.

    2013-05-01

    With the advent of wide-field Thomson scattering imagery from STEREO/SECCHI, it is possible to image the solar wind continuously from its origin in the low corona to large fractions of 1AU from the Sun. Although it is sensitive only to non-stationary density structures, Thomson imaging yields morphological insight and global perspective that are not directly available from in-situ data. I will review recent work on both large and small scale analysis. On large scales, it is now possible to track well-presented CMEs from the pre-eruptive structure to impact with in-situ probes, yielding positive identification of flux rope structure based on both positively tracked morphology and direct magnetic measurement. In some cases, plasma detected in-situ can be positively identified with particular pieces of pre-eruptive anatomy in the low corona. Some observed large-scale features are as-yet unexplained. In quiet solar wind, small ejecta and blobs are readily distinguished from disconnection events that may be identified by their morphology, and all can be tracked through the Alfvén surface boundary at 20-50 Rs into the solar wind proper. In the HI-1 field of view, the solar wind takes on a flocculated appearance, though most of the individual features lose image structure and cannot be tracked across the entire field of view. Analysis of individual ejecta and of the statistical properties of the flocculation pattern is yielding insights into the nature of fluctuations and origin of variability in the slow solar wind.

  4. The solar wind-magnetosphere-ionosphere system

    PubMed

    Lyon

    2000-06-16

    The solar wind, magnetosphere, and ionosphere form a single system driven by the transfer of energy and momentum from the solar wind to the magnetosphere and ionosphere. Variations in the solar wind can lead to disruptions of space- and ground-based systems caused by enhanced currents flowing into the ionosphere and increased radiation in the near-Earth environment. The coupling between the solar wind and the magnetosphere is mediated and controlled by the magnetic field in the solar wind through the process of magnetic reconnection. Understanding of the global behavior of this system has improved markedly in the recent past from coordinated observations with a constellation of satellite and ground instruments.

  5. A 3-D High Speed Photographic Survey For Bomb Dropping In The Wind Tunnel

    NASA Astrophysics Data System (ADS)

    Junren, Chen; Liangyi, Chen; Yuxian, Nie; Wenxing, Chen

    1989-06-01

    High speed Stereophotography may obtain 3-D information of the motion object. This paper deals with a high speed stereophotographic survey of dropping bomb in wind tunnel and measurement of its displacement, velocity, acceleration, angle of attack and yaw angle. Two high speed cinecameras are used, the two optical axes of the cameras are perpendicular to each other and in a plane being vertical to the plumb line. The optical axis of a camera (front camera) is parallel with the aircraft body, and the another (side camera) is perpendicular. Before taking the object and image distance of the two cameras must be measured by photographic method. The photographic rate is 304 fps.

  6. Constraints on Decreases in Eta Carinae's Mass-loss from 3D Hydrodynamic Simulations of Its Binary Colliding Winds

    NASA Technical Reports Server (NTRS)

    Madura, T. I.; Gull, T. R.; Okazaki, A. T.; Russell, C. M. P.; Owocki, S. P.; Groh, J. H.; Corcoran, M. F.; Hamaguchi, K.; Teodoro, M.

    2013-01-01

    Recent work suggests that the mass-loss rate of the primary star Eta-A in the massive colliding wind binary Eta Carinae dropped by a factor of 2-3 between 1999 and 2010. We present result from large- (+/- 1545 au) and small- (+/- 155 au) domain, 3D smoothed particle hydrodynamics (SPH) simulations of Eta Car's colliding winds for three Eta-A mass-loss rates ( (dot-M(sub Eta-A) = 2.4, 4.8 and 8.5 × 10(exp -4) M(solar)/ yr), investigating the effects on the dynamics of the binary wind-wind collision (WWC). These simulations include orbital motion, optically thin radiative cooling and radiative forces. We find that dot-M Eta-A greatly affects the time-dependent hydrodynamics at all spatial scales investigated. The simulations also show that the post-shock wind of the companion star Eta-B switches from the adiabatic to the radiative-cooling regime during periastron passage (Phi approx.= 0.985-1.02). This switchover starts later and ends earlier the lower the value of dot-M Eta-A and is caused by the encroachment of the wind of Eta-A into the acceleration zone of Eta-B's wind, plus radiative inhibition of Eta-B's wind by Eta-A. The SPH simulations together with 1D radiative transfer models of Eta-A's spectra reveal that a factor of 2 or more drop in dot-M EtaA should lead to substantial changes in numerous multiwavelength observables. Recent observations are not fully consistent with the model predictions, indicating that any drop in dot- M Eta-A was likely by a factor of approx. < 2 and occurred after 2004. We speculate that most of the recent observed changes in Eta Car are due to a small increase in the WWC opening angle that produces significant effects because our line of sight to the system lies close to the dense walls of the WWC zone. A modest decrease in dot-M Eta-A may be responsible, but changes in the wind/stellar parameter of Eta-B, while less likely, cannot yet be fully ruled out. We suggest observations during Eta-Car's next periastron in 2014 to further

  7. 3-D numerical simulations of eruption clouds: Effects of the environmental wind on the turbulent mixing

    NASA Astrophysics Data System (ADS)

    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

  8. Impact of the 3-D model strategy on science learning of the solar system

    NASA Astrophysics Data System (ADS)

    Alharbi, Mohammed

    The purpose of this mixed method study, quantitative and descriptive, was to determine whether the first-middle grade (seventh grade) students at Saudi schools are able to learn and use the Autodesk Maya software to interact and create their own 3-D models and animations and whether their use of the software influences their study habits and their understanding of the school subject matter. The study revealed that there is value to the science students regarding the use of 3-D software to create 3-D models to complete science assignments. Also, this study aimed to address the middle-school students' ability to learn 3-D software in art class, and then ultimately use it in their science class. The success of this study may open the way to consider the impact of 3-D modeling on other school subjects, such as mathematics, art, and geography. When the students start using graphic design, including 3-D software, at a young age, they tend to develop personal creativity and skills. The success of this study, if applied in schools, will provide the community with skillful young designers and increase awareness of graphic design and the new 3-D technology. Experimental method was used to answer the quantitative research question, are there significant differences applying the learning method using 3-D models (no 3-D, premade 3-D, and create 3-D) in a science class being taught about the solar system and its impact on the students' science achievement scores? Descriptive method was used to answer the qualitative research questions that are about the difficulty of learning and using Autodesk Maya software, time that students take to use the basic levels of Polygon and Animation parts of the Autodesk Maya software, and level of students' work quality.

  9. A new 3D LDV system for the NASA Ames 6 x 6 ft. wind tunnel

    NASA Technical Reports Server (NTRS)

    Owen, F. K.; Orngard, G. M.; Mcdevitt, T. K.

    1985-01-01

    An obvious extension of wind tunnel laser Doppler velocimetry (LDV), which is currently mainly limited to two-component measurements, would involve the measurement of three simultaneous velocity components. The present paper is concerned with an approach to reduce the degree of optical complexity involved in the design of a three-dimensional (3D) LDV system, taking into account the use of polarization separation. Such a system, utilizing polarization as well as color separation, has been designed and tested in a 6 x 6 foot supersonic wind tunnel. The considered instrument was designed for the on line measurement of three mean velocity components, turbulence levels, and shear stresses on a number of models under a wide variety of test conditions. Attention is given to optical details, data reduction, and sample application.

  10. Assessment of 3D aerodynamic effects on the behaviour of floating wind turbines

    NASA Astrophysics Data System (ADS)

    Manolas, D.; Riziotis, V.; Voutsinas, S.

    2014-12-01

    Current state-of-art models for floating wind turbines are built by merging separate modules addressing the four basic aspects leading to a compound hydro-servo-aero-elastic time domain solver. While current state-of-the-art models differ in many aspects, they all use the blade element momentum (BEM) aerodynamic modelling. Due to its low cost, BEM is the standard choice for design purposes. However the use of BEM entails several semi-empirical corrections and add-ons that need reconsideration and recalibration when new features appear. For floating wind turbines, the effect of the floater motions is such a new feature. In the present paper, this aspect is investigated by comparing BEM based results against 3D free-wake simulations. Deterministic as well as stochastic simulations are presented in pure aerodynamic and full aeroelastic context. It is confirmed that asymmetric inflow originating from yaw misalignment and shear give significant differences reflected on mean values and amplitudes.

  11. Methodology for the Assessment of 3D Conduction Effects in an Aerothermal Wind Tunnel Test

    NASA Technical Reports Server (NTRS)

    Oliver, Anthony Brandon

    2010-01-01

    This slide presentation reviews a method for the assessment of three-dimensional conduction effects during test in a Aerothermal Wind Tunnel. The test objectives were to duplicate and extend tests that were performed during the 1960's on thermal conduction on proturberance on a flat plate. Slides review the 1D versus 3D conduction data reduction error, the analysis process, CFD-based analysis, loose coupling method that simulates a wind tunnel test run, verification of the CFD solution, Grid convergence, Mach number trend, size trends, and a Sumary of the CFD conduction analysis. Other slides show comparisons to pretest CFD at Mach 1.5 and 2.16 and the geometries of the models and grids.

  12. Parameterization and Analysis of 3-D Solar Radiative Transfer in Clouds: Final Report

    SciTech Connect

    Jerry Y. Harrington

    2012-09-21

    This document reports on the research that we have done over the course of our two-year project. The report also covers the research done on this project during a 1 year no-cost extension of the grant. Our work has had two main, inter-related thrusts: The first thrust was to characterize the response of stratocumulus cloud structure and dynamics to systematic changes in cloud infrared radiative cooling and solar heating using one-dimensional radiative transfer models. The second was to couple a three-dimensional (3-D) solar radiative transfer model to the Large Eddy Simulation (LES) model that we use to simulate stratocumulus. The purpose of the studies with 3-D radiative transfer was to examine the possible influences of 3-D photon transport on the structure, evolution, and radiative properties of stratocumulus. While 3-D radiative transport has been examined in static cloud environments, few studies have attempted to examine whether the 3-D nature of radiative absorption and emission influence the structure and evolution of stratocumulus. We undertook this dual approach because only a small number of LES simulations with the 3-D radiative transfer model are possible due to the high computational costs. Consequently, LES simulations with a 1-D radiative transfer solver were used in order to examine the portions of stratocumulus parameter space that may be most sensitive to perturbations in the radiative fields. The goal was then to explore these sensitive regions with LES using full 3-D radiative transfer. Our overall goal was to discover whether 3-D radiative processes alter cloud structure and evolution, and whether this may have any indirect implications for cloud radiative properties. In addition, we collaborated with Dr. Tamas Varni, providing model output fields for his attempt at parameterizing 3-D radiative effects for cloud models.

  13. Solar Wind Speed Charged Dust

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Weimer, D.; Jian, L. K.; Luhmann, J. G.; Omidi, N.

    2009-04-01

    The correlation of the occurrence of magnetic disturbances, known as interplanetary field enhancements (IFEs), with the asteroid 2201 Oljato can only be explained as the interaction with charged dust in the asteroid's orbit, because the events occurred both before and after alignment with the asteroid. These single spacecraft observations did not determine how fast the dust was accelerated, or if they were affected at all by the solar wind. Shortly after STEREO A and B were launched, an IFE crossed the two spacecraft as well as ACE and Wind. This four-spacecraft configuration allowed us to determine that the disturbance was moving radially outward at 700 km/s, the solar wind speed. The conventional wisdom is that only the smallest dust particles can be affected by the solar wind, but examination of periods on STEREO when the spacecraft is being sprayed with multiple beta-meteoroid strikes shows no obvious correlation. Further, the IFEs are much less frequent than the "beta-meteoroid" impacts. Hence, it is possible that IFEs are associated with much larger dust particles, perhaps 1 micron-sized dust. If true, then those particles may be very dangerous albeit rare, possessing about 104 ergs.

  14. Wind forcing of upland lake hydrodynamics: implementation and validation of a 3D numerical model

    NASA Astrophysics Data System (ADS)

    Morales, L.; French, J.; Burningham, H.; Evans, C.; Battarbee, R.

    2010-12-01

    Upland lakes act as important archives of environmental change, yet inferences based on the analysis of sediment cores are frequently compromised by an incomplete understanding of the hydrodynamic processes controlling the distribution and completeness of lake sediment sequences and their linkages to wider environmental factors. Many upland lakes are characterized by complex vertical and horizontal circulation patterns induced by the action of wind on the water surface. Wind forcing is important not only for the resuspension of bottom sediments in shallow marginal areas, but may also control the broader distribution of sediment accumulation. The work presented here represents the first stage of a project aimed at elucidating the linkages between wind forcing and the distribution of bottom sediments in upland lakes and the extent to which simple 'sediment focusing' models provide an adequate basis for predicting optimal locations for the acquisition of core samples for palaeolimnological analysis. As a first step, a 3D numerical hydrodynamic model is implemented for Llyn Conwy, a small oligotrophic upland lake in North Wales, UK. This utilises the community ocean model, FVCOM, that solves the Navier-Stokes equations in 3D on an unstructured triangular mesh using the finite volume method. A new graphical user interface has been developed for FVCOM to facilitate pre- and post-processing of lake modelling problems. At Llyn Conwy, the model is forced using local meteorological data and validated against vertical temperature profiles recorded by a long-term buoy deployment and short-term observations of vertical current structure measured using an upward-looking acoustic doppler profiler and surface circulation obtained from GPS drifters. Challenges in the application of FVCOM to a small lake include the design of a mesh that ensures numerical stability whilst resolving a complex bathymetry, and the need for careful treatment of model 'spin-up'. Once calibrated, the

  15. Eight-moment approximation solar wind models

    NASA Technical Reports Server (NTRS)

    Olsen, Espen Lyngdal; Leer, Egil

    1995-01-01

    Heat conduction from the corona is important in the solar wind energy budget. Until now all hydrodynamic solar wind models have been using the collisionally dominated gas approximation for the heat conductive flux. Observations of the solar wind show particle distribution functions which deviate significantly from a Maxwellian, and it is clear that the solar wind plasma is far from collisionally dominated. We have developed a numerical model for the solar wind which solves the full equation for the heat conductive flux together with the conservation equations for mass, momentum, and energy. The equations are obtained by taking moments of the Boltzmann equation, using an 8-moment approximation for the distribution function. For low-density solar winds the 8-moment approximation models give results which differ significantly from the results obtained in models assuming the gas to be collisionally dominated. The two models give more or less the same results in high density solar winds.

  16. The Solar Photospheric Oxygen Abundance and the Role of 3D Model Atmospheres

    NASA Astrophysics Data System (ADS)

    Caffau, E.; Steffen, M.; Ludwig, H.-G.

    2008-09-01

    The solar oxygen abundance has undergone a major downward revision in the last decade, reputedly as a result of employing 3D hydrodynamical simulations to model the inhomogeneous structure of the solar photosphere. The very low oxygen abundance advocated by Asplund et al. 2004, A(O)=8.66, together with the downward revision of the abundances of other key elements, has created serious problems for solar models to explain the helioseismic measurements. In an effort to contribute to the dispute of whether the Sun has "solar" or "sub-solar" abundances, we have re-derived its photospheric abundance of oxygen, nitrogen, and other elements, independently of previous analyses. We applied a state-of-the art 3D (CO5BOLD) hydrodynamical simulation of the solar granulation as well as different 1D model atmospheres for the line by line spectroscopic abundance determinations. The analysis is based on both standard disk-center and full-disk spectral atlases; for oxygen we acquired in addition spectra at different heliocentric angles. The derived abundances are the result of equivalent width and/or line profile fitting of the available atomic lines. Our recommended oxygen abundance is A(O)=8.76+- 0.07, 0.1 dex higher than the value of Asplund et al. (2004). Our current estimate of the overall solar metallicity is 0.014< Z<0.016. Questions we discuss include: (i) Is the general downward revision of the solar abundances a 3D effect? (ii) How large are the abundance corrections due to horizontal inhomogeneities? (iii) What is the main reason for the differences between the abundances obtained in our study and those derived by Apslund and coworkers? (iv) How large are the uncertainties in the observed solar spectra? (v) What is the reason why the two forbidden oxygen lines, [OI] lambda 630 nm and [OI] lambda 636.3 nm, give significantly different answers for the solar oxygen abundance?

  17. Calibration of 3-D wind measurements on a single engine research aircraft

    NASA Astrophysics Data System (ADS)

    Mallaun, C.; Giez, A.; Baumann, R.

    2015-02-01

    An innovative calibration method for the wind speed measurement using a boom mounted Rosemount model 858 AJ air velocity probe is introduced. The method is demonstrated for a sensor system installed on a medium size research aircraft which is used for measurements in the atmospheric boundary layer. The method encounters a series of coordinated flight manoeuvres to directly estimate the aerodynamic influences on the probe and to calculate the measurement uncertainties. The introduction of a differential Global Positioning System (DGPS) combined with a high accuracy Inertial Reference System (IRS) has brought major advances to airborne measurement techniques. The exact determination of geometrical height allows the use of the pressure signal as an independent parameter. Furthermore, the exact height information and the stepwise calibration process lead to maximum accuracy. The results show a measurement uncertainty for the aerodynamic influence of the dynamic and static pressures of 0.1 hPa. The applied parametrisation does not require any height dependencies or time shifts. After extensive flight tests a correction for the flow angles (attack and sideslip angles) was found, which is necessary for a successful wind calculation. A new method is demonstrated to correct for the aerodynamic influence on the sideslip angle. For the 3-D wind vector (with 100 Hz resolution) a novel error propagation scheme is tested, which determines the measurement uncertainties to be 0.3 m s-1 for the horizontal and 0.2 m s-1 for the vertical wind components.

  18. Calibration of 3-D wind measurements on a single-engine research aircraft

    NASA Astrophysics Data System (ADS)

    Mallaun, C.; Giez, A.; Baumann, R.

    2015-08-01

    An innovative calibration method for the wind speed measurement using a boom-mounted Rosemount model 858 AJ air velocity probe is introduced. The method is demonstrated for a sensor system installed on a medium-size research aircraft which is used for measurements in the atmospheric boundary layer. The method encounters a series of coordinated flight manoeuvres to directly estimate the aerodynamic influences on the probe and to calculate the measurement uncertainties. The introduction of a differential Global Positioning System (DGPS) combined with a high-accuracy inertial reference system (IRS) has brought major advances to airborne measurement techniques. The exact determination of geometrical height allows the use of the pressure signal as an independent parameter. Furthermore, the exact height information and the stepwise calibration process lead to maximum accuracy. The results show a measurement uncertainty for the aerodynamic influence of the dynamic and static pressures of 0.1 hPa. The applied parametrisation does not require any height dependencies or time shifts. After extensive flight tests a correction for the flow angles (attack and sideslip angles) was found, which is necessary for a successful wind calculation. A new method is demonstrated to correct for the aerodynamic influence on the sideslip angle. For the three-dimensional (3-D) wind vector (with 100 Hz resolution) a novel error propagation scheme is tested, which determines the measurement uncertainties to be 0.3 m s-1 for the horizontal and 0.2 m s-1 for the vertical wind components.

  19. A 3-D Look at Wind-Sculpted Ridges in Aeolis

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Layers of bedrock etched by wind to form sharp, elongated ridges known to geomorphologists as yardangs are commonplace in the southern Elysium Planitia/southern Amazonis region of Mars. The ridges shown in this 3-D composite of two overlapping Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images occur in the eastern Aeolis region of southern Elysium Planitia near 2.3oS, 206.8oW. To view the picture in stereo, you need red-blue 3-D glasses (red filter over the left eye, blue over the right). For wind to erode bedrock into the patterns seen here, the rock usually must consist of something that is fine-grained and of nearly uniform grain size, such as sand. It must also be relatively easy to erode. For decades, most Mars researchers have interpreted these materials to be eroded deposits of volcanic ash. Nothing in the new picture shown here can support nor refute this earlier speculation. The entire area is mantled by light-toned dust. Small landslides within this thin dust layer form dark streaks on some of the steeper slopes in this picture (for more examples and explanations for these streaks, see previous web pages listed below).

    The stereo (3-D) picture was compiled using an off-nadir view taken by the MOC during the Aerobrake-1 subphase of the mission in January 1998 with a nadir (straight-down-looking) view acquired in October 2000. The total area shown is about 6.7 kilometers (4.2 miles) wide by 2.5 kilometers (1.5 miles) high and is illuminated by sunlight from the upper right. The relief in the stereo image is quite exaggerated: the ridges are between about 50 and 100 meters (about 165-330 feet) high. North is toward the lower right.

  20. 3D analysis of the performances degradation caused by series resistance in concentrator solar cells

    SciTech Connect

    Daliento, Santolo; Lancellotti, Laura

    2010-01-15

    This paper deals with the modeling of series resistance components in silicon concentrator solar cells. The main components of the macroscopic series resistance are analyzed by means of one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) numerical simulations. It is shown that the contribution of the lateral current flux, flowing along the emitter region, and of the transverse current flux, flowing along the metal grid, cannot be neglected and, hence, the operation of solar cells subjected to high current densities cannot be described by simple one-dimensional models. The percentage weight of 2D and 3D components on the total value of the series resistance is evaluated and rules for the proper design of the cell geometries are given. An analysis of the effectiveness of the most popular methods for the extraction of the series resistance from the I-V curves of solar cells is also proposed. (author)

  1. The Colorado Solar Wind Experiment

    NASA Astrophysics Data System (ADS)

    Munsat, Tobin; Han, Jia; Horanyi, Mihaly; Ulibarri, Zach; Wang, Xu; Yeo, Lihsia

    2016-10-01

    The Colorado Solar Wind Experiment (CSWE) is a new device developed at the Institute for Modeling Plasma, Atmospheres, and Cosmic Dust (IMPACT) at the University of Colorado. This large ion source is for studies of the interaction of solar wind plasma with planetary surfaces and cosmic dust, and for the investigation of plasma wake physics. With a plasma beam diameter of 12 cm at the source, ion energies of up to 1 keV, and ion flows of up to 1 mA/cm2, a large cross-section Kaufman Ion Source is used to create steady state plasma flow to model the solar wind in an experimental vacuum chamber. Chamber pressure can be reduced to 3e-5 Torr under operating conditions to suppress ion-neutral collisions and create a uniform ion velocity distribution. Diagnostic instruments such as a double Langmuir probe and an ion energy analyzer are mounted on a two-dimensional translation stage that allow the beam to be characterized throughout the chamber. Early experiments include the measurement of dust grain charging from the interaction with flowing plasma, and measurements of the plasma sheath created by the interaction of the flowing plasma impinging on a surface with a dipole magnetic field. This poster will describe the facility and the scientific results obtained to date.

  2. Characterizing the Solar Wind at L1

    NASA Astrophysics Data System (ADS)

    Jahn, J.; Elliott, H. A.

    2008-12-01

    The nature of solar wind-magnetosphere energy transfer plays a big role in understanding the time history and types of global-scale magnetospheric phenomena. However, systematic approaches to quantifying how the specific magnetospheric "modes" (if they can be called that) of substorms, SMCs, sawtooth events, and geomagnetic storms could be controlled by the solar wind are still difficult. We present a fresh approach to characterizing the solar wind and its time history using self-organizing maps. The thrust of this effort is geared towards detecting and classifying solar wind structure on time scales relevant for the magnetospheric responses of interest. Performing this characterization at the L1 point is ideal for uncovering solar wind- magnetosphere relationships. It also provides a very long, contiguous time series that helps us explore these relationships over a complete solar cycle. We present the technique and initial results of solar wind comparisons during and leading up to SMCs and sawtooth events.

  3. 77 FR 61597 - Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-10

    ... Energy Regulatory Commission Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind Lessee, LLC; Pacific Wind 2, LLC; Valentine Solar, LLC; EDF Renewable Development, Inc.; Notice of Petition for Declaratory Order Take notice that on September 27, 2012, Avalon...

  4. Powering an in-space 3D printer using solar light energy

    NASA Astrophysics Data System (ADS)

    Leake, Skye; McGuire, Thomas; Parsons, Michael; Hirsch, Michael P.; Straub, Jeremy

    2016-05-01

    This paper describes how a solar power source can enable in-space 3D printing without requiring conversion to electric power and back. A design for an in-space 3D printer is presented, with a particular focus on the power generation system. Then, key benefits are presented and evaluated. Specifically, the approach facilitates the design of a spacecraft that can be built, launched, and operated at very low cost levels. The proposed approach also facilitates easy configuration of the amount of energy that is supplied. Finally, it facilitates easier disposal by removing the heavy metals and radioactive materials required for a nuclear-power solution.

  5. A new 3D reconstruction method of small solar system bodies

    NASA Astrophysics Data System (ADS)

    Capanna, C.; Jorda, L.; Lamy, P.; Gesquiere, G.

    2011-10-01

    The 3D reconstruction of small solar system bodies consitutes an essential step toward understanding and interpreting their physical and geological properties. We propose a new reconstruction method by photoclinometry based on the minimization of the chisquare difference between observed and synthetic images by deformation of a 3D triangular mesh. This method has been tested on images of the two asteroids (2867) Steins and (21) Lutetia observed during ESA's ROSETTA mission, and it will be applied to elaborate digital terrain models from images of the asteroid (4) Vesta, the target of NASA's DAWN spacecraft.

  6. The Distribution of Solar Wind Speeds During Solar Minimum: Calibration for Numerical Solar Wind Modeling Constraints on the Source of the Slow Solar Wind (Postprint)

    DTIC Science & Technology

    2012-03-05

    2003], and that the solar wind speed/ magnetic field expansion relationship is coinci- dental and is merely a result of the coronal geometry. [ 3 ] Wang... field component is 300 nT. The azimuthal magnetic field com- MCGREGOR ET AL.: MODELING SOLAR MINIMUM SOLAR WIND SPEEDS A03101A03101 3 of 11 Approved for...superradial expansion of the magnetic field to account for the observed solar wind speed variation. We investigate the solar wind in the inner corona using

  7. Distributed Wind Cost Reduction: Learning from Solar

    SciTech Connect

    Tegen, Suzanne

    2016-02-23

    The distributed wind energy industry can learn several lessons from the solar industry regarding reducing soft costs. Suzanne Tegen presented this overview at the 2016 Distributed Wind Energy Association Business Conference in Washington, D.C., on February 23, 2016.

  8. Astrospheres and Solar-like Stellar Winds.

    PubMed

    Wood, Brian E

    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 Lyα 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.

  9. Numerical modeling of the solar wind turbulence

    DOE PAGES

    Kryukov, I.A.; Pogorelov, N.V.; Zank, G.P.; ...

    2012-05-21

    Here we describe an extension of the Multi-Scale Fluid-Kinetic Simulation Suite (MSFLUKSS) by adding a solar wind turbulence model and a fluid treatment of pickup ions. Numerical results are presented of the time-dependent solar wind modeling with the boundary conditions provided by the OMNI data. The distributions of plasma properties and interplanetary magnetic field are compared with the Voyager 2 observations in the distant solar wind.

  10. Comet Borrelly Slows Solar Wind

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Over 1300 energy spectra taken on September 22, 2001 from the ion and electron instruments on NASA's Deep Space 1 span a region of 1,400,000 kilometers (870,000 miles) centered on the closest approach to the nucleus of comet Borrelly. A very strong interaction occurs between the solar wind (horizontal red bands to left and right in figure) and the comet's surrounding cloud of dust and gas, the coma. Near Deep Space 1's closest approach to the nucleus, the solar wind picked up charged water molecules from the coma (upper green band near the center), slowing the wind sharply and creating the V-shaped energy structure at the center.

    Deep Space 1 completed its primary mission testing ion propulsion and 11 other advanced, high-risk technologies in September 1999. NASA extended the mission, taking advantage of the ion propulsion and other systems to undertake this chancy but exciting, and ultimately successful, encounter with the comet. More information can be found on the Deep Space 1 home page at http://nmp.jpl.nasa.gov/ds1/ .

    Deep Space 1 was launched in October 1998 as part of NASA's New Millennium Program, which is managed by JPL for NASA's Office of Space Science, Washington, D.C. The California Institute of Technology manages JPL for NASA.

  11. Effects of 3D Virtual Simulators in the Introductory Wind Energy Course: A Tool for Teaching Engineering Concepts

    SciTech Connect

    Do, Phuong T.; Moreland, John R.; Delgado, Catherine; Wilson, Kristina; Wang, Xiuling; Zhou, Chenn; Ice, Phil

    2013-01-01

    Our research provides an innovative solution for optimizing learning effectiveness and improving postsecondary education through the development of virtual simulators that can be easily used and integrated into existing wind energy curriculum. Two 3D virtual simulators are developed in our laboratory for use in an immersive 3D virtual reality (VR) system or for 3D display on a 2D screen. Our goal is to apply these prototypical simulators to train postsecondary students and professionals in wind energy education; and to offer experiential learning opportunities in 3D modeling, simulation, and visualization. The issue of transferring learned concepts to practical applications is a widespread problem in postsecondary education. Related to this issue is a critical demand to educate and train a generation of professionals for the wind energy industry. With initiatives such as the U.S. Department of Energy's “20% Wind Energy by 2030” outlining an exponential increase of wind energy capacity over the coming years, revolutionary educational reform is needed to meet the demand for education in the field of wind energy. These developments and implementation of Virtual Simulators and accompanying curriculum will propel national reforms, meeting the needs of the wind energy industrial movement and addressing broader educational issues that affect a number of disciplines.

  12. Effects of 3D Virtual Simulators in the Introductory Wind Energy Course: A Tool for Teaching Engineering Concepts

    DOE PAGES

    Do, Phuong T.; Moreland, John R.; Delgado, Catherine; ...

    2013-01-01

    Our research provides an innovative solution for optimizing learning effectiveness and improving postsecondary education through the development of virtual simulators that can be easily used and integrated into existing wind energy curriculum. Two 3D virtual simulators are developed in our laboratory for use in an immersive 3D virtual reality (VR) system or for 3D display on a 2D screen. Our goal is to apply these prototypical simulators to train postsecondary students and professionals in wind energy education; and to offer experiential learning opportunities in 3D modeling, simulation, and visualization. The issue of transferring learned concepts to practical applications is amore » widespread problem in postsecondary education. Related to this issue is a critical demand to educate and train a generation of professionals for the wind energy industry. With initiatives such as the U.S. Department of Energy's “20% Wind Energy by 2030” outlining an exponential increase of wind energy capacity over the coming years, revolutionary educational reform is needed to meet the demand for education in the field of wind energy. These developments and implementation of Virtual Simulators and accompanying curriculum will propel national reforms, meeting the needs of the wind energy industrial movement and addressing broader educational issues that affect a number of disciplines.« less

  13. n-ZnO/p-Si 3D heterojunction solar cells in Si holey arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Mei; Golberg, Dmitri; Bando, Yoshio; Fukata, Naoki

    2012-01-01

    A wafer-scale, low-cost solar cell based on n-ZnO/p-Si 3D heterojunction arrays on holey Si substrates has been fabricated. This device shows a power-conversion efficiency of 1.2% and high photosensitivity. The present n-ZnO/p-Si heterojunction architectures are envisaged as potentially valuable candidates for next-generation photovoltaics.A wafer-scale, low-cost solar cell based on n-ZnO/p-Si 3D heterojunction arrays on holey Si substrates has been fabricated. This device shows a power-conversion efficiency of 1.2% and high photosensitivity. The present n-ZnO/p-Si heterojunction architectures are envisaged as potentially valuable candidates for next-generation photovoltaics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11752e

  14. Análisis DEM 3D de arcos en regiones activas solares

    NASA Astrophysics Data System (ADS)

    Nuevo, F. A.; Mandrini, C. H.; Vásquez, A. M.; López Fuentes, M.

    2016-08-01

    The solar corona is highly organized by the magnetic field. Because of their temperature and density, magnetic loops are directly observable in active regions (ARs) in the extreme ultraviolet (EUV) and soft X-ray images. The observational determination of the three-dimensional (3D) distribution of basic physical parameters (electronic density and temperature, and magnetic field) is a fundamental constraint of coronal heating models. In this work we develop a technique of differential emission measure (DEM) analysis and we apply it an EUV loop identified in the images of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). The DEM is determined after background subtraction and the electronic density and temperature in the loop are estimated from its moments. The 3D structure of the magnetic field in the loop and its intensity are modeled using linear force free field extrapolations based on AR magnetograms. In this work we show preliminary results of this technique.

  15. The solar silicon abundance based on 3D non-LTE calculations

    NASA Astrophysics Data System (ADS)

    Amarsi, A. M.; Asplund, M.

    2017-01-01

    We present 3D non-local thermodynamic equilibrium (non-LTE) radiative transfer calculations for silicon in the solar photosphere, using an extensive model atom that includes recent, realistic neutral hydrogen collisional cross-sections. We find that photon losses in the Si I lines give rise to slightly negative non-LTE abundance corrections of the order of -0.01 dex. We infer a 3D non-LTE-based solar silicon abundance of lg ɛ_{Si{⊙}}=7.51 dex. With silicon commonly chosen to be the anchor between the photospheric and meteoritic abundances, we find that the meteoritic abundance scale remains unchanged compared with the Asplund et al. and Lodders et al. results.

  16. Correlations Between Neutral and Ionized Solar Wind

    NASA Astrophysics Data System (ADS)

    Collier, M.; Pilkerton, B.; Moore, T.

    The Low Energy Neutral Atom (LENA) Imager on the IMAGE spacecraft has observed the neutral component of the solar wind (JGR, 106, 24,893, 2001) independently adumbrated by Akasofu and Dessler about forty years ago. Neutral solar wind is formed by solar wind charge exchange with interstellar neutrals, dust and the Earth's exosphere, in addition to any intrinsically neutral component. Here we report the results of a statistical study correlating the solar wind fluxes observed by ACE during late 2000 and throughout 2001 with neutral solar wind fluxes observed by LENA. The average correlation coefficient between the neutral and ionized solar wind is 0.66 with "good" correlations (peak correlation coefficient above 0.80) occurring about 28% of the time. The results are similar to those obtained by in-situ multi-spacecraft correlation studies. In this study, however, IMAGE is almost never in the solar wind or magnetosheath. The slope of the relationship between the neutral solar wind flux and the solar wind flux shows a peak in the upstream direction, but shifted toward higher ecliptic longitudes than the interstellar neutral (ISN) flow direction by about 20 degrees. The estimated peak interstellar neutral upstream density is about 10-2 cm-3.

  17. JP3D compression of solar data-cubes: Photospheric imaging and spectropolarimetry

    NASA Astrophysics Data System (ADS)

    Del Moro, Dario; Giovannelli, Luca; Pietropaolo, Ermanno; Berrilli, Francesco

    2017-02-01

    Hyperspectral imaging is an ubiquitous technique in solar physics observations and the recent advances in solar instrumentation enabled us to acquire and record data at an unprecedented rate. The huge amount of data which will be archived in the upcoming solar observatories press us to compress the data in order to reduce the storage space and transfer times. The correlation present over all dimensions, spatial, temporal and spectral, of solar data-sets suggests the use of a 3D base wavelet decomposition, to achieve higher compression rates. In this work, we evaluate the performance of the recent JPEG2000 Part 10 standard, known as JP3D, for the lossless compression of several types of solar data-cubes. We explore the differences in: a) The compressibility of broad-band or narrow-band time-sequence; I or V Stokes profiles in spectropolarimetric data-sets; b) Compressing data in [x,y, λ] packages at different times or data in [x,y,t] packages of different wavelength; c) Compressing a single large data-cube or several smaller data-cubes; d) Compressing data which is under-sampled or super-sampled with respect to the diffraction cut-off.

  18. The Solar Wind Ion Composition Spectrometer

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.; Geiss, J.; Balsiger, H.; Bedini, P.; Cain, J. C.; Fisher, J.; Fisk, L. A.; Galvin, A. B.; Gliem, F.; Hamilton, D. C.

    1992-01-01

    The Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses is designed to determine uniquely the elemental and ionic-charge composition, and the temperatures and mean speeds of all major solar-wind ions, from H through Fe, at solar wind speeds ranging from 175 km/s (protons) to 1280 km/s (Fe(8+)). The instrument, which covers an energy per charge range from 0.16 to 59.6 keV/e in about 13 min, combines an electrostatic analyzer with postacceleration, followed by a time-of-flight and energy measurement. The measurements made by SWICS will have an impact on many areas of solar and heliospheric physics, in particular providing essential and unique information on: (1) conditions and processes in the region of the corona where the solar wind is accelerated; (2) the location of the source regions of the solar wind in the corona; (3) coronal heating processes; (4) the extent and causes of variations in the composition of the solar atmosphere; (5) plasma processes in the solar wind; (6) the acceleration of energetic particles in the solar wind; (7) the thermalization and acceleration of interstellar ions in the solar wind, and their composition; and (8) the composition, charge states, and behavior of the plasma in various regions of the Jovian magnetosphere.

  19. Wind loading on solar collectors

    NASA Astrophysics Data System (ADS)

    Bhaduri, S.; Murphy, L. M.

    1985-06-01

    The present design methodology for the determination of wind loading on the various solar collectors were reviewed and assessed. The total force coefficients of flat plates of aspect ratios 1.0 and 3.0, respectively, at various angles of attack obtained by using the guidelines of the ANSI A58.1-1982, were compared with those obtained by using the methodology of the ASCE Task Committee, 1961, and the experimental results of the full-scale test of heliostats by Peglow. The turbulent energy spectra, currently employed in the building code, are compared with those of Kaimal et al., Lumley, and Ponofsky for wind velocities of 20.0 m/s and 40.24 m/s at an elevation of 9.15 m. The longitudinal spectra of the building code overestimates the Kaimal spectra in the frequency range of 0.007 Hz to 0.08 Hz and underestimates beyond the frequency of 0.08 Hz. The peak angles of attack, on the heliostat, stowed in horizontal position, due to turbulent vertical and lateral components of wind velocity, were estimated by using Daniel's methodology for three wind velocities and compared with the value suggested by the code. The experimental results of a simple test in the laboratory indicate the feasibility of decreasing the drag forces of the flat plate by reducing the solidity ratio.

  20. Solar wind thermal electron distributions

    SciTech Connect

    Phillips, J.L.; Gosling, J.T.

    1991-01-01

    Solar wind thermal electron distributions exhibit distinctive trends which suggest Coulomb collisions and geometric expansion in the interplanetary magnetic field play keys roles in electron transport. We introduce a simple numerical model incorporating these mechanisms, discuss the ramifications of model results, and assess the validity of the model in terms of ISEE-3 and Ulysses observations. Although the model duplicates the shape of the electron distributions, and explains certain other observational features, observed gradients in total electron temperature indicate the importance of additional heating mechanisms. 5 refs., 7 figs.

  1. Fabrication of solution processed 3D nanostructured CuInGaS₂ thin film solar cells.

    PubMed

    Chu, Van Ben; Cho, Jin Woo; Park, Se Jin; Hwang, Yun Jeong; Park, Hoo Keun; Do, Young Rag; Min, Byoung Koun

    2014-03-28

    In this study we demonstrate the fabrication of CuInGaS₂ (CIGS) thin film solar cells with a three-dimensional (3D) nanostructure based on indium tin oxide (ITO) nanorod films and precursor solutions (Cu, In and Ga nitrates in alcohol). To obtain solution processed 3D nanostructured CIGS thin film solar cells, two different precursor solutions were applied to complete gap filling in ITO nanorods and achieve the desirable absorber film thickness. Specifically, a coating of precursor solution without polymer binder material was first applied to fill the gap between ITO nanorods followed by deposition of the second precursor solution in the presence of a binder to generate an absorber film thickness of ∼1.3 μm. A solar cell device with a (Al, Ni)/AZO/i-ZnO/CdS/CIGS/ITO nanorod/glass structure was constructed using the CIGS film, and the highest power conversion efficiency was measured to be ∼6.3% at standard irradiation conditions, which was 22.5% higher than the planar type of CIGS solar cell on ITO substrate fabricated using the same precursor solutions.

  2. Simulations of Solar Wind Turbulence

    NASA Technical Reports Server (NTRS)

    Goldstein, Melvyn L.; Usmanov, A. V.; Roberts, D. A.

    2008-01-01

    Recently we have restructured our approach to simulating magnetohydrodynamic (MHD) turbulence in the solar wind. Previously, we had defined a 'virtual' heliosphere that contained, for example, a tilted rotating current sheet, microstreams, quasi-two-dimensional fluctuations as well as Alfven waves. In this new version of the code, we use the global, time-stationary, WKB Alfven wave-driven solar wind model developed by Usmanov and described in Usmanov and Goldstein [2003] to define the initial state of the system. Consequently, current sheets, and fast and slow streams are computed self-consistently from an inner, photospheric, boundary. To this steady-state configuration, we add fluctuations close to, but above, the surface where the flow become super-Alfvenic. The time-dependent MHD equations are then solved using a semi-discrete third-order Central Weighted Essentially Non-Oscillatory (CWENO) numerical scheme. The computational domain now includes the entire sphere; the geometrical singularity at the poles is removed using the multiple grid approach described in Usmanov [1996]. Wave packets are introduced at the inner boundary such as to satisfy Faraday's Law [Yeh and Dryer, 1985] and their nonlinear evolution are followed in time.

  3. Solar Wind Elemental Abundances from GENESIS Collectors

    NASA Astrophysics Data System (ADS)

    Burnett, D. S.; Woolum, D. S.; Jurewicz, A. J. G.; McKeegan, K. D.; Guan, Y.

    2007-03-01

    GENESIS bulk solar wind analyses were made by SIMS on Si, Sandia diamond-like-C, and epitaxial Si on sapphire (SoS). Preliminary Fe, Mg, Ca, Cr and Na fluences are calculated. The eventual goal is to test for fractionation (or lack thereof) of solar-wind

  4. Average thermal characteristics of solar wind electrons

    NASA Technical Reports Server (NTRS)

    Montgomery, M. D.

    1972-01-01

    Average solar wind electron properties based on a 1 year Vela 4 data sample-from May 1967 to May 1968 are presented. Frequency distributions of electron-to-ion temperature ratio, electron thermal anisotropy, and thermal energy flux are presented. The resulting evidence concerning heat transport in the solar wind is discussed.

  5. Solar wind influence on Jupiter's aurora

    NASA Astrophysics Data System (ADS)

    Gyalay, Szilard; Vogt, Marissa F.; Withers, Paul; Bunce, Emma J.

    2016-10-01

    Jupiter's main auroral emission is driven by a system of corotation enforcement currents that arises to speed up outflowing Iogenic plasma and is not due to the magnetosphere-solar wind interaction like at Earth. The solar wind is generally expected to have only a small influence on Jupiter's magnetosphere and aurora compared to the influence of rotational stresses due to the planet's rapid rotation. However, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the position and brightness of the UV auroral emissions. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter we have identified intervals of high and low solar wind dynamic pressure in the Galileo dataset, and use this information to quantify how a magnetospheric compression affects the magnetospheric field configuration. We have developed separate spatial fits to the compressed and nominal magnetic field data, accounting for variations with radial distance and local time. These two fits can be used to update the flux equivalence mapping model of Vogt et al. (2011), which links auroral features to source regions in the middle and outer magnetosphere. The updated version accounts for changing solar wind conditions and provides a way to quantify the expected solar wind-induced variability in the ionospheric mapping of the main auroral emission, satellite footprints, and other auroral features. Our results are highly relevant to interpretation of the new auroral observations from the Juno mission.

  6. The solar wind mass flux problem

    NASA Technical Reports Server (NTRS)

    Leer, E.; Holzer, T. E.

    1991-01-01

    The variation of the proton flux with coronal temperature and density in thermally driven solar wind models is discussed. It is shown that the rapid increase of the proton flux with increasing temperature can be reduced by adiabatic cooling of the expanding plasma. A significant coronal helium abundance can also act as a 'regulator' for the solar wind proton flux.

  7. Sources of solar wind over the solar activity cycle

    PubMed Central

    Poletto, Giannina

    2012-01-01

    Fast solar wind has been recognized, about 40 years ago, to originate in polar coronal holes (CHs), that, since then, have been identified with sources of recurrent high speed wind streams. As of today, however, there is no general consensus about whether there are, within CHs, preferential locations where the solar wind is accelerated. Knowledge of slow wind sources is far from complete as well. Slow wind observed in situ can be traced back to its solar source by backward extrapolation of magnetic fields whose field lines are streamlines of the outflowing plasma. However, this technique often has not the necessary precision for an indisputable identification of the region where wind originates. As the Sun progresses through its activity cycle, different wind sources prevail and contribute to filling the heliosphere. Our present knowledge of different wind sources is here summarized. Also, a Section addresses the problem of wind acceleration in the low corona, as inferred from an analysis of UV data, and illustrates changes between fast and slow wind profiles and possible signatures of changes along the solar cycle. A brief reference to recent work about the deep roots of solar wind and their changes over different solar cycles concludes the review. PMID:25685421

  8. Sources of solar wind over the solar activity cycle.

    PubMed

    Poletto, Giannina

    2013-05-01

    Fast solar wind has been recognized, about 40 years ago, to originate in polar coronal holes (CHs), that, since then, have been identified with sources of recurrent high speed wind streams. As of today, however, there is no general consensus about whether there are, within CHs, preferential locations where the solar wind is accelerated. Knowledge of slow wind sources is far from complete as well. Slow wind observed in situ can be traced back to its solar source by backward extrapolation of magnetic fields whose field lines are streamlines of the outflowing plasma. However, this technique often has not the necessary precision for an indisputable identification of the region where wind originates. As the Sun progresses through its activity cycle, different wind sources prevail and contribute to filling the heliosphere. Our present knowledge of different wind sources is here summarized. Also, a Section addresses the problem of wind acceleration in the low corona, as inferred from an analysis of UV data, and illustrates changes between fast and slow wind profiles and possible signatures of changes along the solar cycle. A brief reference to recent work about the deep roots of solar wind and their changes over different solar cycles concludes the review.

  9. Electric Current Filamentation Induced by 3D Plasma Flows in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Nickeler, Dieter H.; Wiegelmann, Thomas; Karlický, Marian; Kraus, Michaela

    2017-03-01

    Many magnetic structures in the solar atmosphere evolve rather slowly, so they can be assumed as (quasi-)static or (quasi-)stationary and represented via magnetohydrostatic (MHS) or stationary magnetohydrodynamic (MHD) equilibria, respectively. While exact 3D solutions would be desired, they are extremely difficult to find in stationary MHD. We construct solutions with magnetic and flow vector fields that have three components depending on all three coordinates. We show that the noncanonical transformation method produces quasi-3D solutions of stationary MHD by mapping 2D or 2.5D MHS equilibria to corresponding stationary MHD states, that is, states that display the same field-line structure as the original MHS equilibria. These stationary MHD states exist on magnetic flux surfaces of the original 2D MHS states. Although the flux surfaces and therefore also the equilibria have a 2D character, these stationary MHD states depend on all three coordinates and display highly complex currents. The existence of geometrically complex 3D currents within symmetric field-line structures provides the basis for efficient dissipation of the magnetic energy in the solar corona by ohmic heating. We also discuss the possibility of maintaining an important subset of nonlinear MHS states, namely force-free fields, by stationary flows. We find that force-free fields with nonlinear flows only arise under severe restrictions of the field-line geometry and of the magnetic flux density distribution.

  10. 2D Feature Recognition And 3d Reconstruction In Solar Euv Images

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.

    2005-05-01

    EUV images show the solar corona in a typical temperature range of T >rsim 1 MK, which encompasses the most common coronal structures: loops, filaments, and other magnetic structures in active regions, the quiet Sun, and coronal holes. Quantitative analysis increasingly demands automated 2D feature recognition and 3D reconstruction, in order to localize, track, and monitor the evolution of such coronal structures. We discuss numerical tools that “fingerprint” curvi-linear 1D features (e.g., loops and filaments). We discuss existing finger-printing algorithms, such as the brightness-gradient method, the oriented-connectivity method, stereoscopic methods, time-differencing, and space time feature recognition. We discuss improved 2D feature recognition and 3D reconstruction techniques that make use of additional a priori constraints, using guidance from magnetic field extrapolations, curvature radii constraints, and acceleration and velocity constraints in time-dependent image sequences. Applications of these algorithms aid the analysis of SOHO/EIT, TRACE, and STEREO/SECCHI data, such as disentangling, 3D reconstruction, and hydrodynamic modeling of coronal loops, postflare loops, filaments, prominences, and 3D reconstruction of the coronal magnetic field in general.

