Sample records for latitude-dependent solar wind

  1. Latitude dependence of long-term geomagnetic activity and its solar wind drivers

    NASA Astrophysics Data System (ADS)

    Myllys, M.; Partamies, N.; Juusola, L.

    2015-05-01

    To validate the usage of global indices in studies of geomagnetic activity, we have examined the latitude dependence of geomagnetic variations in Fennoscandia and Svalbard from 1994 to 2010. Daily standard deviation (SD) values of the horizontal magnetic field have been used as a measure of the ground magnetic disturbance level. We found that the timing of the geomagnetic minimum depends on the latitude region: corresponding to the minimum of sunspot cycle 22 (in 1996), the geomagnetic minimum occurred between the geomagnetic latitudes 57-61° in 1996 and at the latitudes 64-67° in 1997, which are the average auroral oval latitudes. During sunspot cycle 23, all latitude regions experienced the minimum in 2009, a year after the sunspot minimum. These timing differences are due to the latitude dependence of the 10 s daily SD on the different solar wind drivers. In the latitude region of 64-67°, the impact of the high-speed solar wind streams (HSSs) on the geomagnetic activity is the most pronounced compared to the other latitude groups, while in the latitude region of 57-61°, the importance of the coronal mass ejections (CMEs) dominates. The geomagnetic activity maxima during ascending solar cycle phases are typically caused by CME activity and occur especially in the oval and sub-auroral regions. The strongest geomagnetic activity occurs during the descending solar cycle phases due to a mixture of CME and HSS activity. Closer to the solar minimum, less severe geomagnetic activity is driven by HSSs and mainly visible in the poleward part of the auroral region. According to our study, however, the timing of the geomagnetic activity minima (and maxima) in different latitude bands is different, due to the relative importance of different solar wind drivers at different latitudes.

  2. Cosmic ray modulation with a Fisk-type heliospheric magnetic field and a latitude-dependent solar wind speed

    NASA Astrophysics Data System (ADS)

    Hitge, M.; Burger, R. A.

    2010-01-01

    The effect of a latitude-dependent solar wind speed on a Fisk heliospheric magnetic field [Fisk, L. A. Motion of the footpoints of heliospheric magnetic field lines at the Sun: implications for recurrent energetic particle events at high heliographic latitudes. J. Geophys. Res. 101, 15547-15553, 1996] was first discussed by Schwadron and Schwadron and McComas [Schwadron, N.A. An explanation for strongly underwound magnetic field in co-rotating rarefaction regions and its relationship to footpoint motion on the the sun. Geophys. Res. Lett. 29, 1-8, 2002. and Schwadron, N.A., McComas, D.J. Heliospheric “FALTS”: favored acceleration locations at the termination shock. Geophys. Res. Lett. 30, 41-1, 2003]. Burger and Sello [Burger, R.A., Sello, P.C. The effect on cosmic ray modulation of a Parker field modified by a latitudinal-dependent solar wind speed. Adv. Space Res. 35, 643-646, 2005] found a significant effect for a simplified 2D version of a latitude-dependent Fisk-type field while Miyake and Yanagita [Miyake, S., Yanagita, S. The effect of a modified Parker field on the modulation of the galactic cosmic rays. In: Proceedings of 30th International Cosmic Ray Conference. Merida, Mexico, vol. 1, 445-448, 2007] found a smaller effect. The current report improves on a previous attempt Hitge and Burger [Hitge, M., Burger, R.A. The effect of a latitude-dependent solar wind speed on cosmic-ray modulation in a Fisk-type heliospheric magnetic field. In: Proceedings of 30th International Cosmic Ray Conference. Merida, Mexico, vol. 1, pp. 449-450, 2007] where the global change in the solar wind speed and not the local speed gradient was emphasized. The sheared Fisk field of Schwadron and McComas [Schwadron, N.A., McComas, D.J. Heliospheric “FALTS”: Favored acceleration locations at the termination shock. Geophys. Res. Lett. 30, 41-1, 2003.) is similar to the current Schwadron-Parker hybrid field. Little difference is found between the effects of a Parker field and a Schwadron-Parker hybrid field on cosmic-ray modulation, in contrast to the results of Burger and Sello and Miyake and Yanagita [Burger, R.A., Sello, P.C. The effect on cosmic ray modulation of a Parker field modified by a latitudinal-dependent solar wind speed. Adv. Space Res. 35, 643-646, 2005 and Miyake, S., Yanagita, S. The effect of a modified Parker field on the modulation of the galactic cosmic rays. In: Proceedings of 30th International Cosmic Ray Conference. Merida, Mexico, vol. 1, pp. 445-448, 2007]. The two-dimensional approximation used by these authors is therefore inadequate to model the complexities of the actual three-dimensional field. We also show that a Fisk-type field with a latitude-dependent solar wind speed (Schwadron-Parker hybrid field) decreases both the relative amplitude of recurrent cosmic ray intensity variations and latitude gradients and yields similar constants of proportionality for these quantities as for the constant solar wind speed case.

  3. Latitude dependence of solar wind velocity observed > or approx. =1 AU

    SciTech Connect

    Mitchell, D.G.; Roelof, E.C.; Wolfe, J.H.

    1981-01-01

    The large-scale solar wind velocity structure in the outer heliosphere has been systematically analyzed for Carrington rotations 1587-1541 (March 1972 to April 1976). Spacecraft data were taken from Imp 7/8 at earth, Pioneer 6, 8, and 9 near 1AU, and Pioneer 10 and 11 between 1.6 and 5 AU. Using the constant radial velocity solar wind approximation to map all of the velocity data to its high coronal emission heliolongitude, we examined the velocity structure observed at different spacecraft for latitudinal dependence and compared it with coronal structure in soft X rays and Ha absorption features. The constant radial velocity approximation usually remains self-consistent in decreasing or constant velocity solar wind out to 5 AU, enabling us to separate radial from latitudinal propagation effects. We found several examples of sharp nonmeridional stream boundaries in interplanetary space (approx.5/sup 0/ latitude in width), often directly associated with features in coronal X rays and Ha. In one structure there is evidence for significant (up to 40/sup 0/) nonradial flow of the plasma in the corona below the altitude of transition to super-Alfvenic flow.

  4. Is the solar spectrum latitude dependent? An investigation with SST/TRIPPEL

    E-print Network

    Kiselman, Dan; Gustafsson, Bengt; Asplund, Martin; Meléndez, Jorge; Scharmer, Göran B; Langhans, Kai

    2011-01-01

    Context: In studies of the solar spectrum relative to spectra of solar twin stars, it has been found that the chemical composition of the Sun seems to depart systematically from those of the twins. One possible explanation is that the effect is due to the special aspect angle of the Sun when observed from Earth, as compared with the aspect angles of the twins. Thus, a latitude dependence of the solar spectrum, even with the heliocentric angle constant, could lead to effects of the type observed. Aim: We explore a possible variation in the strength of certain spectral lines, used in the comparisons between the composition of the Sun and the twins, at loci on the solar disk with different latitudes but at constant heliocentric angle. Methods: We use the TRIPPEL spectrograph at the Swedish 1-m Solar Telescope on La Palma to record spectra in five spectral regions in order to compare different locations on the solar disk at a heliocentric angle of 45 deg. Equivalent widths and other parameters are measured for fi...

  5. The qWR star HD 45166. II. Fundamental stellar parameters and evidence of a latitude-dependent wind

    E-print Network

    J. H. Groh; A. S. Oliveira; J. E. Steiner

    2008-04-10

    The enigmatic object HD 45166 is a qWR star in a binary system with an orbital period of 1.596 day, and presents a rich emission-line spectrum in addition to absorption lines from the companion star (B7 V). As the system inclination is very small (i=0.77 +- 0.09 deg), HD 45166 is an ideal laboratory for wind-structure studies. The goal of the present paper is to determine the fundamental stellar and wind parameters of the qWR star. A radiative transfer model for the wind and photosphere of the qWR star was calculated using the non-LTE code CMFGEN. The wind asymmetry was also analyzed using a recently-developed version of CMFGEN to compute the emerging spectrum in two-dimensional geometry. The temporal-variance spectrum (TVS) was calculated for studying the line-profile variations. Abundances, stellar and wind parameters of the qWR star were obtained. The qWR star has an effective temperature of Teff=50000 +- 2000 K, a luminosity of log(L/Lsun)=3.75 +- 0.08, and a corresponding photospheric radius of Rphot=1.00 Rsun. The star is helium-rich (N(H)/N(He) = 2.0), while the CNO abundances are anomalous when compared either to solar values, to planetary nebulae, or to WR stars. The mass-loss rate is Mdot = 2.2 . 10^{-7} Msun/yr, and the wind terminal velocity is vinf=425 km/s. The comparison between the observed line profiles and models computed under different latitude-dependent wind densities strongly suggests the presence of an oblate wind density enhancement, with a density contrast of at least 8:1 from equator to pole. If a high velocity polar wind is present (~1200 km/s), the minimum density contrast is reduced to 4:1. The wind parameters determined are unusual when compared to O-type stars or to typical WR stars. (abridged)

  6. Time trends and latitude dependence of uveal and cutaneous malignant melanoma induced by solar radiation

    SciTech Connect

    Moan, J.; Setlow, R.; Cicarma, E.; Porojnicu, A. C.; Grant, W. B.; Juzeniene, A.

    2010-01-01

    In order to evaluate the role of solar radiation in uveal melanoma etiology, the time and latitude dependency of the incidence rates of this melanoma type were studied in comparison with those of cutaneous malignant melanoma (CMM). Norway and several other countries with Caucasian populations were included. There is a marked north - south gradient of the incidence rates of CMM in Norway, with three times higher rates in the south than in the north. No such gradient is found for uveal melanoma. Similar findings have been published for CMM in other Caucasian populations, with the exception of Europe as a whole. In most populations the ratios of uveal melanoma incidence rates to those of CMM tend to decrease with increasing CMM rates. This is also true for Europe, in spite of the fact that in this region there is an inverse latitude gradient of CMM, with higher rates in the north than in the south. In Norway the incidence rates of CMM have increased until about 1990 but have been constant, or even decreased (for young people) after that time, indicating constant or decreasing sun exposure. The uveal melanoma rates have been increasing after 1990. In most other populations the incidence rates of CMM have been increasing until recently while those of uveal melanoma have been decreasing. These data generally support the assumption that uveal melanomas are not generated by ultraviolet (UV) radiation and that solar UV, via its role in vitamin D photosynthesis, may have a protective effect.

  7. 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.

  8. The Solar Wind

    NSDL National Science Digital Library

    David Hathaway

    This site describes the nature of the solar winds and the relationships between its speed and solar features. The effect of the variations in the speed of the solar wind on the magnetosphere of the Earth is also discussed, along with the research results of the Ulysses spacecraft and the Advanced Composition Explorer (ACE) satellite. The site also provides links to solar wind conditions for the last seven days and the last 24 hours.

  9. Warming: mechanism and latitude dependence

    NASA Astrophysics Data System (ADS)

    Barkin, Yury

    2010-05-01

    Introduction. In the work it is shown, that in present warming of climate of the Earth and in style of its display a fundamental role the mechanism of the forced swing and relative oscillations of eccentric core of the Earth and its mantle plays. Relative displacements of the centers of mass of the core and the mantle are dictated by the features of orbital motions of bodies of solar system and nonineriality of the Earth reference frame (or ot the mantle) at the motion of the Earth with respect to a baricenter of solar system and at rotation of the planet. As a result in relative translational displacements of the core and the mantle the frequencies characteristic for orbital motion of all bodies of solar system, and also their combination are shown. Methods of a space geodesy, gravimetry, geophysics, etc. unequivocally and clearly confirm phenomenon of drift of the center of mass of the Earth in define northern direction. This drift is characterized by the significant velocity in about 5 mm/yr. The unique opportunity of its explanation consists in the natural assumption of existence of the unidirectional relative displacement (drift) the center of mass of the core and the center of mass of the mantle of the Earth. And this displacement (at superfluous mass of the core in 16.7 % from the mass of full the Earth) is characterized still more significant velocity in 2.6 cm/yr and occurs on our geodynamic studies in a direction to Taimyr peninsula. The dynamic explanation to century drift for today does not exist. It is possible to note, however, that data of observations of last years, indirectly testifying that similar drifts of the centers of mass in present epoch occur on other bodies of Solar system have been obtain: the Sun, Mars, the Titan, Enceladus, the Neptune, etc. We connect with mentioned phenomena the observed secular variations of natural processes on this celestial bodies. I.e. it is possible to assume, that observable eccentric positions of the centers of mass of some bodies of solar system and attributes of secular displacements of their centers of mass are universal and testify to relative translational displacements of shells of these bodies (such as the core, the mantle and others). And it means, that there is a highly effective mechanism of an active life of planets and satellites [1, 2]. This mechanism is distinct from the tidal mechanism of gravitational interaction of deformable celestial bodies. Its action is shown, for example, even in case if the core and the mantle are considered as absolutely rigid gravitating bodies, but separated by a is viscous-elastic layer. Classics of celestial mechanics did not consider gravitational interaction and relative translational displacement of the core and the mantle of the Earth. As our studies have shown the specified new mechanism is high energetic and allows to explain many of the phenomena earlier inaccessible to understanding in various geosciences, including climatology [1] - [5]. It has been shown, that secular changes in activity of all planetary processes on the Earth are connected with a secular drift of the core of the Earth, and are controlled by the core and are reflections and displays of the core drift [5]. It is naturally, that slow climatic changes are connected with drift of the core, with induced by this drift inversion changes in an atmosphere, ocean, with thermodynamic variations of state of layer D ', with changes and variations in mantle convection and in plume activity of the Earth. The drift of the core controls a transmission of heat in the top layers of the mantle and on a surface of the Earth, organizes volcanic and seismic activity of the Earth in planetary scale. The mechanism of a warming up of layers of the mantle and cyclic inversion changes of a climate. According to a developed geodynamic model all layers of the mantle at oscillations and motions of the core under action of its gravitational attraction test wide class of inversion deformations [1]. Thus the part of energy of deformations passes in heat by virtue of dissipation

  10. Solar cycle and latitude dependence of high-beta suprathermal plasma conditions in interplanetary space between 1.3 and 5.4 AU

    NASA Astrophysics Data System (ADS)

    Marhavilas, Panagiotis K.

    2012-05-01

    The analysis of energetic particles and magnetic field measurements from the Ulysses spacecraft has shown that in a series of events, the energy density contained in the suprathermal tail particle distribution is comparable to or larger than that of the magnetic field, creating conditions of high-beta plasma. In this work we analyze periods of high-beta suprathermal plasma occurrences (?ep > 1) in interplanetary space, using the ratio (?ep) of the energetic particle (20 keV to ˜5 MeV) and magnetic field energy densities from measurements covering the entire Ulysses mission lifetime (1990-2009) in order to reveal new or to reconfirm some recently defined interesting characteristics. The main key-results of the work are summarized as follows: (i) we verify that high-beta events are detected within well identified regions corresponding mainly to the vicinity of shock surfaces and magnetic structures, and associated with energetic particle intensity enhancements due to (a) reacceleration at shock-fronts and (b) unusually large magnetic field depressions. (ii) We define three considerable features for the high-beta events, concentrated on the next points: (a) there is an appreciable solar-activity influence on the high-beta events, during the maximum and middle solar-cycle phase, (b) the annual peak magnitude and the number of occurrences of high events are well correlated with the sunspot number, (c) the high-beta suprathermal plasma events present a spatial distribution in heliographic latitudes (HL) up to ˜±80°, and a specific important concentration on the low (-25° ? HL < -6°, 6° < HL ? 25°) and median (-45° ? HL < -25°, 25° < HL ? 45°) latitudes. We also reconfirm by a statistical analysis the results of Marhavilas and Sarris (2011), that the high-beta suprathermal plasma (?ep > 1) events are characterized by a very large parameter ?ep (up to 1732.5), a great total duration (406 days) and a large percentage of the Ulysses-mission lifetime (which is equal to 6.34% of the total duration with usable measurements, and 11.3% of the duration in presence of suprathermal particles events).

  11. Solar wind composition

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Coplan, M. A.

    1995-01-01

    Advances in instrumentation have resulted in the determination of the average abundances of He, C, N, O, Ne, Mg, Si, S, and Fe in the solar wind to approximately 10%. Comparisons with solar energetic particle (SEP) abundances and galactic cosmic ray abundances have revealed many similarities, especially when compared with solar photospheric abundances. It is now well established that fractionation in the corona results in an overabundance (with respect to the photosphere) of elements with first ionization potentials less than 10 eV. These observations have in turn led to the development of fractionation models that are reasonably successful in reproducing the first ionization (FIP) effect. Under some circumstances it has been possible to relate solar wind observations to particular source regions in the corona. The magnetic topologies of the source regions appear to have a strong influence on the fractionation of elements. Comparisons with spectroscopic data are particularly useful in classifying the different topologies. Ions produced from interstellar neutral atoms are also found in the solar wind. These ions are picked up by the solar wind after ionization by solar radiation or charge exchange and can be identified by their velocity in the solar wind. The pick-up ions provide most of the pressure in the interplanetary medium at large distances. Interstellar abundances can be derived from the observed fluxes of solar wind pick-up ions.

  12. SOLAR WIND CORRELATIONS: USING A SOLAR WIND MONITOR SUCCESSFULLY

    E-print Network

    Richardson, John

    SOLAR WIND CORRELATIONS: USING A SOLAR WIND MONITOR SUCCESSFULLY K.I. PAULARENA AND J.D. RICHARDSON.N. ZASTENKER AND P.A. DALIN Space Research Institute, RAS, Moscow, Russia Abstract. Solar wind plasma to which distant solar wind plasma measurements (such as those from near Earth's L1 point) represent

  13. 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.

  14. 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.

  15. 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.

  16. Solar wind stream interfaces

    Microsoft Academic Search

    J. T. Gosling; J. R. Asbridge; S. J. Bame; W. C. Feldman

    1978-01-01

    Measurements aboard Imp 6, 7, and 8 reveal that approximately one third of all high-speed solar wind streams observed at 1 AU contain a sharp boundary (of thickness less than approx.4 x 10⁴ km) near their leading edge, called a stream interface, which separates plasma of distinctly different properties and origins. Identified as discontinuities across which the density drops abruptly,

  17. Solar Wind Electrons

    Microsoft Academic Search

    W. C. Feldman; J. R. Asbridge; S. J. Bame; M. D. Montgomery; S. P. Gary

    1975-01-01

    Average characteristics of solar wind electron velocity distributions as well as the range and nature of their variations are presented. The measured distributions are generally symmetric about the heat flux direction and are adequately parameterized by the superposition of a nearly bi-Maxwellian function which characterizes the low-energy electrons and a bi-Maxwellian function which characterizes a distinct, ubiquitous component of higher-energy

  18. Discontinuities in the solar wind

    Microsoft Academic Search

    D. S. Colburn; C. P. Sonett

    1966-01-01

    The nonuniform emission of the solar wind from the sun means that conditions are established which favor the development of discontinuities in the plasma parameters. Since the solar wind is in rapid proper motion with respect to the sun and the earth, examination of these discontinuities requires that the wind velocity be transformed away. Then it is found that they

  19. Petrovay: Solar physics Solar wind and heliosphere THE SOLAR WIND AND THE HELIOSPHERE

    E-print Network

    Petrovay, Kristóf

    Petrovay: Solar physics Solar wind and heliosphere THE SOLAR WIND AND THE HELIOSPHERE 1951: First proposal of solar corpuscular radiation by Biermann, to explain slight deviation of comets' ion tails from radial (aberration effect). 1958: Parker's supersonic wind model 1962: Mariner-2 detects solar wind. v

  20. Four Kinds of Solar Wind

    Microsoft Academic Search

    W. I. Axford

    2004-01-01

    It is customary to divide the solar wind seen during sunspot minimum in distinct fast and slow regimes. Most theoretical modelling has been concerned with the fast wind since the slow wind is evidently inherently transient, associated with the opening and closing of magnetic field lines associated with quiet coronal streamers. The fast wind, associated with polar coronal holes above

  1. Solar Wind and its Evolution

    E-print Network

    Suzuki, Takeru K

    2011-01-01

    By using our previous results of magnetohydrodynamical simulations for the solar wind from open flux tubes, I discuss how the solar wind in the past is different from the current solar wind. The simulations are performed in fixed one-dimensional super-radially open magnetic flux tubes by inputing various types of fluctuations from the photosphere, which automatically determines solar wind properties in a forward manner. The three important parameters which determine physical properties of the solar wind are surface fluctuation, magnetic field strengths, and the configuration of magnetic flux tubes. Adjusting these parameters to the sun at earlier times in a qualitative sense, I infer that the quasi-steady-state component of the solar wind in the past was denser and slightly slower if the effect of the magneto-centrifugal force is not significant. I also discuss effects of magneto-centrifugal force and roles of coronal mass ejections.

  2. Latitude dependence of narrow bipolar pulse emissions

    NASA Astrophysics Data System (ADS)

    Ahmad, M. R.; Esa, M. R. M.; Cooray, V.; Baharudin, Z. A.; Hettiarachchi, P.

    2015-06-01

    In this paper, we present a comparative study on the occurrence of narrow bipolar pulses (NBPs) and other forms of lightning flashes across various geographical areas ranging from northern regions to the tropics. As the latitude decreased from Uppsala, Sweden (59.8°N) to South Malaysia (1.5°N), the percentage of NBP emissions relative to the total number of lightning flashes increased significantly from 0.13% to 12%. Occurrences of positive NBPs were more common than negative NBPs at all observed latitudes. However, as latitudes decreased, the negative NBP emissions increased significantly from 20% (Uppsala, Sweden) to 45% (South Malaysia). Factors involving mixed-phase region elevations and vertical extents of thundercloud tops are invoked to explain the observed results. These factors are fundamentally latitude dependent. Our results suggest that the NBP emission rate is not a useful measure to monitor thunderstorm severity because regular tropical thunderstorms, where relatively high NBP emissions occur, lack suitable conditions to become severe (i.e., there is modest convective available potential energy and a lack of baroclinity in such regions). Observations of significantly high negative NBP occurrences together with very rare occurrences of positive cloud-to-ground flashes and isolated breakdown pulses in tropical thunderstorms are indicative of a stronger negative screening layer magnitude and weaker lower positive charge region magnitude than those in northern regions.

  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

    ...EL12-109-000] Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind Lessee, LLC; Pacific Wind 2, LLC...planned capacity of the Petitioners' wind and solar generation projects to the...

  4. New Horizons Solar Wind Around Pluto (SWAP) Solar Wind Measurements

    NASA Astrophysics Data System (ADS)

    Elliott, H. A.; McComas, D. J.; Mukherjee, J.; Valek, P. W.; Livadiotis, G.; Delamere, P. A.; Bagenal, F.; Nicolaou, G.

    2013-12-01

    The Solar Wind Around Pluto (SWAP) instrument on the New Horizons (NH) spacecraft has measured the solar wind from 5 to 27 AU. Optimization of the SWAP instrument design for the NH Pluto/Charon flyby mission requirements, adds complexity to the analysis of the measurements. In this presentation we describe key aspects of the instrument calibration necessary to obtain accurate solar wind parameters. In the SWAP instrument, ions from the full field-of-view (10 by 276°) are focused onto a pair of coincidence Channel Electron Multipliers (CEMs). The instrument sensitivity varies across the FOV, and the energy and range of energies observed depends on the angle at which the ions enter. We developed a simple analytic expression for the count rates, which neglects such angle dependences, but runs quickly. Recently we developed a more comprehensive model that runs slower, but reproduces the spin variation due to the angle dependences in the instrument response. In the recent NH-SWAP observations, there are long intervals of very steady solar wind speeds. This is consistent with many solar wind structures becoming worn down with increasing distance as different speed parcels dynamically interact. In the steady solar wind speed intervals, we will examine the temperature to assess if the temperature shows signs of prior dynamic interaction between fast and slow wind streams as the wind parcels traversed distances greater than 20 AU. It could be that the temperature shows a regular alternating pattern of hotter and cooler wind. Although much of the recent solar wind observations are steady, at ~23.8 AU the SWAP measurements indicate a clear rarefaction with a decreasing speed profile followed by an increase in the speed forming a wave or shock. We compare this wave/shock event to the neighboring steady solar wind speed intervals.

  5. Solar wind and magnetosphere interactions

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Allen, J. H.; Cauffman, D. P.; Feynman, J.; Greenstadt, E. W.; Holzer, R. E.; Kaye, S. M.; Slavin, J. A.; Manka, R. H.; Rostoker, G.

    1979-01-01

    The relationship between the magnetosphere and the solar wind is addressed. It is noted that this interface determines how much of the solar plasma and field energy is transferred to the Earth's environment, and that this coupling not only varies in time, responding to major solar disturbances, but also to small changes in solar wind conditions and interplanetary field directions. It is recommended that the conditions of the solar wind and interplanetary medium be continuously monitored, as well as the state of the magnetosphere. Other recommendations include further study of the geomagnetic tail, tests of Pc 3,4 magnetic pulsations as diagnostics of the solar wind, and tests of kilometric radiation as a remote monitor of the auroral electrojet.

  6. Solar wind composition. Progress report

    SciTech Connect

    Ogilvie, K.W.; Coplan, M.A.

    1995-01-01

    Advances in instrumentation have resulted in the determination of the average abundances of He, C, N, O, Ne, Mg, Si, S, and Fe in the solar wind to approximately 10%. Comparisons with solar energetic particle (SEP) abundances and galactic cosmic ray abundances have revealed many similarities, especially when compared with solar photospheric abundances. It is now well established that fractionation in the corona results in an overabundance (with respect to the photosphere) of elements with first ionization potentials less than 10 eV. These observations have in turn led to the development of fractionation models that are reasonably successful in reproducing the first ionization (FIP) effect. Under some circumstances it has been possible to relate solar wind observations to particular source regions in the corona. The magnetic topologies of the source regions appear to have a strong influence on the fractionation of elements. Comparisons with spectroscopic data are particularly useful in classifying the different topologies. Ions produced from interstellar neutral atoms are also found in the solar wind. These ions are picked up by the solar wind after ionization by solar radiation or charge exchange and can be identified by their velocity in the solar wind. The pick-up ions provide most of the pressure in the interplanetary medium at large distances. Interstellar abundances can be derived from the observed fluxes of solar wind pick-up ions.

  7. Forecasting Solar Wind Speeds

    E-print Network

    Suzuki, T K

    2006-01-01

    By explicitly taking into account effects of Alfven waves, I derive from a simple energetics argument a fundamental relation which predicts solar wind (SW) speeds in the vicinity of the earth from physical properties on the sun. Kojima et al. recently found from their observations that a ratio of surface magnetic field strength to an 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 an evidence of the Alfven wave which accelerates SW in expanding flux tubes. The observations further require that fluctuation amplitudes of magnetic field lines at the surface should be almost universal in different coronal holes, which needs to be tested by future observations.

  8. Measuring the Turbulent Solar Wind

    NASA Astrophysics Data System (ADS)

    DeForest, Craig; Matthaeus, William; Howard, Tim

    2015-04-01

    The slow solar wind is turbulent, a fact that may explain the variability of the slow wind at Earth. But the nature and strength of the turbulence has been hard to quantify because measurements have been limited to in-situ detection of variations in measurable parameters. Remote imaging of comet tails offers a unique opportunity to study the paths of localized "test particles" in the solar wind, and to analyze the motion in the same way that hydrodynamicists might study turbulence in water with test particles. We report on a careful analysis of the motion of 230 individually tracked features in the tail of a comet observed with STEREO/HI-1, which interacted strongly with the solar wind between 0.2 and 0.3 AU during the observation period, and draw deep conclusions about the nature of solar wind variability.

  9. Wind and Solar Curtailment: Preprint

    SciTech Connect

    Lew, D.; Bird, L.; Milligan, M.; Speer, B.; Wang, X.; Carlini, E. M.; Estanqueiro, A.; Flynn, D.; Gomez-Lazaro, E.; Menemenlis, N.; Orths, A.; Pineda, I.; Smith, J. C.; Soder, L.; Sorensen, P.; Altiparmakis, A.; Yoh, Y.

    2013-09-01

    High penetrations of wind and solar generation on power systems are resulting in increasing curtailment. Wind and solar integration studies predict increased curtailment as penetration levels grow. This paper examines experiences with curtailment on bulk power systems internationally. It discusses how much curtailment is occurring, how it is occurring, why it is occurring, and what is being done to reduce curtailment. This summary is produced as part of the International Energy Agency Wind Task 25 on Design and Operation of Power Systems with Large Amounts of Wind Power.

  10. A polytropic model for the solar wind

    Microsoft Academic Search

    C. Jacobs; S. Poedts

    2011-01-01

    The solar wind fills the heliosphere and is the background medium in which coronal mass ejections propagate. A realistic modelling of the solar wind is therefore essential for space weather research and for reliable predictions. Although the solar wind is highly anisotropic, magnetohydrodynamic (MHD) models are able to reproduce the global, average solar wind characteristics rather well. The modern computer

  11. Magnetospheric feedback in solar wind energy transfer

    Microsoft Academic Search

    M. Palmroth; H. E. J. Koskinen; T. I. Pulkkinen; P. K. Toivanen; P. Janhunen; S. E. Milan; M. Lester

    2010-01-01

    The solar wind kinetic energy fueling all dynamical processes within the near-Earth space is extracted in a dynamo process at the magnetopause. This direct energy transfer from the solar wind into the magnetosphere depends on the orientation of the interplanetary magnetic field (IMF) as well as other solar wind parameters, such as the IMF magnitude and solar wind velocity. Using

  12. Solar wind plasma controlling magnetospheric coupling efficiency

    Microsoft Academic Search

    T. I. Pulkkinen; M. Palmroth; K. Andreeova; T. V. Laitinen; R. L. McPherron

    2008-01-01

    A wealth of new observational evidence add to the earlier understanding of solar wind - magnetosphere coupling the importance of solar wind speed and density. Statistical analysis shows that for the same electric field, events with higher solar wind speed cause larger AE disturbance than those with lower speed and higher magnetic field. Analysis of abrupt solar wind density changes

  13. 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.

  14. STATIONARITY IN SOLAR WIND FLOWS

    SciTech Connect

    Perri, S.; Balogh, A., E-mail: silvia.perri@issibern.c, E-mail: a.balogh@imperial.ac.u [International Space Science Institute, Hallerstrasse 6, Bern CH-3012 (Switzerland)

    2010-05-01

    By using single-point measurements in space physics it is possible to study a phenomenon only as a function of time. This means that we cannot have direct access to information about spatial variations of a measured quantity. However, the investigation of the properties of turbulence and of related phenomena in the solar wind widely makes use of an approximation frequently adopted in hydrodynamics under certain conditions, the so-called Taylor hypothesis; indeed, the solar wind flow has a bulk velocity along the radial direction which is much higher than the velocity of a single turbulent eddy embedded in the main flow. This implies that the time of evolution of the turbulent features is longer than the transit time of the flow through the spacecraft position, so that the turbulent field can be considered frozen into the solar wind flow. This assumption allows one to easily associate time variations with spatial variations and stationarity to homogeneity. We have investigated, applying criteria for weak stationarity to Ulysses magnetic field data in different solar wind regimes, at which timescale and under which conditions the hypothesis of stationarity, and then of homogeneity, of turbulence in the solar wind is well justified. We extend the conclusions of previous studies by Matthaeus and Goldstein to different parameter ranges in the solar wind. We conclude that the stationarity assumption in the inertial range of turbulence on timescales of 10 minutes to 1 day is reasonably satisfied in fast and uniform solar wind flows, but that in mixed, interacting fast, and slow solar wind streams the assumption is frequently only marginally valid.

  15. Latitude-Dependent Sensitivity to Stationary Perturbations in Simple Climate Models.

    NASA Astrophysics Data System (ADS)

    Salmun, H.; Cahalan, R. F.; North, G. R.

    1980-08-01

    The steady-state zonally averaged climate is perturbed by adding a latitude-dependent heat source to an energy balance equation of the simplified Budyko-Sellers type. The latitude of the ice edge, which is attached to an isotherm, becomes dependent on the strength of the perturbation. This dependence is given in terms of the well-known iceline-solar constant relation, and the latitude dependence of the perturbed temperature field is then uniquely determined. The exact analytical solution is linearized and expressed in terms of a superposition of line sources at various latitudes. The main features are. 1) The total temperature response is a sum of the direct effect of the perturbation and an indirect ice-albedo effect proportional to the solar ice-edge sensitivity; and 2) the indirect feedback effect produces an enhanced response in polar latitudes.

  16. Solar wind-magnetosphere coupling

    NASA Astrophysics Data System (ADS)

    Kamide, Y.; Slavin, J.

    An AGU Chapman Conference on Solar Wind-Magnetosphere Coupling was held at the Jet Propulsion Laboratory (JPL) of the California Institute of Technology, Pasadena, February 12-15, 1985. There were 95 scientific papers presented at the meeting, and 135 participants were registered.The interaction between the solar wind and the earth's magnetic field creates a large magnetic cavity that is termed the magnetosphere. Energy derived from the solar wind and subsequently transferred to the inner magnetosphere is the primary source of various dynamic processes in the magnetosphere and also of many interesting phenomena observable from the earth's surface, such as magnetic and auroral substorms. The purpose of this conference was to bring together scientists from all areas of solar terrestrial physics, both theoretical and experimental, to promote the study of “coupling” among the different regions of the geosphere.

  17. Solar wind theory and modelling

    NASA Technical Reports Server (NTRS)

    Hansteen, Viggo H.

    1995-01-01

    The outflow of coronal plasma into interplanetary space is a consequence of the coronal heating process. Therefore the formation of the corona and the acceleration of the solar wind should be treated as a single problem. Traditionally the mass or particle flux emanating from the extended corona has been thought of as being determined by the coronal temperature or scale height and the coronal (base) density. This argument follows from considerations of the momentum balance of the corona-wind system from which one obtains models of a close to hydrostatic corona out to the critical point where the flow becomes supersonic. With this approach to the acceleration of the wind is has been difficult to reconcile the relatively small variation observed in the proton flux at 1 AU with the predicted exponential dependence of the proton flux on the coronal temperature. In this talk we would like to emphasize another approach in which coronal energetics play the primary role. The deposition of energy into the corona through some 'mechanical' energy flux is balanced by the various energy sinks available to the corona and the sum of these processes determine the coronal structure, i.e. its temperature and density. The corona loses energy through heat conduction into the transition region, through radiative losses, and through the gravitational potential energy and kinetic energy put into the solar wind itself. We will show from a series of models of the chromosphere transition region-corona-solar wind system that most of the energy deposited in a magnetically open region will go into the solar wind, with roughly half going into kinetic energy and half into lifting the plasma out of the solar gravity field. The coronal base density will adjust itself in such a way that the heat conductive flux flowing into the transition region is radiated away in the upper chromosphere. The coronal temperature is set by the requirements that most of the deposited energy goes into accelerating the solar wind; the coronal scale height will adjust itself so that the solar wind energy losses conform to the amplitude of the input energy. These processes are modified by the 'mode' of energy deposition, and we will show the effects on coronal structure of changing the parameters describing coronal heating as well as the effects of including a helium fluid in the models. However, the location, scale height and/or form of the energy deposition (i.e. heating or direct acceleration) are not too important for the solar wind, the coronal density and temperature structure will vary with the 'mode' of energy deposition, but the solar wind mass flux depends mainly on the amplitude of the energy flux.

  18. Mars and the Solar Wind

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This artist's rendition depicts the response of the solar wind to the obstacle - the planet Mars - in it's path. A supersonic 'solar wind' consisting of electrically charged particles (ions and electrons) streams off the Sun into space. It is slowed to subsonic speeds in the vicinity of Mars at a parabolic surface called a 'bow shock' upstream of the planet. Here, the magnetic field fluctuates wildly and the flow of the solar wind becomes chaotic. Part of the orbital trajectory of the Mars Global Surveyor is indicated, with MGS approaching the planet just prior to over-flight of the pole.

    The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. JPL is an operating division of California Institute of Technology (Caltech).

  19. Wind in the Solar System

    NASA Astrophysics Data System (ADS)

    McIntosh, Gordon

    2010-02-01

    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 frost1 and precipitation.2 The present article is on winds in the solar system. A windy day or storm might motivate the inclusion of this subject into a lecture.

  20. Solar wind electron density and temperature over solar cycle 23: Thermal noise measurements on Wind

    E-print Network

    California at Berkeley, University of

    Solar wind electron density and temperature over solar cycle 23: Thermal noise measurements on Wind; received in revised form 6 April 2005; accepted 25 April 2005 Abstract We present the solar wind plasma parameters obtained from the Wind spacecraft during more than nine years, encompassing almost the whole solar

  1. Turbulence of the Solar Wind Studies of the Solar Wind Using the ACE and Helios Spacecraft

    E-print Network

    Turbulence of the Solar Wind Studies of the Solar Wind Using the ACE and Helios Spacecraft Bejamin;Abstract The solar wind is a supersonic ow of plasma emanating from the sun and traveling through the interplanetary medium to the outermost reaches of the heliosphere. The solar wind experiences in situ

  2. The Heating & Acceleration of the Solar Wind

    E-print Network

    Wurtele, Jonathan

    The Heating & Acceleration of the Solar Wind Eliot Quataert (UC Berkeley) Collaborators: Steve #12;Background · Heating required to accelerate the solar wind · Early models invoked e- conduction requires oppositely directed waves · solar wind: inward propagating waves generated by reflection of long

  3. Compressibility of solar wind Bogdan A. Hnat

    E-print Network

    Sengun, Mehmet Haluk

    Compressibility of solar wind turbulence Bogdan A. Hnat Centre for Fusion, Space and Astrophysics Collaborators: S. C. Chapman, K. Kiyani and G. Rowlands #12;Introduction Solar wind modeled by incompressible MHD (supported by observations in the fast solar wind [1]) Generation of compressive modes from

  4. THE SOLAR WIND PLASMA Dr. Joe Borovsky

    E-print Network

    Shyy, Wei

    THE SOLAR WIND PLASMA Dr. Joe Borovsky Los Alamos National Laboratory and University of Michigan Wednesday, 19 October 2011 4:00 pm Room 1005 EECS Building Abstract The solar wind is a large bumps and wiggles at all timescales. A difficulty in characterizing the solar wind from the time

  5. Coronal Heating and Solar Wind Energy Balance

    Microsoft Academic Search

    Ornulf Sandbaek; Egil Leer

    1995-01-01

    In this paper we present a parameter study of a two-fluid and a one-fluid model of the solar wind where coronal heating and solar wind acceleration is treated as one problem. To study the energy balance in the corona\\/solar wind system, we consider a \\

  6. Western Wind and Solar Integration Study

    Microsoft Academic Search

    D. Lew; R. Piwko; G. Jordan; N. Miller; K. Clark; L. Freeman; M. Milligan

    2011-01-01

    The Western Wind and Solar Integration Study (WWSIS) is one of the largest regional wind and solar integration studies to date. It was initiated in 2007 to examine the operational impact of up to 35% energy penetration of wind, photovoltaics (PV), and concentrating solar power (CSP) on the power system operated by the WestConnect group of utilities in Arizona, Colorado,

  7. 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.

  8. 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.

  9. Coronal holes as sources of solar wind

    Microsoft Academic Search

    J. T. Nolte; A. S. Krieger; A. F. Timothy; R. E. Gold; E. C. Roelof; G. Vaiana; A. J. Lazarus; J. D. Sullivan; P. S. McIntosh

    1976-01-01

    We investigate the association of high-speed solar wind with coronal holes during the Skylab mission by: (1) direct comparison of solar wind and coronal X-ray data; (2) comparison of near-equatorial coronal hole area with maximum solar wind velocity in the associated streams; and (3) examination of the correlation between solar and interplanetary magnetic polarities. We find that all large near-equatorial

  10. On the Solar-Wind/Magnetosphere Interaction

    NASA Astrophysics Data System (ADS)

    Borovsky, J. E.; Denton, M.

    2012-12-01

    We would like to address a number of points about the solar wind's interaction with the Earth's magnetosphere. (1) There are two aspects to the solar-wind driving of convection in the magnetosphere: reconnection (connecting the generator) and the solar-wind MHD generator. Most effort focuses on reconnection and ignores the physics of the generator. (2) Solar-wind coupling functions, and why the solar-wind electric field works so well. (3) The role of solar-wind density: feeding the magnetosphere. (4) Mach-number effects. (5) CME storms and CIR storms and why they differ. (6) The difference between storms driven by helmet-streamer CIRs and storms driven by pseudostreamer CIRs. (7) Some things we don't understand: the viscous interaction, the role of on-off driving, and the importance of wind shear.

  11. MAGNETOHYDRODYNAMIC SIMULATIONS OF THE SOLAR CORONA AND SOLAR WIND USING A BOUNDARY TREATMENT TO LIMIT SOLAR WIND MASS FLUX

    E-print Network

    California at Berkeley, University of

    MAGNETOHYDRODYNAMIC SIMULATIONS OF THE SOLAR CORONA AND SOLAR WIND USING A BOUNDARY TREATMENT TO LIMIT SOLAR WIND MASS FLUX Keiji Hayashi W. W. Hansen Experimental Physics Laboratory, Stanford ABSTRACT Magnetohydrodynamic simulations of the solar corona and solar wind are sensitive to conditions

  12. Solar-wind energy conversion system

    Microsoft Academic Search

    1982-01-01

    A combined solar-wind energy conversion system in which the combined effects of solar and wind energy are utilized in raising water from a lower to an upper water storage tank to increase its potential energy for generation of electricity. Incoming solar energy heats water to form steam which is temporarily stored. The stored steam is vented to one of first

  13. Solar wind-magnetosphere energy coupling

    Microsoft Academic Search

    S.-I. Akasofu

    1983-01-01

    It is pointed out that the recent progress in magnetospheric physics has made it possible to understand the solar wind-magnetosphere interaction in terms of a dynamo process. An insight has also been obtained regarding the mechanism by which solar activities cause the power of the solar wind-magnetosphere dynamo to vary. New information has also been attained on the processes related

  14. Solar-wind energy conversion system

    Microsoft Academic Search

    1984-01-01

    A combined solar-wind energy conversion system in which the combined effects of solar and wind energy are utilized in raising water from a lower to an upper water storage tank to increase its potential energy for generation of electricity. Incoming solar energy heats water to form steam which is temporarily stored. The stored steam is vented to one of first

  15. 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.

  16. Solar Wind's Effect on Earth

    NSDL National Science Digital Library

    The Sun produces 'solar wind', a continuous flow of charged particles that can affect us on Earth. It may also release huge storms of charged particles, called coronal mass ejections, that can disrupt communications, navigation systems, and satellites; and cause power outages, such as the extensive Canadian blackout in 1989. This video segment introduces viewers to coronal mass ejections, their effects on Earth's magnetosphere and atmosphere, and their potentially damaging effects on satellites, power grids, and other human infrastructure. The segment is four minutes forty-four seconds in length.

