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1

Latitude-Dependent Temperature Variations at the Solar Limb  

NASA Astrophysics Data System (ADS)

We use observations from the solar aspect sensor of RHESSI to characterize the latitude dependence of the temperature of the photosphere at the solar limb. Previous observations have suggested the presence of a polar temperature excess as large as 1.5 K. The RHESSI observations, made with a rotating telescope in space, have great advantages in the rejection of systematic errors in the very precise photometry required for such an observation. This photometry is differential, i.e. relative to a mean limb-darkening function. The data base consists of about 1,000 images per day from linear CCDs with 1.73 arc sec square pixels, observing a narrow band (12nm FWHM) at 670 nm. Each image shows a chord crossing the disk at a different location as the spacecraft rotates and precesses around its average solar pointing. We fit an average limb-darkening function and reassemble the residuals into synoptic maps of differential intensity variations as function of position angle. We further mask these images against SOHO/EIT 284A images in order to eliminate magnetic regions. The analysis establishes a limit on the quadrupole dependence of temperature (brightness) on position angle of 0.04 +/- 0.02 K. This results in a possible correction of our precise measurement of the solar oblateness which is smaller than its rms error of 0.14 mas.

Fivian, M. D.; Hudson, H. S.; Lin, R. P.; Zahid, H. J.

2009-12-01

2

Latitude-Dependent Temperature Variations at the Solar Limb  

NASA Astrophysics Data System (ADS)

We use observations from the solar aspect sensor of RHESSI to characterize the latitude dependence of the temperature of the photosphere at the solar limb. Previous observations have suggested the presence of a polar temperature excess as large as 1.5 K. The RHESSI observations, made with a rotating telescope in space, have great advantages in the rejection of systematic errors in the very precise photometry required for such an observation. This photometry is differential, i.e. relative to a mean limb-darkening function. The data base consists of about 1,000 images per day from linear CCDs with 1.73 arc sec square pixels, observing a narrow band (12nm FWHM) at 670 nm. Each image shows a chord crossing the disk at a different location as the spacecraft rotates and precesses around its average solar pointing. We fit an average limb-darkening function and reassemble the residuals into synoptic maps of differential intensity variations as function of position angle. We further mask these images against SOHO/EIT 284A images in order to eliminate magnetic regions. The analysis establishes limits on the quadrupole dependence of brightness (temperature) on position angle, a crucial unknown in our precise measurement of the solar oblateness.

Fivian, Martin; Hudson, H. S.; Lin, R. P.; Zahid, H. J.

2009-05-01

3

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

SciTech Connect

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.

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

2010-01-01

4

Latitude-Dependent Effects in the Stellar Wind of Eta Carinae  

NASA Technical Reports Server (NTRS)

The Homunculus reflection nebula around eta Carinae provides the rare opportunity to observe the spectrum of a star from more than one direction. In the case of eta Car, the nebula's geometry is known well enough to infer how wind profiles vary with latitude. We present STIS spectra of several positions in the Homunculus, showing directly that eta Car has an aspherical and axisymmetric stellar wind. P Cygni absorption in Balmer lines depends on latitude, with relatively high velocities and strong absorption near the polar axis. Stronger absorption at high latitudes is surprising, and it suggests higher mass flux toward the poles, perhaps resulting from equatorial gravity darkening on a rotating star. Reflected profiles of He I lines are more puzzling, and offer clues to eta Car's wind geometry and ionization structure. During eta Car's high-excitation state in March 2000, the wind had a fast, dense polar wind, with higher ionization at low latitudes. Older STIS data obtained since 1998 reveal that this global stellar-wind geometry changes during eta Car's 5.5 year cycle, and may suggest that this star s spectroscopic events are shell ejections. Whether or not a companion star triggers these outbursts remains ambiguous. The most dramatic changes in the wind occur at low latitudes, while the dense polar wind remains relatively undisturbed during an event. The apparent stability of the polar wind also supports the inferred bipolar geometry. The wind geometry and its variability have critical implications for understanding the 5.5 year cycle and long-term variability, but do not provide a clear alternative to the binary hypothesis for generating eta Car s X-rays.

Smith, Nathan; Davidson, Kris; Gull, Theodore R.; Ishibashi, Kazunori; Hillier, D. John

2002-01-01

5

A COMPANION AS THE CAUSE OF LATITUDE-DEPENDENT EFFECTS IN THE WIND OF ETA CARINAE  

SciTech Connect

We analyze spatially resolved spectroscopic observations of the Eta Carinae binary system obtained with the Hubble Space Telescope/STIS. Eta Car is enshrouded by the dusty Homunculus nebula, which scatters light emitted by the central binary and provides a unique opportunity to study a massive binary system from different vantage points. We investigate the latitudinal and azimuthal dependence of H{alpha} line profiles caused by the presence of a wind-wind collision (WWC) cavity created by the companion star. Using two-dimensional radiative transfer models, we find that the wind cavity can qualitatively explain the observed line profiles around apastron. Regions of the Homunculus which scatter light that propagated through the WWC cavity show weaker or no H{alpha} absorption. Regions scattering light that propagated through a significant portion of the primary wind show stronger P Cygni absorption. Our models overestimate the H{alpha} absorption formed in the primary wind, which we attribute to photoionization by the companion, not presently included in the models. We can qualitatively explain the latitudinal changes that occur during periastron, shedding light on the nature of Eta Car's spectroscopic events. Our models support the idea that during the brief period of time around periastron when the primary wind flows unimpeded toward the observer, H{alpha} absorption occurs in directions toward the central object and Homunculus SE pole, but not toward equatorial regions close to the Weigelt blobs. We suggest that observed latitudinal and azimuthal variations are dominated by the companion star via the WWC cavity, rather than by rapid rotation of the primary star.

Groh, J. H. [Geneva Observatory, Geneva University, Chemin des Maillettes 51, CH-1290 Sauverny (Switzerland); Madura, T. I.; Weigelt, G. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Hillier, D. J. [Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260 (United States); Kruip, C. J. H., E-mail: jose.groh@unige.ch [Leiden Observatory, Leiden University, Postbus 9513, NL-2300 RA Leiden (Netherlands)

2012-11-01

6

Solar Wind Five  

NASA Technical Reports Server (NTRS)

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.

Neugebauer, M. (editor)

1983-01-01

7

Solar Wind Magnetic Fields  

NASA Technical Reports Server (NTRS)

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

Smith, E. J.

1995-01-01

8

Solar wind composition  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

9

The Solar Wind  

NSDL National Science Digital Library

This set of web pages provide an elementary introduction to the solar wind, starting with evidence from comet tails and continuing to Parker's theory of the Sun's corona and observations of the solar wind. A graphic exercise, suitable for the classroom, for tracing interplanetary magnetic field lines "dragged out" of the Sun by the solar wind is included. These pages are part of a larger site, "The Exploration of the Earth's Magnetosphere", that gives a non-mathematical introduction to the magentic properties of the sun and planets, space weather, and the motion of charged particles in magnetic fields. A Spanish translation is available.

Stern, David

2005-04-27

10

Flank solar wind interaction  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

11

Solar-wind composition experiment  

NASA Technical Reports Server (NTRS)

The Apollo program techniques for studying elemental and isotopic abundances in the solar wind are described. During Apollo 11, 12, 14 and 15 missions, aluminum foils were deployed on the lunar surface as targets for collecting solar wind ions. The foils were returned to earth, and the implanted solar wind particles were analyzed. The preliminary results showing the helium and neon concentrations are presented.

Geiss, J.; Buehler, F.; Cerutti, H.; Eberhardt, P.

1972-01-01

12

Acceleration of the solar wind  

NASA Technical Reports Server (NTRS)

Different approaches to understanding the physics of solar wind acceleration are reviewed. Particular attention is given to fundamental reasons for a supersonic wind concept; the concept of thermal conduction as the primary energy transport mechanism in the solar wind; coronal holes as the source of wind and alternative acceleration mechanisms; and the state of closure of theory and observation.

Barnes, Aaron

1992-01-01

13

Solar Wind Electrons  

Microsoft Academic Search

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

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

1975-01-01

14

Discontinuities in the solar wind  

Microsoft Academic Search

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

D. S. Colburn; C. P. Sonett

1966-01-01

15

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

E-print Network

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

Petrovay, Kristóf

16

Solar wind photoplate study  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

17

RELATED LINKS Photos: Solar & Wind  

E-print Network

RELATED LINKS Photos: Solar & Wind Power for the Home Photos: Energy Efficiency for the Home Photos and three-car garages. Business conditions at residential architecture firms are stabilizing with the entry

18

Wind in the Solar System  

ERIC Educational Resources Information Center

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

McIntosh, Gordon

2010-01-01

19

Neutral solar wind evolution during solar cycle  

NASA Technical Reports Server (NTRS)

The time dependent model of the expected fluxes of the neutral H and He components of the solar wind in the inner heliosphere is discussed. The model takes into account typical temporal evolution of the distribution of neutral interstellar gases (hydrogen and helium) in the interplanetary space due to solar cycle effects and the long term variability of the solar wind. The contribution of different charge exchange processes to the production of particular NSW element is presented. The distribution of the NSW flux is analysed with respect to the heliocentric distance and azimuthal angle from the Interstellar Wind apex. It demonstrates significant, time-dependent upwind/downwind H and He flux asymmentries. It is shown that the most pronounced modulation of the NSW flux is expected around the solar maximum epoch, when a strong decrease of the energetic H flux by two three orders of magnitude at 1 AU is predicted. The computations show that in the inner solar system (approx. 1 AU) energetic helium atoms production in the downwind region usually dominates the production of the hydrogen component This leads to the conclusion that the NSW composition at the Earth orbit strongly depends on time and the position of the observation point in reference to the apex direction.

Bzowski, M.; Rucinski, D.

1995-01-01

20

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

E-print Network

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

California at Berkeley, University of

21

Solar wind driving of magnetospheric ultra-low frequency pulsations  

Microsoft Academic Search

Two solar wind parameters in particular are thought to be responsible for the majority of solar wind-driven ULF waves. These two parameters, solar wind dynamic pressure and solar wind velocity, are studied in this work through the use of global magnetohydrodynamic (MHD) simulations of the solar wind- magnetosphere interaction. We drive the global MHD simulations with idealized solar wind input

Seth G. Claudepierre

2008-01-01

22

Solar Wind Speed Charged Dust  

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

23

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

E-print Network

The Solar Wind Helium Abundance: Variation with Wind Speed and the Solar Cycle Matthias R. Aellig Alamos National Lab., Los Alamos, NM 87545 Abstract We investigate the helium abundance in the solar wind of 1994 and early 2000 are analyzed. In agreement with similar work for previous solar cycles, we find

Richardson, John

24

Process of the supersonic solar wind formation  

NASA Astrophysics Data System (ADS)

The process of formation of the supersonic solar wind is studied on the basis of radioastronomical data. The data on radial dependence of the radio wave scaterring angle were obtained during continuous observations with the DKR-1000 radio telescope (Pushchino Radio Observatory) at distances of 4-130 Rs. It is established that the solar wind has three regimes: 1) acceleration of the subsonic wind at R < 10 Rs, 2) four stages of the solar wind acceleration by the shock waves, 3) intertial flow of the supersonic solar wind at R > 100-130 Rs.

Lotova, Natalia

25

Slow and fast solar wind acceleration near solar maximum  

Microsoft Academic Search

2-site measurements of interplanetary scintillation (IPS) provide measurements of solar wind speed in regions of the heliosphere which are otherwise inaccessible. We present results from co-ordinated observations made with the EISCAT and MERLIN facilities during 1999 and 2000, covering heliocentric distances from 7 to 80 solar radii (R) predominantly in the slow solar wind. The 1999 results are compared with

A. R. Breen; P. Thomasson; C. A. Jordan; S. J. Tappin; R. A. Fallows; A. Canals; P. J. Moran

2002-01-01

26

Comet Borrelly Slows Solar Wind  

NASA Technical Reports Server (NTRS)

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

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

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

2001-01-01

27

Observations of solar-wind helium  

NASA Technical Reports Server (NTRS)

It is pointed out that the concentration of helium in the solar wind relative to hydrogen fluctuates wildly. Under certain circumstances, the helium to hydrogen abundance ratio is strongly enhanced over probable solar values; at other times, the amount of helium in the solar wind is immeasurably small. In spite of the fact that helium is heavier than hydrogen, solar-wind helium often leaves the solar gravitational field with a higher velocity than does the hydrogen. It is thought that the mechanisms responsible for helium behavior may contain clues to unanswered questions concerning the acceleration and energy exchange processes of the entire solar wind. A brief review is given of the principal features and theories of the solar wind as a whole. In addition, measurement techniques are discussed. Emphasis throughout is on the experimental data concerning the dynamics of solar-wind helium. On the basis of coronal temperatures, it is shown that helium in the solar wind is almost always doubly ionized. It is also shown that the average abundance of helium ions in the solar wind is usually in the range of 3 to 6% by number.

Neugebauer, M.

1981-01-01

28

Wind loading on solar collectors  

SciTech Connect

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

Bhaduri, S.; Murphy, L.M.

1985-06-01

29

Solar wind interaction with the earth's magnetic field. IV - Preshock perturbation of the solar wind  

Microsoft Academic Search

Heos-1 plasma and magnetic field data are used to study the interaction of solar wind protons with protons reflected at the bow shock. The shape of this preshock perturbation region of the solar wind, created by the reflected protons, depends on the magnetic field direction along which the protons move with a velocity twice that of the solar wind. The

V. Formisano; E. Amata

1976-01-01

30

Integrated wind and solar powered desalination facility  

SciTech Connect

This design concept for a solar desalination plant couples a state of the art solar power generation system with a reverse osmosis membrane filtration system. An average throughput of 6000 m/sup 3//d is realized through operation totally independent of interconnection with the utility grid. Alternating current electric power is generated by an integrated wind and solar energy conversion system. The optimal wind/solar ratio is very dependent upon site conditions. 7 refs.

Szostak, R.M.; Agarwal, D.; Callahan, J.T.; Mohn, J.V. III

1981-01-01

31

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.

2011-05-05

32

Strahl variations with the Solar Wind properties  

NASA Astrophysics Data System (ADS)

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 the strahl component in the ambient solar wind since the launch of Cluster. The excursion of Cluster into the solar wind provides the opportunity to analyze this component of the electron velocity distribution function in a wide range of solar wind velocities and densities. The moment density and fluid velocity have been computed by spherical harmonic spectral model method. The analysis shows a correlation of the strahl density with the solar wind velocity and the time variation of the strahl density with solar cycle. This result agrees with the postulate that coronal holes are the source of this population. These preliminary results have been extended to include half solar cycle data (e.g., from 2001) to provide continuous results from solar maximum to minimum.

Nieves-Chinchilla, T.; F.-Viñas, A.; Goldstein, M. L.; Gurgiolo, C.

2009-04-01

33

Solar wind tans young asteroids  

NASA Astrophysics Data System (ADS)

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

2009-04-01

34

Direct observations of solar-wind particles  

Microsoft Academic Search

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

A. J. Hundhausen

1968-01-01

35

Solar and wind-powered irrigation systems  

Microsoft Academic Search

Five different direct solar and wind energy systems are technically feasible for powering irrigation pumps. However, with projected rates of fossil fuel costs, only two may produce significant unsubsidied energy for irrigation pumping before the turn of the century. These are photovoltaic systems with nonconcentrating collectors (providing that projected costs of manufacturing solar cells prove correct); and wind systems, especially

R. V. Enochian

1982-01-01

36

Average thermal characteristics of solar wind electrons  

NASA Technical Reports Server (NTRS)

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

Montgomery, M. D.

1972-01-01

37

Interaction of Mercury with the solar wind  

Microsoft Academic Search

The results of our 3D MHD simulation of the solar wind flow around Mercury are presented. Mercury is a planet with a highly eccentric orbit which leads to a high variability of the parameters of the solar wind impinging on the planet. Mariner 10 fly-bys detected an intrinsic magnetic field of Mercury. This intrinsic magnetic moment is responsible for the

K. Kabin; T. I. Gombosi; D. L. Dezeeuw; K. G. Powell

1998-01-01

38

The abundances of elements and isotopes in the solar wind  

NASA Technical Reports Server (NTRS)

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.

Gloeckler, George; Geiss, Johannes

1988-01-01

39

Anisotropic Scalings of solar wind turbulence  

NASA Astrophysics Data System (ADS)

Solar wind provides a natural site for studying MHD turbulence. Recently, it has been shown that the solar wind turbulence is anisotropic: the scaling law of the 2nd-order magnetic field structure function depends on the angle between the background magnetic field and the flow velocity. Furthermore, by using a local scale-dependent 3D coordinate system, Chen et al. (2012) demonstrated that the exponent of the power spectrum of the turbulent magnetic field depends on both the vector sum and difference of the two-point solar wind magnetic fields that are being examined. This anisotropy of the solar wind turbulence may depend on various variables. In this work, as an attempt to understand the property and the origin of the anisotropic scaling, we examine the structure functions of the magnetic field for several selected periods. In particular we investigate how the anisotropy depends on the solar wind type.

Xu, F.; Zhao, L.; Li, G.

2012-12-01

40

The quiescent corona and slow solar wind  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

41

Integrated wind and solar powered desalination facility  

Microsoft Academic Search

This design concept for a solar desalination plant couples a state of the art solar power generation system with a reverse osmosis membrane filtration system. An average throughput of 6000 m³\\/d is realized through operation totally independent of interconnection with the utility grid. Alternating current electric power is generated by an integrated wind and solar energy conversion system. The optimal

R. M. Szostak; D. Agarwal; J. T. Callahan; J. V. Mohn

1981-01-01

42

Global Network of Slow Solar Wind  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

43

Global network of slow solar wind  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

44

On periodicity of solar wind phenomena  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

45

The Solar Wind and Its Interaction with the Interstellar Medium  

E-print Network

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

Richardson, John

46

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

47

The solar wind in the outer heliosphere  

E-print Network

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 ...

Richardson, John D.

48

Solar wind-magnetosphere energy input functions  

Microsoft Academic Search

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

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

1985-01-01

49

The interaction of the solar wind with the interstellar medium  

NASA Technical Reports Server (NTRS)

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

Axford, W. I.

1972-01-01

50

Empirical Solar Wind Forecasting from the Chromosphere  

E-print Network

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.

Robert J. Leamon; Scott W. McIntosh

2007-01-11

51

Solar Wind's Effect on Earth  

NSDL National Science Digital Library

This video segment adapted from NASA describes solar storms and their effects on Earth. Animations of coronal mass ejections and solar cycles help explain what we know, and what we can predict, about solar activity.

Foundation, Wgbh E.

2005-12-17

52

Magnetospheric response to solar wind variations  

SciTech Connect

The time lagged response of the magnetosphere to solar wind variations has been determined using the linear prediction filtering method and 34 intervals of high time resolution IMP-8 solar wind data and auroral electrojet AL index data. The linear prediction filtering method is a powerful time series analysis technique which is utilized to produce a filter of time lagged response coefficients which estimates the most general linear relationship between magnetospheric activity and solar wind variations. This study uses the AL index to monitor the magnetosphere's response and VB/sub s/ to monitor the solar wind input. Before analysis, the median value of the AL index for each of the 34 intervals was utilized to rank the intervals according to the level of geomagnetic activity. It is found that the VB/sub s/-AL filters are composed of two response pulses peaking at time lags of 20-minutes and 60-minutes. Our interpretation associates the 20-minute pulse with activity driven directly by solar wind-magnetosphere interaction and it associates the 60-minute pulse with activity driven by the release of stored energy from the magnetotail. Thus, the filter results suggest that both the directly driven and the unloading models of magnetospheric response are important in describing the time lagged response of the magnetosphere to solar wind variations. 11 refs., 3 figs.

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

1985-04-01

53

Space Weathering Agent: Solar Wind  

NASA Astrophysics Data System (ADS)

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.

Martel, L. M. V.

2009-08-01

54

Western Wind and Solar Integration Study  

SciTech Connect

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.

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

2011-01-01

55

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

E-print Network

Differential Flow Between Solar Wind Protons and Alpha J Particles: First WIND Observations . T Flight Center, Greenbelt, Maryland w Abstract. Alpha particle and proton measurements in the solar ind particle and proton meas rements in the solar wind using the first results from the Solar o Wind Experiment

Richardson, John

56

OMNIWeb: The Ionosphere and Solar Wind  

NSDL National Science Digital Library

This educational brief provides an overview of the layers of the atmosphere, the effects of the solar wind upon them, and how these effects are mitigated by Earth's magnetic field. It also describes OMNIWeb, an internet-based data retrieval interface for obtaining datasets on solar energetic particles.

57

Genesis Solar Wind Magnesium and Iron Fluences  

Microsoft Academic Search

Fe and Mg fluences are being measured in selected Genesis collector fragments. This study is in pursuit of one of the first goals for the analysis of Genesis samples: measuring the magnitudes of first ionization potential, FIP (or first ionization time) fractionation of solar wind elemental abundances relative to the solar photosphere. Fe and Mg have FIP 7.90 and 7.64

A. J. Jurewicz; D. S. Burnett; Y. Guan; D. S. Woolum

2005-01-01

58

Solar Wind Forecasting with Coronal Holes  

Microsoft Academic Search

An empirical model for forecasting solar wind speed related geomagnetic events is presented. The model is based on the location and size of solar coronal holes determined with Kitt Peak Vacuum Telescope \\\\ion{He}{1} 1083.0 nm spectroheliograms and photospheric magnetograms. This method differs from the Wang-Sheeley model that is based on photospheric magnetograms to estimate the open field line configuration. Solar

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

2004-01-01

59

Solar Wind Forecasting with Coronal Holes  

E-print Network

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.

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

2007-01-09

60

Multiple spacecraft study of solar wind dynamics  

NASA Astrophysics Data System (ADS)

We combined simultaneous solar wind observations from five different spacecraft: Helios 1, Helios 2, IMP-8, Voyager 1 and Voyager 2, from November 1977 to February 1978 (ascending phase of solar cycle 21). During this period the large-scale dynamics of the solar wind near of the ecliptic plane was characterized by transient forward shocks (TFSs), Coronal Mass Eyections (CMEs), stream interaction regions (SIRs), and complex and variable magnetic sector structures. We characterize the solar wind streams observed by the five spacecraft. We employ maps of large-scale features to study the location of TFSs and SIRs with respect to the magnetic sector structure detected by each spacecraft. We study the geometry of the SIRs by analyzing the orientation of their Stream Interaction Regions. We study the variations of the sheath width for all the shock-CME events.

Gonzalez-Esparza, A.; Romero Hernandez, E.

2011-12-01

61

Evidence of active region imprints on the solar wind structure  

NASA Technical Reports Server (NTRS)

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

Hick, P.; Jackson, B. V.

1995-01-01

62

Solar and solar wind isotopic compositions  

Microsoft Academic Search

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

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

2004-01-01

63

Solar and solar-wind isotopic compositions  

Microsoft Academic Search

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

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

2004-01-01

64

Solar Wind Forecasting with the SOLIS-VSM  

Microsoft Academic Search

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

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

2005-01-01

65

Observed Properties of the Solar Wind  

NASA Astrophysics Data System (ADS)

The earliest measurements of the solar wind fully supported Gene Parker's theory. The wind was persistent and nearly radial, its speed was hundreds of km/s, the density was as predicted, and, on average, the interplanetary magnetic field was consistent with an Archimedian spiral. The fastest wind, with speed >700 km/s, traced back to Bartel's unipolar M regions rather than to the hotter active regions, and the highest densities could be explained by compression where the fast wind plowed into the slower wind in its path. But, even in the early data, there were mysteries, some of which are not yet completely resolved. Understanding the alpha particles has been a challenge. Their abundance is highly variable, in the fast wind their temperature is generally > 4 times the proton temperature, and, despite their greater mass, they flow away from the Sun faster than the protons. To complicate the picture further, the protons, alphas, and electrons all have complex, anisotropic distribution functions, often with double peaks. The expanding wind cools more slowly than adiabatically, suggesting a zoo of wave-particle interactions probably responsible for marginal stabilities of the particle distributions. The study of interplanetary waves and turbulence is an active field of research. Recent decades have also seen the study of ions heavier than alphas, including particles in the wind that did not originate at the Sun. Fifty years after Parker's landmark paper, solar-wind physics is still an active area of research.

Neugebauer, Marcia

2008-11-01

66

Titan interaction with the supersonic solar wind  

E-print Network

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.

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

2014-01-01

67

Laboratory Facility for Simulating Solar Wind Sails  

SciTech Connect

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.

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

68

Evidence for solar wind modulation of lightning  

NASA Astrophysics Data System (ADS)

The response of lightning rates over Europe to arrival of high speed solar wind streams at Earth is investigated using a superposed epoch analysis. Fast solar wind stream arrival is determined from modulation of the solar wind V y component, measured by the Advanced Composition Explorer spacecraft. Lightning rate changes around these event times are determined from the very low frequency arrival time difference (ATD) system of the UK Met Office. Arrival of high speed streams at Earth is found to be preceded by a decrease in total solar irradiance and an increase in sunspot number and Mg II emissions. These are consistent with the high speed stream’s source being co-located with an active region appearing on the Eastern solar limb and rotating at the 27 d period of the Sun. Arrival of the high speed stream at Earth also coincides with a small (?1%) but rapid decrease in galactic cosmic ray flux, a moderate (?6%) increase in lower energy solar energetic protons (SEPs), and a substantial, statistically significant increase in lightning rates. These changes persist for around 40 d in all three quantities. The lightning rate increase is corroborated by an increase in the total number of thunder days observed by UK Met stations, again persisting for around 40 d after the arrival of a high speed solar wind stream. This result appears to contradict earlier studies that found an anti-correlation between sunspot number and thunder days over solar cycle timescales. The increase in lightning rates and thunder days that we observe coincides with an increased flux of SEPs which, while not being detected at ground level, nevertheless penetrate the atmosphere to tropospheric altitudes. This effect could be further amplified by an increase in mean lightning stroke intensity that brings more strokes above the detection threshold of the ATD system. In order to remove any potential seasonal bias the analysis was repeated for daily solar wind triggers occurring during the summer months (June to August). Though this reduced the number of solar wind triggers to 32, the response in both lightning and thunder day data remained statistically significant. This modulation of lightning by regular and predictable solar wind events may be beneficial to medium range forecasting of hazardous weather.

Scott, C. J.; Harrison, R. G.; Owens, M. J.; Lockwood, M.; Barnard, L.

2014-05-01

69

Solar wind modulation of UK lightning  

NASA Astrophysics Data System (ADS)

The response of lightning rates in the UK to arrival of high speed solar wind streams at Earth is investigated using a superposed epoch analysis. The fast solar wind streams' arrivals are determined from modulation of the solar wind Vy component, measured by the Advanced Composition Explorer (ACE) spacecraft. Lightning rate changes around these event times are then determined from the very low frequency Arrival Time Difference (ATD) system of the UK Met Office. Arrival of high speed streams at Earth is found to be preceded by a decrease in total solar irradiance and an increase in sunspot number and Mg II emissions. These are consistent with the high speed stream's source being co-located with an active region appearing on the Eastern solar limb and rotating at the 27 day rate of the Sun. Arrival of the high speed stream at Earth also coincides with a rapid decrease in cosmic ray flux and an increase in lightning rates over the UK, persisting for around 40 days. The lightning rate increase is corroborated by an increase in the total number of thunder days observed by UK Met stations, again for around 40 days after the arrival of a high speed solar wind stream. This increase in lightning may be beneficial to medium range forecasting of hazardous weather.

Davis, Chris; Harrison, Giles; Lockwood, Mike; Owens, Mathew; Barnard, Luke

2013-04-01

70

Plasma fluctuations in the solar wind  

NASA Technical Reports Server (NTRS)

Using Ogo 5 plasma and magnetic field data, the power spectra of solar wind fluctuations are calculated over the 10 to the -3 to 10 to the -1 Hz range. It is found that the spectra calculated from flux measurements equal the density power spectra times the square of the average solar wind speed. The power spectrum relative density is of the same order of magnitude as the power spectrum of speed fluctuations relative to the Alfven speed. In cases where density and field fluctuations are inconsistent with magnetosonic waves, static inhomogeneities with a balance between electron thermal and magnetic pressures is assumed. It is also felt that a resonant proton cyclotron instability driven by the solar wind's proton thermal anisotropy may cause the observed power enhancements near 1 Hz.

Neugebauer, M.; Wu, C. S.; Huba, J. D.

1978-01-01

71

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

SciTech Connect

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.

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

72

Quiet and Disturbed Solar Wind in the New Solar Cycle  

NASA Astrophysics Data System (ADS)

Observations of the solar wind since the beginning of the STEREO mission in 2007 show the notably weak solar wind and interplanetary field described in the literature persists even in the face of the increasing activity of solar cycle 24. These conditions have produced on average low values of geoeffective parameters such as solar wind dynamic pressure and the southward component of the interplanetary field -Bz. In addition, the magnetic disturbances associated with interplanetary coronal mass ejections (ICMEs) have been primarily northward in their leading edges where their fields are compressed by their ambient solar wind interaction. This combination has generally reduced the strengths of storms produced by the ICMEs and stream interaction regions. Interestingly, the rate of CMEs in coronal images has been similar to the previous cycle which had a significantly higher sunspot number and related solar surface field. We summarize how recent conditions on the Sun have modified those that affect the Earth and planets, and the likely trends we may expect.

Luhmann, Janet G.; Jian, Lan; Galvin, Antoinette; Simunac, Kristin; Kilpua, Emilia; Russell, Christopher; Ellenburg, Michael

2012-07-01

73

Magnetosphere II: The Solar Wind Strikes Back!  

NSDL National Science Digital Library

A view of a computer-generated model of the Earth's magnetosphere. Semi-transparent surfaces represent particle density (red is high, blue is low), the silvery tube represent magnetic field lines and the yellow ribbons represent the paths of charged solar wind particles. In this particular model, the solar wind has an ambient density of 8.35 particles-cm^3. The isosurfaces are then red (>17 particles-cm^3), yellow (>12 particles-cm^3), green (>8.6 particles-cm^3) and blue (<1.0 particle-cm^3).

Bridgman, Tom; Mitchell, Horace; Sokolowsky, Eric; Spicer, Dan

2002-03-01

74

Geomagnetic activity: Dependence on solar wind parameters  

NASA Technical Reports Server (NTRS)

Current ideas about the interaction between the solar wind and the earth's magnetosphere are reviewed. The solar wind dynamic pressure as well as the influx of interplanetary magnetic field lines are both important for the generation of geomagnetic activity. The influence of the geometry of the situation as well as the variability of the interplanetary magnetic field are both found to be important factors. Semi-annual and universal time variations are discussed as well as the 22-year cycle in geomagnetic activity. All three are found to be explainable by the varying geometry of the interaction. Long term changes in geomagnetic activity are examined.

Svalgaard, L.

1977-01-01

75

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

76

Solar wind observations at STEREO: 2007 - 2011  

NASA Astrophysics Data System (ADS)

We have observed the solar wind extensively using the twin STEREO spacecraft in 2007 - 2011, covering the deep solar minimum 23/24 and the rising phase of solar cycle 24. Hundreds of large-scale solar wind structures have been surveyed, including stream interaction regions (SIRs), interplanetary CMEs (ICMEs), and interplanetary shocks. The difference in location can cause one STEREO spacecraft to encounter 1/3 more of the above structures than the other spacecraft in a single year, even of the quasi-steady SIRs. In contrast with the rising phase of cycle 23, SIRs and ICMEs have weaker field and pressure compression in this rising phase, and ICMEs drive fewer shocks. Although the majority of shocks are driven by SIRs and ICMEs, we find ~13% of shocks without clear drivers observed in situ.

Jian, L. K.; Russell, C. T.; Luhmann, J. G.; Galvin, A. B.; Simunac, K. D. C.

2013-06-01

77

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

78

CORONAL PLUMES IN THE FAST SOLAR WIND  

SciTech Connect

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 {approx}50 km s{sup -1}, 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 distances 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.

Velli, Marco [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Lionello, Roberto; Linker, Jon A.; Mikic, Zoran, E-mail: mvelli@mail.jpl.nasa.gov, E-mail: lionel@predsci.com, E-mail: linkerj@predsci.com, E-mail: mikicz@predsci.com [Predictive Science, Inc., San Diego, CA 92121-2910 (United States)

2011-07-20

79

Modeling the Slow Solar Wind during the Solar Minimum  

NASA Astrophysics Data System (ADS)

During the solar minimum, STEREO observations show that the three-dimensional structure of the solar corona can be described well by a tilted bipolar magnetic configuration. The slow solar wind is modeled using a three-fluid model that includes heavy ions such as He II and O VI. The model is initialized with a dipole magnetic field and spherically symmetric density. The resulting steady state, non-potential, and non-uniform streamer configuration calculated with this model is compared to STEREO observations of the streamer density structure. SOHO/UVCS observations are used to compare the O VI emission to model results. We discuss the unique properties of the solar wind produced in this configuration.

Ofman, L.; Kramar, M.

2010-06-01

80

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

E-print Network

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

Stern, S. Alan

81

SUBMITTED TO GRL 1 Thermal Anisotropies in the Solar Wind  

E-print Network

SUBMITTED TO GRL 1 E Thermal Anisotropies in the Solar Wind: vidence of Heating by Interstellar cyclotron instabilit s generated by newly created pickup ions and heats the thermal solar wind protons TO GRL 2 T Introduction he thermal anisotropy of the solar wind is the ratio between the temperatures p

Richardson, John

82

Apollo 11 Solar Wind Composition Experiment: First Results  

Microsoft Academic Search

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.

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

1969-01-01

83

Particle propagation channels in the solar wind  

NASA Technical Reports Server (NTRS)

The intensities of low energy solar-interplanetary electrons and ions at 1 AU occasionally change in a square wave manner. The changes may be increases or decreases and they typically have durations of from one hour to a few hours. In some cases these channels are bounded by discontinuities in the interplanetary field and the plasma properties differ from the surrounding solar wind. In one case solar flare particles were confined to a channel of width 3 x 10 to the 6th km at Earth. At the Sun this dimension extrapolates to about 12,000 km, a size comparable to small flares.

Anderson, K. A.; Dougherty, W. M.

1987-01-01

84

Triggering of substorms by solar wind discontinuities  

Microsoft Academic Search

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

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

1977-01-01

85

Corotating structure in the solar wind  

Microsoft Academic Search

The hydrodynamic equations which describe the radial solar wind expansion are linearized and specialized to treat corotating perturbations. Approximate solutions are found which are time stationary in the corotating reference frame. The solutions predict the behavior of corotating structures for a given boundary condition close to the sun. In particular, the structure resulting from the interaction of fast and slow

R. L. Carovillano; G. L. Siscoe

1969-01-01

86

Availability of Solar and Wind Generating Units  

Microsoft Academic Search

The accepted definitions of availability used for fuel-fired and nuclear generating units are not wholly appropriate for solar and wind generating units. Certain changes are suggested, and a set of availability definitions better suited to such units is proposed for discussion. These define availability of the energy resource and of weather suitable for operation separately from availability of the equipment.

Leonard D. Jaffe

1985-01-01

87

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

ERIC Educational Resources Information Center

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…

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

88

Solar and wind energy resources and prediction  

Microsoft Academic Search

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

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

2009-01-01

89

Studying Solar Wind and Magnetosphere Interactions  

NSDL National Science Digital Library

This educational brief describes the structure of Earth's magnetosphere, how it interacts with energetic particles emitted by the sun, and how it protects Earth from the effects of these particles. Short descriptions of NASA missions to study the magnetosphere, solar wind, and other particle emissions are included.

90

ISEE-C Solar Wind Plasma Experiment  

Microsoft Academic Search

Two 135° 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

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

1978-01-01

91

Dispersive shock waves in the solar wind  

Microsoft Academic Search

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

I. Ballai; E. Forgács-Dajka; A. Marcu

2007-01-01

92

Magnetopause location under extreme solar wind conditions  

Microsoft Academic Search

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

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

93

Solar wind measurements on Solar Orbiter: discovering the links between the solar wind and the atmosphere of our Sun  

NASA Astrophysics Data System (ADS)

The Solar Orbiter spacecraft, a collaborative mission between ESA and NASA, will be launched in 2017 and will include the Solar Wind Analyzer instrumentation suite. This space mission will allow for unprecedented data collection of particle characteristics near the Sun at various heliolatitudes during both the quiet and active phases of the solar cycle. The close proximity will allow for determination of the source regions on the sun for the observed events. Of particular interest will be the study of the origins of and processes related to solar energetic particles. This mission will lead to a better understanding of the Sun and the interstellar medium in our solar system. The Solar Wind Analyzer (SWA) suite is composed by a comprehensive set of sensors to characterize the Solar Wind plasma: the Electron Analyzer System to determine the properties of solar wind electrons, the Proton and Alpha Sensor to measure at high cadence the distribution functions of protons and alphas, and the Heavy Ion Sensor to analyze the minor ion components of the solar wind. As a result of the measurements SWA will take, we will be able to: Identify interplanetary shocks and characterize their spatial and temporal evolution; characterize the power spectra of density and velocity fluctuations upstream and downstream of shocks; study the heating and dissipation mechanisms at shocks at various radial distances and latitudes; and identify the mechanisms that heat thermal solar wind ions near shocks and determine the energy partition at shocks.

Livi, Stefano; Galvin, Antoinette; Kistler, Lynn; Collier, . Michael; Allegrini, Frederic; Lepri, Susan; Zurbuchen, Thomas

2012-07-01

94

Electric solar wind sail mass budget model  

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

95

Coronal magnetic fields and the solar wind  

NASA Technical Reports Server (NTRS)

Current information is presented on coronal magnetic fields as they bear on problems of the solar wind. Both steady state fields and coronal transient events are considered. A brief critique is given of the methods of calculating coronal magnetic fields including the potential (current free) models, exact solutions for the solar wind and field interaction, and source surface models. These solutions are compared with the meager quantitative observations which are available at this time. Qualitative comparisons between the shapes of calculated magnetic field lines and the forms visible in the solar corona at several recent eclipses are displayed. These suggest that: (1) coronal streamers develop above extended magnetic arcades which connect unipolar regions of opposite polarity; and (2) loops, arches, and rays in the corona correspond to preferentially filled magnetic tubes in the approximately potential field.

Newkirk, G., Jr.

1972-01-01

96

Solar wind electron temperature and density measurements for the Solar Orbiter using the thermal noise spectroscopy  

Microsoft Academic Search

The measurement of the solar wind electron temperature radial profile in the unexplored region between 1 and 45 R_s is of prime importance for understanding the solar wind acceleration. Solar Orbiter's location, combined with its ability to observe the corona in co-rotation, will furnish strong observational constraints on solar wind models. We discuss the implementation of the plasma thermal noise

M. Maksimovic; K. Issautier; M. Moncuquet; N. Meyer-Vernet; I. Zouganelis; S. D. Bale; N. Vilmer; J.-L. Bougeret

2004-01-01

97

Do solar wind dynamic pressure impulses stimulate cavity modes?  

NASA Astrophysics Data System (ADS)

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.

Kepko, E.; Angelopoulos, V.

2012-12-01

98

Corotation of an intermittent solar wind source  

NASA Technical Reports Server (NTRS)

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

Croft, T. A.

1972-01-01

99

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

E-print Network

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

Richardson, John

100

76 FR 73783 - Residential, Business, and Wind and Solar Resource Leases on Indian Land  

Federal Register 2010, 2011, 2012, 2013

...covered by Subpart E (wind energy evaluation and wind and solar resource development...to harness wind and/or solar energy to generate and supply electricity...maintenance of wind and/or solar energy resource development...