  11. Solar energy system with wind vane

    DOEpatents

    Grip, Robert E

    2015-11-03

    A solar energy system including a pedestal defining a longitudinal axis, a frame that is supported by the pedestal and that is rotateable relative to the pedestal about the longitudinal axis, the frame including at least one solar device, and a wind vane operatively connected to the frame to urge the frame relative to the pedestal about the longitudinal axis in response to wind acting on the wind vane.

  12. 3-D MHD disk wind simulations of jets and outflows from high-mass protostars

    NASA Astrophysics Data System (ADS)

    Staff, Jan E.; Tanaka, Kei; Tan, Jonathan C.; Zhang, Yichen; Liu, Mengyao

    2017-01-01

    We present the results of a series of nested, large scale, three-dimensional magnetohydrodynamics simulations of disk winds with a Blandford-Payne like magnetic field configuration, resolving scales from the stellar surface to beyond the core. The goal is to understand the structure of massive protostellar cores at various stages of their formation as the protostellar mass grows from a massive core. At each stage of a given protostellar mass, first, we study how jets and winds develop from the inner accretion disk to ~100 AU scales. We use the results from these simulations to dictate the inner boundary condition of a set of simulation extending to the core boundary at ~10,000 AU of an initially 60 solar mass core. We run separate simulations where the protostellar mass is 1, 2, 4, 8, 12, 16, and 24 Msun, and we are working on making a small grid of models in the context of the Turbulent Core Model with three different core masses and three different core surface densities. The wind is blown into the simulation box with properties derived from the previous jet simulations. We examine the opening angle of the outflow cavity and thus the star formation efficiency from the core due to outflow feedback. We find that the opening angle increases as the protostellar mass grows, but it is always less than 10 degrees, which is surprisingly small compared with previous analytic models. This is caused by the core which confines the outflow. Finally, we use our simulation results as input to a radiative transfer calculation, to compare with observations made by the SOMA survey.

  13. 3D radiative transfer simulations of Eta Carinae's inner colliding winds - II. Ionization structure of helium at periastron

    NASA Astrophysics Data System (ADS)

    Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Paardekooper, J.-P.

    2015-06-01

    Spectral observations of the massive colliding wind binary Eta Carinae show phase-dependent variations, in intensity and velocity, of numerous helium emission and absorption lines throughout the entire 5.54-yr orbit. Approaching periastron, the 3D structure of the wind-wind interaction region (WWIR) gets highly distorted due to the eccentric (e ˜ 0.9) binary orbit. The secondary star (ηB) at these phases is located deep within the primary's dense wind photosphere. The combination of these effects is thought to be the cause of the particularly interesting features observed in the helium lines at periastron. We perform 3D radiative transfer simulations of η Car's interacting winds at periastron. Using the SIMPLEX radiative transfer algorithm, we post-process output from 3D smoothed particle hydrodynamic simulations of the inner 150 au of the η Car system for two different primary star mass-loss rates (dot{M}_{η A}). Using previous results from simulations at apastron as a guide for the initial conditions, we compute 3D helium ionization maps. We find that, for higher dot{M}_{η A}, ηB He0+-ionizing photons are not able to penetrate into the pre-shock primary wind. He+ due to ηB is only present in a thin layer along the leading arm of the WWIR and in a small region close to the stars. Lowering dot{M}_{η A} allows ηB's ionizing photons to reach the expanding unshocked secondary wind on the apastron side of the system, and create a low fraction of He+ in the pre-shock primary wind. With apastron on our side of the system, our results are qualitatively consistent with the observed variations in strength and radial velocity of η Car's helium emission and absorption lines, which helps better constrain the regions where these lines arise.

  14. Capture of Solar Wind He++ by the Martian Exosphere

    NASA Astrophysics Data System (ADS)

    Chanteur, G. M.; Modolo, R.; Dubinin, E.

    The quantity of helium in the Martian atmosphere can be estimated from its emission line at 58 4nm Krasnopolsky and Gladstone Icarus vol 176 395-407 2005 and references therein Considering the necessary balance between losses through escape to the interplanetary medium and sources Krasnopolsky and coworkers have established that radioactive decay of uranium and thorium provides only one third of the lost helium They argue that the remaining two thirds should be captured from the solar wind This external source of Martian helium was also suggested by Barabash et al JGR 100 A11 21307 1995 Brecht JGR 102 A6 11287 1997 has estimated the deposition of protons into the Martian atmosphere from 3d hybrid simulation of the interaction of Mars with a solar wind made of protons and electrons only From these results Brecht gave an estimate of the deposition of solar helium ions into the Martian atmosphere based on scaling arguments In the recent past we have developed a consistent multi-species 3d hybrid model of the interaction of solar wind protons and alpha particles with the Martian plasma environment taking into account the ionisation of the oxygen and hydrogen neutral coronas of Mars Modolo et al Ann Geophys 23 433 2005 Neutral species are ionised by photons and by electron impacts the two processes are simulated consistently and independently through the specification of ionisation frequencies and cross sections Charge exchange reactions of protons and oxygen ions with hydrogen and oxygen atoms are taken into account

  15. New non-Doppler remote sensing technique for 3D wind field mapping

    NASA Astrophysics Data System (ADS)

    Belen'kii, Mikhail S.; Gimmestad, Gary G.; Gurvich, Alexander V.

    1994-06-01

    A new approach to the statistical analysis of fluctuating, photon-limited signals that permits us to accumulate and process the lidar returns without averaging of the reflected energy fluctuations is developed. This approach requires recording the photocounts for each pulse in a series of pulses and then determining photocount statistics. Based on the semiclassical theory of photodetection and Mandel's formula, a relationship has been obtained between the time-space cross correlation function and the cross spectrum of the lidar returns and corresponding photocount statistics. It is shown that the relative uncertainties of measuring the cross correlation or the cross spectrum of the lidar returns is determined by the general number of photocounts, but not by their mean value. A fast-scanning lidar system, which is based on a new photocounting analysis approach, is described for 3D wind field mapping in the atmosphere at altitudes up to 5 km. A program for the experimental verification of the new approach is presented.

  16. The quiescent corona and slow solar wind

    NASA Technical Reports Server (NTRS)

    Noci, G.; Kohl, J. L.; Antonucci, E.; Tondello, G.; Huber, M. C. E.; Fineschi, S.; Gardner, L. D.; Korendyke, C. M.; Nicolosi, P.; Romoli, M.; Spadaro, D.; Maccari, L.; Raymond, J. C.; Siegmund, O. H. W.; Benna, C.; Ciaravella, A.; Giordano, S.; Michels, J.; Modigliani, A.; Naletto, G.

    1997-01-01

    The observations of the ultraviolet coronagraph spectrometer (UVCS), operating onboard the Solar and Heliospheric Observatory (SOHO) spacecraft, are discussed. The purpose of the UVCS is the study of the quiescent coronal streamer and the slow solar wind. The observations started in January 1996. Polarized radiance data in the visible continuum were obtained. Some characteristics of the coronal streamer from the UVCS recorded data are discussed. A model for the source of the slow solar wind in the inner corona is proposed.

  17. Solar wind compressible structures at ion scales

    NASA Astrophysics Data System (ADS)

    Perrone, D.; Alexandrova, O.; Rocoto, V.; Pantellini, F. G. E.; Zaslavsky, A.; Maksimovic, M.; Issautier, K.; Mangeney, A.

    2014-12-01

    In the solar wind turbulent cascade, the energy partition between fluid and kinetic degrees of freedom, in the vicinity of plasma characteristic scales, i.e. ion and electron Larmor radius and inertial lengths, is still under debate. In a neighborhood of the ion scales, it has been observed that the spectral shape changes and fluctuations become more compressible. Nowadays, a huge scientific effort is directed to the comprehension of the link between macroscopic and microscopic scales and to disclose the nature of compressive fluctuations, meaning that if space plasma turbulence is a mixture of quasi-linear waves (as whistler or kinetic Alfvèn waves) or if turbulence is strong with formation of coherent structures responsible for dissipation. Here we present an automatic method to identify compressible coherent structures around the ion spectral break, using Morlet wavelet decomposition of magnetic signal from Cluster spacecraft and reconstruction of magnetic fluctuations in a selected scale range. Different kind of coherent structures have been detected: from soliton-like one-dimensional structures to current sheet- or wave-like two-dimensional structures. Using a multi-satellite analysis, in order to characterize 3D geometry and propagation in plasma rest frame, we recover that these structures propagate quasi-perpendicular to the mean magnetic field, with finite velocity. Moreover, without using the Taylor hypothesis, the spatial scales of coherent structures have been estimated. Our observations in the solar wind can provide constraints on theoretical modeling of small scale turbulence and dissipation in collisionless magnetized plasmas.

  18. Partial redistribution in 3D non-LTE radiative transfer in solar-atmosphere models

    NASA Astrophysics Data System (ADS)

    Sukhorukov, Andrii V.; Leenaarts, Jorrit

    2017-01-01

    Context. Resonance spectral lines such as H I Ly α, Mg II H&K, and Ca II H&K that form in the solar chromosphere, are influenced by the effects of 3D radiative transfer as well as partial redistribution (PRD). So far no one has modeled these lines including both effects simultaneously owing to the high computing demands of existing algorithms. Such modeling is, however, indispensable for accurate diagnostics of the chromosphere. Aims: We present a computationally tractable method to treat PRD scattering in 3D model atmospheres using a 3D non-local thermodynamic equilibrium (non-LTE) radiative transfer code. Methods: To make the method memory-friendly, we use the hybrid approximation for the redistribution integral. To make the method fast, we use linear interpolation on equidistant frequency grids. We verify our algorithm against computations with the RH code and analyze it for stability, convergence, and usefulness of acceleration using model atoms of Mg II with the H&K lines and H I with the Ly α line treated in PRD. Results: A typical 3D PRD solution can be obtained in a model atmosphere with 252 × 252 × 496 coordinate points in 50 000-200 000 CPU hours, which is a factor ten slower than computations assuming complete redistribution. We illustrate the importance of the joint action of PRD and 3D effects for the Mg II H&K lines for disk-center intensities, as well as the center-to-limb variation. Conclusions: The proposed method allows for the simulation of PRD lines in a time series of radiation-magnetohydrodynamic models, in order to interpret observations of chromospheric lines at high spatial resolution.

  19. The Contribution of Coronal Jets to the Solar Wind

    NASA Astrophysics Data System (ADS)

    Lionello, R.; Török, T.; Titov, V. S.; Leake, J. E.; Mikić, Z.; Linker, J. A.; Linton, M. G.

    2016-11-01

    Transient collimated plasma eruptions in the solar corona, commonly known as coronal (or X-ray) jets, are among the most interesting manifestations of solar activity. It has been suggested that these events contribute to the mass and energy content of the corona and solar wind, but the extent of these contributions remains uncertain. We have recently modeled the formation and evolution of coronal jets using a three-dimensional (3D) magnetohydrodynamic (MHD) code with thermodynamics in a large spherical domain that includes the solar wind. Our model is coupled to 3D MHD flux-emergence simulations, i.e., we use boundary conditions provided by such simulations to drive a time-dependent coronal evolution. The model includes parametric coronal heating, radiative losses, and thermal conduction, which enables us to simulate the dynamics and plasma properties of coronal jets in a more realistic manner than done so far. Here, we employ these simulations to calculate the amount of mass and energy transported by coronal jets into the outer corona and inner heliosphere. Based on observed jet-occurrence rates, we then estimate the total contribution of coronal jets to the mass and energy content of the solar wind to (0.4-3.0)% and (0.3-1.0)%, respectively. Our results are largely consistent with the few previous rough estimates obtained from observations, supporting the conjecture that coronal jets provide only a small amount of mass and energy to the solar wind. We emphasize, however, that more advanced observations and simulations (including parametric studies) are needed to substantiate this conjecture.

  20. 3D-Mössbauer spectroscopic microscope for mc-Si solar cell evaluation

    NASA Astrophysics Data System (ADS)

    Ino, Y.; Soejima, H.; Hayakawa, K.; Yukihira, K.; Tanaka, K.; Fujita, H.; Watanabe, T.; Ogai, K.; Moriguchi, K.; Harada, Y.; Yoshida, Y.

    2016-12-01

    A 3D-Mössbauer Spectroscopic Microscope is developed to evaluate Fe impurities in multi-crystalline Si solar cells, which combines the Mössbauer spectroscopic microscope with a scanning electron microscope (SEM), an electron beam induced current (EBIC), an electron backscatter diffraction (EBSD), and an electron energy analyzer (HV-CSA). In addition, a new moving-coil-actuator with a liner encoder of 100 nm-resolution is incorporated for the operations with both a constant velocity and a constant acceleration mode successfully with the same precision as that obtained by the conventional transducers. Furthermore, a new multi-capillary X-ray lens is designed to achieve a γ-ray spot size less than 100 μm in diameter. The new microscope provides us to investigate the space correlation between Fe impurities and the lattice defects such as grain boundaries in multi-crystalline Si solar cells.

  1. Global Network of Slow Solar Wind

    NASA Technical Reports Server (NTRS)

    Crooker, N. U.; Antiochos, S. K.; Zhao, X.; Neugebauer, M.

    2012-01-01

    The streamer belt region surrounding the heliospheric current sheet (HCS) is generally treated as the primary or sole source of the slow solar wind. Synoptic maps of solar wind speed predicted by the Wang-Sheeley-Arge model during selected periods of solar cycle 23, however, show many areas of slow wind displaced from the streamer belt. These areas commonly have the form of an arc that is connected to the streamer belt at both ends. The arcs mark the boundaries between fields emanating from different coronal holes of the same polarity and thus trace the paths of belts of pseudostreamers, i.e., unipolar streamers that form over double arcades and lack current sheets. The arc pattern is consistent with the predicted topological mapping of the narrow open corridor or singular separator line that must connect the holes and, thus, consistent with the separatrix-web model of the slow solar wind. Near solar maximum, pseudostreamer belts stray far from the HCS-associated streamer belt and, together with it, form a global-wide web of slow wind. Recognition of pseudostreamer belts as prominent sources of slow wind provides a new template for understanding solar wind stream structure, especially near solar maximum.

  2. Bimodal Solar Wind-Magnetosphere-Ionosphere Coupling

    NASA Astrophysics Data System (ADS)

    Siscoe, G.

    2005-05-01

    Regarding its coupling to the solar wind, the magnetosphere-ionosphere system appears to be schizophrenic. That is, it seems to manifest two modes with contradictory qualities, modes that alternate depending on solar wind conditions. Normal conditions elicit the normal mode (aka the solar wind-dominated mode). But extreme conditions bring out the un-normal mode (aka the ionosphere-dominated mode). This talk emphasizes the un-normal, ionosphere-dominated mode, which makes its presence during great magnetic storms. Then the magnetosphere-confining Chapman-Ferraro current system fades away to be replaced by the region 1 currents system which links the now dominant ionosphere to the whole of geospace out to and including the bow shock. Dst no longer responds to the ram pressure of the solar wind. The electrical potential across the polar cap stops growing as solar wind driving strengthens. Instead, it becomes bound to ionospheric conductance, which as the storm intensifies transforms under local instability. The ionosphere appears to lose its grip on magnetospheric convection, although this is not certain. The plasmasphere is stripped away, most likely to feed (by global circulation) an intensifying ring current. The outer magnetosphere begins a series of slow, macroscale convulsions. Huge parallel potentials possibly develop in the magnetosphere's outer regions, reacting against the ionosphere's domination. Compared to the solar wind-dominated magnetosphere, the ionosphere-dominated magnetosphere is comparatively unknown and, so, provides opportunities for significantly advancing our understanding of the coupled solar wind-magnetosphere-ionosphere system.

  3. Wave Modeling of the Solar Wind.

    PubMed

    Ofman, Leon

    The acceleration and heating of the solar wind have been studied for decades using satellite observations and models. However, the exact mechanism that leads to solar wind heating and acceleration is poorly understood. In order to improve the understanding of the physical mechanisms that are involved in these processes a combination of modeling and observational analysis is required. Recent models constrained by satellite observations show that wave heating in the low-frequency (MHD), and high-frequency (ion-cyclotron) range may provide the necessary momentum and heat input to coronal plasma and produce the solar wind. This review is focused on the results of several recent solar modeling studies that include waves explicitly in the MHD and the kinetic regime. The current status of the understanding of the solar wind acceleration and heating by waves is reviewed.

  4. Volumetric LiDAR scanning of a wind turbine wake and comparison with a 3D analytical wake model

    NASA Astrophysics Data System (ADS)

    Carbajo Fuertes, Fernando; Porté-Agel, Fernando

    2016-04-01

    A correct estimation of the future power production is of capital importance whenever the feasibility of a future wind farm is being studied. This power estimation relies mostly on three aspects: (1) a reliable measurement of the wind resource in the area, (2) a well-established power curve of the future wind turbines and, (3) an accurate characterization of the wake effects; the latter being arguably the most challenging one due to the complexity of the phenomenon and the lack of extensive full-scale data sets that could be used to validate analytical or numerical models. The current project addresses the problem of obtaining a volumetric description of a full-scale wake of a 2MW wind turbine in terms of velocity deficit and turbulence intensity using three scanning wind LiDARs and two sonic anemometers. The characterization of the upstream flow conditions is done by one scanning LiDAR and two sonic anemometers, which have been used to calculate incoming vertical profiles of horizontal wind speed, wind direction and an approximation to turbulence intensity, as well as the thermal stability of the atmospheric boundary layer. The characterization of the wake is done by two scanning LiDARs working simultaneously and pointing downstream from the base of the wind turbine. The direct LiDAR measurements in terms of radial wind speed can be corrected using the upstream conditions in order to provide good estimations of the horizontal wind speed at any point downstream of the wind turbine. All this data combined allow for the volumetric reconstruction of the wake in terms of velocity deficit as well as turbulence intensity. Finally, the predictions of a 3D analytical model [1] are compared to the 3D LiDAR measurements of the wind turbine. The model is derived by applying the laws of conservation of mass and momentum and assuming a Gaussian distribution for the velocity deficit in the wake. This model has already been validated using high resolution wind-tunnel measurements

  5. Solar Wind Earth Exchange Project (SWEEP)

    DTIC Science & Technology

    2016-10-28

    and highly charged ions of the solar wind. The main challenge in predicting the resultant photon flux in the X-ray energy bands is due to the...AFRL-AFOSR-UK-TR-2016-0035 Solar Wind Earth Exchange Project 140200 Steven Sembay UNIVERSITY OF LEICESTER Final Report 10/28/2016 DISTRIBUTION A...To) 01 Sep 2014 to 31 Aug 2016 4. TITLE AND SUBTITLE Solar Wind Earth Exchange Project (SWEEP) 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1

  6. DSCOVR High Time Resolution Solar Wind Measurements

    NASA Technical Reports Server (NTRS)

    Szabo, Adam

    2012-01-01

    The Deep Space Climate Observatory (DSCOVR), previously known as Triana, spacecraft is expected to be launched in late 2014. It will carry a fluxgate magnetometer, Faraday Cup solar wind detector and a top-hat electron electrostatic analyzer. The Faraday Cup will provide an unprecedented 10 vectors/sec time resolution measurement of the solar wind proton and alpha reduced distribution functions. Coupled with the 40 vector/sec vector magnetometer measurements, the identification of specific wave modes in the solar wind will be possible for the first time. The science objectives and data products of the mission will be discussed.

  7. On periodicity of solar wind phenomena

    NASA Technical Reports Server (NTRS)

    Verma, V. K.; Joshi, G. C.

    1995-01-01

    We have investigated the rate of occurrence of solar wind phenomena observed between 1972-1984 using power spectrum analysis. The data have been taken from the high speed solar wind (HSSW) streams catalogue published by Mavromichalaki et al. (1988). The power spectrum analysis of HSSW events indicate that HSSW stream events have a periodicity of 9 days. This periodicity of HSSW events is 1/3 of the 27 days period of coronal holes which are the major source of solar wind events. In our opinion the 9 days period may be the energy build up time to produce the HSSW stream events.

  8. Verification of high-speed solar wind stream forecasts using operational solar wind models

    NASA Astrophysics Data System (ADS)

    Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.; Nikolic, Ljubomir; Vennerstrom, Susanne; Schöngassner, Florian; Hofmeister, Stefan J.

    2016-07-01

    High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the Advanced Composition Explorer (ACE) spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation between the coronal hole area observed in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images and solar wind properties at the near-Earth environment, the WSA model establishes a link between properties of the open magnetic field lines extending from the photosphere to the corona and the background solar wind conditions. We found that both solar wind models are capable of predicting the large-scale features of the observed solar wind speed (root-mean-square error, RMSE ≈100 km/s) but tend to either overestimate (ESWF) or underestimate (WSA) the number of high-speed solar wind streams (threat score, TS ≈ 0.37). The predicted high-speed streams show typical uncertainties in the arrival time of about 1 day and uncertainties in the speed of about 100 km/s. General advantages and disadvantages of the investigated solar wind models are diagnosed and outlined.

  9. Solar wind tans young asteroids

    NASA Astrophysics Data System (ADS)

    2009-04-01

    A new study published in Nature this week reveals that asteroid surfaces age and redden much faster than previously thought -- in less than a million years, the blink of an eye for an asteroid. This study has finally confirmed that the solar wind is the most likely cause of very rapid space weathering in asteroids. This fundamental result will help astronomers relate the appearance of an asteroid to its actual history and identify any after effects of a catastrophic impact with another asteroid. ESO PR Photo 16a/09 Young Asteroids Look Old "Asteroids seem to get a ‘sun tan' very quickly," says lead author Pierre Vernazza. "But not, as for people, from an overdose of the Sun's ultraviolet radiation, but from the effects of its powerful wind." It has long been known that asteroid surfaces alter in appearance with time -- the observed asteroids are much redder than the interior of meteorites found on Earth [1] -- but the actual processes of this "space weathering" and the timescales involved were controversial. Thanks to observations of different families of asteroids [2] using ESO's New Technology Telescope at La Silla and the Very Large Telescope at Paranal, as well as telescopes in Spain and Hawaii, Vernazza's team have now solved the puzzle. When two asteroids collide, they create a family of fragments with "fresh" surfaces. The astronomers found that these newly exposed surfaces are quickly altered and change colour in less than a million years -- a very short time compared to the age of the Solar System. "The charged, fast moving particles in the solar wind damage the asteroid's surface at an amazing rate [3]", says Vernazza. Unlike human skin, which is damaged and aged by repeated overexposure to sunlight, it is, perhaps rather surprisingly, the first moments of exposure (on the timescale considered) -- the first million years -- that causes most of the aging in asteroids. By studying different families of asteroids, the team has also shown that an asteroid

  10. Interplanetary shocks and solar wind extremes

    NASA Astrophysics Data System (ADS)

    Vats, Hari

    The interplanetary shocks have a very high correlation with the annual sunspot numbers during the solar cycle; however the correlation falls very low on shorter time scale. Thus poses questions and difficulty in the predictability. Space weather is largely controlled by these interplanetary shocks, solar energetic events and the extremes of solar wind. In fact most of the solar wind extremes are related to the solar energetic phenomena. It is quite well understood that the energetic events like flares, filament eruptions etc. occurring on the Sun produce high speed extremes both in terms of density and speed. There is also high speed solar wind steams associated with the coronal holes mainly because the magnetic field lines are open there and the solar plasma finds it easy to escape from there. These are relatively tenuous high speed streams and hence create low intensity geomagnetic storms of higher duration. The solar flares and/or filament eruptions usually release excess coronal mass into the interplanetary medium and thus these energetic events send out high density and high speed solar wind which statistically found to produce more intense storms. The other extremes of solar wind are those in which density and speed are much lower than the normal values. Several such events have been observed and are found to produce space weather consequences of different kind. It is found that such extremes are more common around the maximum of solar cycle 20 and 23. Most of these have significantly low Alfven Mach number. This article is intended to outline the interplanetary and geomagnetic consequences of observed by ground based and satellite systems for the solar wind extremes.

  11. Properties of the very slow solar wind

    NASA Astrophysics Data System (ADS)

    Sanchez-Diaz, Eduardo; Segura, Kevin; Rouillard, Alexis P.; Lavraud, Benoit

    2015-04-01

    Solar wind plasma data taken between 0.29-0.9 AU by the twin HELIOS spacecraft reveals the frequent occurrence of very low radial wind speeds (200 < V < 300 km/s), very rarely measured near 1 AU. By analysing the occurrence as a function of heliocentric distance and time, we show that it is primarly measured inside 0.5 AU and mostly during solar maximum, although some very slow wind events were also measured during short periods at solar minimum. We show that the very slow wind is frequently measured during the passage of the solar wind plasma sheet usually detected in the vicinity of the heliospheric current sheet. By tracing these slow events back to the Sun and using a potential field reconstruction of the coronal magnetic field based on magnetograms taken by Mount Wilson Observatory, we compare the speed of the very slow wind with the geometry of the magnetic flux tube at its source. We discuss theoretical mechanisms that could explain the abundance and origin of this very slow wind, we also stress the importance of these findings for our understanding of solar wind structure. This study was carried out as part of the HELCATS FP7 project.

  12. Prospects for future solar-wind missions

    NASA Technical Reports Server (NTRS)

    Bochsler, P.; Moebius, E.

    1993-01-01

    Possible activities and future goals for solar wind research in the post Soho era are discussed. Two major enterprises which will open up important fields in the future study of the Sun are addressed. The first deals with in situ study of the solar corona, a region that has not been accessible for direct study in the past. This exploratory work will include the coronal heating and the acceleration of the solar wind much closer to its origin and the determination of the charge states of a large number of ions as a diagnostic tool for fractionation processes in these regions. The second major goal will be the setting up of a baseline for the isotopic composition in the solar system by studying a sample from the Sun in detail. These studies will be complemented by a direct comparison with extra solar samples of interstellar pick up ions, which become accessible with the same instrumentation as is necessary for the detailed investigation of the solar wind's isotopic composition. In order to achieve these goals, advanced composition experiments are developed to investigate the solar wind with enhanced mass resolution, considerably increased geometrical factor, and improved time resolution. The placing of sophisticated mass/charge spectrometers, with the ability to investigate both charge and velocity distributions with enhanced time resolution, in the solar wind acceleration region, is also proposed.

  13. The solar wind interaction with Venus

    NASA Technical Reports Server (NTRS)

    Luthmann, J. G.

    1992-01-01

    The Pioneer Venus Orbiter (PVO) mission has played a key role in establishing the nature of the solar wind interaction with Venus. Although earlier probes had determined that Venus presented an obstacle much smaller than the size of earth's magnetosphere to the solar wind, they did not carry out in situ measurements pertaining to solar wind interaction studies at low enough altitudes to determine why. They also did not provide datasets of sufficient duration to study the variability of the interaction of both short (one day) and long (solar cycle) timescales. The first 600 of the nearly 5000 orbits of PVO magnetometer data have been used to determine a very low upper limit on the intrinsic dipolar magnetic moment of Venus. The consequence of that low magnetic moment is that the solar wind interacts directly with the upper atmosphere and ionosphere. Relative to a dipolar field obstacle, the ionospheric obstacle is rather incompressible. A bow shock is observed to stand in front of the nearly Venus-sized ionospheric obstacle at a comparatively steady subsolar altitude of approximately 1.5 R(v) (Venus radii). This shock decelerates the supersonic solar wind plasma so that it can flow around the obstacle. It was found to change its average position in the terminator plane from about 2.4 R(v) to 2.1 R(v) as the solar cycle progressed from the 1978 orbit insertion near solar maximum through the 1986-87 solar minimum, and back again during the latest solar activity increase. Between the bow shock and the ionosphere proper, the slowed solar wind plasma flow diverges near the subsolar point and makes its way across the terminator where it reaccelerates and continues anti-Sunward. The solar wind magnetic field, which is in effect frozen into the flowing plasma, is distorted in this 'magnetosheath' region so that it appears to hang up or drape over the dayside ionosphere before it slips around with the flow. These features of the solar wind interaction are also seen when the

  14. Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets

    NASA Technical Reports Server (NTRS)

    Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris

    2013-01-01

    A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

  15. Solar and Wind Site Screening Decision Trees

    EPA Pesticide Factsheets

    EPA and NREL created a decision tree to guide state and local governments and other stakeholders through a process for screening sites for their suitability for future redevelopment with solar photovoltaic (PV) energy and wind energy.

  16. Dissipation of Turbulence in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Goldstein, Melvyn L.

    2010-01-01

    I will describe the first three-dimensional (3-D) dispersion relations and wavenumber spectra of magnetic turbulence in the solar wind at sub-proton scales. The analysis takes advantage of the short separations of the Cluster spacecraft (d/sim approx.200 km) to apply the {it k}-filtering technique to the frequency range where the transition to sub-proton scales occurs. The dispersion diagrams show unambiguously that the cascade is carried by highly oblique Kinetic Alfven Wave with \\omega\\leq 0.1\\omega_{ci} in the plasma rest frame down to k_\\perp\\rho_i \\sim 2. The wavenumber spectra in the direction perpendicular to the mean magnetic field consists of two ranges of scales separated by a breakpoint in the interval [0.4,1] k_\\perp \\rho_i. Above the breakpoint, the spectra follow the Kolmogorov scaling k_\\perp^{-1.7}, consistent with existing theoretical predictions. Below the breakpoint, the spectra steepen to \\sim k_\\perp^{-4.5}. We conjecture that the turbulence undergoes a {\\it transition-range}, where part of energy is dissipated into proton heating via Landau damping, and the remaining energy cascades down to electron scales where electron Landau damping may predominate.

  17. Parameterization of Solar Radiative Fluxes For 3d-inhomogeneous Clouds

    NASA Astrophysics Data System (ADS)

    Schewski, M.; Macke, A.

    radiative fluxes for 3d clouds appears to be a promis- ing approach.

  18. Magnetic energy flow in the solar wind.

    NASA Technical Reports Server (NTRS)

    Modisette, J. L.

    1972-01-01

    Discussion of the effect of rotation (tangential flow) of the solar wind on the conclusions of Whang (1971) suggesting an increase in the solar wind velocity due to the conversion of magnetic energy to kinetic energy. It is shown that the effect of the rotation of the sun on the magnetic energy flow results in most of the magnetic energy being transported by magnetic shear stress near the sun.

  19. Efforts to Simulate Solar Wind Turbulence

    NASA Technical Reports Server (NTRS)

    Goldstein, Melvyn L.

    2007-01-01

    A three-dimensional integration of the MHD equations in spherical coordinates has been developed that attempts to simulate a variety of solar wind conditions. These include the interaction of Alfven wave packets and the development of a turbulent cascade, the role of the heliospheric current sheet, the role of quasi-two-dimensional fluctuations in determining how magnetic field lines meander throughout the heliosphere, and the role of interstellar pickup ions in perturbing the solar wind in the outer heliosphere.

  20. Quantifying Solar Wind-Polar Cap Interactions

    NASA Astrophysics Data System (ADS)

    Urban, K. D.; Gerrard, A. J.; Lanzerotti, L. J.; Weatherwax, A. T.; Huang, Y.

    2015-12-01

    It is well known that the solar wind is a major driver of ultra-low frequency [ULF] power at ground locations from low to high latitudes. However, due to the scarcity of deep polar cap magnetometer sites, it is not clear when, where, or if this is true deep inside the polar cap on open field lines where interplanetary magnetic field [IMF] ULF waves could possibly be directly detected. Given recent observations of very large Joule heating estimates from DMSP data, together with the large heating reported by the CHAMP satellite, it is important to understand the degree to which ULF waves in the solar wind can directly cause such heating. Using a time series of lagged correlation sequences ("dynamic correlograms") between GSM Bz ULF power (computed via data obtained from NASA's Advanced Composition Explorer [ACE] ahead of Earth in the solar wind) and the horizontal ULF power (H^2=N^2+E^2) from ground-based magnetometers in Earth's southern polar cap, we investigate the direct penetration of ULF waves from the solar wind into the polar ionosphere during a gamut of space weather conditions at a distributed network of Automated Geophysical Observatories [AGOs] in Antarctica. To infer causation, a predicted lag correlation maximum at each time step is computed by simply dividing the associated distance of ACE from Earth by the concurrent bulk solar wind speed. This technique helps parse out direct penetration of solar wind ULF waves from other sources (e.g., via leakage from closed field line resonances due to the bulk solar wind plasma viscously interacting at dawn/dusk flanks inducing Kelvin-Helmholtz instabilities [KHI] or compressional modes induced by impulses in solar wind dynamic pressure). The identified direct-penetrating ULF waves are related to the DMSP-derived Poynting fluxes by regression analysis, and conclusions are drawn for the importance of the ULF source for the measured heating.

  1. The interaction of the solar wind with the interstellar medium

    NASA Technical Reports Server (NTRS)

    Axford, W. I.

    1972-01-01

    The expected characteristics of the solar wind, extrapolated from the vicinity of the earth are described. Several models are examined for the interaction of the solar wind with the interstellar plasma and magnetic field. Various aspects of the penetration of neutral interstellar gas into the solar wind are considered. The dynamic effects of the neutral gas on the solar wind are described. Problems associated with the interaction of cosmic rays with the solar wind are discussed.

  2. Correlations between neutral and ionized solar wind

    NASA Astrophysics Data System (ADS)

    Pilkerton, B. M.; Collier, M. R.; Moore, T. E.

    We report results of a statistical study correlating ionized solar wind (ISW) fluxes observed by ACE during late 2000 and throughout 2001 with neutral solar wind (NSW) fluxes observed by IMAGE/LENA over the same period. The average correlation coefficient between the neutral and ionized solar wind is 0.66 with correlations greater than 0.80 occurring about 29% of the time. Correlations appear to be driven by high solar wind flux variability, similar to results obtained by in situ multi-spacecraft correlation studies. In this study, however, IMAGE remains inside the magnetosphere on over 95% of its orbits. As a function of day of year, or equivalently ecliptic longitude, the slope of the relationship between the neutral solar wind flux and the ionized solar wind flux shows an enhancement near the upstream direction, but the symmetry point appears shifted toward higher ecliptic longitudes than the interstellar neutral (ISN) flow direction by about 20°. The estimated peak interstellar neutral upstream density inside of 1 AU is about 7 × 10 -3 cm -3.

  3. BMSW - Fast solar wind monitor in operation

    NASA Astrophysics Data System (ADS)

    Safrankova, J.; Nemecek, Z.; Prech, L.; Zastenker, G. N.

    2012-04-01

    The Spektr-R spacecraft was launched on a Zenit-3F rocket into the Earth orbit with a perigee of 10,000 kilometers and apogee of 390,000 km on July 18, 2011. The spacecraft operational lifetime would exceed five years. The main task of the mission is investigation of distant sources of electromagnetic emissions but, as a supporting measurement, the spacecraft carries a complex of the devices for solar wind monitoring. The main task of the solar wind monitor (BMSW) is to provide the fast measurements of the solar wind density, velocity, and temperature with a time resolution of 32 ms. Such time resolution was obtained using simultaneous measurements of several Faraday cups oriented permanently approximately in the solar wind direction. We describe briefly basic principles of the measurements, bring several examples of observations that demonstrate necessity of fast measurements for a better understanding of solar wind processes and compare BMSW observations with other available solar wind spacecraft. We explain the data strategy and processing and present the data products that are already available for the broad scientific community via web page of the project.

  4. Origin of the Ubiquitous Fast Solar Wind

    NASA Technical Reports Server (NTRS)

    Habbal, S. R.; Woo, R.; Fineschi, S.; O'Neal, R.; Kohl, J.; Noci, G.

    1997-01-01

    The solar wind is a direct manifestation of the coronal heating processes which continue to elude us. For over three decades, observations in interplanetary space have identified two types of wind: a slow component with highly variable physical properties also characterized by speeds typically beow 500 kn/s, and a much less variable fast wind flowing on average at 750 km/s1.

  5. Sulfur abundances in the solar wind measured by SWICS on Ulysses. [Solar Wind Ion Composition Spectrometer

    NASA Technical Reports Server (NTRS)

    Shafer, C. M.; Gloeckler, G.; Galvin, A. B.; Ipavich, F. M.; Geiss, J.; Von Steiger, R.; Ogilvie, K.

    1993-01-01

    One of the nine experiments on Ulysses (launched October, 1990), the Solar Wind Ion Composition Spectrometer, utilizes an energy per charge deflection system along with time of flight technology to uniquely determine the mass and mass per charge of solar wind particles. Thus the composition of various solar wind types can be analyzed. Using the SWICS data accumulated during the in-ecliptic phase of the mission, we have determined the sulfur abundance, relative to silicon, in two different types of solar wind: transient and coronal hole associated flows. Sulfur is of extreme interest because it is one of the few elements that lies in the transitional region of the FIP-dependent relative abundance enrichment function, observed for solar energetic particles and some types of solar wind flows.

  6. 3D Model of Slip-Running Reconnection on Solar Sigmoidal Regions

    NASA Astrophysics Data System (ADS)

    Douglas, B.; Savcheva, A. S.; DeLuca, E. E.

    2015-12-01

    The structure of energy storing magnetic field lines on the Sun is very twisted and contorted. Some of the twist arises from photospheric foot point motion and some is due to currents carried into the corona as fields emerge. The stability of a region depends on both the energy stored (so-called "free" energy) and on the structure of the surrounding nearly potential fields. Free energy is usually contained in these S-shaped regions called sigmoids on the solar corona. The only way to reach lower energy state is to release this free energy, by changing its connectivity. This change in connectivity leads to flares and coronal mass ejections (CMEs) that can affect environments of nearby planets. For this project, we focus on a special kind of connectivity change called slip-running reconnection to create 3D numerical models of flare-producing magnetic fields. By comparing these numerical models to observational data from Atmospheric Imaging Assembly (AIA), we will be able to better explain the evolution of sigmoidal flares from active regions. We are studying a flare from Dudik et al 2014 paper (2012 July 12), and a flare from 2015 June 14. Using the Coronal Modeling System (CMS) software, we read the photospheric magnetogram for the specified date and time, compute the potential field, setup the 3D flux rope path, and then relax this flux rope over 60,000 iterations to create a nonlinear force-free field (NLFFF). Using these relaxed models we find the best-fit loops surrounding the flux rope. We then compare these models to the observations in AIA. We compare the magnetic field structure in our models with the observed slipping. For regions near our inserted flux rope, our models successfully correlate with this observation. Further modeling is required, but these initial results suggest that NLFFF modeling may be able to capture realistic 3-D magnetic structures associated with slipping reconnection.

  7. Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions

    PubMed Central

    Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; Lin, Oliver; Huang, Chih-Meng; Limsakoune, Vipawee; Chou, Yi-Chia; Yang, Yang; Tung, Vincent

    2016-01-01

    The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape. PMID:27924857

  8. Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions

    NASA Astrophysics Data System (ADS)

    Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; Lin, Oliver; Huang, Chih-Meng; Limsakoune, Vipawee; Chou, Yi-Chia; Yang, Yang; Tung, Vincent

    2016-12-01

    The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.

  9. Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions.

    PubMed

    Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; Lin, Oliver; Huang, Chih-Meng; Limsakoune, Vipawee; Chou, Yi-Chia; Yang, Yang; Tung, Vincent

    2016-12-07

    The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.

  10. A Comparison of the Propagated Solar Wind with Near-Earth Solar Wind Observations

    NASA Astrophysics Data System (ADS)

    Hsu, T. S.

    2015-12-01

    Magneotospheric dynamics are primarily controlled by the solar wind and its interplanetary magnetic field (IMF). Majority of the magnetospheric studies relied on observation of the solar wind frequently taken as far away as the L1 Lagrange point approximately 230 RE upstream. The quality of the empirical or theoretical modeling depends on how accurately the solar wind observation at L1 can be propagated to the magnetosphere and drives the magnetospheric dynamics. It has been more than two decades that researchers seek to determine the structures and evolution of the solar wind observationally in order to characterize the propagated solar wind parcels that interact with the Earth. Russell et al. [1980] used solar wind data at the Earth and L1 without considering the type of solar wind structures and found that the Bz correlations varied from 0.0 to 1.0. Although the most probable correlation was 0.85, half of the time the correlation was less than 0.5. The scale of IMF correlations was reexamined by Collier et al. [1998] using data from Wind and IMP 8. It should be noted that Collier et al. [1998] examined data during solar minimum and Russell et al. [1980] examined data during solar maximum. The scales of solar wind plasma and magnetic field were further examined by Richardson and Paularena [2001]. The found that the transverse scale for a decrease in density correlation by 0.1 is 120 Re and for velocity about 70 Re. In contrast the transverse scales for the components of the IMF are about 50 Re. Using ISEE 2 and IMP8 from 1978 to 1985, Hsu and McPherron [2009] found that a small transvers IMF structure of about 15 Re can occur only about 5%~13% . Most of the recent studies examining Sun-Earth coupling using OMNI solar data which is propagated to the Earth-Sun line by a method based upon minimum variance analysis [Weimer et al., 2003; Bargatze et al., 2005]. The important question of how often a near-earth IMF structure is absent from the propagated solar wind and

  11. The Genesis Solar Wind Sample Return Mission

    NASA Technical Reports Server (NTRS)

    Wiens, Roger C.; Burnett, Donald S.; Neugebauer, Marcia; Sasaki, Chester; Sevilla, Donald; Stansbery, Eileen; Clark, Ben; Smith, Nick; Oldham, Lloyd

    1990-01-01

    The Genesis spacecraft was launched on August 8 from Cape Canaveral on a journey to become the first spacecraft to return from interplanetary space. The fifth in NASA's line of low-cost Discovery-class missions, its goal is to collect samples of solar wind and return them to Earth for detailed isotopic and elemental analysis. The spacecraft is to collect solar wind for over two years, while circling the L1 point 1.5 million km sunward of the earth, before heading back for a capsule-style re-entry in September, 2004. After parachute deployment, a mid-air helicopter recovery will be used to avoid a hard landing. The mission has been in the planning stages for over ten years. Its cost, including development, mission operations, and sample analysis, is approximately $209M. The Genesis science team, headed by principal investigator Donald Burnett of Caltech, consists of approximately 20 co-investigators from universities and science centers around the country and internationally. The spacecraft consists of a relatively flat spacecraft bus containing most of the subsystem components, situated below a sample return capsule (SRC) which holds the solar-wind collection substrates and an electrostatic solar wind concentrator. Some of the collectors are exposed throughout the collection period, for a sample of bulk solar wind, while others are exposed only to certain solar wind regimes, or types of flow. Ion and electron spectrometers feed raw data to the spacecraft control and data-handling (C&DH) unit, which determines ion moments and electron flux geometries in real time. An algorithm is used to robotically decide between interstream (IS), coronal hole (CH), and coronal mass ejection (CME) regimes, and to control deployment of the proper arrays to sample these wind regimes independently. This is the first time such a solar-wind decision algorithm has been used on board a spacecraft.

  12. Mars ionospheric response to solar wind variability

    NASA Astrophysics Data System (ADS)

    Opgenoorth, H. J.; Andrews, D. J.; Fränz, M.; Lester, M.; Edberg, N. J. T.; Morgan, D.; Duru, F.; Witasse, O.; Williams, A. O.

    2013-10-01

    planets with induced magnetospheres, the coupling between the ionosphere, the weak draped magnetosphere, and the solar wind is very direct in comparison to Earth. The weak induced magnetosphere itself is created by the prevailing Solar wind conditions and therefore in its shape and strength dynamically depending on it. In early 2010, Mars was located behind Earth in the Solar wind; thus, we can use coordinated data from multiple near-Earth spacecraft (Stereo, Wind) to evaluate what kind of Solar wind disturbances have passed by Earth and might consecutively hit Mars, and when. We employ plasma data from the ESA Mars-Express mission, the ASPERA-3 particle instrument, and the MARSIS Active Ionospheric Sounder (AIS) to investigate, for a number of isolated events in March and April 2010, how the ionosphere and the induced magnetosphere at Mars develop and decay in response to Solar wind variability in the magnetic field, density, and velocity. In a dedicated campaign mode, we use frequent long-duration MARSIS AIS operations for several consecutive orbits, to monitor for the first time the long-term development of the Martian plasma environment during solar wind disturbances. We find that the magnetosphere and ionosphere of Mars can become considerably compressed by solar wind dynamic pressure variations, which usually are also associated with changes in the magnetic draping of the interplanetary magnetic field around the planet. These are typically associated with corotating interaction regions and coronal mass ejections, and can last for several days. During such episodes of compression, we see signatures of increased plasma transport over the terminator and enhanced ion outflow from the upper atmosphere.

  13. The Genesis Mission Solar Wind Collection: Solar-Wind Statistics over the Period of Collection

    NASA Technical Reports Server (NTRS)

    Barraclough, B. L.; Wiens, R. C.; Steinberg, J. E.; Reisenfeld, D. B.; Neugebauer, M.; Burnett, D. S.; Gosling, J.; Bremmer, R. R.

    2004-01-01

    The NASA Genesis spacecraft was launched August 8, 2001 on a mission to collect samples of solar wind for 2 years and return them to earth September 8, 2004. Detailed analyses of the solar wind ions implanted into high-purity collection substrates will be carried out using various mass spectrometry techniques. These analyses are expected to determine key isotopic ratios and elemental abundances in the solar wind, and by extension, in the solar photosphere. Further, the photospheric composition is thought to be representative of the solar nebula with a few exceptions, so that the Genesis mission will provide a baseline for the average solar nebula composition with which to compare present-day compositions of planets, meteorites, and asteroids. The collection of solar wind samples is almost complete. Collection began for most substrates in early December, 2001, and is scheduled to be complete on April 2 of this year. It is critical to understand the solar-wind conditions during the collection phase of the mission. For this reason, plasma ion and electron spectrometers are continuously monitoring the solar wind proton density, velocity, temperature, the alpha/proton ratio, and angular distribution of suprathermal electrons. Here we report on the solar-wind conditions as observed by these in-situ instruments during the first half of the collection phase of the mission, from December, 2001 to present.

  14. Dynamics of solar wind speed: Cycle 23

    NASA Astrophysics Data System (ADS)

    Sarkar, Tushnik; Khondekar, Mofazzal H.; Banerjee, Subrata

    2017-04-01

    A statistical signal processing approach has been made to study the dynamics of the speed of steady flow of hot plasma from the corona of sun known as solar wind generated in Solar Cycle 23. A long time series of solar wind speed of length 2492 days from 1st Jan, 1997 to 28th October, 2003 collected from Coordinated Heliospheric Observations (COHO) data base at NASA's National Space Science Data Center (NSSDC) is investigated for this purpose. Detection of nonlinearity and chaos in dynamics of solar wind speed is the prime objective of this work. In the present analysis delay vector variance (DVV) method is used to detect the existence of nonlinearity within the dynamics of solar wind speed. To explore the signature of the chaos in it multiple statistical methodologies like '0-1' test, the correlation dimension analysis, computation of Information Entropy of the time series and Largest Lyapunov Exponent method have been applied. It has been observed that though the coronal plasma i.e. solar wind flow rate has a nonlinear dynamics but without any chaos. The absence of chaos indicates a probable regular behaviour of the series. The unit magnitude of the Correlation dimension indicates the presence of the deterministic component of the series. Embedding Dimension obtained argues that the deterministic component has dimension of six. The nearly zero value of the Lyapunov exponent claims that the system is conservative and exhibits Lyapunov stability. These revelations establish that not only the solar wind speed alone but the solar wind-magnetosphere coupling is also contributing towards the complexity of the magnetospheric plasma dynamics.