  17. The global nature of solar cycle variations of the solar wind dynamic pressure

    E-print Network

    Richardson, John

    1 The global nature of solar cycle variations of the solar wind dynamic pressure John Richardson: SOLAR WIND DYNAMIC PRESSURE #12;2 Abstract. The solar wind dynamic pressure measured near the ecliptic-scale variation of the solar wind dynamic pressure is the same at all latitudes. Thus the solar wind source varies

  18. 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

  19. 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's surface composition is an important factor in how red its surface can become. After the first million years, the surface "tans" much more slowly. At that stage, the colour depends more on composition than on age. Moreover, the observations reveal that collisions cannot be the main mechanism behind the high proportion of "fresh" surfaces seen among near-Earth asteroids. Instead, these "fresh-looking" surfaces may be the results of planetary encounters, where the tug of a planet has "shaken" the asteroid, exposing unaltered material. Thanks to these results, astronomers will now be able to understand better how the surface of an asteroid -- which often is the only thing we can observe -- reflects its history. More information This result was presented in a paper published this week in the journal Nature, "Solar wind as the origin of rapid reddening of asteroid surfaces", by P. Vernazza et al. The team is composed of Pierre Vernazza (ESA), Richard Binzel (MIT, Cambridge, USA), Alessandro Rossi (ISTI-CNR, Pisa, Italy), Marcello Fulchignoni (Paris Observatory, France), and Mirel Birlan (IMCCE, CNRS-8028, Paris Observatory, France). A PDF file can be downloaded here. Notes [1] Meteorites are small fragments of asteroids that fall on Earth. While a meteorite enters the Earth's atmosphere its surface can melt and be partially charred by the intense heat. Nevertheless, the meteorite interior remains unaffected, and can be studied in a laboratory, providing a wealth of information on the nature and composition of asteroids. [2] An asteroid family is a group of asteroids that are on similar orbits around the Sun. The members of a given family are believed to be the fragments of a larger asteroid that was destroyed during a collision. [3] The surface of an asteroid is affected by the highly energetic particles forming the solar wind. These particles partially destroy the molecules and crystals on the surface, re-arranging them in other combinations. Over time, these changes

  20. Neutral interstellar gas atoms reducing the solar wind Mach number and fractionally neutralizing the solar wind

    Microsoft Academic Search

    Hans J. Fahr; Daniel Rucinski

    1999-01-01

    Many stars are known to drive stellar winds of the solar wind type. Thus when moving through the ambient interstellar medium these stars not simply ionize this medium but also interact as moving stellar wind systems. Only neutral interstellar gas components can directly enter the inner stellar wind region and there undergo charge exchange reactions with the supersonic stellar wind

  1. Ulysses' return to the slow solar wind

    Microsoft Academic Search

    D. J. McComas; S. J. Bame; B. L. Barraclough; W. C. Feldman; H. O. Funsten; J. T. Gosling; P. Riley; R. Skoug; A. Balogh; R. Forsyth; B. E. Goldstein; M. Neugebauer

    1998-01-01

    After ten long years of wandering the uncharted seas, Ulysses returned to his home port of Ithaca. Similarly, after its unprecedented five year odyssey through the previously uncharted regions over the poles of the Sun, the Ulysses spacecraft has returned to the slow, variable solar wind which dominates observations near the ecliptic plane. Solar wind plasma and magnetic field observations

  2. Direct observations of solar-wind particles

    Microsoft Academic Search

    A. J. Hundhausen

    1968-01-01

    Direct observations of solar-wind particles are discussed in detail. A well-defined ‘quiet state’ of the solar wind is indicated by observations made from 1962 to 1967. The plasma properties in this quiet state are compared with those predicted by hydrodynamic models of the coronal expansion. While the basic flow parameters are predicted with reasonable accuracy by these models, the thermal

  3. Solar wind interaction with Jupiter's magnetosphere

    Microsoft Academic Search

    P. A. Delamere; F. Bagenal

    2010-01-01

    We present a review of observations and theories of the dynamics of Jupiter's magnetosphere from Pioneer to New Horizons. We suggest that Jupiter's solar wind–driven magnetospheric flows are due primarily to viscous processes at the magnetopause boundary. Jupiter's magnetopause boundary is determined by a pressure balance between the solar wind dynamic pressure and the magnetospheric high-? plasma. We discuss how

  4. Expansion effects on solar wind hybrid simulations

    SciTech Connect

    Parashar, Tulasi N.; Velli, Marco; Goldstein, Bruce E. [NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2013-06-13

    Ion kinetic simulations of the solar wind using hybrid codes can model local wave input, heating and instabilities, but generally do not include long term evolution effects in the expanding solar wind. We further develop the expanding box model used in earlier studies to include the mirror force effects and study their role in the evolution of the proton distribution functions in the outer corona and inner heliosphere. The mirror force, significant in the acceleration region of the solar wind, is required for consistency with the conservation of magnetic moment of particles in the expanding wind. We present preliminary results from the modified 1D expanding box hybrid (EBHM) simulations.

  5. Alfvénic fluctuations in ``newborn'' polar solar wind

    NASA Astrophysics Data System (ADS)

    Bavassano, B.; Pietropaolo, E.; Bruno, R.

    2005-06-01

    The 3-D structure of the solar wind is strongly dependent upon the Sun's activity cycle. At low solar activity a bimodal structure is dominant, with a fast and uniform flow at the high latitudes, and slow and variable flows at low latitudes. Around solar maximum, in sharp contrast, variable flows are observed at all latitudes. This last kind of pattern, however, is a relatively short-lived feature, and quite soon after solar maximum the polar wind tends to regain its role. The plasma parameter distributions for these newborn polar flows appear very similar to those typically observed in polar wind at low solar activity. The point addressed here is about polar wind fluctuations. As is well known, the low-solar-activity polar wind is characterized by a strong flow of Alfvénic fluctuations. Does this hold for the new polar flows too? An answer to this question is given here through a comparative statistical analysis on parameters such as total energy, cross helicity, and residual energy, that are of general use to describe the Alfvénic character of fluctuations. Our results indicate that the main features of the Alfvénic fluctuations observed in low-solar-activity polar wind have been quickly recovered in the new polar flows developed shortly after solar maximum. Keywords. Interplanetary physics (MHD waves and turbulence; Sources of the solar wind) Space plasma physics (Turbulence)

  6. The abundances of elements and isotopes in the solar wind

    NASA Technical Reports Server (NTRS)

    Gloeckler, George; Geiss, Johannes

    1988-01-01

    Studies of the chemical and isotopic composition of the solar wind are reviewed. Solar wind abundance measurements are discussed and solar wind, coronal, and photospheric abundances for elements between H and Fe are presented. Also, consideration is given to the determination of the solar wind isotopic composition of the noble gases using foil collection techniques and the observation of solar wind heavy ions with the mass per charge spectrometer on ISEE-3. Other topics include solar wind observations with solid state detectors, solar wind abundances in the magnetosheath and the plasma sheet, and high-mass resolution measurements of chemical elements and isotopes in the solar wind.

  7. SOLAR AND WIND ELECTRICITY IN AUSTRALIA

    Microsoft Academic Search

    Andrew Blakers

    This paper examines the renewable generation of electricity in Australia from photovoltaics (PV), solar thermal electricity (STE) and wind. PV, STE and wind have immense resources and small environmental impacts even when deployed on very large scales. They are the only fully sustainable technologies able to completely replace fossil and nuclear electricity generation during this century. Wind energy is now

  8. Theoretical studies of the solar wind phenomenon

    Microsoft Academic Search

    E. N. Parker

    1969-01-01

    This paper is a review of current theoretical topics concerning the solar wind. Broadly speaking the questions outstanding at the present time concern the loss of angular momentum to the sun, the origin of the fluctuations observed in the wind at the orbit of earth, conditions in the wind in regions yet unvisited by spacecraft (inside the orbit of Venus,

  9. Solar wind parameters and magnetospheric coupling studies

    NASA Technical Reports Server (NTRS)

    King, Joseph H.

    1986-01-01

    This paper presents distributions, means, and standard deviations of the fluxes of solar wind protons, momentum, and energy as observed near earth during the solar quiet and active years 1976 and 1979. Distributions of ratios of energies (Alfven Mach number, plasma beta) and distributions of interplanetary magnetic field orientations are also given. Finally, the uncertainties associated with the use of the libration point orbiting ISEE-3 spacecraft as a solar wind monitor are discussed.

  10. Coronal Heating versus Solar Wind Acceleration

    E-print Network

    Steven R. Cranmer

    2004-09-29

    Parker's initial insights from 1958 provided a key causal link between the heating of the solar corona and the acceleration of the solar wind. However, we still do not know what fraction of the solar wind's mass, momentum, and energy flux is driven by Parker-type gas pressure gradients, and what fraction is driven by, e.g., wave-particle interactions or turbulence. SOHO has been pivotal in bringing these ideas back to the forefront of coronal and solar wind research. This paper reviews our current understanding of coronal heating in the context of the acceleration of the fast and slow solar wind. For the fast solar wind, a recent model of Alfven wave generation, propagation, and non-WKB reflection is presented and compared with UVCS, SUMER, radio, and in-situ observations at the last solar minimum. The derived fractions of energy and momentum addition from thermal and nonthermal processes are found to be consistent with various sets of observational data. For the more chaotic slow solar wind, the relative roles of steady streamer-edge flows (as emphasized by UVCS abundance analysis) versus bright blob structures (seen by LASCO) need to be understood before the relation between streamer heating and and slow-wind acceleration can be known with certainty. Finally, this presentation summarizes the need for next-generation remote-sensing observations that can supply the tight constraints needed to unambiguously characterize the dominant physics.

  11. Solar Wind Acceleration Models in SWMF

    Microsoft Academic Search

    O. Cohen; I. V. Sokolov; M. Velli; T. I. Gombosi

    2006-01-01

    The choice of the solar wind model in numerical simulations of the processes in the Solar Corona (SC), Inner Heliosphere (IH) and Outer Heliosphere (OH) is a matter of a crucial importance. Since the available theoretical models for the turbulent processes and turbulent heating in the solar corona do not provide a reliable and quantitatively accurate agreement with the observed

  12. Lognormal distributions and spectra of solar wind plasma fluctuations: Wind 19951998

    E-print Network

    Richardson, John

    Lognormal distributions and spectra of solar wind plasma fluctuations: Wind 1995­1998 L. F. Burlaga with large tails. There remains a need for dynamical models of the solar wind that incorporate and describe both deterministic and statistical properties of the solar wind. 1. Introduction The solar wind

  13. Electric Solar Wind Sail in tailwind

    NASA Astrophysics Data System (ADS)

    Janhunen, P.; Merikallio, S.; Toivanen, P.; Polkko, J.; Haeggström, E.; Seppänen, H.; Kurppa, R.; Ukkonen, J.; Ylitalo, T.; Kiprich, S.; Koivisto, H.; Kalvas, T.; Tarvainen, O.; Kauppinen, J.; Thornell, G.; Kratz, H.; Sundqvist, J.; Grönland, T.-A.; Johansson, H.; Rangsten, P.; Vinterhav, E.; Noorma, M.; Envall, J.; Lätt, S.; Allik, V.; Voormansik, K.; Kvell, U.; Lebreton, J.-P.; Hallikainen, M.; Praks, J.; Krömer, O.; Rosta, R.; Salminen, P.; Mengali, G.; Quarta, A.; Aliasi, G.; Marcuccio, S.; Pergola, P.; Giusti, N.

    2011-10-01

    The Electric Solar Wind Sail (E-sail) is a novel propulsion concept that enables faster space travel to many solar system targets. E-sail uses charged solar wind particles as the source of its propulsion. This is achieved by deploying long, conducting and charged tethers, which get pushed by the solar wind by Coulomb drag [1]. E-sail technology is being developed to technical readiness level (TRL) 4-5 by the European Union's Seventh Framework Programme for Research and Technological Development, EU FP7, in a project named ESAIL (http://www.electric-sailing.fi/fp7). Prototypes of the key parts are to be produced. The design will be scalable so that a real solar wind demonstration mission could be scaled up from them. We review here the latest results of the constantly evolving E-sail project.

  14. 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.

  15. Global Network of Slow Solar Wind N. U. Crooker1

    E-print Network

    Zhao, Xuepu

    Global Network of Slow Solar Wind N. U. Crooker1 Center for Space Physics, Boston University 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

  16. The Solar Wind and Its Interaction with the Interstellar Medium

    E-print Network

    Richardson, John

    The Solar Wind and Its Interaction with the Interstellar Medium John D. Richardson Abstract The solar wind is a magnetized plasma of ions and electrons which flows outward from the Sun. This chapter begins with a brief history of the discovery of the solar wind. Solar wind properties at 1 AU

  17. 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.

  18. Turbulence in the Solar Atmosphere and Solar Wind

    NASA Astrophysics Data System (ADS)

    Petrosyan, A.; Balogh, A.; Goldstein, M. L.; Léorat, J.; Marsch, E.; Petrovay, K.; Roberts, B.; von Steiger, R.; Vial, J. C.

    2010-10-01

    The objective of this review article is to critically analyze turbulence and its role in the solar atmosphere and solar wind, as well as to provide a tutorial overview of topics worth clarification. Although turbulence is a ubiquitous phenomenon in the sun and its heliosphere, many open questions exist concerning the physical mechanisms of turbulence generation in solar environment. Also, the spatial and temporal evolution of the turbulence in the solar atmosphere and solar wind are still poorly understood. We limit the scope of this paper (leaving out the solar interior and convection zone) to the magnetized plasma that reaches from the photosphere and chromosphere upwards to the corona and inner heliosphere, and place particular emphasis on the magnetic field structures and fluctuations and their role in the dynamics and radiation of the coronal plasma. To attract the attention of scientists from both the fluid-dynamics and space-science communities we give in the first two sections a phenomenological overview of turbulence-related processes, in the context of solar and heliospheric physics and with emphasis on the photosphere-corona connection and the coupling between the solar corona and solar wind. We also discuss the basic tools and standard concepts for the empirical analysis and theoretical description of turbulence. The last two sections of this paper give a concise review of selected aspects of oscillations and waves in the solar atmosphere and related fluctuations in the solar wind. We conclude with some recommendations and suggest topics for future research.

  19. 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.

  20. 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.

  1. Turbulence in solar wind and laboratory plasmas

    SciTech Connect

    Carbone, V. [Dipartimento di Fisica, Universita della Calabria, 87036 Rende (Italy) and Licryl Regional Laboratory/CNR, Ponte P. Bucci Cubo 33B, 87036 Rende (Italy)

    2010-06-16

    Recent studies of plasma turbulence based on measurements within solar wind and laboratory plasmas has been discussed. Evidences for the presence of a turbulent energy cascade, using the Yaglom's law for MHD turbulence, has been provided through data from the Ulysses spacecraft. This allows, for the first time, a direct estimate of the turbulent energy transfer rate, which can contribute to the in situ heating of the solar wind. The energy cascade has been evidenced also for ExB electrostatic turbulence in laboratory magnetized plasmas using measurements of intermittent transport (bursty turbulence) at the edge of the RFX-mod reversed field pinch plasma device. Finally the problem of the dispersive region of turbulence in solar wind above the ion-cyclotron frequency, where a spectral break is usually observed, and the problem of dissipation in a collisionless fluid as the solar wind, are briefly discussed.

  2. The solar wind in the outer heliosphere

    E-print Network

    Richardson, John D.

    The solar wind evolves as it moves outward due to interactions with both itself and with the circum-heliospheric interstellar medium. The speed is, on average, constant out to 30 AU, then starts a slow decrease due to the ...

  3. THREE-DIMENSIONAL NUMERICAL SIMULATIONS OF MAGNETIZED WINDS OF SOLAR-LIKE STARS

    SciTech Connect

    Vidotto, A. A.; Jatenco-Pereira, V. [University of Sao Paulo, Rua do Matao 1226, Sao Paulo, SP 05508-090 (Brazil); Opher, M. [George Mason University, 4400 University Drive, Fairfax, VA 22030-4444 (United States); Gombosi, T. I. [University of Michigan, 1517 Space Research Building, Ann Arbor, MI 48109-2143 (United States)], E-mail: aline@astro.iag.usp.br

    2009-07-01

    By means of self-consistent three-dimensional magnetohydrodynamics (MHD) numerical simulations, we analyze magnetized solar-like stellar winds and their dependence on the plasma-{beta} parameter (the ratio between thermal and magnetic energy densities). This is the first study to perform such analysis solving the fully ideal three-dimensional MHD equations. We adopt in our simulations a heating parameter described by {gamma}, which is responsible for the thermal acceleration of the wind. We analyze winds with polar magnetic field intensities ranging from 1 to 20 G. We show that the wind structure presents characteristics that are similar to the solar coronal wind. The steady-state magnetic field topology for all cases is similar, presenting a configuration of helmet streamer-type, with zones of closed field lines and open field lines coexisting. Higher magnetic field intensities lead to faster and hotter winds. For the maximum magnetic intensity simulated of 20 G and solar coronal base density, the wind velocity reaches values of {approx}1000 km s{sup -1} at r {approx} 20r {sub 0} and a maximum temperature of {approx}6 x 10{sup 6} K at r {approx} 6r {sub 0}. The increase of the field intensity generates a larger 'dead zone' in the wind, i.e., the closed loops that inhibit matter to escape from latitudes lower than {approx}45 deg. extend farther away from the star. The Lorentz force leads naturally to a latitude-dependent wind. We show that by increasing the density and maintaining B {sub 0} = 20 G the system recover back to slower and cooler winds. For a fixed {gamma}, we show that the key parameter in determining the wind velocity profile is the {beta}-parameter at the coronal base. Therefore, there is a group of magnetized flows that would present the same terminal velocity despite its thermal and magnetic energy densities, as long as the plasma-{beta} parameter is the same. This degeneracy, however, can be removed if we compare other physical parameters of the wind, such as the mass-loss rate. We analyze the influence of {gamma} in our results and we show that it is also important in determining the wind structure.

  4. The Effects of Solar Wind Dynamic Pressure on the Coupling of Energy between the Solar Wind and Magnetosphere

    Microsoft Academic Search

    Elizabeth Mitchell; Ramon Lopez

    2009-01-01

    Space physics seeks to understand the solar wind conditions which determine the interactions between the magnetosphere to the solar wind. In this pursuit, we are considering the effects of the changes in the solar wind dynamic pressure on the coupling between the solar wind electric field and the ring current injection rate (RCIR). The RCIR indicates the scale of the

  5. 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.

  6. Solar wind-magnetosphere energy input functions

    Microsoft Academic Search

    L. F. Bargatze; R. L. McPherron; D. N. Baker

    1985-01-01

    A new formula for the solar wind-magnetosphere energy input parameter, P\\/sub i\\/, is sought by applying the constraints imposed by dimensional analysis. Applying these constraints yields a general equation for P\\/sub i\\/ which is equal to rho V³l\\/sub CF\\/²F(M\\/sub A\\/,theta) where, rho V³ is the solar wind kinetic energy density and l\\/sub CF\\/² is the scale size of the magnetosphere's

  7. Pluto's Interaction with the Solar Wind

    Microsoft Academic Search

    Fran Bagenal; Ralph L. McNutt Jr.

    1989-01-01

    If Pluto's atmospheric escape rate is significantly greater than 1.5 x 10 to the 27th molecules\\/s then the interaction with the tenuous solar wind at 30 A.U. will be like that of a comet. There will be extensive ion pick-up upstream and the size of the interaction region will vary directly with variations in the solar wind flux. If the

  8. Empirical Solar Wind Forecasting from the Chromosphere

    E-print Network

    Robert J. Leamon; Scott W. McIntosh

    2007-01-12

    Recently, we correlated the inferred structure of the solar chromospheric plasma topography with solar wind velocity and composition data measured at 1AU. We now offer a physical justification of these relationships and present initial results of a empirical prediction model based on them. While still limited by the fundamentally complex physics behind the origins of the solar wind and how its structure develops in the magnetic photosphere and expands into the heliosphere, our model provides a near continuous range of solar wind speeds and composition quantities that are simply estimated from the inferred structure of the chromosphere. We suggest that the derived quantities may provide input to other, more sophisticated, prediction tools or models such as those to study Coronal Mass Ejections (CME) propagation and Solar Energetic Particle (SEP) generation.

  9. Combined Solar and Wind Energy Systems

    Microsoft Academic Search

    Y. Tripanagnostopoulos; M. Souliotis; Th. Makris

    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)

  10. Space Weathering Agent: Solar Wind

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2009-08-01

    In the vacuum of space, the interactions of energetic particles with the surfaces of airless planetary bodies cause radiation damage, chemical changes, optical changes, erosional sputtering, and heat. This is an essential part of the process called space weathering. A group at the Laboratory for Atomic and Surface Physics at the University of Virginia specialize in experiments, among other things, where they bombard surfaces with charged particles to see what happens. Recent work by Mark Loeffler, Cathy Dukes, and Raul Baragiola focused on what happens to olivine mineral grains when they are irradiated by helium ions to better understand the effects of solar wind on the surface composition and, therefore, appearance of asteroids. Their experiments were the first to measure chemical and reflectance changes in olivine before and after irradiation while still under vacuum conditions. The resulting changes in the reflectance spectra of olivine slabs and powders are directly correlated with the formation of metallic iron in the very outer surface of the mineral grains.

  11. About the correlation between solar micro bursts and the change of the solar wind parameters

    E-print Network

    Juan Carlos Martinez Oliveros; Daniel Ricardo Izquierdo P

    2005-08-02

    The Sun is the closest star to our planet and it is the most studied, perhaps, there exist too much procesess not-understood. One of the solar processes that have a direct interaction with the earth is the solar wind. The solar wind is defined as the plasma expulsed from the solar atmosphere, this wind was cataloged and is considered that have three components: - Passive solar wind: Is the constant component of the solar wind. - Supersonic and quasistady flux. - Sporadic supersonic flux. We present and brief explanation of the Parker's model of the solar wind and a correlation analysis between solar micro radio bursts and the change of the solar wind parameters.

  12. Western Wind and Solar Integration Study

    SciTech Connect

    Lew, D.; Piwko, R.; Jordan, G.; Miller, N.; Clark, K.; Freeman, L.; Milligan, M.

    2011-01-01

    The Western Wind and Solar Integration Study (WWSIS) is one of the largest regional wind and solar integration studies to date. It was initiated in 2007 to examine the operational impact of up to 35% energy penetration of wind, photovoltaics (PV), and concentrating solar power (CSP) on the power system operated by the WestConnect group of utilities in Arizona, Colorado, Nevada, New Mexico, and Wyoming (see study area map). WestConnect also includes utilities in California, but these were not included because California had already completed a renewable energy integration study for the state. This study was set up to answer questions that utilities, public utilities commissions, developers, and regional planning organizations had about renewable energy use in the west: (1) Does geographic diversity of renewable energy resource help mitigate variability; (2) How do local resources compare to out-of-state resources; (3) Can balancing area cooperation help mitigate variability; (4) What is the role and value of energy storage; (5) Should reserve requirements be modified; (6) What is the benefit of forecasting; and (7) How can hydropower help with integration of renewables? The Western Wind and Solar Integration Study is sponsored by the U.S. Department of Energy (DOE) and run by NREL with WestConnect as a partner organization. The study follows DOE's 20% Wind Energy by 2030 report, which did not find any technical barriers to reaching 20% wind energy in the continental United States by 2030. This study and its partner study, the Eastern Wind Integration and Transmission Study, performed a more in-depth operating impact analysis to see if 20% wind energy was feasible from an operational level. In DOE/NREL's analysis, the 20% wind energy target required 25% wind energy in the western interconnection; therefore, this study considered 20% and 30% wind energy to bracket the DOE analysis. Additionally, since solar is rapidly growing in the west, 5% solar was also considered in this study. The goal of the Western Wind and Solar Integration Study is to understand the costs and operating impacts due to the variability and uncertainty of wind, PV, and CSP on the grid. This is mainly an operations study, (rather than a transmission study), although different scenarios model different transmission build-outs to deliver power. Using a detailed power system production simulation model, the study identifies operational impacts and challenges of wind energy penetration up to 30% of annual electricity consumption.

  13. 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.

  14. 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.

  15. Comparison of VLF Wave Activity in the Solar Wind During Solar Maximum and Minimum

    E-print Network

    California at Berkeley, University of

    Comparison of VLF Wave Activity in the Solar Wind During Solar Maximum and Minimum: Ulysses and intermediate speed solar wind. The maximum intensity of the electromagnetic waves for the two solar cycle are similar for the slow and intermediate solar wind in both solar maximum and minimum phases. It is also

  16. 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.

  17. Simulating Upstream Solar Wind Conditions at Mercury: Results From two Independent Solar Wind Models

    Microsoft Academic Search

    B. Zieger; K. C. Hansen; O. Cohen; T. I. Gombosi; T. H. Zurbuchen; B. J. Anderson; H. Korth

    2009-01-01

    The knowledge of upstream solar wind conditions at Mercury is essential not only for modeling the Hermian magnetosphere-exosphere-surface system but also for interpreting the pioneering in situ observations made by MESSENGER during the January and October 2008 flybys. For this reason, and due to the fact that the MESSENGER plasma instruments cannot see the solar wind, we intend to provide

  18. Solar Wind Forecasting with Coronal Holes

    E-print Network

    S. Robbins; C. J. Henney; J. W. Harvey

    2007-01-09

    An empirical model for forecasting solar wind speed related geomagnetic events is presented here. The model is based on the estimated location and size of solar coronal holes. This method differs from models that are based on photospheric magnetograms (e.g., Wang-Sheeley model) to estimate the open field line configuration. Rather than requiring the use of a full magnetic synoptic map, the method presented here can be used to forecast solar wind velocities and magnetic polarity from a single coronal hole image, along with a single magnetic full-disk image. The coronal hole parameters used in this study are estimated with Kitt Peak Vacuum Telescope He I 1083 nm spectrograms and photospheric magnetograms. Solar wind and coronal hole data for the period between May 1992 and September 2003 are investigated. The new model is found to be accurate to within 10% of observed solar wind measurements for its best one-month periods, and it has a linear correlation coefficient of ~0.38 for the full 11 years studied. Using a single estimated coronal hole map, the model can forecast the Earth directed solar wind velocity up to 8.5 days in advance. In addition, this method can be used with any source of coronal hole area and location data.

  19. Global MHD Modeling of the Solar Corona and Solar Wind

    Microsoft Academic Search

    A. Usmanov; M. Goldstein

    2004-01-01

    We present a global three-dimensional steady-state MHD model of the solar corona and solar wind that uses observations of the photospheric magnetic field in the prescription of boundary condition. As part of the boundary conditions, we also specify a flux of Alfvén waves that emanates from the Sun. The Alfvén waves provide additional acceleration for the coronal outflow in the

  20. Ion Heating in the Solar Corona and Solar Wind

    Microsoft Academic Search

    Steven Cranmer

    2009-01-01

    The solar corona is the hot, ionized outer atmosphere of the Sun that expands into interplanetary space as a supersonic solar wind. This tenuous medium is a unique laboratory for the study of magnetohydrodynamics (MHD) and plasma physics with ranges of parameters that are inaccessible on Earth. The last decade has seen significant progress toward identifying and characterizing the processes

  1. Quiet-time solar wind superhalo electrons at solar minimum

    NASA Astrophysics Data System (ADS)

    Wang, Linghua; Lin, Robert P.; Salem, Chadi; Pulupa, Marc; Larson, Davin E.; Yoon, Peter H.; Luhmann, Janet G.

    2013-06-01

    We survey the statistical properties of ~2-20 keV superhalo electrons in the solar wind measured by the STEREO/STE instrument during quiet-time periods from 2007 March through 2009 March at solar minimum. The observed quiet-time superhalo electrons have a nearly isotropic angular distribution and a power-law spectrum, f ?v-?, with ? ranging from 5 to 8.7, with nearly half between 6.5 and 7.5, and an average index of 6.69+/-0.90. The integrated density of quiet-time superhalo electrons at 2-20 keV ranges from 10-8 cm-3 to 10-6 cm-3, about 10-9-10-6 of the solar wind density, and it, as well as the power-law spectrum, shows no correlation with solar wind protons. The density of superhalo electrons decreases by approximately one order of magnitude between early 2007 and early 2009, probably reflecting the decay of solar cycle 23 and the approach to its unusually deep activity minimum, while the power-law spectral index ? has no solar-cycle variation. These quiet-time superhalo electrons are present even in the absence of any solar activity, e.g., active regions, flares or microflares, type III radio bursts, etc., suggesting that they may be accelerated by resonant wave-particle interactions in the interplanetary medium, or by nonthermal processes related to the acceleration of the solar wind such as nanoflares.

  2. Solar and solar-wind isotopic compositions

    Microsoft Academic Search

    Roger C. Wiens; Peter Bochsler; Donald S. Burnett; Robert F. Wimmer-Schweingruber

    2004-01-01

    With only a few exceptions, the solar photosphere is thought to have retained the mean isotopic composition of the original solar nebula, so that, with some corrections, the photosphere provides a baseline for comparison of all other planetary materials. There are two sources of information on the photospheric isotopic composition: optical observations, which have succeeded in determining a few isotopic

  3. Solar wind proton deposition into the Martian atmosphere

    Microsoft Academic Search

    Stephen H. Brecht

    1997-01-01

    The direct impact of solar wind H + with the planet Mars is calculated using a three- dimensional hybrid particle code. The simulation results show a strong dependence on solar wind velocity and interplanetary magnetic field angle with the solar wind velocity vector. The energy fluxes calculated approach the solar EUV heating rates fxom photoelectrons and are found to be

  4. Titan interaction with the supersonic solar wind

    E-print Network

    Bertucci, C; Kurth, W S; Hospodarsky, G; Mitchell, D; Sergis, N; Edberg, N J T; Dougherty, M K

    2014-01-01

    After 9 years in the Saturn system, the Cassini spacecraft finally observed Titan in the supersonic solar wind. These unique observations reveal that Titan interaction with the solar wind is in many ways similar to un-magnetized planets Mars and Venus in spite of the differences in the properties of the solar plasma in the outer solar system. In particular, Cassini detected a collisionless, supercritical bow shock and a well-defined induced magnetosphere filled with mass-loaded interplanetary magnetic field lines, which drape around Titan ionosphere. Although the flyby altitude may not allow the detection of an ionopause, Cassini reports enhancements of plasma density compatible with plasma clouds or streamers in the flanks of its induced magnetosphere or due to an expansion of the induced magnetosphere. Because of the upstream conditions, these observations are also relevant for unmagnetized bodies in the outer solar system such as Pluto, where kinetic processes are expected to dominate.

  5. Titan's interaction with the supersonic solar wind

    NASA Astrophysics Data System (ADS)

    Bertucci, C.; Hamilton, D. C.; Kurth, W. S.; Hospodarsky, G.; Mitchell, D.; Sergis, N.; Edberg, N. J. T.; Dougherty, M. K.

    2015-01-01

    9 years in the Saturn system, the Cassini spacecraft finally observed Titan in the supersonic and super-Alfvénic solar wind. These unique observations reveal that Titan's interaction with the solar wind is in many ways similar to unmagnetized planets Mars and Venus and active comets in spite of the differences in the properties of the solar plasma in the outer solar system. In particular, Cassini detected a collisionless, supercritical bow shock and a well-defined induced magnetosphere filled with mass-loaded interplanetary magnetic field lines, which drape around Titan's ionosphere. Although the flyby altitude may not allow the detection of an ionopause, Cassini reports enhancements of plasma density compatible with plasma clouds or streamers in the flanks of its induced magnetosphere or due to an expansion of the induced magnetosphere. Because of the upstream conditions, these observations may be also relevant to other bodies in the outer solar system such as Pluto, where kinetic processes are expected to dominate.

  6. Solar winds along curved magnetic field lines

    E-print Network

    Li, Bo; Chen, Yao

    2011-01-01

    Both remote-sensing measurements using the interplanetary scintillation (IPS) technique and in situ measurements by the Ulysses spacecraft show a bimodal structure for the solar wind at solar minimum conditions. At present what makes the fast wind fast and the slow wind slow still remains to be answered. While a robust empirical correlation exists between the coronal expansion rate $f_c$ of the flow tubes and the speeds $v$ measured in situ, further data analysis suggests that $v$ depends on more than just $f_c$. We examine whether the non-radial shape of field lines, which naturally accompanies any non-radial expansion, could be an additional geometrical factor. We solved the transport equations incorporating the heating due to turbulent Alfv\\'en waves for an electron-proton solar wind along curved field lines given by an analytical magnetic field model, representative of a solar minimum corona. The field line shape is found to influence substantially the solar wind parameters, reducing the asymptotic speed ...

  7. The Solar Wind Ion Analyzer for MAVEN

    NASA Astrophysics Data System (ADS)

    Halekas, J. S.; Taylor, E. R.; Dalton, G.; Johnson, G.; Curtis, D. W.; McFadden, J. P.; Mitchell, D. L.; Lin, R. P.; Jakosky, B. M.

    2013-11-01

    The Solar Wind Ion Analyzer (SWIA) on the MAVEN mission will measure the solar wind ion flows around Mars, both in the upstream solar wind and in the magneto-sheath and tail regions inside the bow shock. The solar wind flux provides one of the key energy inputs that can drive atmospheric escape from the Martian system, as well as in part controlling the structure of the magnetosphere through which non-thermal ion escape must take place. SWIA measurements contribute to the top level MAVEN goals of characterizing the upper atmosphere and the processes that operate there, and parameterizing the escape of atmospheric gases to extrapolate the total loss to space throughout Mars' history. To accomplish these goals, SWIA utilizes a toroidal energy analyzer with electrostatic deflectors to provide a broad 360?×90? field of view on a 3-axis spacecraft, with a mechanical attenuator to enable a very high dynamic range. SWIA provides high cadence measurements of ion velocity distributions with high energy resolution (14.5 %) and angular resolution (3.75?×4.5? in the sunward direction, 22.5?×22.5? elsewhere), and a broad energy range of 5 eV to 25 keV. Onboard computation of bulk moments and energy spectra enable measurements of the basic properties of the solar wind at 0.25 Hz.

  8. Asymptotic Theory of Solar Wind Electrons

    NASA Astrophysics Data System (ADS)

    Kim, Sunjung; Yoon, Peter H.; Choe, G. S.; Wang, Linghua

    2015-06-01

    This paper presents a theory for the asymptotically steady-state solar wind electron velocity distribution function (VDF) in a local equilibrium with plasma wave turbulence. By treating the local solar wind electron VDF as a superposition of three populations—the low-energy Maxwellian core electrons with an energy range of tens of eV, the intermediate ? {{10}2}–103 eV energy-range halo electrons, and the high ? {{10}3}–105 eV energy-range superhalo electrons—the present paper puts forth a model in which the halo electrons are in dynamical steady state with the pervasive whistler fluctuations, while the superhalo electrons maintain dynamical steady-state equilibrium with the Langmuir fluctuations, known as the quasi-thermal noise. Customary models of the solar wind electrons include only the Maxwellian core and the halo (plus highly field-aligned strahl). While the present paper does not consider the strahl population in the discussion, the highly energetic superhalo component, which is observed to be present in all solar conditions, is explicitly taken into account as part of the total solar wind electron model. Comparisons with STEREO and WIND spacecraft observations are also made.

  9. Laboratory Facility for Simulating Solar Wind Sails

    SciTech Connect

    Funaki, Ikkoh [Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, 229-8510 (Japan); JST/CREST, Kawaguchi, Saitama, 332-0012 (Japan); Ueno, Kazuma; Oshio, Yuya [Graduate University for Advanced Studies, Sagamihara, Kanagawa, 229-8510 (Japan); Ayabe, Tomohiro; Horisawa, Hideyuki [Tokai University, Hiratsuka, Kanagawa, 259-1292 (Japan); Yamakawa, Hiroshi [Kyoto University, Uji, Kyoto, 611-0011 (Japan); JST/CREST, Kawaguchi, Saitama, 332-0012 (Japan)

    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.

  10. THE SOLAR WIND AND SUPRATHERMAL ION COMPOSITION INVESTIGATION ON THE WIND SPACECRAFT

    E-print Network

    Christian, Eric

    composition of solar wind ions, and (2) the differential energy spectra, abundances and ionization or chargeTHE SOLAR WIND AND SUPRATHERMAL ION COMPOSITION INVESTIGATION ON THE WIND SPACECRAFT G. GLOECKLER in Belgium. #12;80 G. GLOECKLER ET AL. Abstract. The Solar Wind and Suprathermal Ion Composition Experiment

  11. Simulation of asymmetric solar wind electron distributions

    SciTech Connect

    Ryu, Chang-Mo; Ahn, Hee-Chul; Rhee, Tongnyeol [Department of Physics, POSTECH, Pohang (Korea, Republic of); Yoon, P. H. [Massachusetts Technological Laboratory, Inc., 330 Pleasant Street, Belmont, Massachusetts 02478 (United States); IPST, University of Maryland, College Park, Maryland 20742 (United States); Ziebell, L. F. [Instituto de Fisica, UFRGS, Porto Alegre, Rio Grande do Sul (Brazil); Gaelzer, R. [Instituto de Fisica e Matematica, UFPel, Pelotas, Rio Grande do Sul (Brazil); Vinas, A. F. [NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)

    2009-06-15

    The electron distributions detected in the solar wind feature varying degrees of anisotropic high-energy tail. In a recent work the present authors numerically solved the one-dimensional electrostatic weak turbulence equations by assuming that the solar wind electrons are initially composed of thermal core plus field-aligned counterstreaming beams, and demonstrated that a wide variety of asymmetric energetic tail distribution may result. In the present paper, the essential findings in this work are tested by means of full particle-in-cell simulation technique. It is found that the previous results are largely confirmed, thus providing evidence that the paradigm of local electron acceleration to high-energy tail by self-consistently excited Langmuir turbulence may be relevant to the solar wind environment under certain circumstances. However, some discrepancies are found such that the nearly one-sided energetic tail reported in the numerical solution of the weak turbulence kinetic equation is not shown.

  12. Magnetohydrodynamic Simulations of the Solar Corona and Solar Wind Using a Boundary Treatment to Limit Solar Wind Mass Flux

    Microsoft Academic Search

    Keiji Hayashi

    2005-01-01

    Magnetohydrodynamic simulations of the solar corona and solar wind are sensitive to conditions in the sub-Alfvénic plasma at the base of the solar corona because the structure of the simulated solar corona is determined by the pressure balance of the plasma and the magnetic field. Therefore, it is important to construct an adequate boundary treatment for the sub-Alfvénic surface, and

  13. Comparison of the Genesis solar wind regime algorithm results with solar wind composition observed by ACE

    SciTech Connect

    Reisenfeld, D. B. (Daniel B.); Steinberg, J. T (John T.); Barraclough, B. L. (Bruce L.); Dors, E. E. (Eric E.); Weins, R. C. (Roger C.); Neugebauer, Marcia; Reinard, A. (Alysha)

    2002-01-01

    Launched on 8 August 2001, the NASA Genesis mission is now collecting samples of the solar wind in various materials, and will return those samples to Earth in 2004 for analysis. A primary science goal of Genesis is the determination of the isotopic and elemental composition of the solar atmosphere from the solar wind material returned. In particular, Genesis will provide measurements of those species that are not provided by solar and in situ observations. We know from in situ measurements that the solar wind exhibits compositional variations across different types of solar wind flows. Therefore, Genesis exposes different collectors to solar wind originating from three flow types: coronal hole, coronal mass ejection (CME), and interstream flows. Flow types are identified using in situ measurements of solar wind protons, alphas, and electrons from electrostatic analyzers carried by Genesis. The flow regime selection algorithm and subsequent collector deployment on Genesis act autonomously. We present an assessment of composition variations of O, He, and Mg ions observed by ACE/SWICS concurrent with Genesis observations, and compare these to the Genesis algorithm decisions. Not only does this serve as a test of the algorithm, the compilation of composition vs. regime will be important for comparison to the abundances determined from sample analysis at the end of the mission.

  14. 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.

  15. 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.

  16. Magnetohydrodynamic turbulence in the solar wind

    NASA Technical Reports Server (NTRS)

    Goldstein, Melvyn L.

    1995-01-01

    The fluctuations in magnetic field and plasma velocity in solar wind, which possess many features of fully developed magnetohydrodynamic (MHD) turbulence, are discussed. Direct spacecraft observations from 0.3 to over 20 AU, remote sensing radio scintillation observations, numerical simulations, and various models provide complementary methods that show that the fluctuations in the wind parameters undergo significant dynamical evolution independent of whatever turbulence might exist in the solar photosphere and corona. The Cluster mission, with high time resolution particle and field measurements and its variable separation strategies, should be able to provide data for answering many questions on MHD turbulence.

  17. 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.

  18. Measuring the Isotopic Composition of Solar Wind Noble Gases

    E-print Network

    5 Measuring the Isotopic Composition of Solar Wind Noble Gases Alex Meshik, Charles Hohenberg, Olga and processes leading to the variations observed and how the present solar wind noble gases may differ from and breccias, implanted with solar wind noble gases, did provide a needed ground truth, neither by themselves

  19. Anisotropic MHD Turbulence in the Interstellar Medium and Solar Wind

    E-print Network

    Ng, Chung-Sang

    Anisotropic MHD Turbulence in the Interstellar Medium and Solar Wind C. S. Ng Center for Magnetic (MHD) turbulence Observations in ISM and solar wind · Anisotropy due to magnetic field · Electron MHD density spectrum and spatial scales wave number density Kolmogorov law #12;Solar wind turbulence From

  20. The driving of the plasma sheet by the solar wind

    Microsoft Academic Search

    Joseph E. Borovsky; Michelle F. Thomsen; Richard C. Elphic

    1998-01-01

    The coupling of the plasma sheet to the solar wind is studied statistically using measurements from various satellite pairs: one satellite in the solar wind and one in either the magnetotail central plasma sheet or the near-Earth plasma sheet. It is found that the properties of the plasma sheet are highly correlated with the properties of the solar wind: specifically

  1. The Solar Wind, CMEs and the Origins of Heliospheric Activity

    E-print Network

    The Solar Wind, CMEs and the Origins of Heliospheric Activity Peter T. Gallagher School of Physics release o Coronal holes o Source of high-speed solar wind #12;peter.gallagher@tcd.ie #12;#12;peter.gallagher@tcd.ie #12;#12;The solar wind o Biermann (1951): comets showed excess ionization and abrupt changes

  2. Apollo 11 Solar Wind Composition Experiment: First Results

    Microsoft Academic Search

    F. Buehler; P. Eberhardt; J. Geiss; J. Meister; P. Signer

    1969-01-01

    The helium-4 solar wind flux during the Apollo 11 lunar surface excursion was (6.3 ± 1.2) × 106 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.

  3. The Solar Wind Around Pluto (SWAP) Instrument Aboard New Horizons

    E-print Network

    Stern, S. Alan

    1 The Solar Wind Around Pluto (SWAP) Instrument Aboard New Horizons D. McComas1,* , F. Allegrini1Comas@swri.edu) Abstract. The Solar Wind Around Pluto (SWAP) instrument on New Horizons will measure the interaction between the solar wind and ions created by atmospheric loss from Pluto. These measurements provide

  4. Evidence for Langmuir wave tunneling in the inhomogeneous solar wind

    E-print Network

    California at Berkeley, University of

    Evidence for Langmuir wave tunneling in the inhomogeneous solar wind A. J. Willes School of Physics tunneling in evanescent regions in the inhomogeneous solar wind. Incident Langmuir waves which are nearly for Langmuir wave tunneling in the inhomogeneous solar wind, J. Geophys. Res., 107(A10), 1320, doi:10

  5. Solar wind vs magnetosheath turbulence and Alfven vortices Olga Alexandrova

    E-print Network

    Demoulin, Pascal

    Solar wind vs magnetosheath turbulence and Alfv´en vortices Olga Alexandrova LESIA, Observatoire de-ID: 1607-7946/npg/2007-0000-0001 LOGO Solar wind vs magnetosheath turbulence and Alfv´en vortices Olga universal, but with an ex- ponential shape and not a power law (Frisch, 1995). The solar wind and the Earth

  6. Implications of the Deep Minimum for Slow Solar Wind Origin

    Microsoft Academic Search

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

    2009-01-01

    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,

  7. The Solar Wind Helium Abundance: Variation with Wind Speed and the Solar Cycle

    E-print Network

    Richardson, John

    in this paper is shown in Figure 1. DATA For this study we used data from the Faraday Cup portion of the SWE instrumenton the Wind spacecraft, Ogilvieet al [5]. The Faraday Cup data allow the determination of the solar

  8. The relative abundance of 3He(++) in the solar wind

    NASA Technical Reports Server (NTRS)

    Coplan, M. A.; Ogilvie, K. W.; Bochsler, P.; Geiss, J.

    1983-01-01

    Continuous measurements of solar wind 3He(++) and 4He(++) were made covering a full range of solar wind conditions. The average flux ratio derived from these data is 2310 + or - 50, in excellent agreement with the Apollo foil measurements. A probable correlation between average flux ratio and solar activity was found; however, an examination of the data during periods of 3He(++)-rich solar flares shows no detectable increase in 3He(++) in the solar wind.