2011-11-29

101

Solar Wind Thermally Induced Magnetic Fluctuations  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

102

Bidirectional solar wind electron heat flux events  

Microsoft Academic Search

Normally the approx. >80-eV electrons which carry the solar wind electron heat flux are collimated along the interplanetary magnetic field (IMF) in the direction pointing outward away from the sun. Occasionally, however, collimated fluxes of approx. >80-eV electrons are observed traveling both parallel and antiparallel to the IMF. Here we present the results of a survey of such bidirectional electron

J. T. Gosling; D. N. Baker; S. J. Bame; W. C. Feldman; R. D. Zwickl; E. J. Smith

1987-01-01

103

Electric solar wind sail applications overview  

E-print Network

We analyse the potential of the electric solar wind sail for solar system space missions. Applications studied include fly-by missions to terrestrial planets (Venus, Mars and Phobos, Mercury) and asteroids, missions based on non-Keplerian orbits (orbits that can be maintained only by applying continuous propulsive force), one-way boosting to outer solar system, off-Lagrange point space weather forecasting and low-cost impactor probes for added science value to other missions. We also discuss the generic idea of data clippers (returning large volumes of high resolution scientific data from distant targets packed in memory chips) and possible exploitation of asteroid resources. Possible orbits were estimated by orbit calculations assuming circular and coplanar orbits for planets. Some particular challenge areas requiring further research work and related to some more ambitious mission scenarios are also identified and discussed.

Janhunen, Pekka; Envall, Jouni; Merikallio, Sini; Montesanti, Giuditta; del Amo, Jose Gonzalez; Kvell, Urmas; Noorma, Mart; Lätt, Silver

2014-01-01

104

Solar wind driving and substorm triggering  

NASA Astrophysics Data System (ADS)

We compare solar wind driving and its changes for three data sets: (1) 4861 identifications of substorm onsets from satellite global imagers (Polar UVI and IMAGE FUV); (2) a similar number of otherwise random times chosen with a similar solar wind distribution (slightly elevated driving); (3) completely random times. Multiple measures of solar wind driving were used, including interplanetary magnetic field (IMF) Bz, the Kan-Lee electric field, the Borovsky function, and d?MP/dt (all of which estimate dayside merging). Superposed epoch analysis verifies that the mean Bz has a northward turning (or at least averages less southward) starting 20 min before onset. We argue that the delay between IMF impact on the magnetopause and tail effects appearing in the ionosphere is about that long. The northward turning is not the effect of a few extreme events. The median field shows the same result, as do all other measures of solar wind driving. We compare the rate of northward turning to that observed after random times with slightly elevated driving. The subsequent reversion to mean is essentially the same between random elevations and substorms. To further verify this, we consider in detail the distribution of changes from the statistical peak (20 min prior to onset) to onset. For Bz, the mean change after onset is +0.14 nT (i.e., IMF becomes more northward), but the standard deviation is ? = 2.8 nT. Thus large changes in either direction are common. For EKL, the change is -15 nT km/s ± 830 nT km/s. Thus either a hypothesis predicting northward turnings or one predicting southward turnings would find abundant yet random confirming examples. Indeed, applying the Lyons et al. (1997) trigger criteria (excluding only the prior requirement of 22/30 min Bz < 0, which is often not valid for actual substorms) to these three sets of data shows that "northward turning triggers" occur in 23% of the random data, 24% of the actual substorms, and after 27% of the random elevations. These results strongly support the idea of Morley and Freeman (2007), that substorms require initial elevated solar wind driving, but that there is no evidence for external triggering. Finally dynamic pressure, p, and velocity, v, show no meaningful variation around onset (although p averages 10% above an 11 year mean).

Newell, Patrick T.; Liou, Kan

2011-03-01

105

Solar wind structure between 20 solar radii and the orbit of Mars  

Microsoft Academic Search

The procedure for mapping solar wind fluctuations observed at earth (1 ; AU) to other heliocentric distances under the assumption that they are corotating ; structures has been applied to Explorer 35 solar wind data to obtain solar wind ; structure between 20 Rs and the orbit of Mars. Mappings were obtained for each ; of nine lunations. Two cases

Roy R. Lewis; G. L. Siscoe

1973-01-01

106

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

NASA Astrophysics Data System (ADS)

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

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

2007-02-01

107

Variations of Strahl Properties With Fast and Slow Solar Wind  

NASA Astrophysics Data System (ADS)

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 bulk solar wind speed could provide some insight into the source, origin, and evolution of the strahl.

Nieves-Chinchilla, T.; Viñas, A. F.; Goldstein, M. L.; Gurgiolo, C.

2008-12-01

108

Variations of Strahl Properties with Fast and Slow Solar Wind  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

109

MHD Modeling of the Interaction Between the Solar Wind and Solar System Objects  

Microsoft Academic Search

Magnetohydrodynamic (MHD) models of plasma can be used to model many phenomena in the solar system. In this work we investigate the use of a general MHD solver - the Flash code - for the simulation of the interac- tion between the solar wind and solar system objects. As a test case we simulate the three-dimensional solar wind interaction with

Andreas Ekenbäck; Mats Holmström

2004-01-01

110

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

E-print Network

Solar wind electron temperature and density measurements on the Solar Orbiter with thermal noise of the plasma thermal noise analysis for the Solar Orbiter, in order to get accurate measurements of the total of their small mass and therefore large thermal speed, the solar wind electrons are expected to play a major role

California at Berkeley, University of

111

Elemental and charge state composition of the fast solar wind observed with SMS instruments on WIND  

NASA Technical Reports Server (NTRS)

The elemental composition and charge state distributions of heavy ions of the solar wind provide essential information about: (1) atom-ion separation processes in the solar atmosphere leading to the 'FIP effect' (the overabundance of low First Ionization potential (FIP) elements in the solar wind compared to the photosphere); and (2) coronal temperature profiles, as well as mechanisms which heat the corona and accelerate the solar wind. This information is required for solar wind acceleration models. The SWICS instrument on Ulysses measures for all solar wind flow conditions the relative abundance of about 8 elements and 20 charge states of the solar wind. Furthermore, the Ulysses high-latitude orbit provides an unprecedented look at the solar wind from the polar coronal holes near solar minimum conditions. The MASS instrument on the WIND spacecraft is a high-mass resolution solar wind ion mass spectrometer that will provide routinely not only the abundances and charge state of all elements easily measured with SWICS, but also of N, Mg, S. The MASS sensor was fully operational at the end of 1994 and has sampled the in-ecliptic solar wind composition in both the slow and the corotating fast streams. This unique combination of SWICS on Ulysses and MASS on WIND allows us to view for the first time the solar wind from two regions of the large coronal hole. Observations with SWICS in the coronal hole wind: (1) indicate that the FIP effect is small; and (2) allow us determine the altitude of the maximum in the electron temperature profile, and indicate a maximum temperature of approximately 1.5 MK. New results from the SMS instruments on Wind will be compared with results from SWICS on Ulysses.

Gloeckler, G.; Galvin, A. B.; Ipavich, F. M.; Hamilton, D. C.; Bochsler, P.; Geiss, J.; Fisk, L. A.; Wilken, B.

1995-01-01

112

Magnetospheric cavity modes driven by solar wind dynamic pressure fluctuations  

NASA Astrophysics Data System (ADS)

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 introduce monochromatic ULF fluctuations in the upstream solar wind dynamic pressure. In the fifth simulation, we introduce a continuum of ULF frequencies in the upstream solar wind dynamic pressure fluctuations. In this numerical experiment, the idealized nature of the solar wind driving conditions allows us to study the magnetospheric response to only a fluctuating upstream dynamic pressure, while holding all other solar wind driving parameters constant. The simulation results suggest that ULF fluctuations in the solar wind dynamic pressure can drive magnetospheric ULF pulsations in the electric and magnetic fields on the dayside. Moreover, the simulation results suggest that when the driving frequency of the solar wind dynamic pressure fluctuations matches one of the natural frequencies of the magnetosphere, magnetospheric cavity modes can be energized.

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

2009-07-01

113

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

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

Webb, David F.

114

Elemental composition variations in the solar wind: Comparisons between Ulysses and ACE within different solar wind regimes  

NASA Astrophysics Data System (ADS)

The elemental composition of the solar wind is likely established at the base of the corona, a conclusion based on the observed dependence of solar wind abundances on the first ionization potential (FIP) of the elements. Although the plasma conditions within the ecliptic solar wind are highly variable, the elemental composition is less so, and is an indicator of the nature of the solar source. In particular, coronal hole (CH, fast) solar wind tends to have less of a FIP enhancement of the low -FIP elements (e.g., Fe, Mg, Si) than interstream (IS, slow) solar wind. The elemental composition of coronal mass ejections (CMEs) is more variable, but tends to be similar to IS composition. The question we address here is how much does the average composition of the different solar wind regimes vary over the course of the solar cycle and between solar cycles. For the most recent solar cycle, which included the unusually deep and prolonged solar minimum (2006 - 2010) Lepri et al. (2013) have shown measurable drifts in the elemental composition within solar wind regimes using data from the Advanced Composition Explorer (ACE) Solar Wind Ion Composition Spectrometer (SWICS). In contrast, von Steiger and Zurbuchen (2011) have shown using Ulysses SWIC data that the composition of the very fast polar coronal hole flow has remained constant. Here, we extend the Lepri et al. ecliptic analysis to include data from Ulysses, which allows us to expand the analysis to the previous solar cycle (1990 - 2001), as well as check consistency with their recent solar cycle results. (Note that although Ulysses was nominally a polar mission, it spent considerable time at low latitudes as well.) A major driver for this investigation is the Genesis Mission solar wind sample analysis. Namely, was the solar wind sampled by Genesis between late 2001 and early 2004 typical of the solar wind over longer time scales, and hence a representative sample of the long-term solar wind, or was it somehow unique? Our initial findings show that the low-FIP composition measured by ACE/SWICS during the Genesis collection period was, within systematic error, in agreement with that measured by Ulysses (when it was at latitudes < |20°|). Specifically, the measured CH, IS, and CME Fe/O abundances differed between the ACE and Ulysses by 17%, 6.9% and +17%, respectively. The overall solar wind Fe/O ratio differed by only -3.6%. We will give further details on this comparison, and discuss variations in elemental composition over the course of the solar cycle and between cycles.

Pilleri, P.; Reisenfeld, D. B.; Wiens, R. C.

2013-12-01

115

Solar wind acceleration in coronal holes. [High speed solar wind streams  

Microsoft Academic Search

Past attempts to explain the large solar wind velocities in high speed streams by theoretical models of the expansion have invoked either extended nonthermal heating of the corona, heat flux inhibition, or direct addition of momentum to the expanding coronal plasma. Several workers have shown that inhibiting the heat flux at low coronal densities is probably not adequate to explain

Kopp

1978-01-01

116

Solar and Wind Technologies for Hydrogen Production: Report to Congress Solar and Wind Technologies  

E-print Network

.........................5 1.4 Potential Capacity for Hydrogen Production from Conventional Electrolysis Using Wind and Solar ..................................................................................................8 1.6 Effect of Electricity Price on the Cost of Hydrogen Produced by Electrolysis ............................................................................................18 Section 3: Thermochemical (Water Splitting) Hydrogen Production .........................19 3

117

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

Microsoft Academic Search

The measurement of the solar wind electron temperature in the unexplored region between 1 and 45Rs is of prime importance for understanding the solar wind acceleration. Solar Orbiter’s location, combined with the fact that the spacecraft will nearly co-rotate with the sun on some portions of its orbit, will furnish observations placing constraints on solar wind models. We discuss the

M. Maksimovic; K. Issautier; N. Meyer-Vernet; C. Perche; M. Moncuquet; I. Zouganelis; S. D. Bale; N. Vilmer; J.-L. Bougeret

2005-01-01

118

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

E-print Network

15/06/2005 Solar Wind 11/SOHO 16 1 Radial Dependence of Solar Energetic Particle Events M;15/06/2005 Solar Wind 11/SOHO 16 10 A perihelion worth of particles 40 days data between 0.3 and 0.5 AU (May.-B. Kallenrode #12;15/06/2005 Solar Wind 11/SOHO 16 2 Outline No discussion about composition and charge states

Kallenrode, May-Britt

119

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

120

Electric conductivity of plasma in solar wind  

NASA Technical Reports Server (NTRS)

One of the most important parameters in MHD description of the solar wind is the electric conductivity of plasma. There exist now two quite different approaches to the evaluation of this parameter. In the first one a value of conductivity taken from the most elaborated current theory of plasma should be used in calculations. The second one deals with the empirical, phenomenological value of conductivity. E.g.: configuration of interplanetary magnetic field, stretched by the expanding corona, depends on the magnitude of electrical conductivity of plasma in the solar wind. Knowing the main empirical features of the field configuration, one may estimate the apparent phenomenological value of resistance. The estimations show that the electrical conductivity should be approximately 10(exp 13) times smaller than that calculated by Spitzer. It must be noted that the empirical value should be treated with caution. Due to the method of its obtaining it may be used only for 'large-scale' description of slow processes like coronal expansion. It cannot be valid for 'quick' processes, changing the state of plasma, like collisions with obstacles, e.g., planets and vehicles. The second approach is well known in large-scale planetary hydrodynamics, stemming from the ideas of phenomenological thermodynamics. It could formulate real problems which should be solved by modern plasma physics, oriented to be adequate for complicated processes in space.

Chertkov, A. D.

1995-01-01

121

Solar Wind Spectrometer on Lunar Surface  

NASA Technical Reports Server (NTRS)

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.

1969-01-01

122

Solar wind velocity and temperature in the outer heliosphere  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

123

LUNAR AND PLANETARY TAILS IN THE SOLAR WIND  

Microsoft Academic Search

The concept that comets form tails in the solar wind is reasonably well estab- lished, but a suggestion that the moon and the inner planets also cast long shadows in the solar wind has met with objection, mainly on statistical grounds. A lunar or planetary tail would from its nature be difficult to detect, but it is more likely to

E. G. Bowen

1964-01-01

124

Comparative Study of MHD Modeling of the Background Solar Wind  

NASA Astrophysics Data System (ADS)

Knowledge about the background solar wind plays a crucial role in the framework of space-weather forecasting. In-situ measurements of the background solar wind are only available for a few points in the heliosphere where spacecraft are located, therefore we have to rely on heliospheric models to derive the distribution of solar-wind parameters in interplanetary space. We test the performance of different solar-wind models, namely Magnetohydrodynamic Algorithm outside a Sphere/ENLIL (MAS/ENLIL), Wang-Sheeley-Arge/ENLIL (WSA/ENLIL), and MAS/MAS, by comparing model results with in-situ measurements from spacecraft located at 1 AU distance to the Sun (ACE, Wind). To exclude the influence of interplanetary coronal mass ejections (ICMEs), we chose the year 2007 as a time period with low solar activity for our comparison. We found that the general structure of the background solar wind is well reproduced by all models. The best model results were obtained for the parameter solar-wind speed. However, the predicted arrival times of high-speed solar-wind streams have typical uncertainties of the order of about one day. Comparison of model runs with synoptic magnetic maps from different observatories revealed that the choice of the synoptic map significantly affects the model performance.

Gressl, C.; Veronig, A. M.; Temmer, M.; Odstr?il, D.; Linker, J. A.; Miki?, Z.; Riley, P.

2014-05-01

125

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

Microsoft Academic Search

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

W. I. Axford

1962-01-01

126

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

Microsoft Academic Search

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

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

1991-01-01

127

Venus Ionosphere and Solar Wind Interaction  

NASA Astrophysics Data System (ADS)

Venus Express, which was inserted into orbit in mid-2006, has added significantly to the knowledge gained from Pioneer Venus from 1978 to 1992. This observational database interpreted in terms of modern multi-fluid codes and hybrid simulations has deepened our understanding of Earth’s very different twin sister planet. Furthermore, the very different orbits of VEX and PVO has allowed the more complete mapping of the volume of space around the planet. Now the bow shock has been probed over its full surface, the ionosphere mapped everywhere, and the tail studied from the ionosphere to 12 Venus radii. Some unexpected discoveries have been made. The exospheric hydrogen at Venus, unlike that at Mars, does not produce ion-cyclotron waves, perhaps because the stronger gravity of Venus produces a smaller geocorona. The solar wind interaction drapes the magnetic field around the planet, and a strong layer of magnetic field builds up at low altitudes. While the layer does not appear to penetrate into the dayside atmosphere (perhaps diffusing only slowly through the low atmosphere), it does appear to dip into the atmosphere at night. Surprisingly, over the poles, this layer is most strongly seen when the IMF BY component has a positive Y-component in Venus-Solar-Orbital coordinates. Multi-fluid simulations show that this result is consistent with the pressure of significant ion densities of ions with quite different mass which causes magnetic polarity control of the ion flow over the terminators. Reconnection is found in the tail close to the planet, and the structure of the outer tail found by PVO is confirmed to exist in the inner tail by VEX. When combined, the VEX and PVO Data provide a very comprehensive picture of the physics of the solar wind interaction with the ionosphere of Venus.

Russell, C. T.; Luhmann, Janet G.; Ma, Yingjuan; Zhang, Tielong; Villarreal, M.

128

Magnetohydrodynamic modeling of the solar wind in the outer heliosphere  

SciTech Connect

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.

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

129

Solar wind iron charge states preceding a driver plasma  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

130

Where do we stand in understanding fast solar wind acceleration?  

NASA Astrophysics Data System (ADS)

Ulysses and SOHO/UVCS were instrumental in confirming the origin of fast solar wind streams in solar coronal holes. In this paper I will try to assess where our understanding of fast solar wind acceleration really stands, illustrating new observations and the most recent models involving reflection-driven Alfvenic turbulence, Alfven waves and compressible interactions, and coronal plumes and microstream shear. Since Alfvenic turbulence is often considered "exotic" I will also try to give an understandable, yet precise, description of the large scale interaction of Alfven waves in the solar wind, including turbulence phenomenologies. While models predicated on turbulence come the closest to describing the fast solar wind correctly, a number of issues, from the precise dissipation mechanisms, to the relative roles of helium and minor ions, to the formation and role of the ubiquitous electron strahl in the fast wind still remain far from resolution.

Velli, Marco

2012-07-01

131

OBSERVATION OF FLUX-TUBE CROSSINGS IN THE SOLAR WIND  

SciTech Connect

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.

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

132

The Western Wind and Solar Integration Study Phase 2  

SciTech Connect

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

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

2013-09-01

133

Solar Wind Composition: First Results from SOHO and Future Expectations  

NASA Astrophysics Data System (ADS)

The SOHO payload includes three experiments designed to make "in situ" particle measurements of the solar wind and solar energetic particles (CELIAS, D. Hovestadt PI; COSTEP, H. Kunow PI; ERNE, J. Torsti PI). The solar wind measurements that are the focus of this talk are primarily provided by the CELIAS CTOF and MTOF sensors. (CELIAS/STOF and COSTEP-ERNE measure solar and interplanetary suprathermal and energetic particle populations.) CELIAS/CTOF measures solar wind heavy ion elemental and charge state abundances, information which is used (for example) in identifying the type of solar wind flow and the ionization processes in the corona where the solar wind charge states become "frozen-in". CELIAS/MTOF provides heavy ion elemental and isotopic abundances that are important (for example) in the study of fractionation factors in coronal abundances (as in the so-called "FIP-effect") for the rarer elements not resolvable in conventional solar wind composition instruments, and in determining the isotopic make-up of the solar corona. MTOF is, by far, the most powerful solar wind mass spectrometer flown to date, and already has new science to report at the time of this writing. This happenstance is due to a combination of (1) advanced technology in obtaining high mass resolution for ions at solar wind energies, and (2) increased statistics. The excellent counting statistics are largely due to continuous solar wind monitoring (with its position at L1, ``the Sun never sets on SOHO''), and the continuous sampling of the solar wind by the 3-axis stabilized spacecraft further enhanced by MTOF's novel, never previously flown deflection system that encompasses a very large dynamic range. As might be expected, this unique opportunity has allowed MTOF to identify a number of elements for the first time in the solar wind (e.g., P, Ti, Cr and Ni). A rich assortment of solar wind isotopes have been identified for the first time, many of which (e.g., Fe 54 and 56; Ni 58,60,62) have not been detected previously even in solar energetic particle populations nor remotely using spectroscopic techniques.

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

1996-05-01

134

Wind\\/solar energy investigation, a feasibility study  

Microsoft Academic Search

The question of utilizing the wind and sun to provide the energy required by an average home for space heating, air conditioning, and a hot water supply was considered. Energy requirements were compared with the daily availability of wind and solar energy and the storage needed to reconcile the two was determined. Preliminary design procedures are shown for wind and

G. H. Stickney

1975-01-01

135

Mass loading of the solar wind by a sungrazing comet  

NASA Astrophysics Data System (ADS)

Collisionless mass loading was suggested by Biermann et al. (1967) for describing interactions between the solar wind and cometary atmospheres. Recent observations have led to an increased interest in coronal mass loading due to sungrazing comets and collisional debris of sunward migrating interplanetary dust particles. In a previous paper, we presented a 3-D MHD model of the solar corona based on the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme code which includes the interaction of dust with the solar wind. We have shown the impact on the solar wind from abrupt mass loading in the coronal region. We apply the model to a sungrazing cometary source, using ejected dust dynamics to generate tail-shaped mass-loading regions. Results help predict the effects on the solar wind acceleration and composition due to sungrazing comets, such as Comet C/2011 W3 (Lovejoy). We show how these effects may be detected by the upcoming Solar Probe Plus Mission.

Rasca, A. P.; Oran, R.; Horányi, M.

2014-08-01

136

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

Microsoft Academic Search

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

Wei Zhou

2008-01-01

137

Solar wind and the motion of dust grains  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the action of solar wind on an arbitrarily shaped interplanetary dust particle. The final relativistically covariant equation of motion of the particle also contains the change of the particle's mass. The non-radial solar wind velocity vector is also included. The covariant equation of motion reduces to the Poynting-Robertson effect in the limiting case when a spherical particle is treated, when the speed of the incident solar wind corpuscles tends to the speed of light and when the corpuscles spread radially from the Sun. The results of quantum mechanics have to be incorporated into the physical considerations, in order to obtain the limiting case. If the solar wind affects the motion of a spherical interplanetary dust particle, then ?. Here, p'in and p'out are the incoming and outgoing radiation momenta (per unit time), respectively, measured in the proper frame of reference of the particle, and ? and ? are the solar wind pressure and the total scattering cross-sections, respectively. An analytical solution of the derived equation of motion yields a qualitative behaviour consistent with numerical calculations. This also holds if we consider a decrease of the particle's mass. Using numerical integration of the derived equation of motion, we confirm our analytical result that the non-radial solar wind (with a constant value of angle between the radial direction and the direction of the solar wind velocity) causes outspiralling of the dust particle from the Sun for large values of the particle's semimajor axis. The non-radial solar wind also increases the time the particle spirals towards the Sun. If we consider the periodical variability of the solar wind with the solar cycle, then there are resonances between the particle's orbital period and the period of the solar cycle.

Kla?ka, J.; Petržala, J.; Pástor, P.; Kómar, L.

2012-04-01

138

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.

139

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

Microsoft Academic Search

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

M. A. Elhadidy; S. M. Shaahid

2000-01-01

140

Solar wind-plasma interaction - The AMPTE solar wind plasma releases  

NASA Technical Reports Server (NTRS)

A summary is given of the most important effects observed during the 3 AMPTE solar wind ion releases. Some of these effects may be of relevance in comparable astrophysical situations when large amounts of matter are injected into an ambient magnetized plasma streaming with a velocity much larger than the sonic and Alfvenic Mach numbers. For detailed presentations the reader is referred to the original publications listed in the References.

Bauer, O. H.; Baumjohann, W.; Foeppl, H.; Haerendel, G.; Haeusler, B.

1986-01-01

141

Asymmetric Electron Distributions in the Solar Wind  

NASA Astrophysics Data System (ADS)

A plausible mechanism responsible for producing asymmetric electron velocity distribution functions in the solar wind is investigated by means of one-dimensional electrostatic particle-in-cell (PIC) simulation. A recent paper suggests that the variation in the ion-to-electron temperature ratio influences the nonlinear wave-particle dynamics such that it results in the formation of asymmetric distributions. The present PIC code simulation largely confirms this finding, but quantitative differences between the weak turbulence formalism and the present PIC simulation are also found, suggesting the limitation of the analytical method. The inter-relationship between the asymmetric electron distribution and the ion-to-electron temperature ratio may be a new useful concept for the observation.

Rha, Kicheol; Ryu, Chang-Mo; Yoon, Peter H.

2013-09-01

142

Genesis Solar Wind Array Collector Cataloging Status  

NASA Technical Reports Server (NTRS)

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.

Burkett, P.J.; Rodriguez, M.C.; Calaway, M.C.; Allton, J.H.

2009-01-01

143

Magnetic holes in the solar wind  

NASA Technical Reports Server (NTRS)

An analysis of high-resolution magnetic field measurements from the Goddard Space Flight Center magnetometer on Explorer 43 showed that low magnetic field intensities (less than 1 gamma) in the solar wind at 1 AU occur as distinct depressions, or 'holes', in otherwise nearly average conditions. These magnetic holes are new kinetic scale phenomena, having a characteristic dimension of the order of 20,000 km. They occurred at a rate of 1.5/d in the 18-day interval (March 18 to April 6, 1971) that was considered. Most magnetic holes are characterized by both a depression in /B/ and a change in the magnetic field direction, and some of these are possibly the result of magnetic merging. However, in other cases the direction, does not change; such holes are not due to merging but might be a diamagnetic effect due to localized plasma inhomogeneities.

Turner, J. M.; Burlaga, L. F.; Ness, N. F.; Lemaire, J. F.

1977-01-01

144

Magnetic clouds in the solar wind  

NASA Technical Reports Server (NTRS)

Two interplanetary magnetic clouds, characterized by anomalous magnetic field directions and unusually high magnetic field strengths with a scale of the order of 0.25 AU, are identified and described. As the clouds moved past a spacecraft located in the solar wind near Earth, the magnetic field direction changed by rotating approximately 180 deg nearly parallel to a plane which was essentially perpendicular to the ecliptic. The configuration of the magnetic field in the clouds might be that of a tightly wound cylindrical helix or a series of closed circular loops. One of the magnetic clouds was in a cold stream preceded by a shock, and it caused both a geomagnetic storm and a depression in the galactic cosmic ray intensity. No stream, geomagnetic storm, or large cosmic ray decrease was associated with the other magnetic cloud.

Burlaga, L. F.; Klein, L.

1980-01-01

145

COMPOSITION OF THE SOLAR CORONA, SOLAR WIND, AND SOLAR ENERGETIC PARTICLES  

SciTech Connect

Along with temperature and density, the elemental abundance is a basic parameter required by astronomers to understand and model any physical system. The abundances of the solar corona are known to differ from those of the solar photosphere via a mechanism related to the first ionization potential of the element, but the normalization of these values with respect to hydrogen is challenging. Here, we show that the values used by solar physicists for over a decade and currently referred to as the 'coronal abundances' do not agree with the data themselves. As a result, recent analysis and interpretation of solar data involving coronal abundances may need to be revised. We use observations from coronal spectroscopy, the solar wind, and solar energetic particles as well as the latest abundances of the solar photosphere to establish a new set of abundances that reflect our current understanding of the coronal plasma.

Schmelz, J. T. [Physics Department, University of Memphis, Memphis, TN 38152 (United States); Reames, D. V. [IPST, University of Maryland, College Park, MD 20742 (United States); Von Steiger, R. [ISSI, Hallerstrasse 6, 3012 Bern (Switzerland); Basu, S., E-mail: jschmelz@memphis.edu [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)

2012-08-10

146

Turbulent heating of the corona and solar wind: the heliospheric  

E-print Network

Turbulent heating of the corona and solar wind: the heliospheric dark energy problem Stuart D. Bale, hot magnetized plasma (Cranmer et al., 2008) An important measurement: perpendicular heating F corona solar corona 1919 eclipse photo, Sobral 1571, Caron #12;The solar corona Coronal structure often

147

Residual Energy Spectrum of Solar Wind Turbulence  

NASA Astrophysics Data System (ADS)

It has long been known that the energy in velocity and magnetic field fluctuations in the solar wind is not in equipartition. In this paper, we present an analysis of 5 yr of Wind data at 1 AU to investigate the reason for this. The residual energy (difference between energy in velocity and magnetic field fluctuations) was calculated using both the standard magnetohydrodynamic (MHD) normalization for the magnetic field and a kinetic version, which includes temperature anisotropies and drifts between particle species. It was found that with the kinetic normalization, the fluctuations are closer to equipartition, with a mean normalized residual energy of ?r = -0.19 and mean Alfvén ratio of r A = 0.71. The spectrum of residual energy, in the kinetic normalization, was found to be steeper than both the velocity and magnetic field spectra, consistent with some recent MHD turbulence predictions and numerical simulations, having a spectral index close to -1.9. The local properties of residual energy and cross helicity were also investigated, showing that globally balanced intervals with small residual energy contain local patches of larger imbalance and larger residual energy at all scales, as expected for nonlinear turbulent interactions.

Chen, C. H. K.; Bale, S. D.; Salem, C. S.; Maruca, B. A.

2013-06-01

148

RESIDUAL ENERGY SPECTRUM OF SOLAR WIND TURBULENCE  

SciTech Connect

It has long been known that the energy in velocity and magnetic field fluctuations in the solar wind is not in equipartition. In this paper, we present an analysis of 5 yr of Wind data at 1 AU to investigate the reason for this. The residual energy (difference between energy in velocity and magnetic field fluctuations) was calculated using both the standard magnetohydrodynamic (MHD) normalization for the magnetic field and a kinetic version, which includes temperature anisotropies and drifts between particle species. It was found that with the kinetic normalization, the fluctuations are closer to equipartition, with a mean normalized residual energy of {sigma}{sub r} = -0.19 and mean Alfven ratio of r{sub A} = 0.71. The spectrum of residual energy, in the kinetic normalization, was found to be steeper than both the velocity and magnetic field spectra, consistent with some recent MHD turbulence predictions and numerical simulations, having a spectral index close to -1.9. The local properties of residual energy and cross helicity were also investigated, showing that globally balanced intervals with small residual energy contain local patches of larger imbalance and larger residual energy at all scales, as expected for nonlinear turbulent interactions.

Chen, C. H. K.; Bale, S. D.; Salem, C. S.; Maruca, B. A., E-mail: chen@ssl.berkeley.edu [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2013-06-20

149

Comparison of Coronal Streamer Properties to Solar Wind Models For The Last Two Solar Cycle Minima  

NASA Astrophysics Data System (ADS)

We characterize the physical properties of two coronal streamers during Earth/Ulysses quadrature configurations for the previous two solar minimum periods. Comparisons between coronal remote-sensing observations and in situ measurements of solar wind plasma properties are being used to characterize the origin of slow wind streams. In order to investigate slow solar wind heating and acceleration, we compare the measurements with predictions from MHD models. We aim to use the empirical measurements to distinguish between different proposed physical processes for the slow solar wind. This work is supported by NASA grant NNX10AQ58G to the Smithsonian Astrophysical Observatory.

Miralles, Mari Paz; Landi, E.; Cranmer, S. R.; Raymond, J. C.; Cohen, O.; Oran, R.

2013-07-01

150

Coronal Heating and the Solar Wind Acceleration  

NASA Astrophysics Data System (ADS)

The twisting magnetic field as the DC energy injection will produce charge separation and consequently an electric field parallel to the magnetic field. Accelerated beam electrons (a few times thermal velocity) due to this electric filed will be stopped by classical collisions with ambient electrons and ions. The beam electrons, 10-3 of the bulk electrons, do not create electric currents due to the back streaming bulk electrons. Hence it is not the normal or anomalous Joule heating, but a co-spatial frictional heating, and yet bulk heating. The heating rate is the kinetic energy density of beams multiplied by the classical collision frequency, and is about 10-4 erg cm-3 s-1. It successfully reproduces observations of quiet and active regions, including the RTV scaling law. In the open field, the damping length of this Alfvénic twist is 0.4 solar radii. This is appropriate to produce slow and high-speed solar winds. Ion-cyclotron waves may be excited due to supra-thermal beams.

Hirayama, T.

151

Wind\\/WAVES observations of high-frequency plasma waves in solar wind reconnection exhausts  

Microsoft Academic Search

(1) This paper studies high-frequency plasma waves during 28 encounters of the Wind spacecraft with solar wind reconnection exhausts. We use measurements by the Thermal Noise Receiver (TNR) and Time Domain Sampler (TDS) experiments on Wind\\/WAVES to survey characteristics of electron plasma waves and the most common regions where they are found. TNR spectrograms showed intense emission bursts ? 4

K. E. J. Huttunen; S. D. Bale; T. D. Phan; M. Davis; J. T. Gosling

2007-01-01

152

Flow Sources of The Solar Wind Stream Structieres  

NASA Astrophysics Data System (ADS)

The large-scale stream structure of the solar wind flow was studied at the main acceler- ation area of 10 to 40 solar radii from the Sun. Three independent sets of experimental data were used: radio astronomy observations of radio wave scattering on near-solar plasmas (large radio telescopes of the P.N.Lebedev Physical Institute were used); mor- phology of the WLC as revealed by the SOHO optical solar corona observations; solar magnetic field strength and configuration computed using the Wilcox Solar Observa- tory data. Experimental data of 1997-1998 years on the position of the transition, tran- sonic region of the solar wind flow were used as a parameter reflecting the intensity of the solar plasmas acceleration process. Correlation studies of these data combined with the magnetic field strength at the solar corona level revealed several types of the solar wind streams differing in the final result, the velocity at large distances from the Sun. Besides of the well-known flows stemming from the polar coronal holes, high-speed streams were observed arising in lateral areas of the streamer structures in contrast to the main body of the streamers, being a known source of the slow solar wind. The slowest streams arise at areas of mixed magnetic field structure compris- ing both open and closed (loop-like) filed lines. In the white-light corona images this shows extensive areas of bright amorphous luminosity.

Lotova, N. A.; Obridko, V. N.; Vladimirskii, K. V.

153

Iron charge states in the solar wind as measured by SMS on Wind  

NASA Technical Reports Server (NTRS)

The Wind spacecraft was launched in November 1994. In the first half of 1995 it was in the interplanetary medium upstream of the Earth. The Solar Wind and Suprathermal Ion Composition Experiment (SMS) on Wind consists of three sensors, the Solar Wind Ion Composition Spectrometer (SWICS), the Suprathermal Ion Composition Spectrometer (STICS), and the high mass resolution spectrometer (MASS). All three instruments utilize electrostatic deflection combined with time-of-flight measurement. The data from these three sensors allows the determination of the ionic composition of the solar wind in a variety of solar wind conditions over a large energy/charge range (0.5 to 230 keV/e). We have examined the Wind database for time periods conducive to observing solar wind iron. With the high mass resolution of the MASS spectrometer (M/Delta-M greater than 100) iron is easily identified while the electrostatic deflection provides information concerning the mass/charge distribution. We present here the relative abundance of iron charge states in the solar wind near 1 AU.

Galvin, A. B.; Cohen, C. M. S.; Ipavich, F. M.; Gloeckler, G.; Hamilton, D. C.; Chotoo, K.; Balsiger, H.; Sheldon, R.

1995-01-01

154

The solar wind interaction with unmagnetized planets - A tutorial  

NASA Technical Reports Server (NTRS)

The interaction of the solar wind with the Venus ionosphere induces currents which can substantially exclude the solar wind and IMF from the dayside ionosphere beneath the 'ionopause', where ionosphere thermal pressure equals incident solar wind dynamic pressure. The field then diffuses through the ionopause with increasing speed at decreasing altitudes, and is weakest in the subpolar region. Once within the ionopause, the magnetic field is redistributed by ionospheric convection, and then decays at low altitudes via collisional dissipation of the associated currents. The maximum ionospheric field magnitudes observed, of about 150 nT, furnish magnetic pressures exceeding the ionospheric thermal pressure by a factor of about 3.

Luhmann, J. G.

1990-01-01

155

MEASUREMENTS OF RAPID DENSITY FLUCTUATIONS IN THE SOLAR WIND  

SciTech Connect

The power spectrum of density fluctuations in the solar wind is inferred by tracking small timescale changes in the electron plasma frequency during periods of strong Langmuir wave activity. STEREO electric field waveform data are used to produce time profiles of plasma density from which the density power spectrum is derived. The power spectra obtained by this method extend the observed frequency range by an order of magnitude while remaining consistent with previous results near a few Hertz. Density power spectral indices are found to be organized by the angle between the local magnetic field and the solar wind direction, indicating significant anisotropy in solar wind high-frequency density turbulence.

Malaspina, D. M.; Ergun, R. E. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 (United States); Kellogg, P. J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Bale, S. D., E-mail: David.Malaspina@colorado.ed [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2010-03-01

156

3D Hall MHD Modeling of Solar Wind Plasma Spectra  

E-print Network

We present fully self consistent 3D simulations of compressible Hall MHD plasma that describe spectral features relevant to the solar wind plasma. We find that a $k^{-7/3}$ spectrum sets in for the fluctuations that are smaller than ion gyro radius. We further investigate scale dependent anisotropy led by nonlinear processes relevant to the solar wind plasma. Our work is important particularly in understanding the role of wave and nonlinear cascades in the evolution of the solar wind, structure formation at the largest scales.

Shaikh, Dastgeer

2009-01-01

157

Estimates of solar wind heating inside 0.3 AU  

NASA Technical Reports Server (NTRS)

Helios 1 proton temperature data have been normalized in order to determine a base temperature-velocity curve at 0.3 AU and to provide quantitative estimates on the close-in heating at different solar wind velocities. The results suggest that the slope of the solar wind temperature gradients for high-speed streams inside 0.3 AU is about half of that found beyond it. The very-low-speed wind is shown to expand adiabatically all the way out. It is also found that intermediate speed winds have enhanced heating rates in proportion to their velocities.

Freeman, John W.

1988-01-01

158

Solar wind driving of magnetospheric ultra-low frequency pulsations  

NASA Astrophysics Data System (ADS)

Two solar wind parameters in particular are thought to be responsible for the majority of solar wind-driven ULF waves. These two parameters, solar wind dynamic pressure and solar wind velocity, are studied in this work through the use of global magnetohydrodynamic (MHD) simulations of the solar wind- magnetosphere interaction. We drive the global MHD simulations with idealized solar wind input conditions, chosen to mimic each of the above mechanisms. This allows us to study, in isolation, both of the solar wind parameters and to compare and contrast their effectiveness in the generation of magnetospheric ULF waves. Moreover, the global, three-dimensional nature of the MHD simulations allows us to fully characterize the spectral properties and global distribution of the ULF waves generated. These wave properties are known from a theoretical standpoint to be important for the interaction of ULF waves with radiation belt electrons. From these considerations, we are able to quantify the effect that the simulated ULF waves could have on radiation belt electrons, and thus, how the solar wind ultimately couples its energy into the radiation belts. Though this is the primary goal of our work, these investigations have uncovered two magnetospheric phenomenon, the MHD Kelvin-Helmholtz instability and magnetospheric cavity modes, that have never before been studied in the realistic magnetospheric configuration provided by global MHD simulations. The MHD Kelvin-Helmholtz instability has long been predicted to occur at the boundary interface between the solar wind and the magnetosphere and is often invoked as an explanation for various magnetospheric phenomenon. For example, several theoretical studies have suggested that the Kelvin-Helmholtz instability at the magnetospheric boundary drives magnetospheric field-line resonances, resonant oscillations of geomagnetic field lines analogous to standing waves on a string. In addition, the nonlinear evolution of the MHD Kelvin-Helmholtz instability leads to large-scale (several times the size of the Earth) vortices in the plasma flow. A number of studies have suggested that these vortical structures are responsible for the entry of solar wind plasma into the magnetosphere. This is an important process in the magnetosphere as solar wind plasma ultimately fuels geomagnetic storms and the auroras. Though the magnetospheric Kelvin-Helmholtz interaction has been studied from a theoretical standpoint in simple flow configurations for many years, it has received little attention in modern, global MHD simulations. Moreover, while many studies have presented surface wave observations that can be easily explained in terms of the Kelvin-Helmholtz theory, others argue that the observations can just as easily be explained by fluctuating upstream solar wind plasma parameters. We circumvent these ambiguities by driving global MHD simulations with idealized solar wind input conditions, where all of the upstream solar wind plasma parameters are held constant. Thus, any surface waves generated at the magnetospheric boundary cannot be due to fluctuations in the upstream solar wind. We show that the Kelvin-Helmholtz instability is excited at both edges of the magnetospheric boundary layer and over a wide range of solar wind speeds (400-800 km/s). The results presented in the first half of this work are the first comprehensive study of the MHD Kelvin-Helmholtz instability in a realistic magnetospheric configuration. Magnetospheric cavity modes have been studied for many years, both theoretically and through simple numerical simulations. The concept of magnetospheric cavity modes is physically quite appealing; however, such oscillations have proved elusive in magnetospheric observations. Moreover, global MHD simulations have yet to reproduce cavity mode oscillations, further calling into question their existence. The results presented in the second half of this work show the excitation of magnetospheric cavity modes in global MHD simulations of the solar wind-magnetosphere interaction. These resonant cavity mod

Claudepierre, Seth G.