  15. Data-driven modeling of the solar wind from 1 Rs to 1 AU

    NASA Astrophysics Data System (ADS)

    Feng, Xueshang; Ma, Xiaopeng; Xiang, Changqing

    2015-12-01

    We present here a time-dependent three-dimensional magnetohydrodynamic (MHD) solar wind simulation from the solar surface to the Earth's orbit driven by time-varying line-of-sight solar magnetic field data. The simulation is based on the three-dimensional (3-D) solar-interplanetary (SIP) adaptive mesh refinement (AMR) space-time conservation element and solution element (CESE) MHD (SIP-AMR-CESE MHD) model. In this simulation, we first achieve the initial solar wind background with the time-relaxation method by inputting a potential field obtained from the synoptic photospheric magnetic field and then generate the time-evolving solar wind by advancing the initial 3-D solar wind background with continuously varying photospheric magnetic field. The model updates the inner boundary conditions by using the projected normal characteristic method, inputting the high-cadence photospheric magnetic field data corrected by solar differential rotation, and limiting the mass flux escaping from the solar photosphere. We investigate the solar wind evolution from 1 July to 11 August 2008 with the model driven by the consecutive synoptic maps from the Global Oscillation Network Group. We compare the numerical results with the previous studies on the solar wind, the solar coronal observations from the Extreme ultraviolet Imaging Telescope board on Solar and Heliospheric Observatory, and the measurements from OMNI at 1 astronomical unit (AU). Comparisons show that the present data-driven MHD model's results have overall good agreement with the large-scale dynamical coronal and interplanetary structures, including the sizes and distributions of the coronal holes, the positions and shapes of the streamer belts, the heliocentric distances of the Alfvénic surface, and the transitions of the solar wind speeds. However, the model fails to capture the small-sized equatorial holes, and the modeled solar wind near 1 AU has a somewhat higher density and weaker magnetic field strength than

  16. 3D Concrete Printing Concept Could Solve Tall-Wind Dilemma

    ScienceCinema

    Cotrell, Jason; Jenne, Scott; Butterfield, Sandy

    2017-01-06

    When building a wind turbine, you want to make it as tall as possible to capture stronger, faster winds aloft. But taller tower bases become too large to be transported over the road—a constraint that has kept average U.S. wind turbine heights at 80 meters for the last 10 years. A Lab-Corps project undertaken by the National Renewable Energy Laboratory has found a potential solution: automated concrete manufacturing.

  17. 3D Concrete Printing Concept Could Solve Tall-Wind Dilemma

    SciTech Connect

    Cotrell, Jason; Jenne, Scott; Butterfield, Sandy

    2016-12-29

    When building a wind turbine, you want to make it as tall as possible to capture stronger, faster winds aloft. But taller tower bases become too large to be transported over the road—a constraint that has kept average U.S. wind turbine heights at 80 meters for the last 10 years. A Lab-Corps project undertaken by the National Renewable Energy Laboratory has found a potential solution: automated concrete manufacturing.

  18. Are There Natural Categories of Solar Wind?

    NASA Astrophysics Data System (ADS)

    Roberts, D. A.; Sipes, T.; Karimabadi, H.

    2014-12-01

    What seem to be the most obvious categories of solar wind, such as fast and slow, often turn out to be difficult to pin down on closer examination. For example, while slow winds tend to be dense and nonAlfvenic, there are significant exceptions, with some slow winds being not only very Alfvenic but also exhibiting many fast wind traits. Here we use "unsupervised" data mining to look for "natural" solar wind types. We use a set of variables to represent the state of the system and apply what are now standard algorithms to look for natural clustering of these variables. We have done this process for the solar wind density, speed, a carbon charge state ratio (6+ to 5+), the cross-helicity, and the "residual energy." When using the first three of these, we find two groups that tend to be slow and fast, but with the boundary between the groups that is a combination of speed and density. When all five variables are used, the best characterization of the states is as three basic groups in the cross-helicity vs residual energy space, i.e., in terms of "turbulence" measures rather than simple parameters. The three-variable case is largely but not completely reproduced in its subspace. We will suggest what the results could mean for the understanding of issues such as solar wind acceleration.

  19. The GENESIS Mission Solar Wind Samples: Collection Times, Estimated Fluences, and Solar-Wind Conditions

    NASA Astrophysics Data System (ADS)

    Reisenfeld, D. B.; Wiens, R. C.; Barraclough, B. L.; Steinberg, J. E.; Dekoning, C.; Zurbuchen, T. H.; Burnett, D. S.

    2005-03-01

    We have correlated the GENESIS sample collection times for the different solar-wind regimes with compositional data from GENESIS/GIM and ACE/SWICS instruments. We discuss GENESIS regime selection and new results in solar-wind elemental fractionation.

  20. 3D reconstruction and particle acceleration properties of Coronal Shock Waves During Powerful Solar Particle Events

    NASA Astrophysics Data System (ADS)

    Plotnikov, Illya; Vourlidas, Angelos; Tylka, Allan J.; Pinto, Rui; Rouillard, Alexis; Tirole, Margot

    2016-07-01

    Identifying the physical mechanisms that produce the most energetic particles is a long-standing observational and theoretical challenge in astrophysics. Strong pressure waves have been proposed as efficient accelerators both in the solar and astrophysical contexts via various mechanisms such as diffusive-shock/shock-drift acceleration and betatron effects. In diffusive-shock acceleration, the efficacy of the process relies on shock waves being super-critical or moving several times faster than the characteristic speed of the medium they propagate through (a high Alfven Mach number) and on the orientation of the magnetic field upstream of the shock front. High-cadence, multipoint imaging using the NASA STEREO, SOHO and SDO spacecrafts now permits the 3-D reconstruction of pressure waves formed during the eruption of coronal mass ejections. Using these unprecedented capabilities, some recent studies have provided new insights on the timing and longitudinal extent of solar energetic particles, including the first derivations of the time-dependent 3-dimensional distribution of the expansion speed and Mach numbers of coronal shock waves. We will review these recent developments by focusing on particle events that occurred between 2011 and 2015. These new techniques also provide the opportunity to investigate the enigmatic long-duration gamma ray events.

  1. 3D optical simulation formalism OPTOS for textured silicon solar cells.

    PubMed

    Tucher, Nico; Eisenlohr, Johannes; Kiefel, Peter; Höhn, Oliver; Hauser, Hubert; Peters, Marius; Müller, Claas; Goldschmidt, Jan Christoph; Bläsi, Benedikt

    2015-11-30

    In this paper we introduce the three-dimensional formulation of the OPTOS formalism, a matrix-based method that allows for the efficient simulation of non-coherent light propagation and absorption in thick textured sheets. As application examples, we calculate the absorptance of solar cells featuring textures on front and rear side with different feature sizes operating in different optical regimes. A discretization of polar and azimuth angle enables a three-dimensional description of systems with arbitrary surface textures. We present redistribution matrices for 3D surface textures, including pyramidal textures, binary crossed gratings and a Lambertian scatterer. The results of the OPTOS simulations for silicon sheets with different combinations of these surfaces are in accordance with both optical measurements and results based on established simulation methods like ray tracing. Using OPTOS, we show that the integration of a diffractive grating at the rear side of a silicon solar cell featuring a pyramidal front side results in absorption close to the Yablonovitch Limit enhancing the photocurrent density by 0.6 mA/cm2 for a 200 µm thick cell.

  2. Improving organic tandem solar cells based on water-processed nanoparticles by quantitative 3D nanoimaging.

    PubMed

    Pedersen, E B L; Angmo, D; Dam, H F; Thydén, K T S; Andersen, T R; Skjønsfjell, E T B; Krebs, F C; Holler, M; Diaz, A; Guizar-Sicairos, M; Breiby, D W; Andreasen, J W

    2015-08-28

    Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing industry, which has reduced the use of organic solvents since the 1980s. Through ptychographic X-ray computed tomography (PXCT), we image quantitatively a roll-to-roll coated photovoltaic tandem stack consisting of one bulk heterojunction active layer and one Landfester particle active layer. We extract the layered morphology with structural and density information including the porosity present in the various layers and the silver electrode with high resolution in 3D. The Landfester particle layer is found to have an undesired morphology with negatively correlated top- and bottom interfaces, wide thickness distribution and only partial surface coverage causing electric short circuits through the layer. By top coating a polymer material onto the Landfester nanoparticles we eliminate the structural defects of the layer such as porosity and roughness, and achieve the increased performance larger than 1 V expected for a tandem cell. This study highlights that quantitative imaging of weakly scattering stacked layers of organic materials has become feasible by PXCT, and that this information cannot be obtained by other methods. In the present study, this technique specifically reveals the need to improve the coatability and layer formation of Landfester nanoparticles, thus allowing improved solar cells to be produced.

  3. Solar wind origin in coronal funnels.

    PubMed

    Tu, Chuan-Yi; Zhou, Cheng; Marsch, Eckart; Xia, Li-Dong; Zhao, Liang; Wang, Jing-Xiu; Wilhelm, Klaus

    2005-04-22

    The origin of the solar wind in solar coronal holes has long been unclear. We establish that the solar wind starts flowing out of the corona at heights above the photosphere between 5 megameters and 20 megameters in magnetic funnels. This result is obtained by a correlation of the Doppler-velocity and radiance maps of spectral lines emitted by various ions with the force-free magnetic field as extrapolated from photospheric magnetograms to different altitudes. Specifically, we find that Ne7+ ions mostly radiate around 20 megameters, where they have outflow speeds of about 10 kilometers per second, whereas C3+ ions with no average flow speed mainly radiate around 5 megameters. Based on these results, a model for understanding the solar wind origin is suggested.

  4. PULSED ALFVEN WAVES IN THE SOLAR WIND

    SciTech Connect

    Gosling, J. T.; Tian, H.; Phan, T. D.

    2011-08-20

    Using 3 s plasma and magnetic field data from the Wind spacecraft located in the solar wind well upstream from Earth, we report observations of isolated, pulse-like Alfvenic disturbances in the solar wind. These isolated events are characterized by roughly plane-polarized rotations in the solar wind magnetic field and velocity vectors away from the directions of the underlying field and velocity and then back again. They pass over Wind on timescales ranging from seconds to several minutes. These isolated, pulsed Alfven waves are pervasive; we have identified 175 such events over the full range of solar wind speeds (320-550 km s{sup -1}) observed in a randomly chosen 10 day interval. The large majority of these events are propagating away from the Sun in the solar wind rest frame. Maximum field rotations in the interval studied ranged from 6 Degree-Sign to 109 Degree-Sign . Similar to most Alfvenic fluctuations in the solar wind at 1 AU, the observed changes in velocity are typically less than that predicted for pure Alfven waves (Alfvenicity ranged from 0.28 to 0.93). Most of the events are associated with small enhancements or depressions in magnetic field strength and small changes in proton number density and/or temperature. The pulse-like and roughly symmetric nature of the magnetic field and velocity rotations in these events suggests that these Alfvenic disturbances are not evolving when observed. They thus appear to be, and probably are, solitary waves. It is presently uncertain how these waves originate, although they may evolve out of Alfvenic turbulence.

  5. MHD simulations for investigating interaction processes between a CME and ambient solar wind

    NASA Astrophysics Data System (ADS)

    An, Junmo; Magara, Tetsuya

    2016-05-01

    The interaction between coronal mass ejections (CMEs) and ambient solar winds is one of the important issues of space weather because it affects the trajectory of a flying CME, which determines whether the CME hits the Earth and produces geomagnetic disturbances or not. In this study, two-step 3D magnetohydrodynamic (MHD) simulations including a spheromak-type CME and an ambient solar wind are performed to investigate their interaction processes such as deflection and rotation of a CME. We perform the 1st-step MHD simulation using averaged surface magnetic field data to construct a steady state with an ambient solar wind. A spheromak-type CME is then injected through the solar surface, and subsequent evolution is reproduced by performing the 2nd-step MHD simulation. We discuss key parameters that characterize interaction processes between a CME and ambient solar wind.

  6. Evidence of active region imprints on the solar wind structure

    NASA Technical Reports Server (NTRS)

    Hick, P.; Jackson, B. V.

    1995-01-01

    A common descriptive framework for discussing the solar wind structure in the inner heliosphere uses the global magnetic field as a reference: low density, high velocity solar wind emanates from open magnetic fields, with high density, low speed solar wind flowing outward near the current sheet. In this picture, active regions, underlying closed magnetic field structures in the streamer belt, leave little or no imprint on the solar wind. We present evidence from interplanetary scintillation measurements of the 'disturbance factor' g that active regions play a role in modulating the solar wind and possibly contribute to the solar wind mass output. Hence we find that the traditional view of the solar wind, though useful in understanding many features of solar wind structure, is oversimplified and possibly neglects important aspects of solar wind dynamics

  7. Solar and Solar Wind Disturbance Predictions

    DTIC Science & Technology

    2007-10-11

    PPS), Journal of Atmospheric and Solar - Terrestrial Physics , 69, 43, 2007. Lockwood, M., R. Stamper, and M.N. Wild, A...doi:10.1029/2006JA011678, 2006. Kahler, S.W., E.W. Cliver, and A.G. Ling, Validating the proton prediction system (PPS), Journal of Atmospheric and Solar - Terrestrial Physics , 69

  8. A tetraphenylethylene core-based 3D structure small molecular acceptor enabling efficient non-fullerene organic solar cells.

    PubMed

    Liu, Yuhang; Mu, Cheng; Jiang, Kui; Zhao, Jingbo; Li, Yunke; Zhang, Lu; Li, Zhengke; Lai, Joshua Yuk Lin; Hu, Huawei; Ma, Tingxuan; Hu, Rongrong; Yu, Demei; Huang, Xuhui; Tang, Ben Zhong; Yan, He

    2015-02-01

    A tetraphenylethylene core-based small molecular acceptor with a unique 3D molecular structure is developed. Bulk-heterojunction blend films with a small feature size (≈20 nm) are obtained, which lead to non-fullerene organic solar cells (OSCs) with 5.5% power conversion efficiency. The work provides a new molecular design approach to efficient non-fullerene OSCs based on 3D-structured small-molecule acceptors.

  9. SOLAR METALLICITY DERIVED FROM IN SITU SOLAR WIND COMPOSITION

    SciTech Connect

    Von Steiger, R.; Zurbuchen, T. H. E-mail: thomasz@umich.edu

    2016-01-01

    We use recently released solar wind compositional data to determine the metallicity of the Sun—the fraction per unit mass that is composed of elements heavier than He. We focus on a present-day solar sample available to us, which is the least fractionated solar wind from coronal holes near the poles of the Sun. Using these data, we derive a metallicity of Z = 0.0196 ± 0.0014, which is significantly larger than recent published values based on photospheric spectroscopy, but consistent with results from helioseismology.

  10. 2D/3D perovskite hybrids as moisture-tolerant and efficient light absorbers for solar cells.

    PubMed

    Ma, Chaoyan; Leng, Chongqian; Ji, Yixiong; Wei, Xingzhan; Sun, Kuan; Tang, Linlong; Yang, Jun; Luo, Wei; Li, Chaolong; Deng, Yunsheng; Feng, Shuanglong; Shen, Jun; Lu, Shirong; Du, Chunlei; Shi, Haofei

    2016-11-03

    The lifetime and power conversion efficiency are the key issues for the commercialization of perovskite solar cells (PSCs). In this paper, the development of 2D/3D perovskite hybrids (CA2PbI4/MAPbIxCl3-x) was firstly demonstrated to be a reliable method to combine their advantages, and provided a new concept for achieving both stable and efficient PSCs through the hybridization of perovskites. 2D/3D perovskite hybrids afforded significantly-improved moisture stability of films and devices without encapsulation in a high humidity of 63 ± 5%, as compared with the 3D perovskite (MAPbIxCl3-x). The 2D/3D perovskite-hybrid film did not undergo any degradation after 40 days, while the 3D perovskite decomposed completely under the same conditions after 8 days. The 2D/3D perovskite-hybrid device maintained 54% of the original efficiency after 220 hours, whereas the 3D perovskite device lost all the efficiency within only 50 hours. Moreover, the 2D/3D perovskite hybrid achieved comparable device performances (PCE: 13.86%) to the 3D perovskite (PCE: 13.12%) after the optimization of device fabrication conditions.

  11. HyperCube: a hyperspectral CubeSat constellation for measurements of 3D winds

    NASA Astrophysics Data System (ADS)

    Glumb, Ronald; Lapsley, Michael; Luce, Scott; Déry, Jean-Philippe; Scott, Deron; Nielsen, Tim

    2016-09-01

    Global measurements of vertically resolved atmospheric wind profiles offer the potential for improved weather forecasts and superior predictions of atmospheric wind patterns. Harris' HyperCube constellation of twelve 6U hyperspectral CubeSats can provide measurements of global tropospheric wind profiles from space at very low cost. It is a commercially funded enterprise in which the data from the satellites is provided to users on a subscription basis. This requires that the design of each satellite be optimized for minimum cost, yet with a reasonably long service life. This paper will focus on the design, operations, and projected performance of the HyperCube system.

  12. Laboratory Facility for Simulating Solar Wind Sails

    SciTech Connect

    Funaki, Ikkoh; Ayabe, Tomohiro; Horisawa, Hideyuki; Yamakawa, Hiroshi

    2008-12-31

    Magnetic sail (MagSail) is a deep space propulsion system, in which an artificial magnetic cavity captures the energy of the solar wind to propel a spacecraft in the direction leaving the sun. For a scale-model experiment of the plasma flow of MagSail, we employed a magnetoplasmadynamic arcjet as a solar wind simulator. It is observed that a plasma flow from the solar wind simulator reaches a quasi-steady state of about 0.8 ms duration after a transient phase when initiating the discharge. During this initial phase of the discharge, a blast-wave was observed to develop radially in a vacuum chamber. When a solenoidal coil (MagSail scale model) is immersed into the quasi-steady flow where the velocity is 45 km/s, and the number density is 10{sup 19} m-3, a bow shock as well as a magnetic cavity were formed in front of the coil. As a result of the interaction between the plasma flow and the magnetic cavity, the momentum of the simulated solar wind is decreased, and it is found from the thrust measurement that the solar wind momentum is transferred to the coil simulating MagSail.

  13. Ancient solar wind in lunar microbreccias

    NASA Technical Reports Server (NTRS)

    Thiemens, M. H.; Clayton, R. N.

    1980-01-01

    Possible components of the ancient solar wind, particularly the N-15/N-14 ratio, are investigated on the basis of lunar microbreccia studies. Nitrogen contents and isotope ratios were determined for Apollo 11 and 15 microbreccia samples by means of vacuum pyrolysis techniques. The Apollo 11 soil breccias, which had been closed to the addition of recent solar wind due to their compaction, are found to contain the lowest N-15/N-14 ratios yet reported for the solar wind, extending the range of variation of the ratio to between a delta N-15 of -190% in the past to +120% at present. Nitrogen isotope analysis of the Apollo 15 drill core, which had undergone two episodes of solar wind exposure, also support the secular variation in the N-15 content of the solar wind, which is attributed to spallation reactions in the sun. The formation of the breccias at the Apollo 11 and 15 sites is discussed on the basis of the observed nitrogen systematics, and differences between N-15 and Ne-21 cosmic ray exposure ages implied are attributed to the diffusive loss of neon from lunar soils.

  14. Mars Ionospheric Response to Solar Wind Variability

    NASA Astrophysics Data System (ADS)

    Opgenoorth, H. J.; Edberg, N.; Lester, M.; Williams, A.; Fränz, M.; Witasse, O.; Duru, F.; Morgan, D.

    2011-10-01

    At planets with induced magnetospheres the coupling between the ionosphere, the small draped magnetosphere and the solar wind is in a way much more direct than at Earth. On the other hand it is also much more complicated as the magnetosphere itself is created and in its total shape and strength dynamically depending on the prevailing Solar wind conditions. In early 2010 Mars was located behind Earth in the Solar wind. In this study we have utilized coordinated data from multiple near-Earth spacecraft (Stereo, ACE, Cluster, and even Earth groundbased data) to evaluate what kind of Solar wind disturbances have passed by Earth and might hit Mars consecutively (and when). We use plasma data from the ESA Mars- Express mission (mainly from the ASPERA particle instrument and the MARSIS topside ionospheric sounder) to investigate what kind of ionospheric and magnetospheric response is triggered at Mars in response to Solar wind variability in the magnetic field, density and velocity for a number of isolated events in March and April 2010.

  15. 3D radiative transfer simulations of Eta Carinae's inner colliding winds - I. Ionization structure of helium at apastron

    NASA Astrophysics Data System (ADS)

    Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Paardekooper, J.-P.; Gull, T. R.

    2015-03-01

    The highly eccentric binary system Eta Carinae (η Car) shows numerous time-variable emission and absorption features. These observational signatures are the result of interactions between the complex three-dimensional (3D) wind-wind collision regions and photoionization by the luminous stars. Specifically, helium presents several interesting spectral features that provide important clues on the geometry and physical proprieties of the system and the individual stars. We use the SIMPLEX algorithm to post-process 3D smoothed particle hydrodynamics simulation output of the interacting winds in η Car in order to obtain the fractions of ionized helium assuming three different primary star (ηA) mass-loss rates. The resultant ionization maps constrain the regions where helium is singly- and doubly-ionized. We find that reducing ηA's mass-loss rate (dot{M}_{η A}) increases the volume of He+. Lowering dot{M}_{η A} produces large variations in the volume of He+ in the pre-shock ηA wind on the periastron side of the system. Our results show that binary orientations in which apastron is on our side of the system are more consistent with available observations. We suggest that small variations in dot{M}_{η A} might explain the observed increase in He I absorption in recent decades, although numerous questions regarding this scenario remain open. We also propose that the absence of broad He I lines in the spectra of η Car between its 1890's eruption and ˜1944 might be explained by ηB's He0+-ionizing photons not being able to penetrate the wind-wind interaction region, due to a higher dot{M}_{η A} at that time (by a factor ≳2, compared to the present value).

  16. IMPROVED WIND AND TURBULENCE MEASUREMENTS USING A LOW-COST 3-D SONIC ANEMOMETER AT A LOW-WIND SITE

    SciTech Connect

    Bowen, B

    2007-05-11

    A year of data from sonic anemometer and mechanical wind sensors was analyzed and compared at a low-wind site. Results indicate that 15-minute average and peak 1-second wind speeds (u) from the sonic agree well with data derived from a co-located cup anemometer over a wide range of speeds. Wind direction data derived from the sonic also agree closely with those from a wind vane except for very low wind speeds. Values of standard deviation of longitudinal wind speed ({sigma}{sub u}) and wind direction fluctuations ({delta}{sub {theta}}) from the sonic and mechanical sensors agree well for times with u > 2 ms{sup -1} but show significant differences with lower u values. The most significant differences are associated with the standard deviation of vertical wind fluctuations ({sigma}{sub w}): the co-located vertical propeller anemometer yields values increasingly less than those measured by the sonic anemometer as u decreases from 2.5 approaching 0 ms{sup -1}. The combination of u over-estimation and under-estimation of {sigma}{sub w} from the mechanical sensors at low wind speeds causes considerable under-estimation of the standard deviation of vertical wind angle fluctuations ({sigma}{sub {phi}}), an indicator of vertical dispersion. Calculations of {sigma}{sub {phi}} from sonic anemometer measurements are typically 5{sup o} to 10{sup o} higher when the mechanical instruments indicate that {sigma}{sub {phi}} < 5{sup o} or so. The errors in both the propeller anemometer and cup anemometer, caused by their inability to respond to higher frequency (smaller scale) turbulent fluctuations, can therefore lead to large (factors of 2 to 10 or more) errors in the vertical dispersion during stable conditions with light winds.

  17. Coherent Doppler Wind Lidar Development at NASA Langley Research Center for NASA Space-Based 3-D Winds Mission

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Kavaya, Michael J.; Yu, Jirong; Koch, Grady J.

    2012-01-01

    We review the 20-plus years of pulsed transmit laser development at NASA Langley Research Center (LaRC) to enable a coherent Doppler wind lidar to measure global winds from earth orbit. We briefly also discuss the many other ingredients needed to prepare for this space mission.

  18. Improving organic tandem solar cells based on water-processed nanoparticles by quantitative 3D nanoimaging

    NASA Astrophysics Data System (ADS)

    Pedersen, E. B. L.; Angmo, D.; Dam, H. F.; Thydén, K. T. S.; Andersen, T. R.; Skjønsfjell, E. T. B.; Krebs, F. C.; Holler, M.; Diaz, A.; Guizar-Sicairos, M.; Breiby, D. W.; Andreasen, J. W.

    2015-08-01

    Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing industry, which has reduced the use of organic solvents since the 1980s. Through ptychographic X-ray computed tomography (PXCT), we image quantitatively a roll-to-roll coated photovoltaic tandem stack consisting of one bulk heterojunction active layer and one Landfester particle active layer. We extract the layered morphology with structural and density information including the porosity present in the various layers and the silver electrode with high resolution in 3D. The Landfester particle layer is found to have an undesired morphology with negatively correlated top- and bottom interfaces, wide thickness distribution and only partial surface coverage causing electric short circuits through the layer. By top coating a polymer material onto the Landfester nanoparticles we eliminate the structural defects of the layer such as porosity and roughness, and achieve the increased performance larger than 1 V expected for a tandem cell. This study highlights that quantitative imaging of weakly scattering stacked layers of organic materials has become feasible by PXCT, and that this information cannot be obtained by other methods. In the present study, this technique specifically reveals the need to improve the coatability and layer formation of Landfester nanoparticles, thus allowing improved solar cells to be produced.Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing

  19. Acceleration of the Fast Solar Wind by Solitary Waves in Coronal Holes

    NASA Technical Reports Server (NTRS)

    Ofman, Leon

    2001-01-01

    The purpose of this investigation is to develop a new model for the acceleration of the fast solar wind by nonlinear. time-dependent multidimensional MHD simulations of waves in solar coronal holes. Preliminary computational studies indicate that nonlinear waves are generated in coronal holes by torsional Alfv\\'{e}n waves. These waves in addition to thermal conduction may contribute considerably to the accelerate the solar wind. Specific goals of this proposal are to investigate the generation of nonlinear solitary-like waves and their effect on solar wind acceleration by numerical 2.5D MHD simulation of coronal holes with a broad range of plasma and wave parameters; to study the effect of random disturbances at the base of a solar coronal hole on the fast solar wind acceleration with a more advanced 2.5D MHD model and to compare the results with the available observations; to extend the study to a full 3D MHD simulation of fast solar wind acceleration with a more realistic model of a coronal hole and solar boundary conditions. The ultimate goal of the three year study is to model the, fast solar wind in a coronal hole, based on realistic boundary conditions in a coronal hole near the Sun, and the coronal hole structure (i.e., density, temperature. and magnetic field geometry,) that will become available from the recently launched SOHO spacecraft.

  20. Acceleration of the Fast Solar Wind by Solitary Waves in Coronal Holes

    NASA Technical Reports Server (NTRS)

    Ofman, Leon

    2000-01-01

    The purpose of this investigation is to develop a new model for the acceleration of the fast solar wind by nonlinear, time-dependent multidimensional MHD simulations of waves in solar coronal holes. Preliminary computational studies indicate that solitary-like waves are generated in coronal holes nonlinearly by torsional Alfven waves. These waves in addition to thermal conduction may contribute considerably to the accelerate the solar wind. Specific goals of this proposal are to investigate the generation of nonlinear solitary-like waves and their effect on solar wind acceleration by numerical 2.5D MHD simulation of coronal holes with a broad range of plasma and wave parameters; to study the effect of random disturbances at the base of a solar coronal hole on the fast solar wind acceleration with a more advanced 2.5D MHD model and to compare the results with the available observations; to extend the study to a full 3D MHD simulation of fast solar wind acceleration with a more realistic model of a coronal hole and solar boundary conditions. The ultimate goal of the three year study is to model the fast solar wind in a coronal hole, based on realistic boundary conditions in a coronal hole near the Sun, and the coronal hole structure (i.e., density, temperature, and magnetic field geometry) that will become available from the recently launched SOHO spacecraft.

  1. Simulations of Solar Wind Plasma Flow Around a Simple Solar Sail

    NASA Technical Reports Server (NTRS)

    Garrett, Henry B.; Wang, Joseph

    2004-01-01

    In recent years, a number of solar sail missions of various designs and sizes have been proposed (e.g., Geostorm). Of importance to these missions is the interaction between the ambient solar wind plasma environment and the sail. Assuming a typical 1 AU solar wind environment of 400 km/s velocity, 3.5 cu cm density, ion temperature of approx.10 eV, electron temperature of 40 eV, and an ambient magnetic field strength of 10(exp -4) G, a first order estimate of the plasma interaction with square solar sails on the order of the sizes being considered for a Geostorm mission (50 m x 50 m and 75 m x 75 m corresponding to approx.2 and approx.3 times the Debye length in the plasma) is carried out. First, a crude current balance for the sail surface immersed in the plasma environment and in sunlight was used to estimate the surface potential of the model sails. This gave surface potentials of approx.10 V positive relative to the solar wind plasma. A 3-D, Electrostatic Particle-in-Cell (PIC) code was then used to simulate the solar wind flowing around the solar sail. It is assumed in the code that the solar wind protons can be treated as particles while the electrons follow a Boltzmann distribution. Next, the electric field and particle trajectories are solved self-consistently to give the proton flow field, the electrostatic field around the sail, and the plasma density in 3-D. The model sail was found to be surrounded by a plasma sheath within which the potential is positive compared to the ambient plasma and followed by a separate plasma wake which is negative relative to the plasma. This structure departs dramatically from a negatively charged plate such as might be found in the Earth s ionosphere on the night side where both the plate and its negative wake are contiguous. The implications of these findings are discussed as they apply to the proposed Geostorm solar sail mission.

  2. ENERGY DISSIPATION PROCESSES IN SOLAR WIND TURBULENCE

    SciTech Connect

    Wang, Y.; Wei, F. S.; Feng, X. S.; Sun, T. R.; Zuo, P. B.; Xu, X. J.; Zhang, J.

    2015-12-15

    Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation ultimately cannot be achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy dissipation process.

  3. Complexity induced solar wind turbulence and evolution

    NASA Astrophysics Data System (ADS)

    Chang, T.

    2003-04-01

    "Complexity" has become a hot topic in nearly every field of modern physics. Solar wind plasmas are of no exception. Recently, Chang [2002], in analogy with theories developed for phenomena observed in the magnetotail and the auroral zone [Chang, 1999; 2001], demonstrated that the sporadic and localized interactions of magnetic coherent structures arising from plasma resonances could be the origin of "complexity" of nonresonant pseudo-2D spatiotemporal fluctuations in solar wind turbulence and in the coronal hole base. Such nonresonant fluctuations were shown to exist in the solar wind by Matthaeus et al. [1990] in terms of the two-dimensional correlation as a function of distance parallel and perpendicular to the mean magnetic field based on the ISEE-3 magnetometer data. Other evidences indicating the existence of such type of fluctuations in the solar wind have been reported by Tu et al. [1989], Tu and Marsch [1990, 1991], Bruno and Bavassano [1991], Bavassano and Bruno [1992], Bruno et al. [2001], and others. These results explain [Tu and Marsch, 1991] why the Alfvén ratio (a quantitative measure of Alfvénicity) is often found to be less than one in the solar wind [Belcher and Davis 1971, Solodyna et al., 1977, Bruno et al, 1985, Roberts et al., 1990], particularly for the space range farther than 0.3 AU. The above observational results are also consistent with the conclusions obtained from 2D MHD numerical simulations [Matthaeus and Larkin, 1986, Roberts and Goldstein, 1988, Goldstein et al., 1989, Roberts et al., 1991, and Roberts, 1992]. Such findings have led Chang [2002] to suggest the following evolutional scenario for the plasma turbulence in the generic fast solar wind. In and near the coronal hole base, the turbulent fluctuations are predominantly nonresonantly generated by pseudo-2D nonlinear interactions. As the fluctuations emerge from the coronal hole base, they propagate resonantly in the field-aligned direction primarily as Alfvén waves

  4. Magnetofluid Turbulence in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Goldstein, Melvyn L.

    2008-01-01

    The solar wind shows striking characteristics that suggest that it is a turbulent magnetofluid, but the picture is not altogether simple. From the earliest observations, a strong correlation between magnetic fluctuations and plasma velocity fluctuations was noted. The high corrections suggest that the fluctuations are Alfven waves. In addition, the power spectrum of the magnetic fluctuation showed evidence of an inertial range that resembled that seen in fully-developed fluid turbulence. Alfven waves, however, are exact solutions of the equations of incompressible magnetohydrodynamics. Thus, there was a puzzle: how can a magnetofluid consisting of Alfven waves be turbulent? The answer lay in the role of velocity shears in the solar wind that could drive turbulent evolution. Puzzles remain: for example, the power spectrum of the velocity fluctuations is less steep than the slope of the magnetic fluctuations, nor do we understand even now why the solar wind appears to be nearly incompressible with a -5/3 power-spectral index.

  5. Solar wind charge exchange during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Robertson, I. P.; Cravens, T. E.; Sibeck, D. G.; Collier, M. R.; Kuntz, K. D.

    2012-04-01

    On 2001 March 31 a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 R_E. The NASA/GSFC Community Coordinated Modeling Center (CCMC) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et al. then modeled the expected soft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on 2000 July 14 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  6. Genesis Capsule Yields Solar Wind Samples

    NASA Astrophysics Data System (ADS)

    Wiens, Roger C.; Burnett, Donald S.; Stansbery, Eileen K.; McNamara, Karen M.

    2004-11-01

    NASA's Genesis capsule, carrying the first samples ever returned from beyond the Moon, took a hard landing in the western Utah desert on 8 September after its parachutes failed to deploy. Despite the impact, estimated at 310 km per hour, some valuable solar wind collector materials have been recovered. With these samples, the Genesis team members are hopeful that nearly all of the primary science goals may be met. The Genesis spacecraft was launched in August 2001 to collect and return samples of solar wind for precise isotopic and elemental analysis. The spacecraft orbited the Earth-Sun Lagrangian point (L1), ~1.5 million km sunward of the Earth, for 2.3 years. It exposed ultrapure materials-including wafers of silicon, silicon carbide, germanium, chemically deposited diamond, gold, aluminum, and metallic glass-to solar wind ions, which become embedded within the substrates' top 100 nm of these materials.

  7. 3D Wind Reconstruction and Turbulence Estimation in the Boundary Layer from Doppler Lidar Measurements using Particle Method

    NASA Astrophysics Data System (ADS)

    Rottner, L.; Baehr, C.

    2014-12-01

    Turbulent phenomena in the atmospheric boundary layer (ABL) are characterized by small spatial and temporal scales which make them difficult to observe and to model.New remote sensing instruments, like Doppler Lidar, give access to fine and high-frequency observations of wind in the ABL. This study suggests to use a method of nonlinear estimation based on these observations to reconstruct 3D wind in a hemispheric volume, and to estimate atmospheric turbulent parameters. The wind observations are associated to particle systems which are driven by a local turbulence model. The particles have both fluid and stochastic properties. Therefore, spatial averages and covariances may be deduced from the particles. Among the innovative aspects, we point out the absence of the common hypothesis of stationary-ergodic turbulence and the non-use of particle model closure hypothesis. Every time observations are available, 3D wind is reconstructed and turbulent parameters such as turbulent kinectic energy, dissipation rate, and Turbulent Intensity (TI) are provided. This study presents some results obtained using real wind measurements provided by a five lines of sight Lidar. Compared with classical methods (e.g. eddy covariance) our technic renders equivalent long time results. Moreover it provides finer and real time turbulence estimations. To assess this new method, we suggest computing independently TI using different observation types. First anemometer data are used to have TI reference.Then raw and filtered Lidar observations have also been compared. The TI obtained from raw data is significantly higher than the reference one, whereas the TI estimated with the new algorithm has the same order.In this study we have presented a new class of algorithm to reconstruct local random media. It offers a new way to understand turbulence in the ABL, in both stable or convective conditions. Later, it could be used to refine turbulence parametrization in meteorological meso-scale models.

  8. Configuration and Evaluation of a Dual-Doppler 3-D Wind Field System

    NASA Technical Reports Server (NTRS)

    Crawford, Winifred C.

    2014-01-01

    Current LSP, GSDO, and SLS space vehicle operations are halted when wind speeds from specific directions exceed defined thresholds and when lightning is a threat. Strong winds and lightning are difficult parameters for the 45th Weather Squadron (45 WS) to forecast, yet are important in the protection of customer vehicle operations and the personnel that conduct them. A display of the low-level horizontal wind field to reveal areas of high winds or convergence would be a valuable tool for forecasters in assessing the timing of high winds, or convection initiation and subsequent lightning occurrence. This is especially important for areas where no weather observation platforms exist. Developing a dual-Doppler radar capability would provide such a display to assist forecasters in predicting high winds and convection initiation. The wind fields can also be used to initialize a local mesoscale numerical weather prediction model to help improve the model forecast winds, convection initiation, and other phenomena. The 45 WS and NWS MLB tasked the Applied Meteorology Unit (AMU) to develop a dual- Doppler wind field display using data from the 45th Space Wing radar, known as the Weather Surveillance Radar (WSR), NWS MLB Weather Surveillance Radar 1988 Doppler (KMLB), and the Orlando International Airport Terminal Doppler Weather Radar (KMCO). They also stipulated that the software used should be freely available. The AMU evaluated two software packages and, with concurrence from NWS MLB and the 45 WS, chose the Warning Decision Support System-Integrated Information (WDSS-II). The AMU collected data from two significant weather cases: a tornadic event on 14 April 2013 and a severe wind and hail event on 12 February 2014. For the 14 April case, the data were from WSR and KMLB. For the 12 February case, the data were from KMCO and KMLB. The AMU installed WDSS-II on a Linux PC, then processed and quality controlled the radar data for display and analysis using WDSS-II tools

  9. Solar wind turbulence: Observations of MHD effects

    NASA Technical Reports Server (NTRS)

    Bavassano, B.

    1995-01-01

    Since the first in-situ observations it was realized that the solar wind is permeated by large-amplitude variations on a very extended range of scales. In this paper an overview of our present state of knowledge for fluctuations in the magnetohydrodynamic (MHD) regime is given. These fluctuations are an important component of the solar wind variability and notably contribute to the overall energy and momentum flux. They generally have a turbulent character and their amplitude is large enough to suggest the presence of nonlinear effects. In recent years the use of high time-resolution data on an extended range of heliocentric distances has allowed major steps towards a satisfactory understanding of the solar wind MHD fluctuations. Their radial evolution in the expanding wind has been determined through detailed analyses of the variations in their spectral features. correlations. and anisotropics. The role of interplanetary sources has been carefully investigated. The influence of interactions with structures convected by the solar wind has been examined. Fluctuations have been studied in the light of theories developed to draw together the effects of both incompressibility and compressibility. Increasing attention has been devoted to the intermittent character of the turbulence. Finally, very recent observations by Ulysses at high heliographic latitudes have allowed the first in-situ analysis of turbulence features in polar regions of the heliosphere.

  10. Solar Wind Change Exchange from the Magnetosheath

    NASA Technical Reports Server (NTRS)

    Snowden, Steve

    2008-01-01

    We report the results of a long (approximately 100 ks) XMM-Newton observation designed to observe solar wind charge exchange emission (SWCX) from Earth's magnetosheath. By luck, the observation took place during a period of minimal solar wind flux so the SWCX emission was also minimal. Never-the-less, there is a significant if not stunning correlation between the observed O VIII count rate and our model for magnetosheath emission. We also report on the observed O VII and O VII emission.

  11. Standing shocks in the inner solar wind

    NASA Technical Reports Server (NTRS)

    Leer, Egil; Holzer, Thomas E.

    1990-01-01

    It has been pointed out by several authors that the equations describing rapidly diverging flow in the solar wind and in related astrophysical systems allow for solutions with standing shocks in the acceleration region of the flow. The range of plasma and flow-geometry parameters that allow for such solutions are investigated. It is shown that, for reasonable geometries, shocks can occur only for a very narrow range of flow parameters in the case of the solar wind. Similar results can be expected for related astrophysical systems.

  12. Eta Carinae: An Observational Testbed for 3-D Interacting Wind Modeling

    NASA Technical Reports Server (NTRS)

    Gull, Theodore; Madura, Tom; Groh, Jose; Corcoran, Mike; Owocki, Stan

    2011-01-01

    Eta Car, with its very massive interacting winds, provides shocked arc-like structures dense enough to trace in forbidden emission lines out to 0.7" (1700 AU). As the massive binary is in a very elliptical orbit (e approx. 0.9), the spatial and velocity structures of these winds change over the 5.54 year period. We can tract ionization structures by several forbidden emission lines. With the addition of radiative transfer on a time-step frame-by-frame basis, we are learning much new information on the ballistic structures, and may gain insight on how molecules and dust might form in these very massive systems.

  13. Capabilities of wind tunnels with two-adaptive walls to minimize boundary interference in 3-D model testing

    NASA Technical Reports Server (NTRS)

    Rebstock, Rainer; Lee, Edwin E., Jr.

    1989-01-01

    An initial wind tunnel test was made to validate a new wall adaptation method for 3-D models in test sections with two adaptive walls. First part of the adaptation strategy is an on-line assessment of wall interference at the model position. The wall induced blockage was very small at all test conditions. Lift interference occurred at higher angles of attack with the walls set aerodynamically straight. The adaptation of the top and bottom tunnel walls is aimed at achieving a correctable flow condition. The blockage was virtually zero throughout the wing planform after the wall adjustment. The lift curve measured with the walls adapted agreed very well with interference free data for Mach 0.7, regardless of the vertical position of the wing in the test section. The 2-D wall adaptation can significantly improve the correctability of 3-D model data. Nevertheless, residual spanwise variations of wall interference are inevitable.

  14. Solar wind composition from the Moon;

    NASA Astrophysics Data System (ADS)

    Bochsler, P.

    1994-06-01

    The lunar regolith contains the best accessible record of the solar wind composition of the past few billion years. Interpreting this record crucially depends on our understanding of the implantation mechanisms, potential alternative sources other than the solar wind, storage and degradation processes, and transport- and loss-mechanisms of trapped particles in the regolith. We therefore suggest that a future mission to the Moon should contain the following objectives: (1) A thorough in-situ investigation of the contemporary solar wind composition by means of long-duration exposure experiments with various techniques as baseline for investigation of the historic and ancient solar wind. (2) A multidisciplinary program, involving an experimental investigation of implantation-, storage- and loss-processes of solar particles at the conditions of the lunar environment. This program is complementary to an elaborated systematic sampling of all layers of the lunar regolith, based on the experience from the Apollo- and the Luna-missions. Difficulties with the interpretation of the lunar record are illuminated in the case of surface correlated nitrogen. (3) A complementary goal for the extensive sampling of the lunar surface is the documentation of the lunar regolith for future generations, prior to extended human activites which could have detrimental effects to the lunar environment.

  15. Adiabatic cooling of solar wind electrons

    NASA Technical Reports Server (NTRS)

    Sandbaek, Ornulf; Leer, Egil

    1992-01-01

    In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.

  16. Electrons In The Low Density Solar Wind

    NASA Technical Reports Server (NTRS)

    Ogilvie, Keith W.; Desch, Michael; Fitzenreiter, Richard; Vondrak, Richard R. (Technical Monitor)

    2000-01-01

    The recent occurrence of an interval (May 9th to May 12th, 1999) of abnormally low density solar wind has drawn attention to such events. The SWE instrument on the Wind spacecraft observed nine similar events between launch (November 1994) and August 1999: one in 1997, three in 1998, and five in January-August 1999. No such events were observed in 1996, the year of solar minimum. This already suggests a strong dependence upon solar activity. In this paper we discuss observations of the electron strahl, a strong anisotropy in the solar wind electrons above 60 eV directed along the magnetic field and observed continuously during the periods of low density in 1998 and 1999. When the solar wind density was less than 2/cc, the angular width of the strahl was below 3.5 degrees and the temperature deduced from the slope of the electron strahl phase density (as a function of energy in the energy range 200 to 800 eV) was 100 to 150 eV, equivalent to a typical coronal electron temperature. Three examples of this phenomenon, observed on Feb. 20- 22, April 26-27 and May 9-12, 1999, are discussed to show their similarity to one another. These electron observations are interpreted to show that the strahl occurs as a result of the conservation of the first adiabatic invariant, combined with the lack of coulomb collisions as suggested by Fairfield and Scudder, 1985.

  17. Workshop on Solar Activity, Solar Wind, Terrestrial Effects, and Solar Acceleration

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A summary of the proceedings from the workshop are presented. The areas covered were solar activity, solar wind, terrestrial effects, and solar acceleration. Specific topics addressed include: (1) solar cycle manifestations, both large and small scale, as well as long-term and short-term changes, including transients such as flares; (2) sources of solar wind, as identified by interplanetary observations including coronal mass ejections (CME's) or x-ray bright points, and the theory for and evolution of large-scale and small-scale structures; (3) magnetosphere responses, as observed by spacecraft, to variable solar wind and transient energetic particle emissions; and (4) origin and propagation of solar cosmic rays as related to solar activity and terrestrial effects, and solar wind coronal-hole relationships and dynamics.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  19. Simulations of the Solar Wind Interaction with the Atmosphere/Ionosphere of Venus

    NASA Astrophysics Data System (ADS)

    Ledvina, Stephen; Brecht, Stephen H.; Bougher, Stephen W.

    2016-10-01

    The latest results of high resolution 3-D hybrid particle code simulations of the solar wind interacting with the atmosphere/ionosphere of Venus will be presented. The research is focused on understanding the how the solar wind interaction with Venus results in the subsequent ionospheric losses. In addition, the simulations focus on structures caused by the interaction particularly on the pole of the planet where the convection electric field points. A variety of simulation results will be presented each with varying solar wind parameters. The hybrid particle code HALFSHEL contains a variety of physical and chemical models which will also be discussed. These include a chemistry package that produces the ionosphere on grid resolution of 10 km altitude, atmospheric densities and dynamics from the VTGCM code and the Hall and Pedersen conductivities associated with plasma neutral collisions. The specific simulations to be presented trace solar wind protons, and ionospheric O+ and O2+.

  20. Solar wind composition measurements by the Ulysses SWICS experiment during transient solar wind flows

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Gloeckler, G.; Ipavich, F. M.; Shafer, C. M.; Geiss, J.; Ogilvie, K.

    1993-01-01

    For the March/April 1991 time period, the alpha/proton abundance ratio, the proton kinetic temperature and speed distributions, and the relative abundance of O(+7) to O(+6) is determined over each 13-minute duty cycle of the Solar Wind Ion Composition Spectrometer (SWICs) experiment on Ulysses. The ratio O(+7)/O(+6) (as a relative measure of ionization temperature) is shown to be useful in identifying possible coronal mass ejection (CME) events. We report measurements of silicon/oxygen abundance ratios and silicon and oxygen charge state distributions in the solar wind during a CME event and compare these compositions to a 'normal' solar wind time period.

  1. Compact, High Energy 2-micron Coherent Doppler Wind Lidar Development for NASA's Future 3-D Winds Measurement from Space

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Koch, Grady; Yu, Jirong; Petros, Mulugeta; Beyon, Jeffrey; Kavaya, Michael J.; Trieu, Bo; Chen, Songsheng; Bai, Yingxin; Petzar, paul; Modlin, Edward A.; Barnes, Bruce W.; Demoz, Belay B.

    2010-01-01

    This paper presents an overview of 2-micron laser transmitter development at NASA Langley Research Center for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to study laser technology currently envisioned by NASA for future global coherent Doppler lidar winds measurement. The 250 mJ, 10 Hz laser was designed as an integral part of a compact lidar transceiver developed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 aircraft in autonomous operation. Recently, LaRC 2-micron coherent Doppler wind lidar system was selected to contribute to the NASA Science Mission Directorate (SMD) Earth Science Division (ESD) hurricane field experiment in 2010 titled Genesis and Rapid Intensification Processes (GRIP). The Doppler lidar system will measure vertical profiles of horizontal vector winds from the DC-8 aircraft using NASA Langley s existing 2-micron, pulsed, coherent detection, Doppler wind lidar system that is ready for DC-8 integration. The measurements will typically extend from the DC-8 to the earth s surface. They will be highly accurate in both wind magnitude and direction. Displays of the data will be provided in real time on the DC-8. The pulsed Doppler wind lidar of NASA Langley Research Center is much more powerful than past Doppler lidars. The operating range, accuracy, range resolution, and time resolution will be unprecedented. We expect the data to play a key role, combined with the other sensors, in improving understanding and predictive algorithms for hurricane strength and track. 1

  2. 3D turbulence measurements in inhomogeneous boundary layers with three wind LiDARs

    NASA Astrophysics Data System (ADS)

    Carbajo Fuertes, Fernando; Valerio Iungo, Giacomo; Porté-Agel, Fernando

    2014-05-01

    One of the most challenging tasks in atmospheric anemometry is obtaining reliable turbulence measurements of inhomogeneous boundary layers at heights or in locations where is not possible or convenient to install tower-based measurement systems, e.g. mountainous terrain, cities, wind farms, etc. Wind LiDARs are being extensively used for the measurement of averaged vertical wind profiles, but they can only successfully accomplish this task under the limiting conditions of flat terrain and horizontally homogeneous flow. Moreover, it has been shown that common scanning strategies introduce large systematic errors in turbulence measurements, regardless of the characteristics of the flow addressed. From the point of view of research, there exist a variety of techniques and scanning strategies to estimate different turbulence quantities but most of them rely in the combination of raw measurements with atmospheric models. Most of those models are only valid under the assumption of horizontal homogeneity. The limitations stated above can be overcome by a new triple LiDAR technique which uses simultaneous measurements from three intersecting Doppler wind LiDARs. It allows for the reconstruction of the three-dimensional velocity vector in time as well as local velocity gradients without the need of any turbulence model and with minimal assumptions [EGU2013-9670]. The triple LiDAR technique has been applied to the study of the flow over the campus of EPFL in Lausanne (Switzerland). The results show the potential of the technique for the measurement of turbulence in highly complex boundary layer flows. The technique is particularly useful for micrometeorology and wind engineering studies.