  9. Relative abundance of 3He(++) in the solar wind

    SciTech Connect

    Coplan, M.A.; Ogilvie, K.W.; Bochsler, P.

    1983-11-01

    Continuous measurements of solar wind 3He(++) and 4He(++) were made covering a full range of solar wind conditions. The average flux ratio derived from these data is 2310 + or - 50, in excellent agreement with the Apollo foil measurements. A probable correlation between average flux ratio and solar activity was found however, an examination of the data during periods of 3He(++)-rich solar flares shows no detectable increase in 3He(++) in the solar wind.

  10. 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.

  11. Triggering of substorms by solar wind discontinuities

    Microsoft Academic Search

    S. Kokubun; R. L. McPherron; C.T. Russell

    1977-01-01

    In order to study the relationship between substorm occurrence and magnetospheric compression caused by solar wind discontinuities, 125 storm sudden commencements (ssc's) observed during the 4 years 1967-1970 were examined by using ground magnetograms, AE indices, and magnetic field data obtained by Explorer 33, 34, and 35 and OGO 5. Statistical and case studies confirm that geogmagnetic activity and interplanetary

  12. Magnetopause location under extreme solar wind conditions

    Microsoft Academic Search

    J.-H. Shue; P. Song; J. T. Steinberg; J. K. Chao; G. Zastenker; O. L. Vaisberg; S. Kokubun; H. J. Singer; T. R. Detman; H. Kawano

    1998-01-01

    During the solar wind dynamic pressure enhancement, around 0200 UT on January 11, 1997, at the end of the January 6-11 magnetic cloud event, the magnetopause was pushed inside geosynchronous orbit. The LANL 1994-084 and GMS 4 geosynchronous satellites crossed the magnetopause and moved into the magnetosheath. Also, the Geotail satellite was in the magnetosheath while the Interball 1 satellite

  13. Solar and wind energy resources and prediction

    Microsoft Academic Search

    Quanhua Liu; Qinxian Miao; Jue J. Liu; Wenli Yang

    2009-01-01

    Energy and environmental issues are among the most important problems of public concern. There are increasing debates about whether to resort to drilling more oil and mining more coal or to using renewable, sustainable, and clean resources such as solar and wind energies. Through our analyses and modeling on the basis of the National Center for Environment Prediction data, we

  14. Double ion streams in the solar wind

    Microsoft Academic Search

    W. C. Feldman; J. R. Asbridge; S. J. Bame; M. D. Montgomery

    1973-01-01

    Distinct interpenetrating ion streams have been identified in the solar wind for the first time. They are shown to be interplanetary in origin and to be associated with the filling in of regions of density rarefactions accompanying high-velocity streams. With few excep- tions, the ion stream with the lower-energy density flux has higher energy. Furthermore, nonradial magnetic field directions seem

  15. The energy balance of the solar wind

    NASA Technical Reports Server (NTRS)

    Hollweg, J. V.

    1981-01-01

    The effects of modifying some of the 'classical' assumptions underlying many of the solar wind models constructed over the past 20 years are examined in an effort to obtain both a better fit with the observations and a deeper understanding of the relevant physical processes.

  16. Solar Wind and Motion of Meteoroids

    E-print Network

    Jozef Klacka

    1999-10-04

    The effect of nonradial component of solar wind is discussed from the qualitative point of view. It is shown that the direction of nonradial component is opposite in comparison with the direction used in papers dealing with orbital evolution of meteoroids.

  17. Helium abundance in the solar wind

    Microsoft Academic Search

    K. W. Ogilvie; T. D. Wilkerson

    1969-01-01

    Observations of hydrogen and helium ions in the solar wind have been carried out by the Goddard Space Flight Center - University of Maryland plasma instrument on Explorer 34. These ions are completely separated by means of electrostatic and magnetic fields. The average value of the ratio of number densities is 0.051 ± .02, derived from over 3000 h of

  18. 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…

  19. Dispersive shock waves in the solar wind

    Microsoft Academic Search

    I. Ballai; E. Forgács-Dajka; A. Marcu

    2007-01-01

    Compressional waves in the solar wind propagating over large distances are likely to steepen into shock waves where the increase in the amplitude is balanced by dissipation. Dispersive effects caused by, e.g. Hall currents perpendicular to the ambient magnetic field can influence the generation and propagation of shock waves. In the present study the dispersion is considered weak but in

  20. Theoretical models for the solar wind

    Microsoft Academic Search

    E. Marsch

    1994-01-01

    Theoretical models for the solar wind are reviewed from the point of view that a hot corona cannot be simply assumed as a given inner boundary but rather as part of the overall problem and needs to be explained in the first place. Models including the transition region and the heating of the corona and the coronal radiative and conductive

  1. 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, blistering, and exfoliation of metallic surfaces to establish the order of magnitude ion fluence required for significant surface damage. Solar wind ion fluence environments will then be evaluated due to variations in solar wind conditions as a function of solar cycle for varying distances from the Sun using models for radial variations in solar wind ion number density, temperature, and velocity to determine where sputtering and blistering is most likely to be an issue. Finally, ion fluence statistics for varying radial distances from the Sun will be shown to establish the mission duration and radial distances from the Sun where missions will encounter sufficient ion fluence to exhibit damage to metallic surfaces.

  2. Electric solar wind sail mass budget model

    NASA Astrophysics Data System (ADS)

    Janhunen, P.; Quarta, A. A.; Mengali, G.

    2013-02-01

    The electric solar wind sail (E-sail) is a new type of propellantless propulsion system for Solar System transportation, which uses the natural solar wind to produce spacecraft propulsion. The E-sail consists of thin centrifugally stretched tethers that are kept charged by an onboard electron gun and, as such, experience Coulomb drag through the high-speed solar wind plasma stream. This paper discusses a mass breakdown and a performance model for an E-sail spacecraft that hosts a mission-specific payload of prescribed mass. In particular, the model is able to estimate the total spacecraft mass and its propulsive acceleration as a function of various design parameters such as the number of tethers and their length. A number of subsystem masses are calculated assuming existing or near-term E-sail technology. In light of the obtained performance estimates, an E-sail represents a promising propulsion system for a variety of transportation needs in the Solar System.

  3. Simulation study of solar wind push on a charged wire: basis of solar wind electric sail propulsion

    Microsoft Academic Search

    P. Janhunen; A. Sandroos

    2007-01-01

    One possibility for propellantless propulsion in space is to use the momentum flux of the solar wind. A way to set up a solar wind sail is to have a set of thin long wires which are kept at high positive potential by an onboard electron gun so that the wires repel and deflect incident solar wind protons. The efficiency

  4. 15/06/2005 Solar Wind 11/SOHO 16 1 Radial Dependence of Solar

    E-print Network

    Kallenrode, May-Britt

    15/06/2005 Solar Wind 11/SOHO 16 1 Radial Dependence of Solar Energetic Particle Events M.-B. Kallenrode #12;15/06/2005 Solar Wind 11/SOHO 16 2 Outline No discussion about composition and charge states spectra) #12;15/06/2005 Solar Wind 11/SOHO 16 3 Propagation of a delta-pulse Delta-pulse gives Green

  5. Solar wind electron temperature and density measurements on the Solar Orbiter with thermal noise spectroscopy

    E-print Network

    California at Berkeley, University of

    for the internal energy transport in the corona and the solar wind. The measurement of the electron temperature (TeSolar wind electron temperature and density measurements on the Solar Orbiter with thermal noise Abstract The measurement of the solar wind electron temperature in the unexplored region between 1 and 45

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

    SciTech Connect

    Reisenfeld, D. B. (Daniel B.); Wiens, R. C. (Roger C.); Barraclough, B. L.; Steinberg, J. T (John T.); Dekoning, C. A. (Curt A.); Zurbuchen, T. H. (Thomas H.); Burnett, D. S. (Donald 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 regime-specific collectors (CH, IS, or CME) was exposed to the solar wind. Here we report on the regime-specific solar wind conditions from in-situ instruments over the course of the collection period. Further, we use composition data from the SWICS (Solar Wind Ion Composition Spectrometer) instrument on ACE (McComas et al., 1998) to examine the FIP fractionation between solar wind regimes, and make a preliminary comparison of these to the FIP analysis of Ulysses/SWICS composition data (von Steiger et al. 2000). Our elemental fractionation study includes a reevaluation of the Ulysses FIP analysis in light of newly reported photospheric abundance data (Asplund, Grevesse & Sauval, 2005). The new abundance data indicate a metallicity (Z/X) for the Sun almost a factor of two lower than that reported in the widely used compilation of Anders & Grevesse (1989). The new photospheric abundances suggest a lower degree of solar wind fractionation than previously reported by von Steiger et al. (2000) for the first Ulysses polar orbit (1991-1998).

  7. The relation of open magnetic structures to solar wind flow

    NASA Technical Reports Server (NTRS)

    Levine, R. H.

    1978-01-01

    A study has been made of solar wind observations and models of the low-coronal magnetic field of the sun during the Skylab mission. Potential sources of solar wind plasma have been identified and in most cases systematically associated with observed solar wind flow features. The study pinpoints the problems of associating significant portions of the observed solar wind with sources outside coronal holes, although such associations are strongly suggested by the models. The phenomenological relationship between observed high solar wind speed at 1 AU and small coronal field divergence near the sun is examined and found to be well established but causally inconclusive in light of models of the outer heliosphere.

  8. Solar wind theory and modeling

    Microsoft Academic Search

    Viggo H. Hansteen

    1996-01-01

    tending out to eight solar radii. Be showed that the electron density profile determined by Baumbach [1937] is consistent with an electron-proton corona with a temperature of around a million degrees. The idea of a hot corona was gradually accepted, and mechanisms for heating the corona were suggested by Biermann [1946, 1948], Alfvgn [1947], and Schwarzschild [1948]. Chapman [1957] constructed

  9. 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.

  10. Do solar wind dynamic pressure impulses stimulate cavity modes?

    NASA Astrophysics Data System (ADS)

    Kepko, E.; Angelopoulos, V.

    2012-12-01

    Solar wind shocks and discontinuities are a source of broadband compressional power to the magnetosphere. It is often thought that this source of compressional energy stimulates global magnetospheric cavity modes, with frequencies determined by the internal properties of the magnetosphere. We present a THEMIS/ARTEMIS observation of a sharp solar wind discontinuity, with a factor of 3 increase in the solar wind dynamic pressure increase. The solar wind plasma immediately downstream of the discontinuity exhibited oscillations in the dynamic pressure with a period of ~10 minutes. Wind, located far upstream, also observed these oscillations. This event allows us to examine the periodic solar wind structure at widely separated points in the solar wind, to determine their evolution and scale-size. These oscillations in the solar wind dynamic pressure appeared to drive magnetospheric oscillations at the same period. In this case, and others that we will show, the source of discrete magnetospheric oscillations was not a cavity mode driven by the sudden dynamic pressure increase. Rather, even though the solar wind contained a sharp dynamic pressure increase, the magnetospheric oscillations appeared to be directly driven by highly periodic solar wind oscillations. We conclude by comparing evidence for in situ vs. solar atmosphere generation of the periodic solar wind density structures.

  11. ELECTRON PROPERTIES AND COULOMB COLLISIONS IN THE SOLAR WIND AT 1 AU: WIND OBSERVATIONS

    E-print Network

    California at Berkeley, University of

    ELECTRON PROPERTIES AND COULOMB COLLISIONS IN THE SOLAR WIND AT 1 AU: WIND OBSERVATIONS C. Salem,1 the electron properties of the solar wind observed by the Wind satellite at 1 AU in the ecliptic plane, during, in favor of a regulation of the heat flux by Coulomb collisions. The observed heat flux is then compared

  12. The solar wind as deduced from lunar samples

    NASA Technical Reports Server (NTRS)

    Eberhardt, P.

    1974-01-01

    Lunar surface samples, which have been exposed to the solar wind, can be used to obtain information on the recent and past solar wind. Some of the more important conclusions reached are: The D/H ratio in the solar wind is smaller than 0.000003. The isotopic composition of C, Ar (except Ar-40), and Kr in the solar wind and on the earth are the same within approximately plus or minus 3%. Terrestrial Ne is enriched in the heavier isotopes relative to solar wind Ne. The average solar wind flux in the past was probably higher than at present. The average solar wind energy has varied in the past; however, no long time trend is apparent. Evidence for a secular decrease of the He-4/He-3 ratio with time exists.

  13. Fast solar wind measurements from the Bright Monitor of the Solar Wind instrument on Spektr-R

    NASA Astrophysics Data System (ADS)

    Zerbo, J. L.; Safrankova, J.; Nemecek, Z.; Zastenker, G. N.; Kasper, J. C.; Stevens, M. L.; Richardson, J. D.

    2014-12-01

    Fast solar wind measurements from the Bright Monitor of the Solar Wind instrumentonboard the Spektr-R spacecraft are presented. This instrument measures plasmaparameters with time resolution as high as 30 ms. These measurements provide a preview of what the fast Faraday cup detectors on Triana and Solar Probe Plus will observe. We will compare solar wind structures observed at Spektr-R at high time-resolution with lower cadence observations from Wind. We will describe the small-scale plasma parameters in these solar wind structures.

  14. Composition of quasi-stationary solar wind flows from Ulysses/Solar Wind Ion Composition Spectrometer

    NASA Astrophysics Data System (ADS)

    von Steiger, R.; Schwadron, N. A.; Fisk, L. A.; Geiss, J.; Gloeckler, G.; Hefti, S.; Wilken, B.; Wimmer-Schweingruber, R. F.; Zurbuchen, T. H.

    2000-12-01

    Using improved, self-consistent analysis techniques, we determine the average solar wind charge state and elemental composition of nearly 40 ion species of He, C, N, O, Ne, Mg, Si, S, and Fe observed with the Solar Wind Ion Composition Spectrometer on Ulysses. We compare results obtained during selected time periods, including both slow solar wind and fast streams, concentrating on the quasi-stationary flows away from recurrent or intermittent disturbances such as corotating interaction regions or coronal mass ejections. In the fast streams the charge state distributions are consistent with a single freezing-in temperature for each element, whereas in the slow wind these distributions appear to be composed of contributions from a range of temperatures. The elemental composition shows the well-known first ionization potential (FIP) bias of the solar wind composition with respect to the photosphere. However, it appears that our average enrichment factor of low-FIP elements in the slow wind, not quite a factor of 3, is smaller than that in previous compilations. In fast streams the FIP bias is found to be yet smaller but still significantly above 1, clearly indicating that the FIP fractionation effect is also active beneath coronal holes from where the fast wind originates. This imposes basic requirements upon FIP fractionation models, which should reproduce the stronger and more variable low-FIP bias in the slow wind and a weaker (and perhaps conceptually different) low-FIP bias in fast streams. Taken together, these results firmly establish the fundamental difference between the two quasi-stationary solar wind types.

  15. A Semiempirical Magnetohydrodynamical Model of the Solar Wind

    Microsoft Academic Search

    O. Cohen; I. V. Sokolov; I. I. Roussev; C. N. Arge; W. B. Manchester; T. I. Gombosi; R. A. Frazin; F. Kamalabadi; M. Velli

    2007-01-01

    We present a new MHD model for simulating the large-scale structure of the solar corona and solar wind under ``steady state'' conditions stemming from the Wang-Sheeley-Arge empirical model. The processes of turbulent heating in the solar wind are parameterized using a phenomenological, thermodynamical model with a varied polytropic index. We employ the Bernoulli integral to bridge the asymptotic solar wind

  16. The Solar Wind in the Outer Heliosphere at Solar John D. Richardson and Chi Wang

    E-print Network

    Richardson, John

    The Solar Wind in the Outer Heliosphere at Solar Maximum John D. Richardson and Chi Wang Center solar wind observations in the outer heliosphere, concentrating on the recent data near solar maximum. The speed and temperature tend to be lower at solar maximum, due to the lack of coronal holes. The near

  17. 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. PMID:24996092

  18. Solar cycle dependence of solar wind energy coupling to the thermosphere

    Microsoft Academic Search

    William J. Burke

    2011-01-01

    Efficient solar wind energy coupling to storm time thermosphere depends on F10.7Estimates storm time energy partitioning between thermosphere and ring currentMethod adapts to specify solar wind\\/thermosphere energy coupling during storms

  19. Acceleration of the Solar Wind Ions

    Microsoft Academic Search

    V. L. Shevchenko; V. L. Galinsky; M. V. Medvedev; S. K. Ride; R. Z. Sagdeev

    1999-01-01

    In situ observations of the solar wind revealed that helium ion bulk speed nu_alpha considerable exceed the proton speed nu_p, it was found that differential speed Deltanu_alpha p is close to the local Alfven speed nu_A, and remarkably well aligned with interplanetary magnetic field. We investigate the mechanism of preferential acceleration of heavy ions connected with their resonant cyclotron interaction

  20. Magnetospheric feedbacks in solar wind energy transfer

    Microsoft Academic Search

    Minna Palmroth; Tuija I. Pulkkinen; Chandrasekhar R. Anekallu; Ilja Honkonen; Hannu E. J. Koskinen; Elizabeth A. Lucek; Iannis Dandouras

    2010-01-01

    The solar wind kinetic energy, fueling all dynamical processes within the near-Earth space, is extracted by a dynamo process at the magnetopause converting kinetic energy into magnetic energy. We investigate the magnetopause energy transfer both in small and large scales; using Cluster observations as well as a three-dimensional global magnetohydrodynamic (MHD) simulation GUMICS-4. In the simulation, the spatial distribution of

  1. Mercury Sodium Atmosphere, Magnetosphere and Solar Wind

    Microsoft Academic Search

    R. M. Killen; B. Giles; A. E. Potter; B. V. Jackson; J. Linker; Z. Mikic

    1999-01-01

    Earth-based observations of Mercury's sodium atmosphere have revealed large-scale spatial variations and rapid temporal variations (e.g. Potter and Morgan, Adv. Space Res. 19, 1571, 1997; Potter, A.E. et al., Planet. Space. Sci., In press, 1999). We show how the observed brightness variations may be related to the topology of Mercury's magnetosphere in response to solar wind variations at Mercury's orbit.

  2. Mirror Mode Structures in the Solar Wind

    Microsoft Academic Search

    V. Wong; W. Horton; T. H. Watanabe; H. Sugama

    2003-01-01

    High thermal particle pressure-to-magnetic pressure ratio plasmas, called high-beta plasmas, are ubiquitous in space science. Often the energization processes such as cross-field compression leads to temperature anisotropies Tperpendicular to \\/T_\\\\|>1 that drive the mirror instability. For the nonuniform magnetic field, as in the solar wind, the critical value of the temperature anisotropy (Tperpendicular to \\/T_\\\\|)_ crit is calculated as a

  3. Turbulence and waves in the solar wind

    SciTech Connect

    Roberts, D.A.; Goldstein, M.L. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    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.

  4. Automated classification of solar wind disturbances

    NASA Astrophysics Data System (ADS)

    Vennerstrom, Susanne; Leer, Kristoffer

    2015-04-01

    Geomagnetic storms are known to be caused by solar wind disturbances associated with the passage of either interplanetary coronal mass ejections (ICMEs) or stream interaction regions (SIRs) associated with high-speed streams from coronal holes. We present and assess a new method for automated detection and subsequent classification of solar wind disturbances arriving at L1. The method requires solar wind in situ plasma and magnetic field observations, currently provided in near real-time by NOAA/NASA from the ACE SWEPAM and MAG instruments. Periods of significantly enhanced magnetic field are identified and classified according to their most likely cause, being either ICMEs or high speed streams creating stream interaction regions SIRs. In the output the disturbed intervals are thus classified either as "ICME"-related, "SIR"-related or "NO ID". We compare the results statistically with existing lists of ICMEs and SIRs derived manually, and assess the usefulness of the service for providing early warnings of upcoming geomagnetic storms.

  5. Comparison of Solar Source Regions of LASCO Coronal Streamers and Solar Wind Sampled by ACE and Ulysses near Solar Maximum

    Microsoft Academic Search

    P. C. Liewer; M. Neugebauer; D. Biesecker; D. Socker

    2001-01-01

    The highly inclined and distorted current sheet seen during the current solar maximum leaves a strong imprint on the solar corona as seen by SOHO LASCO and the solar wind sector structure as seen by Ulysses and ACE. Here we present results of studies to determine the solar source regions of (1) solar wind streams sampled in situ by Ulysses

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

    Microsoft Academic Search

    Christina On-Yee Lee

    2010-01-01

    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

  7. Large-scale structure of the fast solar wind

    Microsoft Academic Search

    M. M. Bisi; R. A. Fallows; A. R. Breen; S. Rifai Habbal; R. A. Jones

    2007-01-01

    We present the results of a comprehensive study of the fast solar wind near solar minimum conditions using interplanetary scintillation (IPS) data taken with the EISCAT system in northern Scandinavia, and a recent extremely long baseline observation using both EISCAT and MERLIN systems. The results from IPS observations suggest that the fast wind inside 100 solar radii (R$\\\\odot$) can be

  8. 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.

  9. Effect of solar wind flow geometry on solar wind parameters at 1 AU for a low-frequency cascade driven solar wind

    Microsoft Academic Search

    C. J. Mountford; S. R. Habbal; X. Li

    2003-01-01

    A two-fluid, one-dimensional solar wind model is used to explore how the change in the expansion of a given flow tube with heliocentric distance influences the properties of the solar wind. Using a single driving mechanism, namely ion cyclotron resonance through a nonlinear Kolmogorov cascade process, for proton heating, the Alfvén wave amplitude, electron density, and temperature are kept fixed

  10. The Rising Phase of Solar Cycle 24: General Solar Wind, Large-Scale Solar Wind Structures, and Sector Asymmetry

    NASA Astrophysics Data System (ADS)

    Jian, L.; Russell, C. T.; Luhmann, J. G.; Riley, P.; Hoeksema, J. T.; Odstrcil, D.; Petrie, G. J.

    2011-12-01

    The solar polar field is presently nearing its reversal, suggesting the approach of solar maximum. However, the sunspot number, solar wind dynamic pressure, and IMF are still weak, similar to conditions in 1998 (the middle of last rising phase), suggesting a peculiar rising phase for Solar Cycle 24. In this presentation, following the study of solar minimum 23/24 in Jian et al. (2011), we first report the variations of solar wind parameters from the beginning of space era to present and compare the current rising phase with that of previous cycles. Secondly, based on our long-term study of large-scale solar wind structures, including interplanetary CMEs (ICMEs), stream interaction regions (SIRs), and their associated shocks at 1 AU from 1995 to present, we compare their properties in this rising phase with those of Cycle 23 and study their possible influence on geomagnetic activity. Thirdly, dividing the solar wind into positive (anti-sunward) and negative (sunward) sectors depending on the IMF polarity, we compare the solar wind parameters of the two polarity sectors from the beginning of Solar Cycle 21 to present. We note that an asymmetry between the two sectors exists for past cycles as reported by Hiltula and Mursula (2007) as well as Erdos and Balogh (2010). The sector asymmetry is more pronounced during the last solar minimum 23/24. Positive polarity solar wind is observed more often at 1 AU than negative polarity in Cycles 21 and 23 and less often in Cycle 22 and likely in this Cycle 24. Using the PFSS and MHD models, we can calculate the polarity distributions closer to the Sun, and they do not always agree with the observations. We closely examine several representative Carrington rotations to find out the reason. From 1-AU observations, the solar wind from the negative polarity sector (currently from northern hemisphere of the Sun) is found to be faster, hotter, and have a smaller proton density than the wind from the positive sector since 2009. This can affect the geomagnetic activity systematically. Comparing with the solar and coronal observations, we look for interpretations of the asymmetry.

  11. 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

  12. 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 [Institute for Geochemistry and Petrology, ETH Zurich, Clausiusstrasse 25, CH-8092 Zurich (Switzerland); Bochsler, Peter [Physikalisches Institut, Universitaet Bern, Sidlerstasse 5, CH-3012 Bern (Switzerland); McKeegan, Kevin D. [Department of Earth and Space Sciences, University of California Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, CA 90095-1567 (United States); Neugebauer, Marcia [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092 (United States); Reisenfeld, Daniel B. [Department of Physics and Astronomy, University of Montana, Missoula, MT 59812 (United States); Wiens, Roger C., E-mail: heber@ess.ucla.edu [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    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.

  13. 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.

  14. 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.

  15. Magnetospheric cavity modes driven by solar wind dynamic pressure fluctuations

    Microsoft Academic Search

    S. G. Claudepierre; M. Wiltberger; S. R. Elkington; W. Lotko; M. K. Hudson

    2009-01-01

    We present results from Lyon-Fedder-Mobarry (LFM) global, three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind-magnetosphere interaction. We use these simulations to investigate the role that solar wind dynamic pressure fluctuations play in the generation of magnetospheric ultra-low frequency (ULF) pulsations. The simulations presented in this study are driven with idealized solar wind input conditions. In four of the simulations, we

  16. The role of compressibility in solar wind plasma turbulence

    E-print Network

    Bogdan Hnat; Sandra C. Chapman; George Rowlands

    2004-11-30

    Incompressible Magnetohydrodynamics is often assumed to describe solar wind turbulence. We use extended self similarity to reveal scaling in structure functions of density fluctuations in the solar wind. Obtained scaling is then compared with that found in the inertial range of quantities identified as passive scalars in other turbulent systems. We find that these are not coincident. This implies that either solar wind turbulence is compressible, or that straightforward comparison of structure functions does not adequately capture its inertial range properties.

  17. Models of the Solar Wind Interaction with Local Interstellar Cloud

    E-print Network

    Vladislav V. Izmodenov

    2002-08-30

    This paper reviews the theoretical approaches and existing models of the solar wind interaction with the Local Interstellar Cloud (LIC). Models discussed take into account the multi-component nature of the solar wind and local interstellar medium. Basic results of the modeling and their possible applications to interpretation of space experiments are summarized. Open questions of global modeling of the solar wind/LIC interaction and future perspectives are discussed.

  18. 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.

  19. Development of three-dimensional magnetohydrodynamic model for solar corona and solar wind simulation

    Microsoft Academic Search

    Xingqiu Yuan; Larisa Trichtchenko; David Boteler

    2010-01-01

    Propagation of coronal mass ejections from solar surface to the Earth magnetosphere is strongly influenced by the conditions in solar corona and ambient solar wind. Thus, reliable simulation of the background solar wind is the primary task toward the development of numerical model for the transient events. In this paper we introduce a new numerical model which has been specifically

  20. Comparison of the solar wind energy input to the magnetosphere measured by Wind and Interball-1

    Microsoft Academic Search

    A. A. Petrukovich; S. I. Klimov; A. Lazarus; R. P Lepping

    2001-01-01

    Timely solar wind measurements are indispensable for space weather forecasts and magnetospheric studies, but solar wind variations detected by a distant spacecraft might be different from those actually hitting Earth's magnetosphere. To determine how important these differences can be for geophysical applications, we compared energy input to the magnetosphere which was simultaneously measured by the Wind and Interball-1 spacecraft at

  1. Differential Flow Between Solar Wind Protons and Alpha Particles: First WIND Observations

    E-print Network

    Richardson, John

    made using the SWE Faraday cup detectors on the WIND p spacecraft are reported. Some overall trends solar wind. e e SWE includes two Faraday cup detectors for measuring th nergy-per-charge spectrum of solar wind protons and alpha - u particles [Ogilvie et al., 1995]. The Faraday cups provide meas rements

  2. Fast solar wind after the rapid acceleration

    NASA Astrophysics Data System (ADS)

    Kojima, M.; Breen, A. R.; Fujiki, K.; Hayashi, K.; Ohmi, T.; Tokumaru, M.

    2004-04-01

    We have studied the radial dependence of the velocity of high-latitude fast solar wind in the heliocentric distance range of 0.13-0.9 AU. For this study a new tomographic analysis method which can evaluate uncertainties was developed to obtain velocity distribution maps on two reference spheres at 0.13 and 0.3 AU using interplanetary scintillation (IPS) observations. First of all, it is tested that this tomographic method has enough sensitivity and reliability to investigate the radial dependence of the wind velocity. The analysis was made for the IPS observations during 3 years, from 1995 to 1997, when solar activity was minimum. From this analysis, average velocities of 770-780 km s-1 were obtained at distances of 0.13-0.3 AU, which were 19 ± 17 km s-1 lower than those at 0.3-0.9 AU. The results from this work, taken together with measurements of SOHO/LASCO, EISCAT and MERLIN [, 2002], Helios [, 1978], and Ulysses [, 2000], indicate that the fast wind is accelerated almost to its final flow velocity within 20 Rs and a small but not negligible acceleration exists beyond 30 Rs which tends to become smaller at farther heliocentric distances.

  3. Reception of real-time solar wind data at NICT

    NASA Astrophysics Data System (ADS)

    Watari, Shinichi; Ishii, Mamoru; Kubo, Yuki

    National Institute of Information and Communications Technology (NICT) has contributed reception of real-time solar wind data from Advanced Composition Explorer (ACE) since 1997. ACE has made in-situ solar wind observations at L1 point and has provided the data in real-time. The data is useful for warnings of geomagnetic storms up to one hour in advance. We renewed our antenna system for real-time solar wind data considering Deep Space Climate Observatory (DSCOVR), which follows on mission of ACE. In our presentation, we will report on our new antenna system and our application of solar wind data in Japanese space weather center.

  4. Solar Wind: Manifestations of Solar Activity E N CYC LO PE D IA O F AS T R O N O MY AN D AS T R O PHYS I C S Solar Wind: Manifestations of Solar

    E-print Network

    Webb, David F.

    Solar Wind: Manifestations of Solar Activity E N CYC LO PE D IA O F AS T R O N O MY AN D AS T R O PHYS I C S Solar Wind: Manifestations of Solar Activity The Sun's outer atmosphere, the corona, is continually heated and expands to create the solar wind. Solar activity waxes and wanes with the 11 yr cycle

  5. Improved forecasts of solar wind parameters using the Kalman filter

    Microsoft Academic Search

    M. E. Innocenti; G. Lapenta; B. Vrsnak; F. Crespon; C. Skandrani; M. Temmer; A. Veronig; L. Bettarini; S. Markidis; M. Skender

    2011-01-01

    A Kalman filter technique is applied to an empirical solar wind forecast modelWith KF, the forecasting errors decrease and the applicability period increasesKF grants to the model some robustness againt transient solar activity

  6. The multifluid character of the solar wind termination shock explaining the downstream supersonic solar wind ion flow

    Microsoft Academic Search

    Sergei V. Chalov; Hans J. Fahr

    2010-01-01

    The Voyager-2 observations at the recent crossing of the solar wind termination shock show that the downstream thermal protons still move with supersonic speed. Obviously it is due to their inefficient shock-heating and that the surpathermal ions absorb most of the upstream kinetic solar wind energy. In this paper we present a three-fluid approach of the solar wind plasma consisting

  7. Solar wind turbulence: anisotropy, anisotropy, anisotropy!

    NASA Astrophysics Data System (ADS)

    Wicks, R.; Forman, M. A.; Summerlin, E. J.; Roberts, D. A.; Salem, C. S.

    2014-12-01

    Turbulence heats the solar wind as it expands away from the Sun, but where and how does heating of ions and electrons occur? In order to understand this we must first look at the fluctuations making up the cascade, the properties and anisotropies of which will determine whether ions or electrons are heated and whether field-parallel or -perpendicular heating will occur, all of which amounts to a lot of different anisotropies! With this in mind, we present a review of recent advances in the observation of plasma turbulence in the solar wind and comparison with simulations; which features of solar wind turbulence are well reproduced and which need to be captured better? The first anisotropy is that of the fluctuations making up the turbulent cascade itself, fluctuations are known to be highly transverse, meaning that the perpendicular magnetic field components are dominant over the field-parallel component. The second anisotropy is that of the scaling of amplitude towards smaller scales with steeper spectra parallel to the local magnetic field direction. Observations of the anisotropy of the full power spectral tensor will be discussed, in particular with reference to Alfvenic and pseudo-Alfvenic fluctuations (effectively two different polarizations of Alfven waves), the next step beyond the traditional "slab + 2D" approach to incompressible MHD turbulence. The third anisotropy is that of the ion and electron distributions. Both sets of charged particles frequently show non-Maxwellian distributions with higher temperatures found either perpendicular to or parallel to the magnetic field direction. Proton distributions often show beams and the heavier alpha particles are often hotter than the protons. Localized structures such as current sheets and magnetic discontinuities are shown to be sites of intense and anisotropic heating. Small scale fluctuations filling the space between such discontinuities may also dissipate energy into ions and electrons, either through electric fields intrinsic to the modes generated by the turbulence or through resonant or stochastic processes. Observations show that kinetic Alfven waves are the dominant mode.

  8. Solar wind: The solar wind and the Sun-Earth link

    Microsoft Academic Search

    Shadia Rifia Habbal; Richard Woo

    2004-01-01

    The solar wind fills the space between the Sun and its planets, shapes the planetary environments and the heliosphere, and comes to a screeching halt at the heliopause, the boundary with the interstellar medium. This tenuous medium is a fertile environment for exotic plasma processes, most of which are not fully understood. It also holds the intimate secrets of the

  9. ISEE-C solar wind plasma experiment

    NASA Technical Reports Server (NTRS)

    Bame, S. J.; Asbridge, J. R.; Felthauser, H. E.; Glore, J. P.; Hawk, H. L.; Chavez, J.

    1978-01-01

    Two 135 deg spherical section electrostatic analyzers furnish electron and ion measurements of the solar wind on ISEE-C. Each of these instruments utilizes a divided secondary emitter system to intercept the analyzed particles. Secondary electrons selected from all of the emitters simultaneously provide fast two-dimensional measurements of the particle fluxes integrated over polar angle; at a slower rate secondary electrons are successively selected from individual emitters to provide three-dimensional measurements. Speed of the ion measurements is increased by a factor of two by using an active proton peak tracking system to reduce the total range of energy per charge which has to be covered.

  10. ON THE ORIGIN OF MID-LATITUDE FAST WIND: CHALLENGING THE TWO-STATE SOLAR WIND PARADIGM

    E-print Network

    Stakhiv, Mark

    The bimodal paradigm of solar wind describes a slow solar wind situated near the heliospheric current sheet while a fast wind overexpands from the poles to fill in the remainder of the heliosphere. In this paper, we challenge ...

  11. ELECTRON TRANSPORT IN THE FAST SOLAR WIND

    SciTech Connect

    Smith, H. M.; Marsch, E. [Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau (Germany); Helander, P., E-mail: hakan.smith@ipp.mpg.de [Max-Planck-Institut fuer Plasmaphysik, Wendelsteinstrasse 1, 17491 Greifswald (Germany)

    2012-07-01

    The electron velocity distribution function is studied in the extended solar corona above coronal holes (i.e., the inner part of the fast solar wind) from the highly collisional corona close to the Sun to the weakly collisional regions farther out. The electron kinetic equation is solved with a finite-element method in velocity space using a linearized Fokker-Planck collision operator. The ion density and temperature profiles are assumed to be known and the electric field and electron temperature are determined self-consistently. The results show quantitatively how much lower the electron heat flux and the thermal force are than predicted by high-collisionality theory. The sensitivity of the particle and heat fluxes to the assumed ion temperature profile and the applied boundary condition at the boundary far from the Sun is also studied.

  12. Geomagnetic responses to the solar wind and to solar activity

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1974-01-01

    A unified overview of present knowledge of the geomagnetic response to the dynamic solar wind is reported. 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 frozen-in 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 merging model emphasizes the importance of the interplanetary magnetic field and especially the north-south component. The solar sector structure with its organized magnetic field and embeeded high speed plasma streams is identified as the source of recurrent geomagnetic disturbances while flare associated interplanetary shock waves are the source of most violet and sporadic geomagnetic storms.

  13. Solar wind driving of magnetospheric ULF waves: Field line resonances driven by dynamic pressure fluctuations

    E-print Network

    Solar wind driving of magnetospheric ULF waves: Field line resonances driven by dynamic pressure observational studies suggest that solar wind dynamic pressure fluctuations can drive magnetosphericFedderMobarry (LFM) global, threedimensional magnetohydrodynamic (MHD) simulations of the solar wind

  14. Solar wind velocity and temperature in the outer heliosphere

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  15. Solar Wind Acceleration in Coronal Holes

    E-print Network

    Steven R. Cranmer

    2002-09-16

    This paper reviews the current state of our understanding of high-speed solar wind acceleration in coronal holes. Observations by SOHO, coupled with interplanetary particle measurements going back several decades, have put strong constraints on possible explanations for how the protons, electrons, and minor ions receive their extreme kinetic properties. The asymptotic plasma conditions of the wind depend on energy and momentum deposition both at the coronal base (where, e.g., the mass flux is determined) and in the extended acceleration region between 2 and 10 solar radii (where the plasma becomes collisionless and individual particle species begin to exhibit non-Maxwellian velocity distributions with different moments). The dissipation of magnetohydrodynamic fluctuations (i.e., waves, turbulence, and shocks) is believed to dominate the heating in the extended corona, and spectroscopic observations from the UVCS instrument on SOHO have helped to narrow the field of possibilities for the precise modes, generation mechanisms, and damping channels. We will survey recent theoretical and observational results that have contributed to new insights, and we will also show how next-generation instruments can be designed to identify and characterize the dominant physical processes to an unprecedented degree.

  16. Velocity shear generation of solar wind turbulence

    SciTech Connect

    Roberts, D.A.; Goldstein, M.L.; Ghosh, S. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Matthaeus, W.H. [Univ. of Delaware, Newark, DE (United States)

    1992-11-01

    The authors use a two-dimensional, incompressible MHD spectral code to establish that shear-driven turbulence is a possible means for producing many observed properties of the evolution of the magnetic and velocity fluctuations in the solar wind and, in particular, the evolution of the cross helicity ({open_quotes}Alfvenicity{close_quotes}) at small scales. They find that large-scale shear can nonlinearly produce a cascade to smaller scale fluctuations even when the linear Kelvin-Helmholtz mode is stable and that a roughly power law inertial range is established by this process. While the fluctuations thus produced are not Alfvenic, they are nearly equipartitioned between magnetic and kinetic energy. The authors report simulations with Alfvenic fluctuations at high wave numbers, both with and without shear layers and find that it is the low cross helicity at low wave numbers that is critical to the cross helicity evolution, rather than the geometry of the flow or the dominance of kinetic energy at large scales. The fluctuations produced by shear effects are shown to evolve similarly but more slowly in the presence of a larger mean field and to be anisotropic with a preferred direction of spectral transfer perpendicular to the mean field. The evolution found is similar to that seen in some other simulations of HMD turbulence, and thus seems in many respects to be an instance of a more generic turbulent evolution rather than due to specific conditions in the solar wind. 75 refs., 18 figs.

  17. 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.

  18. New Insights into Solar Wind Physics from SOHO

    E-print Network

    Steven R. Cranmer

    2004-09-10

    The Solar and Heliospheric Observatory (SOHO) was launched in December 1995 with a suite of instruments designed to answer long-standing questions about the Sun's internal structure, its extensive outer atmosphere, and the solar wind. This paper reviews the new understanding of the physical processes responsible for the solar wind that have come from the past 8 years of SOHO observations, analysis, and theoretical work. For example, the UVCS instrument on SOHO has revealed the acceleration region of the fast solar wind to be far from simple thermal equilibrium. Evidence for preferential acceleration of ions, 100 million K ion temperatures, and marked departures from Maxwellian velocity distributions all point to specific types of collisionless heating processes. The slow solar wind, typically associated with bright helmet streamers, has been found to share some of the nonthermal characteristics of the fast wind. Abundance measurements from spectroscopy and visible-light coronagraphic movies from LASCO have led to a better census of the plasma components making up the slow wind. The origins of the solar wind in the photosphere and chromosphere have been better elucidated with disk spectroscopy from the SUMER and CDS instruments. Finally, the impact of the solar wind on spacecraft systems, ground-based technology, and astronauts has been greatly aided by having continuous solar observations at the Earth-Sun L1 point, and SOHO has set a strong precedent for future studies of space weather.

  19. Response of Saturn's Magnetosphere and Ionosphere to Solar Wind Driving

    Microsoft Academic Search

    K. C. Hansen; B. Zieger; J. T. Clarke; T. I. Gombosi; G. B. Hospodarsky; W. S. Kurth; J. D. Nichols

    2008-01-01

    The extent to which the solar wind drives Saturn's magnetosphere-ionosphere system is an ongoing topic of extensive study due to both the Cassini spacecraft presence in the Saturnian system as well as the recent (2007, 2008) Hubble Space Telescope campaign to image the UV aurora. Studies using these data have shown some evidence that solar wind dynamic pressure enhancements influence

  20. The Interaction between the Solar Wind and the Earth's Magnetosphere

    Microsoft Academic Search

    W. I. Axford

    1962-01-01

    It is argued in this note that the interplanetary gas causefully be treated as a continuum as far as the interaction between the solar wind and the terrestrial magnestosphere is concerned. On this basis, since the solar wind is highly supersonic near the earth, a collision- free bow shock wave should be a permanent feature of iaterplanetary space on the

  1. Solar wind control of the magnetopause shape, location, and motion

    Microsoft Academic Search

    D. G. Sibeck; R. E. Lopez; E. C. Roelof

    1991-01-01

    The authors have assembled a data set of 1,821 magnetopause crossings. Separate fits to subsets of this data set determine the magnetopause location as a function of solar wind dynamic pressure and interplanetary magnetic field operation. Solar wind dynamic pressure variations produce self-similar magnetopause motion on time scales of one hour or longer. They verify the pressure balance relationship between

  2. Hybrid solar-wind energy conversion systems meteorological aspects

    Microsoft Academic Search

    C. I. Aspliden

    1981-01-01

    Both the solar and wind resources available in the boundary layer vary in time and space. Data indicate, however, that the availability of the two resources may complement each other on both short and long term bases in many regions to meet different load requirements in various applications. This suggests that solar-wind hybrid systems may be more attractive and suitable

  3. INTERACTION OF THE SOLAR WIND WITH PLANETARY ATMOSPHERES

    Microsoft Academic Search

    Richard A. Elco

    1969-01-01

    Neither Venus nor the moon have a significant dipole magnetic field, and their atmospheres are exposed to the solar wind and the interplanetary magnetic field. As the solar wind ions penetrate the atmosphere, photo and charge-exchange ionization reactions alter the density and velocity of the ion stream. A collisionless reacting hydromagnetic model is used to describe the flow of atmospheric

  4. Influence of the solar wind energy on the atmospheric processes

    Microsoft Academic Search

    M. Radovanovic; M. Stevancevic; D. Strbac

    2003-01-01

    After getting the first results from the satellite electromagnetic measures of parameters of the solar wind, it is noticed that under a certain conditions, the solar wind could have a very important influence on the atmospheric processes that is to say on the air masses moving. Satellite visual and infrared observations, as well as electromagnetic measures showed that the movements

  5. Interaction of ICMEs / MCs with the Solar Wind

    E-print Network

    University College London

    Interaction of ICMEs / MCs with the Solar Wind Pascal Démoulin CME solar wind flux rope magnetic structures , shocks ... Sun / Port shock ICME / boat A crude analogy #12;Large scale implications of MCs of MCs and ICMEs ( Zurbuchen & Richardson 2006 ) Definition of Magnetic Clouds : smooth & large rotation

  6. Saturn Kilometric Radiation as monitor for the solar wind ?

    Microsoft Academic Search

    H. O. Rucker; Cassini-Skr

    2006-01-01

    Since the Voyager mission it is known that the Saturn Kilometric Radiation SKR is strongly influenced by external forces i e the solar wind and in particular the solar wind ram pressure Recent studies using Cassini data essentially confirmed these findings for particular periods during the first orbit of Cassini The data coverage of SKR by the Cassini RPWS experiment

  7. Solar and wind energy utilization in broiler production

    SciTech Connect

    Brinsfield, R.B.; Yaramanoglu, M.; Wheaton, F.

    1984-01-01

    Available solar and wind energy and both the electrical and thermal energy demand of a typical broiler facility were mathematically modeled based on 10 years of weather data for Salisbury, Maryland. The available energy was then compared with the broiler facility demands as a means of sizing solar and wind energy collection equipment to meet the demands.