159

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

Microsoft Academic Search

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

J. P. Reichling; F. A. Kulacki

2008-01-01

160

Role of solar wind dynamic pressure in driving ionospheric Joule heating  

Microsoft Academic Search

We investigate the role of the solar wind dynamic pressure on the ionospheric dynamics both observationally and using a global MHD simulation. Using ACE solar wind observations we carry out a statistical superposed epoch analysis, in which we determine the ionospheric response, as characterized by the AE index, to solar wind pressure pulses identified from the ACE solar wind data.

M. Palmroth; T. I. Pulkkinen; P. Janhunen; D. J. McComas; C. W. Smith; H. E. J. Koskinen

2004-01-01

161

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

Microsoft Academic Search

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

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

162

Interpretation of 3He variations in the solar wind  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

163

Solar wind-plasma interaction: The AMPTE solar wind plasma releases  

NASA Technical Reports Server (NTRS)

In situ measurements during AMPTE solar wind ion releases are described. The creation of a diamagnetic cavity, compression and draping of magnetic field lines, recoil of the entire artificial comet, and ion beam and tail formation are discussed. The wave measurements were used to determine the time variation of the plasma density from the measurement of the electron plasma frequency and to determine the state of cloud expansion and cavity formation. Features found include absence of strong turbulence and anomalous diffusion in the cavity boundary, and the appearance of very intense shock-like emission in front of the plasma clouds. The first effect suggests partially unknowm processes leading to magnetic field penetration into the region of the clouds. The direct observation of the interaction processes between the fast streaming solar wind plasma and the expanding cloud plasma of the Li and artificial comet releases may have relevance to astrophysical situations as, for instance, encountered in solar flares, interstellar clouds, or during accretion of matter onto compact objects.

1986-01-01

164

Transient flows of the solar wind associated with small-scale solar activity in solar minimum  

NASA Astrophysics Data System (ADS)

The data obtained by the modern high sensitive EUV-XUV telescopes and photometers such as CORONAS-Photon/TESIS and SPHINX, STEREO/EUVI, PROBA2/SWAP, SDO/AIA provide good possibilities for studying small-scale solar activity (SSA), which is supposed to play an important role in heating of the corona and producing transient flows of the solar wind. During the recent unusually weak solar minimum, a large number of SSA events, such as week solar flares, small CMEs and CME-like flows were observed and recorded in the databases of flares (STEREO, SWAP, SPHINX) and CMEs (LASCO, CACTUS). On the other hand, the solar wind data obtained in this period by ACE, Wind, STEREO contain signatures of transient ICME-like structures which have shorter duration (<10h), weaker magnetic field strength (<10 nT) and lower proton temperature than usual ICMEs. To verify the assumption that ICME-like transients may be associated with the SSA events we investigated the number of weak flares of C-class and lower detected by SPHINX in 2009 and STEREO/EUVI in 2010. The flares were classified on temperature and emission measure using the diagnostic means of SPHINX and Hinode/EIS and were confronted with the parameters of the solar wind (velocity, density, ion composition and temperature, magnetic field, pitch angle distribution of the suprathermal electrons). The outflows of plasma associated with the flares were identified by their coronal signatures - CMEs (only in few cases) and dimmings. It was found that the mean parameters of the solar wind projected to the source surface for the times of the studied flares were typical for the ICME-like transients. The results support the suggestion that weak flares can be indicators of sources of transient plasma flows contributing to the slow solar wind at solar minimum, although these flows may be too weak to be considered as separate CMEs and ICMEs. The research leading to these results has received funding from the European Union’s Seventh Programme for Research, Technological Development and Demonstration under Grant Agreement “eHeroes” (project n° 284461, www.eheroes.eu).

Slemzin, Vladimir; Veselovsky, Igor; Kuzin, Sergey; Gburek, Szymon; Ulyanov, Artyom; Kirichenko, Alexey; Shugay, Yulia; Goryaev, Farid

165

Genesis Solar Wind Sample Curation: A Progress Report  

NASA Technical Reports Server (NTRS)

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.

Allton, Judith H.; Calaway, M. J.; Rodriquez, M. C.; Hittle, J. D.; Wentworth, S. J.; Stansbery, E. K.; McNamara, K. M.

2006-01-01

166

Kinematic Treatment of CME Evolution in the Solar Wind.  

National Technical Information Service (NTIS)

We present a kinematic study of the evolution of coronal mass ejections (CMEs) in the solar wind. Specifically, we consider the effects of: (1) spherical expansion; and (2) uniform expansion due to pressure gradients between the Interplanetary CME (ICME) ...

P. Riley, N. U. Crooker

2004-01-01

167

Mass dragged from Mars's atmosphere by the solar wind  

NASA Astrophysics Data System (ADS)

In the past Mars had a denser atmosphere, but it lacks a magnetic field to protect the ionosphere and exosphere from the solar wind. A model describing the loss of atmosphere by the erosion of the solar wind in geologic time is presented. Recent results shows that the Martian dynamo existed in Early and Middle Noachian. Then solar wind erosion would have started at the end of Middle Noachian or the beginning of Late Noachian. With this assumption the amount of volatiles dragged by the solar wind, if the chronology developed by Neukum and Wise is correct, is in the range of 0.472 to 1.89 Terrestrial Atmospheric Masses (TAM). If the chronology developed by Hartmann et al. is correct, the loss remains in the range of 0.0624 to 0.25 TAM.

Durand-Manterola, H. J.

2003-12-01

168

Integrating Multiple Approaches to Solving Solar Wind Turbulence Problems (Invited)  

NASA Astrophysics Data System (ADS)

The ultimate understanding of the solar wind turbulence must explain the physical process and their connection at all scales ranging from the largest down to electron kinetic scales. This is a daunting task and as a result a more piecemeal approach to the problem has been followed. For example, the role of each wave has been explored in isolation and in simulations with scales limited to those of the underlying waves. In this talk, we present several issues with this approach and offer an alternative with an eye towards more realistic simulations of solar wind turbulence. The main simulation techniques used have been MHD, Hall MHD, hybrid, fully kinetic, and gyrokinetic. We examine the limitations of each approach and their viability for studies of solar wind turbulence. Finally, the effect of initial conditions on the resulting turbulence and their comparison with solar wind are demonstrated through several kinetic simulations.

Karimabadi, H.; Roytershteyn, V.

2013-12-01

169

A solar-wind model including proton thermal anisotropy.  

NASA Technical Reports Server (NTRS)

A relatively simple model is proposed to study the magnetohydrodynamic expansion of the solar wind. The interplanetary space is divided into an 'inner region' and an 'outer region.' In the inner region the solar wind is one-fluid and thermally isotropic. The solar-wind protons are assumed to be completely collisionless in the outer region. Thus the solar wind is two-fluid in nature, and the protons are thermally anisotropic in the outer region. It is assumed that throughout the interplanetary space electrons are thermally isotropic due to collisions or other processes. The electron heat flux is supposed to obey the well-known relationships that the flux is parallel to the magnetic-field vector and is directly proportional to the spatial derivative of the electron temperature.

Whang, Y. C.

1972-01-01

170

Western Wind and Solar Integration Study: Phase 2 (Presentation)  

SciTech Connect

This presentation summarizes the scope and results of the Western Wind and Solar Integration Study Phase 2, which examined operational impacts of high penetrations of variable renewable generation in the West.

Lew, D.; Brinkman, G.; Ibanez, E.; Lefton, S.; Kumar, N.; Venkataraman, S.; Jordan, G.

2013-09-01

171

Western Wind and Solar Integration Study Phase 2 (Fact Sheet)  

SciTech Connect

This is one-page, two-sided fact sheet presents high-level summary results of the Western Wind and Solar Integration Study Phase 2, which examined operational impacts of high penetrations of variable renewable generation in the West.

Not Available

2013-09-01

172

Solar Wind and Magnetosphere Interaction Lab: A Cereal Analogy  

NSDL National Science Digital Library

This open-ended laboratory activity is useful in demonstrating how solar wind particles are deflected by the Earth's magnetosphere and how charged particles are aligned within it. After this lesson, students should be able to discuss and describe the components of solar wind particles, explain why the magnetosphere and ionosphere protect the Earth, and explain how moving particles behave (and align) in a magnetic field. Additional links lead to background material, standards, and assessment.

173

Mixed solar wind originating from coronal regions of different temperatures  

NASA Technical Reports Server (NTRS)

Ionization states of elements in the solar wind are often used to determine thermal gradients in the lower corona. This method is based on the assumption, that in the beginning, solar wind material has a homogeneous temperature determining the original charge state of elements. Features in M/Q-spectra which might appear if the above assumption is violated are investigated and compared with observational evidence.

Bochsler, P.

1983-01-01

174

Moving an asteroid with electric solar wind sail  

Microsoft Academic Search

The electric solar wind sail (E-Sail) is a new propulsion method for interplanetary travel which was invented in 2006 and is currently under development. The E-Sail uses charged tethers to extract momentum from the solar wind particles to obtain propulsive thrust. According to current estimates, the E-Sail is 2-3 orders of magnitude better than traditional propulsion methods (chemical rockets and

Sini Merikallio; P. Janhunen

2010-01-01

175

Calculation of solar wind flows about terrestrial planets  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

176

Interplanetary stream magnetism: Kinematic effects. [solar magnetic fields and wind  

NASA Technical Reports Server (NTRS)

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.

Burlaga, L. F.; Barouch, E.

1974-01-01

177

Quiet solar wind insights from STEREO multipoint observations  

NASA Astrophysics Data System (ADS)

The primary mission phase of the STEREO mission began in late January 2007 and includes solar minimum conditions as we transit into solar cycle 24. This interval has been a very quiet time, with few in-situ transient events. The solar features include long-lived polar and isolated coronal holes. The solar wind has been dominated by a recurring series of high and slow speed streams, with an occasional interplanetary shock associated with corotating/stream interaction regions. In this talk, we present an overview of recent insights on the quiet solar wind from the STEREO perspective, including plasma, magnetic field and composition insitu parameters (PLASTIC and IMPACT) and associated solar sources seen in remote images (SECCHI). Similarities and variations as observed by the two spacecraft over longitude, latitude and time are discussed. The quiet solar wind is interesting in its own right, and also provides a perspective as we begin the rise to solar maximum when STEREO will begin encountering "disturbed" solar wind associated with coronal mass ejections.

Galvin, Antoinette

178

Potential for Development of Solar and Wind Resource in Bhutan  

SciTech Connect

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.

Gilman, P.; Cowlin, S.; Heimiller, D.

2009-09-01

179

Prediction of solar energetic particle event histories using real-time particle and solar wind measurements  

NASA Technical Reports Server (NTRS)

The comparatively well-ordered magnetic structure in the solar corona during the decline of Solar Cycle 20 revealed a characteristic dependence of solar energetic particle injection upon heliographic longitude. When analyzed using solar wind mapping of the large scale interplanetary magnetic field line connection from the corona to the Earth, particle fluxes display an approximately exponential dependence on heliographic longitude. Since variations in the solar wind velocity (and hence the coronal connection longitude) can severely distort the simple coronal injection profile, the use of real-time solar wind velocity measurements can be of great aid in predicting the decay of solar particle events. Although such exponential injection profiles are commonplace during 1973-1975, they have also been identified earlier in Solar Cycle 20, and hence this structure may be present during the rise and maximum of the cycle, but somewhat obscured by greater temporal variations in particle injection.

Roelof, E. C.; Gold, R. E.

1978-01-01

180

Sputtering by the Solar Wind: Effects of Variable Composition  

NASA Technical Reports Server (NTRS)

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.

Killen, R. M.; Arrell, W. M.; Sarantos, M.; Delory, G. T.

2011-01-01

181

Western Wind and Solar Integration Study Phase 2: Preprint  

SciTech Connect

The Western Wind and Solar Integration Study (WWSIS) investigates the impacts of high penetrations of wind and solar power into the Western Interconnection of the United States. WWSIS2 builds on the Phase 1 study but with far greater refinement in the level of data inputs and production simulation. It considers the differences between wind and solar power on systems operations. It considers mitigation options to accommodate wind and solar when full costs of wear-and-tear and full impacts of emissions rates are taken into account. It determines wear-and-tear costs and emissions impacts. New data sets were created for WWSIS2, and WWSIS1 data sets were refined to improve realism of plant output and forecasts. Four scenarios were defined for WWSIS2 that examine the differences between wind and solar and penetration level. Transmission was built out to bring resources to load. Statistical analysis was conducted to investigate wind and solar impacts at timescales ranging from seasonal down to 5 minutes.

Lew, D.; Brinkman, G.; Ibanez, E.; Hodge, B.-M.; King, J.

2012-09-01

182

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

NASA Astrophysics Data System (ADS)

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 mechanisms heating the corona that continue to elude us. As the only accessible space plasma laboratory, we must continue its exploration in search of the processes that impact the Earth's environment and govern the evolution of stars and their planetary systems.

Habbal, Shadia Rifia; Woo, Richard

2004-08-01

183

Dissipation of Turbulence in the Solar Wind  

NASA Technical Reports Server (NTRS)

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.

Goldstein, Melvyn L.

2010-01-01

184

Laboratory Investigations of Solar Wind Sputtering  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

185

Interaction of Comets and the Solar Wind  

NASA Technical Reports Server (NTRS)

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.

Wagner, William (Technical Monitor); Raymond, John C.

2003-01-01

186

Interaction of Comets and the Solar Wind  

NASA Technical Reports Server (NTRS)

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.

Wagner, William (Technical Monitor); Raymond, John C.

2004-01-01

187

Coronal hole structure and the high speed solar wind  

NASA Technical Reports Server (NTRS)

The basic physical processes which are important in the acceleration of high speed wind from coronal holes are reviewed. The early works of Birkeland and Parker are discussed. The extension of Parker's work is included. It is shown that the greatest area of uncertainty is that of coronal heating. It is demonstrated that in modeling solar wind acceleration, it is important to carry out a study on the chromosphere-corona-wind system analysis.

Holzer, Thomas E.; Leer, Egil

1997-01-01

188

Time-dependent solar wind flows in the heliosheath  

NASA Astrophysics Data System (ADS)

Recent observations on Voyager 1 and 2 spacecraft show complex and very different solar wind flows in the heliosheath region. Voyager 2 has been observing constant radial flows (Richardson and Wang 2013). At the beginning of 2011 Voyager 1 entered a region with zero and even negative radial velocity of the plasma flow (Krimigis et al. 2011). Since mid 2012 Voyager 1 continues observing a new region in the heliosheath with fast changing of intensities of anomalous and galactic cosmic rays. These puzzling observational data motivate us to explore different physical effects at the edges of the heliosphere in the models. In order to separate spatial from temporal effects the investigation of time-dependent effects are crucial. In this work we focus on time-dependent effects of the 11-year solar cycle. We use a global MHD multi-fluid model of interaction of the solar wind with the local interstellar medium with time-dependent boundary conditions for the supersonic solar wind. Realistic boundary conditions (plasma density and velocity) at 1 AU for the plasma were obtained from the measurements of Ly-alpha intensities on SOHO/SWAN, OMNI data and interplanetary scintillations data. We present effects of realistic variations of the solar wind dynamic pressure on the solar wind flow in the heliosheath and in the vicinity of the heliopause. Comparing the results of time-dependent model along the Voyager 1 and 2 trajectory with observational data we describe effects of solar cycle on the flows that Voyager measures.

Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.

2013-05-01

189

Solar wind iron charge states preceding a driver plasma  

SciTech Connect

During September 28 and 29, 1978, the ISEE 3 spacraft observed several distinct types of high-speed solar wind flows when a coronal hole--associated high-speed stream was followed by two interplanetary shocks, one of which was driven by flare ejecta contained in a ''magnetic cloud'' or interplanetary ''plasmoid.'' Using the University of Maryland/Max-Planck-Institut ultralow energy charge analyzer (ULECA) on ISEE 3, we present solar wind Fe and Si/S charge state and Fe density measurements for the different plasma regimes associated with the flare-related shock and combine these measurements with the Los Alamos National Laboratory proton observations to obtain iron/hydrogen density ratios and iron/hydrogen velocity differences. We place special emphasis on the postshock shell of turbulent and compressed ambient solar wind and interplanetary magnetic fields constituting the ''sheath region'' preceding the driver plasma. It is generally expected that the abundance ratios and charge states of the solar wind ions in the driver plasma and the sheath remain distinct, reflecting their different origins in the solar corona. However, while the Fe/H abundance ratios observed in the sheath are consistent with the preshock solar wind values (and a factor of 2 to 6 times less than the values obtained in the driver plasma), the iron charge states observed in the sheath appear to indicate a transition between the lower charge states observed in the ambient (coronal hole associated) solar wind and the higher charge states observed in the driver plasma. These results may reflect X ray ionization of the solar wind plasma near the flare site, although other explanations are possible. copyright American Geophysical Union 1987

Galvin, A.B.; Ipavich, F.M.; Gloeckler, G.; Hovestadt, D.; Bame, S.J.; Klecker, B.; Scholer, M.; Tsurutani, B.T.

1987-11-01

190

Solar wind control of the earth's electric field  

Microsoft Academic Search

The sun-weather problem is placed within an electrical framework subject to experimental investigation. An explanation is suggested for how solar variability modulates the earth's electric field. The solar wind velocity is inversely correlated with the electrical potential of the ionosphere, a measure of the overall intensity of the earth's fair-weather atmospheric electric field. In seeking a physical cause of this

R. Markson; M. Muir

1980-01-01

191

Corotating solar wind streams and recurrent geomagnetic activity: A review  

Microsoft Academic Search

Solar wind fast streams emanating from solar coronal holes cause recurrent, moderate intensity geomagnetic activity at Earth. Intense magnetic field regions called Corotating Interaction Regions or CIRs are created by the interaction of fast streams with upstream slow streams. Because of the highly oscillatory nature of the GSM magnetic field z component within CIRs, the resultant magnetic storms are typically

Bruce T. Tsurutani; Walter D. Gonzalez; Alicia L. C. Gonzalez; Fernando L. Guarnieri; Nat Gopalswamy; Manuel Grande; Yohsuke Kamide; Yoshiya Kasahara; Gang Lu; Ian Mann; Robert McPherron; Finn Soraas; Vytenis Vasyliunas

2006-01-01

192

Global auroral response to a solar wind pressure pulse  

Microsoft Academic Search

A global intensification of the aurora was observed by the Ultraviolet Imager on the NASA Polar spacecraft in conjunction with the arrival of the sheath from a solar coronal mass ejection. The aurora was first observed to brighten on the dayside and then the intensification progressed rapidly toward the nightside. During this time the IMP-8 spacecraft in the solar wind

M. Brittnacher; M. Wilber; M. Fillingim; D. Chua; G. Parks; J. Spann; G. Germany

2000-01-01

193

A survey of the polar cap density based on Cluster EFW probe measurements: Solar wind and solar irradiation dependence  

E-print Network

a survey of the polar cap densities and the response to changes in the solar irradiation, solar wind on Cluster EFW probe measurements: Solar wind and solar irradiation dependence, J. Geophys. Res., 117, A01216 is strongly influenced by solar activity, in particular irradiance in the extreme ultraviolet range (EUV

Bergen, Universitetet i

194

Velocity Distributions and Proton Beam Production in the Solar Wind  

SciTech Connect

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.

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

2010-03-25

195

Velocity shear layers in solar winds affect Earth's magnetosphere  

NASA Astrophysics Data System (ADS)

Human society is increasingly reliant on technology that can be disrupted by space weather. For instance, geomagnetic storms can cause high-latitude air fights to be rerouted, costing as much as $100,000 per fight; induce errors of up to 46 meters in GPS systems; and affect satellites and the International Space Station. Space weather is determined by how the solar wind, a stream of hot plasma from the Sun, interacts with Earth's magnetic field. In studying space weather, scientists have largely neglected the fact that the solar wind contains layers of very strong velocity shear. Scientists understand very little about how these wind shears affect space weather.

Bhattacharya, Atreyee

2012-09-01

196

Some remarks on waves in the solar wind  

NASA Astrophysics Data System (ADS)

Waves are significant to the solar wind in two ways as modifiers of the particle distribution functions, and as diagnostics. In addition, the solar wind serves as an important laboratory for the study of plasma wave processes, as it is possible to make detailed measurements of phenomena which are too small to be easily measured by laboratory sized sensors. There are two areas where waves (we include discontinuities under this heading) must make important modifications of the distribution functions: in accelerating the alpha particles to higher speeds than the protons (Marsch et al.) and in accelerating the solar wind itself. A third area is possibly in maintaining the relative isotropy of the solar wind ion distribution in the solar wind rest frame. As the solar wind is nearly collisionless, the ions should conserve magnetic moment in rushing out from the sun, and therefore Tperp/B should be relatively constant, but it is obviously not. This has not received much attention. The waves, both electromagnetic and electrostatic, which are pan of the solar Type 111 burst phenomenon, have been extensively studied as examples of nonlinear plasma phenomena, and also used as remote sensors to trace the solar magnetic field. The observations made by Ulysses show that the field can be traced in this way out to perhaps a little more than an A.U., but then the electromagnetic pan of the type 111 burst fades out. Nevertheless, sometimes Langmuir waves appear at Ulysses at an appropriate extrapolated time. This seems to support the picture in which the electromagnetic waves at the fundamental plasma frequency are trapped in density fluctuations. Langmuir waves in the solar wind are usually in quasi-thermal equilibrium quasi because the solar wind itself is not isothermal. The Observatory of Paris group (Steinberg. Meyer-Vernet, Hoang) has exploited this with an experiment on WIND which is capable of providing density and temperature on a faster time scale than hitherto. Recently it has been found that Langmuir waves are associated with magnetic holes. This may help to elucidate the nature of magnetic holes. Nonlinear processes are important in the transformation of wave energy to panicle energy. Some recent examples from WIND data will be shown.

Kellogg, Paul J.

1995-06-01

197

Shuffling foot points and magnetohydrodynamic discontinuities in the solar wind  

NASA Technical Reports Server (NTRS)

ISEE three-field and plasma data are used to investigate the frequency of occurrence of isolated, large-amplitude rotational (RD) and tangential (TD) discontinuities in different types of solar wind flow. It is found that there are relatively more TDs in solar wind that originates in closed field regions and is ejected into interplanetary space by coronal transients than in the solar wind that originates in open field regions. The speed of the wind from open field regions is approximately linearly related to the number of RDs per hour; such a relation does not exist for the wind associated with coronal mass ejections. These results are consistent with the hypothesis that the convection-driven shuffling of magnetic foot points at the solar surface leads to TDs, magnetic reconnection, and heating of the corona on closed field lines, while in the open field regions the disturbances created by the shuffling are carried off by waves which contribute to the acceleration of the solar wind.

Neugebauer, M.; Alexander, C. J.

1991-01-01

198

Super Storm Dependence upon Solar-Wind-Magnetosphere Coupling  

NASA Astrophysics Data System (ADS)

Statistical relationships were explored between super geomagnetic storms (Dst < -200 nT) and solar wind parameters. We consider coupling parameters such as the Akasofu epsilon parameter, total energy input into the magnetosphere, Kan and Lee electric field, solar wind electric field, and the IMF components. Correlations between super storms and the solar wind help us understand how energy is transferred into the magnetosphere. Data was obtained using the OMNIWeb data center. OMNIWeb complies magnetic field and plasma measurements from a suite of spacecraft (ACE, Geotail, Wind, IMP-8, ISEE3) and Dst measurements from the NOAA and Kyoto data hubs. Results show a strong correlation (r > 0.8) between the solar wind electric field and IMF components as a function of Dst. Moderate correlations (r > 0.6) exist upon the Akasofu epsilon parameter, total energy input, and Kan and Lee electric field with Dst. The total energy input during a super storm is about a factor of two greater than a normal storm and about a factor of six greater in comparison to the solar wind electric field. Results also suggest a natural separation between normal storms and super storms, which suggest different energization mechanisms. Practical applications of this study relate to radiation belt dynamics which threaten our spacecraft and astronauts.

Clark, George; Goldstein, Jerry; Jahn, Joerg-Micha

2010-10-01

199

Shear flow induced wave couplings in the solar wind  

SciTech Connect

A sheared background flow in a plasma induces coupling between different MHD wave modes, resulting in their mutual transformations with corresponding energy redistributing between the modes. In this way, the energy can be transfered from one wave mode to the other, but energy can also be added to or extracted from the background flow. In the present paper it is investigated whether the wave coupling and energy transfer mechanisms can operate under solar wind conditions. It is shown that this is indeed the case. Hence, the long-period waves observed in the solar wind at r > 0.3 AU might be generated by much faster periodic oscillations in the photosphere of the Sun. Other possible consequences for observable beat phenomena in the wind and the acceleration of the solar wind particles are also discussed.

Poedts, S. [KULeuven, Heverlee (Belgium). Centre for Plasma Astrophysics; Rogava, A.D. [Tbilisi State Univ. (Georgia). Dept. of Physics]|[International Centre for Theoretical Physics, Trieste (Italy); Mahajan, S.M. [Univ. of Texas, Austin, TX (United States). Institute for Fusion Studies]|[International Centre for Theoretical Physics, Trieste (Italy)

1998-01-01

200

Coronal Streamers and Their Associated Solar Wind Streams  

NASA Astrophysics Data System (ADS)

We use the EUV spectrometers aboard SOHO and Hinode and white-light coronagraphs to characterize the physical properties of coronal streamers during Earth/Ulysses quadrature configurations for the previous two solar minimum periods. In addition, comparisons between coronal observations and in situ measurements of solar wind plasma properties are being used to further characterize the origins of slow wind streams. In order to investigate slow solar wind heating and acceleration, we also compare with predictions from three-dimensional MHD models. We aim to use the empirical measurements to distinguish between different proposed physical processes for slow wind acceleration (e.g., waves/turbulence versus reconnection). This work is supported by NASA grant NNX10AQ58G to the Smithsonian Astrophysical Observatory.

Miralles, M. P.; Landi, E.; Cranmer, S. R.; Cohen, O.; Raymond, J. C.

2012-12-01

201

Solar wind entry into the magnetosphere under northward IMF conditions  

NASA Astrophysics Data System (ADS)

The state of the plasma sheet in the magnetosphere is usually observed to be hot (1-10 keV) and tenuous (~0.1 cm -3 ). However, sometimes part of it is observed to be colder (< 1 keV) and denser (~1 cm -3 ), and the plasma flow is almost stagnant. Much higher density (~10 cm -3 ) plasma material (superdense plasma sheet) is also sometimes observed near the geosynchronous orbit. The cold dense plasma sheet (CDPS) is usually observed after a period of northward interplanetary magnetic field (IMF), which is also a necessary condition for the formation of a superdense plasma sheet (SDPS). Since the CDPS is generally absent of a cold O + component, and the ionospheric outflow is strong only under southward IMF condition, the source of the CDPS is thought to be the solar wind. Usually, solar wind plasma and energy entry into the magnetosphere is considered to occur mainly during the southward IMF condition through reconnection processes that first occur at the dayside magnetopause and then in the magnetotail. However, the formation of CDPS suggests that there are also certain processes that let solar wind enter the magnetosphere when the IMF is northward. The purpose of this dissertation study is to find out the mechanism that transports solar wind plasma into the magnetosphere under northward IMF conditions, and thus to find out the mechanism of the formation of CDPS and SDPS. To study the solar wind entry mechanism, I use global simulations of the magnetosphere in conjunction with the analysis of observation data. The model used here is the Open Global Geospace Circulation Model (OpenGGCM), which is a magnetosphere MHD model with a stretched grid that has higher grid resolution near the Earth. The simulation is driven by the upstream solar wind input. I run simulations for several CDPS events to validate the model by comparing the simulation results with observations. I then establish that the double high- latitude reconnection process is the dominant process that leads to the entry of solar wind plasma under northward IMF conditions, and that it is sufficient to form the CDPS. With the successful simulation of CDPS events, I continue to study a SDPS event in detail using simulation and observations from a series of spacecraft. I find that the southward IMF following a long period of northward IMF condition compresses the preexisting CDPS, and sets off the near-tail reconnection that causes the compressed CDPS to be pushed and accelerated toward the Earth and form the SDPS near the geosynchronous orbit. I further systematically study how the solar wind plasma enters the magnetosphere due to double high-latitude reconnection for various solar wind, northward IMF and geomagnetic dipole conditions. I trace flow paths from the solar wind and study the variation of the magnetic field line topology along the flow paths. I find that there is an entry window through which the solar wind plasma can enter the magnetosphere as a result of double high-latitude reconnection under northward IMF conditions. I show how the entry window depends on solar wind, IMF and geomagnetic dipole parameters. With the entry window, I estimate the solar wind plasma entry rate for various conditions. I find that the entry rate under northward IMF conditions is of the order of 10 26 to 10 27 particles per second. I also estimate the conditions at which solar wind plasma entry is most efficient.

Li, Wenhui

202

SOLAR WIND HEAVY IONS OVER SOLAR CYCLE 23: ACE/SWICS MEASUREMENTS  

SciTech Connect

Solar wind plasma and compositional properties reflect the physical properties of the corona and its evolution over time. Studies comparing the previous solar minimum with the most recent, unusual solar minimum indicate that significant environmental changes are occurring globally on the Sun. For example, the magnetic field decreased 30% between the last two solar minima, and the ionic charge states of O have been reported to change toward lower values in the fast wind. In this work, we systematically and comprehensively analyze the compositional changes of the solar wind during cycle 23 from 2000 to 2010 while the Sun moved from solar maximum to solar minimum. We find a systematic change of C, O, Si, and Fe ionic charge states toward lower ionization distributions. We also discuss long-term changes in elemental abundances and show that there is a {approx}50% decrease of heavy ion abundances (He, C, O, Si, and Fe) relative to H as the Sun went from solar maximum to solar minimum. During this time, the relative abundances in the slow wind remain organized by their first ionization potential. We discuss these results and their implications for models of the evolution of the solar atmosphere, and for the identification of the fast and slow wind themselves.

Lepri, S. T.; Landi, E.; Zurbuchen, T. H. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, TC 2210 Ann Arbor, MI 48109 (United States)

2013-05-01

203

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

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

204

Elemental composition in the slow solar wind measured with the MASS instrument on WIND  

NASA Technical Reports Server (NTRS)

The MASS instrument on WIND contains the first isochronous time-offlight spectrometer to be flown in the solar wind. The first spectra obtained with this instrument has demonstrated its capability to measure the abundances of several high-and low-FIP elements in the solar wind. The derivation of these abundances requires a careful calibration of the charge exchange efficiencies of the relevant ions in carbon foils. These efficiencies and the corresponding instrument functions have been determined in extensive calibration campaigns at different institutions. We present first and preliminary results obtained in slow solar wind streams and we compare these results with those obtained from previous investigations of solar wind abundances and of coronal abundances as derived from Solar Energetic Particles. Recent models of the FIP related fractionation effect predict a depletion of a factor of typically 4 to 5 for high-FIP elements (He, N, O, Ne, Ar, etc.) relative to low-FIP elements (Mg, Fe, Si, etc.). We also compare our results with the detailed predictions of the different models and we discuss the resulting evidence to validate or to invalidate different physical scenarios explaining the feeding and the acceleration of slow stream solar wind.

Bochsler, P.; Gonin, M.; Sheldon, R. B.; Zurbuchen, Th.; Gloeckler, G.; Galvin, A. B.; Hovestadt, D.

1995-01-01

205

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

Microsoft Academic Search

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

Jared B. Garrison; Michael E. Webber

2011-01-01

206

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

E-print Network

headings: acceleration of particles -- methods: numerical -- solar wind -- stars: winds, outflows -- Sun: First, the particle VDFs might not be Maxwellians at the base of the solar wind. Second, the particleA TRANSONIC COLLISIONLESS MODEL OF THE SOLAR WIND I. Zouganelis,1 M. Maksimovic,1 N. Meyer-Vernet,1

Meyer-Vernet, Nicole

207

A demonstrative study for the wind and solar hybrid power system  

Microsoft Academic Search

In March 1995, a small scale wind and solar hybrid power system was installed at Ashikaga Institute of Technology. Until now, the authors have acquired the data of the output of the hybrid power plant along with wind speed, wind direction, and the solar radiation, in order to demonstrate a complementary relationship between solar energy and wind energy.After nine months

Yukihiro Kimura; Yoshihiro Onai; Izumi Ushiyama

1996-01-01

208

Wind\\/WAVES observations of high-frequency plasma waves in solar wind reconnection exhausts  

Microsoft Academic Search

This paper studies high-frequency plasma waves during 28 encounters of the Wind spacecraft with solar wind reconnection exhausts. We use measurements by the Thermal Noise Receiver (TNR) and Time Domain Sampler (TDS) experiments on Wind\\/WAVES to survey characteristics of electron plasma waves and the most common regions where they are found. TNR spectrograms showed intense emission bursts ?4 kHz (corresponding

K. E. J. Huttunen; S. D. Bale; T. D. Phan; M. Davis; J. T. Gosling

2007-01-01

209

Solar wind H-3 and C-14 abundances and solar surface processes. [in lunar soil  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

210

Shock Acceleration of the Energetic Particle Background in the Solar Wind David T. Sodaitis  

E-print Network

the Lee (1983) theory. 1. Introduction to the Solar Wind The solar wind consists of a stream of ions of the gas pressure differential between the sun's corona and interplanetary space, which exerts a force on planet Earth, the solar wind is an important topic for study because it is strongly influenced by solar

211

Non-adiabatic expansion of low-temperature solar wind radial temperature gradients  

Microsoft Academic Search

Temperatures in the solar plasma at 1 AU have been observed to drop, on the average, to one third (for electrons) and one tenth (for protons) of the value for the ambient solar wind temperature. In order to explain this anomalous solar wind temperature effect, a hypothetical magnetically closed structure in the solar wind is tested. Two different models of

A. Geranios

1981-01-01

212

Transport of transient solar wind particles in Earth's cusps G. K. Parks,1,a  

E-print Network

Transport of transient solar wind particles in Earth's cusps G. K. Parks,1,a E. Lee,1 A. Teste,1 M that transient solar wind particles produced by solar disturbances can appear in the Earth's mid-altitude 5 RE-altitude cusps.11 We have now quantified the cusp particle observations using transient solar wind density

California at Berkeley, University of

213

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

NASA Astrophysics Data System (ADS)

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

Zhou, Wei

214

Charge state composition in coronal hole and CME related solar wind: Latitudinal variations observed by Ulysses and WIND  

NASA Technical Reports Server (NTRS)

Iron charge states in recurrent coronal hole-associated solar wind flows are obtained in the ecliptic by WIND/SMS, while measurements of iron and silicon from the polar coronal holes are available from Ulysses/SWICS. Ulysses/SWICS also provides ion composition of coronal mass ejection (CME)-related solar wind. Both coronal hole-associated and CME-related solar wind charge charges show heliographic latitudinal variations.

Galvin, A. B.; Gloeckler, G.

1997-01-01

215

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

E-print Network

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

Richardson, John

216

The quiet solar wind. [proton and magnetic properties  

NASA Technical Reports Server (NTRS)

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.

Neugebauer, M.

1976-01-01

217

Magnetic field gradients in solar wind plasma and geophysics periods  

E-print Network

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.

A. Bershadskii

2006-11-16

218

The abundances of elements and isotopes in the solar wind  

NASA Technical Reports Server (NTRS)

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.

Gloeckler, George; Geiss, Johannes

1989-01-01

219

SOLAR WIND MODELING WITH TURBULENCE TRANSPORT AND HEATING  

SciTech Connect

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.

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

220

Influence of interplanetary solar wind sector polarity on the ionosphere  

NASA Astrophysics Data System (ADS)

Knowledge of solar sector polarity effects on the ionosphere may provide some clues in understanding of the ionospheric day-to-day variability. A solar-terrestrial connection ranging from solar sector boundary (SB) crossings, geomagnetic disturbance and ionospheric perturbations has been demonstrated. The increases in interplanetary solar wind speed within three days are seen after SB crossings, while the decreases in solar wind dynamic pressure and magnetic field intensity immediately after SB crossings are confirmed by the superposed epoch analysis results. Furthermore, the interplanetary magnetic field (IMF) Bz component turns from northward to southward in March equinox and June solstice as the Earth passes from a solar sector of outward to inward directed magnetic fields, whereas the reverse situation occurs for the transition from toward to away sectors. The F2 region critical frequency (foF2) covering about four solar cycles and total electron content (TEC) during 1998-2011 are utilized to extract the related information, revealing that they are not modified significantly and vary within the range of 15% on average. The responses of the ionospheric TEC to SB crossings exhibit complex temporal and spatial variations and have strong dependencies on season, latitude, and solar cycle. This effect is more appreciable in equinoctial months than in solstitial months, which is mainly caused by larger southward Bz components in equinox. In September equinox, latitudinal profile of relative variations of foF2 at noon is featured by depressions at high latitudes and enhancements in low-equatorial latitudes during IMF away sectors. The negative phase of foF2 is delayed at solar minimum relative to it during other parts of solar cycle, which might be associated with the difference in longevity of major interplanetary solar wind drivers perturbing the Earth's environment in different phases of solar cycle.

liu, jing

2014-05-01

221

A hybrid reconfigurable solar and wind energy system  

NASA Astrophysics Data System (ADS)

We study the feasibility of a novel hybrid solar-wind hybrid system that shares most of its infrastructure and components. During periods of clear sunny days the system will generate electricity from the sun using a parabolic concentrator. The concentrator is formed by individual mirror elements and focuses the light onto high intensity vertical multi-junction (VMJ) cells. During periods of high wind speeds and at night, the same concentrator setup will be reconfigured to channel the wind into a wind turbine which will be used to harness wind energy. In this study we report on the feasibility of this type of solar/wind hybrid energy system. The key mechanisms; optics, cooling mechanism of VMJ cells and air flow through the system were investigated using simulation tools. The results from these simulations, along with a simple economic analysis giving the levelized cost of energy for such a system are presented. An iterative method of design refinement based on the simulation results was used to work towards a prototype design. The levelized cost of the system achieved in the economic analysis shows the system to be a good alternative for a grid isolated site and could be used as a standalone system in regions of lower demand. The new approach to solar wind hybrid system reported herein will pave way for newer generation of hybrid systems that share common infrastructure in addition to the storage and distribution of energy.

Gadkari, Sagar A.

222

Observing MHD Waves in the Solar Wind Acceleration Region  

NASA Astrophysics Data System (ADS)

We have, for the first time, observed and characterized compressive waves propagating both outward and inward in the outer solar corona above 4 Rs. In addition to detecting the waves, we have used them to measure outflow in the all-important wind acceleration region. Because the corona is an MHD system, any disturbance in the corona launches low-frequency waves that propagate at the familiar MHD speeds and serve to communicate that disturbance to other parts of the system. Through careful filtration of synoptic STEREO-A/COR-2 data, we have been able to measure both inbound and outbound waves at all locations in the solar corona. By measuring in/out asymmetries in the wave characteristics we have been able to estimate the solar wind acceleration profile. Further, we are able to estimate the location of the Alfvén surface - the hard-to-measure transition between the corona and the superalfvénic solar wind, and the boundary at which solar magnetic field lines transition from "closed" to "open". There is a great deal of work to be done beyond these preliminary results, which - it is hoped - open a new avenue for understanding coronal dynamics and the origin of the solar wind.

DeForest, Craig; McComas, Dave; Howard, Tim A.

2014-06-01

223

Application of grazing incidence x-ray fluorescence technique to discriminate and quantify implanted solar wind  

SciTech Connect

NASA launched the Genesis return mission to obtain pristine solar wind samples in order to better understand solar wind mechanics, solar physics, and solar system evolution. Unfortunately, the probe crash-landed shattering the collector plates necessitating the application of a grazing incidence x-ray fluorescence technique. This nondestructive methodology differentiates the terrestrial contamination from the low concentration implanted solar wind. Using this technique, the elemental depth distribution is obtained resulting in the determination of absolute solar wind elemental abundance. We describe this application and present the solar wind Fe concentration determination as an example.