  3. Wind/solar resource in Texas

    SciTech Connect

    Nelson, V.; Starcher, K.; Gaines, H.

    1997-12-31

    Data are being collected at 17 sites to delineate a baseline for the wind and solar resource across Texas. Wind data are being collected at 10, 25, and 40 m (in some cases at 50 m) to determine wind shear and power at hub heights of large turbines. Many of the sites are located in areas of predicted terrain enhancement. The typical day in a month for power and wind turbine output was calculated for selected sites and combination of sites; distributed systems. Major result to date is that there is the possibility of load matching in South Texas during the summer months, even though the average values by month indicate a low wind potential.

  4. Implications of solar wind measurements for solar models and composition

    NASA Astrophysics Data System (ADS)

    Serenelli, Aldo; Scott, Pat; Villante, Francesco L.; Vincent, Aaron C.; Asplund, Martin; Basu, Sarbani; Grevesse, Nicolas; Peña-Garay, Carlos

    2016-11-01

    We critically examine recent claims of a high solar metallicity by von Steiger & Zurbuchen (2016, vSZ16) based on in situ measurements of the solar wind, rather than the standard spectroscopically inferred abundances (Asplund et al. 2009, hereafter AGSS09). We test the claim by Vagnozzi et al. (2016) that a composition based on the solar wind enables one to construct a standard solar model in agreement with helioseismological observations and thus solve the decades-old solar modelling problem. We show that, although some helioseismological observables are improved compared to models computed with spectroscopic abundances, most are in fact worse. The high abundance of refractory elements leads to an overproduction of neutrinos, with a predicted 8B flux that is nearly twice its observed value, and 7Be and CNO fluxes that are experimentally ruled out at high confidence. A combined likelihood analysis shows that models using the vSZ16 abundances are worse than AGSS09 despite a higher metallicity. We also present astrophysical and spectroscopic arguments showing the vSZ16 composition to be an implausible representation of the solar interior, identifying the first ionization potential effect in the outer solar atmosphere and wind as the likely culprit.

  5. The 3-D description of vertical current sheets with application to solar flares

    NASA Technical Reports Server (NTRS)

    Fontenla, Juan M.; Davis, J. M.

    1991-01-01

    Following a brief review of the processes which have been suggested for explaining the occurrence of solar flares we suggest a new scenario which builds on the achievements of the previous suggestion that the current sheets, which develop naturally in 3-D cases with gravity from impacting independent magnetic structures (i.e., approaching current systems), do not consist of horizontal currents but are instead predominantly vertical current systems. This suggestion is based on the fact that as the subphotospheric sources of the magnetic field displace the upper photosphere and lower chromosphere regions, where plasma beta is near unity, will experience predominantly horizontal mass motions which will lead to a distorted 3-D configurations of the magnetic field having stored free energy. In our scenario, a vertically flowing current sheet separates the plasma regions associated with either of the subphotospheric sources. This reflects the balanced tension of the two stressed fields which twist around each other. This leads naturally to a metastable or unstable situation as the twisted field emerges into a low beta region where vertical motions are not inhibited by gravity. In our flare scenario the impulsive energy release occurs, initially, not by reconnection but mainly by the rapid change of the magnetic field which has become unstable. During the impulsive phase the field lines contort in such way as to realign the electric current sheet into a minimum energy horizontal flow. This contortion produces very large electric fields which will accelerate particles. As the current evolves to a horizontal configuration the magnetic field expands vertically, which can be accompanied by eruptions of material. The instability of a horizontal current is well known and causes the magnetic field to undergo a rapid outward expansion. In our scenario, fast reconnection is not necessary to trigger the flare, however, slow reconnection would occur continuously in the current layer

  6. Validation of US3D for Capsule Aerodynamics using 05-CA Wind Tunnel Test Data

    NASA Technical Reports Server (NTRS)

    Schwing, Alan

    2012-01-01

    RANS is ill-suited for analysis of these problems. For transonic and supersonic cases, US3D shows fairly good agreement using DES across all cases. Separation prediction and resulting backshell pressure are problems across all portions of this analysis. This becomes more of an issue at lower Mach numbers: .Stagnation pressures not as large - wake and backshell are more significant .Errors on shoulder act on a large area - small discrepancies manifest as large changes Subsonic comparisons are mixed with regard to integrated loads and merit more attention. Dominant unsteady behavior (wake shedding) resolved well, though.

  7. Coronal Plumes in the Fast Solar Wind

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  8. Substorm occurrence during quiet solar wind driving

    NASA Astrophysics Data System (ADS)

    Pulkkinen, T. I.; Partamies, N.; Kilpua, E. K. J.

    2014-04-01

    We examine the OMNI database and International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer chain records to study the substorm occurrence and characteristics during quiet solar driving periods, especially during the solar minimum period in 2009. We define substorm-like activations as periods where the hourly average AL is below -200 nT. Using the OMNI data set, we demonstrate that there are limiting solar wind speed, interplanetary magnetic field magnitude, and driving electric field values below which substorm-like activations (AL < 200 nT, intensification and decay of the electrojet) do not occur. These minimum parameter values are V < 266 km/s, B < 1.4 nT, and E < 0.025 mV/m such low values are observed less than 1% of the time. We also show that for the same level of driving solar wind electric field, the electrojet intensity is smaller (by few tens of nT), and the electrojet resides farther poleward (by over 1°) during extended quiet solar driving in 2009 than during average solar activity conditions. During the solar minimum period in 2009, we demonstrate that substorm-like activations can be identified from the IMAGE magnetometer chain observations during periods when the hourly average IL index is below -100 nT. When the hourly IL activity is smaller than that, which covers 87% of the nighttime observations, the electrojet does not show coherent behavior. We thus conclude that substorm recurrence time during very quiet solar wind driving conditions is about 5-8 h, which is almost double that of the average solar activity conditions.

  9. RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

    SciTech Connect

    Airapetian, Vladimir S.; Usmanov, Arcadi V. E-mail: avusmanov@gmail.com

    2016-02-01

    Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion.

  10. Production of 3D wind field near the surface using WRF and MUKLIMO

    NASA Astrophysics Data System (ADS)

    Sukjun, L.

    2015-12-01

    The extreme weather conditions become frequent and severe with global warming. To prevent and cope forest disaster like a forest fire, we need an accurate micrometeorological prediction system for mountainous regions. This study addressed the forest fires occurred at Bonghwa and Gangneung in March, 2013. We constructed and optimized the prediction system that were required to interpret and simulate the forest micrometeorology. At first, we examined WRF physical sensitivity. Subsequently, KMA AWS observation data were assimilated using three-dimensional variation data assimilation method. The effectiveness of the assimilation was examined by using AWS observations enhanced with the Forest Research Institute observations. Finally, The 100 meters spatial resolution wind data were obtained by using the MUKLIMO for the given wind vector from WRF.

  11. Apollo 11 solar wind composition experiment: first results.

    PubMed

    Bühler, F; Eberhardt, P; Geiss, J; Meister, J; Signer, P

    1969-12-19

    The helium-4 solar wind flux during the Apollo 11 lunar surface excursion was (6.3 +/- 1.2) x 10(6) atoms per square centimeter per second. The solar wind direction and energy are essentially not perturbed by the moon. Evidence for a lunar solar wind albedo was found.

  12. Identifying Wind and Solar Ramping Events: Preprint

    SciTech Connect

    Florita, A.; Hodge, B. M.; Orwig, K.

    2013-01-01

    Wind and solar power are playing an increasing role in the electrical grid, but their inherent power variability can augment uncertainties in power system operations. One solution to help mitigate the impacts and provide more flexibility is enhanced wind and solar power forecasting; however, its relative utility is also uncertain. Within the variability of solar and wind power, repercussions from large ramping events are of primary concern. At the same time, there is no clear definition of what constitutes a ramping event, with various criteria used in different operational areas. Here the Swinging Door Algorithm, originally used for data compression in trend logging, is applied to identify variable generation ramping events from historic operational data. The identification of ramps in a simple and automated fashion is a critical task that feeds into a larger work of 1) defining novel metrics for wind and solar power forecasting that attempt to capture the true impact of forecast errors on system operations and economics, and 2) informing various power system models in a data-driven manner for superior exploratory simulation research. Both allow inference on sensitivities and meaningful correlations, as well as the ability to quantify the value of probabilistic approaches for future use in practice.

  13. Solar Wind Drivers for Steady Magnetospheric Convection

    NASA Technical Reports Server (NTRS)

    McPherron, Robert L.; O'Brien, T. Paul; Thompson, Scott; Lui, A. T. Y. (Editor)

    2005-01-01

    Steady magnetospheric convection (SMC) also known as convection bays, is a particular mode of response of the magnetosphere to solar wind coupling. It is characterized by convection lasting for times longer than a typical substorm recovery during which no substorms expansions can be identified. It is generally believed that the solar wind must be unusually steady for the magnetosphere to enter this state. However, most previous studies have assumed this is true and have used such conditions to identify events. In a preliminary investigation using only the AE and AL indices to select events we have shown that these expectations are generally correct. SMC events seem to be associated with slow speed solar wind and moderate, stable IMF Bz. In this report we extend our previous study including additional parameters and the time variations in various statistical quantities. For the intervals identified as SMCs we perform a detailed statistical analysis of the properties of different solar wind variables. We compare these statistics to those determined from all data, and from intervals in which substorms but not SMCs are present. We also consider the question of whether substorms are required to initiate and terminate an SMC. We conclude that the intervals we have identified as SMC are likely to be examples of the original Dungey concept of balanced reconnection at a pair of x-lines on the day and night side of the Earth.

  14. Hemispheric differences in solar wind - magnetosphere interactions

    NASA Astrophysics Data System (ADS)

    Reistad, J. P.; Ostgaard, N.; Laundal, K.; Snekvik, K.; Tenfjord, P.; Oksavik, K.

    2014-12-01

    Although the aurora to a large degree behave similar in the two hemispheres, recent simultaneous observations of the global aurora from space have revealed that sometimes rather large intensity and location asymmetries are present in the global aurora. From event studies using e.g. conjugate imaging, multiple mechanisms have been proposed to be responsible for the asymmetric aurora. However, we know very little about their general importance. We have investigated the general importance of an asymmetric solar wind dynamo. It has been suggested that the radial component of the IMF can modify the energy conversion between the solar wind and magnetosphere differently in the two hemispheres in a general sense. By looking at the global aurora using IMAGE WIC during carefully selected events minimally contaminated by other mechanisms affecting the two hemispheres differently, we find that the dusk side aurora depend oppositely on the radial IMF direction in the two hemispheres. These results are consistent with an asymmetric solar wind dynamo where the hemispheric preference is controlled by the radial IMF. This is the first study indicating the importance of the asymmetric solar wind dynamo in a general sense. A different mechanism, the asymmetric loading of magnetic flux during IMF By conditions is also expected to account for North-South asymmetries in the nightside global aurora. This will be investigated using a similar approach to establish the general importance of of this IMF By mechanism on the global aurora in the two hemispheres.

  15. Energy Primer: Solar, Water, Wind, and Biofuels.

    ERIC Educational Resources Information Center

    Portola Inst., Inc., Menlo Park, CA.

    This is a comprehensive, fairly technical book about renewable forms of energy--solar, water, wind, and biofuels. The biofuels section covers biomass energy, agriculture, aquaculture, alcohol, methane, and wood. The focus is on small-scale systems which can be applied to the needs of the individual, small group, or community. More than one-fourth…

  16. Combined Solar and Wind Energy Systems

    NASA Astrophysics Data System (ADS)

    Tripanagnostopoulos, Y.; Souliotis, M.; Makris, Th.

    2010-01-01

    In this paper we present the new concept of combined solar and wind energy systems for buildings applications. Photovoltaics (PV) and small wind turbines (WTs) can be install on buildings, in case of sufficient wind potential, providing the building with electricity. PVs can be combined with thermal collectors to form the hybrid photovoltaic/thermal (PV/T) systems. The PVs (or the PV/Ts) and WT subsystems can supplement each other to cover building electrical load. In case of using PV/T collectors, the surplus of electricity, if not used or stored in batteries, can increase the temperature of the thermal storage tank of the solar thermal unit. The description of the experimental set-up of the suggested PV/T/WT system and experimental results are presented. In PV/T/WT systems the output from the solar part depends on the sunshine time and the output of the wind turbine part depends on the wind speed and is obtained any time of day or night. The use of the three subsystems can cover a great part of building energy load, contributing to conventional energy saving and environment protection. The PV/T/WT systems are considered suitable in rural and remote areas with electricity supply from stand-alone units or mini-grid connection. PV/T/WT systems can also be used in typical grid connected applications.

  17. Solar cycle changes in the polar solar wind

    NASA Technical Reports Server (NTRS)

    Coles, W. A.; Rickett, B. J.; Rumsey, V. H.; Kaufman, J. J.; Turley, D. G.; Ananthakrishnan, S.; Armstrong, J. W.; Harmons, J. K.; Scott, S. L.; Sime, D. G.

    1980-01-01

    It is noted that although the 11 year solar cycle was first recognized in 1843, it is still only poorly understood. Further, while there are satisfactory models for the magnetic variations, the underlying physics is still obscure. New observations on the changing three-dimensional form of the solar wind are presented which help relate some of the modulations observed in geomagnetic activity, the ionosphere, and the flux of galactic cosmic rays.

  18. Material Interactions with Solar Wind Ion Environments

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; McWilliams, Brett

    2006-01-01

    Solar wind composition is dominated by hydrogen (approx.96%) and helium (approx.3 to 4%) with a minor fraction (less than or equal to 1%) of heavy ions. Hydrogen (helium) ions impact spacecraft surfaces with energies from 0.5 to 5 keV (1.8 to 21 keV) due to variations in solar wind velocity from 300 km/s to 1000 km/sec with extremes of a few 10 s keV during periods of extremely high solar wind velocity exceeding 1000 km/sec. Mean impact energies are typically on the order of approximately 1 keV and 4 keV for hydrogen ions and helium ions, respectively. These energies are typically of the peak of the energy dependent light ion sputter yields for hydrogen and helium on many metals. In addition, light ions with kilovolt energies have been shown to produce blister (or exfoliation) damage to metal surfaces due to formation of high pressure gas bubbles within the materials when exposed to ion fluences on the order of 10(exp 16 to (10(exp 17 ions/sq cm. A number of spacecraft designs for current and future missions include gossamer polymer structures with thin metallic reflection coatings to shield instruments from the Sun or solar sail propulsion systems for use in a variety of locations in the inner solar system from 0.5 to 1 AU. In addition, there is interest in designing spacecraft for solar physics missions requiring operations as close to the Sun as 0.16 to 0.2 AU. Integrity of the metallic coatings is critical in many of these applications since degradation will result in modification of material thermal properties or exposure of polymers to solar UV photons which can compromise mission requirements. This paper will evaluate the relative contributions of sputtering and blister formation to material degradation in solar wind environments over a range of radial distances from the Sun to demonstrate where solar wind environments become important for materials selection. We will first review the physics and results from laboratory measurements of light ion sputtering

  19. FUN3D Airload Predictions for the Full-Scale UH-60A Airloads Rotor in a Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Lee-Rausch, Elizabeth M.; Biedron, Robert T.

    2013-01-01

    An unsteady Reynolds-Averaged Navier-Stokes solver for unstructured grids, FUN3D, is used to compute the rotor performance and airloads of the UH-60A Airloads Rotor in the National Full-Scale Aerodynamic Complex (NFAC) 40- by 80-foot Wind Tunnel. The flow solver is loosely coupled to a rotorcraft comprehensive code, CAMRAD-II, to account for trim and aeroelastic deflections. Computations are made for the 1-g level flight speed-sweep test conditions with the airloads rotor installed on the NFAC Large Rotor Test Apparatus (LRTA) and in the 40- by 80-ft wind tunnel to determine the influence of the test stand and wind-tunnel walls on the rotor performance and airloads. Detailed comparisons are made between the results of the CFD/CSD simulations and the wind tunnel measurements. The computed trends in solidity-weighted propulsive force and power coefficient match the experimental trends over the range of advance ratios and are comparable to previously published results. Rotor performance and sectional airloads show little sensitivity to the modeling of the wind-tunnel walls, which indicates that the rotor shaft-angle correction adequately compensates for the wall influence up to an advance ratio of 0.37. Sensitivity of the rotor performance and sectional airloads to the modeling of the rotor with the LRTA body/hub increases with advance ratio. The inclusion of the LRTA in the simulation slightly improves the comparison of rotor propulsive force between the computation and wind tunnel data but does not resolve the difference in the rotor power predictions at mu = 0.37. Despite a more precise knowledge of the rotor trim loads and flight condition, the level of comparison between the computed and measured sectional airloads/pressures at an advance ratio of 0.37 is comparable to the results previously published for the high-speed flight test condition.

  20. The origin of the solar wind

    NASA Technical Reports Server (NTRS)

    Axford, W. I.; McKenzie, J. F.

    1995-01-01

    The high speed solar wind, which is associated with coronal holes and unipolar interplanetary magnetic field, has now been observed in situ beyond 0.3 a.u. and at latitudes up to 80 degrees. Its important characteristics are that it is remarkably steady in terms of flow properties and composition and that the ions, especially minor species, are favored in terms of heating and acceleration. We have proposed that the high speed wind, with its associated coronal holes, forms the basic mode of solar wind flow. In contrast, the low speed wind is inherently non-stationary, filamentary and not in equilibrium with conditions at the coronal base. It is presumably the result of continual reconfigurations of the force-free magnetic field in the low-latitude closed corona which allow trapped plasma to drain away along transiently open flux tubes. Observations of high speed solar wind close to its source are hampered by the essential heterogeneity of the corona, even at sunspot minimum. In particular it is difficult to determine more than limits to the density, temperature and wave amplitude near the coronal base as a result of contamination from fore- and back-ground plasma. We interpret the observations as indicating that the high speed solar wind originates in the chromospheric network, covering only about 1% of the surface of the sun, where the magnetic field is complex and not unipolar. As a result of small-scale reconnection events in this 'furnace', Alfven waves are generated with a flat spectrum covering the approximate range 10 kHz to 10 Hz. The plasma is likely to be produced as a result of downwards thermal conduction and possibly photoionization at the top of the low density chromospheric interface to the furnace, thus controlling the mass flux in the wind. The immediate source of free (magnetic) energy is in the form of granule-sized loops which are continually carried into the network from the sides. The resulting wave spectrum is such that energy can be

  1. Characterizing microscale aluminum composite layer properties on silicon solar cells with hybrid 3D scanning force measurements.

    PubMed

    Bae, Sung-Kuk; Choi, Beomjoon; Chung, Haseung; Shin, Seungwon; Song, Hee-eun; Seo, Jung Hwan

    2016-03-07

    This article presents a novel technique to estimate the mechanical properties of the aluminum composite layer on silicon solar cells by using a hybrid 3-dimensional laser scanning force measurement (3-D LSFM) system. The 3-D LSFM system measures the material properties of sub-layers constituting a solar cell. This measurement is critical for realizing high-efficient ultra-thin solar cells. The screen-printed aluminum layer, which significantly affects the bowing phenomenon, is separated from the complete solar cell by removing the silicon (Si) layer with deep reactive ion etching. An elastic modulus of ~15.1 GPa and a yield strength of ~35.0 MPa for the aluminum (Al) composite layer were obtained by the 3-D LSFM system. In experiments performed for 6-inch Si solar cells, the bowing distances decreased from 12.02 to 1.18 mm while the Si layer thicknesses increased from 90 to 190 μm. These results are in excellent agreement with the theoretical predictions for ultra-thin Si thickness (90 μm) based on the obtained Al composite layer properties.

  2. Characterizing microscale aluminum composite layer properties on silicon solar cells with hybrid 3D scanning force measurements

    NASA Astrophysics Data System (ADS)

    Bae, Sung-Kuk; Choi, Beomjoon; Chung, Haseung; Shin, Seungwon; Song, Hee-Eun; Seo, Jung Hwan

    2016-03-01

    This article presents a novel technique to estimate the mechanical properties of the aluminum composite layer on silicon solar cells by using a hybrid 3-dimensional laser scanning force measurement (3-D LSFM) system. The 3-D LSFM system measures the material properties of sub-layers constituting a solar cell. This measurement is critical for realizing high-efficient ultra-thin solar cells. The screen-printed aluminum layer, which significantly affects the bowing phenomenon, is separated from the complete solar cell by removing the silicon (Si) layer with deep reactive ion etching. An elastic modulus of ~15.1 GPa and a yield strength of ~35.0 MPa for the aluminum (Al) composite layer were obtained by the 3-D LSFM system. In experiments performed for 6-inch Si solar cells, the bowing distances decreased from 12.02 to 1.18 mm while the Si layer thicknesses increased from 90 to 190 μm. These results are in excellent agreement with the theoretical predictions for ultra-thin Si thickness (90 μm) based on the obtained Al composite layer properties.

  3. Characterizing microscale aluminum composite layer properties on silicon solar cells with hybrid 3D scanning force measurements

    PubMed Central

    Bae, Sung-Kuk; Choi, Beomjoon; Chung, Haseung; Shin, Seungwon; Song, Hee-eun; Seo, Jung Hwan

    2016-01-01

    This article presents a novel technique to estimate the mechanical properties of the aluminum composite layer on silicon solar cells by using a hybrid 3-dimensional laser scanning force measurement (3-D LSFM) system. The 3-D LSFM system measures the material properties of sub-layers constituting a solar cell. This measurement is critical for realizing high-efficient ultra-thin solar cells. The screen-printed aluminum layer, which significantly affects the bowing phenomenon, is separated from the complete solar cell by removing the silicon (Si) layer with deep reactive ion etching. An elastic modulus of ~15.1 GPa and a yield strength of ~35.0 MPa for the aluminum (Al) composite layer were obtained by the 3-D LSFM system. In experiments performed for 6-inch Si solar cells, the bowing distances decreased from 12.02 to 1.18 mm while the Si layer thicknesses increased from 90 to 190 μm. These results are in excellent agreement with the theoretical predictions for ultra-thin Si thickness (90 μm) based on the obtained Al composite layer properties. PMID:26948248

  4. The Origin of the Solar Wind

    NASA Astrophysics Data System (ADS)

    Woo, Richard; Habbal, Shadia Rifai

    2002-12-01

    Nearly 1,400 years ago, Chinese astronomers noticed that comet tails always point away from the Sun. They concluded that the Sun must have chi—a basic life force—that blows the tails away. It wasn't until the middle of the 20th century that scientists understood that this "force" actually consisted of little pieces of the sun itself—protons and electrons—blowing out into the solar system as a "wind" at more than a million kilometers per hour. The traditional view of the solar wind's origins suggests that it originates from special regions on the Sun, called coronal holes. Woo and Habbal present new evidence showing that the wind actually emanates from all regions on the Sun.

  5. Decoding solar wind-magnetosphere coupling

    NASA Astrophysics Data System (ADS)

    Beharrell, M. J.; Honary, F.

    2016-10-01

    We employ a new NARMAX (Nonlinear Auto-Regressive Moving Average with eXogenous inputs) code to disentangle the time-varying relationship between the solar wind and SYM-H. The NARMAX method has previously been used to formulate a Dst model, using a preselected solar wind coupling function. In this work, which uses the higher-resolution SYM-H in place of Dst, we are able to reveal the individual components of different solar wind-magnetosphere interaction processes as they contribute to the geomagnetic disturbance. This is achieved with a graphics processing unit (GPU)-based NARMAX code that is around 10 orders of magnitude faster than previous efforts from 2005, before general-purpose programming on GPUs was possible. The algorithm includes a composite cost function, to minimize overfitting, and iterative reorthogonalization, which reduces computational errors in the most critical calculations by a factor of ˜106. The results show that negative deviations in SYM-H following a southward interplanetary magnetic field (IMF) are first a measure of the increased magnetic flux in the geomagnetic tail, observed with a delay of 20-30 min from the time the solar wind hits the bow shock. Terms with longer delays are found which represent the dipolarization of the magnetotail, the injections of particles into the ring current, and their subsequent loss by flowout through the dayside magnetopause. Our results indicate that the contribution of magnetopause currents to the storm time indices increase with solar wind electric field, E = v × B. This is in agreement with previous studies that have shown that the magnetopause is closer to the Earth when the IMF is in the tangential direction.

  6. ACCRETION OF SUPERSONIC WINDS ONTO BLACK HOLES IN 3D: STABILITY OF THE SHOCK CONE

    SciTech Connect

    Gracia-Linares, M.; Guzmán, F. S.

    2015-10-10

    Using numerical simulations we present the accretion of supersonic winds onto a rotating black hole in three dimensions. We study five representative directions of the wind with respect to the axis of rotation of the black hole and focus on the evolution and stability of the high-density shock cone that is formed during the process. We explore both the regime in which the shock cone is expected to be stable in order to confirm previous results obtained with two-dimensional simulations, and the regime in which the shock cone is expected to show a flip–flop (FF) type of instability. The methods used to attempt a triggering of the instability were (i) the accumulation of numerical errors and (ii) the explicit application of a perturbation on the velocity field after the shock cone was formed. The result is negative, that is, we did not find the FF instability within the parameter space we explored, including cases that are expected to be unstable.

  7. A stochastic aerodynamic model for stationary blades in unsteady 3D wind fields

    NASA Astrophysics Data System (ADS)

    Fluck, Manuel; Crawford, Curran

    2016-09-01

    Dynamic loads play an important roll in the design of wind turbines, but establishing the life-time aerodynamic loads (e.g. extreme and fatigue loads) is a computationally expensive task. Conventional (deterministic) methods to analyze long term loads, which rely on the repeated analysis of multiple different wind samples, are usually too expensive to be included in optimization routines. We present a new stochastic approach, which solves the aerodynamic system equations (Lagrangian vortex model) in the stochastic space, and thus arrive directly at a stochastic description of the coupled loads along a turbine blade. This new approach removes the requirement of analyzing multiple different realizations. Instead, long term loads can be extracted from a single stochastic solution, a procedure that is obviously significantly faster. Despite the reduced analysis time, results obtained from the stochastic approach match deterministic result well for a simple test-case (a stationary blade). In future work, the stochastic method will be extended to rotating blades, thus opening up new avenues to include long term loads into turbine optimization.

  8. Martian ionosphere response to solar wind variability during solar minimum

    NASA Astrophysics Data System (ADS)

    Sanchez-Cano, Beatriz; Lester, Mark; Witasse, Olivier; Mays, M. Leila; Hall, Benjamin E. S.; Milan, Stephen E.; Cartacci, Marco; Blelly, Pierre-Louis; Andrews, David; Opgenoorth, Hermann; Odstrcil, Dusan

    2016-04-01

    Solar cycle variations in solar radiation create notable density changes in the Martian ionosphere. In addition to this long-term variability, there are numerous short-term and non-recurrent solar events that hit Mars which need to be considered, such as Interplanetary Coronal Mass Ejections (ICMEs), Co-Rotation Interaction Regions (CIRs), solar flares, or solar wind high speed streams. The response of the Martian plasma system to each of these events is often unusual, especially during the long period of extreme low solar activity in 2008 and 2009. This work shows the long-term solar cycle impact on the ionosphere of Mars using data from The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), and The Analyzer of Space Plasma and Energetic Atoms (ASPERA-3), and with empirical and numerical models on Mars Express. Particular attention is given to the different ionospheric responses observed during the last, extended solar minimum. Mars' ionospheric response followed a similar pattern to the response observed in the Earth's ionosphere, despite the large differences related to the inner-origin of the magnetic field of both planets. The ionospheric temperature was cooler, the topside scale height was smaller and almost constant with altitude, the secondary ionospheric layer practically disappeared and the whole atmospheric total electron content (TEC) suffered an extreme reduction of about 30-40%, not predicted before by models. Moreover, there is a larger probability for the induced magnetic field to be present in the ionosphere, than in other phases of the solar cycle. The short-term variability is also addressed with the study of an ICME followed by a fast stream that hit Mars in March 2008, where solar wind data are provided by ACE and STEREO-B and supported by simulations using the WSA-ENLIL Model. The solar wind conditions lead to the formation of a CIR centred on the interface of the fast and the slow solar wind streams. Mars' system reacted to

  9. Wind and IMP 8 Solar Wind, Magnetosheath and Shock Data

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The purpose of this project was to provide the community access to magnetosheath data near Earth. We provided 27 years of IMP 8 magnetosheath proton velocities, densities, and temperatures with our best (usually 1-min.) time resolution. IMP 8 crosses the magnetosheath twice each 125 day orbit, and we provided magnetosheath data for the roughly 27 years of data for which magnetometer data are also available (which are needed to reliably pick boundaries). We provided this 27 years of IMP 8 magnetosheath data to the NSSDC; this data is now integrated with the IMP 8 solar wind data with flags indicating whether each data point is in the solar wind, magnetosheath, or at the boundary between the two regions. The plasma speed, density, and temperature are provided for each magnetosheath point. These data are also available on the MIT web site ftp://space .mit.edu/pub/plasma/imp/www/imp.html. We provide ASCII time-ordered rows of data giving the observation time, the spacecraft position in GSE, the velocity is GSE, the density and temperature for protons. We also have analyzed and archived on our web site the Wind magnetosheath plasma parameters. These consist of ascii files of the proton and alpha densities, speeds, and thermal speeds. These data are available at ftp://space.mit.edu/pub/plasma/wind/sheath These are the two products promised in the work statement and they have been completed in full.

  10. Solar wind measurements near Mars and their implication in the Red Planet environment

    NASA Astrophysics Data System (ADS)

    Trotignon, J. G.; Grard, R.; Barabash, S.; Lundin, R.; Dubinin, E.

    1996-02-01

    The Phobos 2 spacecraft was operational around Mars for almost two months. From 29 January to 27 March 1989, the Martian bow shock was crossed at least 200 times and the upstream regions extensively probed. The solar wind density and velocity deduced from the a.c. electric-field measurements performed with the PWS plasma and wave experiment are compared with those of the ASPERA 3-D plasma composition experiment. A reasonably good agreement is found between the 12 min averages of the plasma density numbers derived from PWS and ASPERA (considering the poor precision of the instruments): they differ by at most a factor of four. The solar wind density is found to decrease when the flow speed increases, in agreement with the stream structure of the solar wind, which results from heliomagnetic latitude dependencies of solar wind parameters. The solar wind ram pressure, which is essential to study the solar wind-Mars interaction, is also estimated: the absence of a clear relationship between this dynamic pressure and the bow shock location is confirmed. The bow shock observations performed during very high solar activity do not support the hypothesis that Mars possesses a significant intrinsic magnetic field.

  11. The Genesis Mission: Solar Wind Conditions, and Implications for the FIP Fractionation of the Solar Wind.

    SciTech Connect

    Reisenfeld, D. B.; Wiens, R. C.; Barraclough, B. L.; Steinberg, J. T; Dekoning, C. A.; Zurbuchen, T. H.; Burnett, D. S.

    2005-01-01

    The NASA Genesis mission collected solar wind on ultrapure materials between November 30, 2001 and April 1, 2004. The samples were returned to Earth September 8, 2004. Despite the hard landing that resulted from a failure of the avionics to deploy the parachute, many samples were returned in a condition that will permit analyses. Sample analyses of these samples should give a far better understanding of the solar elemental and isotopic composition (Burnett et al. 2003). Further, the photospheric composition is thought to be representative of the solar nebula, so that the Genesis mission will provide a new baseline for the average solar nebula composition with which to compare present-day compositions of planets, meteorites, and asteroids. Sample analysis is currently underway. The Genesis samples must be placed in the context of the solar and solar wind conditions under which they were collected. Solar wind is fractionated from the photosphere by the forces that accelerate the ions off of the Sun. This fractionation appears to be ordered by the first ionization potential (FIP) of the elements, with the tendency for low-FIP elements to be over-abundant in the solar wind relative to the photosphere, and high-FIP elements to be under-abundant (e.g. Geiss, 1982; von Steiger et al., 2000). In addition, the extent of elemental fractionation differs across different solarwind regimes. Therefore, Genesis collected solar wind samples sorted into three regimes: 'fast wind' or 'coronal hole' (CH), 'slow wind' or 'interstream' (IS), and 'coronal mass ejection' (CME). To carry this out, plasma ion and electron spectrometers (Barraclough et al., 2003) continuously monitored the solar wind proton density, velocity, temperature, the alpha/proton ratio, and angular distribution of suprathermal electrons, and those parameters were in turn used in a rule-based algorithm that assigned the most probable solar wind regime (Neugebauer et al., 2003). At any given time, only one of three

  12. Slow Solar Wind: Observable Characteristics for Constraining Modelling

    NASA Astrophysics Data System (ADS)

    Ofman, L.; Abbo, L.; Antiochos, S. K.; Hansteen, V. H.; Harra, L.; Ko, Y. K.; Lapenta, G.; Li, B.; Riley, P.; Strachan, L.; von Steiger, R.; Wang, Y. M.

    2015-12-01

    The Slow Solar Wind (SSW) origin is an open issue in the post SOHO era and forms a major objective for planned future missions such as the Solar Orbiter and Solar Probe Plus.Results from spacecraft data, combined with theoretical modeling, have helped to investigate many aspects of the SSW. Fundamental physical properties of the coronal plasma have been derived from spectroscopic and imaging remote-sensing data and in-situ data, and these results have provided crucial insights for a deeper understanding of the origin and acceleration of the SSW.Advances models of the SSW in coronal streamers and other structures have been developed using 3D MHD and multi-fluid equations.Nevertheless, there are still debated questions such as:What are the source regions of SSW? What are their contributions to the SSW?Which is the role of the magnetic topology in corona for the origin, acceleration and energy deposition of SSW?Which are the possible acceleration and heating mechanisms for the SSW?The aim of this study is to present the insights on the SSW origin and formationarisen during the discussions at the International Space Science Institute (ISSI) by the Team entitled ''Slowsolar wind sources and acceleration mechanisms in the corona'' held in Bern (Switzerland) in March2014--2015. The attached figure will be presented to summarize the different hypotheses of the SSW formation.

  13. Solar Wind Ablation of Terrestrial Planet Atmospheres

    NASA Technical Reports Server (NTRS)

    Moore, Thomas Earle; Fok, Mei-Ching H.; Delcourt, Dominique C.

    2009-01-01

    Internal plasma sources usually arise in planetary magnetospheres as a product of stellar ablation processes. With the ignition of a new star and the onset of its ultraviolet and stellar wind emissions, much of the volatiles in the stellar system undergo a phase transition from gas to plasma. Condensation and accretion into a disk is replaced by radiation and stellar wind ablation of volatile materials from the system- Planets or smaller bodies that harbor intrinsic magnetic fields develop an apparent shield against direct stellar wind impact, but UV radiation still ionizes their gas phases, and the resulting internal plasmas serve to conduct currents to and from the central body along reconnected magnetic field linkages. Photoionization and thermalization of electrons warms the ionospheric topside, enhancing Jeans' escape of super-thermal particles, with ambipolar diffusion and acceleration. Moreover, observations and simulations of auroral processes at Earth indicate that solar wind energy dissipation is concentrated by the geomagnetic field by a factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Thus internal plasmas enable coupling with the plasma, neutral gas and by extension, the entire body. The stellar wind is locally loaded and slowed to develop the required power. The internal source plasma is accelerated and heated, inflating the magnetosphere as it seeks escape, and is ultimately blown away in the stellar wind. Bodies with little sensible atmosphere may still produce an exosphere of sputtered matter when exposed to direct solar wind impact. Bodies with a magnetosphere and internal sources of plasma interact more strongly with the stellar wind owing to the magnetic linkage between the two created by reconnection.

  14. Significant enhancement of power conversion efficiency for dye sensitized solar cell using 1D/3D network nanostructures as photoanodes

    PubMed Central

    Wang, Hao; Wang, Baoyuan; Yu, Jichao; Hu, Yunxia; Xia, Chen; Zhang, Jun; Liu, Rong

    2015-01-01

    The single–crystalline TiO2 nanorod arrays with rutile phase have attracted much attention in the dye sensitized solar cells (DSSCs) applications because of their superior chemical stability, better electron transport properties, higher refractive index and low production cost. However, it suffers from a low surface area as compared with TiO2 nanoparticle films. In order to enlarge the surface area of TiO2 nanorod arrays, the 1D nanorods/3D nanotubes sample was synthesized using a facile two-step hydrothermal process involving hydrothermal growth 1D/3D nanorods and followed by post-etching treatment. In such bi-layer structure, the oriented TiO2 nanorods layer could provide direct pathway for fast electron transportation, and the 3D nanotubes layer offers a higher surface area for dye loading, therefore, the 1D nanorods/3D nanotubes photoanode exhibited faster electron transport and higher surface area than either 1D or 3D nanostructures alone, and an highest efficiency of 7.68% was achieved for the DSSCs based on 1D nanorods/3D nanotubes photoanode with further TiCl4 treatment. PMID:25800933

  15. Solar wind correlations: Statistical and case studies

    NASA Astrophysics Data System (ADS)

    Paularena, K. I.; Richardson, J. D.; Zastenker, G. N.; Dalin, P. A.

    1999-06-01

    Recent work on solar wind plasma correlations using data from several widely-separated spacecraft (IMP 8, INTERBALL-1, WIND, and ISEE-3) has shown that, for 6-hour periods, the average plasma correlation is ~0.7. The focus of these studies has been directed toward a statistical understanding of gross solar wind correlation behavior. In all correlations examined, lower average correlations are caused by the presence of many points from the low correlation subpopulation; nevertheless, data points from the high correlation population are still present. No single organizational factor has yet been found which adequately separates low-correlation periods from high-correlation periods. Some of the spread in correlations is due to the spatial orientations and dimensions of solar wind structures, and thus to the locational alignments of the spacecraft being correlated, but this does not adequately explain all the good or poor correlations since sometimes three nearby spacecraft show poor correlations, while sometimes three widely-separated space-craft show good correlations. Thus, in order to understand the underlying physics, detailed investigation of individual cases has been undertaken. These results will be important in assigning quality measures to space weather predictions using satellite measurements taken at L1, for example.

  16. Magnetosheath influence on solar wind - magnetosphere coupling

    NASA Astrophysics Data System (ADS)

    Pulkkinen, Tuija; Kilpua, Emilia; Dimmock, Andrew; Myllys, Minna; Osmane, Adnane; Nykyri, Katariina; Lakka, Antti

    2016-07-01

    We have shown that the solar wind - magnetosphere - ionosphere coupling is different during due northward IMF from that during due southward IMF, and that the Poynting flux at the magnetopause is not a simple function of the upstream solar wind conditions upstream of the bow shock. These results are indicative of multiple transport processes taking place on various temporal and spatial scales, and therefore more detailed analysis is required to identify these mechanisms and quantify their contributions to solar wind - magnetosphere coupling. We combine the OMNI, IMAGE and THEMIS observations to statistically examine the properties incident at the magnetopause in the quasi-perpendicular and quasi-parallel shock sides separately. We use local and global MHD simulations to examine the energy and plasma transport properties across the bow shock, in the magnetosheath, and across the magnetopause. We focus especially on the anomalously quiet period during the deep solar minimum in 2008-2010, comparing the results with steady but stronger drivers during magnetic cloud events.

  17. Corotation of an intermittent solar wind source

    NASA Technical Reports Server (NTRS)

    Croft, T. A.

    1972-01-01

    The measured electron content of the solar wind in mid-1970 exhibited a region of relatively high electron density that reappeared at intervals of about 27.8 days. It is shown that the repeating event cannot be reconciled with the concept of a long-enduring steady flow, even though the recurrence period is close to the rotation period of the sun. This evidence of transients is inferred from the short duration of each appearance of the interval of higher density; each should last for roughly one corotation interval if it is caused by a steady stream. The radio path was approximately 0.8 AU long, and the corotation interval exceeded 3 days. Other aspects of the content data patterns support the view that such transient events are common in the solar wind. The mid-1970 repeating event is an unusually good example of the intermittent character of flow regions in the solar wind that fluctuate on a time scale of days but endure as identifiable regions for many months. A sputtering corotating source of thin solar plasma streams could explain this series of events; it could also be explained in terms of a stream that is steady in density and speed but undulating north-south so that it passes into and out of the 0.8 AU radio path in a matter of a day or less.

  18. Response of the Martian environment to solar wind dynamic pressure change

    NASA Astrophysics Data System (ADS)

    Modolo, R.; Leblanc, F.; Chaufray, J. Y.; Curry, S.; Leclercq, L.; Chanteur, G. M.; Savoini, P.

    2014-12-01

    The main structures of the solar wind plasma interaction with the upper atmosphere can be usually described using a steady state picture, however time-dependent effects play important roles. In the last couple of years sophisticated 3D simulation try to address the response of the induced magnetosphere and its escape to different time-dependent drivers. Modolo et al (2012) discussed about timescales required for the induced magnetosphere to recover from an IMF rotation. Ma et al (2013) used time-varying solar wind conditions (density and velocity enhancement) and concluded that the ionospheric/atmospheric system reach a new equilibrium in few hours. We use a 3D parallel multi-species hybrid simulation model to study the response of the induced magnetosphere to a time-varying solar wind dynamic pressure. The hybrid model (Modolo et al, 2014, in prep) includes crustal fields, a ionospheric chemistry scheme and uses a 3D description of the Martian thermosphere (Chaufray et al, 2014) and exosphere (Yagi et al, 2012). The impact of a solar wind dynamic pressure change on plasma boundaries is discussed. A special attention is focused on the time-varying energy deposition in the upper atmosphere by O+ ions precipitation as well as the escape flux of planetary ions.

  19. Characteristics of solar wind density depletions during solar cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Park, K.; Lee, J.; Oh, S.; Yi, Y.

    2014-12-01

    Solar wind density depletions are generally believed to be caused by the interplanetary (IP) shocks. However, there are other cases that are hardly associated with IP shocks. To better understand the cause of the density depletions, we investigate the solar wind parameters and interplanetary magnetic field (IMF) data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the Advanced Composition Explorer (ACE) and the WIND satellite. As a result, we found that the solar wind density has an anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. We thus argue that IMF strength is an important factor in understanding the nature of solar wind density depletion. Since IMF strength varies with solar cycle, we also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an attempt to find its connection to the sun.

  20. Properties of Minor Ions in the Solar Wind and Implications for the Background Solar Wind Plasma

    NASA Technical Reports Server (NTRS)

    Wagner, William (Technical Monitor); Esser, Ruth

    2004-01-01

    The scope of the investigation is to extract information on the properties of the bulk solar wind from the minor ion observations that are provided by instruments on board NASA space craft and theoretical model studies. Ion charge states measured in situ in interplanetary space are formed in the inner coronal regions below 5 solar radii, hence they carry information on the properties of the solar wind plasma in that region. The plasma parameters that are important in the ion forming processes are the electron density, the electron temperature and the flow speeds of the individual ion species. In addition, if the electron distribution function deviates from a Maxwellian already in the inner corona, then the enhanced tail of that distribution function, also called halo, greatly effects the ion composition. This study is carried out using solar wind models, coronal observations, and ion calculations in conjunction with the in situ observations.

  1. Heliolatitude structure of the solar wind proton speed and density at 1 AU for heliospheric modeling

    NASA Astrophysics Data System (ADS)

    Sokol, Justyna Maria; Swaczyna, Pawel; Bzowski, Maciej; Tokumaru, Munetoshi

    2014-05-01

    The heliolatitudinal structure of solar wind proton speed and density varies with solar activity. A model of its variation with time is needed for heliospheric studies and modeling. It is important for the global heliospheric structure, allows for an assessment of ionization rates of neutral species in the heliosphere and interpretation of observations of the energetic neutral atoms and neutral interstellar atoms. Sokół et al. 2013 presented a model of the heliolatitudinal and time variations of solar wind structure based on results of the computer assisted tomography analysis of the solar wind speed enabled by remote-sensing observations of interplanetary scintillations, in-situ measurements from Ulysses, and in-ecliptic measurements from various missions gathered in the OMNI2 database. They determined the 3D structure of solar wind on a yearly time grid from 1990 to 2011. Now we increase the time resolution of the grid used in the model. Because of the weather conditions in Japan, where the interplanetary scintillation observations are carried out, the solar wind data sets contain systematic gaps. For the purposes of the increase of the time resolution of the model for heliospheric studies the method of filling of these gap is needed. We present a comparison of various methods of gap filling. We present results of the investigation of the procedures of reconstruction of the solar wind density with the use of the solar wind invariants published in the literature. Additionally we study various algorithms of extrapolation of the heliolatitudinal time series of the solar wind proton speed and number density in time.

  2. 3D Simulations of the variability of the atmospheric escape at Mars with the EUV solar flux

    NASA Astrophysics Data System (ADS)

    Chaufray, J.-Y.; Leblanc, F.; Modolo, R.; Gonzalez-Galindo, F.; Lopez-Valverde, M.; Forget, F.

    2014-04-01

    The exosphere is the collisionless region surrounding a planetary atmosphere. The exosphere of Mars is an important region to characterize the escape processes. It is mainly formed from processes responsible of the atmospheric escape in the underlying atmosphere/ionosphere. The Martian exosphere is mainly composed of atomic hydrogen, molecular hydrogen and atomic oxygen. Atomic and molecular hydrogen escape is dominated by the thermal escape while the oxygen escape is dominated by the O2+ dissociative recombination in the Martian upper ionosphere. Therefore their escape rates are expected to vary strongly with the EUV solar flux which is the main driver of the heating and ionization of the Martian upper atmosphere. In this presentation, we will present simulations obtained from a 3D Martian exospheric model, coupled to the 3D GCM-LMD model for different solar UV conditions representative of current and past conditions.

  3. Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Riley, Peter

    1999-01-01

    This investigation is concerned with the large-scale evolution and topology of Coronal Mass Ejections (CMEs) in the solar wind. During this reporting period we have analyzed a series of low density intervals in the ACE (Advanced Composition Explorer) plasma data set that bear many similarities to CMEs. We have begun a series of 3D, MHD (Magnetohydrodynamics) coronal models to probe potential causes of these events. We also edited two manuscripts concerning the properties of CMEs in the solar wind. One was re-submitted to the Journal of Geophysical Research.

  4. 3D Lifetime Tomography Reveals How CdCl2 Improves Recombination Throughout CdTe Solar Cells.

    PubMed

    Barnard, Edward S; Ursprung, Benedikt; Colegrove, Eric; Moutinho, Helio R; Borys, Nicholas J; Hardin, Brian E; Peters, Craig H; Metzger, Wyatt K; Schuck, P James

    2017-01-01

    Using two-photon tomography, carrier lifetimes are mapped in polycrystalline CdTe photovoltaic devices. These 3D maps probe subsurface carrier dynamics that are inaccessible with traditional optical techniques. They reveal that CdCl2 treatment of CdTe solar cells suppresses nonradiative recombination and enhances carrier lifetimes throughout the film with substantial improvements particularly near subsurface grain boundaries and the critical buried p-n junction.