  8. The Plasma Magnet for Sailing the Solar Wind

    Microsoft Academic Search

    John Slough

    2005-01-01

    Plasma sail propulsion based on the plasma magnet is a unique system that taps the ambient energy of the solar wind with minimal energy and mass requirements. The coupling to the solar wind is made through the generation of a large-scale (~> 30 km) dipolar magnetic field. Unlike the original magnetic sail concept, the coil currents are conducted in a

  9. On WKB expansions for Alfven waves in the solar wind

    NASA Technical Reports Server (NTRS)

    Hollweg, Joseph V.

    1990-01-01

    The WKB expansion for 'toroidal' Alfven waves in solar wind, which is described by equations of Heinemann and Olbert (1980), is examined. In this case, the multiple scales method (Nayfeh, 1981) is used to obtain a uniform expansion. It is shown that the WKB expansion used by Belcher (1971) and Hollweg (1973) for Alfven waves in the solar wind is nonuniformly convergent.

  10. The solar wind interaction with the Earth's magnetosphere: a tutorial

    Microsoft Academic Search

    C.T. Russell

    2000-01-01

    The size of the terrestrial magnetosphere is determined by the balance between the solar wind dynamic pressure and the pressure exerted by the magnetosphere, principally that of its magnetic field. The shape of the magnetosphere is additionally influenced by the drag of the solar wind, or tangential stress, on the magnetosphere. This drag is predominantly caused by the mechanism known

  11. 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.

  12. Magnetohydrodynamic modeling of the solar wind in the outer heliosphere

    SciTech Connect

    Usmanov, A. V.; Goldstein, M. L.; Matthaeus, W. H. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Code 673, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States)

    2012-05-21

    We present initial results from a solar wind model that accounts for transport of turbulence and treats pickup protons as a separate fluid. The model is based on a numerical solution of the coupled set of mean-field Reynolds-averaged solar wind equations and small-scale turbulence transport equations in the region from 0.3-100 AU. The pickup protons are assumed to be comoving with the solar wind flow and described by separate mass and energy equations. The equations include the terms for energy transfer from pickup protons to solar wind protons and for the plasma heating by turbulent dissipation. The momentum equation contains a term that describes the loss of momentumby the solar wind flow due to the charge exchangewith the interstellar neutral hydrogen.

  13. OBSERVATION OF FLUX-TUBE CROSSINGS IN THE SOLAR WIND

    SciTech Connect

    Arnold, L.; Li, G.; Li, X. [Department of Physics and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)] [Department of Physics and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Yan, Y., E-mail: gang.li@uah.edu [Key Laboratory of Solar Activity, National Astronomical Observatories of Chinese Academy of Sciences, Beijing 100012 (China)

    2013-03-20

    Current sheets are ubiquitous in the solar wind. They are a major source of the solar wind MHD turbulence intermittency. They may result from nonlinear interactions of the solar wind MHD turbulence or are the boundaries of flux tubes that originate from the solar surface. Some current sheets appear in pairs and are the boundaries of transient structures such as magnetic holes and reconnection exhausts or the edges of pulsed Alfven waves. For an individual current sheet, discerning whether it is a flux-tube boundary or due to nonlinear interactions or the boundary of a transient structure is difficult. In this work, using data from the Wind spacecraft, we identify two three-current-sheet events. Detailed examination of these two events suggests that they are best explained by the flux-tube-crossing scenario. Our study provides convincing evidence supporting the scenario that the solar wind consists of flux tubes where distinct plasmas reside.

  14. 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.

  15. Solar wind iron charge states preceding a driver plasma

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Ipavich, F. M.; Gloeckler, G.; Hovestadt, D.; Tsurutani, B. T.

    1987-01-01

    Iron and silicon/sulfur charge state and velocity measurements and iron density measurements in the shocked solar wind which preceded the flare-related driver plasma observed on September 29, 1978 by ISEE 3 are reported. Given the assumption that the driver plasma is magnetically isolated from the ambient solar wind, the contact surface separating these two plasma regimes is expected to form an distinct boundary in the charge state composition. Instead, an apparent transition in the ionization state of the shocked solar wind from ambient solar wind values to those typical of the driver plasma is observed. This result may reflect X-ray ionization of the solar wind plasma near the flare site.

  16. 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.

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

    SciTech Connect

    Šafránková, J.; N?me?ek, Z.; Cagaš, P.; P?ech, L.; Pavl?, J. [Faculty of Mathematics and Physics, Charles University, V Holešovi?kách 2, 18000 Prague 8 (Czech Republic); Zastenker, G. N.; Riazantseva, M. O.; Koloskova, I. V., E-mail: jana.safrankova@mff.cuni.cz [Space Research Institute of Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow 117997 (Russian Federation)

    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.

  18. Solar wind flows associated with hot heavy ions

    NASA Technical Reports Server (NTRS)

    Fenimore, E. E.

    1980-01-01

    Solar wind heavy ion spectra measured with the Vela instrumentation are studied to determine the solar origins of various solar wind structures which contain anomalously high ionization states. The spectra indicating hot coronal conditions were found to occur in 1/7th of all measurements and almost exclusively in postshock flows, nonshock related helium abundance enhancements, or noncompressive density enhancements. The observation of several flared-related helium abundance enhancements suggests that the flare-heated plasma can evolve into the solar wind without producing a noticeable shock at 1 AU.

  19. Radial evolution of the solar wind speed as one source of alpha to proton ratio variations

    Microsoft Academic Search

    S. L. McGregor; W. Hughes; J. C. Kasper; C. N. Arge

    2009-01-01

    The relative abundance of alphas to protons in the solar wind varies with solar wind speed and on solar cycle time scales. However, the WSA-Enlil model shows significant stream interactions and solar wind velocity evolution within a few tenths of an AU of the sun, resulting in solar wind speeds observed at 1.0 AU and beyond which can be very

  20. A two-fluid model for the solar wind

    Microsoft Academic Search

    S. Massaglia

    1993-01-01

    We present a two-fluid model of the solar wind, treating, under stationary conditions, the wind acceleration and the coronal heating simultaneously as a single problem. Our aim is to construct a scheme for the solution of the wind equations that can be readily adapted to different boundary conditions and also different heating and acceleration mechanisms. The method developed is applied

  1. Solar cycle evolution of the solar wind speed distribution from 1985 to 2008

    Microsoft Academic Search

    Munetoshi Tokumaru; Masayoshi Kojima; Ken'ichi Fujiki

    2010-01-01

    The evolution of solar wind speed distribution during the period 1985–2008, which covers two solar cycles (22 and 23), has been investigated using multistation interplanetary scintillation (IPS) measurements at 327 MHz. The results obtained here clearly demonstrate that fast (slow) wind areas increase (decrease) systematically as the solar activity diminishes, reaching the maximum (minimum) value at the minimum phase. The

  2. A Three-dimensional Model of the Solar Wind Incorporating Solar Magnetogram Observations

    Microsoft Academic Search

    I. I. Roussev; T. I. Gombosi; I. V. Sokolov; M. Velli; W. Manchester IV; D. L. DeZeeuw; P. Liewer; G. Tóth; J. Luhmann

    2003-01-01

    We present a new compressible MHD model for simulating the three-dimensional structure of the solar wind under steady state conditions. The initial potential magnetic field is reconstructed throughout the computational volume using the source surface method, in which the necessary boundary conditions for the field are provided by solar magnetogram data. The solar wind in our simulations is powered by

  3. Forms of Eulerian correlation functions in the solar wind

    E-print Network

    A. Shalchi

    2008-09-07

    Current spacecraft missions such as Wind and ACE can be used to determine magnetic correlation functions in the solar wind. Data sets from these missions can, in principle, also be used to compute so-called Eulerian correlation functions. These temporal correlations are essential for understanding the dynamics of solar wind turbulence. In the current article we calculate these dynamical correlations by using well-established methods. These results are very useful for a comparison with Eulerian correlations obtained from space craft missions.

  4. Nature of the Solar Wind Electron Distribution Functions in the Slow and Fast Solar Wind at 1 AU

    Microsoft Academic Search

    C. Salem; D. Hubert; S. Bale; D. Larson; B. Lin

    2004-01-01

    The non equilibrium characteristics of the solar wind electron distribution functions (EDF) at 1 AU are of great importance in many aspects, for instance in understanding heat conduction, plasma microinstabilities and transport in weakly collisional plasma, as well as in the scenario at the origin of the solar wind. It has been known for a long time that, in the

  5. Simulation and optimum design of hybrid solar-wind and solar-wind-diesel power generation systems

    Microsoft Academic Search

    Wei Zhou

    2008-01-01

    Solar and wind energy systems are considered as promising power generating sources due to its availability and topological advantages in local power generations. However, a drawback, common to solar and wind options, is their unpredictable nature and dependence on weather changes, both of these energy systems would have to be oversized to make them completely reliable. Fortunately, the problems caused

  6. Tracking the Solar Wind Event to Its Source

    NSDL National Science Digital Library

    This is an activity about cause and effect. Learners will calculate the approximate travel time of each solar wind event identified in the previous activity in this set to estimate the time at which the disturbance would have left the Sun. Then, they will examine solar images in an attempt to identify the event on the Sun that may have caused the specific solar wind episode. This is Activity 12 of the Space Weather Forecast curriculum.

  7. Mobile solar and wind-powered generator (MSWPG)

    Microsoft Academic Search

    W. E. Alnaser

    1999-01-01

    We report an innovation that utilizes solar and wind energy in a compact and practical way. A mobile solar and wind-powered mobile generator that produces 1.5 kW has been designed and constructed at the University of Bahrain, in collaboration with Long International, Bahrain. The renewable-energy system was erected on a trailer and is self-contained. It contains 16 solar panels with

  8. Parametric study of hybrid (wind + solar + diesel) power generating systems

    Microsoft Academic Search

    M. A. Elhadidy; S. M. Shaahid

    2000-01-01

    The combined utilization of renewables such as solar and wind energy is becoming increasingly attractive and is being widely used for substitution of oil-produced energy, and eventually to reduce air pollution. In the present investigation, hourly wind-speed and solar radiation measurements made at the solar radiation and meteorological monitoring station, Dhahran (26°32?N, 50°13?E), Saudi Arabia, have been analyzed to study

  9. The Importance of Using Continuous Solar Inputs in 3D Models to Simulate the Distant Solar Wind and Heliosheath

    Microsoft Academic Search

    D. S. Intriligator; T. Detman; W. Sun; A. Rees; T. S. Horbury; C. Deehr; M. Dryer; C. D. Fry; J. Intriligator

    2007-01-01

    Solar transients and the background solar wind give rise to asymmetries in the distant solar wind and heliosheath. Entering continuous solar data into time-dependent, 3D models originating at the Sun is crucial for accurately characterizing the distant solar wind and the heliosheath. We employ our time-dependent, 3D MHD (magnetohydrodynamic) model the HHMS - the Hybrid Heliospheric Modeling System - to

  10. Latitudinal distribution of the solar wind properties in the low-and high-pressure regimes: Wind observations

    E-print Network

    Paris-Sud XI, Université de

    Latitudinal distribution of the solar wind properties in the low- and high-pressure regimes: Wind: 29 November 1999 / Revised: 27 March 2000 / Accepted: 6 April 2000 Abstract. The solar wind ®nd that the solar wind properties mainly depend on the modulus jkj. But they also depend on a local

  11. Solar energetic particle events in different types of solar wind

    SciTech Connect

    Kahler, S. W. [Air Force Research Laboratory, Space Vehicles Directorate, 3550 Aberdeen Avenue, Kirtland AFB, NM 87117 (United States); Vourlidas, A., E-mail: stephen.kahler@kirtland.af.mil [Space Sciences Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    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.

  12. 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.

  13. Solar Energetic Particle Events in Different Types of Solar Wind

    NASA Astrophysics Data System (ADS)

    Kahler, Stephen W.; Vourlidas, Angelos

    2014-06-01

    We examine statistically some properties of 96 20 MeV gradual solar energetic proton (SEP) events as a function of three different types of solar winds (SWs) as classified by Richardson and Cane (2012). Gradual SEP (E > 10 MeV) events are produced in shocks driven by fast (V > 900 km/s) and wide (W > 60 deg) coronal mass ejections (CMEs). We find no differences between transient and fast or slow SW streams for SEP 20-MeV 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.

  14. Solar Energetic Particle Events in Different Types of Solar Wind

    NASA Astrophysics Data System (ADS)

    Kahler, S. W.; Vourlidas, A.

    2014-08-01

    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-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.

  15. The Genesis Solar Wind Collection Mission: Current Status

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    The NASA Genesis spacecraft was launched August 8, 2001 on a mission to collect samples of solar wind for greater than or equal to 2 years and then return them to Earth in 2004. Detailed analyses of the solar wind ions implanted into high-purity collection substrates will subsequently be carried out in earth-based laboratories 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 implications of the solar oxygen isotopic composition have been discussed. A list of other isotopic and elemental measurement objectives, and some of the rationale behind them, is given.

  16. Solar-wind disturbances and the solar wind-magnetosphere energy coupling function

    Microsoft Academic Search

    S.-I. Akasofu

    1983-01-01

    Recent studies of the solar wind-magnetosphere interaction are reviewed in terms of the input-output relationship. We show that the magnetosphere is primarily a directly driven system and that the interaction constitutes a dynamo. As another important problem of the interaction, we examine the chain of processes by which the dynamo-generated power is transmitted to the polar ionosophere, leading to various

  17. The abundances of elements and isotopes in the solar wind

    SciTech Connect

    Gloeckler, G. (The Johns Hopkins University, Applied Physics Laboratory, Laurel, Maryland 20707, USA (USA)); Geiss, J. (Physikalisches Institut, University of Bern (Switzerland))

    1989-03-01

    Solar wind abundances have now been measured for eleven elements and the isotopes of the noble gases. The composition of all elements up to and including Ni, as well as most of their isotopes, should become known when new high-mass-resolution solar wind spectrometers are launched in the next decade. Aside from solar wind protons and alpha particles, which have been studied extensively since the 1960's, our information for heavier elements is limited. Nevertheless, two effects stand out. First is the enrichment of abundances of elements with low first ionizaiton potential (FIP), most likely the combined result of (a) an atom-ion separation process in the upper chromosphere, and (b) a marginal coupling of low-charge-state heavy ions to protons and alphas during the acceleration of the solar wind. Second, there is variability in the solar wind composition over a whole range of time scales. Recent measurements carried out in the Earth's magnetosheath during times that included high-speed coronal-hole-associated flows indicate a significantly lower overabundance of low FIP elements. Given the fact that the He/H ratio is remarkably constant in the coronal hole solar wind, this result suggests that both enrichment and variability are reduced in such flows. Studies by the ULYSSES spacecraft of the characteristics and composition of the least complicated solar wind, i.e., the flow emanating from the polar coronal holes, should significantly increase our understanding of coronal processes and solar wind acceleration. By combining these studies with measurements of the complete elemental and isotopic composition of the solar wind, we will be able to derive solar abundances for elements and isotopes that otherwise are poorly known.

  18. 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.

  19. 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.

  20. Intermittent turbulence in the solar wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1991-01-01

    This paper demonstrates the existence of intermittent turbulence in the solar wind at 8.5 AU. The pth-order velocity structure functions show scaling behavior in the range of periods from 0.85 hour to 13.6 hours for p of less than 20. The exponent of the scaling law s(p) is a quadratic function of p. These observations of s(p) for compressible MHD turbulence on a scale of the order of about 1 AU are consistent with laboratory measurements of s(p) for gasdynamic turbulence on a scale of the order of 1 m, indicating the universal character of intermittent turbulence. The observations are not described by the 'constant beta' model of intermittent turbulence. They are marginally consistent with the lognormal model. The observations are consistent with a random beta model prediction which assumes that the turbulence is a mixture of sheets and space-filling eddies.

  1. Interpretation of 3 He abundance variations in the solar wind

    Microsoft Academic Search

    M. A. Coplan; K. W. Ogilvie; P. Bochsler; J. Geiss

    1984-01-01

    The ion composition instrument (ICI) on ISEE-3 has observed the isotopes of helium of mass 3 and 4 in the solar wind almost continuously between August 1978 and July 1982. This period included the increase towards the maximum of solar activity cycle 21, the maximum period, and the beginning of the descent towards solar minimum. Observations were made when the

  2. Analysis of Wind Forces on Roof-Top Solar Panel

    NASA Astrophysics Data System (ADS)

    Panta, Yogendra; Kudav, Ganesh

    2011-03-01

    Structural loads on solar panels include forces due to high wind, gravity, thermal expansion, and earthquakes. International Building Code (IBC) and the American Society of Civil Engineers are two commonly used approaches in solar industries to address wind loads. Minimum Design Loads for Buildings and Other Structures (ASCE 7-02) can be used to calculate wind uplift loads on roof-mounted solar panels. The present study is primarily focused on 2D and 3D modeling with steady, and turbulent flow over an inclined solar panel on the flat based roof to predict the wind forces for designing wind management system. For the numerical simulation, 3-D incompressible flow with the standard k- ? was adopted and commercial CFD software ANSYS FLUENT was used. Results were then validated with wind tunnel experiments with a good agreement. Solar panels with various aspect ratios for various high wind speeds and angle of attacks were modeled and simulated in order to predict the wind loads in various scenarios. The present study concluded to reduce the strong wind uplift by designing a guide plate or a deflector before the panel. Acknowledgments to Northern States Metal Inc., OH (GK & YP) and School of Graduate Studies of YSU for RP & URC 2009-2010 (YP).

  3. Simulation of lunar carbon chemistry. I - Solar wind contribution

    NASA Technical Reports Server (NTRS)

    Bibring, J. P.; Chaumont, J.; Langevin, Y.; Maurette, M.; Burlingame, A. L.; Wszolek, P. C.

    1974-01-01

    Simulation experiments were conducted to identify the role of solar and lunar winds in the evolution of lunar carbon chemistry. Major conclusions are that (1) implantation of solar wind C, D, and N ions in silicates synthesizes small molecules that can be released into vacuum either by ion sputtering or by heating; (2) this synthesis is highly specific when compared to other processes accounting for the formation of molecules in the solar nebula or in interstellar space; (3) the carbon injected by the solar wind in the crystalline component of mature soils should reach a saturation concentration of about 200 ppm; and (4) the carbon chemistry of the crystalline component of mature soils is dominated by solar wind implantation effects.

  4. Simulation of period doubling of recurrent solar wind structures

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.; Burlaga, L. F.

    1990-01-01

    Based on satellite observations of a recurrent solar wind structure conducted in 1974, an MHD simulation model, and input functions generated from plasma and magnetic field data, the continuing evolution of the solar wind structure outside 5 AU is studied. The model uses the Rankine-Hugoniot relations to describe the jumps in flow properties across the shocks, and it treats shocks as surfaces of discontinuity with zero thickness. Two interaction processes (the collision and the merging of shocks) play important roles in restructuring the solar wind in the outer heliosphere. The simulation result shows that period doubling occurs between 5 and 10 AU. The recurrent solar wind appears to be a persistent new structure between 10 and 20 AU, and it consists of one merged interaction region per solar rotation.

  5. 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.

  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. PMID:18046399

  7. Solar Wind observations using the Mexican Array Radio Telescope (MEXART)

    NASA Astrophysics Data System (ADS)

    Romero-Hernandez, E.; Gonzalez-Esparza, A.; Villanueva, P.; Aguilar-Rodriguez, E.; Mejia-Ambriz, J. C.; Mexart

    2013-05-01

    The Mexican Array Radiotelescope (MEXART) is an instrument devoted to observations of radio sources to study large-scale structures in the solar wind employing the Interplanetary Scintillation (IPS) technique. We report recent IPS observations, from January to April of 2013, including an analysis of the scintillation index and the estimation of solar wind velocities for a set of radio sources. We track the first ICMEs registered by the MEXART. We are initiating a continuos operation for a complete monitoring of IPS radio sources that will complement solar wind studies based on in-situ observations.

  8. Quantifying shear-induced wave transformations in the solar wind

    E-print Network

    Grigol Gogoberidze; Andria Rogava; Stefaan Poedts

    2007-03-20

    The possibility of velocity shear-induced linear transformations of different magnetohydrodynamic waves in the solar wind is studied both analytically and numerically. A quantitative analysis of the wave transformation processes for all possible plasma-$\\beta$ regimes is performed. By applying the obtained criteria for effective wave coupling to the solar wind parameters, we show that velocity shear-induced linear transformations of Alfv\\'en waves into magneto-acoustic waves could effectively take place for the relatively low-frequency Alfv\\'en waves in the energy containing interval. The obtained results are in a good qualitative agreement with the observed features of density perturbations in the solar wind.

  9. Charge-exchange born He(+) ions in the solar wind

    NASA Astrophysics Data System (ADS)

    Gruntman, Michael A.

    1992-07-01

    The effect of charge transfer between solar wind alpha-particles and hydrogen atoms of interstellar origin is revisited. Singly-charged helium ions born in the charge transfer carry important information on processes in the solar wind and the heliosphere. The velocity distribution of such He(+) ions is substantially different from that of He(+) pick-up ions due to ionization of the interstellar helium atoms. Estimates of the expected abundances of the charge-exchange born He(+) in the solar wind are presented, and the possibility of measuring this plasma component on deep space missions is discussed.

  10. Wind loading on solar concentrators: some general considerations

    SciTech Connect

    Roschke, E. J.

    1984-05-01

    A survey has been 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. Wind loads, i.e., forces and moments, are proportional to the square of the mean wind velocity. Forces are proportional to the square of concentrator diameter, and moments are proportional to the cube of diameter. Thus, wind loads have an important bearing on size selection from both cost and performance standpoints. It is concluded that sufficient information exists so that reasonably accurate predictions of wind loading are possible for a given paraboloidal concentrator configuration, provided that reliable and relevant wind conditions are specified. Such predictions will be useful to the design engineer and to the systems engineer as well. Information is lacking, however, on wind effects in field arrays of paraboloidal concentrators. Wind tunnel tests have been performed on model heliostat arrays, but there are important aerodynamic differences between heliostats and paraboloidal dishes.

  11. Magnetohydrodynamic turbulence in the solar polar wind- comparing the last two solar minima

    Microsoft Academic Search

    S. C. Chapman; R. M. Nicol; E. Leonardis

    2010-01-01

    ULYSSES spacecraft solar polar passes at solar minimum provide in-situ observations of evolving MHD turbulence in the solar wind under ideal conditions of fast quiet flow. The recent unusually inactive solar minimum shows a decrease in the turbulent fluctuations of a factor of two in power in comparison with the previous minimum. We focus on two successive polar passes around

  12. Three-dimensional time-dependent MHD simulation model of the solar corona and solar wind

    Microsoft Academic Search

    K. Hayashi

    2006-01-01

    We will present the MHD simulation model for the solar corona and solar wind. The simulation utilizes the solar photospheric magnetic field measurement data as the boundary condition, and the obtained MHD solution is fully matching the given solar surface magnetic field distribution. In order that the simulated situation will be more realistic, the boundary treatment in our code is

  13. Solar-wind and solar-flare maturation of the lunar regolith

    NASA Technical Reports Server (NTRS)

    Bibring, J. P.; Borg, J.; Vassent, B.; Burlingame, A. L.; Langevin, Y.; Maurette, M.

    1975-01-01

    Detailed predictions concerning the depth and time-dependent accumulation of solar-wind effects and solar-flare tracks in lunar dust grains were obtained by use of an adaptation of a Monte Carlo soil-mixing computer code described by Duraud et al. (1975). The predictions are compared to experimental measurements obtained by analyzing lunar dust grains as well as artificially irradiated minerals by a variety of techniques. A study of amorphous coatings of solar-wind radiation-damaged material on certain lunar grains sets limits on the integrated residence time of these grains in the ancient solar wind. Other topics discussed include solar wind maturation, the peculiar shape of the experimental distribution of central track densities in 50-micron grains, and the interpretation of both track gradients in 50-micron feldspars and the relatively 'low' concentration of solar-wind species implanted in ilmenite grains.

  14. Solar Wind Turbulence A Study of Corotating Interaction Regions at 1 AU

    E-print Network

    Solar Wind Turbulence A Study of Corotating Interaction Regions at 1 AU Je rey A. Tessein Department of Physics University of New Hampshire Durham, NH 03824 May 15, 2009 #12;Abstract The solar wind's rotation and the variability in the source of the solar wind, fast moving wind can crash into slow wind

  15. Effects of solar wind dynamic pressure on the ionospheric fluence during the 31 August 2005 storm

    E-print Network

    Effects of solar wind dynamic pressure on the ionospheric O+ fluence during the 31 August 2005 solar wind data is contrasted against a case where the solar wind dynamic pressure (Pdyn with the solar wind dynamic pressure. Additionally, changes in Pdyn affect the downward Poynting flux only

  16. Are energetic electrons in the solar wind the source of the outer radiation belt?

    E-print Network

    Li, Xinlin

    Are energetic electrons in the solar wind the source of the outer radiation belt? Xinlin Li,1 D. N. Mewaldt6 Abstract. Using data from WIND, SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer the correlation of en- ergetic electrons in the 20-200 keV range in the solar wind and of high speed solar wind

  17. Radial Heliospheric Magnetic Fields in Solar Wind Rarefaction Regions: Ulysses Observations

    E-print Network

    Sanahuja, Blai

    Radial Heliospheric Magnetic Fields in Solar Wind Rarefaction Regions: Ulysses Observations D it observed solar wind shears from the incursions of high-latitude fast solar wind toward the low-latitude slow solar wind. We look for nearly radial field orientations commonly observed in rarefaction regions

  18. Utility scale hybrid wind–solar thermal electrical generation: A case study for Minnesota

    Microsoft Academic Search

    J. P. Reichling; F. A. Kulacki

    2008-01-01

    The performance of a hybrid wind–solar power plant in southwestern Minnesota is modeled for a 2-yr period using hourly wind and solar insolation data. The wind portion of the plant consists of four interconnected wind farms within a radius of 90km. The solar component of the plant is a parabolic trough solar thermal electric generating system using a heat transfer

  19. Coupling Between Chromosphere and Corona: Why it Matters for the Solar Wind

    Microsoft Academic Search

    Lie-Svendsen; V. H. Hansteen; E. Leer

    2001-01-01

    The solar wind is driven by energy input which must be deposited mainly in the corona. In some sense, therefore, the solar wind ``starts'' in the corona, and most solar wind models have their lower boundary here. However, the underlying chromosphere and transition region is not only a ``passive'' supplier of solar wind plasma. Energy must be supplied as well

  20. a Study on the Solar Wind Energy Input at Mercury and Earth Magnetospheres

    Microsoft Academic Search

    Ezequiel Echer

    2008-01-01

    The solar wind-magnetosphere energy coupling at Mercury and Earth magnetospheres is studied in this work. Using typical solar wind parameters at Mercury and Earth orbits, and assuming the magnetic reconnection mechanism, the energy input into these two planetary magnetospheres is calculated using the Akasofu's epsilon parameter. The energy input is calculated for varied solar wind conditions- solar wind speed, interplanetary

  1. Geomagnetic storms driven by ICME- and CIR-dominated solar wind

    Microsoft Academic Search

    M. H. Denton; J. E. Borovsky; R. M. Skoug; M. F. Thomsen; B. Lavraud; M. G. Henderson; R. L. McPherron; J. C. Zhang; M. W. Liemohn

    2006-01-01

    The interaction of the solar wind and the Earth's magnetosphere is complex and the phenomenology of the interaction is very different for solar wind dominated by interplanetary coronal mass ejections (ICMEs) compared to solar wind dominated by corotating interaction regions (CIRs). We perform a superposed epoch study of the effects of ICME- and CIR-dominated solar wind upon the storm-time plasma

  2. Saturn Kilometric Radiation as monitor for the solar wind ?

    NASA Astrophysics Data System (ADS)

    Rucker, H. O.; Cassini-Skr

    Since the Voyager mission it is known that the Saturn Kilometric Radiation SKR is strongly influenced by external forces i e the solar wind and in particular the solar wind ram pressure Recent studies using Cassini data essentially confirmed these findings for particular periods during the first orbit of Cassini The data coverage of SKR by the Cassini RPWS experiment for the period of six months prior to Saturn Orbit Insertion July 1 2004 is rather continuous whereas there are gaps in the solar wind plasma data The strong correlation of SKR with the solar wind may provide an indication on the variations of the solar wind plasma specifically during the gap periods The solar wind plasma data profile deduced from the SKR variations is compared with the Ulysses plasma data which have to be propagated over approx 4 AU applying ballistic and hydrodynamic propagation models The level of reliability of these models is given by using Wind SWE data propagated to the position of Ulysses and then compared with Ulysses SWOOP data First results will be presented

  3. Predicting solar and wind energy trends using cloud cover and wind velocity

    Microsoft Academic Search

    Brinsfield

    1981-01-01

    Developments include: (1) a mode to predict potential and clear sky solar radiation on a horizontal surface and clear sky solar radiation on a tilted panel for any latitude, POTSOL; (2) a model to predict solar radiation on a horizontal surface for any latitude as a function of total opaque cloud cover, ESR; and (3) a program to estimate wind

  4. Interpretation of He-3 abundance variations in the solar wind

    NASA Technical Reports Server (NTRS)

    Coplan, M. A.; Ogilvie, K. W.; Bochsler, P.; Geiss, J.

    1984-01-01

    The ion composition instrument (ICI) on ISEE-3 observed the isotopes of helium of mass 3 and 4 in the solar wind almost continuously between August 1978 and July 1982. This period included the increase towards the maximum of solar activity cycle 21, the maximum period, and the beginning of the descent towards solar minimum. Observations were made when the solar wind speed was between 300 and 620 km/s. For part of the period evidence for regular interplanetary magnetic sector structure was clear and a number of He-3 flares occurred during this time.

  5. Interpretation of 3He variations in the solar wind

    SciTech Connect

    Coplan, M.A.; Ogilvie, K.W.; Geiss, J.

    1983-06-01

    The ion composition instrument (ICI) on ISEE-3 observed the isotopes of helium of mass 3 and 4 in the solar wind almost continuously between August 1978 and July 1982. This period included the increase towards the maximum of solar activity cycle 21, the maximum period, and the beginning of the descent towards solar minimum. Observations were made when the solar wind speed was between 300 and 620 km/s. For part of the period evidence for regular interplanetary magnetic sector structure was clear and a number of 3He flares occurred during this time.

  6. Interpretation of 3He variations in the solar wind

    NASA Technical Reports Server (NTRS)

    Coplan, M. A.; Ogilvie, K. W.; Geiss, J.; Bochsler, P.

    1983-01-01

    The ion composition instrument (ICI) on ISEE-3 observed the isotopes of helium of mass 3 and 4 in the solar wind almost continuously between August 1978 and July 1982. This period included the increase towards the maximum of solar activity cycle 21, the maximum period, and the beginning of the descent towards solar minimum. Observations were made when the solar wind speed was between 300 and 620 km/s. For part of the period evidence for regular interplanetary magnetic sector structure was clear and a number of 3He flares occurred during this time.

  7. Erosion of carbon/carbon by solar wind charged particle radiation during a solar probe mission

    NASA Technical Reports Server (NTRS)

    Sokolowski, Witold; O'Donnell, Tim; Millard, Jerry

    1991-01-01

    The possible erosion of a carbon/carbon thermal shield by solar wind-charged particle radiation is reviewed. The present knowledge of erosion data for carbon and/or graphite is surveyed, and an explanation of erosion mechanisms under different charged particle environments is discussed. The highest erosion is expected at four solar radii. Erosion rates are analytically estimated under several conservative assumptions for a normal quiet and worst case solar wind storm conditions. Mass loss analyses and comparison studies surprisingly indicate that the predicted erosion rate by solar wind could be greater than by nominal free sublimation during solar wind storm conditions at four solar radii. The predicted overall mass loss of a carbon/carbon shield material during the critical four solar radii flyby can still meet the mass loss mission requirement of less than 0.0025 g/sec.

  8. The Solar Wind Energy Input Rate and Recovery of the Magnetospheric Ring Current during the Last Two Solar Cycles

    Microsoft Academic Search

    L. Biktash

    2008-01-01

    This study presents the recent results of our calculations of the solar wind energy input rate to the magnetospheric ring current in the main phase of magnetic storms used for simulation of Dst index based on solar wind data. For this purpose we studied the solar wind parameters during the last two solar cycles. We looked for geomagnetic storms and

  9. 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. [Los Alamos National Lab., NM (United States); Goldstein, B.E. [California Inst. of Technology, Pasadena, CA (United States). Jet Propulsion Lab.

    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.

  10. 78 FR 76609 - Genesis Solar, LLC; NRG Delta LLC; Mountain View Solar, LLC; Pheasant Run Wind, LLC; Pheasant Run...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-18

    ...EG13-64-000; FC13-13-000] Genesis Solar, LLC; NRG Delta LLC; Mountain View Solar, LLC; Pheasant Run Wind, LLC; Pheasant...Tuscola Wind II, LLC; Mountain Wind Power, LLC; Mountain Wind Power II, LLC; Summerhaven Wind, LP;...

  11. A view of solar magnetic fields, the solar corona, and the solar wind in three dimensions

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.; Wilcox, J. M.

    1978-01-01

    In the last few years it has been recognized that the solar corona and the solar wind are three-dimensional. The deviations from spherical or even cylindrical symmetry are first-order effects, which are important for a basic description and physical understanding of the coronal expansion. Models of coronal magnetic fields are considered along with the characteristics of large-scale solar structure, the interplanetary magnetic field, coronal holes, geomagnetic activity, cosmic rays, and polar fields of the sun. It is pointed out that the present understanding of coronal and interplanetary morphology is based on data acquired during the descending part and the minimum of the considered sunspot cycle.

  12. Velocity variations in the high-latitude solar wind

    SciTech Connect

    Neugebauer, M.; Goldstein, B.E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); McComas, D.J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Suess, S.T. [Marshall Space Flight Center, Huntsville, Alabama 35812 (United States); Balogh, A. [Imperial College, London (United Kingdom)

    1996-07-01

    Velocity variations of the solar wind from a south polar coronal hole registered by the Ulysses spacecraft in 1994 are analyzed. Power spectra of hourly averages in the Hz range are presented. {copyright} {ital 1997 American Institute of Physics.}

  13. 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.

  14. 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.

  15. Ion Beam Instabilities in Solar Wind Reconnection Exhaust

    NASA Astrophysics Data System (ADS)

    Kristensen, H.; Stevens, M. L.; Verscharen, D.; Kasper, J. C.

    2013-12-01

    Observations of the solar wind proton velocity distribution using the Wind faraday cups were studied during inside of and near previously published magnetic reconnection exhausts. We have attempted to test the hypothesis that interpenetrating ion beams in the solar wind can be driven by the reconnection process. The beam and core within the solar wind were fit as two bi-Maxwellian distributions and their velocities compared to Alfvén wave velocity and inflow speed. The differential flow between the beam and the core was found to be mostly in the range of Alfvénic to super Alfvénic instead of reflecting the inflow speed. Further analysis revealed that these beam configurations are frequently unstable and excite parallel-propagating plasma modes. This research was supported by the NSF grant for the Solar Physics REU Program at the Smithsonian Astrophysical Observatory (AGS-1263241).

  16. 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.

  17. Analysis of ISEE-3/ICE solar wind data. Final report

    SciTech Connect

    Coplan, M.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.

  18. 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.

  19. The Solar Wind Around Pluto (SWAP) Instrument Aboard New Horizons

    Microsoft Academic Search

    D. McComas; F. Allegrini; F. Bagenal; P. Casey; P. Delamere; D. Demkee; G. Dunn; H. Elliott; J. Hanley; K. Johnson; J. Langle; G. Miller; S. Pope; M. Reno; B. Rodriguez; N. Schwadron; P. Valek; S. Weidner

    2008-01-01

    The Solar Wind Around Pluto (SWAP) instrument on New Horizons will measure the interaction between the solar wind and ions created by atmospheric loss from Pluto. These measurements provide\\u000a a characterization of the total loss rate and allow us to examine the complex plasma interactions at Pluto for the first time.\\u000a Constrained to fit within minimal resources, SWAP is optimized

  20. The Solar Wind Around Pluto (SWAP) Instrument Aboard New Horizons

    Microsoft Academic Search

    D. McComas; F. Allegrini; F. Bagenal; P. Casey; P. Delamere; D. Demkee; G. Dunn; H. Elliott; J. Hanley; K. Johnson; J. Langle; G. Miller; S. Pope; M. Reno; B. Rodriguez; N. Schwadron; P. Valek; S. Weidner

    The Solar Wind Around Pluto (SWAP) instrument on New Horizons will measure the interaction between the solar wind and ions created by atmospheric loss from Pluto. These measurements provide\\u000a a characterization of the total loss rate and allow us to examine the complex plasma interactions at Pluto for the first time.\\u000a Constrained to fit within minimal resources, SWAP is optimized

  1. Systematic averaging interval effects on solar wind statistics

    NASA Astrophysics Data System (ADS)

    Isaacs, J. J.; Tessein, J. A.; Matthaeus, W. H.

    2015-02-01

    The choice of interval of averaging in computing statistics of solar wind fluctuations is known to be a sensitive issue in which the need for adequate sampling statistics must be balanced with the complications of establishing an ensemble, given that the solar wind admits inhomogeneity, structure, and variability at its sources. Here we examine the quantitative dependence of interval of averaging (sample size) on estimates of basic statistics such as means, variances, and anisotropies of the measured interplanetary magnetic field.

  2. Dust acoustic instability driven by solar and stellar winds

    SciTech Connect

    Vranjes, J. [Belgian Institute for Space Aeronomy, Ringlaan 3, 1180 Brussels (Belgium)

    2011-11-29

    A quantitative analysis is presented of the dust acoustic wave instability driven by the solar or stelar wind. This is a current-less kinetic instability which develops in permeating plasmas, i.e.., when one quasi-neutral electron-ion plasma propagates through another quasi-neutral plasma which contains dust, electrons and ions. The cometary dusty plasma in the solar wind appears to be practically always unstable.

  3. 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.

  4. Heating of the interstellar medium by the solar wind

    NASA Technical Reports Server (NTRS)

    Kunc, J. A.; Wu, F. M.; Judge, D. L.

    1983-01-01

    The heating of inflowing interstellar gas by the solar wind is calculated. The experimental differential cross sections have been used for calculating electron-H(He) and proton-H(He) elastic scattering rate coefficients. The solar wind is assumed to be a two-component (protons and electrons), steady, spherically symmetric stream moving radially outward, with the inflowing gas following Keplerian trajectories. The spatial distributions of effective temperature increase within interplanetary space have been obtained.

  5. Weakly inhomogeneous MHD turbulence and transport of solar wind fluctuations

    NASA Technical Reports Server (NTRS)

    Matthaeus, W. H.; Zhou, Y.; Oughton, S.; Zank, G. P.

    1992-01-01

    An evaluation is conducted of recent theories of small-scale MHD turbulence transport in an inhomogeneous background that are pertinent to the evolution of solar wind turbulence. Attention is given to the WKB formalism that has been used in many solar wind-related physics applications, with a view to its shortcomings. Also discussed are the structure of two-scale transport theories, and their relationship to WKB theory in light of multiple-scales analysis.

  6. 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.

  7. The Dynamic Character of the Polar Solar Wind

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    The Solar and Heliospheric Observatory (SOHO) Large Angle and Spectrometric Coronagraph C2 and Solar Terrestrial Relations Observatory (STEREO) COR2A coronagraph images, when analyzed using correlation tracking techniques, show a surprising result in places ordinarily thought of as "quiet" solar wind above the poles in coronal hole regions. Instead of the static well-ordered flow and gradual acceleration normally expected, coronagraph images show outflow in polar coronal holes consisting of a mixture of intermittent slow and fast patches of material. We compare measurements of this highly variable solar wind from C2 and COR2A images and show that both coronagraphs measure essentially the same structures. Measurements of the mean velocity as a function of height of these structures are compared with mass flux determinations of the solar wind outflow in the large polar coronal hole regions and give similar results.

  8. 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.

  9. 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.

  10. Correlated variations in the solar neutrino flux and the solar wind and the relation to the solar neutrino problem

    SciTech Connect

    McNutt, R.L. Jr. [Johns Hopkins Univ., Laurel, MD (United States)

    1995-12-08

    Solar wind parameters from the Massachusetts Institute of Technology (MIT) plasma experiment on the IMP 8 spacecraft overlap {approximately}19 years of published neutrino flux observations from the Homestake experiment. A strong correlation is found between neutrino flux and solar wind properties, in particular, the solar wind mass flux. The correlation is significantly better than any anticorrelation with sunspot number and is comparable to those previously found with photospheric magnetic flux and shifts in p-mode frequencies. If current notions of solar structure are correct, these observations require new fundamental physics of neutrinos. For a proper choice of neutrino parameters, the level of variations is consistent with resonant conversion of electron neutrinos to a nondetected flavor eigenstate mediated by the magnetic field in the sun`s convective zone. The solar wind mass flux may act as a proxy for this field, producing the solar wind-neutrino flux connection. 36 refs., 5 figs., 2 tabs.

  11. Solar wind precipitation - a comparison between Mars and Venus

    NASA Astrophysics Data System (ADS)

    Stenberg Wieser, Gabriella; Nilsson, Hans; Futaana, Yoshifumi; Holmström, Mats; Barabash, Stas

    2015-04-01

    Mars and Venus both have atmospheres but both lack a substantial intrinsic magnetic field. Hence, their interaction with the solar wind is similar. Due to currents set up in the ionospheres the interplanetary magnetic field embedded in the solar wind drapes around the planets forming induced magnetospheres. The plasma instrument packages ASPERA-3 and ASPERA-4 on the two spacecraft Mars Express and Venus Express are very similar and invite to a comparison between the two plasma environments. In this study we used the Ion Mass Analyser (IMA) on both spacecraft to investigate the solar wind precipitation onto the upper atmospheres. We focus on the differences between the two planets. We conclude that on Mars we regularly observe precipitating solar wind ions (H+ and He2+) inside the induced magnetosphere boundary (IMB). The precipitation is clearly guided by the solar wind convection electric field and He2+ and H+ are seen independently of each other. On Venus precipitation of He2+ is only observed close to the IMB and always together with H+. The precipitation events on Venus have no clear correlation with the solar wind electric field.

  12. 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.

  13. Solar wind speed and coronal flux-tube expansion

    Microsoft Academic Search

    Y.-M. Wang

    1990-01-01

    The hypothesis that the solar wind speed at 1 AU and the rate of magnetic flux-tube expansion in the corona are inversely correlated is shown to be consistent with observations extending over the last 22 years. This empirical relationship allows the daily wind speeds at earth to be predicted from a current-free extrapolation of the observed photospheric field into the

  14. Solar wind energy dissipation in the upper atmosphere

    Microsoft Academic Search

    G. W. Proelss

    1983-01-01

    Heating and momentum transfer deriving from solar wind energy generate a permanent disturbance zone in the polar region, which is characterized by increased temperature and pressure, strong vertical and horizontal winds, and significant changes in the density structure. Heavier gases, such as Ar, O2, and N2, are enhanced, whereas He is depleted and O is moderately enhanced or depleted, depending

  15. Ionosphere response to solar wind high-speed streams

    Microsoft Academic Search

    Jiuhou Lei; Jeffrey P. Thayer; Jeffrey M. Forbes; Qian Wu; Chengli She; Weixing Wan; Wenbin Wang

    2008-01-01

    We present 9- and 7-day periodic oscillations in the global mean Total Electron Content (TEC) from 1 January 2005 to 31 December 2006. Spectral analysis indicates that the pronounced periodicities of 9 and 7 days observed in TEC are associated with variations in solar wind high-speed streams and geomagnetic activity. Neutral temperature and winds near 250 km, measured by a

  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. 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.

  18. 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.

  19. Laboratory Investigations of Solar Wind Sputtering

    NASA Astrophysics Data System (ADS)

    McLain, J. L.; Keller, J. W.; Farrell, W. M.