Kitts, K.; Choi, Y. [Department of Geology and Environment Geosciences, Northern Illinois University, Davis Hall 312, Normal Road, DeKalb, Illinois 60115 (United States); Eng, P. J.; Ghose, S. K.; Sutton, S. R. [Department of Geophysical Sciences and Consortium for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637 (United States); Rout, B. [Department of Physics, University of North Texas, Denton, Texas 76203 (United States)

2009-03-15

224

Tracking Back the Solar Wind to Its Photospheric Footpoints from Wind Observations - A Statistical Study  

NASA Astrophysics Data System (ADS)

It is of great importance to track the solar wind back to its photospheric source region and identify the related current sheets; this will provide key information for investigating the origin and predictions of the solar wind. We report a statistical study relating the photospheric footpoint motion and in-situ observation of current sheets in the solar wind. We used the potential force-free source-surface (PFSS) model and the daily synoptic charts to trace the solar wind back from 1 AU, as observed by the Wind spacecraft, to the solar surface. As the footpoints move along the solar surface we obtain a time series of the jump times between different points. These jumps can be within a cell and between adjacent cells. We obtained the distribution of the jump times and the distribution for a subset of the jump times in which only jumps between adjacent cells were counted. For both cases, the distributions clearly show two populations. These distributions are compared with the distribution of in-situ current sheets reported in an earlier work of Miao, Peng, and Li ( Ann. Geophys. 29, 237, 2011). Its implications on the origin of the current sheets are discussed.

Huang, Chong; Yan, Yihua; Li, Gang; Deng, Yuanyong; Tan, Baolin

2014-08-01

225

XMM-Newton Observations of Solar Wind Charge Exchange Emission  

NASA Technical Reports Server (NTRS)

We present an XMM-Newton spectrum of diffuse X-ray emission from within the solar system. The spectrum is dominated by O VII and O VIII lines at 0.57 keV and 0.65 keV, O VIII (and possibly Fe XVII) lines at approximately 0.8 keV, Ne IX lines at approximately 0.92 keV, and Mg XI lines at approximately 1.35 keV. This spectrum is consistent with what is 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 less than 1.5 keV) spectral enhancement in one of a series of observations of the Hubble Deep Field North. The X-ray enhancement is concurrent with an enhancement in the solar wind measured by the ACE satellite. The solar wind enhancement reaches a flux level an order of magnitude more intense than typical fluxes at 1 AU, and has ion ratios with significantly enhanced higher ionization states. Whereas observations of the solar wind plasma made at a single point reflect only local conditions which may only be representative of solar wind properties with spatial scales ranging from less than half of an Earth radii (approximately 10 s) to 100 Earth radii, X-ray observations of solar wind charge exchange are remote sensing measurements which may provide observations which are significantly more global in character. Besides being of interest in its own right for studies of the solar system, this emission can have significant consequences for observations of more cosmological objects. It can provide emission lines at zero redshift which are of particular interest (e.g., O VII and O VIII) in studies of diffuse thermal emission, and which can therefore act as contamination in objects which cover the entire detector field of view. We propose the use of solar wind monitoring data, such as from the ACE and Wind spacecraft, as a diagnostic to screen for such possibilities.

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

2004-01-01

226

Theory of discrete wave packets in the solar wind.  

NASA Technical Reports Server (NTRS)

Discrete wave packets were observed by Ogo 5 and earlier satellites. These waves were believed to be in the whistler mode. Since their group velocities were found to be smaller than the solar-wind speed, these waves could not have been generated in the bow shock and could not have propagated upstream later. The present theory discusses a mechanism similar to that of the echo phenomenon in plasma physics discovered in recent years. The present theory enables us to explain (a) why the wave packets were associated with the bow shock, (b) why the wave packets were characterized by coherent oscillations, and (c) why the wave packets had group velocities smaller than the solar wind and yet could still occur in the solar wind. In short, our theory is able to interpret all the essential features deduced from the observational data.

Wu, C. S.

1972-01-01

227

Residual Energy and Imbalance in Solar Wind Turbulence  

NASA Astrophysics Data System (ADS)

The energy spectra of magnetic field and velocity have been well measured in inertial range solar wind turbulence. It is not well understood, however, why these spectra, on average, display different power law behavior. Here, we present new measurements of the residual energy scaling and its variation with relevant solar wind parameters. These measurements are compared to theoretical predictions to determine the cause of this difference. We also examine the local properties of both the residual energy and cross helicity in the solar wind, finding that globally balanced turbulence can consist of patches of local imbalance at all scales and that the residual energy is consistently negative at all scales. The importance of these findings for the turbulence dynamics is discussed.

Chen, C. H.; Salem, C. S.; Bale, S. D.

2012-12-01

228

Deflection of solar wind protons from the Lunar magnetic anomalies  

NASA Astrophysics Data System (ADS)

The first measurements, which was made on the lunar orbits, has shown that Moon has no its intrinsic dipolar magnetic field. However the residual magnetization in returned lunar samples and also the anomalous magnetization of lunar surface (till several hundred nT) was found even in Apollo missions. Observations of Kaguya and Chandrayaan reveal the significant solar wind protons deflection from the lunar surface in particular from the magnetic anomalies regions. Such deflection implies that the magnetic anomalies may act as magnetosphere-like obstacles (mini-magnetospheres), modifying the upstream plasma. We examined the conditions in solar wind and estimated plasma parameters in solar wind and in crustal magnetic field. Then we made the estimation of the possibility of mini-magnetosphere and shock-like structure formation. Also we applied our calculations to the case of big anomaly.

Sadovski, Andrei M.; Skalsky, Alexander A.

2014-05-01

229

Lunar fossil magnetism and perturbations of the solar wind.  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

230

Search for fine scale structures in high latitude solar wind  

NASA Technical Reports Server (NTRS)

About 25 years ago, E. Parker suggested that, as a consequence of the inhomogeneous structure of the corona, the solar wind might consist of adjacent structures with different physical conditions. Since that suggestion was made, the solar wind plasma characteristics have been measured in situ through many experiments, but little has been done to check whether the solar wind shows any evidence for fine scale structures, and, in the affirmative, how far from the Sun these structures persist. A previous work on this subject, by Thieme, Marsch and Schwenn (1990), based on Helios data, lead these authors to claim that the solar wind, between 0.3 and 1 AU, is inhomogeneous on a scale consistent with the hypothesis that the plume-interplume plasmas, at those distances, still retain their identity. In this work we present preliminary results from an investigation of the solar wind fine structure from Ulysses high latitude observations. To this end, we have analyzed data over several months, during 1994, at times well after Ulysses's last encounter with the Heliospheric Current Sheet, when the spacecraft was at latitudes above 50 degrees. These data refer to high speed wind coming from southern polar coronal holes and are best suited for plume-interplume identification. We have performed a power spectra analysis of typical plasma parameters, to test whether the wind plasma consist of two distinct plasma populations. We also examined data to check whether there is any evidence for an horizontal pressure balance over the hypothesized distinct structures. Our results are discussed and compared with previous findings.

Livi, S.; Parenti, S.; Poletto, G.

1995-01-01

231

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

232

Solar wind, Earth's rotation, ocean circulation and climate  

NASA Astrophysics Data System (ADS)

The solar wind flows radially outwards from the Sun until it reaches the irregular and fluctuationg heliopause. The heliosphere expands and contracts with the beat of the Solar activity. The cosmic ray flux within the heliosphere, therefore, fluctuates with the sunspot activity. The solar wind interacts with the Earth’s magnetic field changing its strength and shielding capacity against the cosmic ray flux. This has a direct effect on the atmospheric 14C-pduduction and 10Be consentration. Cosmic ray variations within the atmosphere may affect both airglow and cloudiness and hence has the potential to affect climate, too. Quite another line of solar-terrestrial linkage comes from the solar wind effect on Earth’s rate of rotation. There is a reasonably good correlation between sunspot activity and Earth’s rate of rotation. This implies that the solar wind intensity variations interact with the magnetosphere in the mode of a breaking system; accelerating rotation at solar minima and decelerating rotation at solar maxima. The effects of these changes in rotation are revealed in the mode of changes in climate, sea level and current beat on the Earth’ surface (Sea Level Changes, sections 3 5, www.pog.su.se/sea). During the Spörer, Maunder and Dalton Sunspot Minima, Earth’s experienced a significant speeding-up. This forced cold Arctic water to flow southwards all the way to central Portugal. At the same time, the Gulf Stream was predominantly directed along its southern branch sending hot equatorial water to Gibraltar and NW Africa. This gave rise to strong cold episodes (or “Little Ice Ages”) in western and northwestern Europe in the years 1440-1460, 1687-1703 and 1808-1821 at the same time as the Gibraltar and NW African region experienced warm episodes (or “Little Interglacials”). Besides this solar wind driven changes in rotation, there are also a feedback coupling interchange of angular momentum between the hydrosphere and solid Earth generating a quasi-periodic beat in the oceanic surface current system redistributing ocean-stored heat (recorded in past changes in regional climate) and ocean water volume (recorded in past changes in regional sea level). These changes occur on a decadal to centennial time-scale and constitutes some sort of “super-ENSO” “super-non-ENSO” events. In conclusion, there exists a solar-terrestrial interaction in solar wind variability affecting the Earth’s rate of rotation, which modulates the ocean surface circulation, by this changing the global distribution of ocean-stored heat and water masses.

Mörner, N.-A.

2003-04-01

233

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

SciTech Connect

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.

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

234

SOLAR WIND MAGNETOHYDRODYNAMICS TURBULENCE: ANOMALOUS SCALING AND ROLE OF INTERMITTENCY  

SciTech Connect

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.

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

235

Multi-parametric classification of the solar wind origins  

NASA Astrophysics Data System (ADS)

There are many types of the solar wind sources. They differ in physics and geometry. Our classification is based on dimensionless scaling parameters. Plasma kinetic and MHD regimes define microscopic and macroscopic sources with large and small Knudsen numbers correspondingly. We consider here only macroscopic sources. One-connected solar wind source surfaces represent the most known type in coronal holes. Their geometry and topology is poorly investigated. There are steady state and transient types of the solar wind and corresponding sources with a finite life time according to the Strouhal parameter. The material and energy reservoirs needed for the plasma outflow from the Sun can be stored at different altitudes and in different places in the atmosphere from the photosphere up to the outer corona not higher than several solar radii according to observations. The role of gravity forces diminishes with altitude and regulated by the Froude numbers in streamers and pseudo-streamers. Plasma down-flows were never observed at distances larger than about 6 solar radii. Plasma density, velocity, temperature, ion composition, magnetic and electric fields are combined in many tens of physically different and similar types of origins, which are partially known and to be discovered in future. Thermally driven or magnetically driven winds are well known and delimited by the plasma parameter beta, but we do not know as yet what type is dominating on the Sun as a star globally. This parameter generally around ~ 1, typically being <1 in coronal holes and >1 in active regions from case to case. Laminar and turbulent sources are characterized by corresponding Reynolds numbers. We point out the necessity of the electric field measurements in the corona for better understanding of the solar wind origins of inductive and potential types according to dimensionless Faraday number. Trieste numbers are needed to characterize mostly open, closed or intermittent situations in the sources. We discuss also the astrophysical question about the solar type stars in the stage of unstable accretion.

Igor, Veselovskiy

236

Measurement of Damage Profiles from Solar Wind Implantation  

NASA Technical Reports Server (NTRS)

NASA's Genesis Mission launched from Cape Canaveral in August of 2001 with the goal of collecting solar wind in ultra-pure materials. The samples were returned to Earth more than three years later for subsequent analysis. Although the solar wind is comprised primarily of protons, it also contains ionized species representing the entire periodic table. The Genesis mission took advantage of the natural momentum of these ionized species to implant themselves in specialized collectors including single crystal Si and SiC. The collectors trapped the solar wind species of interest and sustained significant damage to the surface crystal structure as a result of the ion bombardment. In this work, spectroscopic ellipsometry has been used to evaluate the extent of this damage in Si and SiC samples. These results and models are compared for artificially implanted samples and pristine non-flight material. In addition, the flown samples had accumulated a thin film of molecular contamination as a result of outgassing in flight, and we demonstrate that this layer can be differentiated from the material damage. In addition to collecting bulk solar wind samples (continuous exposure), the Genesis mission actually returned silicon exposed to four different solar wind regimes: bulk, high speed, low speed, and coronal mass ejections. Each of these solar wind regimes varies in energy, but may vary in composition as well. While determining the composition is a primary goal of the mission, we are also interested in the variation in depth and extent of the damage layer as a function of solar wind regime. Here, we examine flight Si from the bulk solar wind regime and compare the results to both pristine and artificially implanted Si. Finally, there were four samples which were mounted in an electrostatic "concentrator" designed to reject a large fraction (>85%) of incoming protons while enhancing the concentration of ions mass 4-28 amu by a factor of at least 20. Two of these samples were single crystal 6H silicon carbide. (The others were polycrystalline CVD diamond and amorphous carbon that were not examined in the work.) The ion damaged SiC samples from the concentrator were studied in comparison to the flight Si from the bulk array to understand differences in the extent of the damage.

McNamara, K. M.; Synowicki, R. A.; Tiwald, T. E.

2007-01-01

237

Imaging the Inner Boundary of the Solar Wind  

NASA Astrophysics Data System (ADS)

We have begun analyzing photometric background-subtracted images from STEREO/SECCHI's HI-1 instrument. The images show a clear "flocculated" pattern to the solar wind that is reminiscent of more familiar turbulent flows and more uniformly structured than the top of the corona seen with LASCO C-3 or STEREO/SECCHI COR2. We will present initial quantitative results of this analysis, indicating whether the flocculation pattern is produced locally or advected intact from the corona. This bears heavily on the question of the origin of the variable slow solar wind.

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

2013-07-01

238

Interaction effects between solar wind and comet Bennett  

NASA Technical Reports Server (NTRS)

Observations of the solar wind and the comet Bennett made during the period from Mar. 23 to Apr. 5, 1970 are considered. During this period the position of the comet had been comparatively close to earth at a distance of about 0.7 AU. Plasma data from four space probes and photographs of a number of observatories are taken into account. The relation between a sudden change in the velocity of the solar wind and the occurrence of a pronounced disturbance in the cometary tail is investigated.

Burlaga, L. F.; Donn, B. D.; Rahe, J.; Neugebauer, M.

1973-01-01

239

On Polar Cap Dynamics under Strong Solar Wind Driving  

NASA Astrophysics Data System (ADS)

We investigate how polar cap dynamics, quantified by the polar cap (PC) index, respond to solar wind direct driving and magnetotail energy unloading during intervals of exceptionally large (10 mV/m) reconnection electric field. Using 53 one to two-day intervals that include such extreme fields, we find that, among 11 candidate coupling functions including the electric field of Kan and Lee (1979) and the universal coupling function of Newell et al. (2007), the PC index correlates most closely with the electric field of Kivelson and Ridley (2008), EK-R, a form in which the electric field imposed on the ionosphere by low-latitude magnetopause reconnection saturates at high levels of geomagnetic activity. It is found that nightside magnetospheric processes, as represented by an unloading AL index (ALU), make a significant contribution to the PC index. A linear model is constructed to relate the PC index to its solar wind driver and magnetotail driver, i.e. PC ? ?0 + ?1zs(EK-R) + ?2zs(ALU), where ?0, ?1 and ?2 are estimated from regression, and zs( ) is a normalization function. Based on this model, it is estimated that the portion of the PC index directly driven by the solar wind electric field outweighs the contribution arising from energy release in the magnetotail by roughly a factor of 2. The solar wind dynamic pressure (pdyn) does not play a key role in controlling the PC index. However, under intense solar wind driving, the number density (n) can influence the solar wind-magnetosphere coupling by changing the solar wind Alfvén conductance, which is incorporated in EK-R. The validity of the linear model is verified by comparing its results with those obtained from a more general, non-linear model, PC ? ? + f1(EK-R) + f2(ALU), where ? is a constant, and f1( ), f2( ) are arbitrary smooth functions. It is found that, except in anomalous events during which the auroral oval expanded poleward to the latitude of the PC index station and the index increased because of proximity to auroral zone currents, the linear model is a good approximation, since more than 70% of the variation in the PC index is explained by the model. The linear model provides a useful tool to study the coupling between the solar wind, magnetosphere and ionosphere.

Gao, Y.; Kivelson, M. G.; Walker, R. J.; Weygand, J. M.

2012-12-01

240

Coronal Magnetic Field Topology and Source of Fast Solar Wind  

NASA Technical Reports Server (NTRS)

We have developed a steady state, 2D semi-empirical MHD model of the solar corona and the solar wind with many surprising results. This model for the first time shows, that the boundary between the fast and the slow solar wind as observed by Ulysses beyond 1 AU, is established in the low corona. The fastest wind observed by Ulysses (680-780 km/s) originates from the polar coronal holes at 70 -90 deg. latitude at the Sun. Rapidly diverging magnetic field geometry accounts for the fast wind reaching down to a latitude of +/- 30 deg. at the orbit of Earth. The gradual increase in the fast wind observed by Ulysses, with latitude, can be explained by an increasing field strength towards the poles, which causes Alfven wave energy flux to increase towards the poles. Empirically, there is a direct relationship between this gradual increase in wind speed and the expansion factor, f, computed at r greater than 20%. This relationship is inverse if f is computed very close to the Sun.

Guhathakurta, M.; Sittler, E.; Fisher, R.; McComas, D.; Thompson, B.

1999-01-01

241

Bow Shock in Interaction of Solar Wind with Cometary Coma  

NASA Astrophysics Data System (ADS)

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).

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

2003-05-01

242

78 FR 77447 - California Wind Energy Association, First Solar, Inc. v. California Independent System Operator...  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Federal Energy Regulatory Commission...EL14-14-000] California Wind Energy Association, First Solar, Inc. v. California Independent...2013), California Wind Energy Association and First Solar, Inc....

2013-12-23

243

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.

244

Origin of the Wang-Sheeley-Arge Solar Wind Model  

NASA Astrophysics Data System (ADS)

A correlation between solar wind speed at Earth and the amount of field line expansion in the corona was verified in 1989 using 22 years of solar and interplanetary observations. This talk will trace the history of this discovery from its birth 15 years earlier in the Skylab era to its current use as a space weather forecasting technique. This research was supported by NASA and ONR.

Sheeley, Neil R.

2014-06-01

245

Elemental and isotopic abundances in the solar wind  

NASA Technical Reports Server (NTRS)

The use of collecting foils and lunar material to assay the isotopic composition of the solar wind is reviewed. Arguments are given to show that lunar surface correlated gases are likely to be most useful in studying the history of the solar wind, though the isotopic abundances are thought to give a good approximation to the solar wind composition. The results of the analysis of Surveyor material are also given. The conditions leading to a significant component of the interstellar gas entering the inner solar system are reviewed and suggestions made for experimental searches for this fraction. A critical discussion is given of the different ways in which the basic solar composition could be modified by fractionation taking place between the sun's surface and points of observation such as on the Moon or in interplanetary space. An extended review is made of the relation of isotopic and elemental composition of the interplanetary gas to the dynamic behavior of the solar corona, especially processes leading to fractionation. Lastly, connection is made between the subject of composition, nucleosynthesis and the convective zone of the sun, and processes leading to modification of initial accretion of certain gases on the Earth and Moon.

Geiss, J.

1972-01-01

246

Slow and fast solar wind - data selection and statistical analysis  

NASA Astrophysics Data System (ADS)

In this work we consider the important problem of selection of slow and fast solar wind data measured in-situ by the Ulysses spacecraft during two solar minima (1995-1997, 2007-2008) and solar maximum (1999-2001). To recognise different types of solar wind we use a set of following parameters: radial velocity, proton density, proton temperature, the distribution of charge states of oxygen ions, and compressibility of magnetic field. We present how this idea of the data selection works on Ulysses data. In the next step we consider the chosen intervals for fast and slow solar wind and perform statistical analysis of the fluctuating magnetic field components. In particular, we check the possibility of identification of inertial range by considering the scale dependence of the third and fourth orders scaling exponents of structure function. We try to verify the size of inertial range depending on the heliographic latitudes, heliocentric distance and phase of the solar cycle. Research supported by the European Community's Seventh Framework Programme (FP7/2007 - 2013) under grant agreement no 313038/STORM.

Wawrzaszek, Anna; Macek, Wies?aw M.; Bruno, Roberto; Echim, Marius

2014-05-01

247

Anisotropic winds from close-in extra-solar planets  

E-print Network

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.

James M. Stone; Daniel Proga

2008-12-13

248

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

Microsoft Academic Search

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

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

1998-01-01

249

Solar Wind Characteristics from SOHO-Sun-Ulysses Quadrature Observations  

NASA Technical Reports Server (NTRS)

Over the past few years, we have been running SOHO (Solar and Heliospheric Observatory)-Sun-Ulysses quadrature campaigns, aimed at comparing the plasma properties at coronal altitudes with plasma properties at interplanetary distances. Coronal plasma has been observed by SOHO experiments: mainly, we used LASCO (Large Angle and Spectrometric Coronagraph Experiment) data to understand the overall coronal configuration at the time of quadratures and analyzed SUMER (Solar Ultraviolet Measurements of Emitted Radiation), CDS (Coronal Diagnostic Spectrometer) and UVCS (Ultraviolet Coronagraph Spectrometer) data to derive its physical characteristics. At interplanetary distances, SWICS (Solar Wind Ion Composition Spectrometer) and SWOOPS (Solar Wind Observation over the Poles of the Sun) aboard Ulysses provided us with interplanetary plasma data. Here we report on results from some of the campaigns. We notice that, depending on the geometry of the quadrature, i.e. on whether the radial to Ulysses traverses the corona at high or low latitudes, we are able to study different kinds of solar wind. In particular, a comparison between low-latitude and high-latitude wind, allowed us to provide evidence for differences in the acceleration of polar, fast plasma and equatorial, slow plasma: the latter occurring at higher levels and through a more extended region than fast wind. These properties are shared by both the proton and heavy ions outflows. Quadrature observations may provide useful information also on coronal vs. in situ elemental composition. To this end, we analyzed spectra taken in the corona, at altitudes ranging between approx. 1.02 and 2.2 solar radii, and derived the abundances of a number of ions, including oxygen and iron. Values of the O/Fe ratio, at coronal levels, have been compared with measurements of this ratio made by SWICS at interplanetary distances. Our results are compared with previous findings and predictions from modeling efforts.

Poletto, Giannina; Suess, Steve T.; Six, N. Frank (Technical Monitor)

2002-01-01

250

Enabling Technologies for High Penetration of Wind and Solar Energy  

SciTech Connect

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.

Denholm, P.

2011-01-01

251

An assessment of solar and wind energy from the electric utility view point  

Microsoft Academic Search

The paper discusses briefly the prospects of several technologies for supplementing energy resources in the coming decade, including wind energy, biomass, solar thermal conversion, ocean thermal gradient systems, and photovoltaic conversion, and then gives an assessment of solar and wind energy economics. Break-even capital cost limits for solar and wind energy systems have been calculated for different fuel costs, interest

R. Ramakumar; W. L. Hughes

1975-01-01

252

Title: Feasibility Study for 20 MW Hybrid Solar and Wind Park in Colombia  

E-print Network

1 of 2 Title: Feasibility Study for 20 MW Hybrid Solar and Wind Park in Colombia Principal a detailed and realistic ~ 4 MW solar and ~ 16 MW wind energy feasibility assessment for a renewable energy the realistic ROI for a potential 20 MW solar/wind farm. The information generated will be sufficiently detailed

Johnson, Eric E.

253

Electron heat flux dropouts in the solar wind: evidence for interplanetary magnetic field reconnection  

Microsoft Academic Search

Electron heat flux dropout events have been observed in the solar wind using the ISEE 3 plasma electron data set. These events manifest themselves as dropouts of the solar wind halo electrons which are normally found streaming outward along the local magnetic field. These dropouts leave nearly isotropic distributions of solar wind halo electrons, and consequently, the heat flux in

D. J. McComas; J. T. Gosling; J. L. Phillips; S. J. Bame; J. G. Luhmann; E. J. Smith

1989-01-01

254

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

Microsoft Academic Search

The scope, need and feasibility of a solar-wind desalinization (SOWIDE) system is examined. A climatological study shows the scope and need where a water deficit, a saline source and solar and wind power coincide. Representative stations around the globe serve as examples. When climatological data are used, relatively few locations meet all requirements. Optimization of wind and solar energy through

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

1980-01-01

255

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

Microsoft Academic Search

The scope, need and feasibility of a solar-wind desalinization (SOWIDE) system is examined. A climatological study shows the scope and need where a water deficit, a saline source and solar and wind power coincide. Representative stations around the globe serve as examples. When climatological data are used, relatively few locations meet all requirements. Optimization of wind and solar energy through

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

1980-01-01

256

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

Microsoft Academic Search

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

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

2005-01-01

257

The critical solar wind pressure for IMF penetration into the Venus ionosphere  

Microsoft Academic Search

Early observations and simulations have revealed that the occurrence of IMF penetration into the Venus ionosphere depends on the upstream solar wind pressure, and that IMF is transported into the ionosphere by the downward convection when the solar wind dynamic pressure is relatively large. In this paper, we investigated the critical solar wind pressure for the IMF penetration, by using

H. Jin; K. Maezawa; T. Mukai

2008-01-01

258

Solar Wind Variations Related to Fluctuations of the North Atlantic Oscillation  

Microsoft Academic Search

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

Fredrik Boberg; Henrik Lundstedt

2002-01-01

259

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

E-print Network

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

Russell, Christopher T.

260

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

Microsoft Academic Search

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

M. A. Elhadidy; S. M. Shaahid

1999-01-01

261

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

Microsoft Academic Search

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

Hongxing Yang; Zhou Wei; Lou Chengzhi

2009-01-01

262

Proposed model for Saturn's auroral response to the solar wind: Centrifugal instability model  

Microsoft Academic Search

We present a model of Saturn's global auroral response to the solar wind as observed by simultaneous Hubble Space Telescope (HST) auroral images and Cassini upstream measurements of the solar wind taken during the month of January 2004. These observations show a direct correlation between solar wind dynamic pressure and (1) auroral brightening toward dawn local time, (2) an increase

E. C. Sittler Jr; M. F. Blanc; J. D. Richardson

2006-01-01

263

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

E-print Network

in the arrays; approximately half are silicon, the rest are for solar-wind components not retained andTHE 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

264

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

E-print Network

Are energetic electrons in the solar wind the source of the outer radiation belt? Xinlin Li,1 D. N the correlation of en- ergetic electrons in the 20-200 keV range in the solar wind and of high speed solar wind streams with relativistic elec- trons in the magnetosphere to determine whether energetic electrons

Li, Xinlin

265

Solar wind interaction with Comet Bennett (1969i  

NASA Technical Reports Server (NTRS)

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.

Burlaga, L. F.; Rahe, J.; Donn, B. D.; Neugebauer, M.

1972-01-01

266

Polar and high latitude substorms and solar wind conditions  

NASA Astrophysics Data System (ADS)

All substorm disturbances observed in polar latitudes can be divided into two types: polar, which are observable at geomagnetic latitudes higher than 70° in the absence of substorms below 70°, and high latitude substorms, which travel from auroral (<70°) to polar (>70°) geomagnetic latitudes. The aim of this study is to compare conditions in the IMF and solar wind, under which these two types of substorms are observable on the basis of data from meridional chain of magnetometers IMAGE and OMNI database for 1995, 2000, and 2006-2011. In total, 105 polar and 55 high latitude substorms were studied. It is shown that polar substorms are observable at a low velocity of solar wind after propagation of a high-speed recurrent stream during the late recovery phase of a magnetic storm. High latitude substorms, in contrast, are observable with a high velocity of solar wind, increased values of the Bz component of the IMF, the Ey component of the electric field, and solar wind temperature and pressure, when a high-speed recurrent stream passes by the Earth.

Despirak, I. V.; Lyubchich, A. A.; Kleimenova, N. G.

2014-09-01

267

Seasonal dependence and solar wind control of transpolar arc luminosity  

Microsoft Academic Search

The influence of the solar wind and the interplanetary magnetic field (IMF) on the luminosity of transpolar arcs (TPAs) is examined by taking into account seasonal effects. The study focuses on those transpolar arcs that appear after an IMF By sign change during steady northward IMF. It includes 21 northern hemisphere events identified in a previous study from global UV

A. Kullen; J. A. Cumnock; T. Karlsson

2008-01-01

268

Seasonal dependence and solar wind control of transpolar arc luminosity  

Microsoft Academic Search

The influence of the solar wind and the interplanetary magnetic field (IMF) on the luminosity of transpolar arcs (TPAs) is examined by taking into account seasonal effects. The study focuses on those transpolar arcs that appear after an IMF B y sign change during steady northward IMF. It includes 21 northern hemisphere events identified in a previous study from global

A. Kullen; J. A. Cumnock; T. Karlsson

2008-01-01

269

Observations of Kinetic Scale Turbulence in the Solar Wind  

NASA Astrophysics Data System (ADS)

The solar wind has been observed to be a turbulent plasma for many decades. It provides a unique environment in which spacecraft can directly measure the turbulent fluctuations at the small scales on which the turbulence is dissipated, providing the detail necessary to identify the nature of these small-scale fluctuations, information critical for unraveling the physical mechanisms by the which the turbulence is dissipated. How the turbulent energy is dissipated in the solar wind plasma is far from being well understood. The underlying question of the nature of the fluctuations is still under debate. Indeed, the steepening of the observed power spectra, although originally attributed to ion cyclotron damping, is now believed to be due to the dispersive nature of the fluctuations, with two leading interpretations in terms of Kinetic Alfven Wave Turbulence and/or Whistler Wave Turbulence - not as linear waves but rather as nonlinear turbulence with wave-like properties. Several recent studies have focussed on developing various tests to distinguish between both wave modes. Other possible contributions to the spectrum at these scales include current sheets and/or kinetic instabilities, although their effect remains to be fully investigated. We present here a review of the recent ground-breaking observations in the dissipation range of solar wind turbulence. We discuss the different available interpretations and their impact on the heating of the solar wind plasma.

Salem, C. S.

2012-12-01

270

Solar wind current sheet observations over multiple length scales  

NASA Astrophysics Data System (ADS)

The variable separation between the STEREO-A (STA) and STEREO-B (STB) spacecraft early in their mission presents a unique opportunity to study thin current sheets in the solar wind at length scales ranging from 0.1 to 2,000 Earth radii (Re). An automated algorithm was developed to detect the magnetic field directional discontinuities indicative of thin current sheets in the solar wind. Using data from December 2006 through March 2007, over 30,000 current sheets per spacecraft were found. An automated algorithm was also developed to identify the subset of current sheets that propagate between STA and STB. The geometry and length scales of current sheets propagating between STA and STB were inferred from magnetic field and solar wind velocity vectors. Analysis of the identified current sheets shows that: 1) Current sheets observed by STA-only or STB-only show distributions of spread angle, sheet orientation, and waiting time that agree well with previous studies. 2) Distributions of these same properties for current sheets observed by both STA and STB are significantly different from the single-spacecraft current sheet populations. 3) At 0.1 Re spacecraft separation, only half of current sheets observed by either spacecraft individually are observed at both spacecraft, and this fraction falls quickly with increasing separation. These observations indicate distinct populations of solar wind current sheet differentiated either by their rate of temporal evolution or spatial scale.

Malaspina, D.; Gosling, J. T.

2011-12-01

271

Hybrid code simulations of the solar wind interaction with Pluto  

Microsoft Academic Search

Pluto's low gravity implies that the atmosphere is only weakly bound and that significant hydrodynamic outflow can exist. Though surface spectroscopy of Pluto has revealed methane frost, the dominant escaping neutral gas is thought to be N2. These escaping neutrals are photoionized, and the heavy ions (N2+) move away from Pluto in the direction perpendicular to the solar wind flow

P. A. Delamere

2009-01-01

272

Interplanetary scintillation observations of interaction regions in the solar wind  

Microsoft Academic Search

Co-rotating interaction regions (CIRs) between fast and slow streams of plasma are a prominent feature of the solar wind. Measurements of interplanetary scintillation (IPS) using the three widely separated antennas of the EISCAT facility have been used to detect the compression regions at the leading edges of interaction regions and to determine the location and velocity of the structure. Observations

A. R. Breen; P. J. Moran; C. A. Varley; W. P. Wilkinson; P. J. S. Williams; W. A. Coles; A. Lecinski; J. Markkanen

1998-01-01

273

Interplanetary scintillation observations of interaction regions in the solar wind  

Microsoft Academic Search

Co-rotating interaction regions (CIRs) between fast and slow streams of plasma are a prom- inent feature of the solar wind. Measurements of interplanetary scintillation (IPS) using the three widely separated antennas of the EISCAT facility have been used to detect the compression regions at the leading edges of interaction regions and to determine the location and velocity of the structure.

A. R. Breen; P. J. Moran; C. A. Varley; W. P. Wilkinson; P. J. S. Williams; W. A. Coles; A. Lecinski; J. Markkanen

1998-01-01

274

Statistical and wavelet analysis of the solar wind data  

Microsoft Academic Search

We perform statistical and wavelet analysis of three time series based on the solar wind velocity of the year 2000, the original time series and two filtered components. We use the Haar Wavelet Transform to separate this annual time-series into two parts, corresponding to high and low frequencies. We then calculate the kurtosis and skewness parameters for the three time-series.

Maur ´ icio; Jose Alves Bolzan; do Para ´ iba

2005-01-01

275

Pioneer 10 observations of the solar wind interaction with Jupiter  

Microsoft Academic Search

Detailed analysis of the Pioneer 10 plasma analyzer experiment flight data during the Jupiter flyby in late November and early December 1973 has been performed. The observations show that the interaction of Jupiter's magnetic field with the solar wind is similar in many ways to that at earth, but the scale size is over 100 times larger. Jupiter is found

J. H. Wolfe; J. D. Mihalov; H. R. Collard; D. D. McKibbin; L. A. Frank; D. S. Intriligator

1974-01-01

276

Iron charge states observed in the solar wind  

SciTech Connect

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.

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

1983-11-01

277

Iron charge states observed in the solar wind  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

278

Solar Wind Monitoring with SWIM-SARA Onboard Chandrayaan-1  

NASA Astrophysics Data System (ADS)

The SARA experiment aboard the Indian lunar mission Chandrayaan-1 consists of two instruments: Chandrayaan-1 Energetic Neutral Analyzer (CENA) and the SolarWind Monitor (SWIM). CENA will provide measurements of low energy neutral atoms sputtered from lunar surface in the 0.01-3.3 keV energy range by the impact of solar wind ions. SWIM will monitor the solar wind flux precipitating onto the lunar surface and in the vicinity of moon. SWIM is basically an ion-mass analyzer providing energy-per-charge and number density of solar wind ions in the energy range 0.01-15 keV. It has sufficient mass resolution to resolve H+ , He++, He+, O++, O+, and >20 amu, with energy resolution 7% and angular resolution 4:5° × 22:5. The viewing angle of the instrument is 9° × 180°.Mechanically, SWIM consists of a sensor and an electronic board that includes high voltage supply and sensor electronics. The sensor part consists of an electrostatic deflector to analyze the arrival angle of the ions, cylindrical electrostatic analyzer for energy analysis, and the time-of-flight system for particle velocity determination. The total size of SWIM is slightly larger than a credit card and has a mass of 500 g.

Bhardwaj, A.; Barabash, S.; Sridharan, R.; Wieser, M.; Dhanya, M. B.; Futaana, Y.; Asamura, K.; Kazama, Y.; McCann, D.; Varier, S.; Vijayakumar, E.; Mohankumar, S. V.; Raghavendra, K. V.; Kurian, T.; Thampi, R. S.; Andersson, H.; Svensson, J.; Karlsson, S.; Fischer, J.; Holmstrom, M.; Wurz, P.; Lundin, R.

279

Laboratory simulations of the solar wind-comet interactions  

SciTech Connect

The laboratory simulation of the solar wind interaction with a comet is carried out to study the cometary neutral gas ionization and the influence of the ionization process on bow shock formation. The UCR T-1 facility is used for the simulations, an ice ball as a comet model and photographs and data are taken under a variety of solar wind velocity, interplanetary magnetic field and comet configurations. The results show that the cometary neutral gas ionization depends on both the velocity of the solar wind and the interplanetary magnetic field. The plasma cloud surrounding the comet is visible only when the solar wind velocity and IMF are both above minimum values. This velocity dependent phenomena is explained by Alfven's critical ionization velocity effect. This critical magnetic field effect may be caused by the lower hybrid instability triggering ionization of the neutral gas by plasma flow. The magnetic component of electromagnetic instabilities are investigated both with and without the CIV effect. Four groups of waves are found and identified to lie in the range of lower hybrid waves. The cometary bow shock formation is studied with the neutral gas ionization conditions satisfied. A contact discontinuity and a collisional bow shock are found.

Chang, Tsuey-Fen.

1988-01-01

280

Air emissions due to wind and solar power.  

PubMed

Renewables portfolio standards (RPS) encourage large-scale deployment of wind and solar electric power. Their power output varies rapidly, even when several sites are added together. In many locations, natural gas generators are the lowest cost resource available to compensate for this variability, and must ramp up and down quickly to keep the grid stable, affecting their emissions of NOx and CO2. We model a wind or solar photovoltaic plus gas system using measured 1-min time-resolved emissions and heat rate data from two types of natural gas generators, and power data from four wind plants and one solar plant. Over a wide range of renewable penetration, we find CO2 emissions achieve approximately 80% of the emissions reductions expected if the power fluctuations caused no additional emissions. Using steam injection, gas generators achieve only 30-50% of expected NOx emissions reductions, and with dry control NOx emissions increase substantially. We quantify the interaction between state RPSs and NOx constraints, finding that states with substantial RPSs could see significant upward pressure on NOx permit prices, if the gas turbines we modeled are representative of the plants used to mitigate wind and solar power variability. PMID:19238948

Katzenstein, Warren; Apt, Jay

2009-01-15

281

Energy coupling between the solar wind and the magnetosphere  

Microsoft Academic Search

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 ?

S.-I. Akasofu

1981-01-01

282

Depletion of solar wind plasma near a planetary boundary  

Microsoft Academic Search

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

B. J. Zwan; R. A. Wolf

1976-01-01

283

Structural stability of concrete wind turbines and solar chimney towers exposed to dynamic wind action  

Microsoft Academic Search

Apart from burning classical fossil resources or generating nuclear power, alternatives have been developed, like the classical ways to capture energy from wind, water and sun, or the innovative solar chimney concept.The paper presents some structural aspects of classical wind energy turbines, like their high-cycle dynamic loading and reaction as well as their fatigue behaviour. Actual research results concerning pre-stressed

Reinhard Harte; Gideon P. A. G. Van Zijl

2007-01-01

284

Solar wind spatial scales in and comparisons of hourly Wind and ACE plasma and magnetic field data  

Microsoft Academic Search

Hourly averaged interplanetary magnetic field (IMF) and plasma data from the Advanced Composition Explorer (ACE) and Wind spacecraft, generated from 1 to 4 min resolution data time-shifted to Earth have been analyzed for systematic and random differences. ACE moments-based proton densities are larger than Wind\\/Solar Wind Experiment (SWE) fits-based densities by up to 18%, depending on solar wind speed. ACE

J. H. King; N. E. Papitashvili

2005-01-01

285

Drag of the Venusian Atmosphere by Solar Wind  

NASA Astrophysics Data System (ADS)

One of the more efficient mechanisms of volatiles lost in the non-magnetic planets is its drag by solar wind. In this study it is explored this type of erosion for Venus and it is obtained some numerical results leaving from plausible models of degassing and drag. The obtained results from this study are: Venus had degassed, in all its history, of the order of 286.87 TAM of volatiles (1 TAM = 1 Terrestrial Atmospheric Mass = 5.28x1018 kg), i.e., 1.515x1021 kg. Since current mass of the planet's atmosphere is 89.92 TAM the volatiles mass that Venus has lost in the same period is of the order of 196.95 TAM, i.e., 1.04x1021 kg. The drag capacity of the solar wind in the first Ga of the planet's life was very large such that it could drag of the order of 108 TAM if Venus had have it. Degasification did not could compete with the drag that maintains the planet free of volatiles and at the solar wind flowing directly in surface. After this first Ga in the following 3.6 Ga the drag capacity of the solar wind reduced drastically and then the solar wind only could drag at the most of the order of 88 TAM of volatiles. The mass dragged by the solar wind in all the history of Venus fluctuate between 70 and 200 TAM, i.e., between 3.7x1020 kg and 1.06x1021 kg. In last 3.6 Ga the dragged mass by solar wind fluctuate between 11 and 61 TAM and y the last 500 Ma between 0.32 and 0.41 TAM. The lost by other mechanisms fluctuate between 1 and 130 TAM. For the scenarios of more loss the usual mechanisms could not explain the quantity of lost volatiles, for this it is proposed the hypotheses of the Great Impact (the collision of Venus with a body larger than Moon 500 Ma ago) this hypotheses not only explain the lost of volatiles but also other aspects do not understand of Venus, like its slowly and retrograde rotation and the renovation of all its surface 500 Ma ago.

