observed solar wind: Topics by Science.gov

Forecast of solar wind parameters according to STOP magnetograph observations

NASA Astrophysics Data System (ADS)

Tlatov, A. G.; Pashchenko, M. P.; Ponyavin, D. I.; Svidskii, P. M.; Peshcherov, V. S.; Demidov, M. L.

2016-12-01

The paper discusses the results of the forecast of solar wind parameters at a distance of 1 AU made according to observations made by the STOP telescope magnetograph during 2014-2015. The Wang-Sheeley-Arge (WSA) empirical model is used to reconstruct the magnetic field topology in the solar corona and estimate the solar wind speed in the interplanetary medium. The proposed model is adapted to STOP magnetograph observations. The results of the calculation of solar wind parameters are compared with ACE satellite measurements. It is shown that the use of STOP observations provides a significant correlation of predicted solar wind speed values with the observed ones.
XMM-Newton Observations of Solar Wind Charge Exchange Emission

NASA Technical Reports Server (NTRS)

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

2004-01-01

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

NASA Astrophysics Data System (ADS)

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

2017-06-01

A statistical investigation of 5 years of observations from the two-probe Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) mission reveals that strong compressional interactions occur infrequently at high altitudes near the ecliptic but can form in a wide range of solar wind conditions and can occur up to two lunar radii downstream from the lunar limb. The compressional events, some of which may represent small-scale collisionless shocks ("limb shocks"), occur in both steady and variable interplanetary magnetic field (IMF) conditions, with those forming in steady IMF well organized by the location of lunar remanent crustal magnetization. The events observed by ARTEMIS have similarities to ion foreshock phenomena, and those observed in variable IMF conditions may result from either local lunar interactions or distant terrestrial foreshock interactions. Observed velocity deflections associated with compressional events are always outward from the lunar wake, regardless of location and solar wind conditions. However, events for which the observed velocity deflection is parallel to the upstream motional electric field form in distinctly different solar wind conditions and locations than events with antiparallel deflections. Consideration of the momentum transfer between incoming and reflected solar wind populations helps explain the observed characteristics of the different groups of events.Plain Language SummaryWe survey the environment around the Moon to determine when and where strong amplifications in the charged particle density and magnetic field strength occur. These structures may be some of the smallest shock waves in the solar system, and learning about their formation informs us about the interaction of charged particles with small-scale magnetic fields throughout the solar system and beyond. We find that these compressions occur in an extended region </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22519953-new-horizons-solar-wind-around-pluto-swap-observations-solar-wind-from-au','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22519953-new-horizons-solar-wind-around-pluto-swap-observations-solar-wind-from-au">THE NEW HORIZONS SOLAR WIND AROUND PLUTO (SWAP) OBSERVATIONS OF THE SOLAR WIND FROM 11–33 au</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Elliott, H. A.; McComas, D. J.; Valek, P. The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parametersmore » and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T–V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T–V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730002079','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730002079">Spacecraft observations of the solar wind composition</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bame, S. J. 1972-01-01 Solar wind composition studies by means of plasma analyzers carried on various spacecraft are reviewed. The average ratio of helium to hydrogen over the solar cycle is close to 0.045; values as low as 0.0025 and as high as 0.25 have been observed. High values have been observed following solar flares and interplanetary shock waves when the flare gas driving the shock arrives at the spacecraft. Ions of He-3(+2), O-16(+6), and O-16(+7) have been observed with Vela 3 electrostatic analyzers. Further measurements with Vela 5 analyzers have shown the presence of N-14(+6), Si-28(+7) to Si-28(+9) and Fe-56(+7) to Fe-56(+12) ions. The relative abundance of oxygen, silicon, and iron in the solar wind of July 6, 1969, was 1.00, 0.21, and 0.17, which is very similar to reported values for the corona. The ratio of helium to oxygen is variable; the average value of He/O is close to 100, but values between 30 and 400 have been observed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840005044','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840005044">Iron charge states observed in the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ipavich, F. M.; Galvin, A. B.; Gloeckler, G.; Hovestadt, D.; Klecker, B.; Scholer, M. 1983-01-01 Solar wind measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE-3 are reported. The low energy section of approx the ULECA sensor selects particles by their energy per charge (over the range 3.6 keV/Q to 30 keV/Q) and simultaneously measures their total energy with two low-noise solid state detectors. Solar wind Fe charge state measurements from three time periods of high speed solar wind occurring during a post-shock flow and a coronal hole-associated high speed stream are presented. Analysis of the post-shock flow solar wind indicates the charge state distributions for Fe were peaked at approx +16, indicative of an unusually high coronal temperature (3,000,000 K). In contrast, the Fe charge state distribution observed in a coronal hole-associated high speed stream peaks at approx -9, indicating a much lower coronal temperature (1,400,000 K). This constitutes the first reported measurements of iron charge states in a coronal hole-associated high speed stream. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22356468-solar-wind-neon-abundance-observed-ace-swics-ulysses-swics','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22356468-solar-wind-neon-abundance-observed-ace-swics-ulysses-swics">The solar wind neon abundance observed with ACE/SWICS and ULYSSES/SWICS</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Shearer, Paul; Raines, Jim M.; Lepri, Susan T. Using in situ ion spectrometry data from ACE/SWICS, we determine the solar wind Ne/O elemental abundance ratio and examine its dependence on wind speed and evolution with the solar cycle. We find that Ne/O is inversely correlated with wind speed, is nearly constant in the fast wind, and correlates strongly with solar activity in the slow wind. In fast wind streams with speeds above 600 km s{sup –1}, we find Ne/O = 0.10 ± 0.02, in good agreement with the extensive polar observations by Ulysses/SWICS. In slow wind streams with speeds below 400 km s{sup –1}, Ne/O ranges from amore » low of 0.12 ± 0.02 at solar maximum to a high of 0.17 ± 0.03 at solar minimum. These measurements place new and significant empirical constraints on the fractionation mechanisms governing solar wind composition and have implications for the coronal and photospheric abundances of neon and oxygen. The results are made possible by a new data analysis method that robustly identifies rare elements in the measured ion spectra. The method is also applied to Ulysses/SWICS data, which confirms the ACE observations and extends our view of solar wind neon into the three-dimensional heliosphere.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020069138&hterms=firenze&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfirenze','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020069138&hterms=firenze&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfirenze">Solar Wind Characteristics from SOHO-Sun-Ulysses Quadrature Observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Poletto, Giannina; Suess, Steve T.; Six, N. Frank (Technical Monitor) 2002-01-01 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSH33A4129L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSH33A4129L">Solar Corona/Wind Composition and Origins of the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lepri, S. T.; Gilbert, J. A.; Landi, E.; Shearer, P.; von Steiger, R.; Zurbuchen, T. 2014-12-01 Measurements from ACE and Ulysses have revealed a multifaceted solar wind, with distinctly different kinetic and compositional properties dependent on the source region of the wind. One of the major outstanding issues in heliophysics concerns the origin and also predictability of quasi-stationary slow solar wind. While the fast solar wind is now proven to originate within large polar coronal holes, the source of the slow solar wind remains particularly elusive and has been the subject of long debate, leading to models that are stationary and also reconnection based - such as interchange or so-called S-web based models. Our talk will focus on observational constraints of solar wind sources and their evolution during the solar cycle. In particular, we will point out long-term variations of wind composition and dynamic properties, particularly focused on the abundance of elements with low First Ionization Potential (FIP), which have been routinely measured on both ACE and Ulysses spacecraft. We will use these in situ observations, and remote sensing data where available, to provide constraints for solar wind origin during the solar cycle, and on their correspondence to predictions for models of the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23383910','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23383910">Ion kinetic scale in the solar wind observed.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Śafránková, Jana; Němeček, Zdeněk; Přech, Lubomír; Zastenker, Georgy N 2013-01-11 This Letter shows the first results from the solar wind monitor onboard the Spektr-R spacecraft which measures plasma moments with a time resolution of 31 ms. This high-time resolution allows us to make direct observations of solar wind turbulence below ion kinetic length scales. We present examples of the frequency spectra of the density, velocity, and thermal velocity. Our study reveals that although these parameters exhibit the same behavior at the magnetohydrodynamic scale, their spectra are remarkably different at the kinetic scale. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1255080-ion-driven-instabilities-solar-wind-wind-observations-march','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1255080-ion-driven-instabilities-solar-wind-wind-observations-march">Ion-driven instabilities in the solar wind: Wind observations of 19 March 2005</a> <a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a> Gary, S. Peter; Jian, Lan K.; Broiles, Thomas W.; ... 2016-01-16 Intervals of enhanced magnetic fluctuations have been frequently observed in the solar wind. However, it remains an open question as to whether these waves are generated at the Sun and then transported outward by the solar wind or generated locally in the interplanetary medium. Magnetic field and plasma measurements from the Wind spacecraft under slow solar wind conditions on 19 March 2005 demonstrate seven events of enhanced magnetic fluctuations at spacecraft-frame frequencies somewhat above the proton cyclotron frequency and propagation approximately parallel or antiparallel to the background magnetic field B o. The proton velocity distributions during these events are characterizedmore » by two components: a more dense, slower core and a less dense, faster beam. In conclusion, observed plasma parameters are used in a kinetic linear dispersion equation analysis for electromagnetic fluctuations at k x B o = 0; for two events the most unstable mode is the Alfvén-cyclotron instability driven by a proton component temperature anisotropy T ⊥/T || > 1 (where the subscripts denote directions relative to B o), and for three events the most unstable mode is the right-hand polarized magnetosonic instability driven primarily by ion component relative flows. Thus, both types of ion anisotropies and both types of instabilities are likely to be local sources of these enhanced fluctuation events in the solar wind.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1255080','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1255080">Ion-driven instabilities in the solar wind: Wind observations of 19 March 2005</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Gary, S. Peter; Jian, Lan K.; Broiles, Thomas W. Intervals of enhanced magnetic fluctuations have been frequently observed in the solar wind. However, it remains an open question as to whether these waves are generated at the Sun and then transported outward by the solar wind or generated locally in the interplanetary medium. Magnetic field and plasma measurements from the Wind spacecraft under slow solar wind conditions on 19 March 2005 demonstrate seven events of enhanced magnetic fluctuations at spacecraft-frame frequencies somewhat above the proton cyclotron frequency and propagation approximately parallel or antiparallel to the background magnetic field B o. The proton velocity distributions during these events are characterizedmore » by two components: a more dense, slower core and a less dense, faster beam. In conclusion, observed plasma parameters are used in a kinetic linear dispersion equation analysis for electromagnetic fluctuations at k x B o = 0; for two events the most unstable mode is the Alfvén-cyclotron instability driven by a proton component temperature anisotropy T ⊥/T || > 1 (where the subscripts denote directions relative to B o), and for three events the most unstable mode is the right-hand polarized magnetosonic instability driven primarily by ion component relative flows. Thus, both types of ion anisotropies and both types of instabilities are likely to be local sources of these enhanced fluctuation events in the solar wind.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27818854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27818854">Ion-driven instabilities in the solar wind: Wind observations of 19 March 2005.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Gary, S Peter; Jian, Lan K; Broiles, Thomas W; Stevens, Michael L; Podesta, John J; Kasper, Justin C 2016-01-01 Intervals of enhanced magnetic fluctuations have been frequently observed in the solar wind. But it remains an open question as to whether these waves are generated at the Sun and then transported outward by the solar wind or generated locally in the interplanetary medium. Magnetic field and plasma measurements from the Wind spacecraft under slow solar wind conditions on 19 March 2005 demonstrate seven events of enhanced magnetic fluctuations at spacecraft-frame frequencies somewhat above the proton cyclotron frequency and propagation approximately parallel or antiparallel to the background magnetic field B o . The proton velocity distributions during these events are characterized by two components: a more dense, slower core and a less dense, faster beam. Observed plasma parameters are used in a kinetic linear dispersion equation analysis for electromagnetic fluctuations at k x B o = 0; for two events the most unstable mode is the Alfvén-cyclotron instability driven by a proton component temperature anisotropy T ⊥ /T || > 1 (where the subscripts denote directions relative to B o ), and for three events the most unstable mode is the right-hand polarized magnetosonic instability driven primarily by ion component relative flows. Thus, both types of ion anisotropies and both types of instabilities are likely to be local sources of these enhanced fluctuation events in the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5070513','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5070513">Ion‐driven instabilities in the solar wind: Wind observations of 19 March 2005</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Jian, Lan K.; Broiles, Thomas W.; Stevens, Michael L.; Podesta, John J.; Kasper, Justin C. 2016-01-01 Abstract Intervals of enhanced magnetic fluctuations have been frequently observed in the solar wind. But it remains an open question as to whether these waves are generated at the Sun and then transported outward by the solar wind or generated locally in the interplanetary medium. Magnetic field and plasma measurements from the Wind spacecraft under slow solar wind conditions on 19 March 2005 demonstrate seven events of enhanced magnetic fluctuations at spacecraft‐frame frequencies somewhat above the proton cyclotron frequency and propagation approximately parallel or antiparallel to the background magnetic field B o. The proton velocity distributions during these events are characterized by two components: a more dense, slower core and a less dense, faster beam. Observed plasma parameters are used in a kinetic linear dispersion equation analysis for electromagnetic fluctuations at k x B o = 0; for two events the most unstable mode is the Alfvén‐cyclotron instability driven by a proton component temperature anisotropy T⊥/T|| > 1 (where the subscripts denote directions relative to B o), and for three events the most unstable mode is the right‐hand polarized magnetosonic instability driven primarily by ion component relative flows. Thus, both types of ion anisotropies and both types of instabilities are likely to be local sources of these enhanced fluctuation events in the solar wind. PMID:27818854 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P54C..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P54C..05K">Correlating Solar Wind Modulation with Ionospheric Variability at Mars from MEX and MAVEN Observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kopf, A. J.; Morgan, D. D.; Halekas, J. S.; Ruhunusiri, S.; Gurnett, D. A.; Connerney, J. E. P. 2017-12-01 The synthesis of observations by the Mars Express and Mars Atmosphere and Volatiles Evolution (MAVEN) spacecraft allows for a unique opportunity to study variability in the Martian ionosphere from multiple perspectives. One major source for this variability is the solar wind. Due to its elliptical orbit which precesses over time, MAVEN periodically spends part of its orbit outside the Martian bow shock, allowing for direct measurements of the solar wind impacting the Martian plasma environment. When the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument aboard Mars Express is simultaneously sounding the ionosphere, the influence from changes in the solar wind can be observed. Previous studies have suggested a positive correlation, connecting ionospheric density to the solar wind proton flux, but depended on Earth-based measurements for solar wind conditions. More recently, research has indicated that observations of ionospheric variability from these two spacecraft can be connected in special cases, such as shock wave impacts or specific solar wind magnetic field orientations. Here we extend this to more general solar wind conditions and examine how changes in the solar wind properties measured by MAVEN instruments correlate with ionospheric structure and dynamics observed simultaneously in MARSIS remote and local measurements. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021279&hterms=atmosphere+wind+profile&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Datmosphere%2Bwind%2Bprofile','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021279&hterms=atmosphere+wind+profile&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Datmosphere%2Bwind%2Bprofile">Elemental and charge state composition of the fast solar wind observed with SMS instruments on WIND</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gloeckler, G.; Galvin, A. B.; Ipavich, F. M.; Hamilton, D. C.; Bochsler, P.; Geiss, J.; Fisk, L. A.; Wilken, B. 1995-01-01 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820047282&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D80%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820047282&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D80%26Ntt%3Dlazarus">Voyager observations of solar wind proton temperature - 1-10 AU</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gazis, P. R.; Lazarus, A. J. 1982-01-01 Simultaneous measurements are made of the solar wind proton temperatures by the Voyager 1 and 2 spacecraft, far from earth, and the IMP 8 spacecraft in earth orbit. This technique permits a separation of radial and temporal variations of solar wind parameters. The average value of the proton temperature between 1 and 9 AU is observed to decrease as r (the heliocentric radius) to the -(0.7 + or - 0.2). This is slower than would be expected for adiabatic expansion. A detailed examination of the solar wind stream structure shows that considerable heating occurs at the interface between high and low speed streams. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018A%26A...611A..36V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018A%26A...611A..36V">Solar-wind predictions for the Parker Solar Probe orbit. Near-Sun extrapolations derived from an empirical solar-wind model based on Helios and OMNI observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Venzmer, M. S.; Bothmer, V. 2018-03-01 Context. The Parker Solar Probe (PSP; formerly Solar Probe Plus) mission will be humanitys first in situ exploration of the solar corona with closest perihelia at 9.86 solar radii (R⊙) distance to the Sun. It will help answer hitherto unresolved questions on the heating of the solar corona and the source and acceleration of the solar wind and solar energetic particles. The scope of this study is to model the solar-wind environment for PSPs unprecedented distances in its prime mission phase during the years 2018 to 2025. The study is performed within the Coronagraphic German And US SolarProbePlus Survey (CGAUSS) which is the German contribution to the PSP mission as part of the Wide-field Imager for Solar PRobe. Aim. We present an empirical solar-wind model for the inner heliosphere which is derived from OMNI and Helios data. The German-US space probes Helios 1 and Helios 2 flew in the 1970s and observed solar wind in the ecliptic within heliocentric distances of 0.29 au to 0.98 au. The OMNI database consists of multi-spacecraft intercalibrated in situ data obtained near 1 au over more than five solar cycles. The international sunspot number (SSN) and its predictions are used to derive dependencies of the major solar-wind parameters on solar activity and to forecast their properties for the PSP mission. Methods: The frequency distributions for the solar-wind key parameters, magnetic field strength, proton velocity, density, and temperature, are represented by lognormal functions. In addition, we consider the velocity distributions bi-componental shape, consisting of a slower and a faster part. Functional relations to solar activity are compiled with use of the OMNI data by correlating and fitting the frequency distributions with the SSN. Further, based on the combined data set from both Helios probes, the parameters frequency distributions are fitted with respect to solar distance to obtain power law dependencies. Thus an empirical solar-wind model for the inner </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070011610&hterms=lazarus&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070011610&hterms=lazarus&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlazarus">Solar Wind Proton Temperature Anisotropy: Linear Theory and WIND/SWE Observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hellinger, P.; Travnicek, P.; Kasper, J. C.; Lazarus, A. J. 2006-01-01 We present a comparison between WIND/SWE observations (Kasper et al., 2006) of beta parallel to p and T perpendicular to p/T parallel to p (where beta parallel to p is the proton parallel beta and T perpendicular to p and T parallel to p are the perpendicular and parallel proton are the perpendicular and parallel proton temperatures, respectively; here parallel and perpendicular indicate directions with respect to the ambient magnetic field) and predictions of the Vlasov linear theory. In the slow solar wind, the observed proton temperature anisotropy seems to be constrained by oblique instabilities, by the mirror one and the oblique fire hose, contrary to the results of the linear theory which predicts a dominance of the proton cyclotron instability and the parallel fire hose. The fast solar wind core protons exhibit an anticorrelation between beta parallel to c and T perpendicular to c/T parallel to c (where beta parallel to c is the core proton parallel beta and T perpendicular to c and T parallel to c are the perpendicular and parallel core proton temperatures, respectively) similar to that observed in the HELIOS data (Marsch et al., 2004). </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.6000S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.6000S">Interaction between Solar Wind and Lunar Magnetic Anomalies observed by Kaguya MAP-PACE</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Saito, Yoshifumi; Yokota, Shoichiro; Tanaka, Takaaki; Asamura, Kazushi; Nishino, Masaki; Yamamoto, Tadateru; Uemura, Kota; Tsunakawa, Hideo 2010-05-01 It is known that Moon has neither global intrinsic magnetic field nor thick atmosphere. Different from the Earth's case where the intrinsic global magnetic field prevents the solar wind from penetrating into the magnetosphere, solar wind directly impacts the lunar surface. Since the discovery of the lunar crustal magnetic field in 1960s, several papers have been published concerning the interaction between the solar wind and the lunar magnetic anomalies. MAG/ER on Lunar Prospector found heating of the solar wind electrons presumably due to the interaction between the solar wind and the lunar magnetic anomalies and the existence of the mini-magnetosphere was suggested. However, the detailed mechanism of the interaction has been unclear mainly due to the lack of the in-situ observed data of low energy ions. MAgnetic field and Plasma experiment - Plasma energy Angle and Composition Experiment (MAP-PACE) on Kaguya (SELENE) completed its ˜1.5-year observation of the low energy charged particles around the Moon on 10 June, 2009. Kaguya was launched on 14 September 2007 by H2A launch vehicle from Tanegashima Space Center in Japan. Kaguya was inserted into a circular lunar polar orbit of 100km altitude and continued observation for nearly 1.5 years till it impacted the Moon on 10 June 2009. During the last 5 months, the orbit was lowered to ˜50km-altitude between January 2009 and April 2009, and some orbits had further lower perilune altitude of ˜10km after April 2009. MAP-PACE consisted of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). All the sensors performed quite well as expected from the laboratory experiment carried out before launch. Since each sensor had hemispherical field of view, two electron sensors and two ion sensors that were installed on the spacecraft panels opposite to each other could cover full 3-dimensional phase space of low energy electrons and ions. One of the ion sensors IMA was </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li class="active">1</li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_2" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active">2</li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="21"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH53A2546J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH53A2546J">Lessons Learned from 10 Years of STEREO Solar Wind Observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jian, L. K.; Russell, C. T.; Luhmann, J. G.; Galvin, A. B. 2017-12-01 We have conducted long-term observations of large-scale solar wind structures since the launch of STEREO spacecraft, specifically interplanetary CMEs (ICMEs), slow-to-fast stream interaction regions (SIRs), and interplanetary shocks. In combination with our previous observations of the same solar wind structures in 1995-2009 using Wind/ACE data and the same identification criteria, we have first studied the solar cycle variations of these structures, especially for the same phases of solar cycles 23 and 24. Attributing the shocks to the interplanetary drivers, we have statistically compared the shocks driven by ICMEs and SIRs, and explained the shocks without a clear local driver. In addition, using the longitudinal and latitudinal separations between the twin spacecraft, we have investigated the recurrence and variability of ICMEs and SIRs, and gained the critical implications for the proposed L5 mission. At last, we have associated the heliospheric current sheet (HCS) crossings with the ICMEs and SIRs, and compared the properties of SIRs with and without HCS crossings, which correspond to the helmet streamers and pseudostreamers, respectively. The findings are important constraints on the theories of slow wind origin. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM41D2461N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM41D2461N">Diamagnetic effect in the foremoon solar wind observed by Kaguya</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nishino, M. N.; Saito, Y.; Tsunakawa, H.; Miyake, Y.; Harada, Y.; Yokota, S.; Takahashi, F.; Matsushima, M.; Shibuya, H.; Shimizu, H. 2016-12-01 Interaction between the lunar surface and incident solar wind is one of the crucial phenomena of the lunar plasma sciences. Recent observations by lunar orbiters revealed that strength of the interplanetary magnetic field (IMF) at spacecraft altitude increases over crustal magnetic fields on the dayside. In addition, variations of the IMF on the lunar night side have been reported in the viewpoint of diamagnetic effect around the lunar wake. However, few studies have been performed for the IMF over non-magnetized regions on the dayside. Here we show an event where strength of the IMF decreases at 100 km altitude on the lunar dayside (i.e. in the foremoon solar wind) when the IMF is almost parallel to the incident solar wind flow, comparing the upstream solar wind data from ACE and WIND with Kaguya magnetometer data. The lunar surface below the Kaguya orbit is not magnetized (or very weakly magnetized), and the sunward-travelling protons show signatures of those back-scattered at the lunar surface. We find that the decrease in the magnetic pressure is compensated by the thermal pressure of the back-scattered protons. In other words, the IMF strength in the foremoon solar wind decreases by diamagnetic effect of sunward-travelling protons back-scattered at the lunar dayside surface. Such diamagnetic effect would be prominent in the high-beta solar wind environment, and may be ubiquitous in the environment where planetary surface directly interacts with surrounding space plasma. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016A%26A...596A..42B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016A%26A...596A..42B">Mass-loading of the solar wind at 67P/Churyumov-Gerasimenko. Observations and modelling</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Behar, E.; Lindkvist, J.; Nilsson, H.; Holmström, M.; Stenberg-Wieser, G.; Ramstad, R.; Götz, C. 2016-11-01 Context. The first long-term in-situ observation of the plasma environment in the vicinity of a comet, as provided by the European Rosetta spacecraft. Aims: Here we offer characterisation of the solar wind flow near 67P/Churyumov-Gerasimenko (67P) and its long term evolution during low nucleus activity. We also aim to quantify and interpret the deflection and deceleration of the flow expected from ionization of neutral cometary particles within the undisturbed solar wind. Methods: We have analysed in situ ion and magnetic field data and combined this with hybrid modeling of the interaction between the solar wind and the comet atmosphere. Results: The solar wind deflection is increasing with decreasing heliocentric distances, and exhibits very little deceleration. This is seen both in observations and in modeled solar wind protons. According to our model, energy and momentum are transferred from the solar wind to the coma in a single region, centered on the nucleus, with a size in the order of 1000 km. This interaction affects, over larger scales, the downstream modeled solar wind flow. The energy gained by the cometary ions is a small fraction of the energy available in the solar wind. Conclusions: The deflection of the solar wind is the strongest and clearest signature of the mass-loading for a small, low-activity comet, whereas there is little deceleration of the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3627923','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3627923">Three-dimensional exploration of the solar wind using observations of interplanetary scintillation</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> TOKUMARU, Munetoshi 2013-01-01 The solar wind, 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 solar wind 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 solar wind. IPS measurements of the solar wind at a frequency of 327 MHz have been carried out regularly since the 1980s using the multi-station system of the Solar-Terrestrial Environment Laboratory (STEL) of Nagoya University. This paper reviews new aspects of the solar wind revealed from our IPS observations. PMID:23391604 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950015967','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950015967">Solar wind composition</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ogilvie, K. W.; Coplan, M. A. 1995-01-01 Advances in instrumentation have resulted in the determination of the average abundances of He, C, N, O, Ne, Mg, Si, S, and Fe in the solar wind to approximately 10%. Comparisons with solar energetic particle (SEP) abundances and galactic cosmic ray abundances have revealed many similarities, especially when compared with solar photospheric abundances. It is now well established that fractionation in the corona results in an overabundance (with respect to the photosphere) of elements with first ionization potentials less than 10 eV. These observations have in turn led to the development of fractionation models that are reasonably successful in reproducing the first ionization (FIP) effect. Under some circumstances it has been possible to relate solar wind observations to particular source regions in the corona. The magnetic topologies of the source regions appear to have a strong influence on the fractionation of elements. Comparisons with spectroscopic data are particularly useful in classifying the different topologies. Ions produced from interstellar neutral atoms are also found in the solar wind. These ions are picked up by the solar wind after ionization by solar radiation or charge exchange and can be identified by their velocity in the solar wind. The pick-up ions provide most of the pressure in the interplanetary medium at large distances. Interstellar abundances can be derived from the observed fluxes of solar wind pick-up ions. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021428&hterms=micro+wind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmicro%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021428&hterms=micro+wind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmicro%2Bwind">Observations of micro-turbulence in the solar wind near the sun with interplanetary scintillation</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Yamauchi, Y.; Misawa, H.; Kojima, M.; Mori, H.; Tanaka, T.; Takaba, H.; Kondo, T.; Tokumaru, M.; Manoharan, P. K. 1995-01-01 Velocity and density turbulence of solar wind were inferred from interplanetary scintillation (IPS) observations at 2.3 GHz and 8.5 GHz using a single-antenna. The observations were made during September and October in 1992 - 1994. They covered the distance range between 5 and 76 solar radii (Rs). We applied the spectrum fitting method to obtain a velocity, an axial ratio, an inner scale and a power-law spectrum index. We examined the difference of the turbulence properties near the Sun between low-speed solar wind and high-speed solar wind. Both of solar winds showed acceleration at the distance range of 10 - 30 Rs. The radial dependence of anisotropy and spectrum index did not have significant difference between low-speed and high-speed solar winds. Near the sun, the radial dependence of the inner scale showed the separation from the linear relation as reported by previous works. We found that the inner scale of high-speed solar wind is larger than that of low-speed wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5995N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5995N">Diamagnetic effect in the foremoon solar wind observed by Kaguya</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nishino, Masaki N.; Saito, Yoshifumi; Tsunakawa, Hideo; Miyake, Yohei; Harada, Yuki; Yokota, Shoichiro; Takahashi, Futoshi; Matsushima, Masaki; Shibuya, Hidetoshi; Shimizu, Hisayoshi 2017-04-01 Direct interaction between the lunar surface and incident solar wind is one of the crucial phenomena of the planetary plasma sciences. Recent observations by lunar orbiters revealed that strength of the interplanetary magnetic field (IMF) at spacecraft altitude often increases over crustal magnetic fields on the dayside. In addition, variations of the IMF on the lunar night side have been reported in the viewpoint of diamagnetic effect around the lunar wake. However, few studies have been performed for the IMF over non-magnetized regions on the dayside. Here we show an event where strength of the IMF decreases at 100 km altitude on the lunar dayside (i.e. in the foremoon solar wind) when the IMF is almost parallel to the incident solar wind flow, comparing the upstream solar wind data from ACE with Kaguya magnetometer data. The lunar surface below the Kaguya orbit is not magnetized (or very weakly magnetized), and the sunward-travelling protons show signatures of those back-scattered at the lunar surface. We find that the decrease in the magnetic pressure is compensated by the thermal pressure of the back-scattered protons. In other words, the IMF strength in the foremoon solar wind decreases by diamagnetic effect of sunward-travelling protons back-scattered at the lunar dayside surface. Such an effect would be prominent in the high-beta solar wind, and may be ubiquitous in the environment where planetary surface directly interacts with surrounding space plasma. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22086330-ace-swics-observations-heavy-ion-dropouts-within-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22086330-ace-swics-observations-heavy-ion-dropouts-within-solar-wind">ACE/SWICS OBSERVATIONS OF HEAVY ION DROPOUTS WITHIN THE SOLAR WIND</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Weberg, Micah J.; Zurbuchen, Thomas H.; Lepri, Susan T., E-mail: mjweberg@umich.edu, E-mail: thomasz@umich.edu, E-mail: slepri@umich.edu 2012-11-20 We present the first in situ observations of heavy ion dropouts within the slow solar wind, observed for select elements ranging from helium to iron. For iron, these dropouts manifest themselves as depletions of the Fe/H ratio by factors up to {approx}25. The events often exhibit mass-dependent fractionation and are contained in slow, unsteady wind found within a few days from known stream interfaces. We propose that such dropouts are evidence of gravitational settling within large coronal loops, which later undergo interchange reconnection and become source regions of slow, unsteady wind. Previously, spectroscopic studies by Raymond et al. in 1997more » (and later Feldman et al. in 1999) have yielded strong evidence for gravitational settling within these loops. However, their expected in situ signature plasma with heavy elements fractionated by mass was not observed prior to this study. Using data from the SWICS instrument on board the Advanced Composition Explorer (ACE), we investigate the composition of the solar wind within these dropouts and explore long term trends over most of a solar cycle.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM11B2312S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM11B2312S">Vortex, ULF wave and Aurora Observation after Solar Wind Dynamic Pressure Change</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shi, Q. 2017-12-01 Here we will summarize our recent study and show some new results on the Magnetosphere and Ionosphere Response to Dynamic Pressure Change/disturbances in the Solar Wind and foreshock regions. We study the step function type solar wind dynamic pressure change (increase/decrease) interaction with the magnetosphere using THEMIS satellites at both dayside and nightside in different geocentric distances. Vortices generated by the dynamic pressure change passing along the magnetopause are found and compared with model predictions. ULF waves and vortices are excited in the dayside and nightside plasma sheet when dynamic pressure change hit the magnetotail. The related ionospheric responses, such as aurora and TCVs, are also investigated. We compare Global MHD simulations with the observations. We will also show some new results that dayside magnetospheric FLRs might be caused by foreshock structures.Shi, Q. Q. et al. (2013), THEMIS observations of ULF wave excitation in the nightside plasma sheet during sudden impulse events, J. Geophys. Res. Space Physics, 118, doi:10.1029/2012JA017984. Shi, Q. Q. et al. (2014), Solar wind pressure pulse-driven magnetospheric vortices and their global consequences, J. Geophys. Res. Space Physics, 119, doi:10.1002/2013JA019551. Tian, A.M. et al.(2016), Dayside magnetospheric and ionospheric responses to solar wind pressure increase: Multispacecraft and ground observations, J. Geophys. Res., 121, doi:10.1002/2016JA022459. Shen, X.C. et al.(2015), Magnetospheric ULF waves with increasing amplitude related to solar wind dynamic pressure changes: THEMIS observations, J. Geophys. Res., 120, doi:10.1002/2014JA020913Zhao, H. Y. et al. (2016), Magnetospheric vortices and their global effect after a solar wind dynamic pressure decrease, J. Geophys. Res. Space Physics, 121, doi:10.1002/2015JA021646. Shen, X. C., et al. (2017), Dayside magnetospheric ULF wave frequency modulated by a solar wind dynamic pressure negative impulse, J. Geophys. Res </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4354106','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4354106">Full-Sun observations for identifying the source of the slow solar wind</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Brooks, David H.; Ugarte-Urra, Ignacio; Warren, Harry P. 2015-01-01 Fast (>700 km s−1) and slow (~400 km s−1) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind. PMID:25562705 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930049592&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D60%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930049592&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D60%26Ntt%3Dlazarus">Solar wind temperature observations in the outer heliosphere</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J. 1992-01-01 The Pioneer 10, Pioneer 11, and Voyager 2 spacecraft are now at heliocentric distances of 50, 32 and 33 AU, and heliographic latitudes of 3.5 deg N, 17 deg N, and 0 deg N, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer l0 is on the opposite side of the sun. The baselines defined by these spacecraft make it possible to resolve radial, longitudinal, and latitudinal variations of solar wind parameters. The solar wind temperature decreases with increasing heliocentric distance out to a distance of 10-15 AU. At larger heliocentric distances, this gradient disappears. These high solar wind temperatures in the outer heliosphere have persisted for at least 10 years, which suggests that they are not a solar cycle effect. The solar wind temperature varied with heliographic latitude during the most recent solar minimum. The solar wind temperature at Pioneer 11 and Voyager 2 was higher than that seen at Pioneer 10 for an extended period of time, which suggests the existence of a large-scale variation of temperature with celestial longitude, but the contribution of transient phenomena is yet to be clarified. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003114&hterms=Wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DWind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003114&hterms=Wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DWind">Slow Solar Wind: Observations and Modeling</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Abbo, L.; Ofman, L.; Antiochos, S. K.; Hansteen, V. H.; Harra, L.; Ko, Y.-K.; Lapenta, G.; Li, B.; Riley, P.; Strachan, L.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170003114'); toggleEditAbsImage('author_20170003114_show'); toggleEditAbsImage('author_20170003114_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170003114_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170003114_hide"> 2016-01-01 While it is certain that the fast solar wind originates from coronal holes, where and how the slow solar wind (SSW) is formed remains an outstanding question in solar physics even in the post-SOHO era. The quest for the SSW origin forms a major objective for the planned future missions such as the Solar Orbiter and Solar Probe Plus. Nonetheless, results from spacecraft data, combined with theoretical modeling, have helped to investigate many aspects of the SSW. Fundamental physical properties of the coronal plasma have been derived from spectroscopic and imaging remote-sensing data and in situ data, and these results have provided crucial insights for a deeper understanding of the origin and acceleration of the SSW. Advanced models of the SSW in coronal streamers and other structures have been developed using 3D MHD and multi-fluid equations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P51C2600L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P51C2600L">Analysis of Solar Wind Precipitation on Mars Using MAVEN/SWIA Observations of Spacecraft-Scattered Ions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lue, C.; Halekas, J. S. 2017-12-01 Particle sensors on the MAVEN spacecraft (SWIA, SWEA, STATIC) observe precipitating solar wind ions during MAVEN's periapsis passes in the Martian atmosphere (at 120-250 km altitude). The signature is observed as positive and negative particles at the solar wind energy, traveling away from the Sun. The observations can be explained by the solar wind penetrating the Martian magnetic barrier in the form of energetic neutral atoms (ENAs) due to charge-exchange with the Martian hydrogen corona, and then being reionized in positive or negative form upon impact with the atmosphere (1). These findings have elucidated solar wind precipitation dynamics at Mars, and can also be used to monitor the solar wind even when MAVEN is at periapsis (2). In the present study, we focus on a SWIA instrument background signal that has been interpreted as spacecraft/instrument-scattered ions (2). We aim to model and subtract the scattered ion signal from the observations including those of reionized solar wind. We also aim to use the scattered ion signal to track hydrogen ENAs impacting the spacecraft above the reionization altitude. We characterize the energy spectrum and directional scattering function for solar wind scattering off the SWIA aperture structure, the radome and the spacecraft body. We find a broad scattered-ion energy spectrum up to the solar wind energy, displaying increased energy loss and reduced flux with increasing scattering angle, allowing correlations with the solar wind direction, energy, and flux. We develop models that can be used to predict the scattered signal based on the direct solar wind observations or to infer the solar wind properties based on the observed scattered signal. We then investigate deviations to the models when the spacecraft is in the Martian atmosphere and evaluate the plausibility of that these are caused by ENAs. We also perform SIMION modeling of the scattering process and the resulting signal detection by SWIA, to study the results from </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930004279','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930004279">Observations of solar wind ion charge exchange in the comet Halley coma</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Fuselier, S. A.; Shelley, E. G.; Goldstein, B. E.; Goldstein, R.; Neugebauer, M.; Ip, W.