    2012-12-01

    Ion scattering spectrometric measurements will be presented on energetic neutral atoms (ENAs) reflecting from lunar regolith simulates. Mass selected H+ and He2+ pulsed ion beams were used to simulate the solar wind impacting a solid target. A low energy ion, 0.5 to 5 keV, impacting a surface loses energy by ionization, secondary electron emission, excitation, and potential sputtering. When the straggling of low energy ions impacting a surface becomes comparable to the penetration depth, backscattering of ions and ENAs can occur. This backscattering varies as a function of the incident ion angle. An increase in the neutral sputtering yield can occur at angles >60° due to the forward direction of the secondary cascade. Therefore, surface roughness plays a major role in the backscattering angle and energy distribution. The regolith of airless bodies is very rough on the microscopic scale which can lead to transmission of the incident ion through the grains and possible adsorption of the ejecta onto neighboring surfaces. These effects as well as target temperature, porosity, grain size and hydrogen implantation will be discussed.

  20. 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.

  1. 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.

  2. Solar Wind ~20-300 keV Superhalo Electrons

    NASA Astrophysics Data System (ADS)

    Wang, L.; Yang, L.; He, J.; Tu, C. Y.; Pei, Z.

    2014-12-01

    High-energy superhalo electrons are present in the interplanetary medium even in absence of any solar activity, carrying important information on the electron acceleration in the solar wind. We present a statistical survey of ~20-300 keV superhalo electrons measured at 1 AU by the WIND 3DP instrument during quiet-time periods from 1995 January through 2013 December. The velocity distribution function of the observed quiet-time superhalo electrons generally fits to a power-law spectrum, f ~ v-?, with ? ranging from ~4 to ~10. The integrated density of these superhalo electrons at 20-300 keV, nsup, ranges from 10?9 cm?3 to 10?5 cm?3. Both log(nsup) and ? show a good correlation with the sunspot number, with larger density and softer spectrum (?~ 6-8) at solar maximum, and smaller density and harder spectrum (?~ 4-5) at solar minimum. The observed power-law spectrum also has no clear association with flares, CMEs, active regions and solar wind core populations, while it shows a weak (~0.3) correlation with in situ solar wind turbulence spectrum. These results suggest that the seed particles of quiet-time superhalo electrons could originate from the Sun, and their acceleration could mainly occur in the interplanetary medium, probably by the electron interaction with solar wind turbulence, or by acceleration at the CIRs.

  3. 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 interaction physics are required not only for further development of ENA imaging of airless bodies but also for understanding space weathering, ion implantation processes, and impact of backscattering on the global solar wind - Moon interaction picture.

  4. Application of AN Empirically-Derived Polytropic Index for the Solar Wind to a Solar Wind Shock Propagation Model

    Microsoft Academic Search

    Tracy Lynn Totten

    1994-01-01

    Data from the Helios 1 spacecraft have been used to determine an empirical value for the polytropic index for the free-streaming solar wind. Application of this non-adiabatic polytropic index to a two-dimensional solar wind computer model to simulate the effects of thermal heat conduction has been investigated. The current project involves the insertion of this empirically-derived polytropic index into a

  5. Solar cycle variations of solar wind dynamics and structures

    Microsoft Academic Search

    J. D. Richardson; J. C. Kasper

    2008-01-01

    This paper reviews solar cycle variations in the heliosphere. We show that some solar cycle changes, such as the correlation between speed and density, result from the evolution of the solar structure from dipolar with strong latitudinal gradients at solar minimum to a disordered field with little latitudinal variation at solar maximum. Other changes, such as the variation of the

  6. Magnetic collimation of the solar and stellar winds

    E-print Network

    K. Tsinganos; S. Bogovalov

    2000-06-01

    We resolve the paradox that although magnetic collimation of an isotropic solar wind results in an enhancement of its proton flux along the polar directions, several observations indicate a wind proton flux peaked at the equator. To that goal, we solve the full set of the time-dependent MHD equations describing the axisymmetric outflow of plasma from the magnetized and rotating Sun, either in its present form of the solar wind, or, in its earlier form of a protosolar wind. Special attention is directed towards the collimation properties of the solar outflow at large heliocentric distances. For the present day solar wind it is found that the poloidal streamlines and fieldlines are only slightly focused toward the solar poles. However, even such a modest compression of the flow by the azimuthal magnetic field would lead to an increase of the mass flux at the polar axis by about 20% at 1 AU, relatively to its value at the equator, for an initially isotropic at the base wind, contrary to older and recent (Prognoz, Ulysses, SOHO) observations. For the anisotropic in heliolatitude wind with parameters at the base inferred from in situ observations by ULYSSES/SWOOPS and SOHO/CDS the effect of collimation is almost totally compensated by the initial velocity and density anisotropy of the wind. This effect should be taken into account in the interpretation of the recent SOHO observations by the SWAN instrument. Similar simulations have been performed for a five- and ten-fold increase of the solar angular velocity corresponding presumably to the wind of an earlier phase of our Sun. For such conditions it is found that for initially radial streamlines, the azimuthal magnetic field created by the fast rotation focus them toward the rotation axis and forms a tightly collimated jet.

  7. Improving Data Drivers for Coronal and Solar Wind Models

    Microsoft Academic Search

    C. N. Arge; C. J. Henney; J. Koller; W. A. Toussaint; J. W. Harvey; S. Young

    2011-01-01

    Global estimates of the solar photospheric magnetic field distribution are critical for space weather forecasting. These global maps are the essential data input for accurate modeling of the corona and solar wind, which is vital for gaining the basic understanding necessary to improve space weather forecasting models. We are now testing the global photospheric field maps generated by the Air

  8. Solar wind flow past nonmagnetic planets-Venus and Mars

    Microsoft Academic Search

    John R. Spreiter; Audrey L. Summers; Arthur W. Rizzi

    1970-01-01

    The hydromagnetic theory of solar wind flow past the Earth has been extended and modified so as to be applicable to nonmagnetic planets, such as Venus and Mars, that have a sufficient ionosphere to deflect the solar plasma around the planet and its atmosphere. The principal difference in the analysis stems from the fact that the current sheath that bounds

  9. Velocity Distributions and Proton Beam Production in the Solar Wind

    SciTech Connect

    Pierrard, Viviane; Voitenko, Yuriy [Belgian Institute for Space Aeronomy, Ringlaan-3-Avenue Circulaire, B-1180 Brussels (Belgium)

    2010-03-25

    Helios, Ulysses, and Wind spacecraft have observed the velocity distribution functions (VDFs) of solar wind particles deviating significantly from Maxwellians. We review recent models using different approximations and mechanisms that determine various observed characteristics of the VDFs for the electrons, protons and minor ions. A new generation mechanism is proposed for super-Alfvenic proton beams and tails that are often observed in the fast solar wind. The mechanism is based on the proton trapping and acceleration by kinetic Alfven waves (KAWs), which carry a field-aligned potential well propagating with super-Alfven velocities.

  10. Validation of a synoptic solar wind model

    Microsoft Academic Search

    O. Cohen; I. V. Sokolov; I. I. Roussev; T. I. Gombosi

    2008-01-01

    We present a validation of a three-dimensional magnetohydrodynamic model for the solar corona and the inner heliosphere. We compare the results of the model with long-term satellite data at 1 AU for a 1 year period during solar minimum and another year period of solar maximum. Overall, the model predicts rather well the magnitude of the magnetohydrodynamical variables for solar

  11. Solar coronal plumes and the fast solar wind

    E-print Network

    Dwivedi, B N

    2015-01-01

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

  12. Wind/SWE observations of firehose constraint on solar wind proton temperature anisotropy

    E-print Network

    Richardson, John

    temperature anisotropies observed by the two Faraday Cup (FC) instru- ments of the Solar Wind Experiment (SWE and our observations. [5] A Faraday Cup is an energy/charge instrument with a large, conical field of view

  13. Small Scale Magnetic Reconnection in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Foster, Alice; Owen, Christopher; Forsyth, Colin; Rae, Jonathan; Fazakerley, Andrew; Carr, Christopher; Dandouras, Iannis

    2015-04-01

    Previous studies of magnetic reconnection in the solar wind have suggested that a single reconnection X-line can extend and be active over millions of kilometres. We present a case study of an event observed in the solar wind on the 2nd March 2006 by the four Cluster spacecraft. We utilised the four point measurement capability to study the event at sub-second resolution over separation distances of 10,000 km as well as over the larger scales separating Cluster from ACE and WIND. We thus test the consistency of the temporal and spatial structure of magnetic reconnection from large scales to small scales. This reconnection event showed significant differences between the Cluster spacecraft, particularly in the magnetic field data, suggesting reconnection in the solar wind can be variable over relatively small temporal and or spatial scales (< 60 s and/or ~ 10,000 km). This leads to the conclusion that magnetic reconnection in the solar wind is not necessarily large scale and may be patchy in nature. This result raises questions about our current understanding of magnetic reconnection in the solar wind.

  14. Acceleration of weakly collisional solar-type winds

    E-print Network

    I. Zouganelis; N. Meyer-Vernet; S. Landi; M. Maksimovic; F. Pantellini

    2005-05-16

    One of the basic properties of the solar wind, that is the high speed of the fast wind, is still not satisfactorily explained. This is mainly due to the theoretical difficulty of treating weakly collisional plasmas. The fluid approach implies that the medium is collision dominated and that the particle velocity distributions are close to Maxwellians. However the electron velocity distributions observed in the solar wind depart significantly from Maxwellians. Recent kinetic collisionless models (called exospheric) using velocity distributions with a suprathermal tail have been able to reproduce the high speeds of the fast solar wind. In this letter we present new developments of these models by generalizing them over a large range of corona conditions. We also present new results obtained by numerical simulations that include collisions. Both approaches calculate the heat flux self-consistently without any assumption on the energy transport. We show that both approaches - the exospheric and the collisional one - yield a similar variation of the wind speed with the basic parameters of the problem; both produce a fast wind speed if the coronal electron distribution has a suprathermal tail. This suggests that exospheric models contain the necessary ingredients for the powering of a transonic stellar wind, including the fast solar one.

  15. Improving solar wind modeling at Mercury: Incorporating transient solar phenomena into the WSA-ENLIL model

    NASA Astrophysics Data System (ADS)

    Dewey, R. M.; Baker, D. N.; Anderson, B. J.; Benna, M.; Johnson, C. L.; Korth, H.; Gershman, D. J.; Ho, G. C.; McClintock, W. E.; Odstrcil, D.; Philpott, L. C.; Raines, J. M.; Schriver, D.; Slavin, J. A.; Solomon, S. C.; Winslow, R. M.; Zurbuchen, T.

    2014-12-01

    Coronal mass ejections (CMEs) and other transient solar phenomena play important roles in magnetospheric and exospheric dynamics. Although a planet may only occasionally interact with the products of these events, such transient phenomena can result in departures from the background solar wind that often involve more than an order of magnitude greater ram pressure and interplanetary electric field applied to the magnetosphere. For Mercury, an order of magnitude greater ram pressure can push the magnetopause to the planet's surface, exposing the surface directly to the solar wind. In order to understand how the solar wind interacts with Mercury's magnetosphere and exosphere, previous studies have used the Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool to calculate basic and composite solar wind parameters, such as solar wind velocity (V) and Alfvén Mach number (MA) at Mercury's orbital location. This model forecasts only the background solar wind, however, and does not include these transient events. The Cone extension permits the inclusion of CMEs and other phenomena, and thus enables characterization of the effect of strong solar wind perturbations on the Mercury system. The Cone extension is predicated on the assumption of constant angular and radial velocities of ejecta to integrate them into the WSA-ENLIL coupled model. Comparisons of the model results with the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft observations indicate that the WSA-ENLIL-Cone model more accurately forecasts total solar wind conditions at Mercury and has greater predictive power for magnetospheric and exospheric processes than the WSA-ENLIL model alone.

  16. Imprint of the Sun on the Solar Wind

    Microsoft Academic Search

    Richard Woo; Shadia Rifai Habbal

    1999-01-01

    Observations of the inner corona in polarized brightness by the Mauna Loa Mk III K-coronameter at 1.15 R_solar and soft X-rays by Yohkoh at 1.03 R_solar are combined with 1995 Ulysses radio occultation measurements of the solar wind to demonstrate that the signatures of the coronal hole boundary, active regions, and bright points are present in the heliocentric distance range

  17. Self-consistent Castaing distribution of solar wind turbulent fluctuations

    E-print Network

    Sorriso-Valvo, L; Lijoi, L; Perri, S; Carbone, V

    2015-01-01

    The intermittent behavior of solar wind turbulent fluctuations has often been investigated through the modeling of their probability distribution functions (PDFs). Among others, the Castaing model (Castaing et al. 1990) has successfully been used in the past. In this paper, the energy dissipation field of solar wind turbulence has been studied for fast, slow and polar wind samples recorded by Helios 2 and Ulysses spacecraft. The statistical description of the dissipation rate has then be used to remove intermittency through conditioning of the PDFs. Based on such observation, a self-consistent, parameter-free Castaing model is presented. The self-consistent model is tested against experimental PDFs, showing good agreement and supporting the picture of a multifractal energy cascade at the origin of solar wind intermittency.

  18. The Yaglom law in the expanding solar wind

    SciTech Connect

    Gogoberidze, G.; Perri, S.; Carbone, V., E-mail: g.gogoberidze@warwick.ac.uk [Dipartimento di Fisica, Università della Calabria, I-87036 Rende (Italy)

    2013-06-01

    We study the Yaglom law, which relates the mixed third-order structure function to the average dissipation rate of turbulence, in a uniformly expanding solar wind by using the two-scale expansion model of magnetohydrodynamic (MHD) turbulence. We show that due to the expansion of the solar wind, two new terms appear in the Yaglom law. The first term is related to the decay of the turbulent energy by nonlinear interactions, whereas the second term is related to the non-zero cross-correlation of the Elsässer fields. Using magnetic field and plasma data from WIND and Helios 2 spacecrafts, we show that at lower frequencies in the inertial range of MHD turbulence the new terms become comparable to Yaglom's third-order mixed moment, and therefore they cannot be neglected in the evaluation of the energy cascade rate in the solar wind.

  19. The interaction of active comets with the solar wind

    NASA Technical Reports Server (NTRS)

    Neugebauer, Marcia

    1990-01-01

    The interaction of the solar wind with active comets is investigated based on observations of cometary plasma processes and studies of comets using telescopes and photographic plates. Data were also collected when a spacecraft flew through the tail of Comet Giacobini-Zinner in 1985 and five spacecraft encountered Comet Halley in 1986. The solar wind is considered to be supersonic (thermal Mach number 2-10) and to carry a magnetic field twisted into an Archimedean spiral by the rotation of the sun. Since the wind can change its properties during the time a spacecraft is inside the ionosphere or magnetosphere of the body being studied, it is difficult to separate spatial from temporal effects. Photoionization results in addition of plasma to the solar wind. Between the outer and inner edges of the cometosheath, the increasing rate of ion pickup causes the flow to slow down until it stagnates, while the plasma density and the magnetic field strength increase.

  20. Self-consistent Castaing Distribution of Solar Wind Turbulent Fluctuations

    NASA Astrophysics Data System (ADS)

    Sorriso-Valvo, L.; Marino, R.; Lijoi, L.; Perri, S.; Carbone, V.

    2015-07-01

    The intermittent behavior of solar wind turbulent fluctuations has often been investigated through the modeling of their probability distribution functions (PDFs). Among others, the Castaing model has successfully been used in the past. In this paper, the energy dissipation field of solar wind turbulence has been studied for fast, slow, and polar wind samples recorded by Helios 2 and Ulysses spacecraft. The statistical description of the dissipation rate has then been used to remove intermittency through conditioning of the PDFs. Based on such observation, a self-consistent, parameter-free Castaing model is presented. The self-consistent model is tested against experimental PDFs, showing good agreement and supporting the picture of a multifractal energy cascade at the origin of solar wind intermittency.

  1. 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. PMID:22304144

  2. Ulysses solar wind plasma observations at high latitudes

    SciTech Connect

    Riley, P.; Bame, S.J.; Barraclough, B.L. [and others

    1996-10-01

    Ulysses reached its peak northerly heliolatitude of 80.2{degrees}N on July 31, 1995, and now is moving towards aphelion at 5.41 AU which it will reach in May, 1998. We summarize measurements from the solar wind plasma experiment, SWOOPS, emphasizing northern hemispheric observations but also providing southern and equatorial results for comparison. The solar wind momentum flux during Ulysses` fast pole-to- pole transit at solar minimum was significantly higher over the poles than at near-equatorial latitudes, suggesting a non-circular cross section for the heliosphere. Furthermore, modest asymmetries in the wind speed, density, and mass flux were observed between the two hemispheres during the fast latitude scan. The solar wind was faster and less dense in the north than in the south. These asymmetries persist in the most recent high- and mid-latitude data but are less pronounced. As of July 1, 1996 the northern fast solar wind has lacked any strong stream interactions or shocks and, although a comprehensive search has not yet been made, no CMEs have yet been identified during this interval. On the other hand, Alfv{acute e}nic, compressional, and pressure balanced features are abundant at high latitudes. The most recent data, at 4 AU and 32{degrees}N, has begun to show the effects of solar rotation modulated features in the form of recurrent compressed regions.

  3. Relationship Between Solar Wind Speed and Coronal Magnetic Field Properties

    E-print Network

    Fujiki, Ken'ichi; Iju, Tomoya; Hakamada, Kazuyuki; Kojima, Masayoshi

    2015-01-01

    We have studied the relationship between the solar-wind speed $[V]$ and the coronal magnetic-field properties (a flux expansion factor [$f$] and photospheric magnetic-field strength [$B_{\\mathrm{S}}$]) at all latitudes using data of interplanetary scintillation and solar magnetic field obtained for 24 years from 1986 to 2009. Using a cross-correlation analyses, we verified that $V$ is inversely proportional to $f$ and found that $V$ tends to increase with $B_{\\mathrm{S}}$ if $f$ is the same. As a consequence, we find that $V$ has extremely good linear correlation with $B_{\\mathrm{S}}/f$. However, this linear relation of $V$ and $B_{\\mathrm{S}}/f$ cannot be used for predicting the solar-wind velocity without information on the solar-wind mass flux. We discuss why the inverse relation between $V$ and $f$ has been successfully used for solar-wind velocity prediction, even though it does not explicitly include the mass flux and magnetic-field strength, which are important physical parameters for solar-wind accele...

  4. Solar Mass Ejection Imager (SMEI) Solar Wind 3-D Analysis of the January 20, 2005 CME

    Microsoft Academic Search

    B. V. Jackson; A. Buffington; P. P. Hick; Y. Yu; D. Webb

    2005-01-01

    The Solar Mass Ejection Imager (SMEI) has observed the inner heliospheric response in white light from over 200 CMEs. One of these, on January 20, 2005, produced one of the largest Solar Energetic Particle events ever recorded. We show SMEI orbital difference images and the 3D solar wind reconstruction of this well-observed CME, and demonstrate how we can track its

  5. A Solar Activity Dependence of A Solar Wind Effect on Cosmic Ray Intensity Variations

    Microsoft Academic Search

    H. Kojima; Y. Hayashi; K. Hayashi

    2008-01-01

    We have investigated a solar activity dependence of a solar wind (SW) effect on cosmic ray intensity (CRI) variations. The SW effect discussed here is not concerned with transient origins such as Forbush decreases nor with known solar modulations. The effect is represented by the regression coefficient of CRI variations with SW velocities. CRI data we used have been recorded

  6. VLBI-experiments on research of solar wind plasma

    E-print Network

    M. B. Nechaeva; V. G. Gavrilenko; Y. N. Gorshenkov; . B. N. Lipatov; L. Xiang; I. E. Molotov; A. B. Pushkarev; R. Shanks; G. Tuccari

    2004-12-30

    This work devotes to investigations of solar corona and solar wind plasma by the method of radio probing with using of very long baseline interferometry (VLBI). We performed the theoretical calculation of power spectrum of interferometric response to radio source emission, passed through the turbulent medium. Data of theoretical analysis are compared with results of international VLBI experiments on investigations of solar wind plasma. The observations were realized in 1998, 1999, 2000 with participation of radio telescopes, included at Low Frequency VLBI Network (LFVN): Bear Lakes (RT-64, Russia), Puschino (RT-22, Russia), Urumqi (RT-25, China), Noto (RT-32, Italy), Shanghai (RT-25, China) and others. Preprocessing was carried out with using of S2 correlator at Penticton (Canada). Post processing of experimental data was performed at RRI (Russia) and was aimed to obtain value of solar wind velocity and index of spatial spectrum of electron density fluctuations.

  7. Sharp boundaries of small-and middle-scale solar wind structures

    E-print Network

    Richardson, John

    Sharp boundaries of small- and middle-scale solar wind structures M. O. Riazantseva1 and G. N-scale solar wind plasma structures. We present examples and statistical results from simultaneous plasma and magnetic field measurements by Interball-1 and Wind from 1996 to 1999. The behavior of the solar wind bulk

  8. Path of the solar wind energy into the Earth s magnetosphere

    Microsoft Academic Search

    I. Alexeev

    2002-01-01

    The solar wind MHD generator is an unique energy source for all magnetospheric processes. The field-aligned currents directly transport the energy and momentum of the solar wind plasma to the Earth's ionosphere. The magnetospheric lobe and plasma sheet convection generated by the solar wind is another magnetospheric energy source. Plasma sheet particles and cold ionospheric polar wind ions are accelerated

  9. An integrated energy storage scheme for a dispatchable solar and wind powered energy system

    Microsoft Academic Search

    Jared B. Garrison; Michael E. Webber

    2011-01-01

    This research analyzed an integrated energy system that includes a novel configuration of wind and solar coupled with two storage methods to make both wind and solar sources dispatchable during peak demand, thereby enabling their broader use. Named DSWiSS for Dispatchable Solar and Wind Storage System, the proposed system utilizes compressed air energy storage (CAES) that is driven from wind

  10. Magnetospheric Resonances Driven by Solar Wind Dynamic Pressure Fluctuations

    NASA Astrophysics Data System (ADS)

    Claudepierre, S. G.; Hudson, M. K.; Lotko, W.; Lyon, J.; Denton, R. E.

    2009-12-01

    More than 50 years ago, Dungy suggested that the Earth’s magnetosphere could support magnetohydrodynamic (MHD) resonances. Extensive observational and theoretical work has established the existence of resonant standing waves on closed geomagnetic field lines. These oscillations, known as field line resonances (FLR’s), are observed across most of the dayside magnetosphere and occupy the lowest frequency range of the ultra-low frequency (ULF) spectrum ( ? 100 mHz). The spatial distribution and polarization characteristics of toroidal mode FLR’s suggest that the solar wind is the ultimate source of the compressional energy that excites these resonances. However, it remains unclear which solar wind parameter(s) is responsible, with observational evidence supporting a Kelvin-Helmholtz mechanism and/or periodic fluctuations in the solar wind dynamic pressure. To investigate these issues, we present results from Lyon-Fedder-Mobarry (LFM) global MHD simulations of the solar wind-magnetosphere interaction. The simulations are driven by synthetic solar wind conditions, where idealized ULF oscillations are embedded in the upstream solar wind. The simulation results suggest that ULF oscillations in the solar wind dynamic pressure can drive toroidal mode FLR’s across most of the dayside magnetosphere. In addition, the simulation results suggest that these same upstream fluctuations can energize magnetospheric cavity mode oscillations. We find that the cavity mode oscillation and the FLR are coupled, which leads to an enhancement of the FLR’s at the cavity mode eigenfrequencies. Furthermore, we find no evidence that magnetopause Kelvin-Helmholtz (KH) waves, which are also present in our simulations, drive FLR’s. Finally, we show that the spatial and spectral characteristics of the dynamic pressure driven waves are more favorable for a radial diffusion-type interaction with radiation belt electrons, when compared with those of the KH waves.

  11. Results From The Genesis Autonomous Solar Wind Regime Algorithm

    NASA Astrophysics Data System (ADS)

    Steinberg, J. T.; Barraclough, B. L.; Dors, E. E.; Neugebauer, M.; Wiens, R. C.

    Launched on August 8, 2001, the NASA Genesis mission is now collecting samples of the solar wind in various materials, and will return those samples to Earth for analysis in 2004. A primary science goal of Genesis is the determination of the elemental and isotopic composition of the solar atmosphere from the solar wind material returned. Because the solar wind itself is known to exhibit compositional variations across dif- ferent types of solar wind flows, Genesis exposes different collectors to solar wind originating from three flow types: coronal hole (CH), coronal mass ejection (CME), and interstream (IS) flows. Flow types are identified using in situ measurements of so- lar wind ions and electrons from electrostatic analyzers carried by Genesis. The flow regime selection algorithm and subsequent collector deployment on Genesis act au- tonomously. The algorithm takes into account the proton speed, proton temperature, alpha particle abundance, and the presence of counter-streaming suprathermal elec- trons as determined onboard. Autonomous determination of counter-streaming elec- trons is novel, as is the simultaneous utilization of electron information and ion mo- ments in logic that autonomously controls the science payload. Results to date show that solar wind has recently been dominated by IS flow with frequent CMEs. Between 24 August 2001 and 31 December 2001, the Genesis algo- rithm categorized the flow to be 67 % IS, 26% CME, and 7% CH. Counter-streaming electrons signatures were identified for 23% of that total time interval. The Genesis onboard shock detector was set seventeen times, and nearly all were verified to be ac- tual CME-associated shocks. We will present the results of the autonomous algorithm obtained up to the time of the EGS meeting, as well as our assessment of the validity of those onboard results.

  12. SWICS/Ulysses and MASS/wind observations of solar wind sulfur charge states

    NASA Technical Reports Server (NTRS)

    Cohen, C. M. S.; Galvin, A. B.; Hamilton, D. C.; Gloeckler, G.; Geiss, J.; Bochsler, P.

    1995-01-01

    As Ulysses journeys from the southern to the northern solar pole, the newly launched Wind spacecraft is monitoring the solar wind near 1 AU, slightly upstream of the Earth. Different solar wind structures pass over both spacecraft as coronal holes and other features rotate in and out of view. Ulysses and Wind are presently on opposing sides of the sun allowing us to monitor these streams for extended periods of time. Composition measurements made by instruments on both spacecraft provide information concerning the evolution and properties of these structures. We have combined data from the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses and the high mass resolution spectrometer (MASS) on Wind to determine the charge state distribution of sulfur in the solar wind. Both instruments employ electrostatic deflection with time-of-flight measurement. The high mass resolution of the MASS instrument (M/Delta-M approximately 100) allows sulfur to be isolated easily while the stepping energy/charge selection provides charge state information. SWICS measurements allow the unique identification of heavy ions by their mass and mass/charge with resolutions of M/Delta-M approximately 3 and M/q/Delta(M/q) approximately 20. The two instruments complement each other nicely in that MASS has the greater mass resolution while SWICS has the better mass/charge resolution and better statistics.

  13. SWICS/Ulysses and MASS/wind observations of solar wind sulfur charge states

    NASA Astrophysics Data System (ADS)

    Cohen, C. M. S.; Galvin, A. B.; Hamilton, D. C.; Gloeckler, G.; Geiss, J.; Bochsler, P.

    1995-06-01

    As Ulysses journeys from the southern to the northern solar pole, the newly launched Wind spacecraft is monitoring the solar wind near 1 AU, slightly upstream of the Earth. Different solar wind structures pass over both spacecraft as coronal holes and other features rotate in and out of view. Ulysses and Wind are presently on opposing sides of the sun allowing us to monitor these streams for extended periods of time. Composition measurements made by instruments on both spacecraft provide information concerning the evolution and properties of these structures. We have combined data from the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses and the high mass resolution spectrometer (MASS) on Wind to determine the charge state distribution of sulfur in the solar wind. Both instruments employ electrostatic deflection with time-of-flight measurement. The high mass resolution of the MASS instrument (M/Delta-M approximately 100) allows sulfur to be isolated easily while the stepping energy/charge selection provides charge state information. SWICS measurements allow the unique identification of heavy ions by their mass and mass/charge with resolutions of M/Delta-M approximately 3 and M/q/Delta(M/q) approximately 20. The two instruments complement each other nicely in that MASS has the greater mass resolution while SWICS has the better mass/charge resolution and better statistics.

  14. Solar wind imaging facility (SWIFT) for space weather research

    NASA Astrophysics Data System (ADS)

    Kojima, Masayoshi; Tokumaru, Munetoshi; Fujiki, Ken-ichi; Ishida, Yoshio; Ohmi, Tomoaki; Hayashi, Keiji; Yamashita, Masahiro

    2003-02-01

    The interplanetary scintillation (IPS) method can observe the dynamics and structure of the solar wind in three dimensions with a relatively short time cadence (<1 day) using IPS radio sources distributed over the sky. Because of this advantage over in situ measurements, we have been conducting multi-station 327 MHz IPS observations at the Solar-Terrestrial Environment Laboratory. The IPS measurement is a line-of-sight integration which is a convolution of the solar wind structures, the distance of these from the Earth and other diffraction effects present along the line of sight. We have recently succeeded in developing a method to deconvolve the line-of-sight integration effects using a computer-assisted-tomography (CAT) technique to obtain solar wind speed and electron density fluctuations. The CAT analysis not only retrieves three-dimensional solar wind parameters, but also provides better spatial resolutions than previous analysis techniques. The present IPS system at STELab observes several tens of IPS sources a day. To make solar wind observations with higher spatial and temporal resolution using the CAT method, we need more perspective views of the solar wind. Therefore, we are planning a new UHF antenna with an effective collecting area of 5500m^2 that will observe more than 100 IPS sources per day. The antenna is designed with a tolerance for radio noise interference and high aperture efficiency. Based on the successful development of the IPS CAT analysis, we are presently continuing a US-Japan cooperative project for space weather research between UCSD/CASS and STELab. This project with the new antenna will enhance IPS/US cooperation including future comparative analyses of data from the Solar Mass Ejection Imager (SMEI) and from STEREO.

  15. Solar Wind Forecasting with the SOLIS-VSM

    NASA Astrophysics Data System (ADS)

    Robbins, S. J.; Henney, C. J.; Harvey, J. W.

    2005-05-01

    A web based solar wind forecasting resource applying a simple empirical model with SOLIS-VSM (Vector Spectromagnetograph) data is presented here. The solar wind empirical model uses the locations of coronal holes on the observed solar disk to forecast an estimated solar wind velocity at Earth. The model coefficients are estimated minimizing the difference between 10+ years of coronal hole images and the corresponding measured solar wind velocities. The coronal hole training data set was derived from Kitt Peak Vacuum Telescope (KPVT) He I 1083 nm images and photospheric magnetograms. The model can forecast up to 8.5 days in advance. The VSM estimated coronal hole images are derived from daily full-disk photospheric magnetograms and He I 1083 nm spectroheliograms using an automated coronal hole detection algorithm. Daily solar wind forecasts are planned to be automated using SOLIS-VSM data and made available publicly during the year 2005. The coronal hole data used here was compiled by K. Harvey and F. Recely using National Solar Observatory (NSO) KPVT observations under a grant from the National Science Foundation (NSF). Solar wind data utilized for this project is provided on the Internet at http://nssdc.gsfc.nasa.gov/omniweb/. This work is carried out through the NSO Research Experiences for Undergraduate (REU) site program, which is co-funded by the Department of Defense in partnership with the National Science Foundation REU Program. This research was supported in part by the Office of Naval Research Grant N00014-91-J-1040. The NSO is operated by AURA, Inc. under a cooperative agreement with the NSF.

  16. Solar wind density intercomparisons on the WIND spacecraft using WAVES and SWE experiments

    Microsoft Academic Search

    M. Maksimovic; J.-L. Bougeret; C. Perche; J. T. Steinberg; A. J. Lazarus; A. F. Viñas; R. J. Fitzenreiter

    1998-01-01

    We present solar wind density comparisons using three different instruments on the WIND spacecraft: The thermal noise receiver (TNR) on the WAVES experiment which yields the total electron density from the detection and the analysis of the electron plasma peak; the SWE Faraday cup detectors which measure ion energy per charge spectra and yield the proton and alpha particle densities

  17. 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.

  18. Solar cosmic ray, solar wind, solar flare, and neutron albedo measurements, part C

    NASA Technical Reports Server (NTRS)

    Burnett, D.; Hohenberg, C.; Maurette, M.; Monnin, M.; Walker, R.; Wollum, D.

    1972-01-01

    All mineral detectors exposed on Apollo 16 had high surface track densities probably produced by a solar flare that occurred during the mission. The heavy ions followed a power law spectrum with exponent approximately 3 down to approximately 200 KeV/nucleon. The abundance of low-energy particle tracks observed in this flare may explain the high track densities observed in lunar dust grains. Pristine heavy-particle tracks in feldspar give long tracks. Shallow pits similar to those expected from extremely heavy solar wind ions were observed in about the expected number. Initial results give a low apparent value of neutron albedo relative to theory.

  19. The characteristics of sharp (small-scale) boundaries of solar wind plasma and magnetic field structures

    E-print Network

    Richardson, John

    The characteristics of sharp (small-scale) boundaries of solar wind plasma and magnetic field investigate properties of large (>20%) and sharp (solar wind ion flux changes using INTERBALL-1 are the boundaries of small-scale and mid- dle-scale solar wind structures. We describe the behavior of the solar

  20. Simulation and optimum design of hybrid solar-wind and solar-wind-diesel power generation systems

    NASA Astrophysics Data System (ADS)

    Zhou, Wei

    Solar and wind energy systems are considered as promising power generating sources due to its availability and topological advantages in local power generations. However, a drawback, common to solar and wind options, is their unpredictable nature and dependence on weather changes, both of these energy systems would have to be oversized to make them completely reliable. Fortunately, the problems caused by variable nature of these resources can be partially overcome by integrating these two resources in a proper combination to form a hybrid system. However, with the increased complexity in comparison with single energy systems, optimum design of hybrid system becomes more complicated. In order to efficiently and economically utilize the renewable energy resources, one optimal sizing method is necessary. This thesis developed an optimal sizing method to find the global optimum configuration of stand-alone hybrid (both solar-wind and solar-wind-diesel) power generation systems. By using Genetic Algorithm (GA), the optimal sizing method was developed to calculate the system optimum configuration which offers to guarantee the lowest investment with full use of the PV array, wind turbine and battery bank. For the hybrid solar-wind system, the optimal sizing method is developed based on the Loss of Power Supply Probability (LPSP) and the Annualized Cost of System (ACS) concepts. The optimization procedure aims to find the configuration that yields the best compromise between the two considered objectives: LPSP and ACS. The decision variables, which need to be optimized in the optimization process, are the PV module capacity, wind turbine capacity, battery capacity, PV module slope angle and wind turbine installation height. For the hybrid solar-wind-diesel system, minimization of the system cost is achieved not only by selecting an appropriate system configuration, but also by finding a suitable control strategy (starting and stopping point) of the diesel generator. The optimal sizing method was developed to find the system optimum configuration and settings that can achieve the custom-required Renewable Energy Fraction (fRE) of the system with minimum Annualized Cost of System (ACS). Du to the need for optimum design of the hybrid systems, an analysis of local weather conditions (solar radiation and wind speed) was carried out for the potential installation site, and mathematical simulation of the hybrid systems' components was also carried out including PV array, wind turbine and battery bank. By statistically analyzing the long-term hourly solar and wind speed data, Hong Kong area is found to have favorite solar and wind power resources compared with other areas, which validates the practical applications in Hong Kong and Guangdong area. Simulation of PV array performance includes three main parts: modeling of the maximum power output of the PV array, calculation of the total solar radiation on any tilted surface with any orientations, and PV module temperature predictions. Five parameters are introduced to account for the complex dependence of PV array performance upon solar radiation intensities and PV module temperatures. The developed simulation model was validated by using the field-measured data from one existing building-integrated photovoltaic system (BIPV) in Hong Kong, and good simulation performance of the model was achieved. Lead-acid batteries used in hybrid systems operate under very specific conditions, which often cause difficulties to predict when energy will be extracted from or supplied to the battery. In this thesis, the lead-acid battery performance is simulated by three different characteristics: battery state of charge (SOC), battery floating charge voltage and the expected battery lifetime. Good agreements were found between the predicted values and the field-measured data of a hybrid solar-wind project. At last, one 19.8kW hybrid solar-wind power generation project, designed by the optimal sizing method and set up to supply power for a telecommunication relay station on a remote island of Guangdong pr

  1. The 'wind-wall' - An integrated wind\\/solar system

    Microsoft Academic Search

    J. C. McVeigh; G. W. W. Pontin

    1977-01-01

    Design of an integrated system combining a windmill system and solar panels is discussed. The system is intended for power supply to residential areas. A bank of fixed ducted windmills and batteries of solar collectors sharing a common overall site are considered in an arrangement providing hot water and space heating. A water reservoir heat storage system, basic electrical system,

  2. SOLAR WIND HELIUM ABUNDANCE AS A FUNCTION OF SPEED AND HELIOGRAPHIC LATITUDE: VARIATION THROUGH A SOLAR CYCLE

    E-print Network

    Richardson, John

    SOLAR WIND HELIUM ABUNDANCE AS A FUNCTION OF SPEED AND HELIOGRAPHIC LATITUDE: VARIATION THROUGH of the variation of the relative abundance of helium to hydrogen in the solar wind as a function of solar wind theoretical work in which enhancements of coronal helium lead to stagnation of the escaping proton flux

  3. Rosetta observations of solar wind deflection in the coma

    NASA Astrophysics Data System (ADS)

    Broiles, Thomas; Burch, James; Clark, George; Goldstein, Raymond; Koenders, Christoph; Mandt, Kathleen; Mokashi, Prachet; Samara, Marilia

    2015-04-01

    Until recently, study of the solar wind around comets was limited to remote observations and brief in-situ encounters. With the arrival of Rosetta at the comet Churyumov-Gerasimenko (CG), we have had near constant solar wind observations at the comet for over 6 months. This is an unprecedented opportunity to study this dynamic interaction over time. Neutral atoms produced by the comet become ionized through photoionization or charge-exchange with the solar wind. The freshly ionized particles experience v x B electric field and begin to gyrate around the interplanetary magnetic field. Currently, CG is ~2.6 AU from the Sun, and as of this writing, neutral production is still relatively low. Consequently, most pickup ions are produced locally (< few hundred kilometers), and a diamagnetic cavity may not exist. Moreover, neutral production is variable and changes over the comet's rotational period. We find the following: 1) The solar wind is heavily deflected near the comet (in some cases >45° away from the anti-sunward direction). 2) The solar wind helium experiences less deflection than the protons. 3) The periodicity of the deflection is highly variable, and can vary over minutes or hours. From these results, we conclude that the solar wind is deflected by a mechanism very close to the comet. We suggest the following possibilities: 1) The solar wind could be deflected by a Lorenz force in the opposite direction to that experienced by the pickup ions, which would also conserve the momentum of the two fluid system. This would explain why solar wind protons are more strongly deflected than the heavier alpha particles. Additionally, this would explain the periodicity of the deflections, which would react to changes in the interplanetary magnetic field. 2) The solar wind deflection might occur from strong charging of comet's nucleus. In which case, the nucleus may charge both positively or negatively. The nucleus could charge positively due photoionization of the surface, but could also charge negatively due to the high electron fluxes that are regularly observed. This mechanism might also explain the preferential deflection of lighter ions and the variable periodicity of the deflection.

  4. 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

    2007-12-01

    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. PMID:18063784

  5. THE TURBULENT CASCADE AND PROTON HEATING IN THE SOLAR WIND DURING SOLAR MINIMUM

    SciTech Connect

    Coburn, Jesse T.; Smith, Charles W.; Vasquez, Bernard J. [Physics Department and Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH (United States); Stawarz, Joshua E. [Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, Boulder, CA (United States); Forman, Miriam A., E-mail: jtu46@wildcats.unh.edu, E-mail: Charles.Smith@unh.edu, E-mail: Bernie.Vasquez@unh.edu, E-mail: Joshua.Stawarz@Colorado.edu, E-mail: Miriam.Forman@sunysb.edu [Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, NY (United States)

    2012-08-01

    The recently protracted solar minimum provided years of interplanetary data that were largely absent in any association with observed large-scale transient behavior on the Sun. With large-scale shear at 1 AU generally isolated to corotating interaction regions, it is reasonable to ask whether the solar wind is significantly turbulent at this time. We perform a series of third-moment analyses using data from the Advanced Composition Explorer. We show that the solar wind at 1 AU is just as turbulent as at any other time in the solar cycle. Specifically, the turbulent cascade of energy scales in the same manner proportional to the product of wind speed and temperature. Energy cascade rates during solar minimum average a factor of 2-4 higher than during solar maximum, but we contend that this is likely the result of having a different admixture of high-latitude sources.

  6. The abundances of elements and isotopes in the solar wind

    NASA Technical Reports Server (NTRS)

    Gloeckler, George; Geiss, Johannes

    1989-01-01

    Solar wind abundances have now been measured for eleven elements and the isotopes of the noble gases. Aside from solar wind protons and alpha particles, which have been studied extensively since the 1960's, information for heavier elements is limited. Nevertheless, two effects stand out. First is the enrichment of abundances of elements with low first ionization potential (FIP), most likely the combined result of an atom-ion separation process in the upper chromosphere, and a marginal coupling of low-charge-state heavy ions to protons and alphas during the acceleration of the solar wind. Second, there is variability in the solar wind composition over a whole range of time scales. Recent measurements carried out in the earth's magnetosheath during times that included high-speed coronal-hole-associated flows indicate a significantly lower overabundance of low FIP elements. Given the fact that the He/H ratio is remarkably constant in the coronal hole solar wind, this result suggests that both enrichment and variability are reduced in such flows.

  7. Magnetic field gradients in solar wind plasma and geophysics periods

    E-print Network

    A. Bershadskii

    2006-11-16

    Using recent data obtained by Advanced Composition Explorer (ACE) the pumping scale of the magnetic field gradients of the solar wind plasma has been calculated. This pumping scale is found to be equal to 24h $\\pm$ 2h. The ACE spacecraft orbits at the L1 libration point which is a point of Earth-Sun gravitational equilibrium about 1.5 million km from Earth. Since the Earth's magnetosphere extends into the vacuum of space from approximately 80 to 60,000 kilometers on the side toward the Sun the pumping scale cannot be a consequence of the 24h-period of the Earth's rotation. Vise versa, a speculation is suggested that for the very long time of the coexistence of Earth and of the solar wind the weak interaction between the solar wind and Earth could lead to stochastic synchronization between the Earth's rotation and the pumping scale of the solar wind magnetic field gradients. This synchronization could transform an original period of the Earth's rotation to the period close to the pumping scale of the solar wind magnetic field gradients.

  8. The quiet solar wind. [proton and magnetic properties

    NASA Technical Reports Server (NTRS)

    Neugebauer, M.

    1976-01-01

    Data from nine spacecraft are combined to study the properties of solar wind protons and the interplanetary magnetic field under unusual conditions that proton speed, density, and temperature variations are small over periods comparable to the solar wind expansion time. From the 14 quiet intervals studied it is determined that (1) the square root of T versus velocity relation is less steep than was calculated from long-term-averaged or 3-hour quiet data; (2) the density varies approximately as the inverse square of the velocity; however, the data scatter is large, and an alternative interpretation is that mass flux is constant for velocities over about 400 km/s, in agreement with earlier studies; (3) the magnitude of the interplanetary magnetic field is independent of solar wind speed and density; and (4) the average field direction varies with the solar wind speed as predicted by Parker's spiral model. The intercalibration of solar wind measurements by different spacecraft is discussed in an appendix.

  9. Direct evidence for kinetic effects associated with solar wind reconnection

    NASA Astrophysics Data System (ADS)

    Xu, Xiaojun; Wang, Yi; Wei, Fengsi; Feng, Xueshang; Deng, Xiaohua; Ma, Yonghui; Zhou, Meng; Pang, Ye; Wong, Hon-Cheng

    2015-01-01

    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.