Durand-Manterol, H.

2006-12-01

286

Auroral Acceleration, Solar Wind Driving, and Substorm Triggering (Invited)  

NASA Astrophysics Data System (ADS)

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.

Newell, P. T.; Liou, K.

2010-12-01

287

Solar wind induced magnetic field around the unmagnetized Earth  

E-print Network

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.

G. T. Birk; H. Lesch; C. Konz

2004-04-29

288

HEMISPHERIC ASYMMETRIES IN THE POLAR SOLAR WIND OBSERVED BY ULYSSES NEAR THE MINIMA OF SOLAR CYCLES 22 AND 23  

SciTech Connect

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.

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

289

The Heating & Acceleration of the Solar Wind  

E-print Network

Wind Fluctuations Magnetic field power spectrum consistent w/ Kolmogorov (above the ion Larmor radius favors waves · Alfven waves: primary observed fluctuation & least damped MHD mode in collisionless #12;Wave Excitation/Launching · Small-scale Magnetic Activity High Freq. Alfven Waves · ~ Hz

Wurtele, Jonathan

290

Global aspects of stream evolution in the solar wind  

SciTech Connect

A spatially variable coronal expansion, when coupled with solar rotation, leads to the formation of high speed solar wind streams which evolve considerably with increasing heliocentric distance. Initially the streams steepen for simple kinematic reasons, but this steepening is resisted by pressure forces, leading eventually to the formation of forward-reverse shock pairs in the distant heliosphere. The basic physical processes responsible for stream steepening an evolution are explored and model calculations are compared with actual spacecraft observations of the process. The solar wind stream evolution problem is relatively well understood both observationally and theoretically. Tools developed in achieving this understanding should be applicable to other astrophysical systems where a spatially or temporally variable outflow is associated with a rotating object. 27 references, 13 figures.

Gosling, J.T.

1984-01-01

291

Observation of the multifractal spectrum in solar wind turbulence by Ulysses at high latitudes  

Microsoft Academic Search

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

Anna Wawrzaszek; Wieslaw M. Macek

2010-01-01

292

Characteristics of the solar wind controlled auroral emissions  

NASA Astrophysics Data System (ADS)

We performed a high-time resolution (5 min) correlative study of the energy deposition rate in the northern auroral zone with the concurrent solar wind plasma and interplanetary magnetic field (IMF) observations for a 4 month period from March 30 to July 29, 1996. Auroral power, inferred by auroral emissions, was derived from images acquired by the ultraviolet imager (UVI) on board the Polar satellite, and the interplanetary parameters were based on Wind observations. It is found that dayside aurorae in the afternoon sector (65°-80° magnetic latitude (MLAT) and 1300-1800 magnetic local time (MLT)) are more active for large IMF cone angles and large solar wind electric fields. This result can be attributed to the manifestation of the antiparallel magnetic field merging in different locations and the partial ``penetration'' of the IMF on the dayside magnetopause. The integrated nightside (60°-75° MLAT and 2000-0100 MLT) auroral brightness is moderately correlated with the north-south component of the IMF and the solar wind speed with correlation coefficients of 0.49 and 0.35, respectively. The mean nightside auroral power is found to be approximately linearly proportional to the IMF Bz with a constant slope of 2 GW/nT. The solar wind speed, however, affects the nightside auroral power for both polarities of IMF Bz. Interestingly, the solar wind dynamic pressure shows no effect on the nightside auroral brightness. All these findings indicate that both reconnection and viscous-like interaction mechanisms play an important role in producing auroral emissions in the night sector. It is also found that the nightside auroral brightness responds to the southward turning of the IMF with a peak delay time of ~60 min. This result favors the model of loading-unloading magnetosphere. We also found that a negative IMF By condition favors the nightside auroral activity, and we attributed this effect to the partial penetration of the IMF By. Finally, the response function for nightside aurora is given as ~VBT4sin4(?c/2) with a median correlation coefficient of 0.63, indicating that there may be other factors other than the solar wind and IMF responsible for lightening up the northern-southern hemispheric sky.

Liou, K.; Newell, P. T.; Meng, C.-I.; Brittnacher, M.; Parks, G.

1998-08-01

293

Solar Panel Buffeted by Wind at Phoenix Site  

NASA Technical Reports Server (NTRS)

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.

2008-01-01

294

Long-term-average, solar cycle, and seasonal response of magnetospheric energetic electrons to the solar wind speed  

E-print Network

Magnetospheric Physics: Energetic particles, trapped; 2784 Magnetospheric Physics: Solar wind/ magnetosphereLong-term-average, solar cycle, and seasonal response of magnetospheric energetic electrons to the solar wind speed D. Vassiliadis,1 A. J. Klimas,2 S. G. Kanekal,3 D. N. Baker,3 and R. S. Weigel4

295

Relationship between the IMF azimuthal angle and solar wind velocity  

NASA Astrophysics Data System (ADS)

The relationship between the IMF azimuthal angle and plasma velocity has been studied independently for three types of solar wind streams (recurrent and transient high-speed streams and low-speed background wind) based on the interplanetary medium parameters measured in the near-Earth orbits in 1964-1996. The relationships between the IMF azimuthal angle cotangent and plasma velocity are close to linear but strongly differ from one another and from the theoretical relationship for all types of streams. These differences area caused by the magnetic field disturbance on the time scales smaller than a day, and the effect of this disturbance has been studied quantitatively. The effective periods of rotation of the IMF sources on the Sun, depending on the solar cycle phase, have been obtained from the relations between the IMF azimuthal angle cotangent and plasma velocity. During the most part of the solar cycle, the periods of rotation of the IMF sources are close to the period of rotation of the solar equator but abruptly increase to the values typical of the solar circumpolar zones in the years of solar minimums.

Erofeev, D. V.

2008-04-01

296

Extended Coronal Heating and Solar Wind Acceleration over the Solar Cycle  

NASA Astrophysics Data System (ADS)

This paper reviews our growing understanding of the physics behind coronal heating (in open-field regions) and the acceleration of the solar wind. Many new insights have come from the last solar cycle's worth of observations and theoretical work. Measurements of the plasma properties in the extended corona, where the primary solar wind acceleration occurs, have been key to discriminating between competing theories. We describe how UVCS/SOHO measurements of coronal holes and streamers over the last 14 years have provided clues about the detailed kinetic processes that energize both fast and slow wind regions. We also present a brief survey of current ideas involving the coronal source regions of fast and slow wind streams, and how these change over the solar cycle. These source regions are discussed in the context of recent theoretical models (based on Alfvén waves and MHD turbulence) that have begun to successfully predict both the heating and acceleration in fast and slow wind regions with essentially no free parameters. Some new results regarding these models—including a quantitative prediction of the lower density and temperature at 1 AU seen during the present solar minimum in comparison to the prior minimum—are also shown.

Cranmer, S. R.; Kohl, J. L.; Miralles, M. P.; van Ballegooijen, A. A.

2010-06-01

297

Predictions of the solar wind speed by the probability distribution function model  

NASA Astrophysics Data System (ADS)