  5. 3D Lifetime Tomography Reveals How CdCl 2 Improves Recombination Throughout CdTe Solar Cells

    SciTech Connect

    Barnard, Edward S.; Ursprung, Benedikt; Colegrove, Eric; Moutinho, Helio R.; Borys, Nicholas J.; Hardin, Brian E.; Peters, Craig H.; Metzger, Wyatt K.; Schuck, P. James

    2016-11-15

    Using two-photon tomography, carrier lifetimes are mapped in polycrystalline CdTe photovoltaic devices. These 3D maps probe subsurface carrier dynamics that are inaccessible with traditional optical techniques. They reveal that CdCl2 treatment of CdTe solar cells suppresses nonradiative recombination and enhances carrier lifetimes throughout the film with substantial improvements particularly near subsurface grain boundaries and the critical buried p-n junction.

  6. Deimos: an obstacle to the solar wind.

    PubMed

    Sauer, K; Dubinin, E; Baumgärtel, K; Bogdanov, A

    1995-08-25

    Two isolated solar wind disturbances about 5 minutes in duration were detected aboard the Russian spacecraft Phobos-2 upon its crossing the wake of the martian moon Deimos about 15,000 kilometers downstream from the moon on 1 February 1989. These plasma and magnetic events are interpreted as the inbound and outbound crossings of a Mach cone that is formed as a result of an effective interaction of the solar wind with Deimos. Possible mechanisms such as remanent magnetization, cometary type interaction caused by heavy ion or charged dust production, and unipolar induction resulting from the finite conductivity of the body are discussed. Although none of the present models is fully satisfactory, neutral gas emission through water loss by Deimos at a rate of about 10(23) molecules per second, combined with a charged dust coma, is favored.

  7. Solar wind thermally induced magnetic fluctuations.

    PubMed

    Navarro, R E; Moya, P S; Muñoz, V; Araneda, J A; F-Viñas, A; Valdivia, J A

    2014-06-20

    A kinetic description of Alfvén-cyclotron magnetic fluctuations for anisotropic electron-proton quasistable plasmas is studied. An analytical treatment, based on the fluctuation-dissipation theorem, consistently shows that spontaneous fluctuations in plasmas with stable distributions significantly contribute to the observed magnetic fluctuations in the solar wind, as seen, for example, in [S. D. Bale et al., Phys. Rev. Lett. 103, 211101 (2009)], even far below from the instability thresholds. Furthermore, these results, which do not require any adjustable parameters or wave excitations, are consistent with the results provided by hybrid simulations. It is expected that this analysis contributes to our understanding of the nature of magnetic fluctuations in the solar wind.

  8. Anisotropy in solar wind plasma turbulence.

    PubMed

    Oughton, S; Matthaeus, W H; Wan, M; Osman, K T

    2015-05-13

    A review of spectral anisotropy and variance anisotropy for solar wind fluctuations is given, with the discussion covering inertial range and dissipation range scales. For the inertial range, theory, simulations and observations are more or less in accord, in that fluctuation energy is found to be primarily in modes with quasi-perpendicular wavevectors (relative to a suitably defined mean magnetic field), and also that most of the fluctuation energy is in the vector components transverse to the mean field. Energy transfer in the parallel direction and the energy levels in the parallel components are both relatively weak. In the dissipation range, observations indicate that variance anisotropy tends to decrease towards isotropic levels as the electron gyroradius is approached; spectral anisotropy results are mixed. Evidence for and against wave interpretations and turbulence interpretations of these features will be discussed. We also present new simulation results concerning evolution of variance anisotropy for different classes of initial conditions, each with typical background solar wind parameters.

  9. The solar wind and magnetospheric dynamics

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1974-01-01

    The dynamic processes involved in the interaction between the solar wind and the earth's magnetosphere are reviewed. The evolution of models of the magnetosphere is first surveyed. The existence of the auroral substorm and the cyclical polar magnetic substorm is evidence that the magnetosphere is a dynamic system. The dynamic changes occurring in the magnetosphere, including erosion of the magnetopause, changes in the size of the polar cap, variations in the flaring angle of the tail, neutral point formation, plasma sheet motions, and the inward collapse of the midnight magnetosphere, are discussed. The cyclical variations of geomagnetic activity are explained in terms of the control of the solar wind-magnetosphere interaction by the north-south component of the interplanetary magnetic field. Present phenomenological models allow prediction of geomagnetic activity from interplanetary measurements, but modeling of detailed magnetospheric processes is still in its infancy.

  10. Corona-Solar Wind Coupling Review

    DTIC Science & Technology

    1987-06-01

    Spitzer which should be valid if the magne:ic field is radial and the plasma is collision dominated. Although both of these conditions are expected to hold...conduction has been studied by introducing a heat flux density given by the classical Spitzer value times the square of the cosine of the angle...Broussard, R. M., N. R. Shecley, Jr ., R. Tousey, and J. H. Underwood. A survey of coronal holes and their solar wind associations throughout sunspot cycle

  11. Turbulence and waves in the solar wind

    SciTech Connect

    Roberts, D.A.; Goldstein, M.L. )

    1991-01-01

    Studies of turbulence and waves in the solar wind is discussed. Consideration is given to the observations and theory concerning the origin and evolution of interplanetary MHD fluctuations and to the observations, theory, and simulations of compressive fluctuations. Particular attention is given to extrapolations to near-sun and polar fields regions. Results obtained on turbulence at comets and magnetic turbulence of low-frequency waves excited by unstable distributions of ions are discussed. 230 refs.

  12. High Sensitive Precise 3D Accelerometer for Solar System Exploration with Unmanned Spacecrafts

    NASA Astrophysics Data System (ADS)

    Savenko, Y. V.; Demyanenko, P. O.; Zinkovskiy, Y. F.

    Solutions of several space and geophysical tasks require creating high sensitive precise accelerometers with sensitivity in order of 10 -13 g. These several tasks are following: inertial navigation of the Earth and Space; gravimetry nearby the Earth and into Space; geology; geophysics; seismology etc. Accelerometers (gravimeters and gradientmeters) with required sensitivity are not available now. The best accelerometers in the world have sensitivity worth on 4-5 orders. It has been developed a new class of fiber-optical sensors (FOS) with light pulse modulation. These sensors have super high threshold sensitivity and wide (up to 10 orders) dynamic range, and can be used as a base for creating of measurement units of physical values as 3D superhigh sensitive precise accelerometers of linear accelerations that is suitable for highest requirements. The principle of operation of the FOS is organically combined with a digital signal processing. It allows decreasing hardware of the accelerometer due to using a usual air-borne or space-borne computer; correcting the influence of natural, design, technological drawbacks of FOS on measured results; neutralising the influence of extraordinary situations available during using of FOS; decreasing the influence of internal and external destabilising factors (as for FOS), such as oscillation of environment temperature, instability of pendulum cycle frequency of sensitive element of the accelerometer etc. We were conducted a quantitative estimation of precise opportunities of analogue FOS in structure of fiber optical measuring devices (FOMD) for elementary FOMD with analogue FOS built on modern element basis of fiber optics (FO), at following assumptions: absolute parameter stability of devices of FOS measuring path; single transmission band of registration path; maximum possible inserted in optical fiber (OF) a radiated power. Even at such idealized assumptions, a calculated value in limit reached minimum inaccuracy of

  13. Quasi-steady solar wind dynamics

    NASA Technical Reports Server (NTRS)

    Pizzo, V. J.

    1983-01-01

    Progress in understanding the large scale dynamics of quasisteady, corotating solar wind structure was reviewed. The nature of the solar wind at large heliocentric distances preliminary calculations from a 2-D MHD model are used to demonstrate theoretical expectations of corotating structure out to 30 AU. It is found that the forward and reverse shocks from adjacent CIR's begin to interact at about 10 AU, producing new shock pairs flanking secondary CIR's. These sawtooth secondary CIR's interact again at about 20 AU and survive as visible entities to 30 AU. The model predicts the velocity jumps at the leading edge of the secondary CIR's at 30 AU should be very small but there should still be sizable variations in the thermodynamic and magnetic parameters. The driving dynamic mechanism in the distant solar wind is the relaxation of pressure gradients. The second topic is the influence of weak, nonimpulsive time dependence in quasisteady dynamics. It is suggested that modest large scale variations in the coronal flow speed on periods of several hours to a day may be responsible for many of the remaining discrepancies between theory and observation. Effects offer a ready explanation for the apparent rounding of stream fronts between 0.3 and 1.0 AU discovered by Helios.

  14. Solar Wind Charge Exchange During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  15. Western Wind and Solar Integration Study (Fact Sheet)

    SciTech Connect

    Not Available

    2012-09-01

    Initiated in 2007 to examine the operational impact of up to 35% penetration of wind, photovoltaic (PV), and concentrating solar power (CSP) energy on the electric power system, the Western Wind and Solar Integration Study (WWSIS) is one of the largest regional wind and solar integration studies to date. The goal is to understand the effects of variability and uncertainty of wind, PV, and CSP on the grid. In the Western Wind and Solar Integration Study Phase 1, solar penetration was limited to 5%. Utility-scale PV was not included because of limited capability to model sub-hourly, utility-scale PV output . New techniques allow the Western Wind and Solar Integration Study Phase 2 to include high penetrations of solar - not only CSP and rooftop PV but also utility-scale PV plants.

  16. Solar wind and its interaction with the magnetosphere - Measured parameters

    NASA Astrophysics Data System (ADS)

    Schwenn, R.

    The sun and the solar wind are considered in terms of the 'ballerina' model first proposed by Alfven (1977), taking into account high speed streams, the slow solar wind, stream-stream interactions, the relation of streams and magnetic structure, and transients caused by solar activity. The main features of the solar wind behavior are illustrated with the aid of data, covering one complete solar rotation in 1974/1975, which were obtained with instruments aboard the Helios-1 solar probe. It is pointed out that the solar wind acts like a huge buffer pushing onto the earth's magnetosphere with a highly variable pressure. Of the energy in the highly variable solar wind reservoir only a tiny fraction is absorbed by the magnetosphere in an obviously very nonstationary way.

  17. New light-trapping concept by means of several optical components applied to compact holographic 3D concentration solar module

    NASA Astrophysics Data System (ADS)

    Villamarín Villegas, Ayalid M.; Pérez López, Francisco J.; Calo López, Antonio; Rodríguez San Segundo, Hugo-José

    2014-05-01

    A new light-trapping concept is presented, which joins broad bandwidth volume phase reflection holograms (VPRH) working together with three other optical components: specifically designed three-dimensional (3D) cavities, Total Internal Reflection (TIR) within an optical medium, and specular reflection by means of a highly reflective surface. This concept is applied to the design and development of both low concentration photovoltaic (LCPV) and solar thermal modules reaching a concentration factor of up to 3X. Higher concentrations are feasible for use in concentrated solar power (CSP) devices. The whole system is entirely made of polymeric materials (except for the solar cells or fluid carrying pipes), thus reducing cost by up to 40%. The module concentrates solar light onto solar cells - or fluid carrying pipes - with no need for active tracking of the sun, covering the whole seasonal and daily incident angle spectrum while it also minimizes optical losses. In this work we analyze the first experimentally measured optical characteristics and performance of VPRH in dichromated gelatin film (DCG) in our concept. The VPRH can reach high diffraction efficiencies (˜98%, ignoring Fresnel reflection losses). Thanks to specifically designed raw material, coating and developing process specifications, also very broad selective spectral (higher than 300 nm) and angular bandwidths (˜+20º) per grating are achieved. The VPRH was optimized to use silicon solar cells, but designs for other semiconductor devices or for fluid heating are feasible. The 3D shape, the hologram's and reflective surface's optical quality, the TIR effect and the correct coupling of all the components are key to high performance of the concentration solar module.

  18. Electron energy flux in the solar wind.

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Scudder, J. D.; Sugiura, M.

    1971-01-01

    Description of studies of electrons between 10 eV and 9.9 keV in the solar wind. The transport of energy in the rest frame of the plasma is evaluated and shown to be parallel to the interplanetary magnetic field. The presence of electrons from solar events causes this energy-flux density to exceed the heat flow due to thermal electrons. In one such event, the observations are shown to be consistent with the solar-electron observations made at higher energies. When observations are made at a point connected to the earth's bow shock by an interplanetary-field line, a comparatively large energy flux along the field toward the sun is observed, but the heat flow remains outwardly directed during this time interval. In either situation the heat flow is found to be consistent with measurements made on Vela satellites by a different method. These values, less than .01 ergs/sq cm/sec, are sufficiently low to require modifications to the Spitzer-Harm conductivity formula for use in solar-wind theories.

  19. Solar Wind Interaction with Lunar Magnetic Anomalies: Reiner Gamma

    NASA Astrophysics Data System (ADS)

    Deca, Jan; Divin, Andrey; Wang, Xu; Lembège, Bertrand; Markidis, Stefano; Lapenta, Giovanni; Horányi, Mihály

    2016-04-01

    Discovered by early astronomers during the Renaissance, the Reiner Gamma formation is one of the most peculiar lunar surface features. Observations have shown that the tadpole-shaped albedo marking, the so-called swirl, found on the Oceanus Procellarum is co-located with one of the strongest magnetic anomalies (LMA) on our Moon. In previous work, using a horizontal dipole model [Deca et al. 2014, 2015], we have described the formation of a mini-magnetosphere structure surrounding the swirl pattern, locally shielding the underlying lunar surface from the impinging solar wind, and hinting at a correlation with its main surface albedo brightness marking in a distinctive concentric oval shape. Using the observed magnetic field model [Tsunakawa et al. 2015] in our full-kinetic electromagnetic framework, iPic3D, we reproduce a surface weathering pattern closely resembling the details of the Reiner Gamma swirls. This work therefore provides strong evidence that the solar wind standoff theory for lunar swirl formation is the dominant process to explain the albedo markings of the Reiner Gamma region. This work was supported by NASA's SSSERVI/IMPACT and by the Swedish National Space Board, Grant No. 136/11. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. Test simulations utilised the Janus supercomputer, supported by NSF (CNS-0821794) and CU Boulder.

  20. Solar radiation transport in the cloudy atmosphere: a 3D perspective on observations and climate impacts

    NASA Astrophysics Data System (ADS)

    Davis, Anthony B.; Marshak, Alexander

    2010-02-01

    The interplay of sunlight with clouds is a ubiquitous and often pleasant visual experience, but it conjures up major challenges for weather, climate, environmental science and beyond. Those engaged in the characterization of clouds (and the clear air nearby) by remote sensing methods are even more confronted. The problem comes, on the one hand, from the spatial complexity of real clouds and, on the other hand, from the dominance of multiple scattering in the radiation transport. The former ingredient contrasts sharply with the still popular representation of clouds as homogeneous plane-parallel slabs for the purposes of radiative transfer computations. In typical cloud scenes the opposite asymptotic transport regimes of diffusion and ballistic propagation coexist. We survey the three-dimensional (3D) atmospheric radiative transfer literature over the past 50 years and identify three concurrent and intertwining thrusts: first, how to assess the damage (bias) caused by 3D effects in the operational 1D radiative transfer models? Second, how to mitigate this damage? Finally, can we exploit 3D radiative transfer phenomena to innovate observation methods and technologies? We quickly realize that the smallest scale resolved computationally or observationally may be artificial but is nonetheless a key quantity that separates the 3D radiative transfer solutions into two broad and complementary classes: stochastic and deterministic. Both approaches draw on classic and contemporary statistical, mathematical and computational physics.

  1. Solar Radiation Transport in the Cloudy Atmosphere: A 3D Perspective on Observations and Climate Impacts

    NASA Technical Reports Server (NTRS)

    Davis, Anthony B.; Marshak, Alexander

    2010-01-01

    The interplay of sunlight with clouds is a ubiquitous and often pleasant visual experience, but it conjures up major challenges for weather, climate, environmental science and beyond. Those engaged in the characterization of clouds (and the clear air nearby) by remote sensing methods are even more confronted. The problem comes, on the one hand, from the spatial complexity of real clouds and, on the other hand, from the dominance of multiple scattering in the radiation transport. The former ingredient contrasts sharply with the still popular representation of clouds as homogeneous plane-parallel slabs for the purposes of radiative transfer computations. In typical cloud scenes the opposite asymptotic transport regimes of diffusion and ballistic propagation coexist. We survey the three-dimensional (3D) atmospheric radiative transfer literature over the past 50 years and identify three concurrent and intertwining thrusts: first, how to assess the damage (bias) caused by 3D effects in the operational 1D radiative transfer models? Second, how to mitigate this damage? Finally, can we exploit 3D radiative transfer phenomena to innovate observation methods and technologies? We quickly realize that the smallest scale resolved computationally or observationally may be artificial but is nonetheless a key quantity that separates the 3D radiative transfer solutions into two broad and complementary classes: stochastic and deterministic. Both approaches draw on classic and contemporary statistical, mathematical and computational physics.

  2. Topological Origins of the Slow Solar Wind

    NASA Astrophysics Data System (ADS)

    Antiochos, S.

    2008-12-01

    Although the slow solar wind has been studied for decades with both in situ and remote sensing observations, its origin is still a matter of intense debate. In the standard quasi-steady model, the slow wind is postulated to originate near coronal hole boundaries that define topologically well-behaved separatrices between open and closed field regions. In the interchange model, on the other hand, the slow wind is postulated to originate on open flux that is dynamically diffusing throughout the seemingly closed-field corona. We argue in favor of the quasi-steady scenario and propose that the slow wind is due to two effects: First, the open-closed boundary is highly complex due to the complexity of the photospheric flux distribution. Second, this boundary is continuously driven by the transport of magnetic helicity from the closed field region into the open. The implications of this model for the structure and dynamics of the corona and slow wind are discussed, and observational tests of the model are presented. This work has been supported, in part, by the NASA LWS, HTP, and SR&T programs.

  3. Topological Origins of the Slow Solar Wind

    NASA Technical Reports Server (NTRS)

    Antiochos, Spiro

    2008-01-01

    Although the slow solar wind has been studied for decades with both in situ and remote sensing observations, its origin is still a matter of intense debate. In the standard quasi-steady model, the slow wind is postulated to originate near coronal hole boundaries that define topologically well-behaved separatrices between open and closed field regions. In the interchange model, on the other hand, the slow wind is postulated to originate on open flux that is dynamically diffusing throughout the seemingly closed-field corona. We argue in favor of the quasi-steady scenario and propose that the slow wind is due to two effects: First, the open-closed boundary is highly complex due to the complexity of the photospheric flux distribution. Second, this boundary is continuously driven by the transport of magnetic helicity from the closed field region into the open. The implications of this model for the structure and dynamics of the corona and slow wind are discussed, and observational tests of the mode

  4. Coronal Holes and Solar Wind High-Speed Streams: I. Forecasting the Solar Wind Parameters

    NASA Astrophysics Data System (ADS)

    Vršnak, Bojan; Temmer, Manuela; Veronig, Astrid M.

    2007-02-01

    We analyze the relationship between the coronal hole (CH) area/position and physical characteristics of the associated corotating high-speed stream (HSS) in the solar wind at 1 AU. For the analysis we utilize the data in the period DOY 25 125 of 2005, characterized by a very low coronal mass ejection (CME) activity. Distinct correlations between the daily averaged CH parameters and the solar wind characteristics are found, which allows us to forecast the solar wind velocity v, proton temperature T, proton density n, and magnetic field strength B, several days in advance in periods of low CME activity. The forecast is based on monitoring fractional areas A, covered by CHs in the meridional slices embracing the central meridian distance ranges [-40°,-20°], [-10°,10°], and [20°,40°]. On average, the peaks in the daily values of n, B, T, and v appear delayed by 1, 2, 3, and 4 days, respectively, after the area A attains its maximum in the central-meridian slice. The peak values of the solar wind parameters are correlated to the peak values of A, which provides also forecasting of the peak values of n, B, T, and v. The most accurate prediction can be obtained for the solar wind velocity, for which the average relative difference between the calculated and the observed peak values amounts to overline{\\vertδ\\vert}≈10 %. The forecast reliability is somewhat lower in the case of T, B, and n ( overline{\\vertδ\\vert}≈20 , 30, and 40%, respectively). The space weather implications are discussed, including the perspectives for advancing the real-time calculation of the Sun Earth transit times of coronal mass ejections and interplanetary shocks, by including more realistic real-time estimates of the solar wind characteristics.

  5. Variations of the solar wind and solar cycle in the last 300 years

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Silverman, S.

    1980-01-01

    The past history of the solar wind and solar cycle, inferred from records of geomagnetics and aurora, is examined. Records show that the solar wind apparently varied in a systematic manner throughout the period from 1770 to 1857 and that the period around 1810 resembled the 1901 minimum geomagnetic disturbance. Results show that the solar wind and hence the Sun changes on a time scale long compared to a solar cycle and short compared to the Maunder minimum. The inclusion of a study on the solar wind and solar cycle variations for the SCADM mission is discussed.

  6. ISOTOPIC MASS FRACTIONATION OF SOLAR WIND: EVIDENCE FROM FAST AND SLOW SOLAR WIND COLLECTED BY THE GENESIS MISSION

    SciTech Connect

    Heber, Veronika S.; Baur, Heinrich; Wieler, Rainer; Bochsler, Peter; McKeegan, Kevin D.; Neugebauer, Marcia; Reisenfeld, Daniel B.; Wiens, Roger C.

    2012-11-10

    NASA's Genesis space mission returned samples of solar wind collected over {approx}2.3 years. We present elemental and isotopic compositions of He, Ne, and Ar analyzed in diamond-like carbon targets from the slow and fast solar wind collectors to investigate isotopic fractionation processes during solar wind formation. The solar wind provides information on the isotopic composition for most volatile elements for the solar atmosphere, the bulk Sun and hence, on the solar nebula from which it formed 4.6 Ga ago. Our data reveal a heavy isotope depletion in the slow solar wind compared to the fast wind composition by 63.1 {+-} 2.1 per mille for He, 4.2 {+-} 0.5 per mille amu{sup -1} for Ne and 2.6 {+-} 0.5 per mille amu{sup -1} for Ar. The three Ne isotopes suggest that isotopic fractionation processes between fast and slow solar wind are mass dependent. The He/H ratios of the collected slow and fast solar wind samples are 0.0344 and 0.0406, respectively. The inefficient Coulomb drag model reproduces the measured isotopic fractionation between fast and slow wind. Therefore, we apply this model to infer the photospheric isotopic composition of He, Ne, and Ar from our solar wind data. We also compare the isotopic composition of oxygen and nitrogen measured in the solar wind with values of early solar system condensates, probably representing solar nebula composition. We interpret the differences between these samples as being due to isotopic fractionation during solar wind formation. For both elements, the magnitude and sign of the observed differences are in good agreement with the values predicted by the inefficient Coulomb drag model.

  7. Interpretation of solar irradiance monitor measurements through analysis of 3D MHD simulations

    SciTech Connect

    Criscuoli, S.; Uitenbroek, H.

    2014-06-20

    Measurements from the Spectral Irradiance Monitor (SIM) on board the Solar Radiation and Climate Experiment mission indicate that solar spectral irradiance at visible and IR wavelengths varies in counter phase with the solar activity cycle. The sign of these variations is not reproduced by most of the irradiance reconstruction techniques based on variations of surface magnetism employed so far, and it is not yet clear whether SIM calibration procedures need to be improved or if instead new physical mechanisms must be invoked to explain such variations. We employ three-dimensional magnetohydrodynamic simulations of the solar photosphere to investigate the dependence of solar radiance in SIM visible and IR spectral ranges on variations of the filling factor of surface magnetic fields. We find that the contribution of magnetic features to solar radiance is strongly dependent on the location on the disk of the features, which are negative close to disk center and positive toward the limb. If features are homogeneously distributed over a region around the equator (activity belt), then their contribution to irradiance is positive with respect to the contribution of HD snapshots, but decreases with the increase of their magnetic flux for average magnetic flux larger than 50 G in at least two of the visible and IR spectral bands monitored by SIM. Under the assumption that the 50 G snapshots are representative of quiet-Sun regions, we thus find that the Spectral Irradiance can be in counter-phase with the solar magnetic activity cycle.

  8. Steady state asymmetric planetary electrical induction. [by solar wind

    NASA Technical Reports Server (NTRS)

    Horning, B. L.; Schubert, G.

    1974-01-01

    An analytic solution is presented for the steady state electric and magnetic fields induced by the motional electric field of the solar wind in the atmosphere or interior of a planet that is asymmetrically surrounded by solar wind plasma. The electrically conducting ionosphere or interior must be in direct electrical contact with the solar wind over the day side of the planet. The conducting region of the planet is modeled by a sphere or a spherical shell of arbitrarily stratified electrical conductivity. A monoconducting cylindrical cavity is assumed to extend downstream on the night side of the planet. The solar wind is assumed to be highly conducting so that the induced fields are confined to the planet and cavity. Induced currents close as sheet currents at the solar wind-cavity and solar wind-planet interfaces. Numerical evaluations of the analytic formulas are carried out for a uniformly conducting spherical model.

  9. Variations of Strahl Properties with Fast and Slow Solar Wind

    NASA Technical Reports Server (NTRS)

    Figueroa-Vinas, Adolfo; Goldstein, Melvyn L.; Gurgiolo, Chris

    2008-01-01

    The interplanetary solar wind electron velocity distribution function generally shows three different populations. Two of the components, the core and halo, have been the most intensively analyzed and modeled populations using different theoretical models. The third component, the strahl, is usually seen at higher energies, is confined in pitch-angle, is highly field-aligned and skew. This population has been more difficult to identify and to model in the solar wind. In this work we make use of the high angular, energy and time resolution and three-dimensional data of the Cluster/PEACE electron spectrometer to identify and analyze this component in the ambient solar wind during high and slow speed solar wind. The moment density and fluid velocity have been computed by a semi-numerical integration method. The variations of solar wind density and drift velocity with the general build solar wind speed could provide some insight into the source, origin, and evolution of the strahl.

  10. Solar wind rare gas analysis: Trapped solar wind helium and neon in Surveyor 3 material

    NASA Technical Reports Server (NTRS)

    Buehler, F.; Eberhardt, P.; Geiss, J.; Schwarzmueller, J.

    1972-01-01

    The He-4 and Ne-20 contents in sections of the Surveyor 3 support strut samples were determined by optical and scanning electron microscopy and are compared to the results of the Apollo solar wind composition (SWC) experiments. The He-4/Ne-20 ratio in the samples from the sunlit side of the strut was approximately 300; the ratios determined in Apollo 12 lunar fines and SWC foil were below 100. The He-4/He-3 ratios were also determined, and the ratio obtained from Surveyor 3 material is higher than those found with Apollo 11 and 12 SWC experiments. The effects of spallation by cosmic rays or solar protons, stripping by cosmic ray or energetic solar alpha particles, recycling of solar wind He and radiogenic Ne, He from terrestrial atmosphere, mass discrimination near the moon, mass dependence of trapping probability, diffusion, and contamination by lunar dust are considered.

  11. Initial Comparison Between a 3D MHD Model and the HAFv2 Kinematic 3D Model: The October/November 2003 Events from the Sun to 6 AU

    SciTech Connect

    Intriligator, Devrie S.; Detman, Thomas; Fry, Craig D.; Sun Wei; Deehr, Charles; Intriligator, James

    2005-08-01

    A first-generation 3D kinematic, space weather forecasting solar wind model (HAFv2) has been used to show the importance of solar generated disturbances in Voyager 1 and Voyager 2 observations in the outer heliosphere. We extend this work by using a 3D MHD model (HHMS) that, like HAFv2, incorporates a global, pre-event, inhomogeneous, background solar wind plasma and interplanetary magnetic field. Initial comparisons are made between the two models of the solar wind out to 6 AU and with in-situ observations at the ACE spacecraft before and after the October/November 2003 solar events.

  12. Three-dimensional global MHD modeling of a coronal mass ejection interacting with the solar wind

    NASA Astrophysics Data System (ADS)

    An, J.; Inoue, S.; Magara, T.; Lee, H.; Kang, J.; Hayashi, K.; Tanaka, T.; Den, M.

    2013-12-01

    We developed a three-dimensional (3D) magnetohydrodynamic (MHD) code to reproduce the structure of the solar wind, the propagation of a coronal mass ejection (CME), and the interaction between them. This MHD code is based on the finite volume method and total diminishing (TVD) scheme with an unstructured grid system. In particular, this grid system can avoid the singularity at the north and south poles and relax tight CFL conditions around the poles, both of which would arise in the spherical coordinate system (Tanaka 1995). In this study, we constructed a model of the solar wind driven by the physical values at 50 solar radii obtained from the MHD tomographic method (Hayashi et al. 2003) where an interplanetary scintillation (IPS) observational data is used. By comparing the result to the observational data obtained from the near-Earth OMNI dataset, we confirmed that our simulation reproduces the velocity, temperature and density profiles obtained from the near-Earth OMNI dataset. We then insert a spheromak-type CME (Kataoka et al. 2009) into our solar-wind model and investigate the propagation process of the CME interacting with the solar wind. In particular, we discuss how the magnetic twist accumulated in a CME affects the CME-solar wind interaction.

  13. Radial evolution of the energy density of solar wind fluctuations

    NASA Technical Reports Server (NTRS)

    Zank, G. P.; Matthaeus, W. H.; Smith, C. W.

    1995-01-01

    On the basis of transport theories appropriate to a radially expanding solar wind, we describe new results for the radial evolution of the energy density in solar wind fluctuations at MHD scales. These models include the effects of 'mixing' and driving as well as the possibility of non-isotropic MHD turbulence. Implications of these results for solar wind heating, cosmic ray diffusion and interstellar pick-up ions will also be addressed.

  14. Morphology of Pseudostreamers and Solar Wind Properties

    NASA Astrophysics Data System (ADS)

    Panasenco, Olga; Velli, Marco

    2016-05-01

    The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop the specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates the conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Middle-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers (PSs) if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of PSs shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at the PS base low in the corona.

  15. 3-d modeling of the middle and upper atmosphere response to the 27-day solar variation

    NASA Astrophysics Data System (ADS)

    Gruzdev, A.; Schmidt, H.; Brasseur, G.

    We present results of an analysis of the effect of the 27-day solar variation on composition and temperature of the stratosphere mesosphere and lower thermosphere calculated with the 3-dimensional chemistry climate model HAMMONIA The spectral amplitudes of the 27-day solar cycle within the wavelength range from Lyman-a to the short infrared which are input parameters at the upper boundary of the model were calculated from data of UARS SOLSTICE measurements A combination of high resolution spectral and cross-spectral analyses allows determining 27-day variations in the Earth atmosphere which are related to the 27-day solar forcing These methods give also estimates of the amplitude and hence sensitivity and phase of the response While the calculated thermal and chemical responses are very distinct and permanent in the upper atmosphere the responses in the stratosphere and mesosphere are intermittent in time and affected as well by interannual variability It is due to interference of the inherent atmospheric variability and the variability forced by the 27-day solar cycle which sophisticates the response to the 27-day solar forcing in large parts of the model stratosphere and mesosphere In the extratropical latitudes the responses are seasonally dependent Altitude-latitude distributions of sensitivities and phases of the responses to the 27-day solar forcing are analyzed in detail for temperature and chemical species important for ozone chemistry The sensitivity and phase of the ozone response in the tropical stratosphere and lower mesosphere are in satisfactory

  16. What Determines the Solar Wind Speed ?

    NASA Astrophysics Data System (ADS)

    Suzuki, T. K.; Fujiki, K.; Kojima, M.; Tokumaru, M.; Hirano, M.; Baba, D.; Yamasita, M.; Hakamada, K.

    2005-05-01

    Recent observations by Interplanetary Scintillation measurements by Nagoya-STEL group (Hirano et al.2003; Kojima et al.2004) show that solar wind speed is well-correlated with B/f, where B is radial magnetic field strength at the solar surface and f is a super-radial expansion factor of open flux tubes. We show that this correlation is nicely explained by dissipation of Alfven waves no matter what types of the wave dissipation processes operate. B determines the input energy flux of Alfven waves and f controls adiabatic loss of the wave energy, so that B/f is an important control parameter which determines the solar wind speed. (reference ) [1] Hirano, M., Kojima, M., Tokumaru, M., Fujiki, K., Ohmi, T., Yamashita, M, Hakamada, K., and Hayashi, K. 2003,, Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract SH21B-0164 [2] Kojima, M., K. Fujiki, M. Hirano, M. Tokumaru, T. Ohmi, and K. Hakamada, 2004, "The Sun and the heliosphere as an Integrated System", Giannina Poletto and Steven T. Suess, Eds. Kluwer Academic Publishers, in press

  17. Solar wind influence on Jupiter's magnetosphere and aurora

    NASA Astrophysics Data System (ADS)

    Vogt, Marissa; Gyalay, Szilard; Withers, Paul

    2016-04-01

    Jupiter's magnetosphere is often said to be rotationally driven, with strong centrifugal stresses due to large spatial scales and a rapid planetary rotation period. For example, the main auroral emission at Jupiter is not due to the magnetosphere-solar wind interaction but is driven by a system of corotation enforcement currents that arises to speed up outflowing Iogenic plasma. Additionally, processes like tail reconnection are also thought to be driven, at least in part, by processes internal to the magnetosphere. While the solar wind is generally expected to have only a small influence on Jupiter's magnetosphere and aurora, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the position and brightness of the UV auroral emissions. We will report on the results of a comprehensive, quantitative study of the influence of the solar wind on various magnetospheric data sets measured by the Galileo mission from 1996 to 2003. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter, we have identified intervals of high and low solar wind dynamic pressure. We can use this information to quantify how a magnetospheric compression affects the magnetospheric field configuration, which in turn will affect the ionospheric mapping of the main auroral emission. We also consider whether there is evidence that reconnection events occur preferentially during certain solar wind conditions or that the solar wind modulates the quasi-periodicity seen in the magnetic field dipolarizations and flow bursts.

  18. CdS sensitized 3D hierarchical TiO2/ZnO heterostructure for efficient solar energy conversion.

    PubMed

    Zheng, Zhaoke; Xie, Wen; Lim, Zhi Shiuh; You, Lu; Wang, Junling

    2014-07-17

    For conventional dye or quantum dot sensitized solar cells, which are fabricated using mesoporous films, the inefficient electron transport due to defects such as grain boundaries and surface traps is a major drawback. To simultaneously increase the carrier transport efficiency as well as the surface area, optimal-assembling of hierarchical nanostructures is an attractive approach. Here, a three dimensional (3D) hierarchical heterostructure, consisting of CdS sensitized one dimensional (1D) ZnO nanorods deposited on two dimensional (2D) TiO2 (001) nanosheet, is prepared via a solution-process method. Such heterstructure exhibits significantly enhanced photoelectric and photocatalytic H2 evolution performance compared with CdS sensitized 1D ZnO nanorods/1D TiO2 nanorods photoanode, as a result of the more efficient light harvesting over the entire visible light spectrum and the effective electron transport through a highly connected 3D network.

  19. CdS sensitized 3D hierarchical TiO2/ZnO heterostructure for efficient solar energy conversion

    PubMed Central

    Zheng, Zhaoke; Xie, Wen; Lim, Zhi Shiuh; You, Lu; Wang, Junling

    2014-01-01

    For conventional dye or quantum dot sensitized solar cells, which are fabricated using mesoporous films, the inefficient electron transport due to defects such as grain boundaries and surface traps is a major drawback. To simultaneously increase the carrier transport efficiency as well as the surface area, optimal-assembling of hierarchical nanostructures is an attractive approach. Here, a three dimensional (3D) hierarchical heterostructure, consisting of CdS sensitized one dimensional (1D) ZnO nanorods deposited on two dimensional (2D) TiO2 (001) nanosheet, is prepared via a solution-process method. Such heterstructure exhibits significantly enhanced photoelectric and photocatalytic H2 evolution performance compared with CdS sensitized 1D ZnO nanorods/1D TiO2 nanorods photoanode, as a result of the more efficient light harvesting over the entire visible light spectrum and the effective electron transport through a highly connected 3D network. PMID:25030846

  20. The ISPM solar-wind ion composition spectrometer

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.; Geiss, J.; Balsiger, H.; Fisk, L. A.; Gliem, F.; Ipavich, F. M.; Ogilvie, K. W.; Stuedemann, W.; Wilken, B.

    1983-01-01

    The International Solar Polar Mission (ISPM) Solar-Wind Ion Composition Spectrometer which determines elemental and ionic-charge composition, and the temperatures and mean speeds of all major solar-wind ions, from H through Fe, at solar wind speeds ranging from 145 km/sec (protons) to 1352 km/sec (Fe+8) is described. The instrument, which covers an energy per charge range from 110 eV/q to 66.7 keV/q in 13 min, combines an electrostatic analyzer with postacceleration, followed by a time-of-flight and energy measurement. Conditions and processes in the region of the corona where the solar wind is accelerated; location of the source regions of the solar wind in the corona; coronal heating processes; the extent and causes of variations in the composition of the solar atmosphere; plasma processes in the solar wind; acceleration of energetic particles in the solar wind; the thermalization and acceleration of interstellar ions in the solar wind, and their composition; and the composition and behavior of the plasma in the Jovian magnetosphere are studied.

  1. Time Variable Solar Wind Interaction of Mercury

    NASA Astrophysics Data System (ADS)

    Ip, W.-H.; Kopp, A.

    A three-dimensional MHD code was used to simulate the solr wind interaction of Mercury's magnetosphere with interplanetary magnetic field (IMF) of different orien- tations. It can be shown that for northward pointing IMF, the Hermean magnetosphere is nearly closed with the polar cap shrinking to a small area. On the other hand, the boundary of the polar cap expands to mid-latitude region (about 30 degrees latitude) for south-pointing IMF. Such large changes in the size and morphology of the polar cap in response to directional variations of the IMF could be related to the observed temporal variabilities of the atomic sodium emission on Mercury's disk. That is, the production rate of the sodium atoms could be significantly modulated i.e., weak for northward IMF and large for southward IMF) if solar wind sputtering of the surface material is an important source mechanism of the sodium atoms.

  2. Estimation of Solar Energy on Vertical 3D Building Walls on City Quarter Scale

    NASA Astrophysics Data System (ADS)

    Jaugsch, F.; Löwner, M.-O.

    2016-10-01

    In urban areas, solar energy is one promising source of renewable energy to achieve the EU parliament's goal of reducing CO2 emissions by 20 % compared to 1990. Although annual radiation on vertical walls is lower than that on roof surfaces, they are larger in area and, therefore may contribute to energy production. On the other hand, the modelling of shadowing effects is cost intensive in an complex urban environment. Here we present a method for the calculation of solar potential on vertical walls for simple 2D maps with additional building height information. We introduced observer point columns that enable a fast decision whether a whole vertical set of observer points is illuminated or not. By the introduction of a maximum shade length, we reduce processing time in ArcGIS. 206,291 points of 130 buildings have been analysed in time steps of 15 minutes resulting in 15 769 pairs of solar angles. Results disprove the potential of vertical walls serving to fill the winter gap of roof mounted solar energy plants. Best wall orientation for the deployment of solar panels are west and east in summer, whereas it is southeast in winter.

  3. A numerical study of transient, thermally-conductive solar wind

    NASA Technical Reports Server (NTRS)

    Han, S. M.; Wu, S. T.; Dryer, M.

    1987-01-01

    A numerical analysis of transient solar wind starting at the solar surface and arriving at 1 AU is performed by an implicit numerical method. The model hydrodynamic equations include thermal conduction terms for both steady and unsteady simulations. Simulation results show significant influence of thermal conduction on both steady and time-dependent solar wind. Higher thermal conduction results in higher solar wind speed, higher temperature, but lower plasma density at 1 AU. Higher base temperature at the solar surface gives lower plasma speed, lower temperature, but higher density at 1 AU. Higher base density, on the other hand, gives lower velocity, lower temperature, but higher density at 1 AU.

  4. 3D self-assembly of aluminium nanoparticles for plasmon-enhanced solar desalination

    NASA Astrophysics Data System (ADS)

    Zhou, Lin; Tan, Yingling; Wang, Jingyang; Xu, Weichao; Yuan, Ye; Cai, Wenshan; Zhu, Shining; Zhu, Jia

    2016-06-01

    Plasmonics has generated tremendous excitement because of its unique capability to focus light into subwavelength volumes, beneficial for various applications such as light harvesting, photodetection, sensing, catalysis and so on. Here we demonstrate a plasmon-enhanced solar desalination device, fabricated by the self-assembly of aluminium nanoparticles into a three-dimensional porous membrane. The formed porous plasmonic absorber can float naturally on water surface, efficiently absorb a broad solar spectrum (>96%) and focus the absorbed energy at the surface of the water to enable efficient (˜90%) and effective desalination (a decrease of four orders of magnitude). The durability of the devices has also been examined, indicating a stable performance over 25 cycles under various illumination conditions. The combination of the significant desalination effect, the abundance and low cost of the materials, and the scalable production processes suggest that this type of plasmon-enhanced solar desalination device could provide a portable desalination solution.

  5. Genesis Solar Wind Science Canister Components Curated as Potential Solar Wind Collectors and Reference Contamination Sources

    NASA Technical Reports Server (NTRS)

    Allton, J. H.; Gonzalez, C. P.; Allums, K. K.

    2016-01-01

    The Genesis mission collected solar wind for 27 months at Earth-Sun L1 on both passive and active collectors carried inside of a Science Canister, which was cleaned and assembled in an ISO Class 4 cleanroom prior to launch. The primary passive collectors, 271 individual hexagons and 30 half-hexagons of semiconductor materials, are described in. Since the hard landing reduced the 301 passive collectors to many thousand smaller fragments, characterization and posting in the online catalog remains a work in progress, with about 19% of the total area characterized to date. Other passive collectors, surfaces of opportunity, have been added to the online catalog. For species needing to be concentrated for precise measurement (e.g. oxygen and nitrogen isotopes) an energy-independent parabolic ion mirror focused ions onto a 6.2 cm diameter target. The target materials, as recovered after landing, are described in. The online catalog of these solar wind collectors, a work in progress, can be found at: http://curator.jsc.nasa.gov/gencatalog/index.cfm This paper describes the next step, the cataloging of pieces of the Science Canister, which were surfaces exposed to the solar wind or component materials adjacent to solar wind collectors which may have contributed contamination.

  6. Remote-sensing Observations of the Corona and Solar Wind

    NASA Astrophysics Data System (ADS)

    Sheeley, Neil R., Jr.

    2009-05-01

    On June 25, 1908, George Ellery Hale used the 60-foot Tower Telescope on Mount Wilson to make the first measurements of magnetic fields in sunspots. This began a series of studies that led to Hale's Law of sunspot polarities and established the Mount Wilson Observatory as a leading center of solar magnetic field research. The magnetic aura was still present in 1962 when I began solar research there as a Caltech graduate student. Mount Wilson astronomer Horace Babcock and his father had invented the solar magnetograph, discovered the polar fields of the Sun, and observed their reversal near the 1958 sunspot maximum. Caltech physicist Robert Leighton had added new instrumentation to the Mount Wilson spectroheliograph and obtained high-resolution maps of the magnetic field. Babcock had just published his classic paper on the topology of the field and its 22-year cycle. The paper contained a sketch, illustrating the coronal field-line reconnection, which he thought must occur in response to changes of the photospheric field. Some loops flew away in the yet-to-be-discovered solar wind and other loops collapsed back to the Sun. In this talk, I will present new observations from the SOHO and STEREO spacecraft, which show such coronal changes. Loops stretch out in the expanding corona and tear away from the Sun like drops from a leaky faucet. Simultaneous observations with different perspectives show that the detached loops are really helices in 3-D. Off-pointed heliospheric imagers allow us to track these ejections outward past planets (including Earth) and comets, and to observe their compression into a heliospheric spiral, as a consequence of longitudinal speed gradients on the rotating Sun. And XUV observations of the solar disk show brightness changes associated with reconnections high in the corona, like auroral displays in the magnetosphere.

  7. Genesis Solar Wind Samples: Update of Availability

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. P.; Allums, K. K.; Allton, J. H.

    2015-01-01

    The Genesis mission collected solar wind atoms for 28 months with a variety of collectors. The array wafer collector availability is displayed in the online catalog. The purpose of this report is to update the community on availability of array wafer samples and to preview other collectors which are in the process of being added to the online catalog. A total of fifteen pure materials were selected based on engineering and science requirements. Most of the materials were semiconductor wafers which were mounted on the arrays.

  8. Spectroscopic measurements of solar wind generation

    NASA Technical Reports Server (NTRS)

    Kohl, J. L.; Withbroe, G. L.; Zapata, C. A.; Noci, G.

    1983-01-01

    Spectroscopically observable quantities are described which are sensitive to the primary plasma parameters of the solar wind's source region. The method is discussed in which those observable quantities are used as constraints in the construction of empirical models of various coronal structures. Simulated observations are used to examine the fractional contributions to observed spectral intensities from coronal structures of interest which co-exist with other coronal structures along simulated lines-of-sight. The sensitivity of spectroscopic observables to the physical parameters within each of those structures is discussed.

  9. 3D cloud detection and tracking system for solar forecast using multiple sky imagers

    DOE PAGES

    Peng, Zhenzhou; Yu, Dantong; Huang, Dong; ...

    2015-06-23

    We propose a system for forecasting short-term solar irradiance based on multiple total sky imagers (TSIs). The system utilizes a novel method of identifying and tracking clouds in three-dimensional space and an innovative pipeline for forecasting surface solar irradiance based on the image features of clouds. First, we develop a supervised classifier to detect clouds at the pixel level and output cloud mask. In the next step, we design intelligent algorithms to estimate the block-wise base height and motion of each cloud layer based on images from multiple TSIs. Thus, this information is then applied to stitch images together intomore » larger views, which are then used for solar forecasting. We examine the system’s ability to track clouds under various cloud conditions and investigate different irradiance forecast models at various sites. We confirm that this system can 1) robustly detect clouds and track layers, and 2) extract the significant global and local features for obtaining stable irradiance forecasts with short forecast horizons from the obtained images. Finally, we vet our forecasting system at the 32-megawatt Long Island Solar Farm (LISF). Compared with the persistent model, our system achieves at least a 26% improvement for all irradiance forecasts between one and fifteen minutes.« less

  10. 3D cloud detection and tracking system for solar forecast using multiple sky imagers

    SciTech Connect

    Peng, Zhenzhou; Yu, Dantong; Huang, Dong; Heiser, John; Yoo, Shinjae; Kalb, Paul

    2015-06-23

    We propose a system for forecasting short-term solar irradiance based on multiple total sky imagers (TSIs). The system utilizes a novel method of identifying and tracking clouds in three-dimensional space and an innovative pipeline for forecasting surface solar irradiance based on the image features of clouds. First, we develop a supervised classifier to detect clouds at the pixel level and output cloud mask. In the next step, we design intelligent algorithms to estimate the block-wise base height and motion of each cloud layer based on images from multiple TSIs. Thus, this information is then applied to stitch images together into larger views, which are then used for solar forecasting. We examine the system’s ability to track clouds under various cloud conditions and investigate different irradiance forecast models at various sites. We confirm that this system can 1) robustly detect clouds and track layers, and 2) extract the significant global and local features for obtaining stable irradiance forecasts with short forecast horizons from the obtained images. Finally, we vet our forecasting system at the 32-megawatt Long Island Solar Farm (LISF). Compared with the persistent model, our system achieves at least a 26% improvement for all irradiance forecasts between one and fifteen minutes.

  11. Testing the Effects of Expansion on Solar Wind Turbulence

    NASA Astrophysics Data System (ADS)

    Vech, Daniel; Chen, Christopher H. K.

    2016-11-01

    We present a multi-spacecraft approach to test the predictions of recent studies on the effect of solar wind expansion on the radial spectral, variance, and local 3D anisotropies of the turbulence. We found that on small scales (5000-10,000 km) the power levels of the B-trace structure functions do not depend on the sampling direction with respect to the radial suggesting that on this scale the effect of expansion is small possibly due to fast turbulent timescales. On larger scales (110-135 R E ), the fluctuations of the radial magnetic field component are reduced by ˜20% compared to the transverse (perpendicular to radial) ones, which could be due to expansion confining the fluctuations into the plane perpendicular to radial. For the local 3D spectral anisotropy, the B-trace structure functions showed dependence on the sampling direction with respect to radial. The anisotropy in the perpendicular plane is reduced when the increments are taken perpendicular with respect to radial, which could be an effect of expansion.