  10. SOLAR WIND MODELING WITH TURBULENCE TRANSPORT AND HEATING

    SciTech Connect

    Usmanov, Arcadi V.; Goldstein, Melvyn L. [Code 673, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Matthaeus, William H. [Department of Physics and Astronomy and Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Breech, Benjamin A., E-mail: arcadi.usmanov@nasa.gov [NASA Postdoctoral Program, Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)

    2011-02-01

    We have developed an axisymmetric steady-state solar wind model that describes properties of the large-scale solar wind, interplanetary magnetic field, and turbulence throughout the heliosphere from 0.3 AU to 100 AU. The model is based on numerical solutions of large-scale Reynolds-averaged magnetohydrodynamic equations coupled with a set of small-scale transport equations for the turbulence energy, normalized cross helicity, and correlation scale. The combined set of time-dependent equations is solved in the frame of reference corotating with the Sun using a time-relaxation method. We use the model to study the self-consistent interaction between the large-scale solar wind and smaller-scale turbulence and the role of the turbulence in the large-scale structure and temperature distribution in the solar wind. To illuminate the roles of the turbulent cascade and the pickup protons in heating the solar wind depending on the heliocentric distance, we compare the model results with and without turbulence/pickup protons. The variations of plasma temperature in the outer heliosphere are compared with Ulysses and Voyager 2 observations.

  11. Fast solar wind monitoring available: BMSW in operation

    NASA Astrophysics Data System (ADS)

    Šafránková, J.; N?me?ek, Z.; P?ech, L.; Zastenker, G.

    2013-06-01

    The Spektr-R spacecraft was launched on a Zenit-3F rocket into an 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 investigations of distant sources of electromagnetic emissions but, as a supporting measurement, the spacecraft carries a complex of instruments for solar wind monitoring because it will spend there ~ 8 days out of the 9-day orbit. The main task of the solar wind monitor (BMSW) is to provide fast measurements of the solar wind density, velocity, and temperature with a maximum time resolution of 31 ms. Such time resolution was obtained using simultaneous measurements of several Faraday cups oriented permanently nearly in the solar wind direction. In this paper, we describe briefly basic principles of the BMSWoperation, and show a few examples its observations. We present frequency spectra of the solar wind turbulence at the kinetic scale and an example of high-frequency waves associated with an IP shock.

  12. Interaction of the solar wind with the moon.

    NASA Technical Reports Server (NTRS)

    Ness, N. F.

    1972-01-01

    During its orbit about the earth, the moon is located in the interplanetary medium or in the geomagnetosheath-geomagnetotail formed by the solar wind interaction with earth. In the tail, no evidence is found for a lunar magnetic field. In the interplanetary medium, no evidence exists for a bow shock or a trailing shock, although a well defined plasma wake region is observed in the anti-solar wind direction. The moon absorbs the solar wind plasma that strikes its surface and creates a void region or cavity in the flow. The observed lunar Mach cone gives evidence for the anisotropic propagation of waves in the magnetized collisionless warm plasma of the solar wind. The transmission of microstructural discontinuities in the interplanetary medium past the moon shows little distortion, indicating a low effective electrical conductivity of the lunar body. Fluctuations of the interplanetary magnetic field upstream from the plasma wake are stimulated by the disturbed conditions in that region. The moon behaves like a cold, nonmagnetic, fully absorbing dielectric sphere in the solar wind flow.

  13. Direct evidence for kinetic effects associated with solar wind reconnection

    PubMed Central

    Xu, Xiaojun; Wang, Yi; Wei, Fengsi; Feng, Xueshang; Deng, Xiaohua; Ma, Yonghui; Zhou, Meng; Pang, Ye; Wong, Hon-Cheng

    2015-01-01

    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. PMID:25628139

  14. The Importance of Suprathermal Electrons in the Solar Wind

    NASA Astrophysics Data System (ADS)

    LE CHAT, G.; Meyer-Vernet, N.; Pantellini, F. G. E.; Issautier, K.; Moncuquet, M.

    2014-12-01

    Non-Gaussian distributions are ubiquitous in systems having long-range interactions, from real-world networks to astrophysical plasmas. The corona and solar wind are no exception. In this review, we concentrate on the corona and solar wind electrons, whose suprathermal tail governs heat transport and plays a crucial role in the temperature structure and wind production, as first suggested thirty years ago by Olbert and confirmed by a large number of subsequent studies. These non-thermal electrons have been measured in both the corona and solar wind, and are a direct consequence of the fast increase with speed of the Coulomb free-path, compared to the pressure scale-height. This situation has four important consequences: (1) the fluid description, on which the vast majority of solar wind models are based is inadequate; (2) the heat flux is NOT given by the classical Spitzer-Härm expression in the corona and solar wind; (3) for most non-thermal distributions (except the convenient and fashionable Kappa distribution), the fraction of supra-thermal electrons increases with altitude in the corona because of velocity filtration; for example, with a sum of Maxwellians, the hotter the population, the larger the increase with altitude of its fractional contribution; (4) ad-hoc heat addition - assumed in most models, is not necessarily required to produce the observed variation in temperature and the wind acceleration. We will shortly review the observed electron velocity distributions together with the theoretical expectations, the major role of the electric field and the consequences on the heat flux, the temperature structure and the wind acceleration.

  15. Solar Wind Drivers of Storm-Time Radiation Belt Variations

    NASA Astrophysics Data System (ADS)

    Kilpua, Emilia; Hietala, Heli; Turner, Drew; Koskinen, Hannu; Pulkkinen, Tuija; Rodriguez, Juan; Reeves, Geoffrey; Claudepierre, Seth; Spence, Harlan

    2015-04-01

    It is an outstanding question why some storms result in an increase of the outer radiation belt electron fluxes, while others deplete them or produce no change. One approach to this problem is to look at differences in the large-scale solar wind storm drivers. The drivers have traditionally been classified to Stream Interaction Regions (SIRs) and Interplanetary Coronal Mass Ejections (ICMEs). However, ICMEs and SIRs are complex structures: SIRs consist of a slow stream followed by a turbulent, higher pressure interface region and then a faster stream. The core of the ICME is an ejecta. If the mass ejection is fast enough, it can drive a shock in front of it. This leads to the formation of a sheath region between the interplanetary shock and the leading edge of the ejecta. Fast streams that are integral part of SIR may or may not follow the ICME. The solar wind properties, and hence, the magnetospheric driving of different substructures in SIRs and ICMEs are very distinct. In this work we will investigate the radiation belt response to different storm drivers by combining near-Earth solar wind observations, long-term geosynchronous observations from GOES spanning over 1.5 solar cycles (1995-2013) and the state-of-the art Van Allen Probe data. Our study uses superposed epoch analysis with multiple reference times and we expand/contract each solar wind substructure to the population mean. This novel approach allows us to determine the typical evolution of the electron fluxes during each solar wind structure. Our results show that the separation of the effects from different parts of the ICME and SIRs will be crucial for understanding how radiation belt electrons react to different solar wind driving conditions.

  16. Parametric decay of Alfvén wave in the solar wind acceleration

    NASA Astrophysics Data System (ADS)

    Tenerani, Anna; Velli, Marco

    2014-05-01

    Large amplitude Alfvén waves are commonly observed in the solar wind and it is widely believed that these magnetic waves may contribute to the solar wind heating and acceleration through turbulent dissipation and ponderomotive force. In-situ observations show that a nonlinear cascade of Alfvén waves, mainly propagating outward, is taking place, and that it evolves with heliocentric distance. In spite of the well defined observational signatures, the evolution of such Alfvénic turbulence in the solar wind is still a matter under debate. Parametric decay of large amplitude Alfvén waves has been invoked as a possible driver of such evolution: the decay of an outward Alfvén wave into an inward one and, on the other hand, into a sound wave which naturally tends to steepen, provides the key ingredients for the onset of a turbulent cascade as well as for energy dissipation. In spite of many theoretical and numerical studies on the parametric decay instability, possible effects of the solar wind radial expansion have not yet been taken into account. However, the expansion of the underlying solar atmosphere is an indiscernible element to the extent that the observed decrease in overall rms energies is well accounted for by expansion effects. We provide here a study on the onset and evolution of the parametric decay within the Accelerating Expanding Box model. This model takes into account the effects of the accelerating radial expansion of the solar wind, including the crossing of the critical Alfvén point, where wave amplitudes are expected to peak. The aim is to inspect if and in which manner the non-uniform radial expansion of the solar wind affects the growth and evolution of the instability itself and in which way it may affect the alfvénic spectrum at large heliocentric distances.

  17. A Floor in the Solar Wind Magnetic Field

    NASA Astrophysics Data System (ADS)

    Svalgaard, L.; Cliver, E. W.

    2007-06-01

    Long-term (~130 years) reconstruction of the interplanetary magnetic field (IMF) based on geomagnetic indices indicates that the solar wind magnetic field strength has a ``floor,'' a baseline value in annual averages that it approaches at each 11 yr solar minimum. In the ecliptic plane at 1 AU, the IMF floor is ~4.6 nT, a value substantiated by direct solar wind measurements and cosmogenic nuclei data. At high heliolatitudes, Ulysses measured a constant radial field with a magnitude (normalized to 1 AU) of ~3.2 nT during solar minimum conditions in ~1995 when the observed solar polar fields were ~100 ?T and in 2006 when the polar fields were ~60 ?T, as well as for solar maximum conditions in 2001 when the polar fields were close to zero. We identify the floor with a constant (over centuries) baseline open magnetic flux at 1 AU of ~4×1014 Wb, corresponding to a constant strength (~1011 A) of the heliospheric current. Solar cycle variations of the IMF strength ride on top of the floor. The floor has implications for (1) the solar wind during grand minima-we are given a glimpse of Maunder minimum conditions at every 11 yr minimum; (2) current models of the solar wind-both source surface and MHD models are based on the assumption, invalidated by Ulysses, that the largest scale fields determine the magnitude of the IMF; consequently, these models are unable to reproduce the high-latitude observations; and (3) the use of geomagnetic input data for precursor-type predictions of the coming sunspot maximum-this common practice is rendered doubtful by the observed disconnect between solar polar field strength and heliospheric field strength.

  18. The Storm-Substorm Relationship during Different Solar Wind Conditions

    NASA Astrophysics Data System (ADS)

    Hsu, T. S.; McPherron, R. L.; Chu, X.

    2014-12-01

    Solar-terrestrial coupling is the study of processes which transfer solar wind energy to the magnetosphere creating geomagnetic activity. This coupling depends on properties of the solar wind and particularly on the discrete structures present in the solar wind. These include CMEs, CIRs, and HSS (high speed streams) which have very different characteristics causing different modes of response of the magnetosphere such as magnetic storm, substorms, steady magnetospheric convection (SMC) and others. Among these different modes of response, magnetic storms and substorms are two of the primary ones because they occur frequently and because they can cause considerable problems in technological systems. The differences in solar wind driving conditions during CME, CIR, and HSS provide a good opportunity to examine how the properties of substorms change with solar wind structures and the activity they create. Since the probability of observing these structures is a function of solar cycle phase, the storm-substorm relationship changes with solar cycle phase. It is possible that the nature of solar wind coupling changes with the type of storm, storm intensity, and/or the phase of the storms. The original hypothesis was that a magnetic storm is simply a superposition of substorms. However, some evidences have been found that storms begin to develop before substorms occur. Is substorm occurrence independent of storm development? This would suggest that substorms can be seen in any phase of a storm and even a storm without substorms. There are some recent studies suggest this is possible. However, most of the studies did not take into consideration different solar wind driving conditions. In this study, we will investigate several aspects of the relation of substorms to storms such as: Does the frequency and intensity of substorms change with phase of the solar cycle? Are there differences in these properties between cycles? Are the characteristics of substorms different if they occur within a storm or outside of a storm? Are CME storm time substorms different from CIR storm substorms? Do substorm properties change with phase of the storm?

  19. Origins of the slow and the ubiquitous fast solar wind

    E-print Network

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

    1997-09-03

    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 solar wind. Limits on the flow speed are derived from the Doppler dimming of the resonantly scattered componentof the oxygen 1032 A and 1037 A lines as measured with the UltraViolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory (SOHO). White light images of the corona from the Large Angle Spectroscopic Coronagraph (LASCO) on SOHO taken simultaneously are used to place the Doppler radio scintillation and ultraviolet measurements in the context ofcoronal structures. These combined observations provide the first direct confirmation of the view recently proposed by Woo and Martin (1997) that the slow solar wind is associated with the axes, also known as stalks, of streamers. Furthermore, the ultraviolet observations also show how the fast solar wind is ubiquitous in the inner corona, and that a velocity shear between the fast and slow solar wind develops along the streamer stalks.

  20. Generalized similarity in finite range solar wind magnetohydrodynamic turbulence

    E-print Network

    Chapman, S C

    2009-01-01

    Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. ULYSSES spacecraft solar polar passes at solar minimum provide \\textit{in situ} observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterises this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum -with turbulent fluctuations down by a factor of $\\sim 2$ in power- provides a test of this invariance.

  1. Generalized Similarity in Finite Range Solar Wind Magnetohydrodynamic Turbulence

    SciTech Connect

    Chapman, S. C.; Nicol, R. M. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom)

    2009-12-11

    Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterizes this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum - with turbulent fluctuations down by a factor of approx2 in power - provides a test of this invariance.

  2. Generalized similarity in finite range solar wind magnetohydrodynamic turbulence.

    PubMed

    Chapman, S C; Nicol, R M

    2009-12-11

    Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterizes this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum--with turbulent fluctuations down by a factor of approximately 2 in power--provides a test of this invariance. PMID:20366193

  3. Ulysses solar wind plasma observations at high southerly latitudes.

    PubMed

    Phillips, J L; Bame, S J; Feldman, W C; Gosling, J T; Hammond, C M; McComas, D J; Goldstein, B E; Neugebauer, M; Scime, E E; Suess, S T

    1995-05-19

    Solar wind plasma observations made by the Ulysses spacecraft through -80.2 degrees solar latitude and continuing equatorward to -40.1 degrees are summarized. Recurrent high-speed streams and corotating interaction regions dominated at middle latitudes. The speed of the solar wind was typically 700 to 800 kilometers per second poleward of -35 degrees . Corotating reverse shocks persisted farther south than did forward shocks because of the tilt of the heliomagnetic streamer belt. Sporadic coronal mass ejections were seen as far south as -60.5 degrees . Proton temperature was higher and the electron strahl was broader at higher latitudes. The high-latitude wind contained compressional, pressure-balanced, and Alfvénic structures. PMID:17774231

  4. Solar wind flow past Venus - Theory and comparisons

    NASA Astrophysics Data System (ADS)

    Spreiter, J. R.; Stahara, S. S.

    1980-12-01

    Advanced computational procedures are applied to an improved model of solar wind flow past Venus to calculate the locations of the ionopause and bow wave and the properties of the flowing ionosheath plasma in the intervening region. The theoretical method is based on a single-fluid, steady, dissipationless, magneto-hydrodynamic continuum model and is appropriate for the calculation of axisymmetric supersonic, super-Alfvenic solar wind flow past a nonmagnetic planet possessing a sufficiently dense ionosphere to stand off the flowing plasma above the subsolar point and elsewhere. Determination of time histories of plasma and magnetic field properties along an arbitrary spacecraft trajectory and provision for an arbitrary oncoming direction of the interplanetary solar wind have been incorporated in the model. An outline is provided of the underlying theory and computational procedures, and sample comparisons of the results are presented with observations from the Pioneer Venus orbiter.

  5. Energy coupling between the solar wind and the magnetosphere

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1981-01-01

    A description is given of the path leading to the first approximation expression for the solar wind-magnetosphere energy coupling function (epsilon), which correlates well with the total energy consumption rate (U sub T) of the magnetosphere. It is shown that epsilon is the primary factor controlling the time development of magnetospheric substorms and storms. The finding of this particular expression epsilon indicates how the solar wind couples its energy to the magnetosphere; the solar wind and the magnetosphere make up a dynamo. In fact, the power generated by the dynamo can be identified as epsilon through the use of a dimensional analysis. In addition, the finding of epsilon suggests that the magnetosphere is closer to a directly driven system than to an unloading system which stores the generated energy before converting it to substorm and storm energies. The finding of epsilon and its implications is considered to have significantly advanced and improved the understanding of magnetospheric processes.

  6. Kinetics of Electrons in the Corona and Solar Wind

    NASA Astrophysics Data System (ADS)

    Vocks, C.; Mann, G.

    2003-09-01

    The velocity distribution functions (VDFs) of electrons as measured in the solar wind show pronounced deviations from a Maxwellian. They seem to be composed of a thermal core and energetic tails, called halo. These VDFs can be fitted very well by kappa distributions. The formation of the energetic tails in the corona or in the solar wind is investigated. The relaxation of a kappa distribution under the influence of Coulomb collisions in the coronal plasma is calculated. This allows an estimation if the energetic tails of the VDFs can be formed in the corona. Resonant interaction between the electrons and electron cyclotron waves is suggested as a mechanism for the generation of the energetic tails. A kinetic model for electrons is presented. Coulomb collisions and wave-particle interactions are considered. With this model, electron VDFs can be calculated from the transition region up into the solar wind.

  7. Lunar fossil magnetism and perturbations of the solar wind.

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.; Mihalov, J. D.

    1972-01-01

    Perturbations of the solar wind downstream of the moon and lying outside of the rarefaction wave that defines the diamagnetic cavity are used to define possible source regions comprised of intrinsically magnetized areas of the moon. A map of the moon is constructed showing that a model in which the sources are exposed to the grazing solar wind during the lunation yields a selenographically invariant set of regions strongly favoring the lunar highlands over the maria. An alternative model with the source due to electromagnetic induction is explored. The ages of the field sources should be consistent with those based on the basalt ages and possibly far older if the sources are connected with the formation of the highland rocks themselves. The perturbations are tentatively identified as weak shock waves, and a Mach angle in accord with nominal values for the solar wind is found.

  8. Magnetic measurements of the solar wind interaction with the moon

    NASA Technical Reports Server (NTRS)

    Lichtenstein, B. R.; Coleman, P. J., Jr.; Russell, C. T.

    1973-01-01

    The magnetic signature of the interaction between the moon and the solar wind (as observed by the Apollo 15 subsatellite) is an enhanced field directly behind the moon, bounded on either side by two dips in the field strength. On occasion, compressions of the field strength are observed external to either one or sometimes both of these dips. Theories of the interaction postulate either that these compressions are a general feature of the solar wind-moon interaction modulated by changes in the solar wind parameters or that they are associated with the appearance of specific lunar regions at the limbs. The measurements of the lunar magnetic field with the Apollo 15 and 16 subsatellites, the mapping of projected source positions of limb compressions onto the lunar surface, and the study of the persistence of limb compressions supports the hypothesis that limb compressions are formed when regions of high magnetization are at the lunar limbs.

  9. Solar Wind Observations from 10 to 30 AU Measured With The New Horizons Solar Wind Around Pluto (SWAP) Instrument

    NASA Astrophysics Data System (ADS)

    Elliott, H. A.; McComas, D. J.; Valek, P. W.; Nicolaou, G.; Bagenal, F.; Delamere, P. A.; Livadiotis, G.

    2014-12-01

    Beginning in 2012 the New Horizons mission to Pluto began collecting solar wind observations during the spacecraft hibernation greatly increasing the solar wind coverage. We have extensively analyzed both the laboratory and flight calibration measurements for the Solar Wind Around Pluto (SWAP) instrument to produce a data set of solar wind observations at times when the New Horizons spacecraft is spinning. This full data set spans from 10 to 30 AU, and the improved coverage portion spans from 20- 30 AU. Coincidently, in 2012 and 2013 the ACE, STEREO A, and STEREO B were well separated in longitude. We compare the New Horizons speeds with propagated 1 AU speed measurements, and find many of the largest scale structures persist beyond 20 AU. The New Horizons solar wind coverage between 20 and 30 AU is now extensive enough to examine the temperature-speed relationship and compare that to the relationship found in the inner heliosphere and to that in the Voyager 2 observations. Upon initial examination we also find a temperature-speed relationship that persists in the 20-30 AU distance range.

  10. Turbulent Heating and Wave Pressure in Solar Wind Acceleration Modeling: New Insights to Empirical Forecasting of the Solar Wind

    NASA Astrophysics Data System (ADS)

    Woolsey, L. N.; Cranmer, S. R.

    2013-12-01

    The study of solar wind acceleration has made several important advances recently due to improvements in modeling techniques. Existing code and simulations test the competing theories for coronal heating, which include reconnection/loop-opening (RLO) models and wave/turbulence-driven (WTD) models. In order to compare and contrast the validity of these theories, we need flexible tools that predict the emergent solar wind properties from a wide range of coronal magnetic field structures such as coronal holes, pseudostreamers, and helmet streamers. ZEPHYR (Cranmer et al. 2007) is a one-dimensional magnetohydrodynamics code that includes Alfven wave generation and reflection and the resulting turbulent heating to accelerate solar wind in open flux tubes. We present the ZEPHYR output for a wide range of magnetic field geometries to show the effect of the magnetic field profiles on wind properties. We also investigate the competing acceleration mechanisms found in ZEPHYR to determine the relative importance of increased gas pressure from turbulent heating and the separate pressure source from the Alfven waves. To do so, we developed a code that will become publicly available for solar wind prediction. This code, TEMPEST, provides an outflow solution based on only one input: the magnetic field strength as a function of height above the photosphere. It uses correlations found in ZEPHYR between the magnetic field strength at the source surface and the temperature profile of the outflow solution to compute the wind speed profile based on the increased gas pressure from turbulent heating. With this initial solution, TEMPEST then adds in the Alfven wave pressure term to the modified Parker equation and iterates to find a stable solution for the wind speed. This code, therefore, can make predictions of the wind speeds that will be observed at 1 AU based on extrapolations from magnetogram data, providing a useful tool for empirical forecasting of the sol! ar wind.

  11. Agua Caliente Wind/Solar Project at Whitewater Ranch

    SciTech Connect

    Hooks, Todd; Stewart, Royce

    2014-12-16

    Agua Caliente Band of Cahuilla Indians (ACBCI) was awarded a grant by the Department of Energy (DOE) to study the feasibility of a wind and/or solar renewable energy project at the Whitewater Ranch (WWR) property of ACBCI. Red Mountain Energy Partners (RMEP) was engaged to conduct the study. The ACBCI tribal lands in the Coachella Valley have very rich renewable energy resources. The tribe has undertaken several studies to more fully understand the options available to them if they were to move forward with one or more renewable energy projects. With respect to the resources, the WWR property clearly has excellent wind and solar resources. The DOE National Renewable Energy Laboratory (NREL) has continued to upgrade and refine their library of resource maps. The newer, more precise maps quantify the resources as among the best in the world. The wind and solar technology available for deployment is also being improved. Both are reducing their costs to the point of being at or below the costs of fossil fuels. Technologies for energy storage and microgrids are also improving quickly and present additional ways to increase the wind and/or solar energy retained for later use with the network management flexibility to provide power to the appropriate locations when needed. As a result, renewable resources continue to gain more market share. The transitioning to renewables as the major resources for power will take some time as the conversion is complex and can have negative impacts if not managed well. While the economics for wind and solar systems continue to improve, the robustness of the WWR site was validated by the repeated queries of developers to place wind and/or solar there. The robust resources and improving technologies portends toward WWR land as a renewable energy site. The business case, however, is not so clear, especially when the potential investment portfolio for ACBCI has several very beneficial and profitable alternatives.

  12. The turbulent cascade and proton heating in the solar wind during solar minimum

    SciTech Connect

    Coburn, Jesse T.; Smith, Charles W.; Vasquez, Bernard J. [Physics Department and Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire (United States); Stawarz, Joshua E. [Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, Boulder, Colorado (United States); Forman, Miriam A. [Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York (United States)

    2013-06-13

    Solar wind measurements at 1 AU during the recent solar minimum and previous studies of solar maximum provide an opportunity to study the effects of the changing solar cycle on in situ heating. Our interest is to compare the levels of activity associated with turbulence and proton heating. Large-scale shears in the flow caused by transient activity are a source that drives turbulence that heats the solar wind, but as the solar cycle progresses the dynamics that drive the turbulence and heat the medium are likely to change. The application of third-moment theory to Advanced Composition Explorer (ACE) data gives the turbulent energy cascade rate which is not seen to vary with the solar cycle. Likewise, an empirical heating rate shows no significan changes in proton heating over the cycle.

  13. SOLAR WIND MAGNETOHYDRODYNAMICS TURBULENCE: ANOMALOUS SCALING AND ROLE OF INTERMITTENCY

    SciTech Connect

    Salem, C.; Bale, S. D. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Mangeney, A. [LESIA, Observatoire de Paris-Meudon, F-92195 Meudon (France); Veltri, P. [Dipartimento di Fisica, Universita della Calabria, Rende (Italy)], E-mail: salem@ssl.berkeley.edu

    2009-09-01

    In this paper, we present a study of the scaling properties and intermittency of solar wind MHD turbulence based on the use of wavelet transforms. More specifically, we use the Haar Wavelet transform on simultaneous 3 s resolution particle and magnetic field data from the Wind spacecraft, to investigate anomalous scaling and intermittency effects of both magnetic field and solar wind velocity fluctuations in the inertial range. For this purpose, we calculated spectra, structure functions, and probability distribution functions. We show that this powerful wavelet technique allows for a systematic elimination of intermittency effects on spectra and structure functions and thus for a clear determination of the actual scaling properties in the inertial range. The scaling of the magnetic field and the velocity fluctuations are found to be fundamentally different. Moreover, when the most intermittent structures superposed to the standard fluctuations are removed, simple statistics are recovered. The magnetic field and the velocity fluctuations exhibit a well-defined, although different, monofractal behavior, following a Kolmogorov -5/3 scaling and a Iroshnikov-Kraichnan -3/2 scaling, respectively. The multifractal properties of solar wind turbulence appear to be determined by the presence of those most intermittent structures. Finally, our wavelet technique also allows for a direct and systematic identification of the most active, singular structures responsible for the intermittency in the solar wind.

  14. Source reliability in a combined wind-solar-hydro system

    NASA Astrophysics Data System (ADS)

    Traca de Almeida, A.; Martins, A.; Jesus, H.; Climaco, J.

    1983-06-01

    The results of an examination of the feasibility of using coupled wind-solar-hydro power generation systems to provide all of Portugal's electricity by the year 2000 are reported. Portugal used 15.6 TWh of electricity in 1981, of which hydro supplied 10 TWh. Demand is expected to reach 34 TWh in 2000 AD. The full development of hydropower resource would furnish 18 TWh and a storage capacity of 4.5 TWh. The installed hydro system could meet the peak demand of 6 GW, while solar cells and wind turbines must produce 16 TWh annually plus a reserve. The Growian wind turbine, 100 m tall, is considered for its 2.2 MW output. A coastal strip of wind turbines 150 x 20 km, with 1 km spacing between the machines, would be needed to produce 5.4 GW of power. Partially tracking solar cell arrays generating 9.4 GW of electricity would require an area of 100 sq km. Computer simulations of the annual rainfall, combined with projections of the variations in wind-solar output, demonstrates that a reserve margin of 1.20 will be necessary. The costs of installation of the renewable energy converters are estimated at about three times that currently necessary for obtaining the same capacity from fission power plants, although the situation may change due to import and technical considerations.

  15. Imaging the Solar Wind with SoloHI

    NASA Astrophysics Data System (ADS)

    Howard, R. A.; Vourlidas, A.; Plunkett, S. P.; Korendyke, C. M.; McMullin, D. R.; Liewer, P. C.; Velli, M. M.; Solohi

    2010-12-01

    Imaging outflows in the corona have been observed with the SOHO/LASCO instrument, since 1996. With the launch of the STEREO mission in 2006, these outflows can be followed into the heliosphere, with the SECCHI/Heliospheric Imager. For the Solar Orbiter mission, we have proposed an instrument called the Solar Orbiter Heliospheric Imager (SoloHI) to be able to image the solar wind and the density fluctuations in the wind and thus provide the link between the in-situ and remote sensing measurements. The nature of the Thomson scattering process integrates along a particular look direction but the scattering is a maximum on the Thomson sphere - the locus of points that form a right angle between the look direction and the solar vector. The experience from SECCHI/HI shows that the density fluctuations are easily visible and can be tracked back into the low corona, enabling a coupling between the solar wind plasma crossing the spacecraft and the source region in the corona. However, the SECCHI/HI observations have low cadence and long integration times. As a new observing mode for SoloHI, we have implemented a capability to readout a subset of the image at a time cadence of about 1 second. Thus small scale fluctuations can be observed in addition to the large scale fluctuations observed from SECCHI/HI. This will enable us to determine the spectral index of the density fluctuations over an unprecedented range of heights (from 5 to 135 Rsun) to compare with the in-situ determinations of the spectral index. This may indicate whether the fluctuations are generated close to the sun and convected out by the solar wind or are generated within the solar wind.

  16. Compressive turbulent cascade and heating in the solar wind

    SciTech Connect

    Marino, R. [Dipartimento di Fisica, Universita della Calabria, Ponte Bucci 31C, I-87036 Rende (Italy); University of Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, B.P. 4229, 06304 Nice Cedex 4 (France); Sorriso-Valvo, L. [Liquid Crystal Laboratory, INFM/CNR, Ponte Bucci 33B, I-87036 Rende (Italy); Carbone, V. [Dipartimento di Fisica, Universita della Calabria, Ponte Bucci 31C, I-87036 Rende (Italy); Noullez, A. [University of Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, B.P. 4229, 06304 Nice Cedex 4 (France); Bruno, R. [INAF-Istituto Fisica Spazio Interplanetario, Rome (Italy)

    2010-03-25

    A turbulent energy cascade has been recently identified in high-latitude solar wind data samples by using a Yaglom-like relation. However, analogous scaling law, suitably modified to take into account compressible fluctuations, has been observed in a much more extended fraction of the same data set recorded by the Ulysses spacecraft. Thus, it seems that large scale density fluctuations, despite their low amplitude, play a major role in the basic scaling properties of turbulence. The compressive turbulent cascade, moreover, seems to be able to supply the energy needed to account for the local heating of the non-adiabatic solar wind.

  17. On the long-tail solar wind electron velocity distribution

    NASA Technical Reports Server (NTRS)

    Shlesinger, Michael F.; Coplan, Michael A.

    1988-01-01

    The role of the log-normal distribution in the description of the high-energy tail of the electron velocity distribution in the solar wind plasma is examined. Specifically, it is shown that the core-halo solar wind distribution function can be understood in terms of a simple phenomenological model of general applicability in which the core has a Maxwellian or normal distribution and the halo a log-normal distribution. In the presence of structures in the interplanetary medium capable of interacting with the electrons, the model predicts a transition at the highest velocities to a secondary halo distribution.

  18. Solar wind kinetic instabilities at small plasma betas

    SciTech Connect

    Ibscher, D., E-mail: ibscher@tp4.rub.de; Schlickeiser, R. [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)] [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2014-02-15

    The ordinary perpendicular mode of drifting bi-Maxwellian plasma particle distributions with and without temperature anisotropy can provide aperiodic instabilities. These instabilities occur if the perpendicular thermal energy is much smaller than the streaming energy. This provides instabilities at small parallel plasma betas ?{sub ?}<1 and temperature anisotropies A?solar wind is unstable, which cannot be explained so far. To clarify if the ordinary perpendicular mode can be responsible for this instability, here we compare measurements in the solar wind with the instability provided by this mode.

  19. Collisional Thermalization of Hydrogen and Helium in Solar Wind Plasma

    NASA Astrophysics Data System (ADS)

    Maruca, B.; Bale, S. D.; Sorriso-Valvo, L.; Kasper, J. C.; Stevens, M. L.

    2013-12-01

    In situ observations of solar wind plasma frequently show the temperature of ?-particles (fully ionized helium), T?, to significantly differ from that of protons (ionized hydrogen), Tp. Many heating processes in the solar wind act preferentially on ?-particles, even as collisions among the plasma's ions act to gradually establish thermal equilibrium. Measurements from the Wind spacecraft's Faraday cups reveal that, at r = 1.0 AU from the Sun, the observed values of the ?-proton relative temperature, ??p ? T?/Tp has a complex, bimodal distribution. Our study employed a simple, analytic model for the evolution of ??p as a function of r. We applied this model to each measurement of ??p from the Wind Faraday cups to infer the corresponding ??p-value closer to the Sun at r = 0.1 AU. The inferred distribution of these ??p-values near the Sun shows no trace of bimodality but is instead consistent with the actions of the known mechanisms for ?-particle preferential heating. This result underscores the importance of collisional processes in the dynamics of the solar wind and suggests that similar mechanisms may lead to preferential ?-particle heating in both slow and fast wind.

  20. CHARACTERIZATION OF TRANSITIONS IN THE SOLAR WIND PARAMETERS

    SciTech Connect

    Perri, S.; Balogh, A., E-mail: silvia.perri@issibern.c, E-mail: a.balogh@imperial.ac.u [International Space Science Institute, Hallerstrasse 6, Bern, CH-3012 (Switzerland)

    2010-02-20

    The distinction between fast and slow solar wind streams and the dynamically evolved interaction regions is reflected in the characteristic fluctuations of both the solar wind and the embedded magnetic field. High-resolution magnetic field data from the Ulysses spacecraft have been analyzed. The observations show rapid variations in the magnetic field components and in the magnetic field strength, suggesting a structured nature of the solar wind at small scales. The typical sizes of fluctuations cover a broad range. If translated to the solar surface, the scales span from the size of granules ({approx}10{sup 3} km) and supergranules ({approx}10{sup 4} km) on the Sun down to {approx}10{sup 2} km and less. The properties of the short time structures change in the different types of solar wind. While fluctuations in fast streams are more homogeneous, slow streams present a bursty behavior in the magnetic field variances, and the regions of transition are characterized by high levels of power in narrow structures around the transitions. The probability density functions of the magnetic field increments at several scales reveal a higher level of intermittency in the mixed streams, which is related to the presence of well localized features. It is concluded that, apart from the differences in the nature of fluctuations in flows of different coronal origin, there is a small-scale structuring that depends on the origin of streams themselves but it is also related to a bursty generation of the fluctuations.

  1. THE SPECTROSCOPIC FOOTPRINT OF THE FAST SOLAR WIND

    SciTech Connect

    McIntosh, Scott W. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J. [ADNET Systems Inc., NASA Goddard Space Flight Center, Code 671.1, Greenbelt, MD 20771 (United States); De Pontieu, Bart, E-mail: mscott@ucar.edu, E-mail: robert.j.leamon@nasa.gov, E-mail: bdp@lmsal.com [Lockheed Martin Solar and Astrophysics Lab, 3251 Hanover Street, Org. ADBS, Building 252, Palo Alto, CA 94304 (United States)

    2011-01-20

    We analyze a large, complex equatorial coronal hole (ECH) and its immediate surroundings with a focus on the roots of the fast solar wind. We start by demonstrating that our ECH is indeed a source of the fast solar wind at 1 AU by examining in situ plasma measurements in conjunction with recently developed measures of magnetic conditions of the photosphere, inner heliosphere, and the mapping of the solar wind source region. We focus the bulk of our analysis on interpreting the thermal and spatial dependence of the non-thermal line widths in the ECH as measured by SOHO/SUMER by placing the measurements in context with recent studies of ubiquitous Alfven waves in the solar atmosphere and line profile asymmetries (indicative of episodic heating and mass loading of the coronal plasma) that originate in the strong, unipolar magnetic flux concentrations that comprise the supergranular network. The results presented in this paper are consistent with a picture where a significant portion of the energy responsible for the transport of heated mass into the fast solar wind is provided by episodically occurring small-scale events (likely driven by magnetic reconnection) in the upper chromosphere and transition region of the strong magnetic flux regions that comprise the supergranular network.

  2. Bow Shock in Interaction of Solar Wind with Cometary Coma

    NASA Astrophysics Data System (ADS)

    Losseva, T. V.; Gisko, A. A.; Popel, S. I.; Vladimirov, S. V.

    2003-05-01

    The process of interaction of Solar wind with cometary coma is considered. The description is performed on the basis of a self-consistent model which takes into account solar radiation; dust particle charging; evaporation and formation of neutral particles; photoionization; electric fields; the evolution of Solar wind ions, cometary ions and dust particles; as well as the dust charge variation. It is shown that the presence of dust in cometary coma can modify shock wave formed as a result of Solar wind interaction with a comet. The outer shock wave (bow shock) can be considered as an ion acoustic shock wave modified by dust particle charging process. Possible formation of dust structures in the region of the interaction of Solar wind with cometary coma is discussed. The developed model allows us to determine the shock front structure. For large enough dust densities (exceeding 106 cm-3 near the comet nucleus) at the region of bow shock front dust particles acquiring positive variable charges influence drastically the structure of the shock front. Its width is in accordance with the theory of dust ion acoustic shocks [1, 2]. The work is supported by the Russian Foundation for Basic Research (grants No. 02-02-17369, 03-02-16664). [1] S.I. Popel, M.Y. Yu, and V.N. Tsytovich, Phys. Plasmas 3, 4313 (1996). [2] S.I. Popel, A.A. Gisko, A.P. Golub', and T.V. Losseva et al. Phys. Plasmas 7, 2410 (2000).

  3. ACCELERATION OF THE SOLAR WIND BY ALFVEN WAVE PACKETS

    SciTech Connect

    Galinsky, V. L.; Shevchenko, V. I., E-mail: vit@ucsd.edu [ECE Department, UC San Diego, MC 407, La Jolla, CA 92093-0407 (United States)

    2013-01-20

    A scale separation kinetic model of the solar wind acceleration is presented. The model assumes an isotropic Maxwellian distribution of protons and a constant influx of outward propagating Alfven waves with a single exponent Kolmogorov-type spectrum at the base of a coronal acceleration region ({approx}2 R {sub Sun }). Our results indicate that nonlinear cyclotron resonant interaction taking energy from Alfven waves and depositing it into mostly perpendicular heating of protons in initially weakly expanding plasma in a spherically non-uniform magnetic field is able to produce the typical fast solar wind velocities for the typical plasma and wave conditions after expansion to about 5-10 solar radii R {sub Sun }. The acceleration model takes into account the gravity force and the ambipolar electric field, as well as the mirror force, which plays the most important role in driving the solar wind acceleration. Contrary to the recent claims of Isenberg, the cold plasma dispersion only slightly slows down the acceleration and actually helps in obtaining the more realistic fast solar wind speeds.

  4. Dual Nature of the Solar Wind Quasi-Invariant

    NASA Astrophysics Data System (ADS)

    Fainberg, J.; Osherovich, V. A.

    2001-12-01

    Since the beginning of the space age numerous attempts have been made to relate solar wind parameters such as magnetic field B, solar wind speed v, density ? and others to sunspot numbers (SSN) (see for example, Slavin et al. [1986] and King [1979]). Recently it has been demonstrated that the solar wind quasi-invariant (B2/8? )/(? v2/2) followed the yearly sunspot numbers with a correlation coefficient = 0.98 (Osherovich, Fainberg and Stone, [1999]) for 28 years. Similar results for the 10 year period of Pioneer-Venus Orbiter (Fainberg, Osherovich and Stone, 2001) confirmed the global nature of QI as a new heliospheric index of solar activity. For interplanetary clouds, QI increases by at least an order of magnitude because of the magnetic field enhancement and the depletion due to expansion. Thus, short term variations of QI (days, hours) allow detection and classification of geo-effective interplanetary disturbances such as magnetic clouds. While SSN cannot help in describing and forecasting individual geo-effective events, QI is suitable for such tasks. With data from Wind, Ulysses and other spacecraft, we will illustrate the application of QI in describing the level of long (years) and short term solar activity. References: Fainberg, J, V Osherovich and R G Stone, GRL, 28(8), 1447, 2001. King, J H, JGR, 84, 5938, 1979. Osherovich, V, J Fainberg and R G Stone, GRL, 26(16), 2597, 1999. Slavin, J A, G Jungman and E J Smith, GRL, 13, 6, 513, 1986.

  5. Anisotropic MHD Turbulence in the Interstellar Medium and Solar Wind A. Bhattacharjee and C. S. Ng

    E-print Network

    Ng, Chung-Sang

    Anisotropic MHD Turbulence in the Interstellar Medium and Solar Wind A. Bhattacharjee and C. S. Ng turbulence in the interstellar medium and the solar wind. The model is motivated by observations that show

  6. Radio interferometer observations of turbulence in the inner solar wind

    Microsoft Academic Search

    S. R. Spangler; T. Sakurai; W. A. Coles; R. R. Grall; J. K. Harmon

    1996-01-01

    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?n(q)=CN2q??, where

  7. Radio interferometer observations of turbulence in the inner solar wind

    Microsoft Academic Search

    S. R. Spangler; T. Sakurai; W. A. Coles; R. R. Grall; J. K. Harmon

    1996-01-01

    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 Pdeltan(q)=CN2q-alpha, where

  8. Exploring the Solar Wind and Coronal Mass Ejections

    NSDL National Science Digital Library

    This is an activity about the solar activity cycle. Learners will construct a graph to identify a pattern of the number of observed sunspots and the number of coronal mass ejections emitted by the Sun over a fifteen year time span. A graphing calculator is recommended, but not required, for this activity. This is the second activity in the Solar Storms and You: Exploring the Wind from the Sun educator guide.

  9. Radio interferometer observations of turbulence in the inner solar wind

    SciTech Connect

    Spangler, S. R.; Sakurai, T.; Coles, W. A.; Grall, R. R.; Harmon, J. K. [Department of Physics and Astronomy, University of Iowa, Iowa City (United States); E.C.E. Department, University of California at San Diego, La Jolla (United States); Arecibo Observatory, Arecibo (Puerto Rico)

    1996-07-20

    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}}{sub n}(q)=C{sub N}{sup 2}q{sup -{alpha}}, where q is the spatial wavenumber, these observations yield both {alpha} and the path-integrated value of C{sub N}{sup 2}. 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 16 sources observed at a wide range of solar elongations and at different times. These observations show that the coefficient C{sub N}{sup 2} depends on heliocentric distance as approximately C{sub N}{sup 2}{proportional_to}(R/R{sub {center_dot}}){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 Wentzel-Kramers-Brillouin (WKB)-type evolution of the turbulence with heliocentric distance.

  10. Dependence of Empirical Models of Solar Wind Coupling on Solar Cycle, Season, and Dynamic Pressure

    NASA Astrophysics Data System (ADS)

    McPherron, R. L.; Pulkkinen, T. I.; Baker, D. N.

    2010-12-01

    The coupling of the solar wind to the magnetosphere is examined empirically with linear prediction filters. Various proposed solar wind coupling functions are used as input and different magnetic indices are used as the output from the filter. Average filters are calculated for different times in the solar cycle, different months of the year, and different levels of solar wind dynamic pressure. Preliminary results indicate that there is no detectable seasonal variation in the VBs to AL filter, but there is a strong maximum in the VBs-AU filter centered on summer solstice. Both filters show a maximum in coupling in the declining phase of the solar cycle, and at the stream interface within a corotating interaction region, both times of high dynamic pressure. Filters calculated for different levels of dynamic pressure clearly show that the weakest coupling occurs for the highest pressure. We also show initial results for multi channel filters that self-consistently estimate both the reconnection and viscous contributions to coupling. Viscous coupling accounts for about 5% of the AL index while reconnection accounts for about 55%. The remaining variance in the index is uncorrelated with the solar wind and presumably a consequence of both internal processes and noise in the input and output data. State-dependent linear prediction filters provide a means to approximate the non-linear response of the magnetosphere to changes in the solar wind.

  11. Anisotropic winds from close-in extra-solar planets

    E-print Network

    James M. Stone; Daniel Proga

    2008-12-13

    We present two-dimensional hydrodynamic models of thermally driven winds from highly irradiated, close-in extra-solar planets. We adopt a very simple treatment of the radiative heating processes at the base of the wind, and instead focus on the differences between the properties of outflows in multidimensions in comparison to spherically symmetric models computed with the same methods. For hot (T > 2 x 10^{4} K) or highly ionized gas, we find strong (supersonic) polar flows are formed above the planet surface which produce weak shocks and outflow on the night-side. In comparison to a spherically symmetric wind with the same parameters, the sonic surface on the day-side is much closer to the planet surface in multidimensions, and the total mass loss rate is reduced by almost a factor of four. We also compute the steady-state structure of interacting planetary and stellar winds. Both winds end in a termination shock, with a parabolic contact discontinuity which is draped over the planet separating the two shocked winds. The planetary wind termination shock and the sonic surface in the wind are well separated, so that the mass loss rate from the planet is essentially unaffected. However, the confinement of the planetary wind to the small volume bounded by the contact discontinuity greatly enhances the column density close to the planet, which might be important for the interpretation of observations of absorption lines formed by gas surrounding transiting planets.