AbstractThe near-Earth space environment is strongly driven by the <span class="hlt">solar</span> <span class="hlt">wind</span> and interplanetary magnetic field. This study presents a model for predicting the <span class="hlt">solar</span> <span class="hlt">wind</span> speed up to 5 days in advance. Probability distribution functions (PDFs) were created that relate the current <span class="hlt">solar</span> <span class="hlt">wind</span> speed and slope to the future <span class="hlt">solar</span> <span class="hlt">wind</span> speed, as well as the <span class="hlt">solar</span> <span class="hlt">wind</span> speed to the <span class="hlt">solar</span> <span class="hlt">wind</span> speed one <span class="hlt">solar</span> rotation in the future. It was found that a major limitation of this type of technique is that the <span class="hlt">solar</span> <span class="hlt">wind</span> periodicity is close to 27 days but can be from about 22 to 32 days. Further, the optimum lag between two <span class="hlt">solar</span> rotations can change from day to day, making a prediction of the future <span class="hlt">solar</span> <span class="hlt">wind</span> speed based solely on the <span class="hlt">solar</span> <span class="hlt">wind</span> speed approximately 27 days ago quite difficult. It was found that using a linear combination of the <span class="hlt">solar</span> <span class="hlt">wind</span> speed one <span class="hlt">solar</span> rotation ago and a prediction of the <span class="hlt">solar</span> <span class="hlt">wind</span> speed based on the current speed and slope is optimal. The linear weights change as a function of the prediction horizon, with shorter prediction times putting more weight on the prediction based on the current <span class="hlt">solar</span> <span class="hlt">wind</span> speed and the longer prediction times based on an even spread between the two. For all prediction horizons from 8 h up to 120 h, the PDF Model is shown to be better than using the current <span class="hlt">solar</span> <span class="hlt">wind</span> speed (i.e., persistence), and better than the Wang-Sheeley-Arge Model for prediction horizons of 24 h.</p> <div class="credits"> <p class="dwt_author">Bussy-Virat, C. D.; Ridley, A. J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">298</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFMGC52B..03J"> <span id="translatedtitle">Physical-Statistical Downscaling of Model <span class="hlt">Wind</span> Speed and <span class="hlt">Solar</span> Radiation: Forecasting <span class="hlt">Wind</span> and <span class="hlt">Solar</span> Energy in Nevada</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">High temporal variability in <span class="hlt">wind</span> speed and downward shortwave flux at ground surface has been evidenced by observations. The values also change spatially due to topography, cloud cover and other characteristics of the planetary boundary layer. Numerical weather prediction provides grid-scale resolved values; however, the sub-grid-scale part generally contributes more to variances of model <span class="hlt">wind</span> speed and/or <span class="hlt">solar</span> radiation. This part is parameterized, and not explicitly resolved. Electricity integration costs for <span class="hlt">wind</span> and/or <span class="hlt">solar</span> energy may be decreased if the variances and range of uncertainty are well explained to transmission system operators/electricity traders. In this study, month-long simulations in the summer and winter were conducted using the Weather Research and Forecasting (WRF) model. Observed <span class="hlt">wind</span> and <span class="hlt">solar</span> radiation data from four 50-m meteorological towers and one 80-m tower were used for evaluation of the model results and statistical analysis regarding the representativeness. Statistical characteristics of the observed and simulated data are analyzed. Physical downscaling of model <span class="hlt">wind</span> and downward shortwave flux at the ground surface was obtained, with consideration of the influence of topography, cloud cover, turbulence kinetic energy and other characteristics of the PBL. The results show that the temporal variance of shortwave flux is greater than that of the <span class="hlt">wind</span> power density, but the spatial variance of the <span class="hlt">wind</span> power density is much greater than that of the shortwave flux. Furthermore, the WRF results are compared with the Operational Multiscale Environment model with Grid Adaptivity (OMEGA) model results. Physical downscaling methods with different parameters are introduced and implemented. The representativeness of model results and observed data are discussed.</p> <div class="credits"> <p class="dwt_author">Jiang, J.; Koracin, D.; King, K. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">299</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19960021280&hterms=galvin&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgalvin"> <span id="translatedtitle">Composition of transient events in the <span class="hlt">solar</span> <span class="hlt">wind</span>: Ulysses/SWICS observations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The Ulysses mission covers an extensive data base which includes an in-ecliptic phase (Oct 1990 - Feb 1992), a southern hemisphere polar pass (with a southernmost point of 80 deg S heliographic latitude reached in Sept 1994). and a south to north transit passing through the ecliptic plane (March 1995). The <span class="hlt">Solar</span> <span class="hlt">Wind</span> Ion Composition Spectrometer measures <span class="hlt">solar</span> <span class="hlt">wind</span> ion composition, including charge state composition. for all types of <span class="hlt">solar</span> <span class="hlt">wind</span> flows. In-ecliptic measurements of the charge states of <span class="hlt">solar</span> <span class="hlt">wind</span> heavy ions in transient-related <span class="hlt">solar</span> <span class="hlt">wind</span>. such as <span class="hlt">solar</span> <span class="hlt">wind</span> associated with coronal mass c ejections (CMEs), typically indicate hotter than normal coronal temperatures. This distinction is not as prevalent for higher latitude observations. In this paper, we present temporal and latitudinal variations in the charge state composition of Oxygen, Silicon, and Iron for several transient-related <span class="hlt">solar</span> <span class="hlt">wind</span> events.</p> <div class="credits"> <p class="dwt_author">Galvin, A. B.; Cohen, C. M. S.; Gloeckler, G.; vonSteiger, R.; Geiss, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">300</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/6527375"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">wind</span> iron abundance variations at <span class="hlt">solar</span> <span class="hlt">wind</span> speeds > 600 km s/sup -1/, 1972 to 1976</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We have analyzed the Fe/H ratios in the peaks of high speed streams (HSS) during the decline of <span class="hlt">Solar</span> Cycle 20 and the following minimum (October 1972 to December 1976). We utilized the response of the 50 to 200 keV ion channel of the APL/JHU energetic particle experiment (EPE) onIMP-7 and 8 to <span class="hlt">solar</span> <span class="hlt">wind</span> iron ions at high <span class="hlt">solar</span> <span class="hlt">wind</span> speeds (V greater than or equal to 600 km sec/sup -1/), and compared our Fe measurements with <span class="hlt">solar</span> <span class="hlt">wind</span> H and He parameters from the Los Alamos National Laboratory (LANL) instruments on the same spacecraft. In general, the Fe distribution parameters (bulk velocity, flow direction, temperature) are found to be similar to the LANL He parameters. Although the average Fe/H ration in many steady HSS peaks agrees within observational uncertainties with the nominal coronal ratio of 4.7 x 10/sup -5/, abundance variations of a factor of up to 6 are obtained across a given coronal-hole associated HSS. There are, as well, factor of 2 variations between stream-averaged abundances for recurent HSS emanating from different coronal holes occurring on the sun on the same <span class="hlt">solar</span> rotation. flare-related <span class="hlt">solar</span> <span class="hlt">wind</span> streams sometimes show Fe/H ratios enhanced by factors of 4 to 5 over coronal-hole associated, quite time streams. Over the period 1973 to 1976, a steady decrease in the average quitetime Fe/H ratio by a ractor approx. 4 is measured on both IMP-7 and 8.</p> <div class="credits"> <p class="dwt_author">Mitchell, D.G.; Roelof, E.C.; Bame, S.J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_14");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" 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id="NextPageLink" onclick='return showDiv("page_17");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">301</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013xmm..prop...88G"> <span id="translatedtitle">Characterization of Heliospheric <span class="hlt">Solar</span> <span class="hlt">Wind</span> Charge Exchange</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We are performing a multi-year monitoring campaign of SWCX emission toward high latitude molecular clouds to measure and characterize the slowly varying heliospheric component, verify our models of the neutral gas distribution in the <span class="hlt">solar</span> system, and measure the charge exchange interaction cross-sections. The campaign includes data from both XMM and Suzaku. In particular, XMM data in the direction of the high latitude molecular cloud MBM12 are the longest temporal baseline data we have to track the SWCX emission over the full <span class="hlt">solar</span> cycle. The campaign includes data as far back as 2000, but lacks uniform coverage over time. In this proposal we request an additional pointing to improve our timeline and coverage.</p> <div class="credits"> <p class="dwt_author">Galeazzi, Massimiliano</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">302</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19960021403&hterms=power+spectrum+magnetic+field+fluctuations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpower%2Bspectrum%2Bmagnetic%2Bfield%2Bfluctuations"> <span id="translatedtitle">Alfvenic fluctuations in the <span class="hlt">solar</span> <span class="hlt">wind</span> observed by Ulysses</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">One of the striking results of the Sun's south polar pass by Ulysses was the discovery of large amplitude, long period Alfvenic fluctuations that were continuously present in the <span class="hlt">solar</span> <span class="hlt">wind</span> flow from the polar coronal hole. The fluctuations dominate the variances and power spectra at periods greater than or equal to 1 hour and are evident as correlated fluctuations in the magnetic field and <span class="hlt">solar</span> <span class="hlt">wind</span> velocity components. Various properties of the fluctuations in the magnetic field, in the velocity, and in the electric field have been established. The waves appear to have important implications for galactic cosmic rays and for the <span class="hlt">solar</span> <span class="hlt">wind</span>, topics which have continued to be investigated. Their origin is also under study, specifically whether or not they represent motions of the ends of the field lines at the Sun. The resolution of these issues has benefited from the more recent observations as the spacecraft traveled northward toward the ecliptic and passed into the northern <span class="hlt">solar</span> hemisphere. All these observations will be presented and their implications will be discussed.</p> <div class="credits"> <p class="dwt_author">Smith, E. J.; Neugebauer, M; Tsurutani, B. T.; Balogh, A.; McComas, D. J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">303</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/1037937"> <span id="translatedtitle">Western <span class="hlt">Wind</span> and <span class="hlt">Solar</span> Integration Study: Hydropower Analysis</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The U.S. Department of Energy's (DOE) study of 20% <span class="hlt">Wind</span> Energy by 2030 was conducted to consider the benefits, challenges, and costs associated with sourcing 20% of U.S. energy consumption from <span class="hlt">wind</span> power by 2030. This study found that with proactive measures, no insurmountable barriers were identified to meet the 20% goal. Following this study, DOE and the National Renewable Energy Laboratory (NREL) conducted two more studies: the Eastern <span class="hlt">Wind</span> Integration and Transmission Study (EWITS) covering the eastern portion of the U.S., and the Western <span class="hlt">Wind</span> and <span class="hlt">Solar</span> Integration Study (WWSIS) covering the western portion of the United States. The WWSIS was conducted by NREL and research partner General Electric (GE) in order to provide insight into the costs, technical or physical barriers, and operational impacts caused by the variability and uncertainty of <span class="hlt">wind</span>, photovoltaic, and concentrated <span class="hlt">solar</span> power when employed to serve up to 35% of the load energy in the WestConnect region (Arizona, Colorado, Nevada, New Mexico, and Wyoming). WestConnect is composed of several utility companies working collaboratively to assess stakeholder and market needs to and develop cost-effective improvements to the western wholesale electricity market. Participants include the Arizona Public Service, El Paso Electric Company, NV Energy, Public Service of New Mexico, Salt River Project, Tri-State Generation and Transmission Cooperative, Tucson Electric Power, Xcel Energy and the Western Area Power Administration.</p> <div class="credits"> <p class="dwt_author">Acker, T.; Pete, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">304</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21574692"> <span id="translatedtitle">A MODEL FOR THE SOURCES OF THE SLOW <span class="hlt">SOLAR</span> <span class="hlt">WIND</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Models for the origin of the slow <span class="hlt">solar</span> <span class="hlt">wind</span> must account for two seemingly contradictory observations: the slow <span class="hlt">wind</span> 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 <span class="hlt">wind</span> also has large angular width, up to {approx}60{sup 0}, 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 <span class="hlt">wind</span> 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 <span class="hlt">solar</span> <span class="hlt">wind</span>, and magnetic field for a time period preceding the 2008 August 1 total <span class="hlt">solar</span> 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 <span class="hlt">wind</span>. 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.</p> <div class="credits"> <p class="dwt_author">Antiochos, S. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Mikic, Z.; Titov, V. S.; Lionello, R.; Linker, J. A., E-mail: spiro.antiochos@nasa.gov [Predictive Science, Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-04-20</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">305</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20110007840&hterms=miki&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmiki"> <span id="translatedtitle">A Model for the Sources of the Slow <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Models for the origin of the slow <span class="hlt">solar</span> <span class="hlt">wind</span> must account for two seemingly contradictory observations: The slow <span class="hlt">wind</span> 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 <span class="hlt">wind</span> has large angular width, up to approximately 60 degrees, 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 <span class="hlt">wind</span> 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 front the heliospheric current sheet. We then use an MHD code and MIDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady <span class="hlt">solar</span> <span class="hlt">wind</span> and magnetic field for a time period preceding the August 1, 2008 total <span class="hlt">solar</span> 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 <span class="hlt">wind</span>. 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.</p> <div class="credits"> <p class="dwt_author">Antiochos, Spiro K.; Mikic, Z.; Titov, V. S.; Lionello, R.; Linker, J. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">306</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008cosp...37.3335V"> <span id="translatedtitle">Turbulent mixing of the <span class="hlt">solar</span> <span class="hlt">wind</span> with the interstellar medium</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We demonstrate both theoretically and using recent experimental data, that interaction of the <span class="hlt">solar</span> <span class="hlt">wind</span> with the interstellar medium is not laminar as supposed in many theoretical and numerical models, but essentially turbulent. Evidences favoring the latter scenario are based on "Voyager" spacecraft observations of plasma, magnetic field and energetic particle parameters, which are inconsistent with laminar theories. Inhomogeneous and time-variable <span class="hlt">solar</span> <span class="hlt">wind</span> streams often show variations with relative amplitudes of an order of one in magnetic fields, velocity, density, temperature and other plasma parameters at different time scales from minutes to years. This could bring to their non-linear submagnetosonic and supermagnetosonic interactions on the way in the heliosphere to its boundaries and beyond. The relative variations in energy and amount of supra-thermal and accelerated ions are orders of magnitude stronger. Another cause and free energy source of turbulent behavior with possible saw-tooth relaxation type oscillations at the boundary is due to instabilities of interacting <span class="hlt">solar</span> <span class="hlt">wind</span> and interstellar flows. As a consequence, the heliosphere should have a turbulent comet-like shape in the interstellar <span class="hlt">wind</span> what can be established only based on future measurements. Nevertheless, one can not expect any universal scaling here because of different ranges of dimensionless parameters suggesting non-steady state situation with not-fully developed inhomogeneous and intermittent turbulence. Possible indications are discussed on the existence of traveling perturbations in the interstellar medium influencing the outer heliosphere. This study was supported by the RFBR grants 07-02-00147, 06-05-64500, INTAS 03-51-6202 and MSU Interdisciplinary Scientific Project. It is also fulfilled as a part of the Programs of the Russian Academy of Sciences: "Origin and evolution of stars and galaxies" (P-04), "<span class="hlt">Solar</span> activity and physical processes in the Sun-Earth system" (P-16, Part 3) and "Plasma processes in the <span class="hlt">Solar</span> system" (OFN-16).</p> <div class="credits"> <p class="dwt_author">Veselovsky, Igor; Zeldovich, Maria; Verigin, Michael</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">307</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.2826Z"> <span id="translatedtitle">Twisted magnetic flux tubes in the <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Magnetic flux tubes in the <span class="hlt">solar</span> <span class="hlt">wind</span> can be twisted as they are transported from the <span class="hlt">solar</span> surface, where the tubes are twisted owing to photospheric motions. The twisted magnetic tubes can be detected as the variation of total (thermal+magnetic) pressure during their passage through observing satellite. The twist of isolated magnetic tube may explain the observed abrupt changes of magnetic field direction at tube walls. For the tubes aligned with the Parker spiral, the twist angle can be estimated from the change of magnetic field direction. The twisted tubes are unstable to kink instability when the twist exceeds a critical value. It is shown that the critical twist angle of the tube with a homogeneous twist is 70 degree, but the angle can be decreased owing to the motion of the tube with regards to the <span class="hlt">solar</span> <span class="hlt">wind</span> stream. Tangential velocity discontinuity near the boundaries of individual tubes may also result in the Kelvin-Helmholtz instability. It is shown that the axial magnetic field stabilizes the instability in the case of sub-Alfvenic speeds. But even small twist in the external magnetic field allows the Kelvin-Helmholtz instability to be developed for any speed. Therefore, twisted magnetic flux tubes can be unstable to Kelvin-Helmholtz instability when they move with small speed relative to main <span class="hlt">solar</span> <span class="hlt">wind</span> stream. The Kelvin-Helmholtz vortices may significantly contribute into the <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement N 313038/STORM and from the Austrian 'Fonds zur Förderung der wissenschaftlichen Forschung' under project P24740-N27.</p> <div class="credits"> <p class="dwt_author">Zaqarashvili, Teimuraz; Voros, Zoltan; Zhelyazkov, Ivan; Narita, Yasuhito; Bruno, Roberto</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">308</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19830033896&hterms=solar+radiation+abundance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsolar%2Bradiation%2Babundance"> <span id="translatedtitle">Probing the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration region using spectroscopic techniques</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Recent developments in the use of UV and EUV coronagraphic spectroscopy for studying the physical conditions in the <span class="hlt">solar</span> corona in the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration region from a heliocentric distance of 1.8 <span class="hlt">solar</span> radii out to 8 <span class="hlt">solar</span> radii and beyond are reviewed. Particular attention is given to theoretical considerations and techniques for the estimation of particle ionization balances and velocity distributions, coronal temperatures, neutral hydrogen, proton, electron and ion temperatures and densities, outflow velocities, charge states and chemical abundances from spectral line radiation and white-light measurements. Observational considerations are discussed as they relate to requirements for stray light rejection and the effects of geocorona and interplanetary dust emission in coronagraph design. Results of coronal H I Lyman alpha and white light observations made during sounding rocket flights are summarized, and future observational programs making use of rocket-borne instruments, Detached Shuttle Payload Flights, Spacelab or space platforms are indicated.</p> <div class="credits"> <p class="dwt_author">Withbroe, G. L.; Kohl, J. L.; Weiser, H.; Munro, R. H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">309</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19960021368&hterms=geometry+Solar&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgeometry%2BSolar"> <span id="translatedtitle">Self consistent MHD modeling of the <span class="hlt">solar</span> <span class="hlt">wind</span> from coronal holes with distinct geometries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Utilizing an iterative scheme, a self-consistent axisymmetric MHD model for the <span class="hlt">solar</span> <span class="hlt">wind</span> has been developed. We use this model to evaluate the properties of the <span class="hlt">solar</span> <span class="hlt">wind</span> issuing from the open polar coronal hole regions of the Sun, during <span class="hlt">solar</span> minimum. We explore the variation of <span class="hlt">solar</span> <span class="hlt">wind</span> parameters across the extent of the hole and we investigate how these variations are affected by the geometry of the hole and the strength of the field at the coronal base.</p> <div class="credits"> <p class="dwt_author">Stewart, G. A.; Bravo, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">310</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20110023419&hterms=Aurora&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAurora"> <span id="translatedtitle"><span class="hlt">Solar</span> Rotational Periodicities and the Semiannual Variation in the <span class="hlt">Solar</span> <span class="hlt">Wind</span>, Radiation Belt, and Aurora</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The behavior of a number of <span class="hlt">solar</span> <span class="hlt">wind</span>, radiation belt, auroral and geomagnetic parameters is examined during the recent extended <span class="hlt">solar</span> minimum and previous <span class="hlt">solar</span> cycles, covering the period from January 1972 to July 2010. This period includes most of the <span class="hlt">solar</span> minimum between Cycles 23 and 24, which was more extended than recent <span class="hlt">solar</span> minima, with historically low values of most of these parameters in 2009. <span class="hlt">Solar</span> rotational periodicities from S to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005 -2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the <span class="hlt">solar</span> cycle, when HSS are the predominant <span class="hlt">solar</span> <span class="hlt">wind</span> structures. There were minima in the amplitudes of all <span class="hlt">solar</span> rotational periodicities near the end of each <span class="hlt">solar</span> minimum, as well as at the start of the reversal of the <span class="hlt">solar</span> magnetic field polarity at <span class="hlt">solar</span> maximum (approx.1980, approx.1990, and approx. 2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995-1997 <span class="hlt">solar</span> minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the <span class="hlt">solar</span> <span class="hlt">wind</span>-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27 -day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the > 2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods, showing that processes in the magnetosphere act as a low-pass filter between the <span class="hlt">solar</span> <span class="hlt">wind</span> and the radiation belt. The A(sub p)/K(sub p) magnetic currents observed at subauroral latitudes are sensitive to proton auroral precipitation, especially for 9-day and shorter periods, while the A(sub p)/K(sub p) currents are governed by electron auroral precipitation for 13.5- and 27-day periodicities.</p> <div class="credits"> <p class="dwt_author">Emery, Barbara A.; Richardson, Ian G.; Evans, David S.; Rich, Frederick J.; Wilson, Gordon R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">311</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EPSC....8..345B"> <span id="translatedtitle">Gullies and the <span class="hlt">latitude</span> <span class="hlt">dependant</span> mantle: comparing Terra Cimmeria & Argyre Planitia</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">"Follow the water" has been an important theme for exploration of Mars. Under current atmospheric conditions, liquid water is only metastable at the surface. Using high-resolution images of Mars, we see kilometer-scale features with an alcove, channel and a debris apron - "gullies". These gullies resemble water-carved steepland channels on Earth [1, 12]. Previous global-scale studies covering both hemispheres of Mars have been conducted [2, 8-10], but using datasets with limited coverage, but as highresolution coverage of the planet continues to grow, full-coverage, global-scale studies become possible. Previous work has shown that gullies are common in the mid-latitudes and show variation in slope-face orientation with respect to latitude [2,9-11]. The variations in orientation are suggested to result from obliquity driven climate change [7], whereby when Mars' axial tilt is large, the average daytime temperatures are sufficient for melting of nearsurface ice to occur. Previous work [4, 14] has suggested that gullies may originate from the melting of a surface unit known as <span class="hlt">latitude-dependent</span> mantle (LDM). LDM is interpreted to be rich in ice and dust and was deposited during previous glacial epochs [14]. The method by which gullies form, their associations to LDM and relations to recent ice ages are still under debate. We will analyze the relationship between gullies and LDM by comparing two regions: (1) Terra Cimmeria where gullies are not always associated with the LDM and (2) Argyre Planitia, where gullies are almost always associated with the LDM [6]. We will compare gullydistribution, orientation, and topographic properties (e.g. slope) between these areas. Here we report on the first results: the Terra Cimmeria study.</p> <div class="credits"> <p class="dwt_author">Britton, A.; Conway, S. J.; Balme, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">312</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1998JGR...103.6495M"> <span id="translatedtitle">Dynamical age of <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence in the outer heliosphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In an evolving turbulent medium, a natural timescale can be defined in terms of the energy decay time. The time evolution may be complicated by other effects such as energy supply due to driving, and spatial inhomogeneity. In the <span class="hlt">solar</span> <span class="hlt">wind</span> the turbulence appears not to be simply engaging in free decay, but rather the energy level observed at a particular position in the heliosphere is affected by expansion, 'mixing', and driving by stream shear. Here we discuss a new approach for estimating the 'age' of <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence as a function of heliocentric distance, using the local turbulent decay rate as the natural clock, but taking into account expansion and driving effects. The simplified formalism presented here is appropriate to low cross helicity turbulence in the outer heliosphere especially at low heliolatitudes. We employ Voyager data to illustrate our method, which improves upon the familiar estimates in terms of local eddy turnover times.</p> <div class="credits"> <p class="dwt_author">Matthaeus, William H.; Smith, Charles W.; Oughton, Sean</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">313</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://arxiv.org/pdf/0709.4505v1"> <span id="translatedtitle">The <span class="hlt">Solar</span> <span class="hlt">Wind</span> Around Pluto (SWAP) Instrument Aboard New Horizons</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">The <span class="hlt">Solar</span> <span class="hlt">Wind</span> Around Pluto (SWAP) instrument on New Horizons will measure the interaction between the <span class="hlt">solar</span> <span class="hlt">wind</span> and ions created by atmospheric loss from Pluto. These measurements provide a characterization of the total loss rate and allow us to examine the complex plasma interactions at Pluto for the first time. Constrained to fit within minimal resources, SWAP is optimized to make plasma-ion measurements at all rotation angles as the New Horizons spacecraft scans to image Pluto and Charon during the flyby. In order to meet these unique requirements, we combined a cylindrically symmetric retarding potential analyzer (RPA) with small deflectors, a top-hat analyzer, and a redundant/coincidence detection scheme. This configuration allows for highly sensitive measurements and a controllable energy passband at all scan angles of the spacecraft.</p> <div class="credits"> <p class="dwt_author">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</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-09-27</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">314</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://arxiv.org/pdf/1108.6072v1"> <span id="translatedtitle">Residual energy in magnetohydrodynamic turbulence and in the <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Recent observations indicate that kinetic and magnetic energies are not in equipartition in the <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence. Rather, magnetic fluctuations are more energetic and have somewhat steeper energy spectrum compared to the velocity fluctuations. This leads to the presence of the so-called residual energy E_r=E_v-E_b in the inertial interval of turbulence. This puzzling effect is addressed in the present paper in the framework of weak turbulence theory. Using a simple model of weakly colliding Alfv\\'en waves, we demonstrate that the kinetic-magnetic equipartition indeed gets broken as a result of nonlinear interaction of Alfv\\'en waves. We establish that magnetic energy is indeed generated more efficiently as a result of these interactions, which proposes an explanation for the <span class="hlt">solar</span> <span class="hlt">wind</span> observations.</p> <div class="credits"> <p class="dwt_author">Stanislav Boldyrev; Jean Carlos Perez; Vladimir Zhdankin</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-08-30</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">315</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19760024031&hterms=melbourne+fl+radiation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmelbourne%2Bfl%2Bradiation"> <span id="translatedtitle">Mass fractionation of the lunar surface by <span class="hlt">solar</span> <span class="hlt">wind</span> sputtering</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The sputtering of the lunar surface by the <span class="hlt">solar</span> <span class="hlt">wind</span> is examined as a possible mechanism of mass fractionation. Simple arguments based on current theories of sputtering and the ballistics of the sputtered atoms suggest that most ejected atoms will have sufficiently high energy to escape lunar gravity. However, the fraction of atoms which falls back to the surface is enriched in the heavier atomic components relative to the lighter ones. This material is incorporated into the heavily radiation-damaged outer surfaces of grains where it is subject to resputtering. Over the course of several hundred years an equilibrium surface layer, enriched in heavier atoms, is found to form. The dependence of the calculated results upon the sputtering rate and on the details of the energy spectrum of sputtered particles is investigated. It is concluded that mass fractionation by <span class="hlt">solar</span> <span class="hlt">wind</span> sputtering is likely to be an important phenomenon on the lunar surface.</p> <div class="credits"> <p class="dwt_author">Switkowski, Z. E.; Haff, P. K.; Tombrello, T. A.; Burnett, D. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1975-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">316</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19740049588&hterms=helium+effusion&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dhelium%2Beffusion"> <span id="translatedtitle">The lunar atmosphere. [noble gas composition and <span class="hlt">solar</span> <span class="hlt">wind</span> effects</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">In contrast to the earth's atmosphere, the atmosphere of the moon is exceedingly tenuous and appears to consist mainly of noble gases. The <span class="hlt">solar</span> <span class="hlt">wind</span> impinges on the lunar surface, supplying detectable amounts of helium, neon and Ar-36. Influxes of <span class="hlt">solar</span> <span class="hlt">wind</span> protons and carbon and nitrogen ions are significant, but atmospheric gases containing these elements have not been positively identified. Radiogenic Ar-40 and Rn-222 produced within the moon have been detected. The present rate of effusion of argon from the moon accounts for about 0.4% of the total production of Ar-40 due to decay of K-40 if the average abundance of potassium in the moon is 1000 ppm. Lack of weathering processes in the regolith suggests that most of the atmospheric Ar-40 originates deep in the lunar interior, perhaps in a partially molten core. If so, other gases may be vented along with the argon.</p> <div class="credits"> <p class="dwt_author">Hodges, R. R., Jr.; Hoffman, J. H.; Johnson, F. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1974-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">317</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013MS%26E...52g2003C"> <span id="translatedtitle">A desalination plant with <span class="hlt">solar</span> and <span class="hlt">wind</span> energy</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The shortage of freshwater resources has become a worldwide problem. China has a water shortage, although the total amount of water resources is the sixth in the world, the per capita water capacity is the 121th (a quarter of the world's per capita water capacity), and the United Nations considers China one of the poorest 13 countries in the world in terms of water. In order to increase the supply of fresh water, a realistic way is to make full use of China's long and narrow coastline for seawater desalination. This paper discusses a sea water desalination device, the device adopts distillation, uses the greenhouse effect principle and <span class="hlt">wind</span> power heating principle, and the two-type start is used to solve the problem of vertical axis <span class="hlt">wind</span> turbine self-starting. Thrust bearings are used to ensure the stability of the device, and to ensure absorbtion of <span class="hlt">wind</span> energy and <span class="hlt">solar</span> energy, and to collect evaporation of water to achieve desalination. The device can absorb <span class="hlt">solar</span> and <span class="hlt">wind</span> energy instead of input energy, so it can be used in ship, island and many kinds of environment. Due to the comprehensive utilization of <span class="hlt">wind</span> power and <span class="hlt">solar</span> power, the efficiency of the device is more than other passive sea water desalting plants, the initial investment and maintenance cost is lower than active sea water desalting plant. The main part of the device cannot only be used in offshore work, but can also be used in deep sea floating work, so the device can utilise deep sea energy. In order to prove the practicability of the device, the author has carried out theory of water production calculations. According to the principle of conservation of energy, the device ais bsorbing <span class="hlt">solar</span> and <span class="hlt">wind</span> power, except loose lost part which is used for water temperature rise and phase transition. Assume the inflow water temperature is 20 °C, outflow water temperature is 70 °C, the energy utilization is 60%, we can know that the water production quantity is 8 kg/ m2 per hour. Comparing with the disk <span class="hlt">solar</span> distillation apparatus, of which water production quantity is only 3-4kg/m2 per hour only in sunny day, but can't be used at night, the water production quantity is highly increased. So the device should have a good application prospect.</p> <div class="credits"> <p class="dwt_author">Chen, H.; Ye, Z.; Gao, W.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">318</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/ja/v085/iA13/JA085iA13p07715/JA085iA13p07715.pdf"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">wind</span> flow past Venus - Theory and comparisons</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Advanced computational procedures are applied to an improved model of <span class="hlt">solar</span> <span class="hlt">wind</span> 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</p> <div class="credits"> <p class="dwt_author">J. R. Spreiter; Stephen S. Stahara</p> <p class="dwt_publisher"></p> <p class="publishDate">1980-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">319</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/42040524"> <span id="translatedtitle">Venus-like interaction of the <span class="hlt">solar</span> <span class="hlt">wind</span> with Mars</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The magnetometer and electron reflectometer experiment (MAG\\/ER) on the Mars Global Surveyor (MGS) spacecraft has obtained magnetic field and electron data which indicates that the <span class="hlt">solar</span> <span class="hlt">wind</span> interaction with Mars is primarily an ionospheric-atmospheric interaction similar to that at Venus. However, the global-scale electric currents and resulting magnetic fields due to the interaction at Mars are locally interrupted or perturbed</p> <div class="credits"> <p class="dwt_author">C. C. Law; D. H. Crider; P. W. Walker; Y. Chen; M. H. Acuña; J. E. P. Connerney; R. P. Lin; K. A. Anderson; D. L. Mitchell; C. W. Carlson; J. McFadden; D. A. Brain; H. Rème; C. Mazelle; J. A. Sauvaud; C. d'Uston; D. Vignes; S. J. Bauer; N. F. Ness</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">320</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/44282176"> <span id="translatedtitle">Manifestation of the 399-day variations in <span class="hlt">solar</span> <span class="hlt">wind</span> parameters</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Based on a large series (N = 14 038) of daily <span class="hlt">solar</span> <span class="hlt">wind</span> densities, we obtained the fluctuation power spectrum. The spectrum shows that the 399-day\\u000a variation (the synodic period of Jupiter) has the largest amplitude in the interval of periods from 20 to 800 days. It is\\u000a second in magnitude only to the secular, 22-, and 11-year variations. The</p> <div class="credits"> <p class="dwt_author">N. G. Skryabin; V. E. Timofeev; L. I. Miroshnichenko; S. N. Samsonov</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_15");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">321</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://faculty.olin.edu/~jtownsend/Renewable%20Fall%202006/docs/andrew%27s%20article.pdf"> <span id="translatedtitle">Performance evaluation of hybrid (<span class="hlt">wind\\/solar</span>\\/diesel) power systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Depleting oil and gas reserves, combined with the growing concerns of global warming, have made it inevitable to seek alternative\\/renewable energy sources. The integration of renewables such as <span class="hlt">solar</span> and <span class="hlt">wind</span> energy is becoming increasingly attractive and is being used widely, for substitution of oil-produced energy, and eventually to minimize atmospheric degradation. The literature shows that commercial\\/residential buildings in Saudi</p> <div class="credits"> <p class="dwt_author">M. A. Elhadidy</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">322</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/jz/v071/i019/JZ071i019p04469/JZ071i019p04469.pdf"> <span id="translatedtitle">Mariner 2 Observations of the <span class="hlt">Solar</span> <span class="hlt">Wind</span>, 1, Average Properties</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper summarizes the properties of the positive-ion component of the <span class="hlt">solar</span> <span class="hlt">wind</span> observed during the four months of the Mariner 2 flight to and past Venus in 1962. The protons' average velocity and temperature were approximately 500 km\\/sec and 1.7 X 105øK, respectively. Several streams of hot, high-velocity plasma were observed to recur at 27-day intervals, with peak velocity</p> <div class="credits"> <p class="dwt_author">Marcia Neugebauer; Conway W. Snyder</p> <p class="dwt_publisher"></p> <p class="publishDate">1966-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">323</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/jz/v069/i007/JZ069i007p01181/JZ069i007p01181.pdf"> <span id="translatedtitle">Deformation of the Geomagnetic Field by the <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">From the three-dimensional numerical solution to the Chapman-Ferraro prob- lem of a steady <span class="hlt">solar</span> <span class="hlt">wind</span> perpendicularly incident upon a dipole field, a simple spherical harmonic description of the distorted field is obtained. From this, a three-dimensional picture of the field line configuration within the magnetosphere is given. The field lines are found to be compressed on both the daytime and</p> <div class="credits"> <p class="dwt_author">Gilbert D. Mead</p> <p class="dwt_publisher"></p> <p class="publishDate">1964-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">324</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014cosp...40E2435P"> <span id="translatedtitle">OMNI: A Description of Near-Earth <span class="hlt">Solar</span> <span class="hlt">Wind</span> Environment</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">OMNI is an hourly resolution multi-source data set of near-Earth <span class="hlt">solar</span> <span class="hlt">wind</span>'s magnetic field and plasma parameters spanning the period from November 1963 (IMP 1 launch) to today, and it is being updated regularly with new data. OMNI is widely used in the heliospheric community as is documented by the large number of acknowledgements in scientific papers. OMNI provides the IMF (magnitude and vector), flow velocity (magnitude and vector), flow pressure, proton density, alpha particle to proton density ratio, and several additional parameters including sunspot and geomagnetic indices and energetic proton fluxes from IMP and GOES. Spacecraft data used for compiling the OMNI <span class="hlt">solar</span> <span class="hlt">wind</span> reference include IMP-8, ACE, <span class="hlt">Wind</span>, ISEE-3, and Geotail. The data from ISEE-3, <span class="hlt">Wind</span>, and ACE were time-shifted because they are about an hour upstream of the Earth's magnetosphere. Extensive quality control and cross- comparisons of overlapping data sets were made in creating OMNI. This presentation will describe the OMNI data set and highlight its wide use in the space science community. We will also present some of the many capabilities of the OMNIweb interface (http://omniweb.gsfc.nasa.gov/ow.html) that provides access to the entire OMNI data set. OMNIWeb allows users to generate plots vs. time, to create scatter plots of any two OMNI parameters, to filter with user-specified parameter range criteria, to list and download OMNI parameters, to generate distributions of OMNI parameter values, and to browse and retrieve a static (but periodically updated) daily-resolution IMF polarity plot covering the entire OMNI time span. The Omni data set represents a thorough description of various characteristics of near-Earth <span class="hlt">solar</span> <span class="hlt">wind</span> magnetic field and plasma, which could be used as a basis for that space environment's standard.</p> <div class="credits"> <p class="dwt_author">Papitashvili, Natasha; Bilitza, Dieter; King, Joseph</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">325</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/FR-2010-09-27/pdf/2010-24064.pdf"> <span id="translatedtitle">75 FR 59291 - In the Matter of: Certain <span class="hlt">Wind</span> and <span class="hlt">Solar</span>-Powered Light Posts and Street Lamps; Notice of...</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013</a></p> <p class="result-summary">...Matter of: Certain <span class="hlt">Wind</span> and <span class="hlt">Solar</span>-Powered Light Posts and Street Lamps; Notice of Investigation...importation of certain <span class="hlt">wind</span> and <span class="hlt">solar</span>-powered light posts and street lamps by reason of infringement...and <span class="hlt">solar</span>- [[Page 59292</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2010-09-27</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">326</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19790018882&hterms=studio+13&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dstudio%2B13"> <span id="translatedtitle">Magnetic dips in the <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Using magnetic data from the HELIOS 1 fluxgate magnetometer, with a 0.2 sec resolution, the structures of several interplanetary discontinuities involving magnetic dips and rotations of the magnetic field vector were investigated. A minimum variance analysis illustrates the behavior of the magnetic field through the transition in the plane of its maximum variation. Using this analysis, quite different structures have been individuated and, in particular, narrow transitions resembling almost one dimensional reconnected neutral sheets. For the thinner cases (scale lengths of the magnetic rotation of the order or smaller than 1,000 km), results show the observed structures could be the nonlinear effect of a resistive tearing mode instability having developed on an originally one dimensional neutral sheet at the <span class="hlt">solar</span> corona.</p> <div class="credits"> <p class="dwt_author">Dobrowolny, M.; Bavassano, B.; Mariani, F.; Ness, N.; Burlaga, L. F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1978-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">327</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUSMSH53C..03G"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">wind</span> dynamics in the ascending phase of the <span class="hlt">solar</span> cycle: five spacecraft observations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We combined observations from: Helios 1 and 2, IMP-8, Voyager 1 and 2, from November 1977 to February 1978 (ascending phase of <span class="hlt">solar</span> cycle 21). We identified five Corotating Interaction Regions, five Interplanetary Coronal Mass Ejections, and produced maps of large-scale features unifying and summarizing the data. We discuss their characteristics to illuminate some aspects of the <span class="hlt">solar</span> <span class="hlt">wind</span> dynamics, based on this unique data set, during the ascending phase of the cycle.</p> <div class="credits"> <p class="dwt_author">Gonzalez-Esparza, A.; Romero-Hernandez, E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">328</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19810048926&hterms=conic+section&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dconic%2Bsection"> <span id="translatedtitle">The Venus ionosphere as an obstacle to the <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Pioneer Venus Orbiter Electron Temperature Probe measurements of hundreds of bow shock and ionopause crossings are employed in describing the configuration of these two boundaries and their variations in response to changes in <span class="hlt">solar</span> <span class="hlt">wind</span> pressure. The average bow shock configuration is found to be well represented by an Archimedian hyperboloid whose altitude at the subsolar point is 0.46 Venus radii, a value slightly greater than that derived from Pioneer Venus magnetometer data using a fit to a general conic section. It is noted that the average bow shock configuration exhibits a high degree of azimuthal symmetry near the terminator. The orbit to orbit variability of the shock location is unexpectedly large, the standard deviation being about 10%. A tendency is noted for the bow shock and the ionopause to expand and contract simultaneously, but the weakness of their orbit by orbit correlation suggests that the ionopause of Venus is not the only obstacle to the <span class="hlt">solar</span> <span class="hlt">wind</span>. It is thought that such processes as photoion pickup and charge exchange with neutrals may be important in diverting the <span class="hlt">solar</span> <span class="hlt">wind</span> plasma around the planet.</p> <div class="credits"> <p class="dwt_author">Theis, R. F.; Brace, L. H.; Schatten, K. H.; Russell, C. T.; Slavin, J. A.; Wolfe, J. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">329</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012PhRvL.109w1102R"> <span id="translatedtitle">Construction of <span class="hlt">Solar-Wind</span>-Like Magnetic Fields</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Fluctuations in the <span class="hlt">solar</span> <span class="hlt">wind</span> fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the “random” character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the <span class="hlt">solar</span> <span class="hlt">wind</span>, as well as with the distribution of the angles of rapid changes (“discontinuities”), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence and of the propagation of energetic particles.</p> <div class="credits"> <p class="dwt_author">Roberts, D. Aaron</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">330</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFMSM23A2233L"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">wind</span> dynamic pressure effect on global auroral intensity</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Previous studies have shown that the night side proton aurora varies closely with <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure. These findings were based on single events, when the geomagnetic activity otherwise was low (positive Bz). We present a statistical analysis showing that much of the variation in proton aurora intensity can be explained by a function combining <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure and the ring current index SYM-H. Filtering out images from the known substorms in the IMAGE FUV dataset has little or no effect on the correlation. Using this dataset, we can also compare the proton aurora intensity (observed by the SI-12 camera) to the electron-dominated aurora, which appears less correlated with the <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure. We discuss the findings in terms of various proposed mechanisms: A more field-aligned pitch angle distribution resulting from magnetospheric compression, EMIC wave growth during magnetospheric compression, pitch angle scattering in a stretched tail configuration, and increased magnetospheric convection. In addition we investigate the effect on auroral intensity of different low altitude magnetic field strengths (the non-dipole terms of the International Geomagnetic Reference Field), and variations in thermospheric density.</p> <div class="credits"> <p class="dwt_author">Laundal, K.; Ostgaard, N.; Reistad, J. P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">331</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23368180"> <span id="translatedtitle">Construction of <span class="hlt">solar-wind</span>-like magnetic fields.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Fluctuations in the <span class="hlt">solar</span> <span class="hlt">wind</span> fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the "random" character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the <span class="hlt">solar</span> <span class="hlt">wind</span>, as well as with the distribution of the angles of rapid changes ("discontinuities"), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence and of the propagation of energetic particles. PMID:23368180</p> <div class="credits"> <p class="dwt_author">Roberts, D Aaron</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">332</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19730056699&hterms=bennett&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dbennett"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">wind</span> interaction with Comet Bennett /1969i/.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Examination of the relations between the <span class="hlt">solar-wind</span> and Comet Bennett during the period from Mar. 23 to Apr. 5, 1970. A large kink was observed in the ion tail of the comet on April 4, but no <span class="hlt">solar-wind</span> stream was observed in the ecliptic plane which could have caused the kink. Thus, either there was no correlation between the <span class="hlt">solar</span> <span class="hlt">wind</span> 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 March 24 and March 28, but again no effect was seen in photographs of the Comet.</p> <div class="credits"> <p class="dwt_author">Burlaga, L. F.; Donn, B.; Neugebauer, M.; Rahe, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1973-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">333</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..12.3566G"> <span id="translatedtitle">Statistical properties of <span class="hlt">solar</span> <span class="hlt">wind</span> discontinuities and intermittent turbulence</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Recent studies have compared properties of the magnetic field in simulations of Hall MHD turbulence with spacecraft data, focusing on methods used to identify classical discontinuities and intermittency statistics. Comparison of ACE <span class="hlt">solar</span> <span class="hlt">wind</span> data and simulations of 2D and 3D turbulence shows good agreement in waiting-time analysis of magnetic discontinuities, and in the related distribution of magnetic field increments. The discontinuities are not distributed without correlations, but rather they show non-Poisson correlations, possibly in the form of burstiness or voids, present in the data at least up to the typical correlation scale. A similar conclusion emerges from Poisson analysis of the simulation dataset. Our tentative conclusion is that Poisson's random noise might well characterize the very large scale <span class="hlt">solar</span> <span class="hlt">wind</span> fluctuations. However in the inertial range (scales of few hours in the spacecraft frame) the analysis suggests the presence of correlations, and the waiting times between events display an associated bursty character. This supports the viewpoint that <span class="hlt">solar</span> <span class="hlt">wind</span> turbulent fluctuations at least in part are related to the presence of large structures of highly conducting plasma. The discontinuities or bursty coherent structures represent in this view the current sheets that form between magnetic flux tubes which may be a signature of intermittent, anisotropic, fully developed MHD turbulence. Some of these current sheets could be reconnection sites. We're finding a way to identify the reconnection regions with high reconnection rate, as a subset of these current sheets.</p> <div class="credits"> <p class="dwt_author">Greco, Antonella; Servidio, Sergio; Matthaeus, William H.; Dmitruk, Pablo</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">334</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.6899D"> <span id="translatedtitle">Study of <span class="hlt">solar</span> <span class="hlt">wind</span> spectra by nonlinear waves interaction</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The nature of small-scale turbulent fluctuations in the <span class="hlt">solar</span> <span class="hlt">wind</span> (SW) turbulence is a topic that is being investigated extensively nowadays, both theoretically and observationally. Although recent observations predict the evidence of the dominance of kinetic Alfvén waves (KAW) at sub-ion scales with frequency below than ion cyclotron frequency, while other studies suggest that the KAW mode cannot carry the turbulence cascade down to electron scales and that the whistler mode is more relevant. In the present work, nonlinear interaction of kinetic Alfvén wave with whistler wave is considered as one of the possible cause responsible for the <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence. A set of coupled dimensionless equations are derived for the intermediate beta plasmas and the nonlinear interaction between these two wave modes has been studied. As a consequence of ponderomotive nonlinearity, the pump KAW becomes filamented when its power exceeds the threshold for the filamentation instability. Whistler is considered to be weak and thus doesn't have enough intensity to initiate its own localization. It gets localized while propagating through the density channel created by KAW localization. In addition, spectral scales of power spectra of KAW and whistler are also calculated. The steeper spectra are found with scaling greater than -5/3. This type of nonlinear interaction between different wave modes and steeper spectra is one of the reasons for the <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence and particles acceleration. This work is partially supported by DST (India) and FP7/STORM (313038)</p> <div class="credits"> <p class="dwt_author">Dwivedi, Navin; Sharma, Rampal; Narita, Yasuhito</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">335</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EPJST.223.2637T"> <span id="translatedtitle">Kolmogorov spectrum of renewable <span class="hlt">wind</span> and <span class="hlt">solar</span> power fluctuations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">With increasing the contribution of renewable energies in power production, the task of reducing dynamic instability in power grids must also be addressed from the generation side, because the power delivered from such sources is spatiotemporally stochastic in nature. Here we characterize the stochastic properties of the <span class="hlt">wind</span> and <span class="hlt">solar</span> energy sources by studying their spectrum and multifractal exponents. The computed power spectrum from high frequency time series of <span class="hlt">solar</span> irradiance and <span class="hlt">wind</span> power reveals a power-law behaviour with an exponent ˜ 5/3 (Kolmogorov exponent) for the frequency domain 0.001 Hz < f < 0.05 Hz, which means that the power grid is being fed by turbulent-like sources. Our results bring important evidence on the stochastic and turbulent-like behaviour of renewable power production from <span class="hlt">wind</span> and <span class="hlt">solar</span> energies, which can cause instability in power grids. Our statistical analysis also provides important information that must be used as a guideline for an optimal design of power grids that operate under intermittent renewable sources of power.</p> <div class="credits"> <p class="dwt_author">Tabar, M. Reza Rahimi; Anvari, M.; Lohmann, G.; Heinemann, D.; Wächter, M.; Milan, P.; Lorenz, E.; Peinke, Joachim</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">336</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.P13C1951P"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">Wind</span> Driven Plasma Fluxes from the Venus Ionosphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">SOLAR</span> <span class="hlt">WIND</span> DRIVEN PLASMA FLUXES FROM THE VENUS IONOSPHERE H. Pérez-de-Tejada (1), R. Lundin (2), H. Durand-Manterola (1), S. Barabash (2), T. L. Zhang (3), J. A., Sauvaud (4), and M. Reyes-Ruiz (5) 1 - Institute of Geophysics, UNAM, México, D. F. 2 - Swedish Institute of Space Physics, Kiruna, Sweden 3 - Space Research Institute, Graz, Austria 4 - CESR, Toulouse, France 5 - Institute of Astronomy, UNAM, Ensenada, México Measurements conducted with the ASPERA-4 instrument and the magnetometer of the Venus Express spacecraft show that the kinetic pressure of planetary O+ ion fluxes measured in the Venus wake can be significantly larger than the local magnetic pressure and, as a result, those ions are not being driven by magnetic forces but by the kinetic energy of the <span class="hlt">solar</span> <span class="hlt">wind</span>. Beams of planetary O+ ions with those properties have been detected in several orbits of the Venus Express through the wake as the spacecraft traverses by the noon-midnight plane along its near polar trajectory. The momentum flux of the O+ ions leads to superalfvenic flow conditions. It is suggested that such O+ ion beams are produced in the vicinity of the magnetic polar regions of the Venus ionosphere where the <span class="hlt">solar</span> <span class="hlt">wind</span> erodes the local plasma leading to plasma channels that extend downstream from those regions.