  12. Latitudinal Dependence of Coronal Hole-Associated Fast Solar Wind

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Landi, E.

    2014-05-01

    The fast solar wind can have at least two different coronal sources: high-latitude, polar coronal holes (PCH) and low-latitude, equatorial coronal holes (ECH). The in-situ differences in the PCH and ECH winds have not been well studied, nor have the differences in their evolution over the solar cycles. Ulysses' 19 years of observations from 1990 to 2009, combined with ACE observations from 1998 to the present, provide us with measurements of solar wind properties that span two entire solar cycles, which allow us to study the in-situ properties and evolution of the coronal hole-associated solar wind at different latitudes. In this work, we focus on the PCH and ECH solar winds during the minima between solar cycles 22-23 and 23-24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses, and SWICS, SWEPAM, and MAG on board ACE to analyze the proton dynamics, heavy ion composition, elemental abundance, and magnetic field properties of the PCH wind and ECH wind, with a special focus on their differences during the recent two solar minima. We also include the slow and hot, streamer-associated (ST) wind as a reference in the comparison. The comparison of PCH and ECH wind shows that: 1) the in-situ properties of ECH and PCH winds are significantly different during the two solar minima, and 2) the two types of coronal hole-associated solar wind respond differently to changes in solar activity strength from cycle 23 to cycle 24.

  13. Coronal streamers in the solar wind at 1 AU

    NASA Technical Reports Server (NTRS)

    Gosling, J. T.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Borrini, G.; Hansen, R. T.

    1981-01-01

    Virtually all solar wind observing groups have reported substantial variations in the solar wind helium-hydrogen abundance ratio (A(He)). A study of Los Alamos Imp solar wind data has revealed an association between low A(He) and high proton density that occurs at low flow speeds and that is correlated with polarity reversals of the interplanetary magnetic field. The current investigation has the objective to present further examples of the low A(He), high proton density, low speed, magnetic field polarity association, and to document the common occurrence of multiple events lasting approximately 3-7 days. The results are presented of attempts to relate these events directly to maps or isophotes of solar coronal brightness at 1.5 solar radii. The results of the investigation suggest that a substantial fraction of the low-speed solar wind originates in coronal streamers, particularly near solar minimum.

  14. Solar Wind Spectrometer on Lunar Surface

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Sitting on the lunar surface, this Solar Wind Spectrometer is measuring the energies of the particles that make up the solar wind. This was one of the instruments used during the Apollo 12 mission. The second manned lunar landing mission, Apollo 12 launched from launch pad 39-A at Kennedy Space Center in Florida on November 14, 1969 via a Saturn V launch vehicle. The Saturn V vehicle was developed by the Marshall Space Flight Center (MSFC) under the direction of Dr. Wernher von Braun. Aboard Apollo 12 was a crew of three astronauts: Alan L. Bean, pilot of the Lunar Module (LM), Intrepid; Richard Gordon, pilot of the Command Module (CM), Yankee Clipper; and Spacecraft Commander Charles Conrad. The LM, Intrepid, landed astronauts Conrad and Bean on the lunar surface in what's known as the Ocean of Storms while astronaut Richard Gordon piloted the CM, Yankee Clipper, in a parking orbit around the Moon. Lunar soil activities included the deployment of the Apollo Lunar Surface Experiments Package (ALSEP), finding the unmanned Surveyor 3 that landed on the Moon on April 19, 1967, and collecting 75 pounds (34 kilograms) of rock samples. Apollo 12 safely returned to Earth on November 24, 1969.

  15. Anisotropy in solar wind plasma turbulence

    PubMed Central

    Oughton, S.; Matthaeus, W. H.; Wan, M.; Osman, K. T.

    2015-01-01

    A review of spectral anisotropy and variance anisotropy for solar wind fluctuations is given, with the discussion covering inertial range and dissipation range scales. For the inertial range, theory, simulations and observations are more or less in accord, in that fluctuation energy is found to be primarily in modes with quasi-perpendicular wavevectors (relative to a suitably defined mean magnetic field), and also that most of the fluctuation energy is in the vector components transverse to the mean field. Energy transfer in the parallel direction and the energy levels in the parallel components are both relatively weak. In the dissipation range, observations indicate that variance anisotropy tends to decrease towards isotropic levels as the electron gyroradius is approached; spectral anisotropy results are mixed. Evidence for and against wave interpretations and turbulence interpretations of these features will be discussed. We also present new simulation results concerning evolution of variance anisotropy for different classes of initial conditions, each with typical background solar wind parameters. PMID:25848082

  16. 3D magnetic field configuration of small-scale reconnection events in the solar plasma atmosphere

    NASA Astrophysics Data System (ADS)

    Shimizu, T.

    2015-10-01

    The outer solar atmosphere, i.e., the corona and the chromosphere, is replete with small energy-release events, which are accompanied by transient brightening and jet-like ejections. These events are considered to be magnetic reconnection events in the solar plasma, and their dynamics have been studied using recent advanced observations from the Hinode spacecraft and other observatories in space and on the ground. These events occur at different locations in the solar atmosphere and vary in their morphology and amount of the released energy. The magnetic field configurations of these reconnection events are inferred based on observations of magnetic fields at the photospheric level. Observations suggest that these magnetic configurations can be classified into two groups. In the first group, two anti-parallel magnetic fields reconnect to each other, yielding a 2D emerging flux configuration. In the second group, helical or twisted magnetic flux tubes are parallel or at a relative angle to each other. Reconnection can occur only between anti-parallel components of the magnetic flux tubes and may be referred to as component reconnection. The latter configuration type may be more important for the larger class of small-scale reconnection events. The two types of magnetic configurations can be compared to counter-helicity and co-helicity configurations, respectively, in laboratory plasma collision experiments.

  17. 3D magnetic field configuration of small-scale reconnection events in the solar plasma atmosphere

    SciTech Connect

    Shimizu, T.

    2015-10-15

    The outer solar atmosphere, i.e., the corona and the chromosphere, is replete with small energy-release events, which are accompanied by transient brightening and jet-like ejections. These events are considered to be magnetic reconnection events in the solar plasma, and their dynamics have been studied using recent advanced observations from the Hinode spacecraft and other observatories in space and on the ground. These events occur at different locations in the solar atmosphere and vary in their morphology and amount of the released energy. The magnetic field configurations of these reconnection events are inferred based on observations of magnetic fields at the photospheric level. Observations suggest that these magnetic configurations can be classified into two groups. In the first group, two anti-parallel magnetic fields reconnect to each other, yielding a 2D emerging flux configuration. In the second group, helical or twisted magnetic flux tubes are parallel or at a relative angle to each other. Reconnection can occur only between anti-parallel components of the magnetic flux tubes and may be referred to as component reconnection. The latter configuration type may be more important for the larger class of small-scale reconnection events. The two types of magnetic configurations can be compared to counter-helicity and co-helicity configurations, respectively, in laboratory plasma collision experiments.

  18. The solar wind effect on cosmic rays and solar activity

    NASA Technical Reports Server (NTRS)

    Fujimoto, K.; Kojima, H.; Murakami, K.

    1985-01-01

    The relation of cosmic ray intensity to solar wind velocity is investigated, using neutron monitor data from Kiel and Deep River. The analysis shows that the regression coefficient of the average intensity for a time interval to the corresponding average velocity is negative and that the absolute effect increases monotonously with the interval of averaging, tau, that is, from -0.5% per 100km/s for tau = 1 day to -1.1% per 100km/s for tau = 27 days. For tau 27 days the coefficient becomes almost constant independently of the value of tau. The analysis also shows that this tau-dependence of the regression coefficiently is varying with the solar activity.

  19. The very slow solar wind in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Sanchez-Diaz, E.; Segura, K.; Rouillard, A.; Lavraud, B.; Tao, C.; Blelly, P. L.

    2015-12-01

    Measurements near 1AU of the bulk and compositional properties of the interplanetary plasma point to the existence of two solar winds that can be classified by their speeds, V, the fast (V>400 km s-1) and slow winds (V<400 km s-1). The slow solar wind is seldom observed slower than 300 km s-1 at 1 AU. We show that, closer to the Sun, there is a big amount of solar wind slower than 300 km s-1, hereafter very slow solar wind (VSSW). It is mostly detected inside 0.7 AU by the HELIOS spacecraft during solar maximum (1979-1980). The closer to the Sun the slower it can be observed, reaching velocities of 200 kms-1 near 0.3 AU. This very slow wind usually contains the very dense heliospheric plasma sheet as well as the heliospheric current sheet. The very low speeds disappear by 1AU likely due to the interaction with the faster plasma. Solar Probe Plus will measure in-situ how low in the inner Heliosphere this interaction starts and whether even lower velocities are observed inside 0.3 AU. The VSSW has higher density and lower temperature than regular slow solar wind, qualitatively extending the known scaling laws for the solar wind over 300 km s-1(Lopez & Freeman, 1986) (Hundhausen, Bame, Asbridge, & Sydoriak, 1970). Like the rest of the slow solar wind, the helium abundance of the VSSW increase with solar activity, approaching to the fast wind composition at solar maximum. Combining a Potential Field Source Surface (PFSS) to a ballistic backmapping, we relate the ins-situ measurements to the solar surface. We compute the proton density flux just above the photosphere and find much higher fluxes in the VSSW than in the faster winds at solar maximum. Based on this, we propose a likely mechanism for the solar cycle variability of the helium abundance of the VSSW and slow solar wind, which will be tested by combining Solar Orbiter and Solar Probe Plus measurements of the VSSW with high resolution and high cadence Carrington maps. This work was funded by the EU FP7 HELCATS

  20. Western Wind and Solar Integration Study Phase 3: Technical Overview

    SciTech Connect

    2015-11-01

    Technical fact sheet outlining the key findings of Phase 3 of the Western Wind and Solar Integration Study (WWSIS-3). NREL and GE find that with good system planning, sound engineering practices, and commercially available technologies, the Western grid can maintain reliability and stability during the crucial first minute after grid disturbances with high penetrations of wind and solar power.

  1. Solar and Wind Technologies for Hydrogen Production Report to Congress

    SciTech Connect

    None, None

    2005-12-01

    DOE's Solar and Wind Technologies for Hydrogen Production Report to Congress summarizes the technology roadmaps for solar- and wind-based hydrogen production. Published in December 2005, it fulfills the requirement under section 812 of the Energy Policy Act of 2005.

  2. A two-fluid model of the solar wind

    NASA Technical Reports Server (NTRS)

    Sandbaek, O.; Leer, E.; Holzer, T. E.

    1992-01-01

    A method is presented for the integration of the two-fluid solar-wind equations which is applicable to a wide variety of coronal base densities and temperatures. The method involves proton heat conduction, and may be applied to coronal base conditions for which subsonic-supersonic solar wind solutions exist.

  3. Correlations between solar wind parameters and auroral kilometric radiation intensity

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.; Dangelo, N.

    1981-01-01

    The relationship between solar wind properties and the influx of energy into the nightside auroral region as indicated by the intensity of auroral kilometric radiation is investigated. Smoothed Hawkeye satellite observations of auroral radiation at 178, 100 and 56.2 kHz for days 160 through 365 of 1974 are compared with solar wind data from the composite Solar Wind Plasma Data Set, most of which was supplied by the IMP-8 spacecraft. Correlations are made between smoothed daily averages of solar wind ion density, bulk flow speed, total IMF strength, electric field, solar wind speed in the southward direction, solar wind speed multiplied by total IMF strength, the substorm parameter epsilon and the Kp index. The greatest correlation is found between solar wind bulk flow speed and auroral radiation intensity, with a linear correlation coefficient of 0.78 for the 203 daily averages examined. A possible mechanism for the relationship may be related to the propagation into the nightside magnetosphere of low-frequency long-wavelength electrostatic waves produced in the magnetosheath by the solar wind.

  4. Time dependence of Fe/O ratio within a 3D solar energetic particle propagation model including drift

    NASA Astrophysics Data System (ADS)

    Dalla, S.; Marsh, M. S.; Zelina, P.; Laitinen, T.

    2017-02-01

    Context. The intensity profiles of iron and oxygen in Solar Energetic Particle (SEP) events often display differences that result in a decreasing Fe/O ratio over time. The physical mechanisms behind this behaviour are not fully understood, but these observational signatures provide important tests of physical modelling efforts. Aims: In this paper we study the propagation of iron and oxygen SEP ions using a 3D model of propagation which includes the effect of guiding centre drift in a Parker spiral magnetic field. We derive time intensity profiles for a variety of observer locations and study the temporal evolution of the Fe/O ratio. Methods: We use a 3D full orbit test particle model which includes scattering. The configuration of the interplanetary magnetic field is a unipolar Parker spiral. Particles are released instantaneously from a compact region at two solar radii and allowed to propagate in 3D. Results: Both Fe and O experience significant transport across the magnetic field due to gradient and curvature drifts. We find that Fe ions drift more than O ions due to their larger mass-to-charge ratio, so that an observer that is not magnetically well connected to the source region will observe Fe arriving before O, for particles within the same range in energy per nucleon. As a result, for the majority of observer locations, the Fe/O ratio displays a decrease in time. Conclusions: We conclude that propagation effects associated with drifts produce a decay over time of the Fe/O ratio, qualitatively reproducing that observed in SEP event profiles.

  5. Turbulence in the solar wind: Kinetic effects

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.

    1995-01-01

    Although a casual look at the fluctuating magnetic and velocity fields in the solar wind may be reminiscent of a chaotic and disordered flow, there is, nonetheless. considerable organization and structure in the temporal and spatial evolution of those fluctuations. Much of that evolution is controlled by processes operating on rather large scales for example, in the inner heliosphere, the fluctuations in magnetic and velocity are highly correlated in the sense of outward propagating Alfven waves. This correlation can be destroyed both in time and distance by the velocity gradients present between fast and slow streams and by other nonlinear processes which stir the medium, producing a turbulent cascade of energy from large to small scales. Many aspects of this turbulent evolution can be described using fluid models; however, at some scale the fluid approximation breaks down and a more detailed paradigm is necessary. The breakdown is evident in the power spectrum of magnetic fluctuations at scales approaching the wavelength of ion cyclotron waves. At those scales, as evident in Mariner 10 and other magnetometer data, the spectrum bends over and the fluctuations damp, possibly heating the ambient plasma. Some evidence for heating of the solar wind is present in the Voyager data. Fluid models can be modified to some extent to incorporate aspects of a kinetic treatment. This is done by modifying the dissipation terms in the fluid equations and by including extra terms, such as the Hall term. As the scale lengths of phenomena shrink further and approach the spatial and temporal scales characteristic of electron phenomena, the fluid description must be abandoned altogether and a fully kinetic treatment is required. One example is the generation of Langmuir solitons produced by the electron beams that generate type 3 solar radio bursts.

  6. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells.

    PubMed

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, JunHo; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-07-07

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.

  7. INTERPRETING MAGNETIC VARIANCE ANISOTROPY MEASUREMENTS IN THE SOLAR WIND

    SciTech Connect

    TenBarge, J. M.; Klein, K. G.; Howes, G. G.; Podesta, J. J.

    2012-07-10

    The magnetic variance anisotropy (A{sub m}) of the solar wind has been used widely as a method to identify the nature of solar wind turbulent fluctuations; however, a thorough discussion of the meaning and interpretation of the A{sub m} has not appeared in the literature. This paper explores the implications and limitations of using the A{sub m} as a method for constraining the solar wind fluctuation mode composition and presents a more informative method for interpreting spacecraft data. The paper also compares predictions of the A{sub m} from linear theory to nonlinear turbulence simulations and solar wind measurements. In both cases, linear theory compares well and suggests that the solar wind for the interval studied is dominantly Alfvenic in the inertial and dissipation ranges to scales of k{rho}{sub i} {approx_equal} 5.

  8. Solar wind control of auroral zone geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Clauer, C. R.; Mcpherron, R. L.; Searls, C.; Kivelson, M. G.

    1981-01-01

    Solar wind magnetosphere energy coupling functions are analyzed using linear prediction filtering with 2.5 minute data. The relationship of auroral zone geomagnetic activity to solar wind power input functions are examined, and a least squares prediction filter, or impulse response function is designed from the data. Computed impulse response functions are observed to have characteristics of a low pass filter with time delay. The AL index is found well related to solar wind energy functions, although the AU index shows a poor relationship. High frequency variations of auroral indices and substorm expansions are not predictable with solar wind information alone, suggesting influence by internal magnetospheric processes. Finally, the epsilon parameter shows a poorer relationship with auroral geomagnetic activity than a power parameter, having a VBs solar wind dependency.

  9. The Western Wind and Solar Integration Study Phase 2

    SciTech Connect

    Lew, D.; Brinkman, G.; Ibanez, E.; Hodge, B. M.; Hummon, M.; Florita, A.; Heaney, M.

    2013-09-01

    The electric grid is a highly complex, interconnected machine, and changing one part of the grid can have consequences elsewhere. Adding wind and solar affects the operation of the other power plants and adding high penetrations can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 of the Western Wind and Solar Integration Study (WWSIS-2) evaluated these costs and emissions and simulated grid operations for a year to investigate the detailed impact of wind and solar on the fossil-fueled fleet. This built on Phase 1, one of the largest wind and solar integration studies ever conducted, which examined operational impacts of high wind and solar penetrations in the West.

  10. The Western Wind and Solar Integration Study Phase 2

    SciTech Connect

    Lew, Debra; Brinkman, Greg; Ibanez, E.; Florita, A.; Heaney, M.; Hodge, B. -M.; Hummon, M.; Stark, G.; King, J.; Lefton, S. A.; Kumar, N.; Agan, D.; Jordan, G.; Venkataraman, S.

    2013-09-01

    The electric grid is a highly complex, interconnected machine, and changing one part of the grid can have consequences elsewhere. Adding wind and solar affects the operation of the other power plants and adding high penetrations can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 of the Western Wind and Solar Integration Study (WWSIS-2) evaluated these costs and emissions and simulated grid operations for a year to investigate the detailed impact of wind and solar on the fossil-fueled fleet. This built on Phase 1, one of the largest wind and solar integration studies ever conducted, which examined operational impacts of high wind and solar penetrations in the West(GE Energy 2010).

  11. On Determination of 3D Morphology and Plasma Properties of the Solar Corona

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; Davis, John M.; Moore, Ronald; Six, N. Frank (Technical Monitor)

    2002-01-01

    An earlier analysis preformed and published will be revisited and applied to SECCHI's observations. Using coronal models and imaging-rendering techniques we will investigate several important facts regarding the solar stereographic mission. A synthesized image will be presented formed from integrating the emission from the volume elements along the line-of-sight path through a three-dimensional volume. We used analysis of pairs of these synthesized images with various angular perspectives to investigate the effect of angular separation on mission objectives. The resulting images and analysis provide guidelines for developing a stereographic mission analysis program.

  12. Solar Wind Composition: First Results from SOHO and Future Expectations

    NASA Astrophysics Data System (ADS)

    Galvin, A. B.; Ipavich, F. M.; Gloeckler, G.; Coplan, M.; Hovestadt, D.; Hilchenbach, M.; Buergi, A.; Klecker, B.; Scholer, M.; Bochsler, P.; Balsiger, H.; Geiss, J.; Kallenbach, R.; Wurz, P.; Gruenwaldt, H.; Axford, W. I.; Livi, S.; Marsch, E.; Wilken, B.; Gliem, F.; Reiche, K.-U.; Lee, M. A.; Moebius, E.; Hsieh, K. C.; Neugebauer, M.; Managadze, G. G.; Verigin, M. I.

    1996-05-01

    The SOHO payload includes three experiments designed to make "in situ" particle measurements of the solar wind and solar energetic particles (CELIAS, D. Hovestadt PI; COSTEP, H. Kunow PI; ERNE, J. Torsti PI). The solar wind measurements that are the focus of this talk are primarily provided by the CELIAS CTOF and MTOF sensors. (CELIAS/STOF and COSTEP-ERNE measure solar and interplanetary suprathermal and energetic particle populations.) CELIAS/CTOF measures solar wind heavy ion elemental and charge state abundances, information which is used (for example) in identifying the type of solar wind flow and the ionization processes in the corona where the solar wind charge states become "frozen-in". CELIAS/MTOF provides heavy ion elemental and isotopic abundances that are important (for example) in the study of fractionation factors in coronal abundances (as in the so-called "FIP-effect") for the rarer elements not resolvable in conventional solar wind composition instruments, and in determining the isotopic make-up of the solar corona. MTOF is, by far, the most powerful solar wind mass spectrometer flown to date, and already has new science to report at the time of this writing. This happenstance is due to a combination of (1) advanced technology in obtaining high mass resolution for ions at solar wind energies, and (2) increased statistics. The excellent counting statistics are largely due to continuous solar wind monitoring (with its position at L1, ``the Sun never sets on SOHO''), and the continuous sampling of the solar wind by the 3-axis stabilized spacecraft further enhanced by MTOF's novel, never previously flown deflection system that encompasses a very large dynamic range. As might be expected, this unique opportunity has allowed MTOF to identify a number of elements for the first time in the solar wind (e.g., P, Ti, Cr and Ni). A rich assortment of solar wind isotopes have been identified for the first time, many of which (e.g., Fe 54 and 56; Ni 58,60,62) have

  13. Short-scale variations of the solar wind helium abundance

    SciTech Connect

    Šafránková, J.; Němeček, Z.; Cagaš, P.; Přech, L.; Pavlů, J.; Zastenker, G. N.; Riazantseva, M. O.; Koloskova, I. V.

    2013-11-20

    Abrupt changes of the relative He abundance in the solar wind are usually attributed to encounters with boundaries dividing solar wind streams from different sources in the solar corona. This paper presents a systematic study of fast variations of the He abundance that supports the idea that a majority of these variations on short timescales (3-30 s) are generated by in-transit turbulence that is probably driven by the speed difference between the ion species. This turbulence contributes to the solar wind heating and leads to a correlation of the temperature with He abundance.

  14. Solar-wind tritium limit and nuclear processes in the solar atmosphere

    NASA Technical Reports Server (NTRS)

    Fireman, E. L.; Damico, J.; Defelice, J.

    1975-01-01

    Tritium in Surveyor 3 material is measured, and the resulting H-3/H-1 ratio for the solar wind is applied in a solar flare-solar wind relation to investigate the mixing requirements for the solar atmosphere. The flare-wind relation is derived. None of the tritium can be attributed to solar-wind implantation. The upper limit for the H-3/He ratio in the solar wind is 4 times 10 to the minus tenth power and corresponds to a H-3/H-1 limit of 2 times 10 to the minus eleventh power. This limit imposes a requirement on the mixing rate in the solar atmosphere if the H-3 production rate in solar-surface nuclear reactions is greater than 160/sq cm per sec.

  15. Feasibility study of a solar-and-wind-powered desalinization device (SOWIDE). Final report

    SciTech Connect

    Garstang, M.; David, D.C.; Snow, J.W.

    1980-06-01

    The scope, need and feasibility of a solar-wind desalinization (SOWIDE) system is examined. A climatological study shows the scope and need where a water deficit, a saline source and solar and wind power coincide. Representative stations around the globe serve as examples. When climatological data are used, relatively few locations meet all requirements. Optimization of wind and solar energy through careful site selection would, however, greatly extend the use of an alternate energy powered desalinization system such as SOWIDE. The technical feasibility of SOWIDE is described in terms of the conceptual design which uses solar energy to heat impounded water, saturating a volume of air above the impoundment at the temperature of the water. The water vapor is extracted by condensation through a wind powered refrigerator. Latent heat is returned to the impoundment by the refrigerator fluid with additional heat provided by a pre-heater using heat from the brine discharge and by a resistance heater or stirrer driven by the wind generator. The important considerations of the design include the joint use of solar and wind power, optimization of the heat balance and the fact that the system operates at a low temperature which inhibits scaling and efficiency losses. Results show that the system will deliver 1 m/sup 3/ d/sup -1/ of fresh water at operating temperatures of 42 to 70/sup 0/C. At an operating temperature of 60/sup 0/C, the total power required is about 8 kW, equally partitioned between the solar and wind inputs. The operating temperatures and power requirements suggest that the SOWIDE system is technically feasible. Application of the system must await the testing of a prototype and an economic study.

  16. Feasibility study of a solar and wind powered desalinization device (SOWIDE). Final report

    SciTech Connect

    Garstang, M.; David, D.C.; Snow, J.W.

    1980-06-01

    The scope, need and feasibility of a solar-wind desalinization (SOWIDE) system is examined. A climatological study shows the scope and need where a water deficit, a saline source and solar and wind power coincide. Representative stations around the globe serve as examples. When climatological data are used, relatively few locations meet all requirements. Optimization of wind and solar energy through careful site selection would, however, greatly extend the use of an alternate energy powered desalinization system such as SOWIDE. The technical feasibility of SOWIDE is described in terms of the conceptual design which uses solar energy to heat impounded water, saturating a volume of air above the impoundment at the temperature of the water. The water vapor is extracted by condensation through a wind powered refrigerator. Latent heat is returned to the impoundment by the refrigerator fluid with additional heat provided by a pre-heater using heat from the brine discharge and by a resistance heater or stirrer driven by the wind generator. The important considerations of the design include the joint use of solar and wind power, optimization of the heat balance and the fact that the system operates at a low temperature which inhibits scaling and efficiency losses. Results show that the system will deliver 1 m/sup 3/ d/sup -1/ of fresh water at operating temperatures of 42 to 70/sup 0/C. At an operating temperature of 60/sup 0/C, the total power required is about 8 kW, equally partitioned between the solar and wind inputs. The operating temperatures and power requirements suggest that the SOWIDE system is technically feasible. Application of the system must await the testing of a prototype and an economic study.

  17. MERIDIONAL CIRCULATION DYNAMICS FROM 3D MAGNETOHYDRODYNAMIC GLOBAL SIMULATIONS OF SOLAR CONVECTION

    SciTech Connect

    Passos, Dário; Charbonneau, Paul; Miesch, Mark

    2015-02-10

    The form of solar meridional circulation is a very important ingredient for mean field flux transport dynamo models. However, a shroud of mystery still surrounds this large-scale flow, given that its measurement using current helioseismic techniques is challenging. In this work, we use results from three-dimensional global simulations of solar convection to infer the dynamical behavior of the established meridional circulation. We make a direct comparison between the meridional circulation that arises in these simulations and the latest observations. Based on our results, we argue that there should be an equatorward flow at the base of the convection zone at mid-latitudes, below the current maximum depth helioseismic measures can probe (0.75 R{sub ⊙}). We also provide physical arguments to justify this behavior. The simulations indicate that the meridional circulation undergoes substantial changes in morphology as the magnetic cycle unfolds. We close by discussing the importance of these dynamical changes for current methods of observation which involve long averaging periods of helioseismic data. Also noteworthy is the fact that these topological changes indicate a rich interaction between magnetic fields and plasma flows, which challenges the ubiquitous kinematic approach used in the vast majority of mean field dynamo simulations.

  18. Solar Prominences Embedded in Flux Ropes: Morphological Features and Dynamics from 3D MHD Simulations

    NASA Astrophysics Data System (ADS)

    Terradas, J.; Soler, R.; Luna, M.; Oliver, R.; Ballester, J. L.; Wright, A. N.

    2016-04-01

    The temporal evolution of a solar prominence inserted in a three-dimensional magnetic flux rope is investigated numerically. Using the model of Titov & Démoulin under the regime of weak twist, the cold and dense prominence counteracts gravity by modifying the initially force-free magnetic configuration. In some cases a quasi-stationary situation is achieved after the relaxation phase, characterized by the excitation of standing vertical oscillations. These oscillations show a strong attenuation with time produced by the mechanism of continuum damping due to the inhomogeneous transition between the prominence and solar corona. The characteristic period of the vertical oscillations does not depend strongly on the twist of the flux rope. Nonlinearity is responsible for triggering the Kelvin-Helmholtz instability associated with the vertical oscillations and that eventually produces horizontal structures. Contrary to other configurations in which the longitudinal axis of the prominence is permeated by a perpendicular magnetic field, like in unsheared arcades, the orientation of the prominence along the flux rope axis prevents the development of Rayleigh-Taylor instabilities and therefore the appearance of vertical structuring along this axis.

  19. SOLAR PROMINENCES EMBEDDED IN FLUX ROPES: MORPHOLOGICAL FEATURES AND DYNAMICS FROM 3D MHD SIMULATIONS

    SciTech Connect

    Terradas, J.; Soler, R.; Oliver, R.; Ballester, J. L.; Luna, M.; Wright, A. N.

    2016-04-01

    The temporal evolution of a solar prominence inserted in a three-dimensional magnetic flux rope is investigated numerically. Using the model of Titov and Démoulin under the regime of weak twist, the cold and dense prominence counteracts gravity by modifying the initially force-free magnetic configuration. In some cases a quasi-stationary situation is achieved after the relaxation phase, characterized by the excitation of standing vertical oscillations. These oscillations show a strong attenuation with time produced by the mechanism of continuum damping due to the inhomogeneous transition between the prominence and solar corona. The characteristic period of the vertical oscillations does not depend strongly on the twist of the flux rope. Nonlinearity is responsible for triggering the Kelvin–Helmholtz instability associated with the vertical oscillations and that eventually produces horizontal structures. Contrary to other configurations in which the longitudinal axis of the prominence is permeated by a perpendicular magnetic field, like in unsheared arcades, the orientation of the prominence along the flux rope axis prevents the development of Rayleigh–Taylor instabilities and therefore the appearance of vertical structuring along this axis.

  20. Geomagnetic responses to the solar wind and the solar activity

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1975-01-01

    Following some historical notes, the formation of the magnetosphere and the magnetospheric tail is discussed. The importance of electric fields is stressed and the magnetospheric convection of plasma and magnetic field lines under the influence of large-scale magnetospheric electric fields is outlined. Ionospheric electric fields and currents are intimately related to electric fields and currents in the magnetosphere and the strong coupling between the two regions is discussed. The energy input of the solar wind to the magnetosphere and upper atmosphere is discussed in terms of the reconnection model where interplanetary magnetic field lines merge or connect with the terrestrial field on the sunward side of the magnetosphere. The merged field lines are then stretched behind earth to form the magnetotail so that kinetic energy from the solar wind is converted into magnetic energy in the field lines in the tail. Localized collapses of the crosstail current, which is driven by the large-scale dawn/dusk electric field in the magnetosphere, divert part of this current along geomagnetic field lines to the ionosphere, causing substorms with auroral activity and magnetic disturbances. The collapses also inject plasma into the radiation belts and build up a ring current. Frequent collapses in rapid succession constitute the geomagnetic storm.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. MORPHOLOGY AND DYNAMICS OF SOLAR PROMINENCES FROM 3D MHD SIMULATIONS

    SciTech Connect

    Terradas, J.; Soler, R.; Oliver, R.; Ballester, J. L.; Luna, M.

    2015-01-20

    In this paper we present a numerical study of the time evolution of solar prominences embedded in sheared magnetic arcades. The prominence is represented by a density enhancement in a background-stratified atmosphere and is connected to the photosphere through the magnetic field. By solving the ideal magnetohydrodynamic equations in three dimensions, we study the dynamics for a range of parameters representative of real prominences. Depending on the parameters considered, we find prominences that are suspended above the photosphere, i.e., detached prominences, but also configurations resembling curtain or hedgerow prominences whose material continuously connects to the photosphere. The plasma-β is an important parameter that determines the shape of the structure. In many cases magnetic Rayleigh-Taylor instabilities and oscillatory phenomena develop. Fingers and plumes are generated, affecting the whole prominence body and producing vertical structures in an essentially horizontal magnetic field. However, magnetic shear is able to reduce or even to suppress this instability.

  3. Corrigendum to "Measuring the 3-D wind vector with a weight-shiftmicrolight aircraft" published in Atmos. Meas. Tech., 4, 1421-1444, 2011

    NASA Astrophysics Data System (ADS)

    Metzger, S.; Junkermann, W.; Butterbach-Bahl, K.; Schmid, H. P.; Foken, T.

    2011-07-01

    This study investigates whether the 3-D wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the wind measurement: (a) A wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s-1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical wind component does not exceed 0.3 m s-1. (c) The comparison with ground based wind measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s-1 for the horizontal and ≈0.3 m s-1 for the vertical wind components. No conclusive dependence of the uncertainty on the wind magnitude (<8 m s-1) or true airspeed (ranging from 23-30 m s-1) is found. Hence our analysis provides the necessary basis to study the wind measurement precision and spectral quality, which is prerequisite for reliable Eddy-Covariance flux measurements.

  4. Implications of L1 observations for slow solar wind formation by solar reconnection

    NASA Astrophysics Data System (ADS)

    Kepko, L.; Viall, N. M.; Antiochos, S. K.; Lepri, S. T.; Kasper, J. C.; Weberg, M.

    2016-05-01

    While the source of the fast solar wind is known to be coronal holes, the source of the slow solar wind has remained a mystery. Long time scale trends in the composition and charge states show strong correlations between solar wind velocity and plasma parameters, yet these correlations have proved ineffective in determining the slow wind source. We take advantage of new high time resolution (12 min) measurements of solar wind composition and charge state abundances at L1 and previously identified 90 min quasiperiodic structures to probe the fundamental timescales of slow wind variability. The combination of new high temporal resolution composition measurements and the clearly identified boundaries of the periodic structures allows us to utilize these distinct solar wind parcels as tracers of slow wind origin and acceleration. We find that each 90 min (2000 Mm) parcel of slow wind has near-constant speed yet exhibits repeatable, systematic charge state and composition variations that span the entire range of statistically determined slow solar wind values. The classic composition-velocity correlations do not hold on short, approximately hourlong, time scales. Furthermore, the data demonstrate that these structures were created by magnetic reconnection. Our results impose severe new constraints on slow solar wind origin and provide new, compelling evidence that the slow wind results from the sporadic release of closed field plasma via magnetic reconnection at the boundary between open and closed flux in the Sun's atmosphere.

  5. Stationarity of extreme bursts in the solar wind

    NASA Astrophysics Data System (ADS)

    Moloney, N. R.; Davidsen, J.

    2014-05-01

    Recent results have suggested that the statistics of bursts in the solar wind vary with solar cycle. Here, we show that this variation is basically absent if one considers extreme bursts. These are defined as threshold-exceeding events over the range of high thresholds for which their number decays as a power law. In particular, we find that the distribution of duration times and energies of extreme bursts in the solar wind ɛ parameter and similar observables are independent of the solar cycle and in this sense stationary, and show robust asymptotic power laws with exponents that are independent of the specific threshold. This is consistent with what has been observed for solar flares and, thus, provides evidence in favor of a link between solar flares and extreme bursts in the solar wind.

  6. Stationarity of extreme bursts in the solar wind.

    PubMed

    Moloney, N R; Davidsen, J

    2014-05-01

    Recent results have suggested that the statistics of bursts in the solar wind vary with solar cycle. Here, we show that this variation is basically absent if one considers extreme bursts. These are defined as threshold-exceeding events over the range of high thresholds for which their number decays as a power law. In particular, we find that the distribution of duration times and energies of extreme bursts in the solar wind ε parameter and similar observables are independent of the solar cycle and in this sense stationary, and show robust asymptotic power laws with exponents that are independent of the specific threshold. This is consistent with what has been observed for solar flares and, thus, provides evidence in favor of a link between solar flares and extreme bursts in the solar wind.

  7. Solar energetic particle events in different types of solar wind

    SciTech Connect

    Kahler, S. W.; Vourlidas, A.

    2014-08-10

    We examine statistically some properties of 96 20 MeV gradual solar energetic proton (SEP) events as a function of three different types of solar wind (SW) as classified by Richardson and Cane. Gradual SEP (E > 10 MeV) events are produced in shocks driven by fast (V ≳ 900 km s{sup –1}) and wide (W > 60°) coronal mass ejections (CMEs). We find no differences among the transient, fast, and slow SW streams for SEP 20 MeV proton event timescales. It has recently been found that the peak intensities Ip of these SEP events scale with the ∼2 MeV proton background intensities, which may be a proxy for the near-Sun shock seed particles. Both the intensities Ip and their 2 MeV backgrounds are significantly enhanced in transient SW compared to those of fast and slow SW streams, and the values of Ip normalized to the 2 MeV backgrounds only weakly correlate with CME V for all SW types. This result implies that forecasts of SEP events could be improved by monitoring both the Sun and the local SW stream properties and that the well known power-law size distributions of Ip may differ between transient and long-lived SW streams. We interpret an observed correlation between CME V and the 2 MeV background for SEP events in transient SW as a manifestation of enhanced solar activity.

  8. Solar Coronal Plumes and the Fast Solar Wind

    NASA Astrophysics Data System (ADS)

    Dwivedi, Bhola N.; Wilhelm, Klaus

    2015-03-01

    The spectral profiles of the coronal Ne viii line at 77 nm have different shapes in quiet-Sun regions and Coronal Holes (CHs). A single Gaussian fit of the line profile provides an adequate approximation in quiet-Sun areas, whereas, a strong shoulder on the long-wavelength side is a systematic feature in CHs. Although this has been noticed since 1999, no physical reason for the peculiar shape could be given. In an attempt to identify the cause of this peculiarity, we address three problems that could not be conclusively resolved, in a review article by a study team of the International Space Science Institute (ISSI) (Wilhelm et al. 2011): (1) The physical processes operating at the base and inside of plumes, as well as their interaction with the Solar Wind (SW). (2) The possible contribution of plume plasma to the fast SW streams. (3) The signature of the First-Ionization Potential (FIP) effect between plumes and inter-plume regions (IPRs). Before the spectroscopic peculiarities in IPRs and plumes in Polar Coronal Holes (PCHs) can be further investigated with the instrument Solar Ultraviolet Measurements of Emitted Radiation (SUMER) aboard the Solar and Heliospheric Observatory (SOHO), it is mandatory to summarize the results of the review to place the spectroscopic observations into context. Finally, a plume model is proposed that satisfactorily explains the plasma flows up and down the plume field lines and leads to the shape of the neon line in PCHs.

  9. Innovations in Wind and Solar PV Financing

    SciTech Connect

    Cory, K.; Coughlin, J.; Jenkin, T.; Pater, J.; Swezey, B.

    2008-02-01

    There is growing national interest in renewable energy development based on the economic, environmental, and security benefits that these resources provide. Historically, greater development of our domestic renewable energy resources has faced a number of hurdles, primarily related to cost, regulation, and financing. With the recent sustained increase in the costs and associated volatility of fossil fuels, the economics of renewable energy technologies have become increasingly attractive to investors, both large and small. As a result, new entrants are investing in renewable energy and new business models are emerging. This study surveys some of the current issues related to wind and solar photovoltaic (PV) energy project financing in the electric power industry, and identifies both barriers to and opportunities for increased investment.

  10. Genesis Solar Wind Array Collector Cataloging Status

    NASA Technical Reports Server (NTRS)

    Burkett, P.J.; Rodriguez, M.C.; Calaway, M.C.; Allton, J.H.

    2009-01-01

    Genesis solar wind array collectors were fractured upon landing hard in Utah in 2004. The fragments were retrieved from the damaged canister, imaged, repackaged and shipped to the Johnson Space Center curatorial facility [1]. As of January 2009, the collection consists of 3460 samples. Of these, 442 are comprised into "multiple" sample groupings, either affixed to adhesive paper (177) or collected in jars (17), culture trays (87), or sets of polystyrene vials (161). A focused characterization task was initiated in May 2008 to document the largest samples in the collection. The task consisted of two goals: to document sapphire based fragments greater than 2 cm in one dimension, and to document silicon based fragments greater than 1 cm in one direction.

  11. Nonaxisymmetric anisotropy of solar wind turbulence.

    PubMed

    Turner, A J; Gogoberidze, G; Chapman, S C; Hnat, B; Müller, W-C

    2011-08-26

    A key prediction of turbulence theories is frame-invariance, and in magnetohydrodynamic (MHD) turbulence, axisymmetry of fluctuations with respect to the background magnetic field. Paradoxically the power in fluctuations in the turbulent solar wind are observed to be ordered with respect to the bulk macroscopic flow as well as the background magnetic field. Here, nonaxisymmetry across the inertial and dissipation ranges is quantified using in situ observations from Cluster. The observed inertial range nonaxisymmetry is reproduced by a "fly through" sampling of a direct numerical simulation of MHD turbulence. Furthermore, fly through sampling of a linear superposition of transverse waves with axisymmetric fluctuations generates the trend in nonaxisymmetry with power spectral exponent. The observed nonaxisymmetric anisotropy may thus simply arise as a sampling effect related to Taylor's hypothesis and is not related to the plasma dynamics itself.

  12. ASYMMETRIC ELECTRON DISTRIBUTIONS IN THE SOLAR WIND

    SciTech Connect

    Rha, Kicheol; Ryu, Chang-Mo; Yoon, Peter H.

    2013-09-20

    A plausible mechanism responsible for producing asymmetric electron velocity distribution functions in the solar wind is investigated by means of one-dimensional electrostatic particle-in-cell (PIC) simulation. A recent paper suggests that the variation in the ion-to-electron temperature ratio influences the nonlinear wave-particle dynamics such that it results in the formation of asymmetric distributions. The present PIC code simulation largely confirms this finding, but quantitative differences between the weak turbulence formalism and the present PIC simulation are also found, suggesting the limitation of the analytical method. The inter-relationship between the asymmetric electron distribution and the ion-to-electron temperature ratio may be a new useful concept for the observation.

  13. Evolution of solar wind turbulence and intermittency over the solar cycle

    NASA Astrophysics Data System (ADS)

    Väisänen, Pauli; Virtanen, Ilpo; Echim, Marius; Munteanu, Costel; Mursula, Kalevi

    2016-04-01

    Solar wind is a natural, near-by plasma physics laboratory, which offers possibilities to study plasma physical phenomena over a wide range of parameter values that are difficult to reach in ground-based laboratories. Accordingly, the solar wind is subject of many studies of, e.g., intermittency, turbulence and other nonlinear space plasma phenomena. Turbulence is an important feature of the solar wind dynamics, e.g., for the energy transfer mechanisms and their scale invariance, the solar wind evolution, the structure of the heliospheric magnetic field (HMF), the particle energization and heating, and for phenomena related to solar wind interaction with the planetary plasma systems. Here we analyse high resolution measurements of the solar wind and the heliospheric magnetic field provided by several ESA and NASA satellites, including ACE, STEREO, Ulysses and Cluster. This collection of satellites allows us to compile and study nearly 20 years of high-resolution solar wind and HMF measurements from the start of solar cycle 23 to the current declining phase of solar cycle 24. Long-term studies require homogeneity and, therefore, we pay great attention to the reliability and consistency of the data, in particular to instrumental defects like spin harmonics, the purity of the solar wind and its possible contamination in the foreshock by magnetospheric ions. We study how the different key-descriptors of turbulence like the slope of the power law of power spectral density and the kurtosis of the fluctuations of the heliospheric magnetic field vary over the solar cycle.

  14. Solar semidiurnal tidal wind oscillations above the CART site

    NASA Astrophysics Data System (ADS)

    Whiteman, C. D.; Bian, X.

    1995-03-01

    Harmonic analysis of wintertime data from 915- and 404-MHz radar wind profilers at four sites in North America has identified coherent semidiurnal wind oscillations through the entire depth of the troposphere. These winds are readily apparent above the CART site, as evidenced from analyses of data from the Haviland, KS, radar profiler. The characteristics of this wind system match the characteristics of solar semidiurnal atmospheric tides, as predicted by a simple dynamic model.

  15. Three decades of 3D global simulations of the solar dynamo (Invited)

    NASA Astrophysics Data System (ADS)

    Glatzmaier, G. A.

    2009-12-01

    Studies of convective dynamos using dynamically consistent three-dimensional numerical simulations began with the work of Gilman and Miller (1981). Their Boussinesq simulations maintained a differential rotation "constant on cylinders" and produced magnetic cycles, but with fields propagating toward the poles, unlike the sunspot cycle. Anelastic dynamo simulations then illustrated the effects of the large radial gradients in density, temperature and diffusivity (Glatzmaier 1984) and could generate fields in the overshoot region at the base of the convection zone that propagate toward the equator. However, the differential rotation was still mainly "constant on cylinders" throughout most of the convection zone. Helioseismology then showed that the sun's internal rotation profile is closer to "constant on radii", especially at mid-latitude. As computers became more powerful and parallel, more turbulent (i.e., realistic) simulations were produced (Toomre et al.), which demonstrated the importance of resolving more of the turbulent flux of angular momentum in maintaining differential rotation and generating magnetic field. Considerable progress has been made over the past three decades; but we are still far from having a clear understanding of the magnetohydrodynamics of the solar convection zone, tachocline and internal radiative region.

  16. RESIDUAL ENERGY SPECTRUM OF SOLAR WIND TURBULENCE

    SciTech Connect

    Chen, C. H. K.; Bale, S. D.; Salem, C. S.; Maruca, B. A.

    2013-06-20

    It has long been known that the energy in velocity and magnetic field fluctuations in the solar wind is not in equipartition. In this paper, we present an analysis of 5 yr of Wind data at 1 AU to investigate the reason for this. The residual energy (difference between energy in velocity and magnetic field fluctuations) was calculated using both the standard magnetohydrodynamic (MHD) normalization for the magnetic field and a kinetic version, which includes temperature anisotropies and drifts between particle species. It was found that with the kinetic normalization, the fluctuations are closer to equipartition, with a mean normalized residual energy of {sigma}{sub r} = -0.19 and mean Alfven ratio of r{sub A} = 0.71. The spectrum of residual energy, in the kinetic normalization, was found to be steeper than both the velocity and magnetic field spectra, consistent with some recent MHD turbulence predictions and numerical simulations, having a spectral index close to -1.9. The local properties of residual energy and cross helicity were also investigated, showing that globally balanced intervals with small residual energy contain local patches of larger imbalance and larger residual energy at all scales, as expected for nonlinear turbulent interactions.

  17. The Paleoarchean geodynamo, solar wind and magnetopause

    NASA Astrophysics Data System (ADS)

    Tarduno, John A.; Cottrell, R. D.; Watkeys, M. K.; Hofmann, A.; Doubrovine, P. V.; Mamajek, E.; Liu, D.; Sibeck, D. G.; Neukirch, L. P.; Usui, Y.

    2010-05-01

    The standoff of stellar winds by a planetary magnetic field prevents atmospheric erosion and water loss important for the evolution of a habitable planet. But little is known about early magnetic field strength and whether intense radiation from the young, rapidly rotating Sun modified Earth's atmosphere. New paleointensity results from single silicate crystals bearing magnetic inclusions indicate the presence of a geodynamo between 3.4 and 3.45 billion years ago. The field measured is ~30-50% weaker than that of present-day and when combined with a greater solar wind pressure suggests steady-state Paleoarchean magnetopause standoff distances ≤ 5 Earth radii, similar to values observed during recent coronal mass ejection events. Aurora would have been at lower latitudes and polar cap area is predicted to have been up to 3 times greater than today. Heating, expansion and volatile loss from the exosphere is implied, affecting long-term atmospheric composition. Efforts to examine even older Paleoarchean-Hadean magnetic mineral carriers for geomagnetic paleointensity signatures will be discussed.

  18. Flux tubes embedded into reconnection outflows in the solar wind

    NASA Astrophysics Data System (ADS)

    Voros, Z.; Zaqarashvili, T.; Sasunov, Y.; Narita, Y.

    2015-12-01

    Reconnection exhausts in the solar wind are usually interpreted in terms of a quasi-stationary Petschek-type reconnection model. Accordingly, within a region of magnetic field reversal, the wedge-shaped, Alfvenic accelerated plasma outflow is bounded by layers containing (anti-) correlated components of speed and magnetic field fluctuations. However, time-dependent impulsive reconnection can generate flux ropes embedded into accelerated outflows. Reconnection associated moving flux ropes or plasmoids are frequently observed in the Earth's magnetotail, while similar observations are missing in the solar wind. We present the first observations of small-scale magnetic flux ropes associated with reconnection exhausts in the solar wind, using the data from the WIND probe. We argue that the interaction of moving flux ropes with the background plasma can generate turbulence leading finally to the local heating of the solar wind.

  19. Active region plasma outflows as sources of slow/intermediate solar wind

    NASA Astrophysics Data System (ADS)

    van Driel-Gesztelyi, Lidia M.