  12. The Eect of the Tilt of the HCS on the Solar Wind Speed in the Outer Heliosphere

    E-print Network

    Richardson, John

    1 The Eect of the Tilt of the HCS on the Solar Wind Speed in the Outer Heliosphere J. D. Richardson: THE HCS TILT AND THE SOLAR WIND SPEED #12;2 Abstract. The ow of solar wind from the Sun is bimodal. High with the HCS tilt controls the solar wind velocities in the outer heliosphere near solar minimum when the Sun

  13. Solar Wind Electron Proton Alpha Monitor (SWEPAM) for the Advanced Composition Explorer

    Microsoft Academic Search

    D. J. McComas; S. J. Bame; P. Barker; W. C. Feldman; J. L. Phillips; P. Riley; J. W. Griffee

    1998-01-01

    The Solar Wind Electron Proton Alpha Monitor (SWEPAM) experiment provides the bulk solar wind observations for the Advanced\\u000a Composition Explorer (ACE). These observations provide the context for elemental and isotopic composition measurements made\\u000a on ACE as well as allowing the direct examination of numerous solar wind phenomena such as coronal mass ejections, interplanetary\\u000a shocks, and solar wind fine structure, with

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  15. Electric Solar Wind Sail (E-sail) mission to asteroids

    NASA Astrophysics Data System (ADS)

    Merikallio, Sini; Janhunen, Pekka; Toivanen, Petri; Jouni Envall, M.(Tech.).

    2012-07-01

    There are an estimated one to two million asteroids of diameter over 1 km in-between the orbits of Mars and Jupiter. Impact threat, mining prospects and the understanding of solar system history make asteroids interesting objects for further in-situ studies. Electric Solar Wind Sail (E-sail) [1] technology enables touring several different asteroids with the same spacecraft. It is a propulsion technology first proposed in 2006 and currently developed with the EUs FP7 funding (http://www.electric-sailing.fi/fp7). The E-sail utilizes long, conducting, highly charged tethers to gather momentum from the solar wind ions. It does not consume any propellant and is well maneuverable. The Electric Solar Wind Sail producing 1 N of thrust at 1 AU distance from the Sun could be manufactured to weigh 100-150 kg in total. The constant acceleration gives a large advantage over traditional methods when calculated over the mission lifetime. In a ten year mission a baseline 1 N E-sail could produce 300 MNs of total impulse, Itot. As an example, such a total impulse would be able to move a 3 million ton Earth-threatening asteroid to a safer track [2]. With chemical propellant it would take 100 000 tons of fuel to achieve the same feat. Scientists and miners could have a closer look at several targets and they could decide the next target and the duration of investigations once at the vicinity of the asteroid, so the operations would be very flexible. Such a mission could characterize and map several asteroids, some with rapid fly-bys and a few chosen ones during lengthier rendezvous. [1] Janhunen, P., et. al, Electric solar wind sail: Towards test missions (Invited article), Rev. Sci. Instrum., 81, 111301, 2010. [2] Merikallio, S. and P. Janhunen, Moving an asteroid with electric solar wind sail, Astrophys. Space Sci. Trans., 6, 41-48, 2010

  16. XMM-Newton Observation of Solar Wind Charge Exchange Emission

    E-print Network

    S. L. Snowden; M. R. Collier; K. D. Kuntz

    2004-04-19

    We present an XMM-Newton spectrum of diffuse X-ray emission from within the solar system. The spectrum is dominated by probable C VI lines at 0.37 keV and 0.46 keV, an O VII line at 0.56 keV, O VIII lines at 0.65 keV and ~0.8 keV, Ne IX lines at ~0.92 keV, and Mg XI lines at ~1.35 keV. This spectrum is consistent with that expected from charge exchange emission between the highly ionized solar wind and either interstellar neutrals in the heliosphere or material from Earth's exosphere. The emission is clearly seen as a low-energy (E<1.5 keV) spectral enhancement in one of a series of four observations of the Hubble Deep Field North. The X-ray enhancement is concurrent with an enhancement in the solar wind measured by ACE, Wind, and SoHO spacecraft. The solar wind enhancement reaches a flux level an order of magnitude more intense than typical fluxes at 1 AU, and has a significantly enhanced O^{+7}/O^{+6} ratio. Besides being of interest in its own right for studies of the solar system, this emission can have significant consequences for observations of cosmological objects. It can provide emission lines at zero redshift which are of particular interest in studies of diffuse thermal emission (e.g., O VII and O VIII), and which can therefore act as contamination in the spectra of objects which cover the entire detector field of view. We propose the use of solar wind monitoring data as a diagnostic to screen for such possibilities.

  17. Enabling Technologies for High Penetration of Wind and Solar Energy

    SciTech Connect

    Denholm, P.

    2011-01-01

    High penetration of variable wind and solar electricity generation will require modifications to the electric power system. This work examines the impacts of variable generation, including uncertainty, ramp rate, ramp range, and potentially excess generation. Time-series simulations were performed in the Texas (ERCOT) grid where different mixes of wind, solar photovoltaic and concentrating solar power provide up to 80% of the electric demand. Different enabling technologies were examined, including conventional generator flexibility, demand response, load shifting, and energy storage. A variety of combinations of these technologies enabled low levels of surplus or curtailed wind and solar generation depending on the desired penetration of renewable sources. At lower levels of penetration (up to about 30% on an energy basis) increasing flexible generation, combined with demand response may be sufficient to accommodate variability and uncertainty. Introduction of load-shifting through real-time pricing or other market mechanisms further increases the penetration of variable generation. The limited time coincidence of wind and solar generation presents increasing challenges as these sources provide greater than 50% of total demand. System flexibility must be increased to the point of virtually eliminating must-run baseload generators during periods of high wind and solar generation. Energy storage also becomes increasingly important as lower cost flexibility options are exhausted. The study examines three classes of energy storage - electricity storage, including batteries and pumped hydro, hybrid storage (compressed-air energy storage), and thermal energy storage. Ignoring long-distance transmission options, a combination of load shifting and storage equal to about 12 hours of average demand may keep renewable energy curtailment below 10% in the simulated system.

  18. Development of the 3-D MHD model of the solar corona-solar wind combining system

    Microsoft Academic Search

    A. Nakamizo; T. Tanaka; Y. Kubo; S. Kamei; H. Shimazu; H. Shinagawa

    2009-01-01

    In the framework of integrated numerical space weather prediction, we have developed a 3-D MHD simulation model of the solar surface-solar wind system. We report the construction method of the model and its first results. By implementing a grid system with angularly unstructured and increasing radial spacing, we realized a spherical grid that has no pole singularity and realized a

  19. Centennial changes in the solar wind speed and in the open solar flux

    Microsoft Academic Search

    A. P. Rouillard; M. Lockwood; I. Finch

    2007-01-01

    We use combinations of geomagnetic indices, based on both variation range and hourly means, to derive the solar wind flow speed, the interplanetary magnetic field strength at 1 AU and the total open solar flux between 1895 and the present. We analyze the effects of the regression procedure and geomagnetic indices used by adopting four analysis methods. These give a

  20. Solar flares and solar wind helium enrichments: July 1965–July 1967

    Microsoft Academic Search

    J. Hirshberg; S. J. Bame; D. E. Robbins

    1972-01-01

    It has previously been suggested that the very high relative abundances of helium occasionally observed in the solar wind mark the plasma accelerated by major solar flares. To confirm this hypothesis, we have studied the 43 spectra with He\\/H ? 15% that were observed among 10300 spectra collected by Vela 3 between July 1965–July 1967. The 43 spectra were distributed

  1. Generalized similarity in magnetohydrodynamic turbulence as seen in the solar corona and solar wind

    Microsoft Academic Search

    S. C. Chapman; E. Leonardis; R. M. Nicol; C. Foullon

    2010-01-01

    A key property of turbulence is that it can be characterized and quantified in a robust and reproducible way in terms of the ensemble averaged statistical properties of fluctuations. Importantly, fluctuations associated with a turbulent field show similarity or scaling in their statistics and we test for this in observations of magnetohydrodynamic turbulence in the solar corona and solar wind

  2. THE SOLAR WIND INTERACTION WITH UNMAGNETIZED PLANETS: A TUTORIAL J. G. Luhmann

    E-print Network

    California at Berkeley, University of

    THE SOLAR WIND INTERACTION WITH UNMAGNETIZED PLANETS: A TUTORIAL J. G. Luhmann Institute of solar wind origin is transported through the ionopause and distributed within the ionosphere theorists and observationalists. The relative strength of the solar wind and ionospheric pressures at Mars

  3. Kolmogorov versus IroshnikovKraichnan spectra: Consequences for ion heating in the solar wind

    E-print Network

    Ng, Chung-Sang

    heating in the solar wind C. S. Ng,1 A. Bhattacharjee,2 D. Munsi,2 P. A. Isenberg,2 and C. W. Smith2. Recently, a solar wind heating model based on Kolmogorov spectral scaling has produced reasonably good), Kolmogorov versus Iroshnikov Kraichnan spectra: Consequences for ion heating in the solar wind, J. Geophys

  4. Energetic plasma sheet electrons and their relationship with the solar wind: A Cluster and Geotail study

    E-print Network

    Li, Xinlin

    Energetic plasma sheet electrons and their relationship with the solar wind: A Cluster and Geotail and the solar wind, as well as >2 MeV geosynchronous electrons, is investigated using plasma sheet measurements from Cluster (2001­2005) and Geotail (1998­2005) and concurrent solar wind measurements from ACE

  5. THE GENESIS SOLAR-WIND COLLECTOR MATERIALS A. J. G. Jurewicz1

    E-print Network

    THE GENESIS SOLAR-WIND COLLECTOR MATERIALS A. J. G. Jurewicz1 , D. S. Burnett2 , R. C. Wiens3 , T. #12;THE GENESIS SOLAR-WIND COLLECTOR MATERIALS Abstract. Genesis (NASA Discovery Mission #5 to maximize the area for solar-wind collection. Most of the collection area consists of hexagonal collectors

  6. Enhanced solar wind geoeffectiveness after a sudden increase in dynamic pressure during southward IMF orientation

    E-print Network

    Lummerzheim, Dirk

    Enhanced solar wind geoeffectiveness after a sudden increase in dynamic pressure during southward increase in solar wind pressure results in poleward expansion of the auroral oval and closing of the polar show that southward IMF conditions combined with high solar wind dynamic pressure immediately after

  7. Gap filling of solar wind data by singular spectrum analysis D. Kondrashov,1

    E-print Network

    Ghil, Michael

    Gap filling of solar wind data by singular spectrum analysis D. Kondrashov,1 Y. Shprits,1 and M field are crucial for many space weather applications, and require timecontinuous solar wind in solar wind and IMF data, by com- bining it with geomagnetic indices that are timecontinuous

  8. J. Astrophys. Astr. (2006) 27, 17 Enigmatic Solar Wind Disappearance Events Do We Understand

    E-print Network

    Padmanabhan, Janardhan

    2006-01-01

    J. Astrophys. Astr. (2006) 27, 1­7 Enigmatic Solar Wind Disappearance Events ­ Do We Understand@prl.ernet.in Abstract. At the Sun­Earth distance of one astronomical unit (1 AU), the solar wind is known to be strongly, solar wind densities (average 10 cm-3 ) and velocities (average 450 km s-1 ) at 1 AU, are known

  9. Source regions of solar wind disappearance events P. Janardhan,1,3

    E-print Network

    Padmanabhan, Janardhan

    Source regions of solar wind disappearance events P. Janardhan,1,3 K. Fujiki,2 H. S. Sawant,3 M, in May 1999, March 2002, and May 2002, respectively, when the solar wind densities at 1 AU dropped-density anomalies observed at 1 AU are referred to as ``solar wind disappearance events'' and in this paper, we

  10. The orientation of plasma structure in the solar wind J. D. Richardson and K. I. Paularena

    E-print Network

    Richardson, John

    The orientation of plasma structure in the solar wind J. D. Richardson and K. I. Paularena Center, and WIND spacecraft are used to #12;nd the average east-west orientation of plasma structures in the solar correlations between data sets. These lags, when combined with the spacecraft positions and solar wind speeds

  11. A TRANSONIC COLLISIONLESS MODEL OF THE SOLAR WIND I. Zouganelis,1

    E-print Network

    Meyer-Vernet, Nicole

    A TRANSONIC COLLISIONLESS MODEL OF THE SOLAR WIND I. Zouganelis,1 M. Maksimovic,1 N. Meyer-Vernet,1 of the semicollisional nature of the solar wind, the collisionless or exospheric approach and the hydrodynamic one basic mechanisms of solar wind acceleration. Previous exospheric models have been able to re- produce

  12. Imaging the global solar wind flow in EUV Mike Gruntman,1

    E-print Network

    Gruntman, Mike

    Imaging the global solar wind flow in EUV Mike Gruntman,1 Vlad Izmodenov,2,3 and Vic Pizzo4] We advance the original concept of imaging the three-dimensional solar wind flow (Gruntman, 2001a) by characterizing expected heliospheric EUV signatures under assumptions of a realistic solar wind. Charge exchange

  13. The Solar Wind: Probing the Heliosphere with Multiple Spacecraft John D. Richardson

    E-print Network

    Richardson, John

    1 The Solar Wind: Probing the Heliosphere with Multiple Spacecraft John D. Richardson Center of the Voyager spacecraft in the outer heliosphere, Ulysses at high latitudes, and multiple solar wind monitors near Earth provides a unique opportunity to study the global structure and evolution of the solar wind

  14. Impact of the solar wind dynamic pressure on the Region 2 field-aligned currents

    E-print Network

    Higuchi, Tomoyuki

    Impact of the solar wind dynamic pressure on the Region 2 field-aligned currents S. Nakano,1,2 G and the solar wind dynamic pressure is investigated using magnetic field data from Defense Meteorological in the magnetosphere varies with the solar wind dynamic pressure. Therefore, we can expect that the Region 2 currents

  15. A SURVEY OF FIELD-ALIGNED MACH NUMBER AND PLASMA BETA IN THE SOLAR WIND

    E-print Network

    De Sterck, Hans

    A SURVEY OF FIELD-ALIGNED MACH NUMBER AND PLASMA BETA IN THE SOLAR WIND JOHAN DE KEYSER and MICHEL Katholieke Universiteit Leuven, Leuven, Belgium Abstract. We have surveyed solar wind plasma beta and field frequency of `magnet- ically dominated' solar wind, whose interaction with a planetary magnetosphere may

  16. Effect of solar wind pressure pulses on the size and strength of the auroral oval

    E-print Network

    Lummerzheim, Dirk

    Effect of solar wind pressure pulses on the size and strength of the auroral oval A. Boudouridis, E. [1] It has recently been found that solar wind dynamic pressure changes can dramatically affect solar wind dynamic pressure increases on the location, size, and intensity of the auroral oval using

  17. The structure and origin of magnetic clouds in the solar wind V. Bothmer1

    E-print Network

    Boyer, Edmond

    The structure and origin of magnetic clouds in the solar wind V. Bothmer1 * and R. Schwenn2 1 Space in the surrounding solar wind. Minimum variance analysis (MVA) showed that MCs can best be described as large- scale to be proportional to RÀ2X4 , thus being stronger compared to the average solar wind. Four dierent magnetic con

  18. Prediction of the AL index using solar wind Xinlin Li,1,2,5

    E-print Network

    Li, Xinlin

    Prediction of the AL index using solar wind parameters Xinlin Li,1,2,5 Kap Soo Oh,1,3 and M are based on solar wind and magnetometer data from the year 1995. The simple model predicts the 10-min averaged AL index for 1995 using only solar wind measurements with a prediction efficiency of 0

  19. Discrepancies in the Prediction of Solar Wind using Potential Field Source Surface Model: An

    E-print Network

    Zhao, Xuepu

    Discrepancies in the Prediction of Solar Wind using Potential Field Source Surface Model between the magnetic flux tube expansion factor (FTE) at the source surface and the solar wind speed observed at Earth, which has been made use of in the prediction of solar wind speed near the Earth

  20. Interaction of a nonuniform solar wind with the local interstellar medium

    Microsoft Academic Search

    H. L. Pauls; G. P. Zank

    1996-01-01

    Results from a fully time dependent three-dimensionM gasdynamic model of the interaction of the solar wind with the local interstellar medium are presented. Both subsonic and supersonic interstellar winds are considered, while the mediating effects of interstellar neutrals, magnetic fields, and cosmic rays are ignored. In accord with solar minimum observations by Ulysses, the solar wind properties are assumed to

  1. Interaction of a nonuniform solar wind with the local interstellar medium

    Microsoft Academic Search

    H. L. Pauls; G. P. Zank

    1996-01-01

    Results from a fully time dependent three-dimensional gasdynamic model of the interaction of the solar wind with the local interstellar medium are presented. Both subsonic and supersonic interstellar winds are considered, while the mediating effects of interstellar neutrals, magnetic fields, and cosmic rays are ignored. In accord with solar minimum observations by Ulysses, the solar wind properties are assumed to

  2. Three dimensional structure of correlations between intensity variation of cosmic rays and solar wind velocity

    Microsoft Academic Search

    H. Kojima; T. Fujii; Y. Hayashi; S. Kawakami; M. Minamino; H. Miyauchi; T. Nonaka; S. Ogio; H. Tanaka; E. Usui; Y. Yamashita; A. Oshima; H. M. Antia; S. R. Dugad; U. D. Goswami; S. K. Gupta; P. K. Mohanty; P. K. Nayak; P. Subramanian; S. C. Tonwar; S. Shibata; I. Morishita

    A three dimensional structure of a solar wind effect on the intensity variation of cosmic rays has been investigated by using the regression analysis method in this paper. The solar wind effect discussed here is represented by the regression coefficients between the intensity variation of cosmic rays and the solar wind velocity. The data of cosmic ray intensity used in

  3. Resonant and adiabatic heating and acceleration of ions in the fast solar wind

    Microsoft Academic Search

    V. I. Shevchenko; V. I. Galinsky; M. V. Medvedev; P. H. Diamond; S. K. Ride; R. Z. Sagdeev

    1998-01-01

    It is well known from solar wind observations that speed and temperature of various species of the fast solar wind exhibit several important features. First of all, the temperature of the solar wind ions is anisotropic, with the perpendicular component exceeding the parallel one. Second, the heavier species are preferentially accelerated and heated. Several attempts of explaining these features on

  4. Solar Wind and Interplanetary Magnetic Field: A Tutorial C. T. Russell

    E-print Network

    Russell, Christopher T.

    Solar Wind and Interplanetary Magnetic Field: A Tutorial C. T. Russell Institute of Geophysics at the center of the sun to its radiation into space by the photosphere, but most importantly for the solar wind controls the properties of the solar wind. In this tutorial review we examine the properties of the fields

  5. Radial evolution of micro-turbulence in the solar wind observed with interplanetary scintillation

    Microsoft Academic Search

    Yohei Yamauchi; Munetoshi Tokumaru; Masayoshi Kojima; P. K. Manoharan; Ruth Esser

    1999-01-01

    It is well known that the solar wind is a magneto-hydrodynamic (MHD) turbulent flow. The MHD turbulence is considered to play an important role in energy transport and acceleration processes in the solar wind (see (1)). Some acceleration models in which the solar wind is primarily driven by the turbulence process caused by the damping of MHD waves have been

  6. Response of the midtail electric field to enhanced solar wind energy input

    Microsoft Academic Search

    R. Nakamura; L. F. Bargatze; T. Mukai; T. Nagai; K. B. Baker; M. R. Hairston; P. H. Reiff; A. A. Petrukovich; M. Nozdrachev; O. A. Troshichev

    1999-01-01

    We study the response of midtail plasma and field parameters to enhanced solar wind electric field input for two substorm intervals on November 22, 1995. The solar wind input signatures were quite different for these two substorms, which had major Pi2 onsets at 1108 and 1502 UT. The solar wind input for the 1108 UT substorm had a short timescale

  7. The radial temperature profile of the solar wind John D. Richardson

    E-print Network

    Richardson, John

    is the Alfve`n speed and V is the solar wind speed. Only about 4% of the available energy from this sourceThe radial temperature profile of the solar wind John D. Richardson Center for Space Research but do not account for the smaller scale (few AU) temperature variations. At 1 AU, the solar wind

  8. Multiple-spacecraft study of an extended magnetic structure in the solar wind

    E-print Network

    Wiegelmann, Thomas

    ] Flux ropes have been observed in the solar wind by Moldwin et al. [1995, 2000], and they suggested to study magnetic structures in the solar wind. Their advantage, compared to single-spacecraft observations that these flux ropes might be generated locally in the solar wind. Basic characteristics, such as the length

  9. Solar wind control of Pc5 pulsation power at geosynchronous orbit

    Microsoft Academic Search

    Kazue Takahashi; Aleksandr Y. Ukhorskiy

    2007-01-01

    We statistically study the solar wind control of Pc5 magnetic pulsations at geosynchronous orbit. Solar wind conditions are quantified with the use of proton measurements at L1 from the ACE spacecraft that are propagated to the bow shock nose. In addition to the solar wind velocity, Vsw, density, Nsw, and dynamic pressure, Psw, we also consider the dynamic pressure variance

  10. Radial evolution of the electron distribution functions in the fast solar wind between 0.3

    E-print Network

    California at Berkeley, University of

    Radial evolution of the electron distribution functions in the fast solar wind between 0.3 and 1., et al. (2005), Radial evolution of the electron distribution functions in the fast solar wind between distribution functions in the fast solar wind between 0.3 and 1.5 AU. For this purpose we combine data measured

  11. Modeling the young Sun's solar wind and its interaction with Earth's paleomagnetosphere

    Microsoft Academic Search

    M. Glenn Sterenborg; O. Cohen; J. J. Drake; T. I. Gombosi

    2011-01-01

    We present a focused parameter study of solar wind–magnetosphere interaction for the young Sun and Earth, ?3.5 Gyr ago, that relies on magnetohydrodynamic (MHD) simulations for both the solar wind and the magnetosphere. By simulating the quiescent young Sun and its wind we are able to propagate the MHD simulations up to Earth's magnetosphere and obtain a physically realistic solar

  12. Modeling the young Sun's solar wind and its interaction with Earth's paleomagnetosphere

    Microsoft Academic Search

    M. Glenn Sterenborg; Ofer Cohen; Jeremy J. Drake; Tamas I. Gombosi

    2011-01-01

    We present a focused parameter study of solar wind-magnetosphere interaction for the young Sun and Earth, ˜3.5 Gyr ago, that relies on magnetohydrodynamic (MHD) simulations for both the solar wind and the magnetosphere. By simulating the quiescent young Sun and its wind we are able to propagate the MHD simulations up to Earth's magnetosphere and obtain a physically realistic solar

  13. SWERA - SOLAR AND WIND ENERGY RESOURCE ASSESSMENT - REGIONAL AGENCY FOR LATIN AMERICA

    Microsoft Academic Search

    Enio Bueno Pereira; Fernando R. Martins; Silvia V. Pereira; Sergio Colle; Samuel L. Abreu; Alfredo Curbelo Alonso; Tom Hamlin

    SWERA - Solar and Wind Energy Resource Assessment is a project financed by UNEP, with co-financing by GEF, in the area of renewable energies, and more specifically solar and wind energy. The project includes the efforts of several countries, but is primarily directed to developing countries. The project will bring together high quality information on solar and wind energy resources

  14. Solar Wind Variations Related to Fluctuations of the North Atlantic Oscillation

    Microsoft Academic Search

    Fredrik Boberg; Henrik Lundstedt

    2002-01-01

    A study on a possible solar wind interaction with the North Atlantic Oscillation (NAO) is performed. Results are presented suggesting a relationship between the NAO index and the electric field strength E of the solar wind. A possible scenario for the suggested interaction is that an electromagnetic disturbance is generated by the solar wind in the global electric circuit of

  15. Optimal design and techno-economic analysis of a hybrid solar–wind power generation system

    Microsoft Academic Search

    Hongxing Yang; Zhou Wei; Lou Chengzhi

    2009-01-01

    Solar energy and wind energy are the two most viable renewable energy resources in the world. Good compensation characters are usually found between solar energy and wind energy. This paper recommend an optimal design model for designing hybrid solar–wind systems employing battery banks for calculating the system optimum configurations and ensuring that the annualized cost of the systems is minimized

  16. Feasibility of hybrid (wind + solar) power systems for Dhahran, Saudi Arabia

    Microsoft Academic Search

    M. A. Elhadidy; S. M. Shaahid

    1999-01-01

    Hourly mean wind-speed and solar radiation data for the period 1986–1993 [except the years 1989 (some data is missing) and 1991 (Gulf War)] recorded at the solar radiation and meteorological monitoring station, Dhahran (26° 32? N, 50° 13? E), Saudi Arabia, have been analyzed to report the monthly variation of wind speed and solar radiation, probability distribution of wind speed

  17. Direct evidence for magnetic reconnection in the solar wind near 1 AU

    Microsoft Academic Search

    J. T. Gosling; R. M. Skoug; D. J. McComas; C. W. Smith

    2005-01-01

    We have obtained direct evidence for local magnetic reconnection in the solar wind using solar wind plasma and magnetic field data obtained by the Advanced Composition Explorer (ACE). The prime evidence consists of accelerated ion flow observed within magnetic field reversal regions in the solar wind. Here we report such observations obtained in the interior of an interplanetary coronal mass

  18. Weaker solar wind from the polar coronal holes and the whole Sun

    Microsoft Academic Search

    D. J. McComas; R. W. Ebert; H. A. Elliott; B. E. Goldstein; J. T. Gosling; N. A. Schwadron; R. M. Skoug

    2008-01-01

    Observations of solar wind from both large polar coronal holes (PCHs) during Ulysses' third orbit showed that the fast solar wind was slightly slower, significantly less dense, cooler, and had less mass and momentum flux than during the previous solar minimum (first) orbit. In addition, while much more variable, measurements in the slower, in-ecliptic wind match quantitatively with Ulysses and

  19. Modeling of a solar eruption and its relations with a solar wind

    NASA Astrophysics Data System (ADS)

    Lee, H.; Magara, T.; Kang, J.

    2014-12-01

    We investigate how a solar eruption is related to a solar wind which continuously exists during a pre-eruptive phase to form a helmet streamer on the Sun. To understand a mechanism of a solar eruption, we perform three-dimensional simulations based on zero-beta magnetohydrodyamic (MHD) equations. The pre-eruptive magnetic configuration in the simulations is given via nonlinear force-free field approximation applied to either a flux emergence simulation data or SDO/HMI data. On the basis of a simulation result, we discuss a dynamic relationship between a solar eruption and a solar wind, the latter of which may be a possible driver of a solar eruption.

  20. Physical nature of the low-speed solar wind

    SciTech Connect

    Gosling, J.T.

    1996-09-01

    In situ observations indicate that the low-speed wind is highly variable. It commonly originates on open field lines that thread coronal streamers in the vicinity of the magnetic equator, but transient ejections are also a source of low-speed flows on occasion. Close to the Sun a large flow shear probably is common at the interface between low- and high-speed flows. Near solar activity minimum low-speed flows are confined to a narrow band 40-45{degree} wide centered roughly on the solar equator, but near solar maximum low-speed flows may dominate at all heliographic latitudes.

  1. The genesis solar-wind sample return mission

    SciTech Connect

    Wiens, Roger C [Los Alamos National Laboratory

    2009-01-01

    The compositions of the Earth's crust and mantle, and those of the Moon and Mars, are relatively well known both isotopically and elementally. The same is true of our knowledge of the asteroid belt composition, based on meteorite analyses. Remote measurements of Venus, the Jovian atmosphere, and the outer planet moons, have provided some estimates of their compositions. The Sun constitutes a large majority, > 99%, of all the matter in the solar system. The elemental composition of the photosphere, the visible 'surface' of the Sun, is constrained by absorption lines produced by particles above the surface. Abundances for many elements are reported to the {+-}10 or 20% accuracy level. However, the abundances of other important elements, such as neon, cannot be determined in this way due to a relative lack of atomic states at low excitation energies. Additionally and most importantly, the isotopic composition of the Sun cannot be determined astronomically except for a few species which form molecules above sunspots, and estimates derived from these sources lack the accuracy desired for comparison with meteoritic and planetary surface samples measured on the Earth. The solar wind spreads a sample of solar particles throughout the heliosphere, though the sample is very rarified: collecting a nanogram of oxygen, the third most abundant element, in a square centimeter cross section at the Earth's distance from the Sun takes five years. Nevertheless, foil collectors exposed to the solar wind for periods of hours on the surface of the Moon during the Apollo missions were used to determine the helium and neon solar-wind compositions sufficiently to show that the Earth's atmospheric neon was significantly evolved relative to the Sun. Spacecraft instruments developed subsequently have provided many insights into the composition of the solar wind, mostly in terms of elemental composition. These instruments have the advantage of observing a number of parameters simultaneously, including charge state distributions, velocities, and densities, all of which have been instrumental in characterizing the nature of the solar wind. However, these instruments have lacked the ability to make large dynamic range measurements of adjacent isotopes (i.e., {sup 17}O/{sup 16}O {approx} 2500) or provide the permil (tenths of percent) accuracy desirable for comparison with geochemical isotopic measurements. An accurate knowledge of the solar and solar-wind compositions helps to answer important questions across a number of disciplines. It aids in understanding the acceleration mechanisms of the solar wind, gives an improved picture of the charged particle environment near the photosphere, it constrains processes within the Sun over its history, and it provides a database by which to compare differences among planetary systems with the solar system's starting composition, providing key information on planetary evolution. For example, precise knowledge of solar isotopic and elemental compositions of volatile species in the Sun provides a baseline for models of atmospheric evolution over time for Earth, Venus, and Mars. Additionally, volatile and chemically active elements such as C, H, O, N, and S can tell us about processes active during the evolution of the solar nebula. A classic example of this is the oxygen isotope system. In the 1970s it was determined that the oxygen isotopic ratio in refractory inclusions in primitive meteorites was enriched {approx}4% in {sup 16}O relative to the average terrestrial, lunar, and thermally processed meteorite materials. In addition, all processed solar-system materials appeared to each have a unique oxygen isotopic composition (except the Moon and Earth, which are thought to be formed from the same materials), though differences are in the fraction of a percent range, much smaller than the refractory material {sup 16}O enrichment. Several theories were developed over the years to account for the oxygen isotope heterogeneity, each theory predicting a different solar isotopic composition and each invoking a differ

  2. Assessment of existing studies of wind loading on solar collectors

    SciTech Connect

    Murphy, L. M.

    1981-02-01

    In developing solar collectors, wind loading is the major structural design consideration. Wind loading investigations have focused on establishing safe bounds for steady state loading and verifying rational but initial and conservative design approaches for the various solar collector concepts. As such, the effort has been very successful, and has contributed greatly to both the recognition and qualitative understanding of many of the physical phenomena involved. Loading coefficients corresponding to mean wind velocities have been derived in these prior studies to measure the expected structural loading on the various solar collectors. Current design and testing procedures for wind loading are discussed. The test results corresponding to numerous wind tests on heliostats, parabolic troughs, parabolic dishes, and field mounted photovoltaic arrays are discussed and the applicability of the findings across the various technologies is assessed. One of the most significant consistencies in the data from all the technologies is the apparent benefit provided by fences and field shielding. Taken in toto, these data show that load reductions of three or possibly more seem feasible, though a more thorough understanding of the phenomena involved must be attained before this benefit can be realized. It is recommended that the required understanding be developed to take advantage of this benefit and that field tests be conducted to correlate with both analyses and tests.

  3. Solar wind turbulence at 0.72 AU and solar minimum

    E-print Network

    Teodorescu, Eliza; Munteanu, Costel; Zhang, Tielong; Bruno, Roberto; Kovacs, Peter

    2015-01-01

    We investigate Venus Express (VEX) observations of magnetic field fluctuations performed systematically in the solar wind at 0.72 Astronomical Units (AU), between 2007 and 2009, during the deep minimum of the solar cycle 24. The Power Spectral Densities (PSD) of the magnetic field components have been computed for the time intervals that satisfy data integrity criteria and have been grouped according to the type of wind, fast and slow defined for speeds larger and respectively smaller than 450 km/s. The PSDs show higher levels of power for the fast than for the slow wind. The spectral slopes estimated for all PSDs in the frequency range 0.005-0.1 Hz exhibit a normal distribution. The average value of the trace of the spectral matrix is -1.60 for fast solar wind and -1.65 for slow wind. Compared to the corresponding average slopes at 1 AU, the PSDs are shallower at 0.72 AU for slow wind conditions suggesting a steepening of the solar wind spectra between Venus and Earth. No significant time variation trend is ...

  4. Iron charge states observed in the solar wind

    NASA Technical Reports Server (NTRS)

    Ipavich, F. M.; Galvin, A. B.; Gloeckler, G.; Hovestadt, D.; Klecker, B.; Scholer, M.

    1983-01-01

    Solar wind measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE-3 are reported. The low energy section of approx the ULECA sensor selects particles by their energy per charge (over the range 3.6 keV/Q to 30 keV/Q) and simultaneously measures their total energy with two low-noise solid state detectors. Solar wind Fe charge state measurements from three time periods of high speed solar wind occurring during a post-shock flow and a coronal hole-associated high speed stream are presented. Analysis of the post-shock flow solar wind indicates the charge state distributions for Fe were peaked at approx +16, indicative of an unusually high coronal temperature (3,000,000 K). In contrast, the Fe charge state distribution observed in a coronal hole-associated high speed stream peaks at approx -9, indicating a much lower coronal temperature (1,400,000 K). This constitutes the first reported measurements of iron charge states in a coronal hole-associated high speed stream.

  5. Genesis Solar-Wind Sample Return Mission: The Materials

    NASA Technical Reports Server (NTRS)

    Jurewicz, A. J. G.; Burnett, D. S.; Wiens, R. C.; Woolum, D.

    2003-01-01

    The Genesis spacecraft has two primary instruments which passively collect solar wind. The first is the collector arrays , a set of panels, each of which can deploy separately to sample the different kinds of solar wind (regimes). The second is the concentrator, an electrostatic mirror which will concentrate ions of mass 4 through mass 25 by about a factor of 20 by focusing them onto a 6 cm diameter target. When not deployed, these instruments fit into a compact canister. After a two year exposure time, the deployed instruments can be folded up, sealed into the canister, and returned to earth for laboratory analysis. Both the collector arrays and the concentrator will contain suites of ultra-high purity target materials, each of which is tailored to enable the analysis of a different family of elements. This abstract is meant to give a brief overview of the Genesis mission, insight into what materials were chosen for flight and why, as well as head s up information as to what will be available to planetary scientist for analysis when the solar-wind samples return to Earth in 2003. Earth. The elemental and isotopic abundances of the solar wind will be analyzed in state-of-the-art laboratories, and a portion of the sample will be archived for the use of future generations of planetary scientists. Technical information about the mission can be found at www.gps.caltech.edu/genesis.

  6. Shape of the Geomagnetic Field Solar Wind Boundary

    Microsoft Academic Search

    Gilbert D. Mead; David B. Beard

    1964-01-01

    The shape of the boundary of the geomagnetic field in a solar wind has been calculated by a self-consistent method in which, in first order, approximate magnetic fields are used to calculate a boundary surface. The electric currents in this boundary produce mag- netic fields, which can be calculated once the first surface is known. These are added to the

  7. The Solar Wind in the Outer Heliosphere and Heliosheath

    NASA Technical Reports Server (NTRS)

    Richardson, J. D.; Burlaga, L. F.

    2011-01-01

    The solar wind environment has a large influence on the transport of cosmic rays. This chapter discusses the observations of the solar wind plasma and magnetic field in the outer heliosphere and the heliosheath. In the supersonic solar wind, interaction regions with large magnetic fields form barriers to cosmic ray transport. This effect, the "CR-B" relationship, has been quantified and is shown to be valid everywhere inside the termination shock (TS). In the heliosheath, this relationship breaks down, perhaps because of a change in the nature of the turbulence. Turbulence is compressive in the heliosheath, whereas it was non-compressive in the solar wind. The plasma pressure in the outer heliosphere is dominated by the pickup ions which gain most of the flow energy at the TS. The heliosheath plasma and magnetic field are highly variable on scales as small as ten minutes. The plasma flow turns away from the nose roughly as predicted, but the radial speeds at Voyager 1 are much less than those at Voyager 2, which is not understood. Despite predictions to the contrary, magnetic reconnection is not an important process in the inner heliosheath with only one observed occurrence to date.

  8. The source of electrostatic fluctuations in the solar-wind

    NASA Technical Reports Server (NTRS)

    Lemons, D. S.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Gary, S. P.; Gosling, J. T.

    1979-01-01

    Solar wind electron and ion distribution functions measured simultaneously with or close to times of intense electrostatic fluctuations are subjected to a linear Vlasov stability analysis. Although all distributions tested were found to be stable, the analysis suggests that the ion beam instability is the most likely source of the fluctuations.

  9. The solar wind-magnetosphere interaction on Mercury

    Microsoft Academic Search

    R. Killen; M. Sarantos

    2006-01-01

    We have modeled the supply of ions to the Hermean surface in response to the solar wind and interplanetary magnetic field (IMF), including the transport and loss of magnetospheric ions. Of particular interest to this study will be six CME events detected by the Helios spacecraft within Mercury's orbital range. Previously published modeling runs have tested exploratory or extreme cases

  10. Alfvénic Turbulence and the Acceleration of the Fast Solar Wind

    Microsoft Academic Search

    A. Verdini; M. Velli; E. Buchlin

    2008-01-01

    Alfvenic turbulence is usually invoked and used in many solar wind models (Isenberg & Hollweg 1982, Tu et al. 1984, Hu et al. 2000, Li 2003, Isenberg 2004) as a process responsible for the transfer of energy released at large scales in the photosphere towards small scales in the corona, where it is dissipated. Usually an initial spectrum is prescribed

  11. Self-consistent model of solar wind electrons

    Microsoft Academic Search

    V. Pierrard; M. Maksimovic; J. Lemaire

    2001-01-01

    We model the transformation of the steady state electron velocity distribution function in the collisional transition region of the solar wind by solving the Fokker-Planck equation. Alongside the proton and electron Coulomb collisions, effects of gravitational and electric and magnetic forces are also considered. The Coulomb collision term is calculated for any background velocity distribution function using a spectral method

  12. The Solar Wind Interaction with Mars (SWIM) Model Challenge

    Microsoft Academic Search

    David Brain

    2008-01-01

    The number, variety, and complexity of global models of the Martian solar wind interaction have increased greatly in recent years. These simulations employ physical assumptions ranging from MHD to hybrid, and have been applied to investigate a variety of processes and features of the Martian system, including the global shapes of plasma boundaries, magnetic field structure and topology, ionospheric structure,

  13. Energy coupling between the solar wind and the magnetosphere

    Microsoft Academic Search

    S.-I. Akasofu

    1981-01-01

    This paper describes in detail how we are led to the first approximation expression for the solar wind-magnetosphere energy coupling function ?, which correlates well with the total energy consumption rate UTof the magnetosphere. It is shown that ? is the primary factor which controls the time development of magnetospheric substorms and storms. The finding of this particular expression ?

  14. Depletion of solar wind plasma near a planetary boundary

    Microsoft Academic Search

    B. J. Zwan; R. A. Wolf

    1976-01-01

    A mathematical model is presented that describes the squeezing of solar wind plasma out along interplanetary magnetic field lines in the region between the bow shock and the effective planetary boundary (in the case of the earth, the magnetopause). In the absence of local magnetic merging the squeezing process should create a 'depletion layer,' a region of very low plasma

  15. The solar wind-magnetosphere energy coupling and magnetospheric disturbances

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1980-01-01

    Energy coupling between the solar wind and the magnetosphere is examined and the influence of this coupling on magnetospheric disturbances is discussed. Following a review of the components of the total energy production rate of the magnetosphere and progress in the study of solar wind-magnetosphere correlations, the derivation of the solar wind-magnetosphere energy coupling function, which has been found to correlate well with the total magnetospheric energy production rate, is presented. Examination of the relations between the energy coupling function and the type of magnetic disturbance with which it is associated indicates that magnetic storms with a large sudden storm commencement and a weak main phase are associated with small energy coupling, while values of the coupling function greater than 5 x 10 to the 18th to 10 to the 19th erg/sec are required for the development of a major geomagnetic storm. The magnetospheric substorm is shown to be a direct result of increased solar wind-magnetosphere energy coupling rather than the sudden conversion of stored magnetic energy. Finally, it is indicated that at energy couplings greater than 10 to the 19th erg/sec, the positive feedback process responsible for substorms breaks down, resulting in the abnormal growth of the ring current.

  16. A space motor using solar wind energy (magnetic particle sail)

    Microsoft Academic Search

    A. A. Bolonkin

    1992-01-01

    A space motor that uses solar wind for spacecraft thrust and electric energy production is described. Since the particle flow density is not great, protons and electrons are collected with a powerful magnet and their consequential reflection, absorption, or acceleration are used to create thrust. If used in conjuction with a superconductor circuit the motor can reach a thrust of

  17. On the geomagnetic effects of solar wind interplanetary magnetic structures

    Microsoft Academic Search

    E. Echer; W. D. Gonzalez; M. V. Alves

    2006-01-01

    We present in this work a statistical study of the geoeffectiveness of the solar wind magnetic interplanetary structures over the entire observational period (1964–2003). The structures studied were magnetic clouds (MCs, 170 events), corotating interaction regions (CIRs, 727 events) and interplanetary shocks (830 events). The geoeffectiveness was assessed in terms of the geomagnetic index Kp, AE, and Dst peak values

  18. Wind loss prevention for open cavity solar receivers

    Microsoft Academic Search

    T. J. Nussdorfer; D. H. Ross

    1982-01-01

    Apparatus for minimizing thermal loss in a windowless, open cavity solar receiver due to airflow at the receiver aperture includes means for deflecting wind away from the cavity opening such that flow stream reattachment occurs away from the receiver aperture to provide a dead air zone at the cavity opening. This prevents turbulent-mixing airflow exchange between ambient air and heated

  19. The Solar-Wind Interaction with Comet Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Burch, James

    2015-04-01

    The instruments of the Rosetta Plasma Consortium are providing close-up views of the solar-wind interaction with a comet from its dormancy into a period of significant coma development. Although a bow shock has not yet developed, the interactions so far involve significant deflection of the solar wind; pickup of cometary ions, charge exchange of solar-wind ions by the coma resulting in He+ and H- ions being entrained in the solar wind; the generation of low-frequency 10 - 100 mHz magnetic waves near the comet; electric-fields and waves in the range from DC up to 3.5 MHz, and significant plasma density enhancements, particularly over the neck of the comet. Also observed are negatively-charged nanograins with energies exceeding 20 keV and monoenergetic electron beams (up to 400 eV) indicative of negative charging of shaded regions of the nucleus. As the comet moves closer to the Sun these effects should increase along with the appearance of other expected effects such as a diamagnetic cavity, ionopause, and bow shock along with possibly other new and unexpected plasma and field phenomena.