</p> <div class="credits"> <p class="dwt_author">Perez De Tejada, H. A.; Lundin, R. N.; Zhang, T.; Sauvaud, J. A.; Reyes-Ruiz, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">337</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMSH13A2230P"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">wind</span> strahl broadening by self-generated Langmuir waves</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">solar</span> <span class="hlt">wind</span> strahl consists of a field aligned population of electrons ubiquitous in <span class="hlt">solar</span> <span class="hlt">wind</span> particle measurements in the energy range of about 50 eV to 1 keV. While the strahl field aligned focusing characteristic due to the large scale magnetic mirror force is not controversial, the nature of its relatively broad angular distribution is still in debate. Here we report numerical simulations on kinetic quasi-linear wave-particle interaction, which account for the analytical solution of the equilibrium electron distribution supporting the observed broad width strahl feature. It is found that Langmuir fluctuations are unstable in the presence of the strahl component, and that the ensuing wave-particle diffusion leads to significant angular broadening of the strahl. The present theory represents an alternative or complementary mechanism to the usual whistler diffusion, and the results suggest that self-induced Langmuir waves might play a key role in the understanding of the broadening of the <span class="hlt">solar</span> <span class="hlt">wind</span> strahl.</p> <div class="credits"> <p class="dwt_author">Pavan, J.; Figueroa-Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">338</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/61317867"> <span id="translatedtitle">A self-contained weather station for <span class="hlt">wind</span> and <span class="hlt">solar</span> energy prospecting</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The collection of meteorological data for <span class="hlt">wind</span> and <span class="hlt">solar</span> energy studies has been facilitated through the development of electronic weather stations. The Weather Wizard is a microprocessor controlled weather station which can be programmed for specialized applications such as <span class="hlt">wind</span> and <span class="hlt">solar</span> energy resource assessment. Use of the Weather Wizard during a recent <span class="hlt">wind</span> energy related project is discussed.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">339</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60711507"> <span id="translatedtitle">Transmission Benefits of Co-Locating Concentrating <span class="hlt">Solar</span> Power and <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In some areas of the U.S. transmission constraints are a limiting factor in deploying new <span class="hlt">wind</span> and concentrating <span class="hlt">solar</span> power (CSP) plants. Texas is an example of one such location, where the best <span class="hlt">wind</span> and <span class="hlt">solar</span> resources are in the western part of the state, while major demand centers are in the east. The low capacity factor of <span class="hlt">wind</span> is</p> <div class="credits"> <p class="dwt_author">R. Sioshansi; P. Denholm</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">340</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.nrel.gov/docs/fy12osti/49153.pdf"> <span id="translatedtitle">innovati nNREL Confirms Large Potential for Grid Integration of <span class="hlt">Wind</span>, <span class="hlt">Solar</span> Power</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">innovati nNREL Confirms Large Potential for Grid Integration of <span class="hlt">Wind</span>, <span class="hlt">Solar</span> Power To fully harvest the nation's bountiful <span class="hlt">wind</span> and <span class="hlt">solar</span> resources, it is critical to know how much electrical power from penetrations of <span class="hlt">wind</span> power. NREL is a national laboratory of the U.S. Department of Energy, Office of Energy</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_16");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' 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src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">341</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/50961099"> <span id="translatedtitle">Application research of flywheel battery in the <span class="hlt">wind</span> and <span class="hlt">solar</span> complementary power generation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">As the <span class="hlt">wind</span> fluctuations, <span class="hlt">wind</span> and <span class="hlt">solar</span> power generation is unstable, and in the current, most of <span class="hlt">wind</span> and <span class="hlt">solar</span> power generations use battery energy storage technology. However, due to the chemical reaction speed limit, the battery can not be quickly charged, also can not be quickly discharged, even if the fast charge and discharge will also affect battery life,</p> <div class="credits"> <p class="dwt_author">Xianyi Qian</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">342</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.6967Y"> <span id="translatedtitle">Analysis of Properties of Small Transients in the <span class="hlt">Solar</span> <span class="hlt">Wind</span> 2007-2009: <span class="hlt">Wind</span> Observations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">During the <span class="hlt">solar</span> activity minimum 2007-2009 very few large transients (interplanetary coronal mass ejections, ICMEs) were observed. However, an interesting feature was the frequent occurrence of small transients (few hours' duration), as shown, for example over a two-month interval by Kilpua et al. (2009). In this work we present a comprehensive statistical analysis of small transients over the entire three-year period. Identification crieria are : (i) duration between 0.5 and 12 hours; (ii) low proton temperature; (iii) low proton beta; (iv) enhanced magnetic field strength; (v) diminished magnetic field variability; (vi) low Alfven Mach number; and (vii) higher-than-average over the three years of the electron-to-proton temperature ratio. In selecting events, we require small transients to satisfy criteria (i)-(iii) and, in addition, they should satisfy at least two of the other four signatures. We compare their properties with those of the <span class="hlt">solar</span> <span class="hlt">wind</span> during the same three-year period, and are thus able to isolate a number of features characterizing these small transients during this <span class="hlt">solar</span> activity minimum period. We search for small transients using observations acquired by the <span class="hlt">Wind</span> spacecraft. After removing those which are likely to be Alfvenic strctures, we find 131 examples, about 81 percent of which lie in the slow <span class="hlt">solar</span> <span class="hlt">wind</span> (< 450 km/s). We present six case studies to illustrate various interesting aspects of these configurations. We then give statistical results on the whole assembly. The average duration is about 4.3 hours, while 99 events (76 pervent) are shorter than 6 hours. The maximum magnetic field is about twice that of the average <span class="hlt">solar</span> <span class="hlt">wind</span> value, the proton beta is about four times smaller than ambient, and the Alfven Mach number is about one half of the average value.</p> <div class="credits"> <p class="dwt_author">Yu, Wenyaun; Farrugia, Charles; Galvin, Antoinette B.; Lugaz, Noe; Moestl, Christian; Kilpua, Emilia K. J.; Simunac, Kristin D. C.; Luhmann, Janet G.; Torbert, Roy B.; Szabo, Adam; Wilson, Lynn B., III; Oglivie, Keith W.; Lepping, Ronald P.; Sauvaud, Jean-Andre'</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">343</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008cosp...37..181B"> <span id="translatedtitle">Modeling of the <span class="hlt">solar</span> <span class="hlt">wind</span> with interstellar gas</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">As it is known the interface between the interplanetary plasma and the partially ionized gas of the local interstellar medium (LISM) is a region where there is a strong interaction between the <span class="hlt">solar</span> <span class="hlt">wind</span> (SW) and the LISM gas flow relative to the <span class="hlt">solar</span> system. A study of the structure and physical properties of this interface ("heliosheath" in literature) is at present especially actual due to Voyager-1 and Voyager-2 crossed the <span class="hlt">solar</span> <span class="hlt">wind</span> termination shock (TS) in December 2004 and September 2007, respectively, and entered to the inner heliosheath bounded by the heliopause. Gas dynamic and magneto-hydrodynamic (MHD) problems of the heliosheath structure are discussed in our presentation. In particular, the problems of the heliopause properties connected with the magnetic fields of the <span class="hlt">solar</span> and LISM origin are discussed. Effect of the LISM magnetic field on the outer heliosheath (a region between the bow shock and the heliopause) structure is considered. New theoretical problems, which must be solved to predict experimental results onboard Voyagers in the nearest time and in future possible projects, are formulated.</p> <div class="credits"> <p class="dwt_author">Baranov, Vladimir</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">344</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20000055757&hterms=Stem+sheets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DStem%2Bsheets"> <span id="translatedtitle">A New View of the Origin of the <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This paper uses white-light measurements made by the SOHO LASCO coronagraph and HAO Mauna Loa Mk III K-coronameter to illustrate the new view of <span class="hlt">solar</span> <span class="hlt">wind</span> structure deduced originally from radio occultation measurements. It is shown that the density profile closest to the Sun at 1.15 Ro, representing the imprint of the Sun, is carried essentially radially into interplanetary space by small-scale raylike structures that permeate the <span class="hlt">solar</span> corona and which have only been observed by radio occultation measurements. The only exception is the small volume of interplanetary space occupied by the heliospheric plasma sheet that evolves from coronal streamers within a few <span class="hlt">solar</span> radii of the Sun. The radial preservation of the density profile also implies that a significant fraction of field lines which extend into interplanetary space originate from the quiet Sun, and are indistinguishable in character from those emanating from polar coronal holes. The white-light measurements dispel the long-held belief that the boundaries of polar coronal holes diverge significantly, and further support the view originally proposed that the fast <span class="hlt">solar</span> <span class="hlt">wind</span> originates from the quiet Sun as well as polar coronal holes.</p> <div class="credits"> <p class="dwt_author">Woo, Richard; Habbal, Shadia Rifai</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">345</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ee.adfa.edu.au/staff/hrp/papers/bp12-c.pdf"> <span id="translatedtitle">Complementary Effect of <span class="hlt">Wind</span> and <span class="hlt">Solar</span> Energy Sources in a Microgrid</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Complementary Effect of <span class="hlt">Wind</span> and <span class="hlt">Solar</span> Energy Sources in a Microgrid M. A. Barik, Student Member. Index Terms--Microgrid, renewable energy sources, reactive power mismatch, <span class="hlt">solar</span> integration, voltage-mass energy, etc. Of them <span class="hlt">wind</span> and <span class="hlt">solar</span> energy is broadly used for their characteristics. This paper presents</p> <div class="credits"> <p class="dwt_author">Pota, Himanshu Roy</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">346</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/40745072"> <span id="translatedtitle">Particle propagation in the <span class="hlt">solar</span> <span class="hlt">wind</span>: Anomalous diffusion of magnetic field lines in turbulent magnetic fields</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In order to predict the entry of energetic particles of <span class="hlt">solar</span> origin into the Earth's magnetosphere, it is necessary to understand how these particles propagate in the <span class="hlt">solar</span> <span class="hlt">wind</span>. The random walk of magnetic field lines is studied numerically in the case that a spectrum of magnetic fluctuations is present. In particular, the anisotropic turbulence typical of the <span class="hlt">solar</span> <span class="hlt">wind</span></p> <div class="credits"> <p class="dwt_author">P. Veltri; G. Zimbardo; P. Pommois</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">347</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53635682"> <span id="translatedtitle">Plasma Magnet: Using a Rotating Magnetic Field to Couple Thrust From the <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Plasma Magnet concept aims to provide a large magnetic barrier to couple thrust from the <span class="hlt">solar</span> <span class="hlt">wind</span>. A spacecraft using Plasma Magnet propulsion would be able to move throughout the <span class="hlt">solar</span> system faster and more efficiently than possible using conventional chemical or electric propulsion. This dramatic improvement in performance is made possible by coupling thrust from the <span class="hlt">solar</span> <span class="hlt">wind</span>.</p> <div class="credits"> <p class="dwt_author">Louis Giersch; John Slough; Robert Winglee; Samuel Andreason</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">348</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.astropa.unipa.it/Library/OAPA_preprints/wave.ps.gz"> <span id="translatedtitle">Propagation of three--dimensional Alfv'en waves in a stratified, thermally conducting <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Propagation of three--dimensional Alfv'en waves in a stratified, thermally conducting <span class="hlt">solar</span> <span class="hlt">wind</span> S to the well--known thermal expansion of the <span class="hlt">solar</span> corona [Parker, 1958, 1963, 1991]. In particular Alfv'en waves in the <span class="hlt">solar</span> atmosphere and <span class="hlt">wind</span>, taking into account relevant physical effects</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">349</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22118811"> <span id="translatedtitle"><span class="hlt">SOLAR</span> <span class="hlt">WIND</span> STRAHL BROADENING BY SELF-GENERATED PLASMA WAVES</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet <span class="hlt">solar</span> conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the <span class="hlt">solar</span> <span class="hlt">wind</span> strahl during quiet <span class="hlt">solar</span> conditions.</p> <div class="credits"> <p class="dwt_author">Pavan, J.; Gaelzer, R. [UFPEL, Pelotas (Brazil); Vinas, A. F. [NASA GSFC, Greenbelt, MD 20771 (United States); Yoon, P. H. [IPST, UMD, College Park, MD (United States); Ziebell, L. F., E-mail: joel.pavan@ufpel.edu.br, E-mail: rudi@ufpel.edu.br, E-mail: adolfo.vinas@nasa.gov, E-mail: yoonp@umd.edu, E-mail: luiz.ziebell@ufrgs.br [UFRGS, Porto Alegre (Brazil)</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">350</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFMSH41A2173D"> <span id="translatedtitle">The Geomagnetic Response to Extreme <span class="hlt">Solar</span> <span class="hlt">Wind</span> Conditions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">It is well established that geomagnetic storms are related to interplanetary structures possessing southward interplanetary magnetic field component. Coronal mass ejection counterparts observed in the interplanetary medium, called ICMEs, are found to be one of the most frequent sources of such southward fields. ICME internal fields and sheath fields associated with their interplanetary shocks were found to be the dominant origins of Intense (Dst <100nT) and very intense (Dst<-200nT) geomagnetic storms in the ascending phase and maximum of the <span class="hlt">solar</span> cycle 23. Extreme events, in which Dst<-400nT, are less frequent, but they are all associated to ICMEs. Recent studies show that these events occur nearly once every 11 year <span class="hlt">solar</span> cycle. We investigate the geomagnetic response to these extreme <span class="hlt">solar</span> <span class="hlt">wind</span> conditions using observations and modeling.</p> <div class="credits"> <p class="dwt_author">Dal Lago, A.; Echer, E.; Balmaceda, L. A.; Rawat, R.; Vieira, L. A.; Gonzalez, W. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">351</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013ApJ...769L..30P"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">Wind</span> Strahl Broadening by Self-generated Plasma Waves</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet <span class="hlt">solar</span> conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the <span class="hlt">solar</span> <span class="hlt">wind</span> strahl during quiet <span class="hlt">solar</span> conditions.</p> <div class="credits"> <p class="dwt_author">Pavan, J.; Viñas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">352</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008PhDT........16H"> <span id="translatedtitle">Turbulence in inhomogeneous flows: Applications to the <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This work is devoted to the dynamics of fluids in a regime that can be described as being in a state of near incompressibility. The theory is derived under the assumption of low turbulent Mach number and is developed for flows where the usual incompressible description is not satisfactory and a full compressible treatment is too complex for analytical and sometimes computational studies. When the effects of compressibility are incorporated only weakly, a new description, referred to as "nearly incompressible hydrodynamics/magnetohydrodynamics" is obtained. The nearly incompressible theory developed by Zank and Matthaeus found excellent applicability to the <span class="hlt">solar</span> <span class="hlt">wind</span> flow, which typically possesses density fluctuations that are of the order of 10% from mean density values. However, the theory was derived only for homogeneous flows, and large-scale gradients in density, pressure, temperature and magnetic field are very common in the <span class="hlt">solar</span> <span class="hlt">wind</span>. So far it has been unclear how large-scale inhomogeneities would affect the usual incompressible and nearly incompressible descriptions. The work presented here addresses these deficiencies of nearly incompressible theory and generalizes it to include a large-scale inhomogeneous background which is time-stationary and spherically symmetric. The thesis is organized as follows. Chapter 1 introduces the <span class="hlt">solar</span> <span class="hlt">wind</span> concept and discusses the theoretical development of theories traditionally used to describe <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence. Chapter 2 elaborates the nearly incompressible theory of hydrodynamics in the presence of a large-scale inhomogeneous background and is based on the work of Hunana et al. 2006 (Phys. Rev. E 74, 026302). Chapter 3 presents two-dimensional direct numerical simulations of the lowest-order inhomogeneous system derived in Chapter 2 and focuses on the evolution of <span class="hlt">solar</span> <span class="hlt">wind</span> density fluctuations. Preliminary results were published by Hunana et al. 2007 (AIP Conf. Proc. 932, 45) and the most recent results by Hunana et al. 2008 (J. Geophys. Res., submitted). Chapter 4 generalizes the inhomogeneous nearly incompressible (NI) theory of hydrodynamics by considering heat conduction effects and Chapter 5 generalizes the inhomogeneous NI theory to magnetohydrodynamic flows. Appendix A discusses the details of our numerical technique and Appendix B derives an analytical form of the passive scalar spectrum for high Schmidt number turbulence in a useful form using modified Bessel function. This was published by Hunana and Zank 2008 (Phys. Rev. E 77, 017301).</p> <div class="credits"> <p class="dwt_author">Hunana, Peter</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">353</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52485674"> <span id="translatedtitle">Venus Express magnetic field observation of the <span class="hlt">solar</span> <span class="hlt">wind</span> interaction with Venus at <span class="hlt">solar</span> minimum</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The launch of Venus Express provides a new opportunity to study the <span class="hlt">solar</span> <span class="hlt">wind</span> interaction with Venus. Since Venus Express reused the spacecraft bus of Mars Express, which did not carry a magnetometer, no magnetic cleanliness program was implemented to minimize the spacecraft field and no boom was provided. Thus the data processing and cleaning tasks are formidable and unprecendented.</p> <div class="credits"> <p class="dwt_author">Tielong Zhang</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">354</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19980169246&hterms=primary+sources&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2528primary%2Bsources%2529"> <span id="translatedtitle">A Study of the Structure of the Source Region of the <span class="hlt">Solar</span> <span class="hlt">Wind</span> in Support of a <span class="hlt">Solar</span> Probe Mission</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Despite the richness of the information about the physical properties and the structure of the <span class="hlt">solar</span> <span class="hlt">wind</span> provided by the Ulysses and SOHO observations, fundamental questions regarding the nature of the coronal heating mechanisms, their source, and the manifestations of the fast and slow <span class="hlt">solar</span> <span class="hlt">wind</span>, still remain unanswered. The last unexplored frontier to establish the connection between the structure and dynamics of the <span class="hlt">solar</span> atmosphere, its extension into interplanetary space, and the mechanisms responsible for the evolution of the <span class="hlt">solar</span> <span class="hlt">wind</span>, is the corona between 1 and 30 R(sub s). A <span class="hlt">Solar</span> Probe mission offers an unprecedented opportunity to explore this frontier. The uniqueness of this mission stems from its trajectory in a plane perpendicular to the ecliptic which reaches within 9 R(sub s), of the <span class="hlt">solar</span> surface over the poles and 3 - 9 R(sub s), at the equator. With a complement of simultaneous in situ and remote sensing observations, this mission is destined to have a significant impact on our understanding of the fundamental processes that heat the corona and drive the <span class="hlt">solar</span> <span class="hlt">wind</span>. The <span class="hlt">Solar</span> Probe should be able to detect remnants and signatures of the processes which heat the corona and accelerate the <span class="hlt">solar</span> <span class="hlt">wind</span>. The primary objective of this proposal was to explore the structure of the different source regions of the <span class="hlt">solar</span> <span class="hlt">wind</span> through complementary observational and theoretical studies in support of a <span class="hlt">Solar</span> Probe mission.</p> <div class="credits"> <p class="dwt_author">Habbal , Shadia R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">355</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22020364"> <span id="translatedtitle">ON THE NATURE OF THE <span class="hlt">SOLAR</span> <span class="hlt">WIND</span> FROM CORONAL PSEUDOSTREAMERS</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Coronal pseudostreamers, which separate like-polarity coronal holes, do not have current sheet extensions, unlike the familiar helmet streamers that separate opposite-polarity holes. Both types of streamers taper into narrow plasma sheets that are maintained by continual interchange reconnection with the adjacent open magnetic field lines. White-light observations show that pseudostreamers do not emit plasma blobs; this important difference from helmet streamers is due to the convergence of like-polarity field lines above the X-point, which prevents the underlying loops from expanding outward and pinching off. The main component of the pseudostreamer <span class="hlt">wind</span> has the form of steady outflow along the open field lines rooted just inside the boundaries of the adjacent coronal holes. These flux tubes are characterized by very rapid expansion below the X-point, followed by reconvergence at greater heights. Analysis of an idealized pseudostreamer configuration shows that, as the separation between the underlying holes increases, the X-point rises and the expansion factor f{sub ss} at the source surface increases. In situ observations of pseudostreamer crossings indicate <span class="hlt">wind</span> speeds v ranging from {approx}350 to {approx}550 km s{sup -1}, with O{sup 7+}/O{sup 6+} ratios that are enhanced compared with those in high-speed streams but substantially lower than in the slow <span class="hlt">solar</span> <span class="hlt">wind</span>. Hydrodynamic energy-balance models show that the empirical v-f{sub ss} relation overestimates the <span class="hlt">wind</span> speeds from nonmonotonically expanding flux tubes, particularly when the X-point is located at low heights and f{sub ss} is small. We conclude that pseudostreamers produce a 'hybrid' type of outflow that is intermediate between classical slow and fast <span class="hlt">solar</span> <span class="hlt">wind</span>.</p> <div class="credits"> <p class="dwt_author">Wang, Y.-M.; Sheeley, N. R. J.R. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Grappin, R. [LUTH, Observatoire de Paris, CNRS, Universite Paris-Diderot, 92195 Meudon (France); Robbrecht, E., E-mail: yi.wang@nrl.navy.mil, E-mail: neil.sheeley@nrl.navy.mil, E-mail: roland.grappin@obspm.fr, E-mail: eva.robbrecht@oma.be [Royal Observatory of Belgium, 1180 Brussels (Belgium)</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-20</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">356</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006cosp...36.3041C"> <span id="translatedtitle">Tropical GW Acitivity Associated QBO Signal And Its <span class="hlt">Latitude</span> <span class="hlt">Dependence</span> Seen in A 7-year Long High Resolution Radiosonde Data-set</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A 7-year long high resolution radiosonde data-set for tropical latitude stations in the North Pacific was applied for investigating lower stratospheric inertial GW activity GW Investigation results for Truk Island 7 4N 151 8E indicated that the GW energy exhibited inter-annual variation that can be closely associated to those seen in the equitoral lower stratospheric zonal <span class="hlt">winds</span> i e the quasi-biennial oscillation QBO The GW energy always reached maximum at the time when the equatorial zonal <span class="hlt">winds</span> transit from Easterlies to Westlies This result is consistent with and further consolidated the previous result of Wang and Geller 2003 where only 4-year long data has been used The QBO like variation in GW activity disappeared at Gaum Island 13 5N 144 8E showing its <span class="hlt">latitude</span> <span class="hlt">dependence</span> which further reflected the latitudinal extent of the QBO Instead only seasonal variation was seen at this latitude Additionally for both latitude seasonal variation in the GW activity was clearly seen in the GW energy with the maximum happed in Northern winter January and minimum in Nothern summer June Details of the research will be introduced in the presentation</p> <div class="credits"> <p class="dwt_author">Chen, Z.; Lu, D.; Wang, X.-L.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">357</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/15306802"> <span id="translatedtitle">Transport of <span class="hlt">solar</span> <span class="hlt">wind</span> into Earth's magnetosphere through rolled-up Kelvin-Helmholtz vortices.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Establishing the mechanisms by which the <span class="hlt">solar</span> <span class="hlt">wind</span> enters Earth's magnetosphere is one of the biggest goals of magnetospheric physics, as it forms the basis of space weather phenomena such as magnetic storms and aurorae. It is generally believed that magnetic reconnection is the dominant process, especially during southward <span class="hlt">solar-wind</span> magnetic field conditions when the <span class="hlt">solar-wind</span> and geomagnetic fields are antiparallel at the low-latitude magnetopause. But the plasma content in the outer magnetosphere increases during northward <span class="hlt">solar-wind</span> magnetic field conditions, contrary to expectation if reconnection is dominant. Here we show that during northward <span class="hlt">solar-wind</span> magnetic field conditions-in the absence of active reconnection at low latitudes-there is a <span class="hlt">solar-wind</span> transport mechanism associated with the nonlinear phase of the Kelvin-Helmholtz instability. This can supply plasma sources for various space weather phenomena. PMID:15306802</p> <div class="credits"> <p class="dwt_author">Hasegawa, H; Fujimoto, M; Phan, T-D; Rème, H; Balogh, A; Dunlop, M W; Hashimoto, C; Tandokoro, R</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-08-12</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">358</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFMSM12A..01L"> <span id="translatedtitle">On the Mythical Relation Between <span class="hlt">Solar</span> <span class="hlt">Wind</span> Speed and Radiation Belt Electrons</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">It has been known for decades that the passage of high-speed <span class="hlt">solar</span> <span class="hlt">wind</span> correlates well with enhancements of radiation belt electrons in the magnetosphere. However an examination of fifteen years of continuous <span class="hlt">solar</span> <span class="hlt">wind</span> measurements and the daily averaged MeV electron fluxes at geosynchronous orbit shows that geomagnetic activity driven by a southward orientation of the interplanetary magnetic field, IMF, is a necessary condition for the MeV electron enhancement and that high-speed <span class="hlt">solar</span> <span class="hlt">wind</span> alone is neither necessary nor sufficient for the MeV electron enhancement. The reason that high-speed <span class="hlt">solar</span> <span class="hlt">wind</span> is almost always associated with the enhancement of MeV electrons is mainly because high-speed <span class="hlt">solar</span> <span class="hlt">wind</span> almost always has some southward components of the IMF. However, a combination of a long lasting high-speed <span class="hlt">solar</span> <span class="hlt">wind</span> and a southward oriented IMF produce highest fluxes of MeV electrons at geosynchronous orbit.</p> <div class="credits"> <p class="dwt_author">Li, X.; Temerin, M. A.; Baker, D. N.; Reeves, G. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">359</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19790060611&hterms=evolution+examples&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Devolution%2Bexamples"> <span id="translatedtitle">The radial evolution of the bulk properties of the <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Simultaneous <span class="hlt">solar-wind</span> proton data obtained at several heliocentric distances during radial alignments are compared. The radial variations associated with two high-speed streams in the <span class="hlt">solar</span> <span class="hlt">wind</span> are studied as examples of the radial evolution of the <span class="hlt">solar-wind</span> speed distribution and of high-speed streams in the <span class="hlt">solar</span> <span class="hlt">wind</span> as observed in the ecliptic plane in 1973. Pioneer 11 data on high-speed streams in the <span class="hlt">solar</span> <span class="hlt">wind</span> observed at about 1.5 and 3.7 AU are compared with the corresponding high-speed-stream data obtained at earth. These analyses indicate that as these high-speed streams propagated to these extended heliocentric distances, there was an erosion of the highest speeds and a general narrowing of the speed distribution. These observations are consistent with the exchange of momentum in the <span class="hlt">solar</span> <span class="hlt">wind</span> between high-speed streams and low-speed streams as they propagate outward from the sun.</p> <div class="credits"> <p class="dwt_author">Intriligator, D. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1978-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">360</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51841554"> <span id="translatedtitle">The Effect of the Neutral <span class="hlt">Solar</span> <span class="hlt">Wind</span> Component upon the Interaction of the <span class="hlt">Solar</span> System with the Interstellar Gas Stream</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The interaction between the neutral <span class="hlt">solar-wind</span> component and the ionized component of the interstellar gas may significantly influence the gas parameters. Proper allowance for this effect may alter our ideas about processes in the <span class="hlt">solar-wind</span> deceleration zone, and measurements of the L..cap alpha.. brightness of the interstellar gas may have to be interpreted.</p> <div class="credits"> <p class="dwt_author">M. A. Gruntman</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_17");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_18");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a style="font-weight: bold;">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_20");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">361</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/ja/v075/i016/JA075i016p03147/JA075i016p03147.pdf"> <span id="translatedtitle">The Equilibrium Anisotropy in the Flux of 10Mev <span class="hlt">Solar</span> Flare Particles and Their Convection in the <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The portion of an anisotropy, in the flux of cosmic rays in the interplaneta .ry medium, that arises from the motion of the <span class="hlt">solar</span> <span class="hlt">wind</span> plasma is in the same direction as the flow of the <span class="hlt">solar</span> <span class="hlt">wind</span> and is not perpendicular to the interplanetary magnetic field. The amplitude of this convective component of anisotropy is given by the Compton-Getting</p> <div class="credits"> <p class="dwt_author">Miriam A. Forman</p> <p class="dwt_publisher"></p> <p class="publishDate">1970-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">362</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/1087208"> <span id="translatedtitle">Using <span class="hlt">Solar</span> Business Models to Expand the Distributed <span class="hlt">Wind</span> Market (Presentation)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This presentation to attendees at <span class="hlt">Wind</span> Powering America's All-States Summit in Chicago describes business models that were responsible for rapid growth in the <span class="hlt">solar</span> industry and that may be applicable to the distributed <span class="hlt">wind</span> industry as well.</p> <div class="credits"> <p class="dwt_author">Savage, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">363</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19740010336&hterms=solar+particles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bparticles"> <span id="translatedtitle">Measurements of heavy <span class="hlt">solar</span> <span class="hlt">wind</span> and higher energy <span class="hlt">solar</span> particles during the Apollo 17 mission</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The lunar surface cosmic ray experiment, consisting of sets of mica, glass, plastic, and metal foil detectors, was successfully deployed on the Apollo 17 mission. One set of detectors was exposed directly to sunlight and another set was placed in shade. Preliminary scanning of the mica detectors shows the expected registration of heavy <span class="hlt">solar</span> <span class="hlt">wind</span> ions in the sample exposed directly to the sun. The initial results indicate a depletion of very-heavy <span class="hlt">solar</span> <span class="hlt">wind</span> ions. The effect is probably not real but is caused by scanning inefficiencies. Despite the lack of any pronounced <span class="hlt">solar</span> activity, energetic heavy particles with energies extending to 1 MeV/nucleon were observed. Equal track densities of approximately 6000 tracks/cm sq 0.5 microns in length were measured in mica samples exposed in both sunlight and shade.</p> <div class="credits"> <p class="dwt_author">Walker, R. M.; Zinner, E.; Maurette, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1973-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">364</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20090002604&hterms=phenomenological&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dphenomenological"> <span id="translatedtitle">Alfven Waves and Turbulence in the <span class="hlt">Solar</span> Atmosphere and <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We solve the problem of propagation and dissipation of Alfvenic turbulence in a model <span class="hlt">solar</span> atmosphere consisting of a static photosphere and chromosphere, transition region, and open corona and <span class="hlt">solar</span> <span class="hlt">wind</span> using a phenomenological model for the turbulent dissipation based on wave reflection. We show that most of the dissipation for a given wave frequency spectrum occurs in the lower corona, and the overall rms amplitude of the fluctuations evolves in a way consistent with observations. The frequency spectrum for a Kolmogorov-like slope is not found to change dramatically from the photosphere to the <span class="hlt">solar</span> <span class="hlt">wind</span>; however, it does preserve signatures of transmission throughout the lower atmospheric layers, namely, oscillations in the spectrum at high frequencies reminiscent of the resonances found in the linear case. These may disappear once more realistic couplings for the nonlinear terms are introduced or if time-dependent variability of the lower atmospheric layer is introduced.</p> <div class="credits"> <p class="dwt_author">Verdini, Andrea; Velli, Marco</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">365</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20040111086&hterms=pic+code&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpic%2Bcode"> <span id="translatedtitle">Simulations of <span class="hlt">Solar</span> <span class="hlt">Wind</span> Plasma Flow Around a Simple <span class="hlt">Solar</span> Sail</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">In recent years, a number of <span class="hlt">solar</span> sail missions of various designs and sizes have been proposed (e.g., Geostorm). Of importance to these missions is the interaction between the ambient <span class="hlt">solar</span> <span class="hlt">wind</span> plasma environment and the sail. Assuming a typical 1 AU <span class="hlt">solar</span> <span class="hlt">wind</span> environment of 400 km/s velocity, 3.5 cu cm density, ion temperature of approx.10 eV, electron temperature of 40 eV, and an ambient magnetic field strength of 10(exp -4) G, a first order estimate of the plasma interaction with square <span class="hlt">solar</span> sails on the order of the sizes being considered for a Geostorm mission (50 m x 50 m and 75 m x 75 m corresponding to approx.2 and approx.3 times the Debye length in the plasma) is carried out. First, a crude current balance for the sail surface immersed in the plasma environment and in sunlight was used to estimate the surface potential of the model sails. This gave surface potentials of approx.10 V positive relative to the <span class="hlt">solar</span> <span class="hlt">wind</span> plasma. A 3-D, Electrostatic Particle-in-Cell (PIC) code was then used to simulate the <span class="hlt">solar</span> <span class="hlt">wind</span> flowing around the <span class="hlt">solar</span> sail. It is assumed in the code that the <span class="hlt">solar</span> <span class="hlt">wind</span> protons can be treated as particles while the electrons follow a Boltzmann distribution. Next, the electric field and particle trajectories are solved self-consistently to give the proton flow field, the electrostatic field around the sail, and the plasma density in 3-D. The model sail was found to be surrounded by a plasma sheath within which the potential is positive compared to the ambient plasma and followed by a separate plasma wake which is negative relative to the plasma. This structure departs dramatically from a negatively charged plate such as might be found in the Earth s ionosphere on the night side where both the plate and its negative wake are contiguous. The implications of these findings are discussed as they apply to the proposed Geostorm <span class="hlt">solar</span> sail mission.</p> <div class="credits"> <p class="dwt_author">Garrett, Henry B.; Wang, Joseph</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">366</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://svs.gsfc.nasa.gov/vis/a000000/a000700/a000786/index.html"> <span id="translatedtitle">Polar Visible Aurora: Low <span class="hlt">Solar</span> <span class="hlt">Wind</span> Conditions on May 11, 1999 over the North Pole</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">On May 11, 1999, the <span class="hlt">solar</span> <span class="hlt">wind</span> that blows constantly from the Sun virtually disappeared. Dropping to a small fraction of its normal density and to half its normal speed, the <span class="hlt">solar</span> <span class="hlt">wind</span> died down enough to allow physicists to observe particles flowing directly from the Suns corona to Earth. This severe change in the <span class="hlt">solar</span> <span class="hlt">wind</span> also drastically changed the shape of Earths magnetic field and produced a rare auroral display at Earths North Pole.</p> <div class="credits"> <p class="dwt_author">Shirah, Greg; Chenette, David; Sigwarth, John; Carlowicz, Mike</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-12-08</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">367</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://svs.gsfc.nasa.gov/vis/a000000/a000700/a000785/index.html"> <span id="translatedtitle">Polar Visible Aurora: High <span class="hlt">Solar</span> <span class="hlt">Wind</span> Conditions on April 17, 1999 over the North Pole</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">On May 11, 1999, the <span class="hlt">solar</span> <span class="hlt">wind</span> that blows constantly from the Sun virtually disappeared. Dropping to a small fraction of its normal density and to half its normal speed, the <span class="hlt">solar</span> <span class="hlt">wind</span> died down enough to allow physicists to observe particles flowing directly from the Suns corona to Earth. This severe change in the <span class="hlt">solar</span> <span class="hlt">wind</span> also drastically changed the shape of Earths magnetic field and produced a rare auroral display at Earths North Pole.</p> <div class="credits"> <p class="dwt_author">Shirah, Greg; Chenette, David; Sigwarth, John; Carlowicz, Mike</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-12-08</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">368</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53280770"> <span id="translatedtitle">Utilization of <span class="hlt">wind\\/solar</span> energy in generating electricity in Saudi Arabia</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Solar</span> and <span class="hlt">wind</span> data averages gathered for five years and plans for a 1.2-1.4 kW <span class="hlt">solar</span> <span class="hlt">wind</span> energy plant at Riyadh, Saudi Arabia are presented. <span class="hlt">Wind</span> speeds were gathered at 2 m height averaging 3.9 m\\/sec, and extrapolated to 22 m and 5.45 m\\/sec; average <span class="hlt">solar</span> intensity was found to be 600 W\\/sq m between 6 a.m. and 6 p.m.</p> <div class="credits"> <p class="dwt_author">A. E. M. Nasser; A. E. M</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">369</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/48901806"> <span id="translatedtitle">On the momentum transfer of the <span class="hlt">solar</span> <span class="hlt">wind</span> to the Martian topside ionosphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Hot plasma measurements from the Soviet Phobos-2 spacecraft in the Martian magnetosphere suggests that the <span class="hlt">solar</span> <span class="hlt">wind</span> interaction with Mars is cometary-like, with mass loading of the <span class="hlt">solar</span> <span class="hlt">wind</span> and ion pick-up occurring also outside the subsolar bow-shock. The interaction is characterized by a pronounced decrease of the <span class="hlt">solar</span> <span class="hlt">wind</span> speed inside what has teen termed the mass-loading boundary (MLB).</p> <div class="credits"> <p class="dwt_author">R. Lundin; E. M. Dubinin; H. Koskinen; O. Norberg; N. Pissarenko; S. W. Barabash</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">370</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://svs.gsfc.nasa.gov/vis/a000000/a000700/a000788/index.html"> <span id="translatedtitle">Polar Visible Aurora: Normal <span class="hlt">Solar</span> <span class="hlt">Wind</span> Conditions on November 13, 1999 over the North Pole</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">On May 11, 1999, the <span class="hlt">solar</span> <span class="hlt">wind</span> that blows constantly from the Sun virtually disappeared. Dropping to a small fraction of its normal density and to half its normal speed, the <span class="hlt">solar</span> <span class="hlt">wind</span> died down enough to allow physicists to observe particles flowing directly from the Suns corona to Earth. This severe change in the <span class="hlt">solar</span> <span class="hlt">wind</span> also drastically changed the shape of Earths magnetic field and produced a rare auroral display at Earths North Pole.</p> <div class="credits"> <p class="dwt_author">Shirah, Greg; Chenette, David; Sigwarth, John; Carlowicz, Mike</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-12-08</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">371</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.4682H"> <span id="translatedtitle">The <span class="hlt">solar</span> <span class="hlt">wind</span> as a turbulence laboratory- some new quantitative points of contact between theory and <span class="hlt">solar</span> <span class="hlt">wind</span> observations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Single point observations of the high Reynolds number <span class="hlt">solar</span> <span class="hlt">wind</span> flow, suitable for the study of turbulence, are on timescales from below ion kinetic scales up to days, providing extensive datasets for the study of plasma turbulence. Central to the concept of using the <span class="hlt">solar</span> <span class="hlt">wind</span> as a test laboratory for plasma turbulence are methods that allow direct quantitative comparison between the predictions of theory and simulation, and the observations. Critically, theoretical predictions, and data analysis methods, must come together in a manner in which uncertainties can be well understood, and thus different theoretical scenarios be distinguished unambiguously. Scaling is a key prediction of theories of infinite range turbulence. Its full characterization requires the scaling exponents of all the moments of the probability density of fluctuations as a function of scale. In practice, only the first few moments are accessible. Comparisons with theory often focus on the second moment scaling, that is, the exponent of the power spectral density (PSD). We focus on what can be learned from two key properties of turbulent fluctuations: components of the tensor power spectral density, and the functional form and scaling of the non- Gaussian pdf of fluctuations. <span class="hlt">Solar</span> <span class="hlt">wind</span> plasma turbulence is anisotropic due to the presence of a background field, so that in general the power spectral density (or correlation) tensor is needed to characterise the turbulence. We focus on the ratios of the PSD tensor terms which are sensitive to the scaling exponent, providing a method for direct observational tests of theories. The reduced PSD tensor accessed by single spacecraft measurements yields ratios of perpendicular terms which we show are robust to uncertainties. In the MHD inertial range of turbulence in the <span class="hlt">solar</span> <span class="hlt">wind</span>, these can clearly distinguish turbulence theories as we discuss[1]. They also offer insights into the physics below the ion kinetic scales where a further scaling range suggests a kinetic range turbulence. Ideal fluid turbulence is characterized by non-Gaussian distributions of fluctuations which become progressively 'fat-tailed'; on smaller scales, and which exhibit a multifractal scale invariance, a behaviour also seen in the MHD inertial range of turbulence in the <span class="hlt">solar</span> <span class="hlt">wind</span>. We show that below the ion kinetic scales there is instead a cross-over to a quantitatively distinct global scale invariance[2] and discuss the implications for the physics of kinetic range turbulence. [1] A. J. Turner, G. Gogoberidze, S. C. Chapman, Nonaxisymmetric anisotropy of <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence as a direct test for models of magnetohydrodynamic turbulence, Phys. Rev. Lett., 108, 085001, (2012) [2] Kiyani, K. S. C. Chapman, F. Sahraoui, B. Hnat, O. Fauvarque, Yu. V. Khotyaintsev, Enhanced magnetic compressibility and isotropic scale-invariance at sub-ion Larmor scales in <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence, Ap. J., 763, 10, (2013)</p> <div class="credits"> <p class="dwt_author">Hnat, Bogdan; Chapman, Sandra; Gogoberidze, Giga; Kiyani, Khurom; Osman, Kareem; Turner, Andrew</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">372</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19960021353&hterms=ips&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dips"> <span id="translatedtitle">Critical point of the <span class="hlt">solar</span> <span class="hlt">wind</span> by radio sounding data</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Results of the close-to-Sun plasmas sounding at the transonic region of the <span class="hlt">solar</span> <span class="hlt">wind</span>, where the sub-to supersonic flow transition proceeds (at 10 to 40 <span class="hlt">solar</span> radii from the Sun), are presented. Natural sources of two types were used, water vapour maser sources at 1.35 cm and guasars at 2.9 m wavelength. scattering observations cover the period of 1986 to 1993, Russian Academy of Sciences telescopes RT-22 and DCR-1000 were used, IPS index and scattering angle being the immediate results of observations. Extensive studies of the scintillation index and scattering angle radial profiles reveal a remarkable structural detail, 'transonic region forrunner'-narrow region of diminished scattering close to the internal border of the extended transonic region with its characteristic enhanced scattering. Comparisons of the scattering and plasma velocity profiles let it possible to determine the critical point positions by the comparatively simple scattering observations. This new possibility widely improves the process of the basic data accumulation in the fundamental problem of the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration mechanism.</p> <div class="credits"> <p class="dwt_author">Lotova, N. A.; Oraevsky, V. N.; Pisarenko, Ya. V.; Vladimirskii, K. V.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">373</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010AIPC.1216..648Y"> <span id="translatedtitle">Large-scale <span class="hlt">solar</span> <span class="hlt">wind</span> structures: occurrence rate and geoeffectiveness</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Large-scale phenomena in the <span class="hlt">solar</span> <span class="hlt">wind</span> are important elements of heliospheric physics and space weather. On the basis of the OMNI database of interplanetary measurements we identified large-scale structures of <span class="hlt">solar</span> <span class="hlt">wind</span> (SW types) for all time intervals during 1976-2000. Our classification includes quasi-steady types: (1) Heliospheric current sheet (HCS), (2) Slow and (3) Fast SW streams, respectively, from closed and open magnetic field structures in the <span class="hlt">solar</span> corona, and disturbed types: (4) Corotating interaction regions (CIR-compressed regions between slow and fast SW streams), (5) SHEATH (compressed regions ahead of MC/EJECTA) and (6) Magnetic cloud (MC) and (7) EJECTA as well as (8) direct and (9) reverse interplanetary shocks (see catalog on site ftp://ftp.iki.rssi.ru/pub/omni/ and paper [1] ). We discuss several preliminary results obtained with our catalog (see more details in http://www.iki.rssi.ru./people/yyermol_inf.html) including effects on the Space Weather.</p> <div class="credits"> <p class="dwt_author">Yermolaev, Yuri I.; Nikolaeva, Nadezhda S.; Lodkina, Irina G.; Yermolaev, Mikhail Yu.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">374</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ApJ...783L..19Z"> <span id="translatedtitle">Twisted Magnetic Flux Tubes in the <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Magnetic flux tubes in the <span class="hlt">solar</span> <span class="hlt">wind</span> can be twisted as they are transported from the <span class="hlt">solar</span> surface, where the tubes are twisted due to photospheric motions. It is suggested that the twisted magnetic tubes can be detected as the variation of total (thermal+magnetic) pressure during their passage through the observing satellite. We show that the total pressure of several observed twisted tubes resembles the theoretically expected profile. The twist of the isolated magnetic tube may explain the observed abrupt changes of magnetic field direction at tube walls. We have also found some evidence that the flux tube walls can be associated with local heating of the plasma and elevated proton and electron temperatures. For the tubes aligned with the Parker spiral, the twist angle can be estimated from the change of magnetic field direction. Stability analysis of twisted tubes shows that the critical twist angle of the tube with a homogeneous twist is 70°, but the angle can further decrease due to the motion of the tube with respect to the <span class="hlt">solar</span> <span class="hlt">wind</span> stream. The tubes with a stronger twist are unstable to the kink instability, therefore they probably cannot reach 1 AU.</p> <div class="credits"> <p class="dwt_author">Zaqarashvili, Teimuraz V.; Vörös, Zoltán; Narita, Yasuhito; Bruno, Roberto</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">375</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMSH41E..06M"> <span id="translatedtitle">Remote Sensing of <span class="hlt">Solar</span> <span class="hlt">Wind</span> Velocity Applying IPS Technique using MEXART</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Radio waves coming from compact cosmic radio sources are scattered by electron density fluctuations in the <span class="hlt">solar</span> <span class="hlt">wind</span> plasma, producing a diffraction pattern at Earth which moves along with the <span class="hlt">solar</span> <span class="hlt">wind</span>. This phenomenon results into flux density fluctuations observed by a radio telescope and it is known as Interplanetary Scintillation (IPS). By employing IPS observations, it is possible to track <span class="hlt">solar</span> <span class="hlt">wind</span> velocities in the inner heliosphere. The Mexican Array Radio Telescope (MEXART) is an new instrument devoted to IPS observations at 140 MHz. We present preliminar estimates of <span class="hlt">solar</span> <span class="hlt">wind</span> velocities by using IPS observations of the MEXART.</p> <div class="credits"> <p class="dwt_author">Mejia-Ambriz, J. C.; Gonzalez-Esparza, A.; Romero Hernandez, E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">376</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/108204"> <span id="translatedtitle">Ulysses <span class="hlt">solar</span> <span class="hlt">wind</span> plasma observations from peak southerly latitude through perihelion and beyond</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We present Ulysses <span class="hlt">solar</span> <span class="hlt">wind</span> plasma data from the peak southerly latitude of {minus}80.2{degrees} through +64.9{degrees} latitude on June 7, 1995. Ulysses encountered fast <span class="hlt">wind</span> throughout this time except for a 43{degrees} band centered on the <span class="hlt">solar</span> equator. Median mass flux was nearly constant with latitude, while speed and density had positive and negative poleward gradients, respectively. <span class="hlt">Solar</span> <span class="hlt">wind</span> momentum flux was highest at high latitudes, suggesting a latitudinal asymmetry in the heliopause cross section. <span class="hlt">Solar</span> <span class="hlt">wind</span> energy flux density was also highest at high latitudes.</p> <div class="credits"> <p class="dwt_author">Phillips, J.L.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; McComas, D.J. [Los Alamos National Lab., NM (United States); Goldstein, B.E.; Neugebauer, M. [Jet Propulsion Lab., Pasadena, CA (United States); Hammond, C.M. [SRI International, Menlo Park, CA (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">377</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/15716946"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">wind</span> dynamic pressure and electric field as the main factors controlling Saturn's aurorae.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The interaction of the <span class="hlt">solar</span> <span class="hlt">wind</span> with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the <span class="hlt">solar</span> <span class="hlt">wind</span> and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, whereas Saturn's magnetosphere has generally been considered to have both internal and <span class="hlt">solar-wind</span>-driven processes. This hypothesis, however, is tentative because of limited simultaneous <span class="hlt">solar</span> <span class="hlt">wind</span> and magnetospheric measurements. Here we report <span class="hlt">solar</span> <span class="hlt">wind</span> measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging we find that, unlike Jupiter, Saturn's aurorae respond strongly to <span class="hlt">solar</span> <span class="hlt">wind</span> conditions. But in contrast to Earth, the main controlling factor appears to be <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the <span class="hlt">solar</span> <span class="hlt">wind</span>, but the <span class="hlt">solar</span> <span class="hlt">wind</span> conditions that drive it differ from those that drive the Earth's magnetosphere. PMID:15716946</p> <div class="credits"> <p class="dwt_author">Crary, F J; Clarke, J T; Dougherty, M K; Hanlon, P G; Hansen, K C; Steinberg, J T; Barraclough, B L; Coates, A J; Gérard, J-C; Grodent, D; Kurth, W S; Mitchell, D G; Rymer, A M; Young, D T</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-02-17</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">378</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21565416"> <span id="translatedtitle">NO EVIDENCE FOR HEATING OF THE <span class="hlt">SOLAR</span> <span class="hlt">WIND</span> AT STRONG CURRENT SHEETS</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">It has been conjectured that strong current sheets are the sites of proton heating in the <span class="hlt">solar</span> <span class="hlt">wind</span>. For the present study, a strong current sheet is defined by a >45{sup 0} rotation of the <span class="hlt">solar-wind</span> magnetic-field direction in 128 s. A total of 194,070 strong current sheets at 1 AU are analyzed in the 1998-2010 ACE <span class="hlt">solar-wind</span> data set. The proton temperature, proton specific entropy, and electron temperature at each current sheet are compared with the same quantities in the plasmas adjacent to the current sheet. Statistically, the plasma at the current sheets is not hotter or of higher entropy than the plasmas just outside the current sheets. This is taken as evidence that there is no significant localized heating of the <span class="hlt">solar-wind</span> protons or electrons at strong current sheets. Current sheets are, however, found to be more prevalent in hotter <span class="hlt">solar-wind</span> plasma. This is because more current sheets are counted in the fast <span class="hlt">solar</span> <span class="hlt">wind</span> than in the slow <span class="hlt">solar</span> <span class="hlt">wind</span>, and the fast <span class="hlt">solar</span> <span class="hlt">wind</span> is hotter than the slow <span class="hlt">solar</span> <span class="hlt">wind</span>.</p> <div class="credits"> <p class="dwt_author">Borovsky, Joseph E. [Los Alamos National Laboratory, Los Alamos, NM (United States); Denton, Michael H. [Department of Physics, Lancaster University, Lancaster (United Kingdom)</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">379</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.5410K"> <span id="translatedtitle">Geomagnetic Reconstruction in Gaps of <span class="hlt">Solar</span> <span class="hlt">Wind</span> Parameters by Singular Spectrum Analysis</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The main historical — i.e., pre-1994 — <span class="hlt">solar-wind</span> and interplanetary magnetic field (IMF) observations come from measurements taken on board of the IMP-8 spacecraft. While the spacecraft crossed the magnetosheath and magnetosphere, it was not immersed in the <span class="hlt">solar</span> <span class="hlt">wind</span> at all times, and so large continuous gaps exist in the collected data. Even after 1994 there have been many data gaps in the <span class="hlt">solar</span> <span class="hlt">wind</span> data, though they are not as frequent and are usually shorter. The behavior of Earth's magnetosphere is strongly influenced by the <span class="hlt">solar</span> <span class="hlt">wind</span>. Various geomagnetic indices — such as Kp, Dst or AE —are inferred from ground-measured, and hence time-lagged magnetic disturbances that are caused by the magnetosphere's interaction with the <span class="hlt">solar</span> <span class="hlt">wind</span> and the embedded IMF; these indices are inferred from the ground and are typically available continuously in time, even when <span class="hlt">solar-wind</span> data are not. Broadly speaking, these indices can be considered as a proxy for the overall time-lagged magnetospheric response to the <span class="hlt">solar</span> driver, i.e., to the <span class="hlt">solar</span> <span class="hlt">wind</span> and IMF. We will demonstrate how to reconstruct data in the gaps of the <span class="hlt">solar</span> driver by using smooth spatio-temporal modes of co-variability inferred by singular spectrum analysis (SSA) from time-lagged correlations in multivariate data consisting of gappy-driver (<span class="hlt">solar</span> <span class="hlt">wind</span> and IMF) and continuous-response records (various geomagnetic indices),— while discarding the noise. Application of the reconstructed data to radiation belts modeling will be presented.</p> <div class="credits"> <p class="dwt_author">Kondrashov, Dmitri; Shprits, Yuri; Kellerman, Adam; Ghil, Michael</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">380</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.62.115&rank=74"> <span id="translatedtitle">Soho Observations Of The North Polar <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">The north polar coronal hole and the <span class="hlt">wind</span> originating from it have been the target of a week--long observing campaign with UVCS. The observations with UVCS in the Lyff and O VI (1032 A and 1037 A) lines have covered the heliocentric distance from 1.5 R fi to 3.5 R fi . The corresponding inner corona has been observed, during part of the campaign, with CDS and SUMER in several chromospheric and coronal lines, including those observed with UVCS. Several EIT images and some EIT fast sequences, taken during the observing campaign, provide the overall scenario of the polar coronal hole at a high level of detail. Key words: fast <span class="hlt">solar</span> <span class="hlt">wind</span>; coronal holes; spectroscopy.