    2015-08-01

    L. van Driel-Gesztelyi (1,2,3), D. Baker (1), P. Démoulin (2), Culhane, J.L. (1), M.L. DeRosa (4) C.H. Mandrini (5,6), D.H. Brooks (7), A.N. Fazakerley (1), L.K. Harra (1), L. Zhao (7), T.H. Zurbuchen (7), F.A. Nuevo (5,6), A.M. Vásquez (5,6), G.D. Cristiani (5,6) M. Pick (2)1) UCL/MSSL, UK, (2) Paris Observatory, LESIA, CNRS, France, (3) Konkoly Observatory, Hungary, (4) Lockheed Martin Solar and Astrophysics Laboratory, USA, (5) IAFE, CONICET-UBA, Argentina (6) FCEN, UBA, Argentina (7) Dept. of Atmospheric, Oceanic and Earth Sciences, Univ. of Michigan, USAWe analyse plasma upflows of tens of km/s from the edges of solar active regions discovered by Hinode/EIS and investigate whether or not they become outflows, i.e. find their way into the solar wind. We analyse two magnetic configurations: bipolar and quadrupolar and find that the active region plasma may be directly channeled into the solar wind via interchange reconnection at a high-altitude null point above the active region especially when active regions are located besides coronal holes or in a more complex way via multiple reconnections even from under a closed helmet streamer. We relate the solar observations to in-situ slow/intermediate solar wind streams.

  20. MODELING STATISTICAL PROPERTIES OF SOLAR ACTIVE REGIONS THROUGH DIRECT NUMERICAL SIMULATIONS OF 3D-MHD TURBULENCE

    SciTech Connect

    Malapaka, Shiva Kumar; Mueller, Wolf-Christian

    2013-09-01

    Statistical properties of the Sun's photospheric turbulent magnetic field, especially those of the active regions (ARs), have been studied using the line-of-sight data from magnetograms taken by the Solar and Heliospheric Observatory and several other instruments. This includes structure functions and their exponents, flatness curves, and correlation functions. In these works, the dependence of structure function exponents ({zeta}{sub p}) of the order of the structure functions (p) was modeled using a non-intermittent K41 model. It is now well known that the ARs are highly turbulent and are associated with strong intermittent events. In this paper, we compare some of the observations from Abramenko et al. with the log-Poisson model used for modeling intermittent MHD turbulent flows. Next, we analyze the structure function data obtained from the direct numerical simulations (DNS) of homogeneous, incompressible 3D-MHD turbulence in three cases: sustained by forcing, freely decaying, and a flow initially driven and later allowed to decay (case 3). The respective DNS replicate the properties seen in the plots of {zeta}{sub p} against p of ARs. We also reproduce the trends and changes observed in intermittency in flatness and correlation functions of ARs. It is suggested from this analysis that an AR in the onset phase of a flare can be treated as a forced 3D-MHD turbulent system in its simplest form and that the flaring stage is representative of decaying 3D-MHD turbulence. It is also inferred that significant changes in intermittency from the initial onset phase of a flare to its final peak flaring phase are related to the time taken by the system to reach the initial onset phase.

  1. Non-magnetic photospheric bright points in 3D simulations of the solar atmosphere

    NASA Astrophysics Data System (ADS)

    Calvo, F.; Steiner, O.; Freytag, B.

    2016-11-01

    Context. Small-scale bright features in the photosphere of the Sun, such as faculae or G-band bright points, appear in connection with small-scale magnetic flux concentrations. Aims: Here we report on a new class of photospheric bright points that are free of magnetic fields. So far, these are visible in numerical simulations only. We explore conditions required for their observational detection. Methods: Numerical radiation (magneto-)hydrodynamic simulations of the near-surface layers of the Sun were carried out. The magnetic field-free simulations show tiny bright points, reminiscent of magnetic bright points, only smaller. A simple toy model for these non-magnetic bright points (nMBPs) was established that serves as a base for the development of an algorithm for their automatic detection. Basic physical properties of 357 detected nMBPs were extracted and statistically evaluated. We produced synthetic intensity maps that mimic observations with various solar telescopes to obtain hints on their detectability. Results: The nMBPs of the simulations show a mean bolometric intensity contrast with respect to their intergranular surroundings of approximately 20%, a size of 60-80 km, and the isosurface of optical depth unity is at their location depressed by 80-100 km. They are caused by swirling downdrafts that provide, by means of the centripetal force, the necessary pressure gradient for the formation of a funnel of reduced mass density that reaches from the subsurface layers into the photosphere. Similar, frequently occurring funnels that do not reach into the photosphere, do not produce bright points. Conclusions: Non-magnetic bright points are the observable manifestation of vertically extending vortices (vortex tubes) in the photosphere. The resolving power of 4-m-class telescopes, such as the DKIST, is needed for an unambiguous detection of them. The movie associated to Fig. 1 is available at http://www.aanda.org

  2. Global MHD modeling of an ICME focused on the physics involved in an ICME interacting with a solar wind

    NASA Astrophysics Data System (ADS)

    An, Jun-Mo; Magara, Tetsuya; Inoue, Satoshi; Hayashi, Keiji; Tanaka, Takashi

    2015-04-01

    We developed a three-dimensional (3D) magnetohydrodynamic (MHD) code to investigate the structure of a solar wind, the properties of a coronal mass ejection (CME) and the interaction between them. This MHD code is based on the finite volume method incorporating total variation diminishing (TVD) scheme with an unstructured grid system. In particular, this grid system can avoid the singularity at the north and south poles and relax tight CFL conditions around the poles, both of which would arise in a spherical coordinate system (Tanaka 1994). In this model, we first apply an MHD tomographic method (Hayashi et al. 2003) to interplanetary scintillation (IPS) observational data and derive a solar wind from the physical values obtained at 50 solar radii away from the Sun. By comparing the properties of this solar wind to observational data obtained near the Earth orbit, we confirmed that our model captures the velocity, temperature and density profiles of a solar wind near the Earth orbit. We then insert a spheromak-type CME (Kataoka et al. 2009) into the solar wind to reproduce an actual CME event occurred on 29 September 2013. This has been done by introducing a time-dependent boundary condition to the inner boundary of our simulation domain (50rs < r < 300rs). On the basis of a comparison between the properties of a simulated CME and observations near the Earth, we discuss the physics involved in an ICME interacting with a solar wind.

  3. Evidence for solar wind control of Saturn radio emission

    NASA Technical Reports Server (NTRS)

    Desch, M. D.

    1982-01-01

    Using data collected by the Voyager 1 and 2 spacecraft in 1980 and 1981, strong evidence is presented for a direct correlation between variations in the solar wind at Saturn and the level of activity of Saturn's nonthermal radio emission. Correlation coefficients of 57 to 58% are reached at lag times of 0 to 1 days between the arrival at Saturn of high pressure solar wind streams and the onset of increased radio emission. The radio emission exhibits a long-term periodicity of 25 days, identical to the periodicity seen in the solar wind at this time and consistent with the solar rotation period. The energy coupling efficiency between the solar wind with the Saturn radio emission is estimated and compared with that for Earth.

  4. Modeling solar wind with boundary conditions from interplanetary scintillations

    DOE PAGES

    Manoharan, P.; Kim, T.; Pogorelov, N. V.; ...

    2015-09-30

    Interplanetary scintillations make it possible to create three-dimensional, time- dependent distributions of the solar wind velocity. Combined with the magnetic field observations in the solar photosphere, they help perform solar wind simulations in a genuinely time-dependent way. Interplanetary scintillation measurements from the Ooty Radio Astronomical Observatory in India provide directions to multiple stars and may assure better resolution of transient processes in the solar wind. In this paper, we present velocity distributions derived from Ooty observations and compare them with those obtained with the Wang-Sheeley-Arge (WSA) model. We also present our simulations of the solar wind flow from 0.1 AUmore » to 1 AU with the boundary conditions based on both Ooty and WSA data.« less

  5. Modeling solar wind with boundary conditions from interplanetary scintillations

    SciTech Connect

    Manoharan, P.; Kim, T.; Pogorelov, N. V.; Arge, C. N.

    2015-09-30

    Interplanetary scintillations make it possible to create three-dimensional, time- dependent distributions of the solar wind velocity. Combined with the magnetic field observations in the solar photosphere, they help perform solar wind simulations in a genuinely time-dependent way. Interplanetary scintillation measurements from the Ooty Radio Astronomical Observatory in India provide directions to multiple stars and may assure better resolution of transient processes in the solar wind. In this paper, we present velocity distributions derived from Ooty observations and compare them with those obtained with the Wang-Sheeley-Arge (WSA) model. We also present our simulations of the solar wind flow from 0.1 AU to 1 AU with the boundary conditions based on both Ooty and WSA data.

  6. Little or no solar wind enters Venus' atmosphere at solar minimum.

    PubMed

    Zhang, T L; Delva, M; Baumjohann, W; Auster, H-U; Carr, C; Russell, C T; Barabash, S; Balikhin, M; Kudela, K; Berghofer, G; Biernat, H K; Lammer, H; Lichtenegger, H; Magnes, W; Nakamura, R; Schwingenschuh, K; Volwerk, M; Vörös, Z; Zambelli, W; Fornacon, K-H; Glassmeier, K-H; Richter, I; Balogh, A; Schwarzl, H; Pope, S A; Shi, J K; Wang, C; Motschmann, U; Lebreton, J-P

    2007-11-29

    Venus has no significant internal magnetic field, which allows the solar wind to interact directly with its atmosphere. A field is induced in this interaction, which partially shields the atmosphere, but we have no knowledge of how effective that shield is at solar minimum. (Our current knowledge of the solar wind interaction with Venus is derived from measurements at solar maximum.) The bow shock is close to the planet, meaning that it is possible that some solar wind could be absorbed by the atmosphere and contribute to the evolution of the atmosphere. Here we report magnetic field measurements from the Venus Express spacecraft in the plasma environment surrounding Venus. The bow shock under low solar activity conditions seems to be in the position that would be expected from a complete deflection by a magnetized ionosphere. Therefore little solar wind enters the Venus ionosphere even at solar minimum.

  7. Iron charge states in the solar wind as measured by SMS on Wind

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Cohen, C. M. S.; Ipavich, F. M.; Gloeckler, G.; Hamilton, D. C.; Chotoo, K.; Balsiger, H.; Sheldon, R.

    1995-01-01

    The Wind spacecraft was launched in November 1994. In the first half of 1995 it was in the interplanetary medium upstream of the Earth. The Solar Wind and Suprathermal Ion Composition Experiment (SMS) on Wind consists of three sensors, the Solar Wind Ion Composition Spectrometer (SWICS), the Suprathermal Ion Composition Spectrometer (STICS), and the high mass resolution spectrometer (MASS). All three instruments utilize electrostatic deflection combined with time-of-flight measurement. The data from these three sensors allows the determination of the ionic composition of the solar wind in a variety of solar wind conditions over a large energy/charge range (0.5 to 230 keV/e). We have examined the Wind database for time periods conducive to observing solar wind iron. With the high mass resolution of the MASS spectrometer (M/Delta-M greater than 100) iron is easily identified while the electrostatic deflection provides information concerning the mass/charge distribution. We present here the relative abundance of iron charge states in the solar wind near 1 AU.

  8. MEASUREMENTS OF RAPID DENSITY FLUCTUATIONS IN THE SOLAR WIND

    SciTech Connect

    Malaspina, D. M.; Ergun, R. E.; Kellogg, P. J.; Bale, S. D.

    2010-03-01

    The power spectrum of density fluctuations in the solar wind is inferred by tracking small timescale changes in the electron plasma frequency during periods of strong Langmuir wave activity. STEREO electric field waveform data are used to produce time profiles of plasma density from which the density power spectrum is derived. The power spectra obtained by this method extend the observed frequency range by an order of magnitude while remaining consistent with previous results near a few Hertz. Density power spectral indices are found to be organized by the angle between the local magnetic field and the solar wind direction, indicating significant anisotropy in solar wind high-frequency density turbulence.

  9. Mars: A Richly Complicated Obstacle to the Solar Wind

    NASA Astrophysics Data System (ADS)

    Crider, Dana H.; Brain, David A.; Lundin, Rickard

    2008-06-01

    Chapman Conference on the Solar Wind Interaction With Mars; San Diego, California, 22-25 January 2008; Although studies of the solar wind interaction with Mars (SWIM) date back to the mid-1960s, whether Mars possessed a global magnetic field remained uncertain until 1997. We now know that Mars lacks a measurable dynamo; however, it has intense, localized regions of magnetization tied to its crust. With this patchy magnetic field, the solar wind interacts directly with the upper atmosphere of Mars, driving structural and compositional variations and providing energy for atmospheric escape to space. These processes may have played an important role in the long-term evolution of the Martian climate.

  10. The relationship between Saturn kilometric radiation and the solar wind

    NASA Technical Reports Server (NTRS)

    Desch, M. D.; Rucker, H. O.

    1983-01-01

    Voyager spacecraft radio, interplanetary plasma, and interplanetary magnetic field data are used to show that large amplitude fluctuations in the power generated by the Saturn kilometric radio emission are best correlated with solar wind ram pressure variation. In all, thirteen solar wind quantities previously found important in driving terrestrial magnetospheric substorms and other auroral processes were examined for evidence of correlations with the Saturn radio emission. The results are consistent with hydromagnetic wave or eddy diffusion processes driven by large scale solar wind pressure changes at Saturn's dayside magnetopause.

  11. Multifractal properties of solar wind turbulence: theory and observations.

    NASA Astrophysics Data System (ADS)

    Milovanov, A. V.; Avanov, L. A.; Zastenker, G. N.; Zelenyj, L. M.

    1996-10-01

    A fractal model of the solar wind is presented. This model treats fluctuations of the solar wind velocity from the viewpoint of nonlinear processes originating in the convective region and photosphere of the Sun. The multifractal structure of proton velocity fluctuations in a region of heliocentric distances from 0.2 to 0.8 AU is a result of these processes. Continuous measurements of solar wind velocity aboard the ISEE-3 spacecraft during one month were used to compare the theoretical and experimental results. It is shown that fluctuations of proton velocity have a multifractal structure in a frequency range of 10-5 - 10-3Hz.

  12. The solar wind interaction with unmagnetized planets - A tutorial

    NASA Technical Reports Server (NTRS)

    Luhmann, J. G.

    1990-01-01

    The interaction of the solar wind with the Venus ionosphere induces currents which can substantially exclude the solar wind and IMF from the dayside ionosphere beneath the 'ionopause', where ionosphere thermal pressure equals incident solar wind dynamic pressure. The field then diffuses through the ionopause with increasing speed at decreasing altitudes, and is weakest in the subpolar region. Once within the ionopause, the magnetic field is redistributed by ionospheric convection, and then decays at low altitudes via collisional dissipation of the associated currents. The maximum ionospheric field magnitudes observed, of about 150 nT, furnish magnetic pressures exceeding the ionospheric thermal pressure by a factor of about 3.

  13. Solar wind control of Jupiter's hectometric radio emission

    NASA Technical Reports Server (NTRS)

    Barrow, C. H.; Desch, M. D.

    1989-01-01

    Radio, plasma, and magnetic field data obtained by Voyager 1 and Voyager 2 were used to examine the manner in which the Jovian hectometric radio emission (HOM) is controlled by the solar wind. Using the method of superposed epochs, it was found that the higher energy HOM is correlated with the IMF as well as with the solar wind density and pressure. However, unlike the Io-independent decametric radio emission (Non-Io DAM), the HOM displayed no correlation with the solar wind velocity, although this radio component appear to be also influenced by the IMF. The results suggest separate HOM amd Non-Io DAM sources.

  14. Solar wind, radiation belt electrons and atmospheric vorticity

    NASA Astrophysics Data System (ADS)

    Mironova, Irina; Tinsley, Brian; Zhou, Limin

    The association of atmospheric vorticity changes with solar wind sector structure explored by John Wilcox and Walter Orr Roberts in the 1970s is examined in terms of the sector related minima in solar wind speed, and associated minima in relativistic electron precipitation from the outer radiation belt. Stronger correlations of atmospheric vorticity with the relativistic electron flux are found than with either solar wind speed or the passage of magnetic sector boundaries over the Earth. This is consistent with changes in the ionosphere-earth current density affecting cloud microphysics, with the ionization from the Bremsstrahlung X-rays from the relativistic electron precipitation increasing the conductivity of the stratosphere.

  15. A three-dimensional model of corotating streams in the solar wind. 1: Theoretical foundations

    NASA Technical Reports Server (NTRS)

    Pizzo, V. J.

    1978-01-01

    The theoretical and mathematical background pertinent to the study of steady, corotating solar wind structure in all three spatial dimensions (3-D) is discussed. The dynamical evolution of the plasma in interplanetary space (defined as the region beyond roughly 35 solar radii where the flow is supersonic) is approximately described by the nonlinear, single fluid, polytropic (magneto-) hydrodynamic equations. Efficient numerical techniques for solving this complex system of coupled, hyperbolic partial differential equations are outlined. The formulation is inviscid and nonmagnetic, but methods allow for the potential inclusion of both features with only modest modifications. One simple, highly idealized, hydrodynamic model stream is examined to illustrate the fundamental processes involved in the 3-D dynamics of stream evolution. Spatial variations in the rotational stream interaction mechanism were found to produce small nonradial flows on a global scale that lead to the transport of mass, energy, and momentum away from regions of relative compression and into regions of relative rarefaction.

  16. Systematic measurements of ion-proton differential streaming in the solar wind.

    PubMed

    Berger, L; Wimmer-Schweingruber, R F; Gloeckler, G

    2011-04-15

    The small amount of heavy ions in the highly rarefied solar wind are sensitive tracers for plasma-physics processes, which are usually not accessible in the laboratory. We have analyzed differential streaming between heavy ions and protons in the solar wind at 1 AU. 3D velocity vector and magnetic field measurements from the Solar Wind Electron Proton Alpha Monitor and the Magnetometer aboard the Advanced Composition Explorer were used to reconstruct the ion-proton difference vector v(ip) = v(i) - v(p) from the 12 min 1D Solar Wind Ion Composition Spectrometer observations. We find that all 44 analyzed heavy ions flow along the interplanetary magnetic field at velocities which are smaller than, but comparable to, the local Alfvén speed C(A). The flow speeds of 35 of the 44 ion species lie within the range of ±0.15C(A) around 0.55C(A), the flow speed of He(2+).

  17. Systematic Measurements of Ion-Proton Differential Streaming in the Solar Wind

    SciTech Connect

    Berger, L.; Wimmer-Schweingruber, R. F.; Gloeckler, G.

    2011-04-15

    The small amount of heavy ions in the highly rarefied solar wind are sensitive tracers for plasma-physics processes, which are usually not accessible in the laboratory. We have analyzed differential streaming between heavy ions and protons in the solar wind at 1 AU. 3D velocity vector and magnetic field measurements from the Solar Wind Electron Proton Alpha Monitor and the Magnetometer aboard the Advanced Composition Explorer were used to reconstruct the ion-proton difference vector v{sub ip}=v{sub i}-v{sub p} from the 12 min 1D Solar Wind Ion Composition Spectrometer observations. We find that all 44 analyzed heavy ions flow along the interplanetary magnetic field at velocities which are smaller than, but comparable to, the local Alfven speed C{sub A}. The flow speeds of 35 of the 44 ion species lie within the range of {+-}0.15C{sub A} around 0.55C{sub A}, the flow speed of He{sup 2+}.

  18. Hybrid modeling of time-dependent solar wind-comet interactions

    NASA Astrophysics Data System (ADS)

    Alho, Markku; Wedlund, Cyril Simon; Kallio, Esa; Nilsson, Hans

    2016-04-01

    Global hybrid plasma modelling of cometary environments is an essential tool in understanding the global implications of point measurements performed by the Rosetta probe in the vicinity of 67P/Churyumov-Gerasimenko. A 3-D, global hybrid plasma model, including the effects of plasma-driven ionization of cometary neutrals, has been employed to model an approximation of 67P's environment around perihelion conditions. Model inputs include solar wind upstream parameters, a simple cometary neutral model and a H2O+-bound photochemistry. In this work we present results on the responses of a cometary plasma environment when impinged upon by a time-dependent solar wind. Stepwise upward and downward density changes as well as linear ramps are investigated, along with tangential discontinuities in the interplanetary magnetic field. As the production rates of cometary ions are coupled to solar wind parameters through e.g. charge exchange and electron impact ionization, solar wind variations create non-trivial transient phenomena in the cometary environment. Implications for CME impacts and tail disconnection events are explored, giving insight on how these events may appear in the observational datasets (magnetometer, ion spectrometer) from past missions and from Rosetta.

  19. Ionospheric mid-latitude response to solar wind discontinuities

    NASA Astrophysics Data System (ADS)

    Munteanu, Costel; Mosna, Zbysek; Kouba, Daniel; Echim, Marius

    2013-04-01

    We have compiled a database of 356 discontinuities detected by both the Advanced Composition Explorer ACE) and Cluster satellites in the solar wind between 2001-2012 and analyzed their ionospheric response. Each discontinuity of the data base is defined by a change of at least 5 nT in less than 5 min in one or more components of the interplanetary magnetic field (IMF). The discontinuities are observed in January-April every year, when Cluster enters the solar wind. The ionospheric effects of solar wind discontinuities are investigated by checking the variations of critical frequencies foF2, the heights of the F layer and the ionospheric plasma dynamics recorded using ground measurement with a time resolution of 15 minutes from mid-latitude digisondes located in Czech Republic. The time delay between solar wind input and the ionospheric response is analyzed using the characteristics and the shape of the ionograms. The geoeffectiveness of the solar wind discontinuities is expressed as correlation between key plasma parameters (e,g, the solar wind velocity, magnetic jump across the discontinuity) and the ionospheric variations. Solar cycle effects are also discussed.

  20. He abundance variations in the solar wind: Observations from Ulysses

    SciTech Connect

    Barraclough, B.L.; Gosling, J.T.; Phillips, J.L.; McComas, D.J.; Feldman, W.C.; Goldstein, B.E.

    1995-09-01

    The Ulysses mission is providing the first opportunity to observe variations in solar wind plasma parameters at heliographic latitudes far removed from the ecliptic plane. We present an overview of the solar wind speed and the variability in helium abundance, [He] data on [He] in six high latitude coronal mass ejections (CMEs), and a superposed epoch analysis of [He] variations at the seven heliospheric current sheet (HCS) crossings made during the rapid-latitude-scan portion of the mission. The differences in the variability of the solar wind speed and [He] in high latitude and equatorial regions are quite striking. Solar wind speed is generally low but highly variable near the solar equator, while at higher latitudes the average speed is quite high with little variability. [He] can vary over nearly two decades at low solar latitudes, while at high latitudes it varies only slightly. In contrast to the high [He] that is commonly associated with CMEs observed in the ecliptic, none of the six high-speed CMEs encountered at high southern heliographic latitudes showed any significant variation in helium content. A superposed epoch analysis of the [He] during all seven HCS crossings made as Ulysses passed from the southern to northern solar hemisphere shows the expected [He] minimum near the crossing and a broad region of low [He] around the crossing time. We discuss how our solar wind [He] observations may provide an accurate measure of the helium composition for the entire convective zone of the Sun.

  1. Solar wind-plasma interaction: The AMPTE solar wind plasma releases

    NASA Technical Reports Server (NTRS)

    1986-01-01

    In situ measurements during AMPTE solar wind ion releases are described. The creation of a diamagnetic cavity, compression and draping of magnetic field lines, recoil of the entire artificial comet, and ion beam and tail formation are discussed. The wave measurements were used to determine the time variation of the plasma density from the measurement of the electron plasma frequency and to determine the state of cloud expansion and cavity formation. Features found include absence of strong turbulence and anomalous diffusion in the cavity boundary, and the appearance of very intense shock-like emission in front of the plasma clouds. The first effect suggests partially unknowm processes leading to magnetic field penetration into the region of the clouds. The direct observation of the interaction processes between the fast streaming solar wind plasma and the expanding cloud plasma of the Li and artificial comet releases may have relevance to astrophysical situations as, for instance, encountered in solar flares, interstellar clouds, or during accretion of matter onto compact objects.

  2. Suprathermal Ion Acceleration in Multiple Contracting and Reconnecting Inertial-scale Flux Ropes in the Supersonic Solar Wind.

    NASA Astrophysics Data System (ADS)

    le Roux, J. A.; Zank, G. P.; Webb, G. M.

    2014-12-01

    3D and 2D MHD turbulence simulations with a strong large-scale magnetic field show that the turbulence is filled with quasi-2D inertial-scale flux ropes that intermittently reconnect, while test particle simulations stress how suprathermal particles can be efficiently accelerated to produce power law spectra (kappa distributions) when traversing multiple flux ropes. Solar wind observations indicate that the statistical properties of the turbulence agree well with the MHD turbulence simulation. In addition, recent observations show the presence of different size inertial-scale magnetic islands in the slow solar wind near the heliospheric current sheet, evidence of island merging, and of heating of ions and electrons in their vicinity. At the same time, observations in the supersonic solar wind suggest the existence of suprathermal ion spectra in the solar wind frame where the distribution function is a power law in momentum with a -5 exponent. We present a new statistical transport theory to model the acceleration of superthermal ions traversing multiple contracting and reconnecting inertial-scale quasi-2D flux ropes in the supersonic solar wind. Steady-state analytical solutions for the accelerated suprathermal particle spectrum in a radially expanding solar wind will be explored to show under what conditions one can reproduce the observed superthermal power-law slope.

  3. Western Wind and Solar Integration Study Phase 2 (Fact Sheet)

    SciTech Connect

    Not Available

    2013-09-01

    This is one-page, two-sided fact sheet presents high-level summary results of the Western Wind and Solar Integration Study Phase 2, which examined operational impacts of high penetrations of variable renewable generation in the West.

  4. Genesis Solar Wind Sample Curation: A Progress Report

    NASA Technical Reports Server (NTRS)

    Allton, Judith H.; Calaway, M. J.; Rodriquez, M. C.; Hittle, J. D.; Wentworth, S. J.; Stansbery, E. K.; McNamara, K. M.

    2006-01-01

    In the year since the Genesis solar wind collector fragments were returned, early science samples, specimens for cleaning experiments, and science allocations have been distributed. Solar wind samples are stored under nitrogen and handled in an ISO Class 4 (Class 10) laboratory. For array collector fragments, a basic characterization process has been established. This characterization consists of identification of solar wind regime, whole fragment image for identification and surface quality, higher magnification images for contaminant particle density, and assessment of molecular film contaminant thickness via ellipsometry modeling. Compilations of this characterization data for AuOS (gold film on sapphire), and sapphire from the bulk solar wind for fragments greater than 2 cm are available. Removal of contaminant particles using flowing ultrapure water (UPW) energized megasonically is provided as requested.

  5. Origins of the Slow and the Ubiquitous Fast Solar Wind

    NASA Technical Reports Server (NTRS)

    Korendyke, Noci C.; Habbal, S. R.

    1997-01-01

    We present in this letter the first coordinated radio occultation measurements and ultraviolet observations of the inner corona below 5.5 Rs, obtained during the Galileo solar conjunction in January 1997, to establish the origin of the slow wind.

  6. Quantitative evaluation of solar wind time-shifting methods

    NASA Astrophysics Data System (ADS)

    Cameron, Taylor; Jackel, Brian

    2016-11-01

    Nine years of solar wind dynamic pressure and geosynchronous magnetic field data are used for a large-scale statistical comparison of uncertainties associated with several different algorithms for propagating solar wind measurements. The MVAB-0 scheme is best overall, performing on average a minute more accurately than a flat time-shift. We also evaluate the accuracy of these time-shifting methods as a function of solar wind magnetic field orientation. We find that all time-shifting algorithms perform significantly worse (>5 min) due to geometric effects when the solar wind magnetic field is radial (parallel or antiparallel to the Earth-Sun line). Finally, we present an empirical scheme that performs almost as well as MVAB-0 on average and slightly better than MVAB-0 for intervals with nonradial B.

  7. Integrating Multiple Approaches to Solving Solar Wind Turbulence Problems (Invited)

    NASA Astrophysics Data System (ADS)

    Karimabadi, H.; Roytershteyn, V.

    2013-12-01

    The ultimate understanding of the solar wind turbulence must explain the physical process and their connection at all scales ranging from the largest down to electron kinetic scales. This is a daunting task and as a result a more piecemeal approach to the problem has been followed. For example, the role of each wave has been explored in isolation and in simulations with scales limited to those of the underlying waves. In this talk, we present several issues with this approach and offer an alternative with an eye towards more realistic simulations of solar wind turbulence. The main simulation techniques used have been MHD, Hall MHD, hybrid, fully kinetic, and gyrokinetic. We examine the limitations of each approach and their viability for studies of solar wind turbulence. Finally, the effect of initial conditions on the resulting turbulence and their comparison with solar wind are demonstrated through several kinetic simulations.

  8. Solar wind flow upstream of the coronal slow shock

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.

    1986-01-01

    Slow shocks have been predicted to exist embedded in large coronal holes at low altitude. Two or more curved slow shocks may link together to form a composite discontinuity surface around the sun which may be called the coronal slow shock (CSS). Here a solar-wind model is studied under the assumption that a standing CSS exists and cororates with the sun at a constant angular velocity. A steady, axisymmetrical one-fluid model is introduced to study the expansion of solar wind in the open-field region upstream of the CSS. The model requires that the conditions downstream of the CSS near the equatorial plane can produce a solar wind agreeable with the observations made near the earth's orbit. The paper presents an illustrative calculation in which the polar caps within 60 deg of the polar angle are assumed to be the source region of the solar wind.

  9. Western Wind and Solar Integration Study: Phase 2 (Presentation)

    SciTech Connect

    Lew, D.; Brinkman, G.; Ibanez, E.; Lefton, S.; Kumar, N.; Venkataraman, S.; Jordan, G.

    2013-09-01

    This presentation summarizes the scope and results of the Western Wind and Solar Integration Study Phase 2, which examined operational impacts of high penetrations of variable renewable generation in the West.

  10. Relationship between the sawtooth period and solar wind drivers

    NASA Astrophysics Data System (ADS)

    Cai, X.; Clauer, C. R.; Weimer, D. R.

    2009-12-01

    Cai and Clauer [2009] shows the mean period of sawtooth events has a large variability from 2 to 4 hours, with a mean period around 3 hours. What controls the period, whether by solar wind drivers or internal magnetospheric parameters, is unknown. In this presentation, we examine the relationship between the solar wind drivers and the period for each individual tooth. No clear linear trends are found so we conclude that the period of sawtooth events does not depend on any single solar wind driver exclusively. However sawtooth events driven by stream interaction events have a longer period (~ 180 minutes) than those driven by interplanetary coronal mass ejections (~ 150 minutes). This might suggest the solar wind-magnetosphere system has different coupling efficiencies during these two types of sawtooth events. We also propose an idea to explain why sawtooth events occur periodically and why the Earth has different response modes.

  11. Electrodynamics of solar wind-magnetosphere-ionosphere interactions

    NASA Technical Reports Server (NTRS)

    Kan, Joseph R.; Akasofu, Syun-Ichi

    1989-01-01

    The paper presents a coherent picture of fundamental physical processes in three basic elements of the solar-wind/magnetosphere/ionosphere coupling system: (1) the field-aligned potential structure which leads to the formation of auroral arcs, (2) the magnetosphere-ionosphere coupling which leads to the onset of magnetospheric substorms, and (3) the solar-wind/magnetosphere dynamo which supplies the power driving various magnetospheric processes. Process (1) is forced into existence by the loss-cone constriction effect when the upward field-aligned current density exceeds the loss-cone thermal flux limit. Substorm onset occurs when the ionosphere responds fully to the enhanced magnetospheric convection driven by the solar wind. Energy is transferred from the solar wind to the magnetosphere by a dynamo process, primarily on open field lines.

  12. Transient flows of the solar wind associated with small-scale solar activity in solar minimum

    NASA Astrophysics Data System (ADS)

    Slemzin, Vladimir; Veselovsky, Igor; Kuzin, Sergey; Gburek, Szymon; Ulyanov, Artyom; Kirichenko, Alexey; Shugay, Yulia; Goryaev, Farid

    The data obtained by the modern high sensitive EUV-XUV telescopes and photometers such as CORONAS-Photon/TESIS and SPHINX, STEREO/EUVI, PROBA2/SWAP, SDO/AIA provide good possibilities for studying small-scale solar activity (SSA), which is supposed to play an important role in heating of the corona and producing transient flows of the solar wind. During the recent unusually weak solar minimum, a large number of SSA events, such as week solar flares, small CMEs and CME-like flows were observed and recorded in the databases of flares (STEREO, SWAP, SPHINX) and CMEs (LASCO, CACTUS). On the other hand, the solar wind data obtained in this period by ACE, Wind, STEREO contain signatures of transient ICME-like structures which have shorter duration (<10h), weaker magnetic field strength (<10 nT) and lower proton temperature than usual ICMEs. To verify the assumption that ICME-like transients may be associated with the SSA events we investigated the number of weak flares of C-class and lower detected by SPHINX in 2009 and STEREO/EUVI in 2010. The flares were classified on temperature and emission measure using the diagnostic means of SPHINX and Hinode/EIS and were confronted with the parameters of the solar wind (velocity, density, ion composition and temperature, magnetic field, pitch angle distribution of the suprathermal electrons). The outflows of plasma associated with the flares were identified by their coronal signatures - CMEs (only in few cases) and dimmings. It was found that the mean parameters of the solar wind projected to the source surface for the times of the studied flares were typical for the ICME-like transients. The results support the suggestion that weak flares can be indicators of sources of transient plasma flows contributing to the slow solar wind at solar minimum, although these flows may be too weak to be considered as separate CMEs and ICMEs. The research leading to these results has received funding from the European Union’s Seventh Programme

  13. Large-scale properties of the solar wind in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Khabarova, Olga; Obridko, Vladimir; Zharkova, Valentina; Veselov, Mikhail

    Since the solar wind phenomenon has been revealed and confirmed, one of the most intriguing problems was to understand processes in the solar atmosphere and their relation with the solar wind characteristics at different distances from the Sun. Analysis of multi-spacecraft measurements of plasma parameters and the interplanetary magnetic field provides us with knowledge about the heliosphere from global to small scales. Comparisons of observations with models, describing small-scale processes, usually give more positive results than in the case of models comparison with the solar wind properties at the scales larger than several proton gyroradii. For example, Parker-like models face with big problems in their attempts to predict the solar wind plasma and, especially, the behaviour of the interplanetary magnetic field. Observations show that the radial component of the interplanetary magnetic field depends on heliolatitude and radially decreases with a slope of -5/3 instead of the predicted slope of -2 (Khabarova, Obridko, ApJ, 2012; Khabarova, Astronomy Reports, 2013). This may be determined by small-scale processes occurring in some vicinity of the heliospheric current sheet and related to the magnetic reconnection (Zharkova, Khabarova, ApJ, 2012). In this report we present results of data analysis of eight spacecraft to study variations of plasma, the electric and magnetic field with distance and heliolatitude. begin{enumerate} Zharkova V., Khabarova O., Particle Acceleration in the Reconnecting Heliospheric Current Sheet: Solar Wind Data Versus 3D PIC Simulations, Astrophysical Journal, 2012, V.752, 1, 35 doi:10.1088/0004-637X/752/1/35 begin{enumerate} Khabarova Olga, and Obridko Vladimir, Puzzles of the Interplanetary Magnetic Field in the Inner Heliosphere, 2012, Astrophysical Journal, 761, 2, 82, doi:10.1088/0004-637X/761/2/82 begin{enumerate} Khabarova Olga V., The interplanetary magnetic field: radial and latitudinal dependences. Astronomy Reports, 2013

  14. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells

    NASA Astrophysics Data System (ADS)

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, Junho; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-06-01

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the

  15. Collective capture of released lithium ions in the solar wind

    NASA Technical Reports Server (NTRS)

    Winske, D.; Wu, C. S.; Li, Y. Y.; Zhou, G. C.

    1984-01-01

    The capture of newly ionized lithium ions in the solar wind by means of electromagnetic instabilities is investigated through linear analysis and computer simulation. Three instabilities, driven by a lithium velocity ring perpendicular to and drifting along the magnetic field, are considered. The capture time of the lithium by the solar wind is roughly 10 linear growth times, regardless of whether resonant or nonresonant modes dominate initially. Possible implications of the results for the Active Magnetosphere Particle Tracer Explorer (AMPTE) mission are discussed.

  16. On Electron-Scale Whistler Turbulence in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K.-H.; Motschmann, U.; Giles, B.; Magnes, W.; Fischer, D.; Torbert, R. B.; Russell, C. T.

    2016-01-01

    For the first time, the dispersion relation for turbulence magnetic field fluctuations in the solar wind is determined directly on small scales of the order of the electron inertial length, using four-point magnetometer observations from the Magnetospheric Multiscale mission. The data are analyzed using the high-resolution adaptive wave telescope technique. Small-scale solar wind turbulence is primarily composed of highly obliquely propagating waves, with dispersion consistent with that of the whistler mode.

  17. System identification of geomagnetic disturbances initiated by the solar wind.

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoyan; Tschu, Kangkun

    1991-05-01

    On the basis of linear and time-invariant supposition, the geomagnetic disturbances initiated by the solar wind have been studied in terms of least square non-parametric identification method. The macro-external description of the response of the magnetosphere to the solar wind is given by the impulse response function. The predicted geomagnetic disturbances are compared with the observations; they are found to agree quite well.

  18. Solar wind forcing at Mercury: WSA-ENLIL model results

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.; Poh, Gangkai; Odstrcil, Dusan; Arge, C. Nick; Benna, Mehdi; Johnson, Catherine L.; Korth, Haje; Gershman, Daniel J.; Ho, George C.; McClintock, William E.; Cassidy, Timothy A.; Merkel, Aimee; Raines, Jim M.; Schriver, David; Slavin, James A.; Solomon, Sean C.; TráVníčEk, Pavel M.; Winslow, Reka M.; Zurbuchen, Thomas H.

    2013-01-01

    Analysis and interpretation of observations from the MESSENGER spacecraft in orbit about Mercury require knowledge of solar wind "forcing" parameters. We have utilized the Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool in order to calculate the values of interplanetary magnetic field (IMF) strength (B), solar wind velocity (V) and density (n), ram pressure (~nV2), cross-magnetosphere electric field (V × B), Alfvén Mach number (MA), and other derived quantities of relevance for solar wind-magnetosphere interactions. We have compared upstream MESSENGER IMF and solar wind measurements to see how well the ENLIL model results compare. Such parameters as solar wind dynamic pressure are key for determining the Mercury magnetopause standoff distance, for example. We also use the relatively high-time-resolution B-field data from MESSENGER to estimate the strength of the product of the solar wind speed and southward IMF strength (Bs) at Mercury. This product VBs is the electric field that drives many magnetospheric dynamical processes and can be compared with the occurrence of energetic particle bursts within the Mercury magnetosphere. This quantity also serves as input to the global magnetohydrodynamic and kinetic magnetosphere models that are being used to explore magnetospheric and exospheric processes at Mercury. Moreover, this modeling can help assess near-real-time magnetospheric behavior for MESSENGER or other mission analysis and/or ground-based observational campaigns. We demonstrate that this solar wind forcing tool is a crucial step toward bringing heliospheric science expertise to bear on planetary exploration programs.

  19. Interplanetary stream magnetism: Kinematic effects. [solar magnetic fields and wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Barouch, E.

    1974-01-01

    The particle density, and the magnetic field intensity and direction are calculated in corotating streams of the solar wind, assuming that the solar wind velocity is constant and radial and that its azimuthal variations are not two rapid. The effects of the radial velocity profile in corotating streams on the magnetic fields were examined using kinematic approximation and a variety of field configurations on the inner boundary. Kinematic and dynamic effects are discussed.

  20. Analysis of ISEE-3/ICE solar wind data

    NASA Technical Reports Server (NTRS)

    Coplan, Michael A.

    1989-01-01

    Under the grant that ended November 11, 1988 work was accomplished in a number of areas, as follows: (1) Analysis of solar wind data; (2) Analysis of Giacobini/Zinner encounter data; (3) Investigation of solar wind and magnetospheric electron velocity distributions; and (4) Experimental investigation of the electronic structure of clusters. Reprints and preprints of publications resulting from this work are included in the appendices.

  1. Flow of oxygen ions in the solar wind acceleration region

    NASA Technical Reports Server (NTRS)

    Esser, Ruth; Leer, Egil

    1990-01-01

    A solar wind model with protons, electrons, O VII and O VI ions is studied. It is found that ionization and recombination processes lead to an approximately constant density ratio of the oxygen states in the solar wind acceleration region. Although ionization and recombination have a significant effect on the flow speed of the O VI ions, these processes are not fast enough to bring the speed of O VI up to the flow speed of the O VII ions.

  2. Calculation of solar wind flows about terrestrial planets

    NASA Technical Reports Server (NTRS)

    Stahara, S. S.; Spreiter, J. R.

    1982-01-01

    A computational model was developed for the determination of the plasma and magnetic field properties of the global interaction of the solar wind with terrestrial planetary magneto/ionospheres. The theoretical method is based on an established single fluid, steady, dissipationless, magnetohydrodynamic continuum model, and is appropriate for the calculation of supersonic, super Alfvenic solar wind flow past terrestrial planets. A summary is provided of the important research results.

  3. STEREO Observations of Solar Wind in 2007-2014

    NASA Astrophysics Data System (ADS)

    Jian, Lan; Luhmann, Janet; Russell, Christopher; Blanco-Cano, Xochitl; Kilpua, Emilia; Li, Yan

    2016-04-01

    Since the launch of twin STEREO spacecraft, we have been monitoring the solar wind and providing the Level 3 event lists of large-scale solar wind and particle events to public (http://www-ssc.igpp.ucla.edu/forms/stereo/stereo_level_3.html). The interplanetary coronal mass ejections (ICMEs), stream interaction regions (SIRs), interplanetary shocks, and solar energetic particles (based on high energy telescope data) have been surveyed for 2007-2014 before STEREO A went to the superior solar conjunction and STEREO B was lost in contact. In conjunction with our previous observations of same solar wind structures in 1995-2009 using Wind/ACE data and the same identification criteria, we study the solar cycle variations of these structures, especially compare the same phase of solar cycles 23 and 24. Although the sunspot number at solar maximum 24 is only 60% of the level at last solar maximum, Gopalswamy et al. (2015a, b) found there were more halo CMEs in cycle 24 and the number of magnetic clouds did not decline either. We examine if the two vantage points of STEREO provide a consistent view with the above finding. In addition, because the twin STEREO spacecraft have experienced the full-range longitudinal separation of 0-360 degree, they have provided us numerous opportunities for multipoint observations. We will report the findings on the spatial scope of ICMEs including their driven shocks, and the stability of SIRs from the large event base.

  4. CONTINUUM INTENSITY AND [O i] SPECTRAL LINE PROFILES IN SOLAR 3D PHOTOSPHERIC MODELS: THE EFFECT OF MAGNETIC FIELDS

    SciTech Connect

    Fabbian, D.; Moreno-Insertis, F. E-mail: fmi@iac.es

    2015-04-01

    The importance of magnetic fields in three-dimensional (3D) magnetoconvection models of the Sun’s photosphere is investigated in terms of their influence on the continuum intensity at different viewing inclination angles and on the intensity profile of two [O i] spectral lines. We use the RH numerical radiative transfer code to perform a posteriori spectral synthesis on the same time series of magnetoconvection models used in our publications on the effect of magnetic fields on abundance determination. We obtain a good match of the synthetic disk-center continuum intensity to the absolute continuum values from the Fourier Transform Spectrometer (FTS) observational spectrum; the match of the center-to-limb variation synthetic data to observations is also good, thanks, in part, to the 3D radiation transfer capabilities of the RH code. The different levels of magnetic flux in the numerical time series do not modify the quality of the match. Concerning the targeted [O i] spectral lines, we find, instead, that magnetic fields lead to nonnegligible changes in the synthetic spectrum, with larger average magnetic flux causing both of the lines to become noticeably weaker. The photospheric oxygen abundance that one would derive if instead using nonmagnetic numerical models would thus be lower by a few to several centidex. The inclusion of magnetic fields is confirmed to be important for improving the current modeling of the Sun, here in particular in terms of spectral line formation and of deriving consistent chemical abundances. These results may shed further light on the still controversial issue regarding the precise value of the solar oxygen abundance.

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

    NASA Technical Reports Server (NTRS)

    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.

  6. Potential for Development of Solar and Wind Resource in Bhutan

    SciTech Connect

    Gilman, P.; Cowlin, S.; Heimiller, D.

    2009-09-01

    With support from the U.S. Agency for International Development (USAID), the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) produced maps and data of the wind and solar resources in Bhutan. The solar resource data show that Bhutan has an adequate resource for flat-plate collectors, with annual average values of global horizontal solar radiation ranging from 4.0 to 5.5 kWh/m2-day (4.0 to 5.5 peak sun hours per day). The information provided in this report may be of use to energy planners in Bhutan involved in developing energy policy or planning wind and solar projects, and to energy analysts around the world interested in gaining an understanding of Bhutan's wind and solar energy potential.

  7. Interplanetary shock waves and the structure of solar wind disturbances

    NASA Technical Reports Server (NTRS)

    Hundhausen, A. J.

    1972-01-01

    Observations and theoretical models of interplanetary shock waves are reviewed, with emphasis on the large-scale characteristics of the associated solar wind disturbances and on the relationship of these disturbances to solar activity. The sum of observational knowledge indicates that shock waves propagate through the solar wind along a broad, roughly spherical front, ahead of plasma and magnetic field ejected from solar flares. Typically, the shock front reaches 1 AU about two days after its flare origin, and is of intermediate strength. Not all large flares produce observable interplanetary shock waves; the best indicator of shock production appears to be the generation of both type 2 and type 4 radio bursts by a flare. Theoretical models of shock propagation in the solar wind can account for the typically observed shock strength, transit time, and shape.

  8. Transport of solar wind plasma onto the lunar nightside surface

    NASA Astrophysics Data System (ADS)

    Vorburger, A.; Wurz, P.; Barabash, S.; Futaana, Y.; Wieser, M.; Bhardwaj, A.; Dhanya, M. B.; Asamura, K.

    2016-10-01

    We present first measurements of energetic neutral atoms that originate from solar wind plasma having interacted with the lunar nightside surface. We observe two distinct energetic neutral atom (ENA) distributions parallel to the terminator, the spectral shape, and the intensity of both of which indicate that the particles originate from the bulk solar wind flow. The first distribution modifies the dayside ENA flux to reach ˜6° into the nightside and is well explained by the kinetic temperature of the solar wind protons. The second distribution, which was not predicted, reaches from the terminator to up to 30° beyond the terminator, with a maximum at ˜102° in solar zenith angle. As most likely wake transport processes for this second distribution we identify acceleration by the ambipolar electric field and by the negatively charged lunar nightside surface. In addition, our data provide the first observation indicative of a global solar zenith angle dependence of positive dayside surface potentials.

  9. Investigation of Solar Wind Correlations and Solar Wind Modifications Near Earth by Multi-Spacecraft Observations: IMP 8, WIND and INTERBALL-1

    NASA Technical Reports Server (NTRS)

    Paularena, Karolen I.; Richardson, John D.; Zastenker, Georgy N.

    2002-01-01

    The foundation of this Project is use of the opportunity available during the ISTP (International Solar-Terrestrial Physics) era to compare solar wind measurements obtained simultaneously by three spacecraft - IMP 8, WIND and INTERBALL-1 at wide-separated points. Using these data allows us to study three important topics: (1) the size and dynamics of near-Earth mid-scale (with dimension about 1-10 million km) and small-scale (with dimension about 10-100 thousand km) solar wind structures; (2) the reliability of the common assumption that solar wind conditions at the upstream Lagrangian (L1) point accurately predict the conditions affecting Earth's magnetosphere; (3) modification of the solar wind plasma and magnetic field in the regions near the Earth magnetosphere, the foreshock and the magnetosheath. Our Project was dedicated to these problems. Our research has made substantial contributions to the field and has lead others to undertake similar work.

  10. Wind loading on solar concentrators: Some general considerations

    NASA Technical Reports Server (NTRS)

    Roschke, E. J.