  20. Proton corebeam system in the expanding solar wind: Hybrid simulations

    E-print Network

    California at Berkeley, University of

    Proton corebeam system in the expanding solar wind: Hybrid simulations Petr Hellinger1,2 and Pavel 9 November 2011. [1] Results of a twodimensional hybrid expanding box simulation of a proton to a decrease of the ratio between the proton perpendicular and parallel temperatures as well as to an increase

  1. Solar wind interactions with Comet 19P\\/Borrelly

    Microsoft Academic Search

    D. T Young; F. J Crary; J. E Nordholt; F. Bagenal; D. Boice; J. L Burch; A. Eviatar; R. Goldstein; J. J. Hanley; D. J Lawrence; D. J McComas; R. Meier; D. Reisenfeld; K. Sauer; R. C Wiens

    2004-01-01

    The Plasma Experiment for Planetary Exploration (PEPE) made detailed observations of the plasma environment of Comet 19P\\/Borrelly during the Deep Space 1 (DS1) flyby on September 22, 2001. Several distinct regions and boundaries have been identified on both inbound and outbound trajectories, including an upstream region of decelerated solar wind plasma and cometary ion pickup, the cometary bow shock, a

  2. The Helium Component of Solar Wind Velocity Streams

    Microsoft Academic Search

    J. Hirshberg; J. R. Asbridge; D. E. Robbins

    1974-01-01

    Systematic variations of the properties of the helium constituent of the solar wind in the velocity streams are described. It is found that the helium abundance na\\/n, varies by about a factor of 2 as the stream is crossed. The velocity of the helium differs from that of the hydrogen by a few kilometers per second throughout much of the

  3. Solar Wind Simulations Based on Ooty IPS Data

    NASA Astrophysics Data System (ADS)

    Muehe, S. C.; Kim, T. K.; Pogorelov, N. V.

    2014-12-01

    The solar wind is a constantly-flowing stream of charged particles that expands from the sun's outer atmosphere into interplanetary space. This plasma carries the sun's magnetic field along with it, where it interacts with and causes disruptions in the earth's magnetic field. Our understanding of the solar wind is vital to efforts toward minimizing the impact of these disturbances on both ground and space-based systems. Using interplanetary scintillation data gathered by the ground-based Ooty Radio Telescope (ORT) in India, we have constructed boundary maps of solar wind velocities at 1 day intervals. For a simple, first approximation, we use what is called the "P-point" method to crudely estimate the solar wind velocity at the point of closest approach to the Sun along each line of sight. Then we trace the P-point values back to a spherical surface at 0.2 AU where we interpolate them to a structured gird. The resulting boundary maps can serve as the initial input to a time-dependent MHD tomography program being developed at the University of Alabama in Huntsville.

  4. Solar wind interaction with Comet Bennett (1969i

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Rahe, J.; Donn, B. D.; Neugebauer, M.

    1972-01-01

    The relations are examined between the solar-wind and Comet Bennett during the period 23 March to 5 April 1970. A large kink was observed in the ion tail of the comet on April 4, but no solar wind stream was observed in the ecliptic plane which could have caused the kink. Thus, either there was no correlation between the solar wind at the earth and that at Comet Bennett (which was 40 deg above the ecliptic) or the kink was caused by something other than a high-speed stream. The fine structure visible in photographs of the kink favors the second of these alternatives. It is shown that a shock probably passed through Comet Bennett on March 31, but no effect was seen in photographs of the comet. A stream preceded by another shock and a large abrupt change in momentum flux might have intercepted the comet between 24 March and 28 March, but again no effect was seen in photographs of the Comet. In view of these results, the possibility must be considered that a large, abrupt change in momentum flux of the solar-wind is neither necessary nor sufficient to cause a large kink in a comet tail.

  5. Livestock water pumping with wind and solar power

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent developments in pumping technologies have allowed for efficient use of renewable energies like wind and solar to power new pumps for remote water pumping. A helical type, positive displacement pump was developed a few years ago and recently modified to accept input from a variable power sourc...

  6. Exospheric distributions of minor ions in the solar wind

    Microsoft Academic Search

    V. Pierrard; H. Lamy; J. Lemaire

    2004-01-01

    We investigate the acceleration of heavy solar wind ions on the basis of an exospheric Lorentzian model and show that the heavy ions can flow faster than the protons when their temperatures in the corona are more than proportional to their mass. The Lorentzian kinetic exospheric model [Pierrard and Lemaire, 1996], initially developed only for electrons and protons of the

  7. Solar wind vs magnetosheath turbulence and Alfvén vortices

    Microsoft Academic Search

    O. Alexandrova

    2008-01-01

    In this paper we give firstly a broad review of the space plasma turbulence around the ion characteristic space and temporal scales within two natural laboratories, the solar wind and the Earth magnetosheath. In both regions power law spectra of magnetic fluctuations are observed. In both regions these spectra have a break in the vicinity of the ion cyclotron frequency.

  8. HEMISPHERIC ASYMMETRIES IN THE POLAR SOLAR WIND OBSERVED BY ULYSSES NEAR THE MINIMA OF SOLAR CYCLES 22 AND 23

    SciTech Connect

    Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; McComas, D. J. [Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 (United States); Pogorelov, N. V. [Physics Department, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2013-05-10

    We examined solar wind plasma and interplanetary magnetic field (IMF) observations from Ulysses' first and third orbits to study hemispheric differences in the properties of the solar wind and IMF originating from the Sun's large polar coronal holes (PCHs) during the declining and minimum phase of solar cycles 22 and 23. We identified hemispheric asymmetries in several parameters, most notably {approx}15%-30% south-to-north differences in averages for the solar wind density, mass flux, dynamic pressure, and energy flux and the radial and total IMF magnitudes. These differences were driven by relatively larger, more variable solar wind density and radial IMF between {approx}36 Degree-Sign S-60 Degree-Sign S during the declining phase of solar cycles 22 and 23. These observations indicate either a hemispheric asymmetry in the PCH output during the declining and minimum phase of solar cycles 22 and 23 with the southern hemisphere being more active than its northern counterpart, or a solar cycle effect where the PCH output in both hemispheres is enhanced during periods of higher solar activity. We also report a strong linear correlation between these solar wind and IMF parameters, including the periods of enhanced PCH output, that highlight the connection between the solar wind mass and energy output and the Sun's magnetic field. That these enhancements were not matched by similar sized variations in solar wind speed points to the mass and energy responsible for these increases being added to the solar wind while its flow was subsonic.

  9. The Plasma Magnet for Sailing the Solar Wind

    NASA Astrophysics Data System (ADS)

    Slough, John

    2005-02-01

    Plasma sail propulsion based on the plasma magnet is a unique system that taps the ambient energy of the solar wind with minimal energy and mass requirements. The coupling to the solar wind is made through the generation of a large-scale (˜> 30 km) dipolar magnetic field. Unlike the original magnetic sail concept, the coil currents are conducted in a plasma rather than a superconducting coil. In this way the mass of the sail is reduced by orders of magnitude for the same thrust power. The plasma magnet consists of a pair of polyphase coils that produce a rotating magnetic field (RMF) that drives the necessary currents in the plasma to inflate and maintain the large-scale magnetic structure. The plasma magnet is deployed by the Lorentz self-force on the plasma currents, expanding outward in a disk-like shape until the expansion is halted by the solar wind pressure. It is virtually propellantless as the intercepted solar wind replenishes the small amount of plasma required to carry the magnet currents. Unlike a solid magnet or sail, the plasma magnet expands with falling solar wind pressure to provide constant thrust. A small prototype plasma magnet has been built and tested. The RMF coils generated over 10 kA of plasma currents with a radial expansion pressure sufficient to expand the dipole field to well over the 30 km scale that would supply as much as 5 MW of thrust power. The antenna and driver need weigh no more than ˜ 10 kg, and can operate from a 300 V supply. With the predicted scaling with size, it is possible to test the concept in the laboratory with a greatly enhanced laboratory solar wind source. Plans for a laboratory scaled experiment will be outlined that incorporate an intensified solar wind source and thrust measurement to assess the power gain predicted. With the successful demonstration of thrust power at the several hundred kW level, a large tank test would be the next step, and provide the final confirmation of the scaling needed for a space-based demonstration.

  10. Auroral Acceleration, Solar Wind Driving, and Substorm Triggering (Invited)

    NASA Astrophysics Data System (ADS)

    Newell, P. T.; Liou, K.

    2010-12-01

    We use a data base of 4861 substorms identified by global UV images to investigate the substorm cycle dependence of various types of aurora, and to obtain new results on substorm triggering by external driving. Although all types of aurora increase at substorm onset, broadband (Alfvénic) aurora shows a particular association with substorms, and, especially, substorm onset. While diffuse electron and monoenergetic auroral precipitating power rises by 79% and 90% respectively following an onset, broadband aurora rises by 182%. In the first 10-15 minutes following onset, the power associated with Alfvénic acceleration is comparable to monoenergetic acceleration (also called “inverted-V” events). In general, this is not the case prior to onset, or indeed, during recovery. The rise time of the electron diffuse aurora following onset is much slower, about 50 minutes, and thus presumably extends into recovery. We also re-investigate the issue of solar wind triggering of substorms by considering not just changes in the solar wind prior to onset, but how the pattern of changes differs from random and comparable epochs. We verify that a preonset reduction of solar wind driving (“northward turning” in the simplest case of IMF Bz) holds for the superposed epoch mean of the ensemble. Moreover, this reduction is not the result of a small number of substorms with large changes. The reduction starts about 20 min prior to substorm onset, which, although a longer delay than previously suggested, is appropriate given the various propagation time delays involved. Next, we compare the IMF to random solar wind conditions. Not surprisingly, solar wind driving prior to onset averages somewhat higher than random. Although about a quarter of substorms occur for steady northward IMF conditions, more general coupling functions such as the Kan-Lee electric field, the Borovosky function, or our d?MP/dt, show very few substorms occur following weak dayside merging. We assembled a data base of solar wind times with slightly elevated conditions, chosen to resemble the integrated driving typical before substorm onsets, but otherwise randomly occuring. We looked at how the IMF subsequently changed after these random elevations, compared to the changes preceding substorms. It turns out that mere reversion to the mean leads to a “northward turning” after the imposed selection criterion end. Thus (slightly generalizing the view of Morley and Freeman), substorms require solar wind driving which produces dayside merging, but external triggering is probably insignificant.

  11. Exploring Solar-Wind/Magnetosphere/Ionosphere Connections (Invited)

    NASA Astrophysics Data System (ADS)

    Borovsky, J. E.; Denton, M. H.; Lavraud, B.

    2009-12-01

    Superposed-epoch analysis of several data sets is employed to study the coupled solar-wind/magnetosphere/ionosphere system. Three stormtime couplings are highlighted. (1) During CIR-driven storms the enhanced solar-wind density owing to the compression of the slow wind produces a superdense plasma sheet in the magnetosphere which is temporally connected to the stormtime dropout and recovery of relativisitic electrons in the outer radiation belt. (2) During CIR-driven storms, the reversed IMF sector structure upstream of the stream interface drives a calm before the storm and the calm results in a filling of the outer plasmasphere which in turn results in a pre-storm decay of the outer electron radiation belt. (3) During CME- or CIR-driven storms a calm before the storm leads to a cool dense plasma sheet which results in better ring-current fuel and a larger Dst perturbation during the storm.

  12. Model for energy transfer in the solar wind: Model results

    NASA Technical Reports Server (NTRS)

    Barnes, A. A., Jr.; Hartle, R. E.

    1972-01-01

    A description is given of the results of solar wind flow in which the heating is due to (1) propagation and dissipation of hydromagnetic waves generated near the base of the wind, and (2) thermal conduction. A series of models is generated for fixed values of density, electron and proton temperature, and magnetic field at the base by varying the wave intensity at the base of the model. This series of models predicts the observed correlation between flow speed and proton temperature for a large range of velocities. The wave heating takes place in a shell about the sun greater than or approximately equal to 10 R thick. We conclude that large-scale variations observed in the solar wind are probably due mainly to variation in the hydromagnetic wave flux near the sun.

  13. Solar wind induced magnetic field around the unmagnetized Earth

    E-print Network

    G. T. Birk; H. Lesch; C. Konz

    2004-04-29

    The Earth is a planet with a dipolar magnetic field which is agitated by a magnetized plasma wind streaming from the Sun. The magnetic field shields the Earth's surface from penetrating high energy solar wind particles, as well as interstellar cosmic rays. The magnetic dipole has reversed sign some hundreds of times over the last 400 million years. These polarity reversals correspond to drastic breakdowns of the dynamo action. The question arises what the consequences for the Earth's atmosphere, climate, and, in particular, biosphere are. It is shown by kinematic estimates and three-dimensional plasma-neutral gas simulations that the solar wind can induce very fast a magnetic field in the previously completely unmagnetized Earth's ionosphere that is strong enough to protect Earth from cosmic radiations comparable to the case of an intact magnetic dynamo.

  14. The interaction between the Moon and the solar wind

    E-print Network

    Holmström, M; Futaana, Y; Nilsson, H

    2011-01-01

    We study the interaction between the Moon and the solar wind using a three-dimensional hybrid plasma solver. The proton fluxes and electromagnetical fields are presented for typical solar wind conditions with different magnetic field directions. Several features are consistent with a fluid interaction, e.g., the presence of a rarefaction cone, and an increased magnetic field in the wake. There are however several kinetic features of the interaction. We find kinks in the magnetic field at the wake boundary. There are also density and magnetic field variations in the far wake, maybe from an ion beam instability related to the wake refill. The results are compared to observations by the WIND spacecraft during a wake crossing. The model magnetic field and ion velocities are in agreement with the measurements. The density and the electron temperature in the central wake are not as well captured by the model, probably from the lack of electron physics in the hybrid model.

  15. Large Scale Wind and Solar Integration in Germany

    SciTech Connect

    Ernst, Bernhard; Schreirer, Uwe; Berster, Frank; Pease, John; Scholz, Cristian; Erbring, Hans-Peter; Schlunke, Stephan; Makarov, Yuri V.

    2010-02-28

    This report provides key information concerning the German experience with integrating of 25 gigawatts of wind and 7 gigawatts of solar power capacity and mitigating its impacts on the electric power system. The report has been prepared based on information provided by the Amprion GmbH and 50Hertz Transmission GmbH managers and engineers to the Bonneville Power Administration (BPA) and Pacific Northwest National Laboratory representatives during their visit to Germany in October 2009. The trip and this report have been sponsored by the BPA Technology Innovation office. Learning from the German experience could help the Bonneville Power Administration engineers to compare and evaluate potential new solutions for managing higher penetrations of wind energy resources in their control area. A broader dissemination of this experience will benefit wind and solar resource integration efforts in the United States.

  16. Solar Winds Driven by Nonlinear Low-Frequency Alfven Waves from the Photosphere : Parametric Study for Fast/Slow Winds and Disappearance of Solar Winds

    E-print Network

    Takeru K. Suzuki; Shu-ichiro Inutsuka

    2006-05-22

    (abridged) We investigate how the properties of the corona and solar wind in the open coronal holes depend on the properties of the magnetic fields and their footpoint motions at the surface, by perfoming 1D MHD simulations from the photosphere to 0.3 or 0.1AU. We impose low-frequency (10^6K by the dissipation of the Alfven waves through compressive-wave generation and wave reflection in the case of the sufficient wave input with photospheric amplitude, > 0.7km/s. The density, and accordingly the mass flux, of solar winds show a quite sensitive dependence on because of an unstable aspect of the heating by the nonlinear Alfven waves. A case with =0.4km/s gives ~50 times smaller mass flux than the fiducial case for the fast wind with =0.7km/s; solar wind almost disappears only if becomes half. We also find that the solar wind speed has a positive correlation with B/f_max, which is consistent with recent observations. We finally show that both fast and slow solar winds can be explained by the single process, the dissipation of the low-frequency Alfven waves, with different sets of and B/f_max. Our simulations naturally explain the observed (i) anticorrelation of the solar wind speed and the coronal temperature and (ii) larger amplitude of the Alfvenic fluctuations in the fast winds. In Appendix, we also explain our implementation of the outgoing boundary condition of the MHD waves with some numerical tests.

  17. Global aspects of solar wind ionosphere interactions

    Microsoft Academic Search

    T. E. Moore; M.-C. Fok; D. C. Delcourt; S. P. Slinker; J. A. Fedder

    2007-01-01

    Recent observations have quantified the auroral wind O+ outflow in response to magnetospheric inputs to the ionosphere, notably Poynting energy flux and precipitating electron density. For moderate to high activity periods, ionospheric O+ is observed to become a significant or dominant component of plasma pressure in the inner plasma sheet and ring current regions. Using a global circulation model of

  18. Plasma observations of the solar wind interaction with Mars

    SciTech Connect

    Vaisberg, O.L. (Space Research Institute, Moscow (USSR)); Luhmann, J.G.; Russell, C.T. (Univ. of California, Los Angeles (USA))

    1990-08-30

    Measurements with the plasma analyzers on the Mars-2, 3 and 5 spacecraft show that Mars deflects a large fraction of the incoming solar wind flow to form a strong bow shock. The bow shock is about 1.41 Rm from the center of the planet at the subsolar point and about 2.40 Rm at the terminator. These distances are similar to those for Venus at times of moderate solar activity. The inferred effective obstacle altitude is about 400-700 km. An ion cushion has been found which is similar in its properties to the Venus magnetic barrier. The formation of this cushion appears to cause the deflection of the solar wind. Inside the cushion but well above the ionosphere is found a region where the ions are at the background, the electrons are cool and the magnetic pressure dominates. This region may resemble a planetary magnetosphere.

  19. Alfven Wave Effects in Radio Scattering Observations of the Inner Solar Wind

    Microsoft Academic Search

    J. K. Harmon

    2003-01-01

    Microwave radio scattering and scintillation observations reveal a variety of distinctive characteristics in the density fluctuation spectrum and scintillation velocity field of the solar wind inside 25 solar radii. Any plasma wave or turbulence model of the corona and solar wind must be consistent with these radio results as well as with in situ spacecraft measurements outside 60 solar radii.

  20. Observation of the multifractal spectrum in solar wind turbulence by Ulysses at high latitudes

    Microsoft Academic Search

    Anna Wawrzaszek; Wieslaw M. Macek

    2010-01-01

    The aim of our study is to examine the question of multifractal scaling properties of turbulence in the solar wind at high latitudes. We analyze time series of the velocities of the solar wind during solar minimum (1994–1997, 2006–2007) at various heliographic latitudes measured in situ by Ulysses, which is the only mission that has investigated parameters of the solar

  1. Slow wind and magnetic topology in the solar minimum corona in 1996-1997

    Microsoft Academic Search

    E. Antonucci; L. Abbo; M. A. Dodero

    2005-01-01

    This study examines the physical conditions of the outer solar corona in order to identify the regions where the slow solar wind is accelerated and to investigate the latitudinal transition from slow to fast wind during the minimum of the solar cycle. The analysis is based on observations of six streamers obtained during the years of solar minimum, 1996 and

  2. Turbulent Alfven Waves as a Solar Wind Driver: Results from a new 4D model for the Solar Corona and Solar Wind

    Microsoft Academic Search

    R. Oran; I. Sokolov; I. I. Roussev; R. A. Frazin; T. I. Gombosi

    2009-01-01

    The mechanisms responsible for plasma heating in the solar corona and solar wind acceleration are still not well understood. Turbulent MHD waves have been suggested as a possible mechanism, which both heats the plasma via wave energy dissipation and accelerates it due to the wave pressure gradient force. In order to account for these processes, a self-consistent model of the

  3. Solar Panel Buffeted by Wind at Phoenix Site

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Winds were strong enough to cause about a half a centimeter (.19 inch) of motion of a solar panel on NASA's Phoenix Mars lander when the lander's Surface Stereo Imager took this picture on Aug. 31, 2008, during the 96th Martian day since landing.

    The lander's telltale wind gauge has been indicating wind speeds of about 4 meters per second (9 miles per hour) during late mornings at the site.

    These conditions were anticipated and the wind is not expected to do any harm to the lander.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  4. The Latitude Dependence of the Effect of Pinatubo on Stratospheric Ozone

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.; Douglass, Anne R.

    2004-01-01

    Statistical analysis of TOMS and SBLT total ozone data indicate that the eruption of Pinatubo in 1991 led to a significant decrease in ozone at northern midlatitudes with little or no effect at southern midlatitudes. We argue that this puzzling absence of a southern hemisphere effect may be an artifact of the statistical analysis. We have run a 3D CTM simulation of the past 30 years of stratospheric photochemistry with variable forcing due to chlorine/bromine compounds, solar ultraviolet radiation, and volcanic aerosols. This integration used winds from the FVGCM, which has similar interannual variability to the atmosphere. When this CTM output was examined with a standard time-series analysis, we found an effect of Pinatubo in the southern hemisphere, but not in the northern hemisphere. We then reran the CTM without volcanic aerosols. The subtraction of the two simulations indicated that, as expected, that Pinatubo affected both hemispheres in the model. This means that the northern hemisphere effect was in the model but did not show up in the statistical analysis. We also had an on-line parameterized chemical ozone tracer with seasonally repeating production and loss over the simulation. We used this as a dynamical surrogate to remove interannual variability from the original model output. The residual time series was then analyzed for the Pinatubo effect and we were able to find it in both hemispheres. We suggest that the combination of the two volcanoes, El Chichon and Pinatubo, with the solar cycle and interannual variability led to this problem of analysis in the northern hemisphere of our model. We furthermore suggest that a similar think may be occurring in the southern hemisphere of the data. An analysis of the atmosphere's southern hemisphere with a good dynamical surrogate may solve the mystery of the missing southern hemisphere effect of Pinatubo on ozone.

  5. Parallel and Perpendicular Heating of Solar Wind Protons by Kinetic Waves as Inferred from WIND Observations

    NASA Astrophysics Data System (ADS)

    He, J.; Wang, L.; Tu, C. Y.; Marsch, E.

    2014-12-01

    The solar wind may be heated non-adiabatically by Joule dissipation of coherent current structures or by wave-particle interaction with kinetic waves. In high-speed solar wind, where current structures of tangential-discontinuity type are rare and Alfven-like waves are abundant, wave-particle interaction may be a promising candidate for the heating mechanism. Here we address how the solar wind protons are heated parallel and perpendicularly based on the observations of proton velocity distributions and kinetic wave fluctuations from the WIND spacecraft. It is shown that solar wind protons consist of anisotropic core and beam populations with a relative field-aligned drift speed of ~VA between them. Both quasi-parallel left-handed Alfven-cyclotron waves (LH-ACWs) and quasi-perpendicular right-handed Alfven-cyclotron waves / kinetic Alfven waves (RH-ACWs/KAWs) are also identified. It seems that the proton velocity distribution contours may be shaped by left-cyclotron resonance with quasi-parallel LH-ACWs for its anisotropic core components, Landau resonance with quasi-perpendicular KAWs for its beam drift, and right-cyclotron resonance with quasi-perpendicular RH-ACWs for its anisotropic beam component. Plasma instability is also investigated from the data, which shows that the core component anisotropy is usually unstable and may be responsible for the observed LH-ACWs with enhanced fluctuations; whereas the beam drift is stable and no RH-fast/whistler waves are observed. Moreover, the solar wind protons are observed, with the unprecedented cadence of 3s, to be highly dynamic in their velocity distributions with an apparent alternation between the stretching and contracting of the drifted beam, which may be connected with amplitude intermittency of associated waves.

  6. An optimum solar wind coupling function for the AL index

    NASA Astrophysics Data System (ADS)

    McPherron, Robert L.; Hsu, Tung-Shin; Chu, Xiangning

    2015-04-01

    We define a coupling function as a product of solar wind factors that partially linearizes the relation between it and a magnetic index. We consider functions that are a product of factors of solar wind speed V, density N, transverse magnetic field B?, and interplanetary magnetic field (IMF) clock angle ?c each raised to a different power. The index is the auroral lower (AL index) which monitors the strength of the westward electrojet. Solar wind data 1995-2014 provide hour averages of the factors needed to calculate optimum exponents. Nonlinear inversion determines both the exponents and linear prediction filters of short data segments. The averages of all exponents are taken as optimum exponents and for V, N, B?, and sin(?c/2) are [1.92, 0.10, 0.79, 3.67] with errors in the second decimal. Hourly values from 1966 to 2014 are used next to calculate the optimum function (opn) and the functions VBs (eys), epsilon (eps), and universal coupling function (ucf). A yearlong window is advanced by 27 days calculating linear prediction filters for the four functions. The functions eps, eys, ucf, and opn, respectively, predict 43.7, 61.2, 65.6, and 68.3% of AL variance. The opn function is 2.74% better than ucf with a confidence interval 2.60-2.86%. Coupling strength defined as the sum of filter weights (nT/mV/m) is virtually identical for all functions and varies systematically with the solar cycle being strongest (188 nT/mV/m) at solar minimum and weakest (104) at solar maximum. Saturation of the polar cap potential approaching solar maximum may explain the variation.

  7. Stratospheric ozone decrease due to chlorofluoromethane photolysis - Predictions of latitude dependence

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.; Whitten, R. C.; Woodward, H. T.; Capone, L. A.; Riegel, C. A.; Gaines, S.

    1980-01-01

    A two-dimensional model is used to predict the 1990 reduction in ozone due to the chlorine compounds formed by chlorofluoromethane (CFM) photolysis when the CFM release rate is held constant at the 1975 value. The predicted globally averaged ozone reduction of 3.5% is similar to that predicted by one-dimensional models that did not include chlorine nitrate chemistry, and used lower values for the reactions rates of NO + HO2 yielding NO2 + OH and O3 + HO2 yielding OH + 2O2. When the 5.7 ppbv increase in chlorine compounds predicted by one-dimensional models to occur under steady-state conditions is simulated by the two-dimensional model, a 26% decrease in atmospheric ozone is predicted. The latitude dependence of the ozone reduction is discussed in terms of the relevant photochemical reaction and transport. The chemical reactions that most strongly influence the meridional dependence of the ozone depletion are identified as those associated with the reactions of chlorine monoxide and atomic oxygen, the recombination of ozone and atomic oxygen, and the photodissociation of molecular oxygen.

  8. Neutral Solar Wind Generated by Lunar Exospheric Dust at the Terminator

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Stubbs, Timothy J.

    2007-01-01

    We calculate the flux of neutral solar wind observed on the lunar surface at the terminator due to solar wind protons penetrating exospheric dust with: (1) grains larger that 0.1 microns and (2) grains larger than 0.01 microns. For grains larger than 0.1 microns, the ratio of the neutral solar wind to solar wind flux is estimated to be approx.10(exp -4)-10(exp -3) at solar wind speeds in excess of 800 km/s, but much lower (less than 10(exp -5) at average to low solar wind speeds. However, when the smaller grain sizes are considered, the ratio of the neutral solar wind flux to solar wind flux is estimated to be greater than or equal to 10(exp -5) at all speeds and at speeds in excess of 700 km/s reaches 10(exp -3)-10(exp -2). These neutral solar wind fluxes are easily measurable with current low energy neutral atom instrumentation. Observations of neutral solar wind from the surface of the Moon could provide a very sensitive determination of the distribution of very small dust grains in the lunar exosphere and would provide data complementary to optical measurements at ultraviolet and visible wavelengths. Furthermore, neutral solar wind, unlike its ionized counterpart, is .not held-off by magnetic anomalies, and may contribute to greater space weathering than expected in certain lunar locations.

  9. Physics of the solar wind for the 1975-1978 IUUG Quadrennial Report

    NASA Technical Reports Server (NTRS)

    Barnes, A.

    1979-01-01

    The paper surveys topics related to the origin, expansion, and acceleration of the solar wind and the plasma physics of the interplanetary medium. The study of the relationship between coronal holes and solar-wind streams, and the associated revision of ideas about solar wind acceleration and heating are reviewed. In addition, topics of hydromagnetic waves and turbulence, and interplanetary electrons, as items of particular importance during the past quadrennium, are discussed. While the research discussed was concerned with data taken near solar minimum, further solar-wind studies will concentrate on observations from the rising and maximum phases of the solar cycle.

  10. A porcupine Sun? Implications for the solar wind and Earth

    NASA Astrophysics Data System (ADS)

    Gibson, Sarah E.; Zhao, Liang

    2012-07-01

    The recent minimum was unusually long, and it was not just the case of the ``usual story'' slowed down. The coronal magnetic field never became completely dipolar as in recent Space Age minima, but rather gradually evolved into an (essentially axisymmetric) global configuration possessing mixed open and closed magnetic structures at many latitudes. In the process, the impact of the solar wind at the Earth went from resembling that from a sequence of rotating ``fire-hoses'' to what might be expected from a weak, omnidirectional ``lawn-sprinkler''. The previous (1996) solar minimum was a more classic dipolar configuration, and was characterized by slow wind of hot origin localized to the heliospheric current sheet, and fast wind of cold origin emitted from polar holes, but filling most of the heliosphere. In contrast, the more recent minimum solar wind possessed a broad range of speeds and source temperatures (although cooler overall than the prior minimum). We discuss possible connections between these observations and the near-radial expansion and small spatial scales characteristic of the recent minimum's porcupine-like magnetic field.

  11. Reconnection exhausts associated boundary turbulence in the solar wind

    NASA Astrophysics Data System (ADS)

    Voros, Zoltan; Sasunov, Jury; Semenov, Vladimir

    2013-04-01

    Recent analytical calculations on the Riemannian decay of currents sheets involving magnetic reconnection with skewed magnetic fields in the solar wind have shown that, large fractions of reconnection exhausts boundaries are tangential discontinuities, which can occasionally be Kelvin-Helmholtz (KH) unstable (Sasunov et al., 2012). In such cases, instead of a sharp Riemannian discontinuity, K-H instability associated multi-scale turbulence develops, leading to increased temperature, density and entropy across the boundary region. The goal of the present study is to investigate the statistical properties of K-H instability driven boundary turbulence and to connect the observed turbulent features to small-scale dissipation processes over kinetic scales. To this end we will use magnetic and plasma data from the WIND spacecraft for several cases of K-H unstable turbulent outflow boundaries in the solar wind. The relationship between second- and higher-order statistics obtained over the inertial range of turbulence and the occurrence of kinetic effects, such as plasma heating and temperature anisotropy, will be investigated. The obtained picture of turbulent boundary dissipation will be compared to the turbulent dissipation processes occurring in the pristine solar wind.

  12. Signatures of shock drivers in the solar wind and their dependence on the solar source location

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.

    1993-01-01

    Solar wind and energetic ion observations following 40 interplanetary shocks with well-established solar source locations have been examined in order to determine whether signatures characteristic of the coronal material forming the shock driver are present. The signatures considered include magnetic-field-aligned bidirectional ion flows observed by the ISEE 3 and IMP 8 spacecraft; bidirectional solar wind electron heat fluxes; solar wind plasma proton and electron temperature depressions; low-beta plasma; enhanced, low-variance magnetic fields; and energetic ion depressions. Several shock driver signatures are commonly observed following shocks originating from within about 50 deg of central meridian, and are generally absent for other events. We conclude that shock drivers generally extend up to about 100 deg in longitude, centered on the solar source longitude. Since shocks from central meridian events are not usually associated with all the shock driver signatures examined, the absence of a driver cannot be confirmed from consideration of one of these signatures alone. We also find evidence that a few bidirectional energetic ion and solar wind electron heat flux events following shocks (in particular from far eastern sources) may occur on open field lines outside of shock drivers.

  13. Dayside Erosion During Intervals of Tenuous Solar Wind

    NASA Astrophysics Data System (ADS)

    Farrugia, C. J.; Muehlbachler, S.; Torbert, R. B.; Biernat, H. K.

    2001-12-01

    We present six data examples where we infer erosion of the dayside magnetosphere during intervals of very tenuous solar wind (density < 1 cm-3). The interplanetary observations were made by the Wind spacecraft when the average solar wind dynamic pressure P dyn and the interplanetary magnetic field (IMF) Bz were in the ranges (0.07, 0.62) nPa and (-7.6, -0.9) nT, respectively. The inner magnetospheric signature of erosion we focus on is a decrease in the strength of the geostationary magnetic field, as monitored by NOAA's GOES spacecraft. We obtain this decrease as a function of IMF Bz by comparing each event with a reference day, May 11, 1999. During the reference day the lowest P dyn of the set was attained (0.07 nPa), IMF Bz > 0, and the geomagnetic field at geostationary orbit was dipolar. The central point we make is that although compared to the reference day the P dyn in each event is higher, the strength of the geostationary field is weaker. We interpret this as evidence that the field compression due to P dyn has been overcome by the field depression due to erosion. Correcting empirically for the compression of the geostationary field due to solar wind dynamic pressure, we find that for the tenuous solar winds we consider the decrease of the geostationary field, ? BGS, is related to IMF Bz as ? BGS (nT)= -2.8 + 2.3 Bz (nT). This work is supported by NASA Living with a Star Grant NAG5-10883 and DARA grant 50 OC 8911 0.

  14. Detection of fast nanoparticles in the solar wind

    SciTech Connect

    Meyer-Vernet, N.; Maksimovic, M.; Lecacheux, A.; Le Chat, G. [LESIA, Observatoire de Paris, CNRS, U. Paris Diderot, UPMC, 5 Place Janssen, 92190 Meudon (France); Czechowski, A. [Space Research Centre, Polish Academy of Sciences, Bartycka 18 A PL-00-716, Warsaw (Poland); Mann, I. [School of Science and Engineering, Kindai University Kowakae 3-4-1, Osaka, 577-8502 (Japan); Goetz, K. [School of Physics and Astronomy, University of Minnesota, Minneapolis (United States); Kaiser, M. L.; Cyr, O. C. St. [NASA-GSFC, Greenbelt, MD 20771 (United States); Bale, S. D. [Space Sciences Laboratory, University of California, Berkeley (United States)

    2010-03-25

    Dust grains in the nanometer range bridge the gap between atoms and larger grains made of bulk material. Their small size embodies them with special properties. Due to their high relative surface area, they have a high charge-to-mass ratio, so that the Lorentz force in the solar wind magnetic field exceeds the gravitational force and other forces by a large amount, and they are accelerated to a speed of the order of magnitude of the solar wind speed. When such fast nanoparticles impact a spacecraft, they produce craters whose matter vaporises and ionises, yielding transient voltages as high as do much larger grains of smaller speed. These properties are at the origin of their recent detection at 1 AU in the solar wind. We discuss the detection of fast nanoparticles by wave instruments of different configurations, with applications to the recent detections on STEREO/WAVES and CASSINI/RPWS. Finally we discuss the opportunities for nanoparticle detection by wave instruments on future missions and/or projects in the inner heliosphere such as Bepi-Colombo and Solar Orbiter.

  15. Small solar wind transients: Stereo-A observations in 2009

    SciTech Connect

    Yu, W.; Farrugia, C. J.; Galvin, A. B.; Simunac, K. D. C.; Popecki, M. A.; Lugaz, N. [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Kilpua, E. K. J. [Dept. of Physics, Division of Geophysics and Astronomy, University of Helsinki (Finland); Moestl, C. [Institute of Physics, University of Graz, 8010 Graz, Austria and Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Luhmann, J. G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Opitz, A.; Sauvaud, J.-A. [Institut de Recherche en Astrophysique et Planetologie (CNRS-UPS), Universite de Toulouse, F-31038, Toulouse (France)

    2013-06-13

    Year 2009 was the last year of a long and pronounced solar activity minimum. In this year the solar wind in the inner heliosphere was for 90% of the time slow (< 450 km s{sup -1}) and with a weaker magnetic field strength compared to the previous solar minimum 1995-1996. We choose this year to present the results of a systematic search for small solar wind transients (STs) observed by the STEREO-Ahead (ST-A) probe. The data are from the PLASTIC and IMPACT instrument suites. By 'small' we mean a duration from {approx}1 to 12 hours. The parameters we search for to identify STs are (i) the total field strength, (ii) the rotation of the magnetic field vector, (iii) its smoothness, (iv) proton temperature, (v) proton beta, and (vi) Alfven Mach number. We find 45 examples. The STs have an average duration of {approx}4 hours. Ensemble averages of key quantities are: (i) maximum B = 7.01 nT; (ii) proton {beta}= 0.18; (iii) proton thermal speed = 20.8 km s{sup -1}; and (iv) Alfven Mach number = 6.13. No distinctive feature is found in the pitch angle distributions of suprathermal electrons. Our statistical results are compared with those of STs observed near Earth by Wind during 2009.

  16. Detection of fast nanoparticles in the solar wind

    NASA Astrophysics Data System (ADS)

    Meyer-Vernet, N.; Czechowski, A.; Mann, I.; Maksimovic, M.; Lecacheux, A.; Goetz, K.; Kaiser, M. L.; Cyr, O. C. St.; Bale, S. D.; Le Chat, G.

    2010-03-01

    Dust grains in the nanometer range bridge the gap between atoms and larger grains made of bulk material. Their small size embodies them with special properties. Due to their high relative surface area, they have a high charge-to-mass ratio, so that the Lorentz force in the solar wind magnetic field exceeds the gravitational force and other forces by a large amount, and they are accelerated to a speed of the order of magnitude of the solar wind speed. When such fast nanoparticles impact a spacecraft, they produce craters whose matter vaporises and ionises, yielding transient voltages as high as do much larger grains of smaller speed. These properties are at the origin of their recent detection at 1 AU in the solar wind. We discuss the detection of fast nanoparticles by wave instruments of different configurations, with applications to the recent detections on STEREO/WAVES and CASSINI/RPWS. Finally we discuss the opportunities for nanoparticle detection by wave instruments on future missions and/or projects in the inner heliosphere such as Bepi-Colombo and Solar Orbiter.

  17. Turbulence generated by flux tube instabilities in the solar wind

    NASA Astrophysics Data System (ADS)

    Vörös, Zoltan; Zaqarashvili, Teimuraz; Sasunov, Jury; Semenov, Vladimir; Bruno, Roberto

    2015-04-01

    Magnetic flux tubes represent basic structures on the Sun and in the solar wind. Flux tubes of solar origin can become magnetically twisted at photospheric, chromospheric or coronal levels and transported into interplanetary space. Twisted or untwisted flux tubes can also be generated by magnetic reconnection in the solar wind. We show here that flux tube instabilities, such as the Kelvin-Helmholtz and the kink instabilities, may significantly contribute to the local generation of turbulence, reconnection and dissipation in the solar wind. The associated "fresh" turbulence may change the field and plasma conditions supporting different local dissipation mechanisms at their characteristic wavenumbers. Recent analytical and numerical calculations show that twisted tubes embedded into twisted external magnetic fields are Kelvin-Helmholtz unstable even for sub-Alfvenic flows. Moving tubes with strong twists are unstable against the kink instability resulting in magnetic reconnection and dissipation. Vörös et al., ApJL, 797:L10, 2014. Zaqarashvili et al., A&A, 561, A62, 2014. Zaqarashvili et al., ApJL, 783:L19, 2014.

  18. Generalized similarity in magnetohydrodynamic turbulence as seen in the solar corona and solar wind

    NASA Astrophysics Data System (ADS)

    Chapman, S. C.; Leonardis, E.; Nicol, R. M.; Foullon, C.

    2010-12-01

    A key property of turbulence is that it can be characterized and quantified in a robust and reproducible way in terms of the ensemble averaged statistical properties of fluctuations. Importantly, fluctuations associated with a turbulent field show similarity or scaling in their statistics and we test for this in observations of magnetohydrodynamic turbulence in the solar corona and solar wind with both power spectra and Generalized Structure Functions. Realizations of turbulence that are finite sized are known to exhibit a generalized or extended self-similarity (ESS). ESS was recently demonstrated in magnetic field timeseries of Ulysses single point in-situ observations of fluctuations of quiet solar wind for which a single robust scaling function was found [1-2]. Flows in solar coronal prominences can be highly variable, with dynamics suggestive of turbulence. The Hinode SOT instrument provides observations (images) at simultaneous high spatial and temporal resolution which span several decades in both spatial and temporal scales. We focus on specific Calcium II H-line observations of solar quiescent prominences with dynamic, highly variable small-scale flows. We analyze these images from the perspective of a finite sized turbulent flow. We discuss this evidence of ESS in the SOT images and in Ulysses solar wind observations- is there a single universal scaling of the largest eddies in the finite range magnetohydrodynamic turbulent flow? [1] S. C. Chapman, R. M. Nicol, Generalized Similarity in Finite Range Solar Wind Magnetohydrodynamic Turbulence, Phys. Rev. Lett., 103, 241101 (2009) [2] S. C. Chapman, R. M. Nicol, E. Leonardis, K. Kiyani, V. Carbone, Observation of universality in the generalized similarity of evolving solar wind turbulence as seen by ULYSSES, Ap. J. Letters, 695, L185, (2009)

  19. Observations of the solar wind speed near the sun

    SciTech Connect

    Grall, R. R.; Coles, Wm. A.; Klinglesmith, M. T. [Electrical and Computer Engineering, University of California, San Diego (United States)

    1996-07-20

    Two-antenna scintillation (IPS) observations can provide accurate measurements of the velocity with which electron density fluctuations drift past the line of sight. These fluctuations can be used as tracers for the solar plasma and allow us to estimate the solar wind velocity near the Sun where spacecraft have not yet penetrated. We present recent IPS measurements made with the EISCAT and VLBA arrays. We have found that by using baselines which are several times the scale size of the diffraction pattern we are able to partially deconvolve the line of sight integration which affects remote sensing data. The long baselines allow the fast and slow components of the solar wind to be separated and their velocities estimated individually. In modeling IPS it is important that the scattering be 'weak' because the model then requires only 1 spatial parameter instead of 3. EISCAT can only operate near 933MHz which limits the observation to outside of 18R{sub {center_dot}}, however the VLBA has higher frequency receivers which allow it to observe inside of 15R{sub {center_dot}}. The density variance {delta}N{sub e}{sup 2} in the fast wind is a factor of 10-15 less than in the slow (Coles et al., 1995) making it necessary to consider the entire line of sight, particularly when the fast wind occupies the center portion. Using the point of closest approach and the average velocity to characterize the observation can lead to an incorrect interpretation of the data. We have compared our IPS observations with maps made from the Yohkoh soft X ray, HAO's white-light electron density, and Stanford magnetic field measurements as well as with the IMP8 and Ulysses spacecraft data to assist in placing the fast and slow wind. Here we have selected those observation from 1994 which were dominated by the southern coronal hole and have estimated a velocity acceleration profile for the fast solar wind between 7 and 100R{sub {center_dot}} which is presented in Figure 1. The observations suggest that the fast solar wind is fully developed by {approx_equal}7R{sub {center_dot}} and shows no acceleration over the distance range probed. It is also inconsistent with wave driven acceleration models which continue to show significant acceleration out past 20R{sub {center_dot}}. This talk has been submitted to Nature (Grall et al., 1995)

  20. Solar Wind Fluctuations and Their Consequences on the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Li, Xin-Lin

    2005-01-01

    Efforts have been made to extract the physical meaning of each term in our prediction model of the Dst index using the solar wind as the only input. The work has been published Journal of Geophysical Research (Temerin and Li, 21002). We found different terms in the model representing different current in the magnetospheric system and each current has different rise and decay times, with the symmetric ring current the slowest, then the partial ring current, then the tail current. We also have been trying to understand the physical meaning of the diffusion coefficient used in our prediction model of relativistic electron fluxes at geostationary orbit. The model reproduced the observations of MeV electron flux variations well, the diffusion coefficient had be assumed only die to local magnetic field fluctuations, leading to its 10th power dependence on the L. We have studied the theoretical derivation of the diffusion coefficient and we believe that the effect electric field fluctuations at smaller L could become more significant. We have expanded our previous radiation belt electron prediction model, which predicted MeV electron geosynchronous orbit based on solar wind measurements, to predict MeV electrons inside geosynchronous orbit. The model results are compared with measurements from Polar/CEPPAD. Prediction efficiencies of 0.56 and 0.54, respectively, at L=6 and L=4, have been achieved over the entire year of 1998. This work wa reported at 2003 Fall AGU and has been accepted for publication in Space Weather (Barker et al., 2005). We also have used simultaneous measurements of the upstream solar wind and of energetic electrons at geosynchronous orbit to analyze the response of electrons over a very wide energy range, 50 keV-6MeV, to solar wind variations. Enhancements of energetic electron fluxes over this whole energy range are modulated by the solar wind speed and the polarity of the interplanetary magnetic field (IMF). The solar wind speed seems to be a dominant controlling parameter for electrons of all energy. This work has been published in Space Weather (Li et al., 2005).