</p> <div class="credits"> <p class="dwt_author">Peres Ciaravella Betta</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_18");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' 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showDiv("page_21");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">381</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMSH51B2242T"> <span id="translatedtitle">How do discontinuities affect our understanding of <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In-situ <span class="hlt">solar</span> <span class="hlt">wind</span> observations of the magnetic field show a continuum in the power spectral density (PSD). The broad temporal extent of the PSD power-law between scales of seconds to an hour is reminiscent of turbulence in neutral fluids, with a value close to -5/3. In-situ <span class="hlt">solar</span> <span class="hlt">wind</span> observations thus offer an excellent opportunity to study MHD turbulence, which is ubiquitous in astrophysics. However, there are also discontinuities present in the <span class="hlt">solar</span> <span class="hlt">wind</span> in addition to the turbulence. Discontinuities are seen in the observed magnetic field time-series as abrupt changes in the magnetic field direction and/or magnitude. Thus, a topical question is what effect these discontinuities have on the quantitative analysis and signatures of turbulence. There has been considerable interest in quantifying the power anisotropy of MHD turbulence. All such studies require the background field direction to be determined. Here, we will investigate how the presence of discontinuities impacts upon those methods which require the local background field to be determined at each scale. We propose a scale-dependent threshold to identify/remove discontinuities from the observed time-series. This approach of removing discontinuities is novel in that it does not impose a characteristic scale upon the time-series, which is crucial in quantitative studies of turbulence. We find that the removal of discontinuities from the observed time-series can significantly alter the statistical properties inferred from the data when analysed in the framework of turbulence. These statistical measures include the power anisotropy and associated PSD exponents. In particular we find no evidence for distinct power-law exponents when examining the power anisotropy. As a consistency check we have also constructed a surrogate time-series from the observations that is composed solely of discontinuities. The surrogate demonstrates the effective "noise floor" present for all scales greater than a few ion-cyclotron scales produced by discontinuities in the observational time-series.</p> <div class="credits"> <p class="dwt_author">Turner, A. J.; Chapman, S. C.; Gogoberidze, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">382</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013SSRv..178..101A"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">Wind</span> Turbulence and the Role of Ion Instabilities</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Solar</span> <span class="hlt">wind</span> is probably the best laboratory to study turbulence in astrophysical plasmas. In addition to the presence of magnetic field, the differences with neutral fluid isotropic turbulence are: (i) weakness of collisional dissipation and (ii) presence of several characteristic space and time scales. In this paper we discuss observational properties of <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence in a large range from the MHD to the electron scales. At MHD scales, within the inertial range, turbulence cascade of magnetic fluctuations develops mostly in the plane perpendicular to the mean field, with the Kolmogorov scaling for the perpendicular cascade and for the parallel one. <span class="hlt">Solar</span> <span class="hlt">wind</span> turbulence is compressible in nature: density fluctuations at MHD scales have the Kolmogorov spectrum. Velocity fluctuations do not follow magnetic field ones: their spectrum is a power-law with a -3/2 spectral index. Probability distribution functions of different plasma parameters are not Gaussian, indicating presence of intermittency. At the moment there is no global model taking into account all these observed properties of the inertial range. At ion scales, turbulent spectra have a break, compressibility increases and the density fluctuation spectrum has a local flattening. Around ion scales, magnetic spectra are variable and ion instabilities occur as a function of the local plasma parameters. Between ion and electron scales, a small scale turbulent cascade seems to be established. It is characterized by a well defined power-law spectrum in magnetic and density fluctuations with a spectral index close to -2.8. Approaching electron scales, the fluctuations are no more self-similar: an exponential cut-off is usually observed (for time intervals without quasi-parallel whistlers) indicating an onset of dissipation. The small scale inertial range between ion and electron scales and the electron dissipation range can be together described by , with ??8/3 and the dissipation scale ? d close to the electron Larmor radius ? d ? ? e . The nature of this small scale cascade and a possible dissipation mechanism are still under debate.</p> <div class="credits"> <p class="dwt_author">Alexandrova, O.; Chen, C. H. K.; Sorriso-Valvo, L.; Horbury, T. S.; Bale, S. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">383</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ApJ...795...69B"> <span id="translatedtitle">A Study of Density Modulation Index in the Inner Heliospheric <span class="hlt">Solar</span> <span class="hlt">Wind</span> during <span class="hlt">Solar</span> Cycle 23</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The ratio of the rms electron density fluctuations to the background density in the <span class="hlt">solar</span> <span class="hlt">wind</span> (density modulation index, epsilon N ? ?N/N) is of vital importance for understanding several problems in heliospheric physics related to <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence. In this paper, we have investigated the behavior of epsilon N in the inner heliosphere from 0.26 to 0.82 AU. The density fluctuations ?N have been deduced using extensive ground-based observations of interplanetary scintillation at 327 MHz, which probe spatial scales of a few hundred kilometers. The background densities (N) have been derived using near-Earth observations from the Advanced Composition Explorer. Our analysis reveals that 0.001 <~ epsilon N <~ 0.02 and does not vary appreciably with heliocentric distance. We also find that epsilon N declines by 8% from 1998 to 2008. We discuss the impact of these findings on problems ranging from our understanding of Forbush decreases to the behavior of the <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure over the recent peculiar <span class="hlt">solar</span> minimum at the end of cycle 23.</p> <div class="credits"> <p class="dwt_author">Bisoi, Susanta Kumar; Janardhan, P.; Ingale, M.; Subramanian, P.; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">384</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19750043156&hterms=power+spectrum+magnetic+field+fluctuations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dpower%2Bspectrum%2Bmagnetic%2Bfield%2Bfluctuations"> <span id="translatedtitle">Low-frequency fluctuations in the <span class="hlt">solar</span> <span class="hlt">wind</span>. I - Theory</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Several simple relationships between the power spectra of density and velocity fluctuations and the power spectrum of magnetic field fluctuations are derived within the context of plasma kinetic theory. The theory is restricted to the low-frequency regime (less than the proton cyclotron frequency) where hydromagnetic turbulence is expected to play the most important role. The affects of Alfven and magnetosonic waves upon the plasma fluctuations are discussed separately. The results are then applied to proton fluctuations in the <span class="hlt">solar</span> <span class="hlt">wind</span>, demonstrating a connection between plasma and field fluctuations.</p> <div class="credits"> <p class="dwt_author">Wu, C. S.; Huba, J. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">1975-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">385</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://svs.gsfc.nasa.gov/vis/a000000/a002800/a002861/index.html"> <span id="translatedtitle">Reconnection: <span class="hlt">Solar</span> <span class="hlt">Wind</span> Breaches the Earths Magnetic Shield</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The Far Ultraviolet camera abord the IMAGE spacecraft captured this view of a proton aurora (the bright spot near the center of the view) as well as the ring of the electron aurora. The protons for this aurora came from the incoming <span class="hlt">solar</span> <span class="hlt">wind</span>. The made it though the Earths magnetic shield in a magnetic reconnection event higher in the magnetosphere which was detected by the Cluster satellite. Note: A corner appears in the data in the beginning as the IMAGE spacecraft moves into a position where it can view the entire north polar region.</p> <div class="credits"> <p class="dwt_author">Bridgman, Tom; Frey, Harald; Phan, Tai</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-12-04</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">386</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cdsweb.cern.ch/record/1235081"> <span id="translatedtitle">Linear magnetosonic waves in <span class="hlt">solar</span> <span class="hlt">wind</span> flow tubes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Nakariakov et al. (1996) investigated the linear magnetosonic waves trapped within <span class="hlt">solar</span> <span class="hlt">wind</span> flow tubes, where they accounted for a slab having boundaries at $x = \\pm d$ and extended up to infinity in the $y$ and $z$ directions. Srivastava and Dwivedi (2006) claimed to extend that work by considering a two-dimensional slab. We find that the work of Srivastava and Dwivedi (2006) is not for a two-dimensional slab and has a number of discrepancies. Further, their results for body waves are not reliable.</p> <div class="credits"> <p class="dwt_author">Chandra, Suresh; Musrif, P G; Sharma, Monika</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">387</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006sf2a.conf..537G"> <span id="translatedtitle">Magnetic fluctuation spectrum in the inner <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Waves and turbulence are ubiquitous in the inner <span class="hlt">solar</span> <span class="hlt">wind</span>. Whereas Alfvén waves and Kolmogorov-type energy spectra are found at low frequencies, whistler waves and steeper magnetic fluctuation power law spectra are detected at frequencies higher than a fraction of hertz (at 1 AU). This multi-scale turbulence behavior may be investigated in the framework of 3D Hall MHD. In that context, I have developed a wave turbulence analysis which shows that the steepening of magnetic spectra may be attributed to dispersive nonlinear processes rather than pure dissipation as often stated.</p> <div class="credits"> <p class="dwt_author">Galtier, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">388</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014AdSpR..54.2017S"> <span id="translatedtitle">Coupling of earth's magnetosphere, <span class="hlt">solar</span> <span class="hlt">wind</span> and lunar plasma environment</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Moon does not have significant atmosphere and magnetic field. So it was considered like a passive absorber of incoming plasma. The latest observation revealed that the significant deflected proton fluxes exist over magnetic anomalies at lunar surface. Such deflection implies that the magnetic anomalies may act as magnetosphere-like obstacles (mini-magnetospheres), modifying the upstream plasma. The present paper is aimed to describe one possible deflection mechanism and its relations to <span class="hlt">solar</span> <span class="hlt">wind</span> conditions. It was obtained that for considered conditions the suggested mechanism gives too low density of deflected protons. However for the big anomaly it can give amount of deflected protons in accordance with the observations.</p> <div class="credits"> <p class="dwt_author">Sadovski, A.; Skalsky, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">389</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19950024161&hterms=refraction+reflection&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drefraction%252C%2Breflection"> <span id="translatedtitle">On reflection of Alfven waves in the <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We have revisited the problem of propagation of toroidal and linear Alfven waves formulated by Heinemann and Olbert (1980) to compare WKB and non-WKB waves and their effects on the <span class="hlt">solar</span> <span class="hlt">wind</span>. They considered two <span class="hlt">solar</span> <span class="hlt">wind</span> models and showed that reflection is important for Alfven waves with periods of the order of one day and longer, and that non-WKB Alfven waves are no more effective in accelerating the <span class="hlt">solar</span> <span class="hlt">wind</span> than WKB waves. There are several recently published papers which seem to indicate that Alfven waves with periods of the order of several minutes should be treated as non-WKB waves and that these non-WKB waves exert a stronger acceleration force than WKB waves. The purpose of this paper is to study the origin of these discrepancies by performing parametric studies of the behavior of the waves under a variety of different conditions. In addition, we want to investigate two problems that have not been addressed by Heinemann and Olbert, namely, calculate the efficiency of Alfven wave reflection by using the reflection coefficient and identify the region of strongest wave reflection in different <span class="hlt">wind</span> models. To achieve these goals, we investigated the influence of temperature, electron density distribution, <span class="hlt">wind</span> velocity and magnetic field strength on the waves. The obtained results clearly demonstrate that Alfven wave reflection is strongly model dependent and that the strongest reflection can be expected in models with the base temperatures higher than 10(exp 6) K and with the base densities lower than 7 x 10(exp 7) cm(exp -3). In these models as well as in the models with lower temperatures and higher densities, Alfven waves with periods as short as several minutes have negligible reflection so that they can be treated as WKB waves; however, for Alfven waves with periods of the order of one hour or longer reflection is significant, requiring a non-WKB treatment. We also show that non-WKB, linear Alfven waves are always less effective in accelerating the plasma than WKB Alfven waves. Finally, it is evident from our results that the region of strongest wave reflection is usually located at the base of the models, and hence that interpretation of wave reflection based solely on the reflection coefficient can be misleading.</p> <div class="credits"> <p class="dwt_author">Krogulec, M.; Musielak, Z. E.; Suess, S. T.; Moore, R. L.; Nerney, S. F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">390</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cdsweb.cern.ch/record/1753522"> <span id="translatedtitle">EMMI - Electric <span class="hlt">Solar</span> <span class="hlt">Wind</span> Sail Facilitated Manned Mars Initiative</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">The novel propellantless electric <span class="hlt">solar</span> <span class="hlt">wind</span> sail (E-sail) concept promises efficient low thrust transportation in the <span class="hlt">solar</span> system outside Earth's magnetosphere. Combined with asteroid mining to provide water and synthetic cryogenic rocket fuel in orbits of Earth and Mars, possibilities for affordable continuous manned presence on Mars open up. Orbital fuel and water eliminate the exponential nature of the rocket equation and also enable reusable bidirectional Earth-Mars vehicles for continuous manned presence on Mars. Water can also be used as radiation shielding of the manned compartment, thus reducing the launch mass further. In addition, the presence of fuel in Mars orbit provides the option for an all-propulsive landing, thus potentially eliminating issues of heavy heat shields and augmenting the capability of pinpoint landing. With this E-sail enabled scheme, the recurrent cost of continuous bidirectional traffic between Earth and Mars might ultimately approach the recurrent cost of running the Interna...</p> <div class="credits"> <p class="dwt_author">Janhunen, Pekka; Paton, Mark</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">391</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008PhDT.........9J"> <span id="translatedtitle">Radial evolution of large-scale <span class="hlt">solar</span> <span class="hlt">wind</span> structures</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Stream interaction regions (SIRs) and interplanetary coronal mass ejections (ICMEs) are two types of large-scale <span class="hlt">solar</span> <span class="hlt">wind</span> structures. Both can cause interplanetary shocks, generate energetic particles, and affect planetary magnetospheres and ionospheres. One key element of successful space weather forecasting is being able to predict how these two structures evolve radially from the Sun. To answer this question and eliminate the <span class="hlt">solar</span> cycle effect as much as possible, we first compile SIR and ICME event lists using long-term <span class="hlt">solar</span> <span class="hlt">wind</span> observations at three different heliocentric distances: 0.72 AU using Pioneer Venus Orbiter during 1979-1988; 1 AU using <span class="hlt">Wind</span> and Advanced Composition Explorer (ACE) during 1995-2006; 5.3 AU using Ulysses during three aphelion passes within ˜110° of <span class="hlt">solar</span> ecliptic plane in 1992, late 1997-1998, and late 2003-2005. By analyzing the parameters of each event, we have obtained the statistics and <span class="hlt">solar</span> cycle variations of properties of SIRs and ICMEs at each heliocentric distance, representing the space environment for Venus, Earth, and Jupiter, respectively covered in Chapters 3-5. Through the comparison of the statistics at the three distances, we have obtained the radial evolution of SIRs and ICMEs. The SIR shock rate increases from 3% at 0.72 AU to 26% at 1 AU to 92% at 5.3 AU, and forward shocks predominate near the ecliptic plane. The ICME shock rate remains at about 60% all the way out to 5.3 AU. The SIR width increases almost linearly with heliocentric distance, changing from 0.2 to 1.2 AU from Venus to Jupiter orbit. In contrast, the ICME width increases as a power-law function of heliocentric distance with a power index of 0.82 within 1 AU and its radial velocity slows down greatly to equal that of the surrounding <span class="hlt">solar</span> <span class="hlt">wind</span> between 1 and 5.3 AU. The ICME expansion speed decreases by half from 1 to 5.3 AU. In addition, a third of them have interacted and become hybrid events by 5.3 AU. Besides statistical work, we have studied some SIRs observed by multiple spacecraft, showing some merging of small SIRs into one big SIR from 1 to 5.3 AU. The CCMC/ENLIL model is run to reproduce these events. We find the arrival time of some SIRs in the model can differ 2-3 days from observed and some SIR features are missing in the model. The <span class="hlt">solar</span> magnetogram input and <span class="hlt">solar</span> model part are critical for ENLIL output and the whole model chain needs to be improved. Moreover, some superfast ICMEs observed by ACE, Ulysses, and Cassini, during Oct.-Nov. 2003 are also compared with the population of regular ICMEs in this dissertation. Even at a distance of 8.7 AU from the Sun, they can be many times larger and faster than regular ICMEs.</p> <div class="credits"> <p class="dwt_author">Jian, Lan</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">392</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cdsweb.cern.ch/record/1184927"> <span id="translatedtitle">Quantifying the Anisotropy and <span class="hlt">Solar</span> Cycle Dependence of "$1/f$" <span class="hlt">Solar</span> <span class="hlt">Wind</span> Fluctuations Observed by Ace</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">The power spectrum of the evolving <span class="hlt">solar</span> <span class="hlt">wind</span> shows evidence of a spectral break between an inertial range of turbulent fluctuations at higher frequencies and a "$1/f$" like region at lower frequencies. In the ecliptic plane at $\\sim 1$ AU, this break occurs approximately at timescales of a few hours, and is observed in the power spectra of components of velocity and magnetic field. The "$1/f$" energy range is of more direct coronal origin than the inertial range, and carries signatures of the complex magnetic field structure of the <span class="hlt">solar</span> corona, and of footpoint stirring in the <span class="hlt">solar</span> photosphere. To quantify the scaling properties we use generic statistical methods such as generalised structure functions and PDFs, focusing on <span class="hlt">solar</span> cycle dependence and on anisotropy with respect to the background magnetic field. We present structure function analysis of magnetic and velocity field fluctuations, using a novel technique to decompose the fluctuations into directions parallel and perpendicular to the mean local ...</p> <div class="credits"> <p class="dwt_author">Nicol, R M; Dendy, R O</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">393</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014AAS...22432351D"> <span id="translatedtitle"><span class="hlt">Solar</span> Polar Jets Driven by Magnetic Reconnection, Gravity, and <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Polar jets are dynamic, narrow, radially extended structures observed in <span class="hlt">solar</span> EUV emission near the limb. They originate within the open field of coronal holes in “anemone” regions, which are intrusions of opposite magnetic polarity. The key topological feature is a magnetic null point atop a dome-shaped fan surface of field lines. Applied stresses readily distort the null into a current patch, eventually inducing interchange reconnection between the closed and open fields inside and outside the fan surface (Antiochos 1996). Previously, we demonstrated that magnetic free energy stored on twisted closed field lines inside the fan surface is released explosively by the onset of fast reconnection across the current patch (Pariat et al. 2009, 2010). A dense jet comprised of a nonlinear, torsional Alfvén wave is ejected into the outer corona along the newly reconnected open field lines. Now we are extending those exploratory simulations by including the effects of <span class="hlt">solar</span> gravity, <span class="hlt">solar</span> <span class="hlt">wind</span>, and expanding spherical geometry. We find that the model remains robust in the resulting more complex setting, with explosive energy release and dense jet formation occurring in the low corona due to the onset of a kink-like instability, as found in the earlier Cartesian, gravity-free, static-atmosphere cases. The spherical-geometry jet including gravity and <span class="hlt">wind</span> propagates far more rapidly into the outer corona and inner heliosphere than a comparison jet simulation that excludes those effects. We report detailed analyses of our new results, compare them with previous work, and discuss the implications for understanding remote and in-situ observations of <span class="hlt">solar</span> polar jets.This work was supported by NASA’s LWS TR&T program.</p> <div class="credits"> <p class="dwt_author">DeVore, C. Richard; Karpen, Judith T.; Antiochos, Spiro K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">394</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20070011399&hterms=helium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dhelium"> <span id="translatedtitle"><span class="hlt">Solar</span> <span class="hlt">Wind</span> Helium Abundance as a Function of Speed and Heliographic Latitude: Variation through a <span class="hlt">Solar</span> Cycle</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We present a study of the variation of the relative abundance of helium to hydrogen in the <span class="hlt">solar</span> <span class="hlt">wind</span> as a function of <span class="hlt">solar</span> <span class="hlt">wind</span> speed and heliographic latitude over the previous <span class="hlt">solar</span> cycle. The average values of A(sub He), the ratio of helium to hydrogen number densities, are calculated in 25 speed intervals over 27-day Carrington rotations using Faraday Cup observations from the <span class="hlt">Wind</span> spacecraft between 1995 and 2005. The higher speed and time resolution of this study compared to an earlier work with the <span class="hlt">Wind</span> observations has led to the discovery of three new aspects of A(sub He), modulation during <span class="hlt">solar</span> minimum from mid-1995 to mid-1997. First, we find that for <span class="hlt">solar</span> <span class="hlt">wind</span> speeds between 350 and 415 km/s, A(sub He), varies with a clear six-month periodicity, with a minimum value at the heliographic equatorial plane and a typical gradient of 0.01 per degree in latitude. For the slow <span class="hlt">wind</span> this is a 30% effect. We suggest that the latitudinal gradient may be due to an additional dependence of coronal proton flux on coronal field strength or the stability of coronal loops. Second, once the gradient is subtracted, we find that A(sub He), is a remarkably linear function of <span class="hlt">solar</span> <span class="hlt">wind</span> speed. Finally, we identify a vanishing speed, at which A(sub He), is zero, is 259 km/s and note that this speed corresponds to the minimum <span class="hlt">solar</span> <span class="hlt">wind</span> speed observed at one AU. The vanishing speed may be related to previous theoretical work in which enhancements of coronal helium lead to stagnation of the escaping proton flux. During <span class="hlt">solar</span> maximum the A(sub He), dependences on speed and latitude disappear, and we interpret this as evidence of two source regions for slow <span class="hlt">solar</span> <span class="hlt">wind</span> in the ecliptic plane, one being the <span class="hlt">solar</span> minimum streamer belt and the other likely being active regions.</p> <div class="credits"> <p class="dwt_author">Kasper, J. C.; Stenens, M. L.; Stevens, M. L.; Lazarus, A. J.; Steinberg, J. T.; Ogilvie, Keith W.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">395</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3627923"> <span id="translatedtitle">Three-dimensional exploration of the <span class="hlt">solar</span> <span class="hlt">wind</span> using observations of interplanetary scintillation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">The <span class="hlt">solar</span> <span class="hlt">wind</span>, a supersonic plasma flow continuously emanating from the Sun, governs the space environment in a vast region extending to the boundary of the heliosphere (?100 AU). Precise understanding of the <span class="hlt">solar</span> <span class="hlt">wind</span> is of importance not only because it will satisfy scientific interest in an enigmatic astrophysical phenomenon, but because it has broad impacts on relevant fields. Interplanetary scintillation (IPS) of compact radio sources at meter to centimeter wavelengths serves as a useful ground-based method for investigating the <span class="hlt">solar</span> <span class="hlt">wind</span>. IPS measurements of the <span class="hlt">solar</span> <span class="hlt">wind</span> at a frequency of 327 MHz have been carried out regularly since the 1980s using the multi-station system of the <span class="hlt">Solar</span>-Terrestrial Environment Laboratory (STEL) of Nagoya University. This paper reviews new aspects of the <span class="hlt">solar</span> <span class="hlt">wind</span> revealed from our IPS observations. PMID:23391604</p> <div class="credits"> <p class="dwt_author">TOKUMARU, Munetoshi</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">396</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008AGUFMSH13B1528M"> <span id="translatedtitle">2006 LWS TR&T <span class="hlt">Solar</span> <span class="hlt">Wind</span> Focused Science Topic Team: Overview of Current Results</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present a summary of the research conducted by the members of the 2006 LWS TR&T <span class="hlt">Solar</span> <span class="hlt">Wind</span> Focused Science Topic (FST) Team on the physical processes that heat and accelerate the <span class="hlt">solar</span> <span class="hlt">wind</span>. The Team applied a combination of theoretical studies, numerical simulations, and observations for their investigation of the role of energy sources and kinetic mechanisms responsible for the heating and acceleration of the <span class="hlt">solar</span> <span class="hlt">wind</span>. In particular, the FST Team examined magnetic reconnection, waves, and turbulence as possible heating mechanisms. Plasma properties and their evolution over the <span class="hlt">solar</span> cycle, determined from the analysis of remote and in situ measurements of <span class="hlt">solar</span> <span class="hlt">wind</span> source regions and streams, are being used to constrain the models. The consistency of candidate theoretical models with existing observational data for the <span class="hlt">solar</span> <span class="hlt">wind</span> will be discussed.</p> <div class="credits"> <p class="dwt_author">Miralles, M. P.; LWS Tr&T Solar Wind Fst Team</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">397</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008ARep...52..576E"> <span id="translatedtitle">Origins and properties of the quasi-stationary slow <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Comparisons of the brightness distributions of the white corona observed at distances of several <span class="hlt">solar</span> radii with <span class="hlt">solar</span> <span class="hlt">wind</span> velocities derived from interplanetary-scintillation observations, as well as analyses of <span class="hlt">solar</span> <span class="hlt">wind</span> data obtained on spacecraft from December 1994 to June 1995, indicate that the fast <span class="hlt">solar</span> <span class="hlt">wind</span> can contain plasma with velocities V ? 300 450 km/s, approaching those typical for the slow <span class="hlt">solar</span> <span class="hlt">wind</span> that flows in the streamer belt and chains of streamers. At the same time, certain other parameters, first and foremost the plasma density N and ratio T/N 0.5 (where T is the temperature), indicate that these two flows differ considerably. The slow <span class="hlt">solar</span> <span class="hlt">wind</span> flowing in the streamer belt and chains displays high densities N > 10 ± 2 cm-3 and low T/N 0.5 < 1.7 × 104 K cm3/2 at the Earth’s orbit. The number of slow <span class="hlt">solar-wind</span> sources observed in chains can be comparable with the number observed in the belt. The fast <span class="hlt">solar</span> <span class="hlt">wind</span> flowing from coronal holes always displays low densities N? 8 cm-3 and high T/N 0.5 > 1.7 × 104 K cm3/2. These properties probably indicate different origins of the fast and slow <span class="hlt">solar</span> <span class="hlt">winds</span>.</p> <div class="credits"> <p class="dwt_author">Eselevich, M. V.; Eselevich, V. G.; Fujiki, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">398</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020006321&hterms=Quasar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DQuasar"> <span id="translatedtitle">Exploration of <span class="hlt">Solar</span> <span class="hlt">Wind</span> Acceleration Region Using Interplanetary Scintillation of Water Vapor Maser Source and Quasars</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Single-station observations of interplanetary scintillation UPS) at three microwave frequencies 2, 8, and 22GHz, were carried out between 1989 and 1998 using a large (34-micro farad) radio telescope at the Kashima Space Research Center of the Communications Research Laboratory. The aim of these observations was to explore the near-sun <span class="hlt">solar</span> <span class="hlt">wind</span>, which is the key region for the study of the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration mechanism. Strong quasars, 3C279 and 3C273B, were used for the Kashima IPS observations at 2 and 8GHz, and a water-vapor maser source, IRC20431, was used for the IPS observations at 22GHz. <span class="hlt">Solar</span> <span class="hlt">wind</span> speeds derived from Kashima IPS data suggest that the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration takes place at radial distances between 10 and 30 <span class="hlt">solar</span> radii (Rs) from the sun. The properties of the turbulence spectrum (e.g. anisotropy, spectral index, inner scale) inferred from the Kashima data were found to change systematically in the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration region. While the <span class="hlt">solar</span> <span class="hlt">wind</span> in the maximum phase appears to be dominated by the slow <span class="hlt">wind</span>, fast and rarefied <span class="hlt">winds</span> associated with the coronal holes were found to develop significantly at high latitudes as the <span class="hlt">solar</span> activity declined. Nevertheless, the Kashima data suggests that the location of the acceleration region is stable throughout the <span class="hlt">solar</span> cycle.</p> <div class="credits"> <p class="dwt_author">Tokumaru, Munetoshi; Yamauchi, Yohei; Kondo, Tetsuro</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">399</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020011026&hterms=Quasar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DQuasar"> <span id="translatedtitle">Exploration of <span class="hlt">Solar</span> <span class="hlt">Wind</span> Acceleration Region Using Interplanetary Scintillation of Water Vapor Maser Source and Quasars</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Single-station observations of interplanetary scintillation (IPS) at three microwave frequencies; 2 GHz, 8 GHz and 22 GHz have been carried out between 1989 and 1998 using a large (34 m farad) radio telescope at the Kashima Space Research Center of the Communications Research Laboratory. The aim of these observations is to explore the near-sun <span class="hlt">solar</span> <span class="hlt">wind</span>, which is the key region for the study of the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration mechanism. Strong quasars; 3C279 and 3C273B were used for Kashima IPS observations at 2 GHz and 8 GHz, and a water vapor maser source, IRC20431 was used for the IPS observations at 22 GHz. <span class="hlt">Solar</span> <span class="hlt">wind</span> velocities derived from Kashima IPS data suggest that the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration takes place at radial distances between 10 and 30 <span class="hlt">solar</span> radii (R(sub s)) from the sun. Properties of the turbulence spectrum (e.g. anisotropy, spectral index, inner scale) inferred from Kashima data are found to change systematically in the <span class="hlt">solar</span> <span class="hlt">wind</span> acceleration region. While the <span class="hlt">solar</span> <span class="hlt">wind</span> in the maximum phase appears to be dominated by the slow <span class="hlt">wind</span>, fast and rarefied <span class="hlt">winds</span> associated with coronal holes are found to develop significantly at high latitudes as the <span class="hlt">solar</span> activity declines. Nevertheless, Kashima data suggests that the location of the acceleration region is stable throughout the <span class="hlt">solar</span> cycle.</p> <div class="credits"> <p class="dwt_author">Tokumaru, Munetoshi; Yamauchi, Yohei; Kondo, Tetsuro</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">400</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUSMSH31B..05O"> <span id="translatedtitle">Observations and models of the slow <span class="hlt">solar</span> <span class="hlt">wind</span> in coronal streamers during <span class="hlt">solar</span> minimum</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A quiescent dipolar streamer belt often dominated the coronal streamer structures during past <span class="hlt">solar</span> minima. Past UV observations with SOHO/UVCS show that the intensity of heavy ion emission lines (such as O VI and Mg X) is dimmer at the cores than at the streamer edges. Three-fluid 2.5D models indicated that the observed emission variability is the signature of slow <span class="hlt">solar</span> <span class="hlt">wind</span> outflow regions, where Coulomb coupling between the electron, protons, and heavy ions leads to enhanced emission of heavy ions at the edges of streamers. Recently, Ofman et al (2011, 2012) have modeled in detail the three-fluid interactions and the emission in a quiescent streamer due to Ly ?, O 5+, and Mg 9+ ions at <span class="hlt">solar</span> minimum, and used the model results to synthesize the corresponding line emissions. They found that the model results are in good agreement with observations, provided that the heavy ions experience preferential heating compared to protons. Similar results were found to hold for He++ ions in quiescent streamers. Recently, the 2.5D three-fluid model was extended to full 3D, allowing modeling the ion abundance variations in tilted dipole streamer belt, and eventually in <span class="hlt">solar</span> maximum streamers. I will discuss the implication of heavy ion emission structure in streamers and the corresponding three-fluid models on the understanding of the slow <span class="hlt">solar</span> <span class="hlt">wind</span> sources.</p> <div class="credits"> <p class="dwt_author">Ofman, L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-05-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_19");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" 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showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_22");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">401</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850030802&hterms=SOLITONS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSOLITONS"> <span id="translatedtitle">Surface solitary waves and solitons. [in <span class="hlt">solar</span> atmosphere and <span class="hlt">solar</span> <span class="hlt">wind</span> magnetic structure</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The <span class="hlt">solar</span> atmosphere and <span class="hlt">solar</span> <span class="hlt">wind</span> are magnetically structured. The structuring can include tangential discontinuities, which can support surface waves. Such waves can be dispersive. This means that dispersion and nonlinearity can balance in such a way that solitary waves (or solitons) can result. This general point is illustrated by a two-dimensional nonlinear analysis which explicitly demonstrates the presence of long-wavelength solitary waves propagating on tangential discontinuities. If the waves are only weakly nonlinear, then they obey the Korteweg-de Vries equation and are true solitons.</p> <div class="credits"> <p class="dwt_author">Hollweg, J. V.; Roberts, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">402</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21448958"> <span id="translatedtitle">OBSERVATIONS OF ANISOTROPIC SCALING OF <span class="hlt">SOLAR</span> <span class="hlt">WIND</span> TURBULENCE</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Using high-speed <span class="hlt">solar</span> <span class="hlt">wind</span> data recorded by the Ulysses spacecraft, we investigate and estimate the anisotropic inertial range scaling of the interplanetary magnetic field. We apply the method of the magnetic structure function (MSF), S{sup n} ({tau}) = (|b(t + {tau}) - b(t)| {sup n}) {proportional_to} {tau}{sup {zeta}(n)}, to analyze the scaling of <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence over the range from 1 s to 10{sup 4} s. By sorting the fluctuations according to the direction of the local mean magnetic field, we obtain a second-order structure function in (r, {Theta}) coordinates that reveals the scale-dependent anisotropy of the power spectrum. The scale-dependent anisotropy of the MSF indicates that the fluctuation energy tends to cascade toward the direction perpendicular to the local field. The dependence of the MSF scaling index {zeta} on the direction of the local field is found to be similar to that reported in Horbury et al. and Podesta, with {zeta}{sub perpendicular} = 0.53 {+-} 0.18 and {zeta}{sub ||} = 1.00 {+-} 0.14. Furthermore, we estimate and find the scaling law between the perpendicular and parallel scales r {sub ||} {proportional_to} r {sup 0.614} {sub perpendicular}, which implies the elongation along the parallel direction as the turbulence eddy evolves toward the small lengthscales. These results are in agreement with the predictions of magnetohydrodynamic turbulence theory.</p> <div class="credits"> <p class="dwt_author">Luo, Q. Y.; Wu, D. J., E-mail: qyluo@pmo.ac.c [Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008 (China)</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">403</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cdsweb.cern.ch/record/1538013"> <span id="translatedtitle">Velocity-Space Proton Diffusion in the <span class="hlt">Solar</span> <span class="hlt">Wind</span> Turbulence</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">We study a velocity-space quasilinear diffusion of the <span class="hlt">solar</span> <span class="hlt">wind</span> protons driven by oblique Alfven turbulence at proton kinetic scales. Turbulent fluctuations at these scales possess properties of kinetic Alfven waves (KAWs) that are efficient in Cherenkov resonant interactions. The proton diffusion proceeds via Cherenkov kicks and forms a quasilinear plateau - nonthermal proton tail in the velocity distribution function (VDF). The tails extend in velocity space along the mean magnetic field from 1 to (1.5-3) VA, depending on the spectral break position, turbulence amplitude at the spectral break, and spectral slope after the break. The most favorable conditions for the tail generation occur in the regions where the proton thermal and Alfven velocities are about the same, VTp/VA = 1. The estimated formation times are within 1-2 h for typical tails at 1 AU, which is much shorter than the <span class="hlt">solar</span> <span class="hlt">wind</span> expansion time. Our results suggest that the nonthermal proton tails, observed in-situ at all heliocentric distan...</p> <div class="credits"> <p class="dwt_author">Voitenko, Yuriy</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">404</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003AIPC..679..562F"> <span id="translatedtitle">Solitary Waves Observed By Cluster In the <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Short dropouts of the magnetic field intensity have been frequently observed in the <span class="hlt">solar</span> <span class="hlt">wind</span> on interplanetary spacecraft. But so far it could not be established whether these are caused by kinetic instabilities or whether they can be described as solitary MHD waves. The multi-satellite observations of the Cluster-mission allow for the first time to measure proton and electron distributions with a sufficient temporal and spatial resolution to tackle this question. We use measurements by the FGM magnetometer, the CIS ion spectrometer, the PEACE electron instrument and the Whisper plasma wave instrument to investigate the role of protons, heavy ions and electrons for the stability of the structures. We also use the 4-satellite observations of the Cluster magnetic field instrument to determine the proper motion of these structures relative to the <span class="hlt">solar</span> <span class="hlt">wind</span>. The presence of foreshock waves close to the Earth bowshock strongly limits the event selection. In the current paper we discuss a 10 s linear wave without sufficient particle data resolution and a 4 min wave for which particle distributions are available. The larger wave shows that the stability of the structure might be caused by changes in the thermal electron distributions while proton and ? distributions are unaffected.</p> <div class="credits"> <p class="dwt_author">Fränz, M.; Horbury, T. S.; Génot, V.; Moullard, O.; Rème, H.; Dandouras, I.; Fazakerley, A. N.; Korth, A.; Frutos-Alfaro, F.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">405</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://arxiv.org/pdf/0710.0763v1"> <span id="translatedtitle">Small Scale Energy Cascade of the <span class="hlt">Solar</span> <span class="hlt">Wind</span> Turbulence</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Magnetic fluctuations in the <span class="hlt">solar</span> <span class="hlt">wind</span> are distributed according to Kolmogorov's power law $f^{-5/3}$ below the ion cyclotron frequency $f_{ci}$. Above this frequency, the observed steeper power law is usually interpreted in two different ways: a dissipative range of the <span class="hlt">solar</span> <span class="hlt">wind</span> turbulence or another turbulent cascade, the nature of which is still an open question. Using the Cluster magnetic data we show that after the spectral break the intermittency increases toward higher frequencies, indicating the presence of non-linear interactions inherent to a new inertial range and not to the dissipative range. At the same time the level of compressible fluctuations raises. We show that the energy transfer rate and intermittency are sensitive to the level of compressibility of the magnetic fluctuations within the small scale inertial range. We conjecture that the time needed to establish this inertial range is shorter than the eddy-turnover time, and is related to dispersive effects. A simple phenomenological model, based on the compressible Hall MHD, predicts the magnetic spectrum $\\sim k^{-7/3+2\\alpha}$, which depends on the degree of plasma compression $\\alpha$.</p> <div class="credits"> <p class="dwt_author">O. Alexandrova; V. Carbone; P. Veltri; L. Sorriso-Valvo</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-10-03</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">406</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20040191319&hterms=miki&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmiki"> <span id="translatedtitle">Kinematic Treatment of CME Evolution in the <span class="hlt">Solar</span> <span class="hlt">Wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We present a kinematic study of the evolution of coronal mass ejections (CMEs) in the <span class="hlt">solar</span> <span class="hlt">wind</span>. Specifically, we consider the effects of: (1) spherical expansion; and (2) uniform expansion due to pressure gradients between the Interplanetary CME (ICME) and the ambient <span class="hlt">solar</span> <span class="hlt">wind</span>. We compare these results with an MHD model, which allows us to isolate these effects from the combined kinematic and dynamical effects, which are included in MHD models. They also provide compelling evidence that the fundamental cross section of so-called "force-free" flux ropes (or magnetic clouds) is neither circular or elliptical, but rather a convex-outward, "pancake" shape. We apply a force-free fitting to the magnetic vectors from the MHD simulation to assess how the distortion of the flux rope affects the fitting. In spite of these limitations, force-free fittings, which are straightforward to apply, do provide an important description of a number of parameters, including the radial dimension, orientation and chirality of the ICME.</p> <div class="credits"> <p class="dwt_author">Riley, Pete; Crooker, N. U.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">407</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020033162&hterms=maxwell+theory&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmaxwell%2Btheory"> <span id="translatedtitle">Mirror Instability in the <span class="hlt">Solar</span> <span class="hlt">Wind</span>: The Theory Revisited</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">"Magnetic holes", localized depressions in the interplanetary magnetic field, have been identified in Ulysses data over a range of several AU and as far as 23 degrees south in latitude by Winterhalter et al., who concluded that these structures are most likely the remnants of structures caused by occasional mirror-mode instability in the <span class="hlt">solar</span> <span class="hlt">wind</span>. However, these authors, like a number of previous investigators, used the mirror stability criterion derived from the kinetic theory under very special assumptions. On the other hand, theoretical investigations using the fully self-consistent kinetic theory (Vlasov-Maxwell equations) have shown that the mirror stability criterion is more complicated when electrons and ions have different anisotropies, as is normally the case in the <span class="hlt">solar</span> <span class="hlt">wind</span>. Winterhalter et al used an instability criterion of the form R is greater than 1, where R is a function of the thermal anisotropy; the correct criterion (for bi-Maxwellian distributions) is R R is greater than 1 - x(exp 2), where x is a real quantity that depends on both the proton anisotropy and electron anisotropy. So nonzero x would modify the Winterhalter et al results in the direction of reinforcing their conclusions. We have revisited the instability criterion in its most general form, allowing for (a) non-Maxwellian velocity distributions, (b) multiple ion species, and (c) interparticle streaming. These results should give sound theoretical grounding for future observational studies related to the mirror instability, by Ulysses and other spacecraft.</p> <div class="credits"> <p class="dwt_author">Barnes, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">408</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.4424P"> <span id="translatedtitle">Nonlinear Interaction of the <span class="hlt">Solar</span> <span class="hlt">Wind</span> with Earth's Bow Shock</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The bow shock is the best-known collisionless shocks in nature. We have known from early on that the <span class="hlt">solar</span> <span class="hlt">wind</span> (SW) interaction with the bow shock produces gyrating and reflected particles. Some of these particles travel back into the upstream region, perturb the oncoming SW, and excite a host of nonlinear structures including hot flow anomalies, foreshock cavities and density holes. We have examined these nonlinear structures using data from 2003 when the four Cluster satellites were in a string-of-pearl configuration. We find that the nonlinear structures are evolving as they are convected with the <span class="hlt">solar</span> <span class="hlt">wind</span> toward Earth producing many shock-like features similar to those at the bow shock. Full 1D PIC simulation has reproduced many of the features, but the simulation requirements are different from observations. For example, the simulation shows that directly transmitted SW occurs only when the Mach number is small (sub-critical shocks). However, observations show that SW particles can penetrate the bow shock even in super-critical perpendicular shocks. This talk will discuss the new observations and simulation results with emphasis on understanding the SW dissipation mechanisms across the bow shock.</p> <div class="credits"> <p class="dwt_author">Parks, George; Yang, Zhongwei; Liu, Ying; Lee, Ensang; Lin, Naiguo; Fu, Suiyan; Cao, Jinbin; Canu, Patrick; Dandouras, Iannis; Reme, Henri; Goldstein, Melvyn</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">409</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMGP11A..01T"> <span id="translatedtitle">The oldest geodynamo and shielding from the <span class="hlt">solar</span> <span class="hlt">wind</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Understanding the onset, strength and nature of the oldest geomagnetic field is important because of the tremendous erosive potential of the <span class="hlt">solar</span> <span class="hlt">wind</span> streaming from the rapidly rotating young Sun. Efforts to obtain ancient field records, however, must confront a plethora of obstacles posed by the Phanerozoic geologic events that have affected Earth's oldest rocks. The single silicate crystal paleointensity approach (Tarduno, Cottrell, Smirnov, Rev. Geophys., 2006) aims to see through these younger geologic events to uncover the oldest geodynamo record. Here I review previous and new paleointensity results from times close to the Proterozoic/Archean boundary ( ˜2.5 billion years ago), extending to the Paleoarchean ( ˜3.47 billion years ago), with new estimates of <span class="hlt">solar</span> <span class="hlt">wind</span> strength and magnetopause stand-off distance. Together these estimates suggest modification of Earth's early atmosphere, including loss of water, especially during coronal mass ejections. If high power models for the evolution of the core and geodynamo are correct (Aubert, Johnson, Tarduno, Space Sci. Rev., 2009), the earliest Earth lacked a magnetic field; in this case, water loss due to atmospheric erosion would have been extreme in the Hadean. Our ongoing efforts to investigate the Hadean record of the geodynamo through studies of the Jack Hills conglomerate of Western Australia, which hosts zircons up to 4.4 billion-years-old, will be discussed.</p> <div class="credits"> <p class="dwt_author">Tarduno, J. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">410</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20120016041&hterms=end+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dend%2Bearth"> <span id="translatedtitle">Near-Earth <span class="hlt">Solar</span> <span class="hlt">Wind</span> Flows and Related Geomagnetic Activity During more than Four <span class="hlt">Solar</span> Cycles (1963-2011)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">In past studies, we classified the near-Earth <span class="hlt">solar</span> <span class="hlt">wind</span> into three basic flow types based on inspection of <span class="hlt">solar</span> <span class="hlt">wind</span> plasma and magnetic field parameters in the OMNI database and additional data (e.g., geomagnetic indices, energetic particle, and cosmic ray observations). These flow types are: (1) High-speed streams associated with coronal holes at the Sun, (2) Slow, interstream <span class="hlt">solar</span> <span class="hlt">wind</span>, and (3) Transient flows originating with coronal mass ejections at the Sun, including interplanetary coronal mass ejections and the associated upstream shocks and post-shock regions. The <span class="hlt">solar</span> <span class="hlt">wind</span> classification in these previous studies commenced with observations in 1972. In the present study, as well as updating this classification to the end of 2011, we have extended the classification back to 1963, the beginning of near-Earth <span class="hlt">solar</span> <span class="hlt">wind</span> observations, thereby encompassing the complete <span class="hlt">solar</span> cycles 20 to 23 and the ascending phase of cycle 24. We discuss the cycle-to-cycle variations in near-Earth <span class="hlt">solar</span> <span class="hlt">wind</span> structures and l1e related geomagnetic activity over more than four <span class="hlt">solar</span> cycles, updating some of the results of our earlier studies.</p> <div class="credits"> <p class="dwt_author">Richardson, Ian G.; Cane, Hilary V.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">411</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007PhDT.........5B"> <span id="translatedtitle">Cometary X-rays. <span class="hlt">Solar</span> <span class="hlt">wind</span> charge exchange in cometary atmospheres</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The interaction of the <span class="hlt">solar</span> <span class="hlt">wind</span> with the planets and the interstellar medium is of key importance for the evolution of our <span class="hlt">solar</span> system. The interaction with Earth's atmosphere is best known for the northern light. In case of Mars, the interaction with the <span class="hlt">solar</span> <span class="hlt">wind</span> might have lead to the erosion of its atmosphere. <span class="hlt">Solar</span> <span class="hlt">wind</span>-atmosphere interactions can be studied particularly well in cometary atmospheres, because in that case the <span class="hlt">solar</span> <span class="hlt">wind</span> flow is not attenuated by a planetary magnetic field and interacts directly with its atmosphere, the coma. The size of the cometary atmosphere (in the order of 10(4-10^5) km) allows remote tracking of the ions as they penetrate into the comet's atmosphere, offering a unique window on the cometary atmosphere, the <span class="hlt">solar</span> <span class="hlt">wind</span> and the interaction of these two plasmas. When <span class="hlt">solar</span> <span class="hlt">wind</span> ions fly through an atmosphere they are neutralized via charge exchange reactions with the neutral gaseous species. These reactions depend strongly on target species and collision velocity. The resulting X-ray and Far-UV emission can therefore be regarded as a fingerprint of the underlying reaction, with many diagnostic qualities. My thesis studies have focussed on all aspects relevant for X-ray emission from comets: experimental studies of state-to-state charge exchange cross sections, observations of X-ray emission from comets with Chandra, XMM, and Swift, and theoretical modelling of the interaction of <span class="hlt">solar</span> <span class="hlt">wind</span> ions with cometary gasses and the resulting X-ray emission spectrum. Together, this has greatly improved our understanding of the interaction of the <span class="hlt">solar</span> <span class="hlt">wind</span> with <span class="hlt">solar</span> system objects and in more general, of physical processes in <span class="hlt">wind</span>-environment collisions. The thorough understanding of cometary charge exchange emission has opened the door to the direct observation of more complex <span class="hlt">solar</span> <span class="hlt">wind</span> interactions such as those with Mars and Venus.</p> <div class="credits"> <p class="dwt_author">Bodewits, Dennis</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">412</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://sprg.ssl.berkeley.edu/adminstuff/webpubs/2002_grl_1648.pdf"> <span id="translatedtitle">Proton aurora dynamics in response to the IMF and <span class="hlt">solar</span> <span class="hlt">wind</span> variations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Proton aurora dynamics in response to the IMF and <span class="hlt">solar</span> <span class="hlt">wind</span> variations S.-W. Chang,1,2 S. B. Mende; accepted 24 April 2002; published 13 July 2002. [1] On May 23, 2000, proton auroras observed by IMAGE FUV <span class="hlt">wind</span> parameters. A proton aurora brightened at high latitude poleward from the dayside oval after <span class="hlt">solar</span></p> <div class="credits"> <p class="dwt_author">California at Berkeley, University of</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">413</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://web.ift.uib.no/Romfysikk/RESEARCH/PAPERS/laundal08.pdf"> <span id="translatedtitle">Persistent global proton aurora caused by high <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Persistent global proton aurora caused by high <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure K. M. Laundal1 and N] Global images of the proton aurora taken with the SI-12 camera onboard the IMAGE satellite reveal a very direct relationship between the <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure and the intensity of the global proton aurora</p> <div class="credits"> <p class="dwt_author">Bergen, Universitetet i</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">414</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://sprg.ssl.berkeley.edu/adminstuff/webpubs/2003_jgr_8001.pdf"> <span id="translatedtitle">Sudden <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure enhancements and dayside detached auroras: IMAGE and DMSP observations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/epsearch/">E-print Network</a></p> <p class="result-summary">Sudden <span class="hlt">solar</span> <span class="hlt">wind</span> dynamic pressure enhancements and dayside detached auroras: IMAGE and DMSP 24 December 2002. [1] Dayside detached auroras (DDA) refer to auroras observed separate from/particle interactions; KEYWORDS: aurora, dayside detached aurora, proton precipitation, <span class="hlt">solar</span> <span class="hlt">wind</span> pressure enhancement</p> <div class="credits"> <p class="dwt_author">California at Berkeley, University of</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">415</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53034083"> <span id="translatedtitle">Power Anisotropy in the Magnetic Field Power Spectral Tensor of <span class="hlt">Solar</span> <span class="hlt">Wind</span> Turbulence</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We observe the anisotropy of the power spectral tensor of magnetic field fluctuations in the fast <span class="hlt">solar</span> <span class="hlt">wind</span> for the first time. In heliocentric RTN coordinates the power in each element of the tensor has a unique dependence on the angle between the magnetic field and velocity of the <span class="hlt">solar</span> <span class="hlt">wind</span> (\\\\theta) and the angle of the vector in the</p> <div class="credits"> <p class="dwt_author">Robert T. Wicks; Miriam A. Forman; Timothy S. Horbury; Sean Oughton</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">416</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/ja/v084/iA02/JA084iA02p00527/JA084iA02p00527.pdf"> <span id="translatedtitle">IMF orientation, <span class="hlt">solar</span> <span class="hlt">wind</span> velocity, and Pc 3--4 signals: A joint distribution</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Separate studies using the same micropulsation data base in the period range 10--150 s have shown earlier that signal levels recorded during September, October, and November 1969 at Calgary correlated positively with both <span class="hlt">solar</span> <span class="hlt">wind</span> alignment of the IMF and <span class="hlt">solar</span> <span class="hlt">wind</span> speed, but each correlation contained enough scatter to allow for influence of the other factor. In this report,</p> <div class="credits"> <p class="dwt_author">Eugene W. Greenstadt; Howard J. Singer; Christopher T. Russell; John V. Olson</p> <p class="dwt_publisher"></p> <p class="publishDate">1979-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">417</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/ja/v075/i001/JA075i001p00017/JA075i001p00017.pdf"> <span id="translatedtitle">INSTABILITIES ASSOCIATED WITH HEAT CONDUCTION IN THE <span class="hlt">SOLAR</span> <span class="hlt">WIND</span> AND THEIR CONSEQUENCES</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Associated with the large heat conduction in the <span class="hlt">solar</span> <span class="hlt">wind</span> is a skewing of the ion and electron distribution functions. It is shown that this collisional skewing of the electron distribution function can linearly excite collisionless ion-acoustic, electrostatic ion cyclotron, magnetoacoustic, and ion cyclotron wa