    1984-01-01

    A survey was completed to examine the problems and complications arising from wind loading on solar concentrators. Wind loading is site specific and has an important bearing on the design, cost, performance, operation and maintenance, safety, survival, and replacement of solar collecting systems. Emphasis herein is on paraboloidal, two-axis tracking systems. Thermal receiver problems also are discussed. Wind characteristics are discussed from a general point of view. Current methods for determining design wind speed are reviewed. Aerodynamic coefficients are defined and illustrative examples are presented. Wind tunnel testing is discussed, and environmental wind tunnels are reviewed. Recent results on heliostat arrays are reviewed as well. Aeroelasticity in relation to structural design is discussed briefly.

  11. Wind loading on solar concentrators: Some general considerations

    NASA Astrophysics Data System (ADS)

    Roschke, E. J.

    1984-05-01

    A survey was completed to examine the problems and complications arising from wind loading on solar concentrators. Wind loading is site specific and has an important bearing on the design, cost, performance, operation and maintenance, safety, survival, and replacement of solar collecting systems. Emphasis herein is on paraboloidal, two-axis tracking systems. Thermal receiver problems also are discussed. Wind characteristics are discussed from a general point of view. Current methods for determining design wind speed are reviewed. Aerodynamic coefficients are defined and illustrative examples are presented. Wind tunnel testing is discussed, and environmental wind tunnels are reviewed. Recent results on heliostat arrays are reviewed as well. Aeroelasticity in relation to structural design is discussed briefly.

  12. The Martian interaction with the solar wind: current systems in Mars' ionosphere

    NASA Astrophysics Data System (ADS)

    Brecht, S. H.; Ledvina, S. A.

    2012-12-01

    The presence of the Martian crustal magnetic fields makes a significant modification to the interaction between the solar wind/IMF and the ionosphere of the planet. This paper presents the results of 3-D hybrid simulations of Mars containing the Martian crustal fields. It has already been reported that the addition of the crustal fields makes a significant modification of the ionospheric loss from Mars, Brecht and Ledvina, Earth Planets Space, 64, 165, 2012. This paper focuses on two other aspects of the interaction, the current systems created by the solar wind interaction and the heating of the neutral atmosphere by ion-neutral collisions. The results of several simulations will be analyzed and compared.

  13. Sputtering by the Solar Wind: Effects of Variable Composition

    NASA Technical Reports Server (NTRS)

    Killen, R. M.; Arrell, W. M.; Sarantos, M.; Delory, G. T.

    2011-01-01

    It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that there is no increase in the sputtering yield caused by highly charged heavy ions for metallic and for semiconducting surfaces, but the sputter yield can be noticeably increased in the case of a good insulating surface. Recently measurements of the solar wind composition have become available. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. Whereas many previous calculations of sputtering were limited to the effects of proton bombardment. we show that the heavy ion component. especially the He++ component. can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. We will discuss sputtering of both neutrals and ions.

  14. Western Wind and Solar Integration Study Phase 2: Preprint

    SciTech Connect

    Lew, D.; Brinkman, G.; Ibanez, E.; Hodge, B.-M.; King, J.

    2012-09-01

    The Western Wind and Solar Integration Study (WWSIS) investigates the impacts of high penetrations of wind and solar power into the Western Interconnection of the United States. WWSIS2 builds on the Phase 1 study but with far greater refinement in the level of data inputs and production simulation. It considers the differences between wind and solar power on systems operations. It considers mitigation options to accommodate wind and solar when full costs of wear-and-tear and full impacts of emissions rates are taken into account. It determines wear-and-tear costs and emissions impacts. New data sets were created for WWSIS2, and WWSIS1 data sets were refined to improve realism of plant output and forecasts. Four scenarios were defined for WWSIS2 that examine the differences between wind and solar and penetration level. Transmission was built out to bring resources to load. Statistical analysis was conducted to investigate wind and solar impacts at timescales ranging from seasonal down to 5 minutes.

  15. Using the fingerprints of solar magnetic reconnection to identify the elemental building blocks of the slow solar wind

    NASA Astrophysics Data System (ADS)

    Kepko, Larry; Viall, Nicholeen M.; Kasper, Justin; Lepri, Sue

    2015-04-01

    While the source of the fast solar wind is well understood to be linked to coronal holes, the source of the slow solar wind has remained elusive. Many previous studies of the slow solar wind have examined trends in the composition and charge states over long time scales and found strong relationships between the solar wind velocity and these plasma parameters. These relationships have been used to constrain models of solar wind source and acceleration. In this study, we take advantage of high time resolution (12 min) measurements of solar wind composition and charge-state abundances recently reprocessed by the ACE Solar Wind Ion Composition Spectrometer (SWICS) science team to probe the timescales of solar wind variability at relatively small scales. We study an interval of slow solar wind containing quasi-periodic 90 minute structures and show that they are remnants of solar magnetic reconnection. Each 90-minute parcel of slow solar wind, though the speed remains steady, exhibits the complete range of charge state and composition variations expected for the entire range of slow solar wind, which is repeated again in the next 90-minute interval. These observations show that previous statistical results break down on these shorter timescales, and impose new and important constraints on models of slow solar wind creation. We conclude by suggesting these structures were created through interchange magnetic reconnection and form elemental building blocks of the slow solar wind. We also discuss the necessity of decoupling separately the process(es) responsible for the release and acceleration.

  16. Surface-effect corrections for solar-like oscillations using 3D hydrodynamical simulations. I. Adiabatic oscillations

    NASA Astrophysics Data System (ADS)

    Sonoi, T.; Samadi, R.; Belkacem, K.; Ludwig, H.-G.; Caffau, E.; Mosser, B.

    2015-11-01

    Context. The CoRoT and Kepler space-borne missions have provided us with a wealth of high-quality observational data that allows for seismic inferences of stellar interiors. This requires the computation of precise and accurate theoretical frequencies, but imperfect modeling of the uppermost stellar layers introduces systematic errors. To overcome this problem, an empirical correction has been introduced by Kjeldsen et al. (2008, ApJ, 683, L175) and is now commonly used for seismic inferences. Nevertheless, we still lack a physical justification allowing for the quantification of the surface-effect corrections. Aims: Our aim is to constrain the surface-effect corrections across the Hertzsprung-Russell (HR) diagram using a set of 3D hydrodynamical simulations. Methods: We used a grid of these simulations computed with the CO5BOLD code to model the outer layers of solar-like stars. Upper layers of the corresponding 1D standard models were then replaced by the layers obtained from the horizontally averaged 3D models. The frequency differences between these patched models and the 1D standard models were then calculated using the adiabatic approximation and allowed us to constrain the Kjeldsen et al. power law, as well as a Lorentzian formulation. Results: We find that the surface effects on modal frequencies depend significantly on both the effective temperature and the surface gravity. We further provide the variation in the parameters related to the surface-effect corrections using their power law as well as a Lorentzian formulation. Scaling relations between these parameters and the elevation (related to the Mach number) is also provided. The Lorentzian formulation is shown to be more robust for the whole frequency spectrum, while the power law is not suitable for the frequency shifts in the frequency range above νmax. Finally, we show that, owing to turbulent pressure, the elevation of the uppermost layers modifies the location of the hydrogen ionization zone and

  17. Interaction of Comets and the Solar Wind

    NASA Technical Reports Server (NTRS)

    Wagner, William (Technical Monitor); Raymond, John C.

    2003-01-01

    We had originally planned to analyze UVCS observations of Comet Machholz, but we obtained higher quality observations of Comet Kudo-Fujikawa in January 2003 at its 0.19 AU perihelion. Besides a large and rapidly increasing water outgassing rate, we detected a bright tail in doubly ionized carbon. The amount of carbon was greater than could be accounted for by GO photodissociation, and we attribute the carbon to evaporation of organics from dust. A spectacular disconnection event was apparent in the C III tail, and it coincides within the uncertainties with the position of the heliospheric current sheet. A paper is in press in Science, and it will be the subject of a press release. We are also analyzing two sungrazing comets. Comet C/2001 C2 shows evidence for sub-fragments and for a very long lasting source of neutrals, which we tentatively identify as evaporation of pyroxene dust grains. Comet C/2002 S2 shows a sudden 2 magnitude drop in optical brightness and an equally sudden recovery. UVCS observations during that time show a steadily increasing outgassing rate. We have derived solar wind densities for both comets, but we are still sorting out the ambiguities involving the fragmentation and optical behavior. We are collaborating with Philippe Lamy on the LASCO measurements.

  18. Interaction of Comets and the Solar Wind

    NASA Technical Reports Server (NTRS)

    Wagner, William (Technical Monitor); Raymond, John C.

    2004-01-01

    The analysis of Comet Kudo-Fujikawa at perihelion was published and picked up by Der Spiegel. Besides a large and rapidly increasing water outgassing rate, we detected a bright tail in doubly ionized carbon. The amount of carbon was greater than could be accounted for by CO photodissociation, and we attribute it to evaporation of organics from dust. A spectacular disconnection event was apparent in the C III tail, and it coincides within the uncertainties to the position of the heliospheric current sheet. The analysis of the sungrazing comet C2001 C2 is in press. It showed evidence for subfragments and for a very long lasting source of neutrals, which we identify as evaporation of pyroxene dust grains. Results were also presented at COSPAR. We are working on observations of another sungrazer, comet C2002 S2, which shows a sudden 2 magnitude drop in optical brightness and an equally sudden recovery. UVCS observations during that time show a steadily increasing outgassing rate. We have derived solar wind densities for both comets, but we are still sorting out the ambiguities involving the fragmentation and optical behavior.

  19. Prediction of solar energetic particle event histories using real-time particle and solar wind measurements

    NASA Technical Reports Server (NTRS)

    Roelof, E. C.; Gold, R. E.

    1978-01-01

    The comparatively well-ordered magnetic structure in the solar corona during the decline of Solar Cycle 20 revealed a characteristic dependence of solar energetic particle injection upon heliographic longitude. When analyzed using solar wind mapping of the large scale interplanetary magnetic field line connection from the corona to the Earth, particle fluxes display an approximately exponential dependence on heliographic longitude. Since variations in the solar wind velocity (and hence the coronal connection longitude) can severely distort the simple coronal injection profile, the use of real-time solar wind velocity measurements can be of great aid in predicting the decay of solar particle events. Although such exponential injection profiles are commonplace during 1973-1975, they have also been identified earlier in Solar Cycle 20, and hence this structure may be present during the rise and maximum of the cycle, but somewhat obscured by greater temporal variations in particle injection.

  20. Impacts of wind stilling on solar radiation variability in China.

    PubMed

    Lin, Changgui; Yang, Kun; Huang, Jianping; Tang, Wenjun; Qin, Jun; Niu, Xiaolei; Chen, Yingying; Chen, Deliang; Lu, Ning; Fu, Rong

    2015-10-14

    Solar dimming and wind stilling (slowdown) are two outstanding climate changes occurred in China over the last four decades. The wind stilling may have suppressed the dispersion of aerosols and amplified the impact of aerosol emission on solar dimming. However, there is a lack of long-term aerosol monitoring and associated study in China to confirm this hypothesis. Here, long-term meteorological data at weather stations combined with short-term aerosol data were used to assess this hypothesis. It was found that surface solar radiation (SSR) decreased considerably with wind stilling in heavily polluted regions at a daily scale, indicating that wind stilling can considerably amplify the aerosol extinction effect on SSR. A threshold value of 3.5 m/s for wind speed is required to effectively reduce aerosols concentration. From this SSR dependence on wind speed, we further derived proxies to quantify aerosol emission and wind stilling amplification effects on SSR variations at a decadal scale. The results show that aerosol emission accounted for approximately 20% of the typical solar dimming in China, which was amplified by approximately 20% by wind stilling.

  1. Implications of the Deep Minimum for Slow Solar Wind Origin

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    The origin of the slow solar wind has long been one of the most important problems in solar/heliospheric physics. Two observational constraints make this problem especially challenging. First, the slow wind has the composition of the closed-field corona, unlike the fast wind that originates on open field lines. Second, the slow wind has substantial angular extent, of order 30 degrees, which is much larger than the widths observed for streamer stalks or the widths expected theoretically for a dynamic heliospheric current sheet. We propose that the slow wind originates from an intricate network of narrow (possibly singular) open-field corridors that emanate from the polar coronal hole regions. Using topological arguments, we show that these corridors must be ubiquitous in the solar corona. The total solar eclipse in August 2008, near the lowest point of the Deep Minimum, affords an ideal opportunity to test this theory by using the ultra-high resolution Predictive Science's (PSI) eclipse model for the corona and wind. Analysis of the PSI eclipse model demonstrates that the extent and scales of the open-field corridors can account for both the angular width of the slow wind and its closed-field composition. We discuss the implications of our slow wind theory for the structure of the corona and heliosphere at the Deep Minimum and describe further observational and theoretical tests. This work has been supported by the NASA HTP, SR&T, and LWS programs.

  2. Impacts of wind stilling on solar radiation variability in China

    PubMed Central

    Lin, Changgui; Yang, Kun; Huang, Jianping; Tang, Wenjun; Qin, Jun; Niu, Xiaolei; Chen, Yingying; Chen, Deliang; Lu, Ning; Fu, Rong

    2015-01-01

    Solar dimming and wind stilling (slowdown) are two outstanding climate changes occurred in China over the last four decades. The wind stilling may have suppressed the dispersion of aerosols and amplified the impact of aerosol emission on solar dimming. However, there is a lack of long-term aerosol monitoring and associated study in China to confirm this hypothesis. Here, long-term meteorological data at weather stations combined with short-term aerosol data were used to assess this hypothesis. It was found that surface solar radiation (SSR) decreased considerably with wind stilling in heavily polluted regions at a daily scale, indicating that wind stilling can considerably amplify the aerosol extinction effect on SSR. A threshold value of 3.5 m/s for wind speed is required to effectively reduce aerosols concentration. From this SSR dependence on wind speed, we further derived proxies to quantify aerosol emission and wind stilling amplification effects on SSR variations at a decadal scale. The results show that aerosol emission accounted for approximately 20% of the typical solar dimming in China, which was amplified by approximately 20% by wind stilling. PMID:26463748

  3. Coronal hole structure and the high speed solar wind

    NASA Technical Reports Server (NTRS)

    Holzer, Thomas E.; Leer, Egil

    1997-01-01

    The basic physical processes which are important in the acceleration of high speed wind from coronal holes are reviewed. The early works of Birkeland and Parker are discussed. The extension of Parker's work is included. It is shown that the greatest area of uncertainty is that of coronal heating. It is demonstrated that in modeling solar wind acceleration, it is important to carry out a study on the chromosphere-corona-wind system analysis.

  4. Computation of Solar Radiative Fluxes by 1D and 3D Methods Using Cloudy Atmospheres Inferred from A-train Satellite Data

    NASA Technical Reports Server (NTRS)

    Barker, Howard W.; Kato, Serji; Wehr, T.

    2012-01-01

    The main point of this study was to use realistic representations of cloudy atmospheres to assess errors in solar flux estimates associated with 1D radiative transfer models. A scene construction algorithm, developed for the EarthCARE satellite mission, was applied to CloudSat, CALIPSO, and MODIS satellite data thus producing 3D cloudy atmospheres measuring 60 km wide by 13,000 km long at 1 km grid-spacing. Broadband solar fluxes and radiances for each (1 km)2 column where then produced by a Monte Carlo photon transfer model run in both full 3D and independent column approximation mode (i.e., a 1D model).

  5. Constraints on neon and argon isotopic fractionation in solar wind.

    PubMed

    Meshik, Alex; Mabry, Jennifer; Hohenberg, Charles; Marrocchi, Yves; Pravdivtseva, Olga; Burnett, Donald; Olinger, Chad; Wiens, Roger; Reisenfeld, Dan; Allton, Judith; McNamara, Karen; Stansbery, Eileen; Jurewicz, Amy J G

    2007-10-19

    To evaluate the isotopic composition of the solar nebula from which the planets formed, the relation between isotopes measured in the solar wind and on the Sun's surface needs to be known. The Genesis Discovery mission returned independent samples of three types of solar wind produced by different solar processes that provide a check on possible isotopic variations, or fractionation, between the solar-wind and solar-surface material. At a high level of precision, we observed no significant inter-regime differences in 20Ne/22Ne or 36Ar/38Ar values. For 20Ne/22Ne, the difference between low- and high-speed wind components is 0.24 +/- 0.37%; for 36Ar/38Ar, it is 0.11 +/- 0.26%. Our measured 36Ar/38Ar ratio in the solar wind of 5.501 +/- 0.005 is 3.42 +/- 0.09% higher than that of the terrestrial atmosphere, which may reflect atmospheric losses early in Earth's history.

  6. Electron energy transport in the solar wind: Ulysses observations

    NASA Technical Reports Server (NTRS)

    Scime, Earl; Gary, S. Peter; Phillips, J. L.; Corniileau-Wehrlin, N.; Solomon, J.

    1995-01-01

    The electron heat flux in the solar wind has been measured by the Ulysses solar wind plasma experiment in the ecliptic from 1 to 5 AU and out of the ecliptic during the recently completed pass over the solar south pole and the ongoing pass over the solar north pole. Although the electron heat flux contains only a fraction of the kinetic energy of the solar wind. the available energy is sufficient to account for the non-adiabatic expansion of the solar wind electrons. The Ulysses measurements indicate that the electron heat flux is actively dissipated in the solar wind. The exact mechanism or mechanisms is unknown. but a model based on the whistler heat flux instability predicts radial gradients for the electron heat flux in good agreement with the data. We will present measurements of the correlation between wave activity measured by the unified radio and plasma experiment (URAP) and the electron heat flux throughout the Ulysses mission. The goal is to determine if whistler waves are a good candidate for the observed electron heat flux dissipation. The latitudinal gradients of the electron heat flux. wave activity. and electron pressure will be discussed in light of the changes in the magnetic field geometry from equator to poles.

  7. Solar wind eddies and the heliospheric current sheet

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Mccomas, D. J.; Bame, S. J.; Goldstein, B. E.

    1995-01-01

    Ulysses has collected data between 1 and 5 AU during, and just following solar maximum, when the heliospheric current sheet (HCS) can be thought of as reaching its maximum tilt and being subject to the maximum amount of turbulence in the solar wind. The Ulysses solar wind plasma instrument measures the vector velocity and can be used to estimate the flow speed and direction in turbulent 'eddies' in the solar wind that are a fraction of an astronomical unit in size and last (have either a turnover or dynamical interaction time of) several hours to more than a day. Here, in a simple exercise, these solar wind eddies at the HCS are characterized using Ulysses data. This character is then used to define a model flow field with eddies that is imposed on an ideal HCS to estimate how the HCS will be deformed by the flow. This model inherently results in the complexity of the HCS increasing with heliocentric distance, but the result is a measure of the degree to which the observed change in complexity is a measure of the importance of solar wind flows in deforming the HCS. By comparison with randomly selected intervals not located on the HCS, it appears that eddies on the HCS are similar to those elsewhere at this time during the solar cycle, as is the resultant deformation of the interplanetary magnetic field (IMF). The IMF deformation is analogous to what is often termed the 'random walk' of interplanetary magnetic field lines.

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

    NASA Astrophysics Data System (ADS)

    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

  9. Solar flare acceleration of solar wind: influence of active region magnetic field.

    PubMed

    Lundstedt, H; Wilcox, J M; Scherrer, P H

    1981-06-26

    The direction of the photospheric magnetic field at the site of a solar flare is a good predictor of whether the flare will accelerate solar wind plasma. If the field has a southward component, high-speed solar wind plasma is usually observed near the earth about 4 days later. If the field has a northward component, such high-speed solar wind is almost never observed. Southward-field flares may then be expected to have much larger terrestrial effects than northward flares.

  10. On the Relationship Between Solar Wind Speed, Geomagnetic Activity, and the Solar Cycle Using Annual Values

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    The aa index can be decomposed into two separate components: the leading sporadic component due to solar activity as measured by sunspot number and the residual or recurrent component due to interplanetary disturbances, such as coronal holes. For the interval 1964-2006, a highly statistically important correlation (r = 0.749) is found between annual averages of the aa index and the solar wind speed (especially between the residual component of aa and the solar wind speed, r = 0.865). Because cyclic averages of aa (and the residual component) have trended upward during cycles 11-23, cyclic averages of solar wind speed are inferred to have also trended upward.

  11. Solar and Solar-Wind Composition Results from the Genesis Mission

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Burnett, D. S.; Hohenberg, C. M.; Meshik, A.; Heber, V.; Grimberg, A.; Wieler, R.; Reisenfeld, D. B.

    The Genesis mission returned samples of solar wind to Earth in September 2004 for ground-based analyses of solar-wind composition, particularly for isotope ratios. Substrates, consisting mostly of high-purity semiconductor materials, were exposed to the solar wind at L1 from December 2001 to April 2004. In addition to a bulk sample of the solar wind, separate samples of coronal hole (CH), interstream (IS), and coronal mass ejection material were obtained. Although many substrates were broken upon landing due to the failure to deploy the parachute, a number of results have been obtained, and most of the primary science objectives will likely be met. These objectives include He, Ne, Ar, Kr, and Xe isotope ratios in the bulk solar wind and in different solar-wind regimes, and 15N/14N and 18O/17O/16O to high precision. The greatest successes to date have been with the noble gases. Light noble gases from bulk solar wind and separate solar-wind regime samples have now been analyzed. Helium results show clear evidence of isotopic fractionation between CH and IS samples, consistent with simplistic Coulomb drag theory predictions of fractionation between the photosphere and different solar-wind regimes, though fractionation by wave heating is also a possible explanation. Neon results from closed system stepped etching of bulk metallic glass have revealed the nature of isotopic fractionation as a function of depth, which in lunar samples have for years deceptively suggested the presence of an additional, energetic component in solar wind trapped in lunar grains and meteorites. Isotope ratios of the heavy noble gases, nitrogen, and oxygen are in the process of being measured.

  12. Solar and Solar-Wind Composition Results from the Genesis Mission

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Burnett, D. S.; Hohenberg, C. M.; Meshik, A.; Heber, V.; Grimberg, A.; Wieler, R.; Reisenfeld, D. B.

    2007-06-01

    The Genesis mission returned samples of solar wind to Earth in September 2004 for ground-based analyses of solar-wind composition, particularly for isotope ratios. Substrates, consisting mostly of high-purity semiconductor materials, were exposed to the solar wind at L1 from December 2001 to April 2004. In addition to a bulk sample of the solar wind, separate samples of coronal hole (CH), interstream (IS), and coronal mass ejection material were obtained. Although many substrates were broken upon landing due to the failure to deploy the parachute, a number of results have been obtained, and most of the primary science objectives will likely be met. These objectives include He, Ne, Ar, Kr, and Xe isotope ratios in the bulk solar wind and in different solar-wind regimes, and 15N/14N and 18O/17O/16O to high precision. The greatest successes to date have been with the noble gases. Light noble gases from bulk solar wind and separate solar-wind regime samples have now been analyzed. Helium results show clear evidence of isotopic fractionation between CH and IS samples, consistent with simplistic Coulomb drag theory predictions of fractionation between the photosphere and different solar-wind regimes, though fractionation by wave heating is also a possible explanation. Neon results from closed system stepped etching of bulk metallic glass have revealed the nature of isotopic fractionation as a function of depth, which in lunar samples have for years deceptively suggested the presence of an additional, energetic component in solar wind trapped in lunar grains and meteorites. Isotope ratios of the heavy noble gases, nitrogen, and oxygen are in the process of being measured.

  13. Global solar wind variations over the last four centuries.

    PubMed

    Owens, M J; Lockwood, M; Riley, P

    2017-01-31

    The most recent "grand minimum" of solar activity, the Maunder minimum (MM, 1650-1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth's magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima.

  14. Global solar wind variations over the last four centuries

    PubMed Central

    Owens, M. J.; Lockwood, M.; Riley, P.

    2017-01-01

    The most recent “grand minimum” of solar activity, the Maunder minimum (MM, 1650–1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth’s magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima. PMID:28139769

  15. Global solar wind variations over the last four centuries

    NASA Astrophysics Data System (ADS)

    Owens, M. J.; Lockwood, M.; Riley, P.

    2017-01-01

    The most recent “grand minimum” of solar activity, the Maunder minimum (MM, 1650–1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth’s magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima.

  16. Comparing Solar Wind Velocity Measurements Derived from Sun-grazing Comet Lovejoy (C/2011 W3) with Solar Wind Models

    NASA Astrophysics Data System (ADS)

    Ramanjooloo, Y.; Jones, G. H.; Coates, A. J.; Owens, M. J.; Battams, K.

    2012-12-01

    Comets' plasma (type I) tails have been studied as natural probes of the solar wind since the mid-20th century. Local solar wind conditions directly control the morphology and dynamics of a comet's plasma tail. During ideal observing geometries, the orientation and structure of the plasma tail can reveal large-scale and small-scale variations in the local solar wind structure. We present solar wind velocity measurements derived from multiple observing locations of comet Lovejoy (C/2011 W3) from the 14th - 19th December 2011 using recent images from the SECCHI and LASCO heliospheric imagers and coronagraphs aboard STEREO A and B, and SOHO. Overlapping observation sessions from the three spacecraft provided the perfect opportunity to use comet Lovejoy as a diagnostic tool to understand solar wind variability close to the Sun. Our unique analysis technique [submitted] allows us to determine the latitudinal variations of the solar wind, heliospheric current sheet sector boundaries and the boundaries of transient features as comet Lovejoy probes the Sun's atmosphere. We plan to compare our observations to results of suitable simulations of plasma conditions in the corona and inner heliosphere during the time of Lovejoy's perihelion passage.

  17. A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 - 24 Minimum

    NASA Astrophysics Data System (ADS)

    Liou, Kan; Wu, Chin-Chun

    2016-12-01

    Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23 - 24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth's orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind region (SWR) can have a direct influence on the solar wind parameters near the Earth. In this study, we analyze solar wind plasma and magnetic field data of hourly values acquired by Ulysses. It is found that the solar wind, when averaging over the first (1995.6 - 1995.8) and third (2006.9 - 2008.2) Ulysses' perihelion ({˜} 1.4 AU) crossings, was about the same speed, but significantly less dense ({˜} 34 %) and cooler ({˜} 20 %), and the total magnetic field was {˜} 30 % weaker during the third compared to the first crossing. It is also found that the SWR was {˜} 50 % wider in the third ({˜} 68.5^deg; in heliographic latitude) than in the first ({˜} 44.8°) solar orbit. The observed latitudinal increase in the SWR is sufficient to explain the excessive decline in the near-Earth solar wind density during the recent solar minimum without speculating that the total solar output may have been decreasing. The observed SWR inflation is also consistent with a cooler solar wind in the SC-23/24 than in the SC-22/23 minimum. Furthermore, the ratio of the high-to-low latitude photospheric magnetic field (or equatorward magnetic pressure force), as observed by the Mountain Wilson Observatory, is smaller during the third than the first Ulysses' perihelion orbit. These findings suggest that the smaller equatorward magnetic pressure at the Sun may have led to the latitudinally-wider SRW observed by Ulysses in SC-23/24 minimum.

  18. Scale-free texture of the fast solar wind.

    PubMed

    Hnat, B; Chapman, S C; Gogoberidze, G; Wicks, R T

    2011-12-01

    The higher-order statistics of magnetic field magnitude fluctuations in the fast quiet solar wind are quantified systematically, scale by scale. We find a single global non-Gaussian scale-free behavior from minutes to over 5 h. This spans the signature of an inertial range of magnetohydrodynamic turbulence and a ~1/f range in magnetic field components. This global scaling in field magnitude fluctuations is an intrinsic component of the underlying texture of the solar wind and puts a strong constraint on any theory of solar corona and the heliosphere. Intriguingly, the magnetic field and velocity components show scale-dependent dynamic alignment outside of the inertial range.

  19. Shear flow induced wave couplings in the solar wind

    SciTech Connect

    Poedts, S.; Rogava, A.D. |; Mahajan, S.M. |

    1998-01-01

    A sheared background flow in a plasma induces coupling between different MHD wave modes, resulting in their mutual transformations with corresponding energy redistributing between the modes. In this way, the energy can be transfered from one wave mode to the other, but energy can also be added to or extracted from the background flow. In the present paper it is investigated whether the wave coupling and energy transfer mechanisms can operate under solar wind conditions. It is shown that this is indeed the case. Hence, the long-period waves observed in the solar wind at r > 0.3 AU might be generated by much faster periodic oscillations in the photosphere of the Sun. Other possible consequences for observable beat phenomena in the wind and the acceleration of the solar wind particles are also discussed.

  20. Coronal Streamers and Their Associated Solar Wind Streams

    NASA Astrophysics Data System (ADS)

    Miralles, M. P.; Landi, E.; Cranmer, S. R.; Cohen, O.; Raymond, J. C.

    2012-12-01

    We use the EUV spectrometers aboard SOHO and Hinode and white-light coronagraphs to characterize the physical properties of coronal streamers during Earth/Ulysses quadrature configurations for the previous two solar minimum periods. In addition, comparisons between coronal observations and in situ measurements of solar wind plasma properties are being used to further characterize the origins of slow wind streams. In order to investigate slow solar wind heating and acceleration, we also compare with predictions from three-dimensional MHD models. We aim to use the empirical measurements to distinguish between different proposed physical processes for slow wind acceleration (e.g., waves/turbulence versus reconnection). This work is supported by NASA grant NNX10AQ58G to the Smithsonian Astrophysical Observatory.

  1. Solar Wind Stream Interaction Regions without Sector Boundaries

    NASA Technical Reports Server (NTRS)

    Neugebauer, M.; Liewer, P. C.; Goldstein, B. E.; Zhou., X.; Steinberg, J. T.

    2004-01-01

    During periods of high solar activity when there are many sources of solar wind on the solar disk, a spacecraft occasionally encounters consecutive solar wind streams with the same magnetic polarity. The low-speed wind in the region of interaction between the two streams exhibits many of the same features as, but has some differences from, the low-speed wind that includes crossings of the heliospheric current sheet (HCS) where the direction of the heliospheric magnetic field reverses. The non-HCS slow wind exhibits many of the same small-scale structures usually associated with the slow wind around the HCS; these include discontinuous stream interfaces and other discontinuities, magnetic holes, and low-entropy structures. These entropy holes do not appear to have the same origin as the plasma sheets observed near the HCS, however. The helium abundances and heavy ion charge states in the non-HCS regions are not significantly different from those in HCS-associated regions. Some of the dynamical properties of the non-HCS regions differ from those found near the HCS; the regions between leading and trailing stream interfaces have a shorter duration or scale size, greater minimum speed, and lower peak and average densities. No correlation could be found between the non-HCS slow wind and visible coronal streamers.

  2. IMPRINTS OF EXPANSION ON THE LOCAL ANISOTROPY OF SOLAR WIND TURBULENCE

    SciTech Connect

    Verdini, Andrea; Grappin, Roland

    2015-08-01

    We study the anisotropy of II-order structure functions (SFs) defined in a frame attached to the local mean field in three-dimensional (3D) direct numerical simulations of magnetohydrodynamic turbulence, with the solar wind expansion both included and not included. We simulate spacecraft flybys through the numerical domain by taking increments along the radial (wind) direction that form an angle of 45° with the ambient magnetic field. We find that only when expansion is taken into account do the synthetic observations match the 3D anisotropy observed in the solar wind, including the change of anisotropy with scale. Our simulations also show that the anisotropy changes dramatically when considering increments oblique to the radial directions. Both results can be understood by noting that expansion reduces the radial component of the magnetic field at all scales, thus confining fluctuations in the plane perpendicular to the radial. Expansion is thus shown to affect not only the (global) spectral anisotropy, but also the local anisotropy of second-order SF by influencing the distribution of the local mean field, which enters this higher-order statistics.

  3. Numerical study of the propagation characteristics of coronal mass ejections in a structured ambient solar wind

    NASA Astrophysics Data System (ADS)

    Zhou, Yufen; Feng, Xueshang

    2017-02-01

    Using a three-dimensional (3-D) magnetohydrodynamics (MHD) model, we analyze and study the propagation characteristics of coronal mass ejections (CMEs) launched at different positions in a realistic structured ambient solar wind. Here the ambient solar wind structure during the Carrington rotation 2095 is selected, which is the characteristics of activity rising phase. CMEs with a simple spherical plasmoid structure are initiated at different solar latitudes with respect to the heliospheric current sheet (HCS) and the Earth in the same ambient solar wind. Then, we numerically obtained the evolution process of the CMEs from the Sun to the interplanetary space. When the Earth and the CME launch position are located on the same side of the HCS, the arrival time of the shock at the Earth is faster than that when the Earth and the CME launch position are located on the opposite side of the HCS. The disturbance amplitudes for the same side event are also larger than those for the opposite side event. This may be due to the fact that the HCS between the CME and the Earth for the opposite side event hinders its propagation and weaken it. The CMEs tend to deflect toward the HCS in the latitudinal direction near the corona and then propagate almost parallel to the HCS in the interplanetary space. This deflecting tendency may be caused by the dynamic action of near-Sun magnetic pressure gradient force on the ejected coronal plasma.

  4. Radio interferometer measurements of turbulence in the inner solar wind

    NASA Technical Reports Server (NTRS)

    Spangler, S. R.; Sakurai, T.; Coles, William A.; Grall, R. R.; Harmon, J. K.

    1995-01-01

    Measurements can be made of Very Long Baseline Interferometer (VLBI) phase scintillations due to plasma turbulence in the solar corona and solar wind. These measurements provide information on the spectrum and intensity of density fluctuations with scale sizes of a few hundred to several thousand kilometers. If we model the spatial power spectrum of the density fluctuations as P(sub delta n)(q) = C(sup 2)(sub N) q(sup -alpha), where q is the spatial wavenumber, these observations yield both alpha and the path-integrated value of C(sup 2)(sub N). The recently completed Very Long Baseline Array (VLBA) is capable of making such measurements over the heliocentric distance range from a few solar radii to 60 solar radii and beyond. This permits the determination with the same technique and instrument of the radial evolution of turbulent characteristics, as well as their dependence on solar wind transients, sector structure, etc. In this paper we present measurements of 13 sources observed at a wide range of solar elongations, and at different times. These observations show that the coefficient C(sup 2(sub N), depends on heliocentric distance as approximately C(sup 2)(sub N) varies as (R/Solar Radius)(sup -3.7). The radio derived power spectral characteristics are in agreement with in situ measurements by the Helios spacecraft for regions of slow solar wind, but fast solar wind does not have large enough density fluctuations to account for the magnitude of the observed scintillations. The observed radial dependence is consistent with a WKB-type evolution of the turbulence with heliocentric distance. Our data also show indication of turbulence enhancement associated with solar wind transients.

  5. The Generation of Smooth High Speed Solar Wind from Plume-Interplume Mixing

    NASA Technical Reports Server (NTRS)

    Parhi, Shyamsundar; Suess, Steven T.; Sulkanen, Martin E.

    1998-01-01

    Plumes and rays are magnetic field aligned density striations in coronal holes with different values of plasma beta. The overall plasma beta is very small in the low corona but exceeds unity beyond 15-20 solar radius. High speed solar wind reported beyond 0.3 AU is relatively smooth and uniform and known to originate from the much filamented coronal hole. Thus the obvious question is how to generate a smooth solar wind from seemingly filamentary structure. Hence one has to find a mechanism to substantiate this apparent observed (Ulysses) phenomenon. To do this we model plumes as jets (or wakes) of plasma emitted from the solar surface. The shear between a jet and its ambient is known to become unstable to the MHD Kelvin-Helmholtz ("KH") instability if the Alfven Mach number of the jet is greater than one and the uniform external magnetic field is small. Starting with a simple configuration we consider a jet of half thickness R, having uniform density and uniform internal magnetic field. The external medium has also a uniform density and uniform magnetic field. The jet is perturbed at the boundary with a linear amplitude and fixed frequency. We simulate the coronal jet using the 3D ZEUS code. The first results indicate the slab jet is unstable to the MHD KH instability at 5-10 solar radius for some angle of wave propagation. The propagating instability may smooth the filamented flow. It may also produce the entrained Alfvenic fluctuations observed by Ulysses in the high speed wind. We are at present determining the parameters which induce large growth rate. This may clarify the mystery behind the emergence of fast smooth solar wind from very filamentary structures in coronal holes. Also, using the dispersion relation already available for such a flow we obtain some general description of the instability criteria for the KH instability at a jet interface.

  6. Continuing the Search for Natural Solar Wind States

    NASA Astrophysics Data System (ADS)

    Roberts, D. A.; Sipes, T.; Karimabadi, H.

    2015-12-01

    The need to classify solar wind states is partially the practical one of knowing what winds will strongly affect the Earth, but it is also to help in understanding the origin of the winds. In terms of the latter classification, of interest here, there is general agreement that "ejecta" represent a separate class from ordinary winds, although the details of which parcels qualify as ejecta are still subject to considerable disagreement. It has become clear that the distinction between "slow" and "fast" wind is at best misleading, and slow wind sometimes displays temperature anisotropies, fluctuation spectra, and the like that are characteristic of the typical fast wind. Recent work has focused on distinguishing "coronal hole wind" from "streamer belt" and "strahl confusion zone" (heliospheric current sheet) winds. The hope is to discern which wind comes from coronal holes versus the boundaries of holes versus near active regions or other sources. The present work extends a simple method of clustering in the parameter space of a selected set of variables to see if "natural" states of wind arise. This method (primarily "K-means" but we are also trying others) has proven capable of distinguishing states very similar to those in recent categorizations, especially when the variables of cross-helicity and residual energy are added to the parameter list, but we also find new, persistent, categories. The present work will look in more detail at the derived states and at different times in the solar cycle. One suggestion in the research so far is that shock-like structures are fundamental in the mix; these have largely been ignored in recent work in solar wind heating.

  7. Collecting Samples of Coronal and Solar Wind Plasma with Solar Probe Plus

    NASA Astrophysics Data System (ADS)

    Kasper, J. C.; Solar Wind Electrons Alphas; Protons (Sweap) Team

    2011-12-01

    The primary science objective of the NASA Solar Probe Plus mission is to determine the structure and dynamics of the Sun's coronal magnetic field and to understand how the corona and solar wind are heated and accelerated and how energetic particles are produced and evolve. To accomplish this, the spacecraft carries a broad payload of in situ and remote sensing instruments and uses a sequence of Venus gravitational assists to dive within 8.5 solar radii of the surface of the Sun, making it the first spacecraft to enter the sub-Alfvénic solar corona. This talk will focus on measurements of the thermal ions and electrons that constitute the bulk of the solar corona and solar wind, covering open questions related to the structure, heating, and acceleration of the solar corona and solar wind. The Solar Wind Electrons Alphas and Protons (SWEAP) Investigation on Solar Probe Plus will be presented, including a description of how measurements from electrostatic analyzers behind the heat shield and a Sun-viewing Faraday Cup are combined to ensure continuous and comprehensive sampling of the corona and wind throughout each encounter. Opportunities for coordinated observations with other spacecraft and ground-based observatories will be presented, along with a discussion of possible contributions from the theory and modeling communities, and from existing observations, as we prepare for this historic mission.

  8. Solar wind interaction with Venus and impact on its atmosphere

    NASA Astrophysics Data System (ADS)

    Barabash, S.; Futaana, Y.; Wieser, G. S.; Luhmann, J.

    2014-04-01

    We present a review of the solar wind interaction with Venus and how the interaction affects the Venusian atmosphere. The Venus Express observations for more than 8 years (2005-present) and quantitatively new simulation codes substantially advanced physical understanding of the plasma processes in the near-Venus space since the Pioneer Venus Orbiter (PVO) mission (1978-1992). The near-Venus space can be divided into several plasma domains: the magnetotail with the plasmasheet, induced magnetosphere, and magnetosheath. The bow shock separates the undisturbed solar wind from the Venus-affected environment. We review the shapes and positions of the boundaries enveloping the main domains and discuss how they are formed by the current systems and pressure balance. In particular, we discuss the morphology and dynamics of the near-Venus magnetotail that was not accessible by PVO. Using the unique Venus Express measurements we discuss the ion acceleration processes and their links to the ionosphere. The focus is given to the Venus' atmosphere erosion associated with the solar wind interaction, both through the energy (ion acceleration) and momentum (atmospheric sputtering) transfer. We review the measurements of the escape rates, their variability with the upstream solar wind conditions and the solar cycle. We emphasize the measurements duirng extreme solar wind conditions as an analogue with nominal conditions for the young Sun. The modeling efforts in this area are also reviewed as they provide a quantitatively approach to understand the impact of the solar wind interaction on the atmospheric evolution. Finally, we compare Venus with other planets of the terrestrial planet group, the Earth and Mars. The Earth, a twin planet of the similar size, is magnetized. Mars, an unmagnetized planet like Venus, possesses by far weaker gravitation to hold its atmospheric gasses. This comparative magnetosphere approach based on the natural solar system laboratory of experiments gives

  9. Solar wind H-3 and C-14 abundances and solar surface processes. [in lunar soil

    NASA Technical Reports Server (NTRS)

    Fireman, E. L.; Defelice, J.; Damico, J.

    1976-01-01

    Tritium is measured as a function of depth in a Surveyor 3 sample. The upper limit for solar-wind-implanted tritium gives an H-3/H-1 limit for the solar wind of 10 to the -11th power. The temperature-release patterns of C-14 from lunar soils are measured. The C-14 release pattern from surface soils differs from a trench-bottom soil and gives positive evidence for the presence of C-14 in the solar wind with a C-14/H-1 ratio of approximately 6 by 10 to the -11th power. This C-14 content fixes a minimal magnitude for nuclear processes on the solar surface averaged over the past 10,000 yr. The H-3 and C-14 contents combine to require that either the mixing rate above the photosphere be rapid or that the H-3 produced by nuclear reactions be destroyed by secondary nuclear reactions before escaping in the solar wind.

  10. Sources of the Slow Solar Wind During the Solar Cycle 23/24 Minimum

    NASA Astrophysics Data System (ADS)

    Kilpua, E. K. J.; Madjarska, M. S.; Karna, N.; Wiegelmann, T.; Farrugia, C.; Yu, W.; Andreeova, K.

    2016-10-01

    We investigate the characteristics and the sources of the slow ({<} 450 km s^{-1}) solar wind during the four years (2006 - 2009) of low solar activity between Solar Cycles 23 and 24. We used a comprehensive set of in-situ observations in the near-Earth solar wind ( Wind and ACE) and removed the periods when large-scale interplanetary coronal mass ejections were present. The investigated period features significant variations in the global coronal structure, including the frequent presence of low-latitude active regions in 2006 - 2007, long-lived low- and mid-latitude coronal holes in 2006 - mid-2008 and mostly the quiet Sun in 2009. We examined Carrington rotation averages of selected solar plasma, charge state, and compositional parameters and distributions of these parameters related to the quiet Sun, active region Sun, and the coronal hole Sun. While some of the investigated parameters ( e.g. speed, the C+6/C+4 and He/H ratios) show clear variations over our study period and with solar wind source type, some (Fe/O) exhibit very little changes. Our results highlight the difficulty of distinguishing between the slow solar wind sources based on the inspection of solar wind conditions.

  11. Ions with low charges in the solar wind as measured by SWICS on board Ulysses. [Solar Wind Ion Composition Spectrometer

    NASA Technical Reports Server (NTRS)

    Geiss, J.; Ogilvie, K. W.; Von Steiger, R.; Mall, U.; Gloeckler, G.; Galvin, A. B.; Ipavich, F.; Wilken, B.; Gliem, F.

    1992-01-01

    We present new data on rare ions in the solar wind. Using the Ulysses-SWICS instrument with its very low background we have searched for low-charge ions during a 6-d period of low-speed solar wind and established sensitive upper limits for many species. In the solar wind, we found He(1+)/He(2+) of less than 5 x 10 exp -4. This result and the charge state distributions of heavier elements indicate that all components of the investigated ion population went through a regular coronal expansion and experienced the typical electron temperatures of 1 to 2 million Kelvin. We argue that the virtual absence of low-charge ions demonstrates a very low level of nonsolar contamination in the source region of the solar wind sample we studied. Since this sample showed the FlP effect typical for low-speed solar wind, i.e., an enhancement in the abundances of elements with low first ionization potential, we conclude that this enhancement was caused by an ion-atom separation mechanism operating near the solar surface and not by foreign material in the corona.

  12. Chromospheric alfvenic waves strong enough to power the solar wind.

    PubMed

    De Pontieu, B; McIntosh, S W; Carlsson, M; Hansteen, V H; Tarbell, T D; Schrijver, C J; Title, A M; Shine, R A; Tsuneta, S; Katsukawa, Y; Ichimoto, K; Suematsu, Y; Shimizu, T; Nagata, S

    2007-12-07

    Alfvén waves have been invoked as a possible mechanism for the heating of the Sun's outer atmosphere, or corona, to millions of degrees and for the acceleration of the solar wind to hundreds of kilometers per second. However, Alfvén waves of sufficient strength have not been unambiguously observed in the solar atmosphere. We used images of high temporal and spatial resolution obtained with the Solar Optical Telescope onboard the Japanese Hinode satellite to reveal that the chromosphere, the region sandwiched between the solar surface and the corona, is permeated by Alfvén waves with strong amplitudes on the order of 10 to 25 kilometers per second and periods of 100 to 500 seconds. Estimates of the energy flux carried by these waves and comparisons with advanced radiative magnetohydrodynamic simulations indicate that such Alfvén waves are energetic enough to accelerate the solar wind and possibly to heat the quiet corona.

  13. On the history of the solar wind discovery

    NASA Astrophysics Data System (ADS)

    Obridko, V. N.; Vaisberg, O. L.

    2017-03-01

    The discovery of the solar wind has been an outstanding achievement in heliophysics and space physics. The solar wind plays a crucial role in the processes taking place in the Solar System. In recent decades, it has been recognized as the main factor that controls the terrestrial effects of space weather. The solar wind is an unusual plasma laboratory of giant scale with a fantastic diversity of parameters and operating modes, and devoid of influence from the walls of laboratory plasma systems. It is also the only kind of stellar wind accessible for direct study. The history of this discovery is quite dramatic. Like many remarkable discoveries, it had several predecessors. However, the honor of a discovery usually belongs to a scientist who was able to more fully explain the phenomenon. Such a man is deservedly considered the US theorist Eugene Parker, who discovered the solar wind, as we know it today, almost "with the point of his pen". In 2017, we will celebrate the 90th anniversary birthday of Eugene Parker.

  14. Direct evidence for kinetic effects associated with solar wind reconnection.

    PubMed

    Xu, Xiaojun; Wang, Yi; Wei, Fengsi; Feng, Xueshang; Deng, Xiaohua; Ma, Yonghui; Zhou, Meng; Pang, Ye; Wong, Hon-Cheng

    2015-01-28

    Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas. In-situ observations in the Earth's magnetosphere provide solid consistence with theoretical models on the point that kinetic effects are required in the collisionless reconnection. However, all the observations associated with solar wind reconnection have been analyzed in the context of magnetohydrodynamics (MHD) although a lot of solar wind reconnection exhausts have been reported. Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown. Here, by dual-spacecraft observations, we report a solar wind reconnection with clear Hall magnetic fields. Its corresponding Alfvenic electron outflow jet, derived from the decouple between ions and electrons, is identified, showing direct evidence for kinetic effects that dominate the collisionless reconnection. The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed.

  15. Coupling of the coronal helium abundance to the solar wind

    NASA Technical Reports Server (NTRS)

    Hansteen, Viggo H.; Leer, Egil; Holzer, Thomas E.

    1994-01-01

    Models of the transition region-corona-solar wind system are investigated in order to find the coronal helium abundance and to study the role played by coronal helium in controlling the solar wind proton flux. The thermal force on alpha-particles in the transition region sets the flow of helium into the corona. The frictional coupling between alpha-particles and protons and/or the electric polarization field determines the proton flux in the solar wind as well as the fate of the coronal helium content. The models are constructed by solving the time-dependent population and momentum equations for all species of hydrogen and helium in an atmosphere with a given temperature profile. Several temperature profiles are considered in order to very the roles of frictional coupling and electric polarization field in the solar wind, and the thermal force in the transition region. Steady-state solutions are found for coronae