-H.; Balsiger, H.; Reme, H. 1991-01-01 Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of comet Halley. As the comet was approached, the He(++) to proton density ratio increased until about 1 hour before closest approach after which time it decreased. Abrupt increases in this ratio were also observed in the beginning and near the end of the so-called Mystery Region (8.6 - 5.5(10)(exp 5) km from the comet along the spacecraft trajectory). These abrupt increases in the density ratio were well correlated with enhanced fluxes of keV electrons as measured by the Giotto plasma electron spectrometer. The general increase and then decrease of the He(++) to proton density ratio is quantitatively consistent with a combination of the addition of protons of cometary origin to the plasma and loss of plasma through charge exchange of protons and He(++). In general agreement with the solar wind proton and He(++) observations, solar wind oxygen and carbon ions were observed to charge exchange from higher to lower charge states with decreasing distance to the comet. The more abrupt increases in the He(++) to proton and the He(++) to O(6+) density ratios in the mystery region require a change in the solar wind ion composition in this region while the correlation with energetic electrons indicates processes associated with the comet. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030025688','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030025688">Wind Observations of Anomalous Cosmic Rays from Solar Minimum to Maximum</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Reames, D. V.; McDonald, F. B. 2003-01-01 We report the first observation near Earth of the time behavior of anomalous cosmic-ray N, O, and Ne ions through the period surrounding the maximum of the solar cycle. These observations were made by the Wind spacecraft during the 1995-2002 period spanning times from solar minimum through solar maximum. Comparison of anomalous and galactic cosmic rays provides a powerful tool for the study of the physics of solar modulation throughout the solar cycle. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22126712-hemispheric-asymmetries-polar-solar-wind-observed-ulysses-near-minima-solar-cycles','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22126712-hemispheric-asymmetries-polar-solar-wind-observed-ulysses-near-minima-solar-cycles">HEMISPHERIC ASYMMETRIES IN THE POLAR SOLAR WIND OBSERVED BY ULYSSES NEAR THE MINIMA OF SOLAR CYCLES 22 AND 23</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Ebert, R. W.; Dayeh, M. A.; Desai, M. I. 2013-05-10 We examined solar wind plasma and interplanetary magnetic field (IMF) observations from Ulysses' first and third orbits to study hemispheric differences in the properties of the solar wind and IMF originating from the Sun's large polar coronal holes (PCHs) during the declining and minimum phase of solar cycles 22 and 23. We identified hemispheric asymmetries in several parameters, most notably {approx}15%-30% south-to-north differences in averages for the solar wind density, mass flux, dynamic pressure, and energy flux and the radial and total IMF magnitudes. These differences were driven by relatively larger, more variable solar wind density and radial IMF betweenmore » {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.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH14B..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH14B..03M">Do In Situ Observations Contain Signatures of Intermittent Fast Solar Wind Acceleration?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Matteini, L.; Horbury, T. S.; Stansby, D. 2017-12-01 Disentangling local plasma properties and Solar origin structures in in situ data is a crucial aspect for the understanding of solar wind acceleration and evolution. This is particularly challenging at 1 AU and beyond, where structures of various origin have had time to interact and merge, smoothing out their main characteristics. Observations of more pristine plasma closer to the Sun are therefore needed. In preparation of the forthcoming Solar Orbiter and Parker Solar Probe missions, Helios observations as close as to 0.3 AU - although old, not yet fully exploited - can be used to test our expectations and make new predictions. Recent observations (Matteini et al. 2014, 2015) have outlined the presence of intense (up to 1000km/s) and short-living velocity peaks that ubiquitously characterize the typical profile of the fast solar wind at 0.3 AU, suggesting that these features could be remnants of processes occurring in the Solar atmosphere and a signature of intermittent solar wind acceleration from coronal holes. We discuss results about statistics of these events, characterizing their physical properties and trying to link them with typical Solar temporal and spatial scales. Finally we also discuss how these velocity peaks will likely affect the future in situ exploration of the inner heliosphere by Solar Orbiter and the Parker Solar Probe. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021396&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddropout','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021396&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddropout">Suprathermal electron loss cone distributions in the solar wind: Ulysses observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Phillips, J. L.; Feldman, W. C.; Gosling, J. T.; Hammond, C. M.; Forsyth, R. J. 1995-01-01 Solar wind suprathermal electron distributions in the solar wind generally carry a field-aligned antisunward heat flux. Within coronal mass ejections and upstream of strong shocks driven by corotating interaction regions (CIRs), counterstreaming electron beams are observed. We present observations by the Ulysses solar wind plasma experiment of a new class of suprathermal electron signatures. At low solar latitudes and heliocentric distances beyond 3.5 AU Ulysses encountered several intervals, ranging in duration from 1 hour to 22 hours, in which the suprathermal distributions included an antisunward field-aligned beam and a return population with a flux dropout typically spanning +/- 60 deg from the sunward field-aligned direction. All events occurred within CIRs, downstream of the forward and reverse shocks or waves bounding the interaction regions. We evaluate the hypothesis that the sunward-moving electrons result from reflection of the antisunward beams at magnetic field compressions downstream from the observations, with wide loss cones caused by the relatively weak compression ratio. This hypothesis requires that field magnitude within the CIRs actually increase with increasing field-aligned distance from the Sun. Details of the electron distributions and ramifications for CIR and shock geometry will be presented. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38..419S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38..419S">Interaction between solar wind and lunar magnetic anomalies observed by MAP-PACE on Kaguya</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Saito, Yoshifumi; Yokota, Shoichiro; Tanaka, Takaaki; Asamura, Kazushi; Nishino, Masaki N.; Yamamoto, Tadateru I.; Tsunakawa, Hideo It is well known that the Moon has neither global intrinsic magnetic field nor thick atmosphere. Different from the Earth's case where the intrinsic global magnetic field prevents the solar wind from penetrating into the magnetosphere, solar wind directly impacts the lunar surface. MAgnetic field and Plasma experiment -Plasma energy Angle and Composition Experiment (MAP-PACE) on Kaguya (SELENE) completed its 1.5-year observation of the low energy charged particles around the Moon on 10 June 2009. Kaguya was launched on 14 September 2007 by H2A launch vehicle from Tanegashima Space Center in Japan. Kaguya was inserted into a circular lunar polar orbit of 100km altitude and continued observation for nearly 1.5 years till it impacted the Moon on 10 June 2009. During the last 5 months, the orbit was lowered to 50km-altitude between January 2009 and April 2009, and some orbits had further lower perilune altitude of 10km after April 2009. MAP-PACE consisted of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). Since each sensor had hemispherical field of view, two electron sensors and two ion sensors that were installed on the spacecraft panels opposite to each other could cover full 3-dimensional phase space of low energy electrons and ions. One of the ion sensors IMA was an energy mass spectrometer. IMA measured mass identified ion energy spectra that had never been obtained at 100km altitude polar orbit around the Moon. When Kaguya flew over South Pole Aitken region, where strong magnetic anomalies exist, solar wind ions reflected by magnetic anomalies were observed. These ions had much higher flux than the solar wind protons scattered at the lunar surface. The magnetically reflected ions had nearly the same energy as the incident solar wind ions while the solar wind protons scattered at the lunar surface had slightly lower energy than the incident solar wind ions. At 100km altitude, when the reflected ions </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003051&hterms=Mysteries&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DMysteries','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003051&hterms=Mysteries&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DMysteries">Implications of L1 Observations for Slow Solar Wind Formation by Solar Reconnection</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kepko, L.; Viall, N. M.; Antiochos, S. K.; Lepri, S. T.; Kasper, J. C.; Weberg, M. 2016-01-01 While the source of the fast solar wind is known to be coronal holes, the source of the slow solar wind has remained a mystery. Long time scale trends in the composition and charge states show strong correlations between solar wind velocity and plasma parameters, yet these correlations have proved ineffective in determining the slow wind source. We take advantage of new high time resolution (12 min) measurements of solar wind composition and charge state abundances at L1 and previously identified 90 min quasi periodic structures to probe the fundamental timescales of slow wind variability. The combination of new high temporal resolution composition measurements and the clearly identified boundaries of the periodic structures allows us to utilize these distinct solar wind parcels as tracers of slowwind origin and acceleration. We find that each 90 min (2000 Mm) parcel of slow wind has near-constant speed yet exhibits repeatable, systematic charge state and composition variations that span the entire range of statistically determined slow solar wind values. The classic composition-velocity correlations do not hold on short, approximately hour long, time scales. Furthermore, the data demonstrate that these structures were created by magnetic reconnection. Our results impose severe new constraints on slow solar wind origin and provide new, compelling evidence that the slow wind results from the sporadic release of closed field plasma via magnetic reconnection at the boundary between open and closed flux in the Sun's atmosphere. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active">2</li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_3" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active">3</li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="41"> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900049938&hterms=SMM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSMM','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900049938&hterms=SMM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSMM">Solar wind and coronal structure near sunspot minimum - Pioneer and SMM observations from 1985-1987</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Mihalov, J. D.; Barnes, A.; Hundhausen, A. J.; Smith, E. J. 1990-01-01 Changes in solar wind speed and magnetic polarity observed at the Pioneer spacecraft are discussed here in terms of the changing magnetic geometry implied by SMM coronagraph observations over the period 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations during this epoch show a systematic variation in coronal structure and the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet, and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.9815K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.9815K">Applying Nyquist's method for stability determination to solar wind observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Klein, Kristopher G.; Kasper, Justin C.; Korreck, K. E.; Stevens, Michael L. 2017-10-01 The role instabilities play in governing the evolution of solar and astrophysical plasmas is a matter of considerable scientific interest. The large number of sources of free energy accessible to such nearly collisionless plasmas makes general modeling of unstable behavior, accounting for the temperatures, densities, anisotropies, and relative drifts of a large number of populations, analytically difficult. We therefore seek a general method of stability determination that may be automated for future analysis of solar wind observations. This work describes an efficient application of the Nyquist instability method to the Vlasov dispersion relation appropriate for hot, collisionless, magnetized plasmas, including the solar wind. The algorithm recovers the familiar proton temperature anisotropy instabilities, as well as instabilities that had been previously identified using fits extracted from in situ observations in Gary et al. (2016). Future proposed applications of this method are discussed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4820607N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4820607N">Small is different: RPC observations of a small scale comet interacting with the solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nilsson, Hans; Burch, James L.; Carr, Christopher M.; Eriksson, Anders I.; Glassmeier, Karl-Heinz; Henri, Pierre; Rosetta Plasma Consortium Team 2016-10-01 Rosetta followed comet 67P from low activity at more than 3 AU heliocentric distance to peak activity at perihelion and then out again. We study the evolution of the dynamic plasma environment using data from the Rosetta Plasma Consortium (RPC). Observations of cometary plasma began in August 2014, at a distance of 100 km from the comet nucleus and at 3.6 AU from the Sun. As the comet approached the Sun, outgassing from the comet increased, as did the density of the cometary plasma. Measurements showed a highly heterogeneous cold ion environment, permeated by the solar wind. The solar wind was deflected due to the mass loading from newly added cometary plasma, with no discernible slowing down. The magnetic field magnitude increased significantly above the background level, and strong low frequency waves were observed in the magnetic field, a.k.a. the "singing comet". Electron temperatures were high, leading to a frequently strongly negative spacecraft potential. In mid to late April 2015 the solar wind started to disappear from the observation region. This was associated with a solar wind deflection reaching nearly 180°, indicating that mass loading became efficient enough to form a solar wind-free region. Accelerated water ions, moving mainly in the anti-sunward direction, kept being observed also after the solar wind disappearance. Plasma boundaries began to form and a collisionopause was tentatively identified in the ion and electron data. At the time around perihelion, a diamagnetic cavity was also observed, at a surprisingly large distance from the comet. In late 2016 the solar wind re-appeared at the location of Rosetta, allowing for studies of asymmetry of the comet ion environment with respect to perihelion. A nightside excursion allowed us to get a glimpse of the electrodynamics of the innermost part of the plasma tail. Most of these phenomena are dependent on the small-scale physics of comet 67P, since for most of the Rosetta mission the solar wind </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120016043','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120016043">ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20120016043'); toggleEditAbsImage('author_20120016043_show'); toggleEditAbsImage('author_20120016043_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20120016043_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20120016043_hide"> 2012-01-01 We analyze the ROSAT PSPC soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the count rate in three wedges, two wedges (one north and one south) 13-32 degrees off (19 degrees wide) the terminator towards the dark side and one wedge 38 degrees wide centered on the anti-solar direction. The radial profiles of both the north and the south wedges show substantial limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the count rate increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere. Along with Mars, Venus, and Earth, the Moon represents another solar system body at which solar wind charge exchange has been observed. This technique can be used to explore the solar wind-lunar interaction. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021392&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021392&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dwind%2Bmonitor">SWICS/Ulysses and MASS/wind observations of solar wind sulfur charge states</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Cohen, C. M. S.; Galvin, A. B.; Hamilton, D. C.; Gloeckler, G.; Geiss, J.; Bochsler, P. 1995-01-01 As Ulysses journeys from the southern to the northern solar pole, the newly launched Wind spacecraft is monitoring the solar wind near 1 AU, slightly upstream of the Earth. Different solar wind structures pass over both spacecraft as coronal holes and other features rotate in and out of view. Ulysses and Wind are presently on opposing sides of the sun allowing us to monitor these streams for extended periods of time. Composition measurements made by instruments on both spacecraft provide information concerning the evolution and properties of these structures. We have combined data from the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses and the high mass resolution spectrometer (MASS) on Wind to determine the charge state distribution of sulfur in the solar wind. Both instruments employ electrostatic deflection with time-of-flight measurement. The high mass resolution of the MASS instrument (M/Delta-M approximately 100) allows sulfur to be isolated easily while the stepping energy/charge selection provides charge state information. SWICS measurements allow the unique identification of heavy ions by their mass and mass/charge with resolutions of M/Delta-M approximately 3 and M/q/Delta(M/q) approximately 20. The two instruments complement each other nicely in that MASS has the greater mass resolution while SWICS has the better mass/charge resolution and better statistics. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020086296','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020086296">Investigation of Solar Wind Correlations and Solar Wind Modifications Near Earth by Multi-Spacecraft Observations: IMP 8, WIND and INTERBALL-1</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Paularena, Karolen I.; Richardson, John D.; Zastenker, Georgy N. 2002-01-01 The foundation of this Project is use of the opportunity available during the ISTP (International Solar-Terrestrial Physics) era to compare solar wind measurements obtained simultaneously by three spacecraft - IMP 8, WIND and INTERBALL-1 at wide-separated points. Using these data allows us to study three important topics: (1) the size and dynamics of near-Earth mid-scale (with dimension about 1-10 million km) and small-scale (with dimension about 10-100 thousand km) solar wind structures; (2) the reliability of the common assumption that solar wind conditions at the upstream Lagrangian (L1) point accurately predict the conditions affecting Earth's magnetosphere; (3) modification of the solar wind plasma and magnetic field in the regions near the Earth magnetosphere, the foreshock and the magnetosheath. Our Project was dedicated to these problems. Our research has made substantial contributions to the field and has lead others to undertake similar work. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH51D2537S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH51D2537S">Solar wind structure out of the ecliptic plane over solar cycles</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sokol, J. M.; Bzowski, M.; Tokumaru, M. 2017-12-01 Sun constantly emits a stream of plasma known as solar wind. Ground-based observations of the solar wind speed through the interplanetary scintillations (IPS) of radio flux from distant point sources and in-situ measurements by Ulysses mission revealed that the solar wind flow has different characteristics depending on the latitude. This latitudinal structure evolves with the cycle of solar activity. The knowledge on the evolution of solar wind structure is important for understanding the interaction between the interstellar medium surrounding the Sun and the solar wind, which is responsible for creation of the heliosphere. The solar wind structure must be taken into account in interpretation of most of the observations of heliospheric energetic neutral atoms, interstellar neutral atoms, pickup ions, and heliospheric backscatter glow. The information on the solar wind structure is not any longer available from direct measurements after the termination of Ulysses mission and the only source of the solar wind out of the ecliptic plane is the IPS observations. However, the solar wind structure obtained from this method contains inevitable gaps in the time- and heliolatitude coverage. Sokół et al 2015 used the solar wind speed data out of the ecliptic plane retrieved from the IPS observations performed by Institute for Space-Earth Environmental Research (Nagoya University, Japan) and developed a methodology to construct a model of evolution of solar wind speed and density from 1985 to 2013 that fills the data gaps. In this paper we will present a refined model of the solar wind speed and density structure as a function of heliographic latitude updated by the most recent data from IPS observations. And we will discuss methods of extrapolation of the solar wind structure out of the ecliptic plane for the past solar cycles, when the data were not available, as well as forecasting for few years upward. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890045672&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D90%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890045672&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D90%26Ntt%3Dlazarus">Pioneer and Voyager observations of the solar wind at large heliocentric distances and latitudes</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gazis, P. R.; Mihalov, J. D.; Barnes, A.; Lazarus, A. J.; Smith, E. J. 1989-01-01 Data obtained from the electrostatic analyzers aboard the Pioneer 10 and 11 spacecraft and from the Faraday cup aboard Voyager 2 were used to study spatial gradients in the distant solar wind. Prior to mid-1985, both spacecraft observed nearly identical solar wind structures. After day 150 of 1985, the velocity structure at Voyager 2 became flatter, and the Voyager 2 velocities were smaller than those observed by Pioneer 11. It is suggested that these changes in the solar wind at low latitudes may be related to a change which occurred in the coronal hole structure in early 1985. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH23D2703P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH23D2703P">The Solar Wind from Pseudostreamers and their Environs: Opportunities for Observations with Parker Solar Probe and Solar Orbiter</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Panasenco, O.; Velli, M.; Panasenco, A.; Lionello, R. 2017-12-01 The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Mid-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of pseudostreamers shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at thepseudostreamer base low in the corona. We review and model possible coronal magnetic configurations and solar wind plasma properties at different distances from the solar surface that </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PPCF...56f4008E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PPCF...56f4008E">On the signatures of magnetic islands and multiple X-lines in the solar wind as observed by ARTEMIS and WIND</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Eriksson, S.; Newman, D. L.; Lapenta, G.; Angelopoulos, V. 2014-06-01 We report the first observation consistent with a magnetic reconnection generated magnetic island at a solar wind current sheet that was observed on 10 June 2012 by the two ARTEMIS satellites and the upstream WIND satellite. The evidence consists of a core magnetic field within the island which is formed by enhanced Hall magnetic fields across a solar wind reconnection exhaust. The core field at ARTEMIS displays a local dip coincident with a peak plasma density enhancement and a locally slower exhaust speed which differentiates it from a regular solar wind exhaust crossing. Further indirect evidence of magnetic island formation is presented in the form of a tripolar Hall magnetic field, which is supported by an observed electron velocity shear, and plasma density depletion regions which are in general agreement with multiple reconnection X-line signatures at the same current sheet on the basis of predicted signatures of magnetic islands as generated by a kinetic reconnection simulation for solar wind-like conditions. The combined ARTEMIS and WIND observations of tripolar Hall magnetic fields across the same exhaust and Grad-Shrafranov reconstructions of the magnetic field suggest that an elongated magnetic island was encountered which displayed a 4RE normal width and a 43RE extent along the exhaust between two neighboring X-lines. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...856L..10M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...856L..10M">Heliosphere Responds to a Large Solar Wind Intensification: Decisive Observations from IBEX</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> McComas, D. J.; Dayeh, M. A.; Funsten, H. O.; Heerikhuisen, J.; Janzen, P. H.; Reisenfeld, D. B.; Schwadron, N. A.; Szalay, J. R.; Zirnstein, E. J. 2018-03-01 Our heliosphere—the bubble in the local interstellar medium produced by the Sun’s outflowing solar wind—has finally responded to a large increase in solar wind output and pressure in the second half of 2014. NASA’s Interstellar Boundary Explorer (IBEX) mission remotely monitors the outer heliosphere by observing energetic neutral atoms (ENAs) returning from the heliosheath, the region between the termination shock and heliopause. IBEX observed a significant enhancement in higher energy ENAs starting in late 2016. While IBEX observations over the previous decade reflected a general reduction of ENA intensities, indicative of a deflating heliosphere, new observations show that the large (∼50%), persistent increase in the solar wind dynamic pressure has modified the heliosheath, producing enhanced ENA emissions. The combination of these new observations with simulation results indicate that this pressure is re-expanding our heliosphere, with the termination shock and heliopause already driven outward in the locations closest to the Sun. The timing between the IBEX observations, a large transient pressure enhancement seen by Voyager 2, and the simulations indicates that the pressure increase propagated through the heliosheath, reflected off the heliopause, and the enhanced density of the solar wind filled the heliosheath behind it before generating significantly enhanced ENA emissions. The coming years should see significant changes in anomalous cosmic rays, galactic cosmic radiation, and the filtration of interstellar neutral atoms into the inner heliosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750045079&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dorbiting%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750045079&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dorbiting%2Bwind">Direct observations of a flare related coronal and solar wind disturbance</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gosling, J. T.; Hildner, E.; Macqueen, R. M.; Munro, R. H.; Poland, A. I.; Ross, C. L. 1975-01-01 Numerous mass ejections from the sun have been detected with orbiting coronagraphs. Here for the first time we document and discuss the direct association of a coronagraph observed mass ejection, which followed a 2B flare, with a large interplanetary shock wave disturbance observed at 1 AU. Estimates of the mass and energy content of the coronal disturbance are in reasonably good agreement with estimates of the mass and energy content of the solar wind disturbance at 1 AU. The energy estimates as well as the transit time of the disturbance are also in good agreement with numerical models of shock wave propagation in the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH21C..05V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH21C..05V">Combining Remote and In Situ Observations with MHD models to Understand the Formation of the Slow Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Viall, N. M.; Kepko, L.; Antiochos, S. K.; Lepri, S. T.; Vourlidas, A.; Linker, J. 2017-12-01 Connecting the structure and variability in the solar corona to the Heliosphere and solar wind is one of the main goals of Heliophysics and space weather research. The instrumentation and viewpoints of the Parker Solar Probe and Solar Orbiter missions will provide an unprecedented opportunity to combine remote sensing with in situ data to determine how the corona drives the Heliosphere, especially as it relates to the origin of the slow solar wind. We present analysis of STEREO coronagraph and heliospheric imager observations and of in situ ACE and Wind measurements that reveal an important connection between the dynamics of the corona and of the solar wind. We show observations of quasi-periodic release of plasma into the slow solar wind occurring throughout the corona - including regions away from the helmet streamer and heliospheric current sheet - and demonstrate that these observations place severe constraints on the origin of the slow solar wind. We build a comprehensive picture of the dynamic evolution by combining remote imaging data, in situ composition and magnetic connectivity information, and MHD models of the solar wind. Our results have critical implications for the magnetic topology involved in slow solar wind formation and magnetic reconnection dynamics. Crucially, this analysis pushes the limits of current instrument resolution and sensitivity, showing the enormous potential science to be accomplished with the Parker Solar Probe and Solar Orbiter missions. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900063357&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbackground%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900063357&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbackground%2Bwind">Solar minimum Lyman alpha sky background observations from Pioneer Venus orbiter ultraviolet spectrometer - Solar wind latitude variation</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ajello, J. M. 1990-01-01 Measurements of interplanetary H I Lyman alpha over a large portion of the celestial sphere were made at the recent solar minimum by the Pioneer Venus orbiter ultraviolet spectrometer. These measurements were performed during a series of spacecraft maneuvers conducted to observe Halley's comet in early 1986. Analysis of these data using a model of the passage of interstellar wind hydrogen through the solar system shows that the rate of charge exchange with solar wind protons is 30 percent less over the solar poles than in the ecliptic. This result is in agreement with a similar experiment performed with Mariner 10 at the previous solar minimum. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790041801&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790041801&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dwind%2Bmonitor">Signatures of solar wind latitudinal structure in interplanetary Lyman-alpha emissions - Mariner 10 observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kumar, S.; Broadfoot, A. L. 1979-01-01 A detailed analysis is conducted which shows that signatures in the interplanetary Lyman-alpha emissions observed in three different data sets from Mariner 10 (corresponding to different locations of the spacecraft) provide firm evidence that the intensity departures are correlated with a decrease in solar wind flux with increasing latitude. It is suggested that observations of the interplanetary emission can be used to monitor average solar wind activity at high latitudes. The asymmetry in the solar radiation field as a source of observed departures in L-alpha data is considered and attention is given to the interstellar hydrogen and helium density. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DPPN11177L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DPPN11177L">Observations of magnetic pumping in the solar wind using MMS data</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lichko, Emily; Egedal, Jan; Daughton, William; Kasper, Justin 2017-10-01 The turbulent cascade is believed to play an important role in the energization of the solar wind plasma. However, there are characteristics of the solar wind that are not readily explained by the cascade, such as the power-law distribution of the solar wind speed. Starting from the drift kinetic equation, we have derived a magnetic pumping model, similar to the magnetic pumping well-known in fusion research, that provides an explanation for these features. In this model, particles are heated by the largest scale turbulent fluctuations, providing a complementary heating mechanism to the turbulent cascade. We will present observations of this mechanism in the bow shock region using data from the Magnetospheric MultiScale mission. This research was conducted with support from National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168, as well as from NSF Award 1404166 and NASA award NNX15AJ73G. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150010735','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150010735">On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20150010735'); toggleEditAbsImage('author_20150010735_show'); toggleEditAbsImage('author_20150010735_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20150010735_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20150010735_hide"> 2014-01-01 We analyze the Rontgen satellite (ROSAT) position sensitive proportional counter soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges: two 19 deg wedges (one north and one south) 13-32 deg off the terminator toward the dark side and one wedge 38 deg wide centered on the antisolar direction. The radial profiles of both the north and the south wedges show significant limb brightening that is absent in the 38 deg wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears to be dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now, along with Mars, Venus, and Earth, the Moon represents another solar system body at which SWCX has been observed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020010112','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020010112">Properties of Minor Ions in the Solar Wind and Implications for the Background Solar Wind Plasma</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Esser, Ruth; Ling, James (Technical Monitor) 2001-01-01 Ion charge states measured in situ in interplanetary space carry information on the properties of the solar wind plasma in the inner corona where these ion charge states are formed. The goal of the proposed research was to determine solar wind models and coronal observations that are necessary tools for the interpretation of the ion charge state observations made in situ in the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH51D2610K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH51D2610K">Identifying and Characterizing Kinetic Instabilities using Solar Wind Observations of Non-Maxwellian Plasmas</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Klein, K. G. 2016-12-01 Weakly collisional plasmas, of the type typically observed in the solar wind, are commonly in a state other than local thermodynamic equilibrium. This deviation from a Maxwellian velocity distribution can be characterized by pressure anisotropies, disjoint beams streaming at differing speeds, leptokurtic distributions at large energies, and other non-thermal features. As these features may be artifacts of dynamic processes, including the the acceleration and expansion of the solar wind, and as the free energy contained in these features can drive kinetic micro-instabilities, accurate measurement and modeling of these features is essential for characterizing the solar wind. After a review of these features, a technique is presented for the efficient calculation of kinetic instabilities associated with a general, non-Maxwellian plasma. As a proof of principle, this technique is applied to bi-Maxwellian systems for which kinetic instability thresholds are known, focusing on parameter scans including beams and drifting heavy minor ions. The application of this technique to fits of velocity distribution functions from current, forthcoming, and proposed missions including WIND, DSCOVR, Solar Probe Plus, and THOR, as well as the underlying measured distribution functions, is discussed. Particular attention is paid to the effects of instrument pointing and integration time, as well as potential deviation between instabilities associated with the Maxwellian fits and those associated with the observed, potentially non-Maxwellian, velocity distribution. Such application may further illuminate the role instabilities play in the evolution of the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSH33A4124Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSH33A4124Y">How Well Does the S-Web Theory Predict In-Situ Observations of the Slow Solar Wind?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Young, A. K.; Antiochos, S. K.; Linker, J.; Zurbuchen, T. 2014-12-01 The S-Web theory provides a physical explanation for the origin and properties of the slow solar wind, particularly its composition. The theory proposes that magnetic reconnection along topologically complex boundaries between open and closed magnetic fields on the sun releases plasma from closed magnetic field regions into the solar wind at latitudes away from the heliospheric current sheet. Such a wind would have elevated charge states compared to the fast wind and an elemental composition resembling the closed-field corona. This theory is currently being tested using time-dependent, high-resolution, MHD simulations, however comparisons to in-situ observations play an essential role in testing and understanding slow-wind release mechanisms. In order to determine the relationship between S-Web signatures and the observed, slow solar wind, we compare plasma data from the ACE and Ulysses spacecraft to solutions from the steady-state models created at Predictive Science, Inc., which use observed magnetic field distributions on the sun as a lower boundary condition. We discuss the S-Web theory in light of our results and the significance of the S-Web for interpreting current and future solar wind observations. This work was supported, in part, by the NASA TR&T and SR&T programs. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active">3</li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active">4</li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980018649','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980018649">Constraints on Solar Wind Acceleration Mechanisms from Ulysses Plasma Observations: The First Polar Pass</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Barnes, Aaron; Gazis, Paul R.; Phillips, John L. 1995-01-01 The mass flux density and velocity of the solar wind at polar latitudes can provide strong constraints on solar wind acceleration mechanisms. We use plasma observations from the first polar passage of the Ulysses spacecraft to investigate this question. We find that the mass flux density and velocity are too high to reconcile with acceleration of the solar wind by classical thermal conduction alone. Therefore acceleration of the high-speed must involve extended deposition of energy by some other mechanism, either as heat or as a direct effective pressure, due possibly to waves and/or turbulence, or completely non-classical heat transport. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930049687&hterms=energy+regions+Remote&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Denergy%2Bregions%2BRemote','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930049687&hterms=energy+regions+Remote&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Denergy%2Bregions%2BRemote">Remote radio observations of solar wind parameters upstream of planetary bow shocks</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Macdowall, R. J.; Stone, R. G.; Gaffey, J. D., Jr. 1992-01-01 Radio emission is frequently produced at twice the electron plasma frequency 2fp in the foreshock region upstream of the terrestrial bow shock. Observations of this emission provide a remote diagnostic of solar wind parameters in the foreshock. Using ISEE-3 radio data, we present the first evidence that the radio intensity is proportional to the kinetic energy flux and to other parameters correlated with solar wind density. We provide a qualitative explanation of this intensity behavior and predict the detection of similar emission at Jupiter by the Ulysses spacecraft. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018LPICo2047.6110J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018LPICo2047.6110J">Sodium Pick-Up Ion Observations in the Solar Wind Upstream of Mercury</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jasinski, J. M.; Raines, J. M.; Slavin, J. A.; Regoli, L. R.; Murphy, N. 2018-05-01 We present the first observations of sodium pick-up ions upstream of Mercury’s magnetosphere. From these observations we infer properties of Mercury’s sodium exosphere and implications for the solar wind interaction with Mercury’s magnetosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990111616&hterms=1756&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D1756','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990111616&hterms=1756&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D1756">A CME-Driven Solar Wind Disturbance Observed at both Low and High Heliographic Latitudes</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gosling, J. T.; McComas, D. J.; Phillips, J. L.; Pizzo, V. J.; Goldstein, B. E.; Forsyth, R. J.; Lepping, R. P. 1995-01-01 A solar wind disturbance produced by a fast coronal mass ejection, CME, that departed from the Sun on February 20, 1994 was observed in the ecliptic plane at 1 AU by IMP 8 and at high heliographic latitudes at 3.53 AU by Ulysses. In the ecliptic the disturbance included a strong forward shock but no reverse shock, while at high latitudes the disturbance was bounded by a relatively weak forward-reverse shock pair. It is clear that the disturbance in the ecliptic plane was driven primarily by the relative speed between the CME and a slower ambient solar wind ahead, whereas at higher latitudes the disturbance was driven by expansion of the CME. The combined IMP 8 and Ulysses observations thus provide a graphic illustration of how a single fast CME can produce very different types of solar wind disturbances at low and high heliographic latitudes. Simple numerical simulations help explain observed differences at the two spacecraft. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27194962','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27194962">Wave Modeling of the Solar Wind.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Ofman, Leon The acceleration and heating of the solar wind have been studied for decades using satellite observations and models. However, the exact mechanism that leads to solar wind heating and acceleration is poorly understood. In order to improve the understanding of the physical mechanisms that are involved in these processes a combination of modeling and observational analysis is required. Recent models constrained by satellite observations show that wave heating in the low-frequency (MHD), and high-frequency (ion-cyclotron) range may provide the necessary momentum and heat input to coronal plasma and produce the solar wind. This review is focused on the results of several recent solar modeling studies that include waves explicitly in the MHD and the kinetic regime. The current status of the understanding of the solar wind acceleration and heating by waves is reviewed. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040061975&hterms=statistics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dstatistics','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040061975&hterms=statistics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dstatistics">The Genesis Mission Solar Wind Collection: Solar-Wind Statistics over the Period of Collection</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Barraclough, B. L.; Wiens, R. C.; Steinberg, J. E.; Reisenfeld, D. B.; Neugebauer, M.; Burnett, D. S.; Gosling, J.; Bremmer, R. R. 2004-01-01 The NASA Genesis spacecraft was launched August 8, 2001 on a mission to collect samples of solar wind for 2 years and return them to earth September 8, 2004. Detailed analyses of the solar wind ions implanted into high-purity collection substrates will be carried out using various mass spectrometry techniques. These analyses are expected to determine key isotopic ratios and elemental abundances in the solar wind, and by extension, in the solar photosphere. Further, the photospheric composition is thought to be representative of the solar nebula with a few exceptions, so that the Genesis mission will provide a baseline for the average solar nebula composition with which to compare present-day compositions of planets, meteorites, and asteroids. The collection of solar wind samples is almost complete. Collection began for most substrates in early December, 2001, and is scheduled to be complete on April 2 of this year. It is critical to understand the solar-wind conditions during the collection phase of the mission. For this reason, plasma ion and electron spectrometers are continuously monitoring the solar wind proton density, velocity, temperature, the alpha/proton ratio, and angular distribution of suprathermal electrons. Here we report on the solar-wind conditions as observed by these in-situ instruments during the first half of the collection phase of the mission, from December, 2001 to present. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17832984','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17832984">Initial observations of the pioneer venus orbiter solar wind plasma experiment.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Wolfe, J; Intriligator, D S; Mihalov, J; Collard, H; McKibbin, D; Whitten, R; Barnes, A 1979-02-23 Initial results of observations of the solar wind interaction with Venus indicate that Venus has a well-defined, strong, standing bow shock wave. Downstream from the shock, an ionosheath is observed in which the compressed and heated postshock plasma evidently interacts directly with the Venus ionosphere. Plasma ion velocity deflections observed within the ionosheath are consistent with flow around the blunt shape of the ionopause. The ionopause boundary is observed and defined by this experiment as the location where the ionosheath ion flow is first excluded. The positions of the bow shock and ionopause are variable and appear to respond to changes in the external solar wind pressure. Near the terminator the bow shock was observed at altitudes of approximately 4600 to approximately 12,000 kilometers. The ionopause altitutde ranged fromn as low as approximately 450 to approximately 1950 kilometers. Within the Venus ionosphere low-energy ions (energy per untit charge < 30 volts) were detected and have been tentatively idtentified as nonflowing ionospheric ions incident from a direction along the spacecraft velocity vector. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990056504&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990056504&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsolar%2Bintensity%2Bmeasurement">Solar wind acceleration in the solar corona</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Giordano, S.; Antonucci, E.; Benna, C.; Kohl, J. L.; Noci, G.; Michels, J.; Fineschi, S. 1997-01-01 The intensity ratio of the O VI doublet in the extended area is analyzed. The O VI intensity data were obtained with the ultraviolet coronagraph spectrometer (UVCS) during the SOHO campaign 'whole sun month'. The long term observations above the north pole of the sun were used for the polar coronal data. Using these measurements, the solar wind outflow velocity in the extended corona was determined. The 100 km/s level is running along the streamer borders. The acceleration of the solar wind is found to be high in regions between streamers. In the central part of streamers, the outflow velocity of the coronal plasma remains below 100 km/s at least within 3.8 solar radii. The regions at the north and south poles, characterized by a more rapid acceleration of the solar wind, correspond to regions where the UVCS observes enhanced O VI line broadenings. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10856203','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10856203">The solar wind-magnetosphere-ionosphere system</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Lyon 2000-06-16 The solar wind, magnetosphere, and ionosphere form a single system driven by the transfer of energy and momentum from the solar wind to the magnetosphere and ionosphere. Variations in the solar wind can lead to disruptions of space- and ground-based systems caused by enhanced currents flowing into the ionosphere and increased radiation in the near-Earth environment. The coupling between the solar wind and the magnetosphere is mediated and controlled by the magnetic field in the solar wind through the process of magnetic reconnection. Understanding of the global behavior of this system has improved markedly in the recent past from coordinated observations with a constellation of satellite and ground instruments. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810044425&hterms=radiation+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dradiation%2BSolar','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810044425&hterms=radiation+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dradiation%2BSolar">Polar solar wind and interstellar wind properties from interplanetary Lyman-alpha radiation measurements</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Witt, N.; Blum, P. W.; Ajello, J. M. 1981-01-01 The analysis of Mariner 10 observations of Lyman-alpha resonance radiation shows an increase of interplanetary neutral hydrogen densities above the solar poles. This increase is caused by a latitudinal variation of the solar wind velocity and/or flux. Using both the Mariner 10 results and other solar wind observations, the values of the solar wind flux and velocity with latitude are determined for several cases of interest. The latitudinal variation of interplanetary hydrogen gas, arising from the solar wind latitudinal variation, is shown to be most pronounced in the inner solar system. From this result it is shown that spacecraft Lyman-alpha observations are more sensitive to the latitudinal anisotropy for a spacecraft location in the inner solar system near the downwind axis. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.2574D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.2574D">Solar Wind Deflection by Mass Loading in the Martian Magnetosheath Based on MAVEN Observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dubinin, E.; Fraenz, M.; Pätzold, M.; Halekas, J. S.; Mcfadden, J.; Connerney, J. E. P.; Jakosky, B. M.; Vaisberg, O.; Zelenyi, L. 2018-03-01 Mars Atmosphere and Volatile EvolutioN observations at Mars show clear signatures of the shocked solar wind interaction with the extended oxygen atmosphere and hot corona displayed in a lateral deflection of the magnetosheath flow in the direction opposite to the direction of the solar wind motional electric field. The value of the velocity deflection reaches ˜50 km/s. The occurrence of such deflection is caused by the "Lorentz-type" force due to a differential streaming of the solar wind protons and oxygen ions originating from the extended oxygen corona. The value of the total deceleration of the magnetosheath flow due to mass loading is estimated as ˜40 km/s. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814547D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814547D">Improvement of background solar wind predictions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dálya, Zsuzsanna; Opitz, Andrea 2016-04-01 In order to estimate the solar wind properties at any heliospheric positions propagation tools use solar measurements as input data. The ballistic method extrapolates in-situ solar wind observations to the target position. This works well for undisturbed solar wind, while solar wind disturbances such as Corotating Interaction Regions (CIRs) and Coronal Mass Ejections (CMEs) need more consideration. We are working on dedicated ICME lists to clean these signatures from the input data in order to improve our prediction accuracy. These ICME lists are created from several heliospheric spacecraft measurements: ACE, WIND, STEREO, SOHO, MEX and VEX. As a result, we are able to filter out these events from the time series. Our corrected predictions contribute to the investigation of the quiet solar wind and space weather studies. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020044001','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020044001">Properties of Minor Ions In the Solar Wind and Implications for the Background Solar Wind Plasma</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Esser, Ruth; Wagner, William (Technical Monitor) 2002-01-01 Ion charge states measured in situ in interplanetary space carry information on the properties of the solar wind plasma in the inner corona. The goal of the proposal is to determine coronal plasma conditions that produce the in situ observed charge states. This study is carried out using solar wind models, coronal observations, ion fraction calculations and in situ observations. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770027726&hterms=Krieger&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DKrieger','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770027726&hterms=Krieger&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DKrieger">Coronal holes as sources of solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Nolte, J. T.; Krieger, A. S.; Timothy, A. F.; Gold, R. E.; Roelof, E. C.; Vaiana, G.; Lazarus, A. J.; Sullivan, J. D.; Mcintosh, P. S. 1976-01-01 We investigate the association of high-speed solar wind with coronal holes during the Skylab mission by: (1) direct comparison of solar wind and coronal X-ray data; (2) comparison of near-equatorial coronal hole area with maximum solar wind velocity in the associated streams; and (3) examination of the correlation between solar and interplanetary magnetic polarities. We find that all large near-equatorial coronal holes seen during the Skylab period were associated with high-velocity solar wind streams observed at 1 AU. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH53A..05D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH53A..05D">Imaging the Top of the Solar Corona and the Young Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> DeForest, C. E.; Matthaeus, W. H.; Viall, N. M.; Cranmer, S. R. 2016-12-01 We present the first direct visual evidence of the quasi-stationary breakup of solar coronal structure and the rise of turbulence in the young solar wind, directly in the future flight path of Solar Probe. Although the corona and, more recently, the solar wind have both been observed directly with Thomson scattered light, the transition from the corona to the solar wind has remained a mystery. The corona itself is highly structured by the magnetic field and the outflowing solar wind, giving rise to radial "striae" - which comprise the familiar streamers, pseudostreamers, and rays. These striae are not visible in wide-field heliospheric images, nor are they clearly delineated with in-situ measurements of the solar wind. Using careful photometric analysis of the images from STEREO/HI-1, we have, for the first time, directly observed the breakup of radial coronal structure and the rise of nearly-isotropic turbulent structure in the outflowing slow solar wind plasma between 10° (40 Rs) and 20° (80 Rs) from the Sun. These observations are important not only for their direct science value, but for predicting and understanding the conditions expected near SPP as it flies through - and beyond - this final frontier of the heliosphere, the outer limits of the solar corona. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820036544&hterms=coulomb+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcoulomb%2Blaw','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820036544&hterms=coulomb+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcoulomb%2Blaw">Solar wind helium ions - Observations of the Helios solar probes between 0.3 and 1 AU</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Marsch, E.; Rosenbauer, H.; Schwenn, R.; Muehlhaeuser, K.-H.; Neubauer, F. M. 1982-01-01 A Helios solar probe survey of solar wind helium ion velocity distributions and derived parameters between 0.3 and 1 AU is presented. Distributions in high-speed wind are found to generally have small total anisotropies, with some indication that, in the core part, the temperatures are greater parallel rather than perpendicular to the magnetic field. The anisotropy tends to increase with heliocentric radial distance, and the average dependence of helium ion temperatures on radial distance from the sun is described by a power law. Differential ion speeds with values of more than 150 km/sec are observed near perihelion, or 0.3 AU. The role of Coulomb collisions in limiting differential ion speeds and the ion temperature ratio is investigated, and it is found that collisions play a distinct role in low-speed wind, by limiting both differential ion velocity and temperature. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010046973&hterms=kellogg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dkellogg','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010046973&hterms=kellogg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dkellogg">Ion Isotropy and Ion Resonant Waves in the Solar Wind: Cassini Observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kellogg, Paul J.; Gurnett, Donald A.; Hospodarsky, George B.; Kurth, William S. 2001-01-01 Electric fields in the solar wind, in the range of one Hertz, are reported for the first time from a 3-axis stabilized spacecraft. The measurements are made with the Radio and Plasma Wave System (RPWS) experiment on the Cassini spacecraft. Kellogg suggested that such waves could be important in maintaining the near-isotropy of solar wind ions and the validity of MHD for the description of the solar wind. The amplitudes found are larger than those estimated by Kellogg from other measurements, and are due to quasi-electrostatic waves. These amplitudes are quite sufficient to maintain isotropy of the solar wind ions. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH54A..06H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH54A..06H">Solar wind classification from a machine learning perspective</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Heidrich-Meisner, V.; Wimmer-Schweingruber, R. F. 2017-12-01 It is a very well known fact that the ubiquitous solar wind comes in at least two varieties, the slow solar wind and the coronal hole wind. The simplified view of two solar wind types has been frequently challenged. Existing solar wind categorization schemes rely mainly on different combinations of the solar wind proton speed, the O and C charge state ratios, the Alfvén speed, the expected proton temperature and the specific proton entropy. In available solar wind classification schemes, solar wind from stream interaction regimes is often considered either as coronal hole wind or slow solar wind, although their plasma properties are different compared to "pure" coronal hole or slow solar wind. As shown in Neugebauer et al. (2016), even if only two solar wind types are assumed, available solar wind categorization schemes differ considerably for intermediate solar wind speeds. Thus, the decision boundary between the coronal hole and the slow solar wind is so far not well defined.In this situation, a machine learning approach to solar wind classification can provide an additional perspective.We apply a well-known machine learning method, k-means, to the task of solar wind classification in order to answer the following questions: (1) How many solar wind types can reliably be identified in our data set comprised of ten years of solar wind observations from the Advanced Composition Explorer (ACE)? (2) Which combinations of solar wind parameters are particularly useful for solar wind classification?Potential subtypes of slow solar wind are of particular interest because they can provide hints of respective different source regions or release mechanisms of slow solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.P13A1901L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.P13A1901L">Solar Wind Interaction and Crustal Field Influences on Mars' Upper Ionosphere: MAVEN Observations Compared to Model Results</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Luhmann, J. G.; Alvarez, K.; Curry, S.; Dong, C.; Ma, Y.; Bougher, S. W.; Benna, M.; Elrod, M. K.; Mahaffy, P. R.; Withers, P.; Girazian, Z.; Connerney, J. E. P.; Brain, D.; Jakosky, B. M. 2016-12-01 Since the two Viking Landers, progress on improving our global knowledge of the Martian ionosphere's characteristics has been limited by the available instrumentation and sampling geometries. In particular, while remote sensing and the lower energy plasma spectrometer observations on missions including MGS and MEX provided insights on the effects of the crustal magnetic fields of Mars and the solar wind interaction, these measurements did not allow the broader thermal ion surveys necessary to test our current understanding of the region between the exobase at 200 km altitude and the solar wind interaction boundary. In this study we use the MAVEN NGIMS thermal ion mass spectrometer observations from the prime mission year 2015 to construct some statistical pictures of the increasingly collisionless region of the ionosphere between 200 and 500 km where crustal field and solar wind interaction effects should begin to dominate its behavior. Comparisons with models of the solar wind interaction with Mars provide important global context for these observations, including the roles of system diversity associated with changing crustal field and interplanetary field orientations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1720b0006Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1720b0006Z">Anomalously low C6+/C5+ ratio in solar wind: ACE/SWICS observation</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhao, L.; Landi, E.; Kocher, M.; Lepri, S. T.; Fisk, L. A.; Zurbuchen, T. H. 2016-03-01 The Carbon and Oxygen ionization states in the solar wind plasma freeze-in within 2 solar radii (Rs) from the solar surface, and then they do not change as they propagate with the solar wind into the heliosphere. Therefore, the O7+/O6+ and C6+/C5+ charge state ratios measured in situ maintain a record of the thermal properties (electron temperature and density) of the inner corona where the solar wind originates. Since these two ratios freeze-in at very similar height, they are expected to be correlated. However, an investigation of the correlation between these two ratios as measured by ACE/SWICS instrument from 1998 to 201l shows that there is a subset of "Outliers" departing from the expected correlation. We find about 49.4% of these Outliers is related to the Interplanetary Coronal Mass Ejections (ICMEs), while 49.6% of them is slow speed wind (Vp < 500 km/s) and about 1.0% of them is fast solar wind (Vp > 500 km/s). We compare the outlier-slow-speed wind with the normal slow wind (defined as Vp < 500 km/s and O7+/O6+ > 0.2) and find that the reason that causes the Outliers to depart from the correlation is their extremely depleted C6+/C5+ ratio which is decreased by 80% compared to the normal slow wind. We discuss the implication of the Outlier solar wind for the solar wind acceleration mechanism. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active">4</li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active">5</li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810038514&hterms=1587&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231587','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810038514&hterms=1587&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231587">Latitude dependence of solar wind velocity observed at not less than 1 AU</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Mitchell, D. G.; Roelof, E. C.; Wolfe, J. H. 1981-01-01 The large-scale solar wind velocity structure in the outer heliosphere has been systematically analyzed for Carrington rotations 1587-1541 (March 1972 to April 1976). Spacecraft data were taken from Imp 7/8 at earth, Pioneer 6, 8, and 9 near 1 AU, and Pioneer 10 and 11 between 1.6 and 5 AU. Using the constant radial velocity solar wind approximation to map all of the velocity data to its high coronal emission heliolongitude, the velocity structure observed at different spacecraft was examined for latitudinal dependence and compared with coronal structure in soft X-rays and H-alpha absorption features. The constant radial velocity approximation usually remains self-consistent in decreasing or constant velocity solar wind out to 5 AU, enabling us to separate radial from latitudinal propagation effects. Several examples of sharp nonmeridional stream boundaries in interplanetary space (about 5 deg latitude in width), often directly associated with features in coronal X-rays and H-alpha were found. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040074203','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040074203">Properties of Minor Ions in the Solar Wind and Implications for the Background Solar Wind Plasma</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Wagner, William (Technical Monitor); Esser, Ruth 2004-01-01 The scope of the investigation is to extract information on the properties of the bulk solar wind from the minor ion observations that are provided by instruments on board NASA space craft and theoretical model studies. Ion charge states measured in situ in interplanetary space are formed in the inner coronal regions below 5 solar radii, hence they carry information on the properties of the solar wind plasma in that region. The plasma parameters that are important in the ion forming processes are the electron density, the electron temperature and the flow speeds of the individual ion species. In addition, if the electron distribution function deviates from a Maxwellian already in the inner corona, then the enhanced tail of that distribution function, also called halo, greatly effects the ion composition. This study is carried out using solar wind models, coronal observations, and ion calculations in conjunction with the in situ observations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGRA..112.8104O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRA..112.8104O">Solar wind structure suggested by bimodal correlations of solar wind speed and density between the spacecraft SOHO and Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ogilvie, K. W.; Coplan, M. A.; Roberts, D. A.; Ipavich, F. 2007-08-01 We calculate the cross-spacecraft maximum lagged-cross-correlation coefficients for 2-hour intervals of solar wind speed and density measurements made by the plasma instruments on the Solar and Heliospheric Observatory (SOHO) and Wind spacecraft over the period from 1996, the minimum of solar cycle 23, through the end of 2005. During this period, SOHO was located at L1, about 200 R E upstream from the Earth, while Wind spent most of the time in the interplanetary medium at distances of more than 100 R E from the Earth. Yearly histograms of the maximum, time-lagged correlation coefficients for both the speed and density are bimodal in shape, suggesting the existence of two distinct solar wind regimes. The larger correlation coefficients we suggest are due to structured solar wind, including discontinuities and shocks, while the smaller are likely due to Alfvénic turbulence. While further work will be required to firmly establish the physical nature of the two populations, the results of the analysis are consistent with a solar wind that consists of turbulence from quiet regions of the Sun interspersed with highly filamentary structures largely convected from regions in the inner solar corona. The bimodal appearance of the distributions is less evident in the solar wind speed than in the density correlations, consistent with the observation that the filamentary structures are convected with nearly constant speed by the time they reach 1 AU. We also find that at solar minimum the fits for the density correlations have smaller high-correlation components than at solar maximum. We interpret this as due to the presence of more relatively uniform Alfvénic regions at solar minimum than at solar maximum. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030020816&hterms=background+wind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbackground%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030020816&hterms=background+wind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbackground%2Bwind">Properties of Minor Ions in the Solar Wind and Implications for the Background Solar Wind Plasma</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Esser, Ruth; Wagner, William (Technical Monitor) 2003-01-01 Ion charge states measured in situ in interplanetary space are formed in the inner coronal regions below 5 solar radii, hence they carry information on the properties of the solar wind plasma in that region. The plasma parameters that are important in the ion forming processes are the electron density, the electron temperature and the flow speeds of the individual ion species. In addition, if the electron distribution function deviates from a Maxwellian already in the inner corona, then the enhanced tail of that distribution function, also called halo, greatly effects the ion composition. The goal of the proposal is to make use of ion fractions observed in situ in the solar wind to learn about both, the plasma conditions in the inner corona and the expansion and ion formation itself. This study is carried out using solar wind models, coronal observations, and ion fraction calculations in conjunction with the in situ observations. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021300&hterms=dimensions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddimensions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021300&hterms=dimensions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddimensions">The solar wind in the third dimension</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Neugebauer, M. 1995-01-01 For many years, solar-wind physicists have been using plasma and field data acquired near the ecliptic plane together with data on the scintillation of radio sources and remote sensing of structures in the solar corona to estimate the properties of the high-latitude solar wind, Because of the highly successful Ulysses mission, the moment of truth is now here. This talk summarizes the principal differences between the high and low latitude solar winds at the declining phase of the solar-activity cycle and between the Ulysses observations and expectations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014FrASS...1....4E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014FrASS...1....4E">A survey of solar wind conditions at 5 AU: A tool for interpreting solar wind-magnetosphere interactions at Jupiter</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ebert, Robert; Bagenal, Fran; McComas, David; Fowler, Christopher 2014-09-01 We examine Ulysses solar wind and interplanetary magnetic field (IMF) observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1 - 4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013), Jupiter’s bow shock and magnetopause is expected to be at least 8 - 12% further from Jupiter, if these trends continue. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870067070&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorbiting%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870067070&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorbiting%2Bwind">Simultaneous observation of Pc 3-4 pulsations in the solar wind and in the earth's magnetosphere</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Engebretson, M. J.; Zanetti, L. J.; Potemra, T. A.; Baumjohann, W.; Luehr, H.; Acuna, M. H. 1987-01-01 The equatorially orbiting Active Magnetospheric Particle Tracer Explorers CCE and IRM satellites have made numerous observations of Pc 3-4 magnetic field pulsations (10-s to 100-s period) simultaneously at locations upstream of the earth's bow shock and inside the magnetosphere. These observations show solar wind/IMF control of two categories of dayside magnetospheric pulsations. Harmonically structured, azimuthally polarized pulsations are commonly observed from L = 4 to 9 in association with upstream waves. More monochromatic compressional pulsations are clearly evident on occasion, with periods identical to those observed simultaneously in the solar wind. The observations reported here are consistent with a high-latitude (cusp) entry mechanism for wave energy related to harmonically structured pulsations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940030719','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940030719">Flank solar wind interaction</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Moses, Stewart L.; Greenstadt, Eugene W.; Coroniti, Ferdinand V. 1994-01-01 In this report we will summarize the results of the work performed under the 'Flank Solar Wind Interaction' investigation in support of NASA's Space Physics Guest Investigator Program. While this investigation was focused on the interaction of the Earth's magnetosphere with the solar wind as observed by instruments on the International Sun-Earth Explorer (ISEE) 3 spacecraft, it also represents the culmination of decades of research performed by scientists at TRW on the rich phenomenology of collisionless shocks in space. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SoPh..291.3777L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SoPh..291.3777L">A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 - 24 Minimum</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Liou, Kan; Wu, Chin-Chun 2016-12-01 Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23 - 24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth's orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind region (SWR) can have a direct influence on the solar wind parameters near the Earth. In this study, we analyze solar wind plasma and magnetic field data of hourly values acquired by Ulysses. It is found that the solar wind, when averaging over the first (1995.6 - 1995.8) and third (2006.9 - 2008.2) Ulysses' perihelion ({˜} 1.4 AU) crossings, was about the same speed, but significantly less dense ({˜} 34 %) and cooler ({˜} 20 %), and the total magnetic field was {˜} 30 % weaker during the third compared to the first crossing. It is also found that the SWR was {˜} 50 % wider in the third ({˜} 68.5^deg; in heliographic latitude) than in the first ({˜} 44.8°) solar orbit. The observed latitudinal increase in the SWR is sufficient to explain the excessive decline in the near-Earth solar wind density during the recent solar minimum without speculating that the total solar output may have been decreasing. The observed SWR inflation is also consistent with a cooler solar wind in the SC-23/24 than in the SC-22/23 minimum. Furthermore, the ratio of the high-to-low latitude photospheric magnetic field (or equatorward magnetic pressure force), as observed by the Mountain Wilson Observatory, is smaller during the third than the first Ulysses' perihelion orbit. These findings suggest that the smaller equatorward magnetic pressure at the Sun may have led to the latitudinally-wider SRW observed by Ulysses in SC-23/24 minimum. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH51D2606P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH51D2606P">Kinetic Features Observed in the Solar Wind Electron Distributions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pierrard, V.; Lazar, M.; Poedts, S. 2016-12-01 More than 120 000 of velocity distributions measured by Helios, Cluster and Ulysses in the ecliptic have been analyzed within an extended range of heliocentric distances from 0.3 to over 4 AU. The velocity distribution of electrons reveal a dual structure with a thermal (Maxwellian) core and a suprathermal (Kappa) halo. A detailed observational analysis of these two components provides estimations of their temperatures and temperature anisotropies, and we decode any potential interdependence that their properties may indicate. The core temperature is found to decrease with the radial distance, while the halo temperature slightly increases, clarifying an apparent contradiction in previous observational analysis and providing valuable clues about the temperature of the Kappa-distributed populations. For low values of the power-index kappa, these two components manifest a clear tendency to deviate from isotropy in the same direction, that seems to confirm the existence of mechanisms with similar effects on both components, e.g., the solar wind expansion, or the particle heating by the fluctuations. However, the existence of plasma states with anti-correlated anisotropies of the core and halo populations and the increase of their number for high values of the power-index kappa suggest a dynamic interplay of these components, mediated most probably by the anisotropy-driven instabilities. Estimating the temperature of the solar wind particles and their anisotropies is particularly important for understanding the origin of these deviations from thermal equilibrium as well as their effects. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021493&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D30%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021493&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D30%26Ntt%3Dlazarus">Catalog of solar wind events identified from observations by ISTP spacecraft</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Peredo, M.; Berdichevsky, D.; Byrnes, J.; Lepping, R. P.; Ogilvie, K.; Lazarus, A. J.; Paularena, K. I.; Steinberg, J. T. 1995-01-01 The ISTP Science Planning and Operations Facility (SPOF), in collaboration with ISTP investigators, is developing a catalog of solar wind events and features. The catalog is primarily based on plasma and magnetic field observations from the WIND and IMP-8 spacecraft. Interplanetary events that may trigger magnetospheric activity are included as well as features of interest for using the solar wind as a plasma laboratory. Catalog coverage begins on September 8, 1992, the start of ISTP science data collection. The catalog is based on Key Parameter data sets (preliminary summary data at approximately 1 min time resolution produced quickly for survey purposes) and as such has limited citability in formal scientific work. Its primary intent is to serve as a reference for identifying candidate periods for further study, such as may be the focus of coordinated data analysis efforts during ISTP and/or IACG Science Campaigns. To facilitate access by members of the ISTP and wider space physics communities, the catalog will be available on the World Wide Web. The contents of the catalog will be described, and samples of catalog information will be presented. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760059724&hterms=rickets&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Drickets','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760059724&hterms=rickets&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Drickets">High-latitude observations of solar wind streams and coronal holes</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ricket, B. J.; Sime, D. G.; Crockett, W. R.; Tousey, R.; Sheeley, N. R., Jr. 1976-01-01 Interplanetary scintillation observations of the solar wind velocity during 1973 and the first part of 1974 reveal several corotating high-speed streams. These streams, of heliographic latitudes from +40 deg to -60 deg, have been mapped back to the vicinity of the sun and have been compared with coronal holes identified in wide band XUV solar images taken during the manned portions of the Skylab mission. There is some evidence that the high-speed streams are preferentially associated with coronal holes and that they can spread out from the hole boundaries up to about 20 deg in latitude. However, this association is not one to one; streams are observed which do not map back to coronal holes, and holes are observed which do not lie at the base of streams. To the extent that a statistical interpretation is possible the association is not highly significant, but individual consideration of streams and holes suggests that the statistical result is biased somewhat against a strong correlation. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720020181','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720020181">Solar wind physics</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 1972-01-01 A double-chambered gas proportional counter was constructed to detect and identify solar wind ions after acceleration by a high voltage power supply. It was determined that the best method of detecting deuterium in the solar wind is to use a tritium target as proposed for IMP H and J. The feasibility of detecting H(+) and He(+) ions of interstellar origin is considered. A program is described to carry out ground-based astronomical observations of faint, diffuse optical emission lines from interstellar gas. Hydrogen and oxygen emission lines from galactic sources were detected and the galactic and geocoronal H alpha and beta lines were clearly resolved. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017nova.pres.2278K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017nova.pres.2278K">Escape for the Slow Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kohler, Susanna 2017-05-01 Plasma from the Sun known as the slow solar wind has been observed far away from where scientists thought it was produced. Now new simulations may have resolved the puzzle of where the slow solar wind comes from and how it escapes the Sun to travel through our solar system.An Origin PuzzleA full view of a coronal hole (dark portion) from SDO. The edges of the coronal hole mark the boundary between open and closed magnetic field lines. [SDO; adapted from Higginson et al. 2017]The Suns atmosphere, known as the corona, is divided into two types of regions based on the behavior of magnetic field lines. In closed-field regions, the magnetic field is firmly anchored in the photosphere at both ends of field lines, so traveling plasma is confined to coronal loops and must return to the Suns surface. In open-field regions, only one end of each magnetic field line is anchored in the photosphere, so plasma is able to stream from the Suns surface out into the solar system.This second type of region known as a coronal hole is thought to be the origin of fast-moving plasma measured in our solar system and known as the fast solar wind. But we also observe a slow solar wind: plasma that moves at speeds of less than 500 km/s.The slow solar wind presents a conundrum. Its observational properties strongly suggest it originates in the hot, closed corona rather than the cooler, open regions. But if the slow solar wind plasma originates in closed-field regions of the Suns atmosphere, then how does it escape from the Sun?Slow Wind from Closed FieldsA team of scientists led by Aleida Higginson (University of Michigan) has now used high-resolution, three-dimensional magnetohydrodynamic simulations to show how the slow solar wind can be generated from plasma that starts outin closed-field parts of the Sun.A simulated heliospheric arc, composed of open magnetic field lines. [Higginson et al. 2017]Motions on the Suns surface near the boundary between open and closed-field regions the boundary </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860014074','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860014074">Solar wind-magnetosphere coupling and the distant magnetotail: ISEE-3 observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Slavin, J. A.; Smith, E. J.; Sibeck, D. G.; Baker, D. N.; Zwickl, R. D.; Akasofu, S. I.; Lepping, R. P. 1985-01-01 ISEE-3 Geotail observations are used to investigate the relationship between the interplanetary magnetic field, substorm activity, and the distant magnetotail. Magnetic field and plasma observations are used to present evidence for the existence of a quasi-permanent, curved reconnection neutral line in the distant tail. The distance to the neutral line varies from absolute value of X = 120 to 140 R/sub e near the center of the tail to beyond absolute value of X = 200 R/sub e at the flanks. Downstream of the neutral line the plasma sheet magnetic field is shown to be negative and directly proportional to negative B/sub z in the solar wind as observed by IMP-8. V/sub x in the distant plasma sheet is also found to be proportional to IMF B/sub z with southward IMF producing the highest anti-solar flow velocities. A global dayside reconnection efficiency of 20 +- 5% is derived from the ISEE-3/IMP-8 magnetic field comparisons. Substorm activity, as measured by the AL index, produces enhanced negative B/sub z and tailward V/sub x in the distant plasma sheet in agreement with the basic predictions of the reconnection-based models of substorms. The rate of magnetic flux transfer out of the tail as a function of AL is found to be consistent with previous near-Earth studies. Similarly, the mass and energy fluxes carried by plasma sheet flow down the tail are consistent with theoretical mass and energy budgets for an open magnetosphere. In summary, the ISEE-3 Geotail observations appear to provide good support for reconnection models of solar wind-magnetosphere coupling and substorm energy rates. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800060994&hterms=thermal+noise&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dthermal%2Bnoise','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800060994&hterms=thermal+noise&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dthermal%2Bnoise">The low-frequency continuum as observed in the solar wind from ISEE 3 - Thermal electrostatic noise</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hoang, S.; Steinberg, J.-L.; Epstein, G.; Tilloles, P.; Fainberg, J.; Stone, R. G. 1980-01-01 The low frequency continuum (LFC) noise between 30 and 200 kHz has been investigated from the ISEE 3 spacecraft in the solar wind by means of a radio astronomy experiment more sensitive than previously available. It is demonstrated that the LFC radiation observed in the solar wind is in the form of longitudinal plasma waves rather than transverse electromagnetic waves. The observed spectral characteristics are found to be a function of antenna length. In addition, both the absence of antenna spin modulation and the fact that these plasma waves do not propagate to large distances imply a local origin for the LFC. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvE..89e2812M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvE..89e2812M">Stationarity of extreme bursts in the solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Moloney, N. R.; Davidsen, J. 2014-05-01 Recent results have suggested that the statistics of bursts in the solar wind vary with solar cycle. Here, we show that this variation is basically absent if one considers extreme bursts. These are defined as threshold-exceeding events over the range of high thresholds for which their number decays as a power law. In particular, we find that the distribution of duration times and energies of extreme bursts in the solar wind ɛ parameter and similar observables are independent of the solar cycle and in this sense stationary, and show robust asymptotic power laws with exponents that are independent of the specific threshold. This is consistent with what has been observed for solar flares and, thus, provides evidence in favor of a link between solar flares and extreme bursts in the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1326029-time-dependent-mhd-simulations-solar-wind-outflow-using-interplanetary-scintillation-observations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1326029-time-dependent-mhd-simulations-solar-wind-outflow-using-interplanetary-scintillation-observations">Time-dependent MHD simulations of the solar wind outflow using interplanetary scintillation observations</a> <a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a> Kim, Tae K.; Pogorelov, Nikolai V.; Borovikov, Sergey N.; ... 2012-11-20 Numerical modeling of the heliosphere is a critical component of space weather forecasting. The accuracy of heliospheric models can be improved by using realistic boundary conditions and confirming the results with in situ spacecraft measurements. To accurately reproduce the solar wind (SW) plasma flow near Earth, we need realistic, time-dependent boundary conditions at a fixed distance from the Sun. We may prepare such boundary conditions using SW speed and density determined from interplanetary scintillation (IPS) observations, magnetic field derived from photospheric magnetograms, and temperature estimated from its correlation with SW speed. In conclusion, we present here the time-dependent MHD simulationmore » results obtained by using the 2011 IPS data from the Solar-Terrestrial Environment Laboratory as time-varying inner boundary conditions and compare the simulated data at Earth with OMNI data (spacecraft-interspersed, near-Earth solar wind data).« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900061749&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dbackground%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900061749&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dbackground%2Bwind">Plasma observations of the solar wind interaction with Mars</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Vaisberg, O. L.; Luhmann, J. G.; Russell, C. T. 1990-01-01 Measurements with the plasma analyzers on the Mars-2, 3 and 5 spacecraft show that Mars deflects a large fraction of the incoming solar wind flow to form a strong bow shock. The bow shock is about 1.41 Rm from the center of the planet at the subsolar point and about 2.40 Rm at the terminator. These distances are similar to those for Venus at times of moderate solar activity. The inferred effective obstacle altitude is about 400-700 km. An ion cushion has been found which is similar in its properties to the Venus magnetic barrier. The formation of this cushion appears to cause the deflection of the solar wind. Inside the cushion but well above the ionosphere is found a region where the ions are at the background, the electrons are cool and the magnetic pressure dominates. This region may resemble a planetary magnetosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...856...53P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...856...53P">The Solar Wind Environment in Time</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pognan, Quentin; Garraffo, Cecilia; Cohen, Ofer; Drake, Jeremy J. 2018-03-01 We use magnetograms of eight solar analogs of ages 30 Myr–3.6 Gyr obtained from Zeeman Doppler Imaging and taken from the literature, together with two solar magnetograms, to drive magnetohydrodynamical wind simulations and construct an evolutionary scenario of the solar wind environment and its angular momentum loss rate. With observed magnetograms of the radial field strength as the only variant in the wind model, we find that a power-law model fitted to the derived angular momentum loss rate against time, t, results in a spin-down relation Ω ∝ t ‑0.51, for angular speed Ω, which is remarkably consistent with the well-established Skumanich law Ω ∝ t ‑0.5. We use the model wind conditions to estimate the magnetospheric standoff distances for an Earth-like test planet situated at 1 au for each of the stellar cases, and to obtain trends of minimum and maximum wind ram pressure and average ram pressure in the solar system through time. The wind ram pressure declines with time as \\overline{{P}ram}}\\propto {t}2/3, amounting to a factor of 50 or so over the present lifetime of the solar system. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active">5</li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active">6</li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6289088-solar-cycle-evolution-solar-wind-speed-structure-between-observed-interplanetary-scintillation-method','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6289088-solar-cycle-evolution-solar-wind-speed-structure-between-observed-interplanetary-scintillation-method">Solar cycle evolution of solar wind speed structure between 1973 and 1985 observed with the interplanetary scintillation method</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kojima, M.; Kakinuma, T. 1987-07-01 The solar cycle evolution of solar wind speed structure was studied for the years from 1973 to 1985 on a basis of interplanetary scintillation observations using a new method for mapping solar wind speed to the source surface. The major minimum-speed regions are distributed along a neutral line through the whole period of a solar cycle: when solar activity is low, they are distributed on the wavy neutral line along the solar equator; in the active phase they also tend to be distributed along the neutral line, which has a large latitudinal amplitude. The minimum-speed regions tend to be distributedmore » not only along the neutral line but also at low magnetic intensity regions and/or coronal bright regions which do not correspond to the neutral line. As the polar high-speed regions extend equatorward around the minimum phase, the latitudinal gradient of speed increases at the boundaries of the low-speed region, and the width of the low-speed region decreases. One or two years before the minimum of solar activity, two localized minimum-speed regions appear on the neutral line, and their locations are longitudinally separated by 180. copyright American Geophysical Union 1987« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080043891&hterms=luck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dluck','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080043891&hterms=luck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dluck">Solar Wind Change Exchange from the Magnetosheath</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Snowden, Steve 2008-01-01 We report the results of a long (approximately 100 ks) XMM-Newton observation designed to observe solar wind charge exchange emission (SWCX) from Earth's magnetosheath. By luck, the observation took place during a period of minimal solar wind flux so the SWCX emission was also minimal. Never-the-less, there is a significant if not stunning correlation between the observed O VIII count rate and our model for magnetosheath emission. We also report on the observed O VII and O VII emission. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1326077-modeling-solar-wind-boundary-conditions-from-interplanetary-scintillations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1326077-modeling-solar-wind-boundary-conditions-from-interplanetary-scintillations">Modeling solar wind with boundary conditions from interplanetary scintillations</a> <a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a> Manoharan, P.; Kim, T.; Pogorelov, N. V.; ... 2015-09-30 Interplanetary scintillations make it possible to create three-dimensional, time- dependent distributions of the solar wind velocity. Combined with the magnetic field observations in the solar photosphere, they help perform solar wind simulations in a genuinely time-dependent way. Interplanetary scintillation measurements from the Ooty Radio Astronomical Observatory in India provide directions to multiple stars and may assure better resolution of transient processes in the solar wind. In this paper, we present velocity distributions derived from Ooty observations and compare them with those obtained with the Wang-Sheeley-Arge (WSA) model. We also present our simulations of the solar wind flow from 0.1 AUmore » to 1 AU with the boundary conditions based on both Ooty and WSA data.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000110132&hterms=May+9th&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMay%2B9th','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000110132&hterms=May+9th&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMay%2B9th">Electrons In The Low Density Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ogilvie, Keith W.; Desch, Michael; Fitzenreiter, Richard; Vondrak, Richard R. (Technical Monitor) 2000-01-01 The recent occurrence of an interval (May 9th to May 12th, 1999) of abnormally low density solar wind has drawn attention to such events. The SWE instrument on the Wind spacecraft observed nine similar events between launch (November 1994) and August 1999: one in 1997, three in 1998, and five in January-August 1999. No such events were observed in 1996, the year of solar minimum. This already suggests a strong dependence upon solar activity. In this paper we discuss observations of the electron strahl, a strong anisotropy in the solar wind electrons above 60 eV directed along the magnetic field and observed continuously during the periods of low density in 1998 and 1999. When the solar wind density was less than 2/cc, the angular width of the strahl was below 3.5 degrees and the temperature deduced from the slope of the electron strahl phase density (as a function of energy in the energy range 200 to 800 eV) was 100 to 150 eV, equivalent to a typical coronal electron temperature. Three examples of this phenomenon, observed on Feb. 20- 22, April 26-27 and May 9-12, 1999, are discussed to show their similarity to one another. These electron observations are interpreted to show that the strahl occurs as a result of the conservation of the first adiabatic invariant, combined with the lack of coulomb collisions as suggested by Fairfield and Scudder, 1985. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22518771-photoionization-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22518771-photoionization-solar-wind">PHOTOIONIZATION IN THE SOLAR WIND</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Landi, E.; Lepri, S. T., E-mail: elandi@umich.edu 2015-10-20 In this work we investigate the effects of photoionization on the charge state composition of the solar wind. Using measured solar EUV and X-ray irradiance, the Michigan Ionization Code and a model for the fast and slow solar wind, we calculate the evolution of the charge state distribution of He, C, N, O, Ne, Mg, Si, S, and Fe with and without including photoionization for both types of wind. We find that the solar radiation has significant effects on the charge state distribution of C, N, and O, causing the ionization levels of these elements to be higher than withoutmore » photoionization; differences are largest for oxygen. The ions commonly observed for elements heavier than O are much less affected, except in ICMEs where Fe ions more ionized than 16+ can also be affected by the solar radiation. We also show that the commonly used O{sup 7+}/O{sup 6+} density ratio is the most sensitive to photoionization; this sensitivity also causes the value of this ratio to depend on the phase of the solar cycle. We show that the O{sup 7+}/O{sup 6+} ratio needs to be used with caution for solar wind classification and coronal temperature estimates, and recommend the C{sup 6+}/C{sup 4+} ratio for these purposes.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890006481','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890006481">Solar wind observations with the ion composition instrument aboard the ISEE-3 ICE spacecraft</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ogilvie, K. W.; Coplan, M. A.; Bochsler, P.; Geiss, J. 1989-01-01 The principal observations obtained by the Ion Composition Instrument (ICI) flown on the ISEE-3/ICE spacecraft, which was in the solar wind from September 1978 to the end of 1982, before being directed to the far magnetotail of the Earth are discussed. Almost continuous observations were made of the abundances of 3He++, 4He++, O6+, O7+, Ne, Si and Fe in various charge states, and of their bulk speeds and temperatures. The results show that there is a strong tendency in the collisionless solar wind for the ionic temperatures to be proportional to the masses. For heavier ions these temperatures exceed typical coronal electron temperatures. 4He++, especially in high speed streams, moves faster than H+, and travels at the same speed as heavier ions. The mechanism leading to this heating and rapid streaming is still not entirely clear. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900033060&hterms=ici&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dici','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900033060&hterms=ici&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dici">Solar wind observations with the ion composition instrument aboard the ISEE-3/ICE spacecraft</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ogilvie, K. W.; Coplan, M. A.; Bochsler, P.; Geiss, J. 1989-01-01 The principal observations obtained by the Ion Composition Instrument (ICI) flown on the ISEE-3/ICE spacecraft, which was in the solar wind from September 1978 to the end of 1982, before being directed to the far magnetotail of the Earth are discussed. Almost continuous observations were made of the abundances of 3He++, 4He++, 06+, 07+, Ne, Si and Fe in various charge states, and of their bulk speeds and temperatures. The results show that there is a strong tendency in the collisionless solar wind for the ionic temperatures to be proportional to the masses. For heavier ions these temperatures exceed typical coronal electron temperatures. 4He++, especially in high speed streams, moves faster than H+, and travels at the same speed as heavier ions. The mechanism leading to this heating and rapid streaming is still not entirely clear. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRA..115.8227F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRA..115.8227F">Magnetosheath for almost-aligned solar wind magnetic field and flow vectors: Wind observations across the dawnside magnetosheath at X = -12 Re</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Farrugia, C. J.; Erkaev, N. V.; Torbert, R. B.; Biernat, H. K.; Gratton, F. T.; Szabo, A.; Kucharek, H.; Matsui, H.; Lin, R. P.; Ogilvie, K. W.; Lepping, R. P.; Smith, C. W. 2010-08-01 While there are many approximations describing the flow of the solar wind past the magnetosphere in the magnetosheath, the case of perfectly aligned (parallel or anti-parallel) interplanetary magnetic field (IMF) and solar wind flow vectors can be treated exactly in a magnetohydrodynamic (MHD) approach. In this work we examine a case of nearly-opposed (to within 15°) interplanetary field and flow vectors, which occurred on October 24-25, 2001 during passage of the last interplanetary coronal mass ejection in an ejecta merger. Interplanetary data are from the ACE spacecraft. Simultaneously Wind was crossing the near-Earth (X ˜ -13 Re) geomagnetic tail and subsequently made an approximately 5-hour-long magnetosheath crossing close to the ecliptic plane (Z = -0.7 Re). Geomagnetic activity was returning steadily to quiet, “ground” conditions. We first compare the predictions of the Spreiter and Rizzi theory with the Wind magnetosheath observations and find fair agreement, in particular as regards the proportionality of the magnetic field strength and the product of the plasma density and bulk speed. We then carry out a small-perturbation analysis of the Spreiter and Rizzi solution to account for the small IMF components perpendicular to the flow vector. The resulting expression is compared to the time series of the observations and satisfactory agreement is obtained. We also present and discuss observations in the dawnside boundary layer of pulsed, high-speed (v ˜ 600 km/s) flows exceeding the solar wind flow speeds. We examine various generating mechanisms and suggest that the most likely cause is a wave of frequency 3.2 mHz excited at the inner edge of the boundary layer by the Kelvin-Helmholtz instability. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SoPh..293...85Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SoPh..293...85Z">Indirect Solar Wind Measurements Using Archival Cometary Tail Observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zolotova, Nadezhda; Sizonenko, Yuriy; Vokhmyanin, Mikhail; Veselovsky, Igor 2018-05-01 This paper addresses the problem of the solar wind behaviour during the Maunder minimum. Records on plasma tails of comets can shed light on the physical parameters of the solar wind in the past. We analyse descriptions and drawings of comets between the eleventh and eighteenth century. To distinguish between dust and plasma tails, we address their colour, shape, and orientation. Based on the calculations made by F.A. Bredikhin, we found that cometary tails deviate from the antisolar direction on average by more than 10°, which is typical for dust tails. We also examined the catalogues of Hevelius and Lubieniecki. The first indication of a plasma tail was revealed only for the great comet C/1769 P1. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.1628L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.1628L">Flow Sources of The Solar Wind Stream Structieres</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lotova, N. A.; Obridko, V. N.; Vladimirskii, K. V. 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980007565','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980007565">Mapping the Solar Wind from its Source Region into the Outer Corona</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Esser, Ruth 1997-01-01 Knowledge of the radial variation of the plasma conditions in the coronal source region of the solar wind is essential to exploring coronal heating and solar wind acceleration mechanisms. The goal of the proposal was to determine as many plasma parameters in the solar wind acceleration region and beyond as possible by coordinating different observational techniques, such as Interplanetary Scintillation Observations, spectral line intensity observations, polarization brightness measurements and X-ray observations. The inferred plasma parameters were then used to constrain solar wind models. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810060080&hterms=Solar+power+filters&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSolar%2Bpower%2Bfilters','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810060080&hterms=Solar+power+filters&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSolar%2Bpower%2Bfilters">Solar wind control of auroral zone geomagnetic activity</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Clauer, C. R.; Mcpherron, R. L.; Searls, C.; Kivelson, M. G. 1981-01-01 Solar wind magnetosphere energy coupling functions are analyzed using linear prediction filtering with 2.5 minute data. The relationship of auroral zone geomagnetic activity to solar wind power input functions are examined, and a least squares prediction filter, or impulse response function is designed from the data. Computed impulse response functions are observed to have characteristics of a low pass filter with time delay. The AL index is found well related to solar wind energy functions, although the AU index shows a poor relationship. High frequency variations of auroral indices and substorm expansions are not predictable with solar wind information alone, suggesting influence by internal magnetospheric processes. Finally, the epsilon parameter shows a poorer relationship with auroral geomagnetic activity than a power parameter, having a VBs solar wind dependency. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020084967&hterms=Nonuniformity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DNonuniformity','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020084967&hterms=Nonuniformity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DNonuniformity">Nature of Fluctuations on Directional Discontinuities Inside a Solar Ejection: Wind and IMP 8 Observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Vasquez, Bernard J.; Farrugia, Charles J.; Markovskii, Sergei A.; Hollweg, Joseph V.; Richardson, Ian G.; Ogilvie, Keith W.; Lepping, Ronald P.; Lin, Robert P.; Larson, Davin; White, Nicholas E. (Technical Monitor) 2001-01-01 A solar ejection passed the Wind spacecraft between December 23 and 26, 1996. On closer examination, we find a sequence of ejecta material, as identified by abnormally low proton temperatures, separated by plasmas with typical solar wind temperatures at 1 AU. Large and abrupt changes in field and plasma properties occurred near the separation boundaries of these regions. At the one boundary we examine here, a series of directional discontinuities was observed. We argue that Alfvenic fluctuations in the immediate vicinity of these discontinuities distort minimum variance normals, introducing uncertainty into the identification of the discontinuities as either rotational or tangential. Carrying out a series of tests on plasma and field data including minimum variance, velocity and magnetic field correlations, and jump conditions, we conclude that the discontinuities are tangential. Furthermore, we find waves superposed on these tangential discontinuities (TDs). The presence of discontinuities allows the existence of both surface waves and ducted body waves. Both probably form in the solar atmosphere where many transverse nonuniformities exist and where theoretically they have been expected. We add to prior speculation that waves on discontinuities may in fact be a common occurrence. In the solar wind, these waves can attain large amplitudes and low frequencies. We argue that such waves can generate dynamical changes at TDs through advection or forced reconnection. The dynamics might so extensively alter the internal structure that the discontinuity would no longer be identified as tangential. Such processes could help explain why the occurrence frequency of TDs observed throughout the solar wind falls off with increasing heliocentric distance. The presence of waves may also alter the nature of the interactions of TDs with the Earth's bow shock in so-called hot flow anomalies. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080045448&hterms=terminator&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dterminator','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080045448&hterms=terminator&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dterminator">Neutral Solar Wind Generated by Lunar Exospheric Dust at the Terminator</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Collier, Michael R.; Stubbs, Timothy J. 2007-01-01 We calculate the flux of neutral solar wind observed on the lunar surface at the terminator due to solar wind protons penetrating exospheric dust with: (1) grains larger that 0.1 microns and (2) grains larger than 0.01 microns. For grains larger than 0.1 microns, the ratio of the neutral solar wind to solar wind flux is estimated to be approx.10(exp -4)-10(exp -3) at solar wind speeds in excess of 800 km/s, but much lower (less than 10(exp -5) at average to low solar wind speeds. However, when the smaller grain sizes are considered, the ratio of the neutral solar wind flux to solar wind flux is estimated to be greater than or equal to 10(exp -5) at all speeds and at speeds in excess of 700 km/s reaches 10(exp -3)-10(exp -2). These neutral solar wind fluxes are easily measurable with current low energy neutral atom instrumentation. Observations of neutral solar wind from the surface of the Moon could provide a very sensitive determination of the distribution of very small dust grains in the lunar exosphere and would provide data complementary to optical measurements at ultraviolet and visible wavelengths. Furthermore, neutral solar wind, unlike its ionized counterpart, is .not held-off by magnetic anomalies, and may contribute to greater space weathering than expected in certain lunar locations. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021399&hterms=solar+energy+effective&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsolar%2Benergy%2Beffective','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021399&hterms=solar+energy+effective&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsolar%2Benergy%2Beffective">Solar wind: Internal parameters driven by external source</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chertkov, A. D. 1995-01-01 A new concept interpreting solar wind parameters is suggested. The process of increasing twofold of a moving volume in the solar wind (with energy transfer across its surface which is comparable with its whole internal energy) is a more rapid process than the relaxation for the pressure. Thus, the solar wind is unique from the point of view of thermodynamics of irreversible processes. The presumptive source of the solar wind creation - the induction electric field of the solar origin - has very low entropy. The state of interplanetary plasma must be very far from the thermodynamic equilibrium. Plasma internal energy is contained mainly in non-degenerate forms (plasma waves, resonant plasma oscillations, electric currents). Microscopic oscillating electric fields in the solar wind plasma should be about 1 V/m. It allows one to describe the solar wind by simple dissipative MHD equations with small effective mean free path (required for hydrodynamical description), low value of electrical conductivity combined with very big apparent thermal conductivity (required for observed solar wind acceleration). These internal parameters are interrelated only due to their origin: they are externally driven. Their relation can change during the interaction of solar wind plasma with an obstacle (planet, spacecraft). The concept proposed can be verified by the special electric field measurements, not ruining the primordial plasma state. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22590899-anomalously-low-sup-sup-ratio-solar-wind-ace-swics-observation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22590899-anomalously-low-sup-sup-ratio-solar-wind-ace-swics-observation">Anomalously low C{sup 6+}/C{sup 5+} ratio in solar wind: ACE/SWICS observation</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Zhao, L., E-mail: lzh@umich.edu; Landi, E.; Kocher, M. The Carbon and Oxygen ionization states in the solar wind plasma freeze-in within 2 solar radii (R{sub s}) from the solar surface, and then they do not change as they propagate with the solar wind into the heliosphere. Therefore, the O{sup 7+}/O{sup 6+} and C{sup 6+}/C{sup 5+} charge state ratios measured in situ maintain a record of the thermal properties (electron temperature and density) of the inner corona where the solar wind originates. Since these two ratios freeze-in at very similar height, they are expected to be correlated. However, an investigation of the correlation between these two ratios as measuredmore » by ACE/SWICS instrument from 1998 to 201l shows that there is a subset of “Outliers” departing from the expected correlation. We find about 49.4% of these Outliers is related to the Interplanetary Coronal Mass Ejections (ICMEs), while 49.6% of them is slow speed wind (V{sub p} < 500 km/s) and about 1.0% of them is fast solar wind (V{sub p} > 500 km/s). We compare the outlier-slow-speed wind with the normal slow wind (defined as V{sub p} < 500 km/s and O{sup 7+}/O{sup 6+} > 0.2) and find that the reason that causes the Outliers to depart from the correlation is their extremely depleted C{sup 6+}/C{sup 5+} ratio which is decreased by 80% compared to the normal slow wind. We discuss the implication of the Outlier solar wind for the solar wind acceleration mechanism.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.P32A..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.P32A..01S">The solar wind - Moon interaction discovered by MAP-PACE on KAGUYA</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Saito, Y.; Yokota, S.; Tanaka, T.; Asamura, K.; Nishino, M. N.; Yamamoto, T.; Tsunakawa, H.; Shibuya, H.; Shimizu, H.; Takahashi, F. 2009-12-01 Magnetic field And Plasma experiment - Plasma energy Angle and Composition Experiment (MAP-PACE) on KAGUYA (SELENE) completed its ˜1.5-year observation of the low energy charged particles around the Moon. SELENE was successfully launched on 14 September 2007 by H2A launch vehicle from Tanegashima Space Center in Japan. SELENE was inserted into a circular lunar polar orbit of 100km altitude and continued observation for nearly 1.5 years till it impacted the Moon on 10 June 2009. During the last 5 months, the orbit was lowered to ˜50km-altitude between January 2009 and April 2009, and some orbits had further lower perilune altitude of ˜10km after April 2009. The newly observed data showed characteristic ion distributions around the Moon. Besides the solar wind, one of the MAP-PACE sensors MAP-PACE-IMA (Ion Mass Analyzer) discovered four clearly distinguishable ion distributions on the dayside of the Moon: 1) Solar wind ions backscattered at the lunar surface, 2) Solar wind ions reflected by magnetic anomalies on the lunar surface, 3) Ions that are originating from the reflected / backscattered solar wind ions and are pick-up accelerated by the solar wind convection electric field, and 4) Ions originating from the lunar surface / lunar atmosphere. One of the most important discoveries of the ion mass spectrometer (MAP-PACE-IMA) is the first in-situ measurements of the alkali ions originating from the Moon surface / atmosphere. The ions generated on the lunar surface by solar wind sputtering, solar photon stimulated desorption, or micro-meteorite vaporization are accelerated by the solar wind convection electric field and detected by IMA. The mass profiles of these ions show ions including He+, C+, O+, Na+, and K+/Ar+. The heavy ions were also observed when the Moon was in the Earth’s magnetotail where no solar wind ions impinged on the lunar surface. This discovery strongly restricts the possible generation mechanisms of the ionized alkali atmosphere around the </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840004999','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840004999">Solar Wind Five</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Neugebauer, M. (Editor) 1983-01-01 Topics of discussion were: solar corona, MHD waves and turbulence, acceleration of the solar wind, stellar coronae and winds, long term variations, energetic particles, plasma distribution functions and waves, spatial dependences, and minor ions. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E3557V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E3557V">Sources of the solar wind - the heliospheric point of view</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Von Steiger, Rudolf; Shearer, Paul; Zurbuchen, Thomas The solar wind as observed in the heliosphere has several properties that can be interpreted as signatures of conditions and processes at its source in the solar atmosphere. Traditionally it has been customary to distinguish between solar wind types solely based on its speed, "fast" and "slow" wind. Over the last couple of decades new instruments resolving not only the main constituents (protons and alpha particles) but also heavy ions from C to Fe have added new observables, in particular the charge state and elemental composition of these ions. The charge states are indicators of the coronal temperature at the source region; they have confirmed that the "fast" wind emanates from the relatively cool coronal hole regions, while the "slow" wind originates from hotter sources such as the streamer belt and active regions. Thus they are more reliable indicators of solar wind source than the speed alone could be because they readily discriminate between "fast" wind from coronal holes and fast coronal mass ejections (CMEs). The elemental composition in the solar wind compared to the abundances in the photosphere shows a typical fractionation that depends on the first ionization potential (FIP) of the elements. Since that fractionation occurs beneath the corona, in the chromosphere, its strength is indicative of the conditions in that layer. While the "fast" wind is very similar to photospheric composition, the fractionation of the "slow" wind and of CMEs is higher and strongly variable. We will review the observations of the SWICS composition instruments on both the ACE and the Ulysses missions, which have made composition observations between 1 and 5 AU and at all latitudes in the heliosphere over the last two decades. Specifically, analysis of the "slow" wind observations at all time scales, from hours to complete solar cycles, will be used to better characterize its source regions. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120016041','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120016041">Near-Earth Solar Wind Flows and Related Geomagnetic Activity During more than Four Solar Cycles (1963-2011)</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Richardson, Ian G.; Cane, Hilary V. 2012-01-01 In past studies, we classified the near-Earth solar wind into three basic flow types based on inspection of solar wind 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 solar wind, 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 solar wind 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 solar wind observations, thereby encompassing the complete solar cycles 20 to 23 and the ascending phase of cycle 24. We discuss the cycle-to-cycle variations in near-Earth solar wind structures and l1e related geomagnetic activity over more than four solar cycles, updating some of the results of our earlier studies. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active">6</li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active">7</li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870052836&hterms=wind+monitor&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870052836&hterms=wind+monitor&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwind%2Bmonitor">Solar wind parameters and magnetospheric coupling studies</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> King, Joseph H. 1986-01-01 This paper presents distributions, means, and standard deviations of the fluxes of solar wind protons, momentum, and energy as observed near earth during the solar quiet and active years 1976 and 1979. Distributions of ratios of energies (Alfven Mach number, plasma beta) and distributions of interplanetary magnetic field orientations are also given. Finally, the uncertainties associated with the use of the libration point orbiting ISEE-3 spacecraft as a solar wind monitor are discussed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ERL.....9e5004S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ERL.....9e5004S">Evidence for solar wind modulation of lightning</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Scott, C. J.; Harrison, R. G.; Owens, M. J.; Lockwood, M.; Barnard, L. 2014-05-01 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 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.2141R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.2141R">Intermittency of solar wind on scale 0.01-16 Hz.</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Riazantseva, Maria; Zastenker, Georgy; Chernyshov, Alexander; Petrosyan, Arakel Magnetosphere of the Earth is formed in the process of solar wind flow around earth's magnetic field. Solar wind is a flow of turbulent plasma that displays a multifractal structure and an intermittent character. That is why the study of the characteristics of solar wind turbulence is very important part of the solution of the problem of the energy transport from the solar wind to magnetosphere. A large degree of intermittency is observed in the solar wind ion flux and magnetic field time rows. We investigated the intermittency of solar wind fluctuations under large statistics of high time resolution measurements onboard Interball-1 spacecraft on scale from 0.01 to 16 Hz. Especially it is important that these investigation is carry out for the first time for the earlier unexplored (by plasma data) region of comparatively fast variations (frequency up to 16 Hz), so we significantly extend the range of intermittency observations for solar wind plasma. The intermittency practically absent on scale more then 1000 s and it grows to the small scales right up till t 30-60 s. The behavior of the intermittency for the scale less then 30-60 s is rather changeable. The boundary between these two rates of intermittency is quantitatively near to the well-known boundary between the dissipation and inertial scales of fluctuations, what may point to their possible relation. Special attention is given to a comparison of intermittency for solar wind observation intervals containing SCIF (Sudden Changes of Ion Flux) to ones for intervals without SCIF. Such a comparison allows one to reveal the fundamental turbulent properties of the solar wind regions in which SCIF is observed more frequently. We use nearly incompressible model of the solar wind turbulence for obtained data interpretation. The regime when density fluctuations are passive scalar in a hydrodynamic field of velocity is realized in turbulent solar wind flows according to this model. This hypothesis can be verified </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-10-10/pdf/2012-24829.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-10-10/pdf/2012-24829.pdf">77 FR 61597 - Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind...</a> <a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a> 2012-10-10 ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL12-109-000] Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind Lessee, LLC; Pacific Wind 2, LLC; Valentine Solar, LLC; EDF Renewable Development, Inc.; Notice of Petition for Declaratory... </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.3727S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.3727S">Magnetosheath Propagation Time of Solar Wind Directional Discontinuities</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Samsonov, A. A.; Sibeck, D. G.; Dmitrieva, N. P.; Semenov, V. S.; Slivka, K. Yu.; Å afránkova, J.; Němeček, Z. 2018-05-01 Observed delays in the ground response to solar wind directional discontinuities have been explained as the result of larger than expected magnetosheath propagation times. Recently, Samsonov et al. (2017, https://doi.org/10.1002/2017GL075020) showed that the typical time for a southward interplanetary magnetic field (IMF) turning to propagate across the magnetosheath is 14 min. Here by using a combination of magnetohydrodynamic simulations, spacecraft observations, and analytic calculations, we study the dependence of the propagation time on solar wind parameters and near-magnetopause cutoff speed. Increases in the solar wind speed result in greater magnetosheath plasma flow velocities, decreases in the magnetosheath thickness and, as a result, decreases in the propagation time. Increases in the IMF strength result in increases in the magnetosheath thickness and increases in the propagation time. Both magnetohydrodynamic simulations and observations suggest that propagation times are slightly smaller for northward IMF turnings. Magnetosheath flow deceleration must be taken into account when predicting the arrival times of solar wind structures at the dayside magnetopause. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4508929','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4508929">Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Owens, M J; Horbury, T S; Wicks, R T; McGregor, S L; Savani, N P; Xiong, M 2014-01-01 Advanced forecasting of space weather requires simulation of the whole Sun-to-Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large-scale solar wind structures, which can be captured by solar wind models, and small-scale solar wind “noise,” which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical “downscaling” of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small-scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model-independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme. Key Points Solar wind models must be downscaled in order to drive magnetospheric models Ensemble downscaling is more effective than deterministic downscaling The magnetosphere responds nonlinearly to small-scale solar wind fluctuations PMID:26213518 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26213518','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26213518">Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Owens, M J; Horbury, T S; Wicks, R T; McGregor, S L; Savani, N P; Xiong, M 2014-06-01 Advanced forecasting of space weather requires simulation of the whole Sun-to-Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large-scale solar wind structures, which can be captured by solar wind models, and small-scale solar wind "noise," which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical "downscaling" of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small-scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model-independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme. Solar wind models must be downscaled in order to drive magnetospheric models Ensemble downscaling is more effective than deterministic downscaling The magnetosphere responds nonlinearly to small-scale solar wind fluctuations. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22661310-turbulent-transport-three-dimensional-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22661310-turbulent-transport-three-dimensional-solar-wind">Turbulent Transport in a Three-dimensional Solar Wind</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Shiota, D.; Zank, G. P.; Adhikari, L. 2017-03-01 Turbulence in the solar wind can play essential roles in the heating of coronal and solar wind plasma and the acceleration of the solar wind and energetic particles. Turbulence sources are not well understood and thought to be partly enhanced by interaction with the large-scale inhomogeneity of the solar wind and the interplanetary magnetic field and/or transported from the solar corona. To investigate the interaction with background inhomogeneity and the turbulence sources, we have developed a new 3D MHD model that includes the transport and dissipation of turbulence using the theoretical model of Zank et al. We solve for themore » temporal and spatial evolution of three moments or variables, the energy in the forward and backward fluctuating modes and the residual energy and their three corresponding correlation lengths. The transport model is coupled to our 3D model of the inhomogeneous solar wind. We present results of the coupled solar wind-turbulence model assuming a simple tilted dipole magnetic configuration that mimics solar minimum conditions, together with several comparative intermediate cases. By considering eight possible solar wind and turbulence source configurations, we show that the large-scale solar wind and IMF inhomogeneity and the strength of the turbulence sources significantly affect the distribution of turbulence in the heliosphere within 6 au. We compare the predicted turbulence distribution results from a complete solar minimum model with in situ measurements made by the Helios and Ulysses spacecraft, finding that the synthetic profiles of the turbulence intensities show reasonable agreement with observations.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12211468M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12211468M">Solar Illumination Control of the Polar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Maes, L.; Maggiolo, R.; DeÂ Keyser, J.; André, M.; Eriksson, A. I.; Haaland, S.; Li, K.; Poedts, S. 2017-11-01 Polar wind outflow is an important process through which the ionosphere supplies plasma to the magnetosphere. The main source of energy driving the polar wind is solar illumination of the ionosphere. As a result, many studies have found a relation between polar wind flux densities and solar EUV intensity, but less is known about their relation to the solar zenith angle at the ionospheric origin, certainly at higher altitudes. The low energy of the outflowing particles and spacecraft charging means it is very difficult to measure the polar wind at high altitudes. We take advantage of an alternative method that allows estimations of the polar wind flux densities far in the lobes. We analyze measurements made by the Cluster spacecraft at altitudes from 4 up to 20 RE. We observe a strong dependence on the solar zenith angle in the ion flux density and see that both the ion velocity and density exhibit a solar zenith angle dependence as well. We also find a seasonal variation of the flux density. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22518793-turbulence-solar-wind-measured-comet-tail-test-particles','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22518793-turbulence-solar-wind-measured-comet-tail-test-particles">TURBULENCE IN THE SOLAR WIND MEASURED WITH COMET TAIL TEST PARTICLES</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> DeForest, C. E.; Howard, T. A.; Matthaeus, W. H. 2015-10-20 By analyzing the motions of test particles observed remotely in the tail of Comet Encke, we demonstrate that the solar wind undergoes turbulent processing enroute from the Sun to the Earth and that the kinetic energy entrained in the large-scale turbulence is sufficient to explain the well-known anomalous heating of the solar wind. Using the heliospheric imaging (HI-1) camera on board NASA's STEREO-A spacecraft, we have observed an ensemble of compact features in the comet tail as they became entrained in the solar wind near 0.4 AU. We find that the features are useful as test particles, via mean-motion analysismore » and a forward model of pickup dynamics. Using population analysis of the ensemble's relative motion, we find a regime of random-walk diffusion in the solar wind, followed, on larger scales, by a surprising regime of semiconfinement that we attribute to turbulent eddies in the solar wind. The entrained kinetic energy of the turbulent motions represents a sufficient energy reservoir to heat the solar wind to observed temperatures at 1 AU. We determine the Lagrangian-frame diffusion coefficient in the diffusive regime, derive upper limits for the small scale coherence length of solar wind turbulence, compare our results to existing Eulerian-frame measurements, and compare the turbulent velocity with the size of the observed eddies extrapolated to 1 AU. We conclude that the slow solar wind is fully mixed by turbulence on scales corresponding to a 1–2 hr crossing time at Earth; and that solar wind variability on timescales shorter than 1–2 hr is therefore dominated by turbulent processing rather than by direct solar effects.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026730','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026730">Observation of pick-up ions in the solar wind: Evidence for the source of the anomalous cosmic ray component?</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hovestadt, D.; Moebius, E.; Klecker, B.; Scholer, M.; Gloeckler, G.; Ipavich, F. M. 1985-01-01 Singly ionized energetic helium has been observed in the solar wind by using the time of flight spectrometer SULEICA on the AMPTE/IRM satellite between September and December, 1984. The energy density spectrum shows a sharp cut off which is strongly correlated with the four fold solar wind bulk energy. The absolute flux of the He(+)ions of about 10000 ion/sq cm.s is present independent of the IPL magnetic field orientation. The most likely source is the neutral helium of the interstellar wind which is ionized by solar UV radiation. It is suggested that these particles represent the source of the anomalous cosmic ray component. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080047936&hterms=solar+energy+effective&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Benergy%2Beffective','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080047936&hterms=solar+energy+effective&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Benergy%2Beffective">Observational and Theoretical Challenges to Wave or Turbulence Accelerations of the Fast Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Roberts, D. Aaron 2008-01-01 We use both observations and theoretical considerations to show that hydromagnetic waves or turbulence cannot produce the acceleration of the fast solar wind and the related heating of the open solar corona. Waves do exist as shown by Hinode and other observations, and can play a role in the differential heating and acceleration of minor ions but their amplitudes are not sufficient to power the wind, as demonstrated by extrapolation of magnetic spectra from Helios and Ulysses observations. Dissipation mechanisms invoked to circumvent this conclusion cannot be effective for a variety of reasons. In particular, turbulence does not play a strong role in the corona as shown by both eclipse observations of coronal striations and theoretical considerations of line-tying to a nonturbulent photosphere, nonlocality of interactions, and the nature of kinetic dissipation. In the absence of wave heating and acceleration, the chromosphere and transition region become the natural source of open coronal energization. We suggest a variant of the velocity filtration approach in which the emergence and complex churning of the magnetic flux in the chromosphere and transition region continuously and ubiquitously produces the nonthermal distributions required. These particles are then released by magnetic carpet reconnection at a wide range of scales and produce the wind as described in kinetic approaches. Since the carpet reconnection is not the main source of the energization of the plasma, there is no expectation of an observable release of energy in nanoflares. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.1156V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.1156V">Solar wind influence on Jupiter's magnetosphere and aurora</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Vogt, Marissa; Gyalay, Szilard; Withers, Paul 2016-04-01 Jupiter's magnetosphere is often said to be rotationally driven, with strong centrifugal stresses due to large spatial scales and a rapid planetary rotation period. For example, the main auroral emission at Jupiter is not due to the magnetosphere-solar wind interaction but is driven by a system of corotation enforcement currents that arises to speed up outflowing Iogenic plasma. Additionally, processes like tail reconnection are also thought to be driven, at least in part, by processes internal to the magnetosphere. While the solar wind is generally expected to have only a small influence on Jupiter's magnetosphere and aurora, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the position and brightness of the UV auroral emissions. We will report on the results of a comprehensive, quantitative study of the influence of the solar wind on various magnetospheric data sets measured by the Galileo mission from 1996 to 2003. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter, we have identified intervals of high and low solar wind dynamic pressure. We can use this information to quantify how a magnetospheric compression affects the magnetospheric field configuration, which in turn will affect the ionospheric mapping of the main auroral emission. We also consider whether there is evidence that reconnection events occur preferentially during certain solar wind conditions or that the solar wind modulates the quasi-periodicity seen in the magnetic field dipolarizations and flow bursts. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH52A..03V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH52A..03V">The Slow and Fast Solar Wind Boundary, Corotating Interaction Regions, and Coronal Mass Ejection observations with Solar Probe Plus and Solar Orbiter (Invited)</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Velli, M. M. 2013-12-01 The Solar Probe Plus and Solar Orbiter missions have as part of their goals to understand the source regions of the solar wind and of the heliospheric magnetic field. In the heliosphere, the solar wind is made up of interacting fast and slow solar wind streams as well as a clearly intermittent source of flow and field, arising from coronal mass ejections (CMEs). In this presentation a summary of the questions associated with the distibution of wind speeds and magnetic fields in the inner heliosphere and their origin on the sun will be summarized. Where and how does the sharp gradient in speeds develop close to the Sun? Is the wind source for fast and slow the same, and is there a steady component or is its origin always intermittent in nature? Where does the heliospheric current sheet form and how stable is it close to the Sun? What is the distribution of CME origins and is there a continuum from large CMEs to small blobs of plasma? We will describe our current knowledge and discuss how SPP and SO will contribute to a more comprehensive understanding of the sources of the solar wind and magnetic fields in the heliosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070020281&hterms=exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dexchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070020281&hterms=exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dexchange">Chandra Observations of Comet 2P/Encke 2003: First Detection of a Collisionally Thin, Fast Solar Wind Charge Exchange System</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lisse, C. M.; Christian, D. J.; Deneri, K.; Wolk, S. J.; Bodewits, D.; Hoekstra, R.; Combi, M. R.; Makinen, T.; Dryer, M.; Fry, C. D.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20070020281'); toggleEditAbsImage('author_20070020281_show'); toggleEditAbsImage('author_20070020281_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20070020281_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20070020281_hide"> 2005-01-01 We report the results of 15 hr of Chandra observations of comet 2P/Encke 2003 on November 24. X-ray emission from comet Encke was resolved on scales of 500-40,000 km, with unusual morphology due to the presence of a low-density, collisionally thin (to charge exchange) coma. A light curve with peak-to-peak amplitude of 20% consistent with a nucleus rotational period of 11.1 hr was found, further evidence for a collisionally thin coma. We confirm emission lines due to oxygen and neon in the 800-1000 eV range but find very unusual oxygen and carbon line ratios in the 200-700 eV range, evidence for low-density, high effective temperature solar wind composition. We compare the X-ray spectral observation results to contemporaneous measurements of the coma and solar wind made by other means and find good evidence for the dominance of a postshock bubble of expanding solar wind plasma, moving at 600 km/s with charge state composition between that of the "fast" and "slow" solar winds. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25628139','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25628139">Direct evidence for kinetic effects associated with solar wind reconnection.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Xu, Xiaojun; Wang, Yi; Wei, Fengsi; Feng, Xueshang; Deng, Xiaohua; Ma, Yonghui; Zhou, Meng; Pang, Ye; Wong, Hon-Cheng 2015-01-28 Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas. In-situ observations in the Earth's magnetosphere provide solid consistence with theoretical models on the point that kinetic effects are required in the collisionless reconnection. However, all the observations associated with solar wind reconnection have been analyzed in the context of magnetohydrodynamics (MHD) although a lot of solar wind reconnection exhausts have been reported. Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown. Here, by dual-spacecraft observations, we report a solar wind reconnection with clear Hall magnetic fields. Its corresponding Alfvenic electron outflow jet, derived from the decouple between ions and electrons, is identified, showing direct evidence for kinetic effects that dominate the collisionless reconnection. The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820028333&hterms=1087&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231087','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820028333&hterms=1087&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231087">Correlations between solar wind parameters and auroral kilometric radiation intensity</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gallagher, D. L.; Dangelo, N. 1981-01-01 The relationship between solar wind properties and the influx of energy into the nightside auroral region as indicated by the intensity of auroral kilometric radiation is investigated. Smoothed Hawkeye satellite observations of auroral radiation at 178, 100 and 56.2 kHz for days 160 through 365 of 1974 are compared with solar wind data from the composite Solar Wind Plasma Data Set, most of which was supplied by the IMP-8 spacecraft. Correlations are made between smoothed daily averages of solar wind ion density, bulk flow speed, total IMF strength, electric field, solar wind speed in the southward direction, solar wind speed multiplied by total IMF strength, the substorm parameter epsilon and the Kp index. The greatest correlation is found between solar wind bulk flow speed and auroral radiation intensity, with a linear correlation coefficient of 0.78 for the 203 daily averages examined. A possible mechanism for the relationship may be related to the propagation into the nightside magnetosphere of low-frequency long-wavelength electrostatic waves produced in the magnetosheath by the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021297&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021297&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bintensity%2Bmeasurement">Radio interferometer measurements of turbulence in the inner solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spangler, S. R.; Sakurai, T.; Coles, William A.; Grall, R. R.; Harmon, J. K. 1995-01-01 Measurements can be made of Very Long Baseline Interferometer (VLBI) phase scintillations due to plasma turbulence in the solar corona and solar wind. These measurements provide information on the spectrum and intensity of density fluctuations with scale sizes of a few hundred to several thousand kilometers. If we model the spatial power spectrum of the density fluctuations as P(sub delta n)(q) = C(sup 2)(sub N) q(sup -alpha), where q is the spatial wavenumber, these observations yield both alpha and the path-integrated value of C(sup 2)(sub N). The recently completed Very Long Baseline Array (VLBA) is capable of making such measurements over the heliocentric distance range from a few solar radii to 60 solar radii and beyond. This permits the determination with the same technique and instrument of the radial evolution of turbulent characteristics, as well as their dependence on solar wind transients, sector structure, etc. In this paper we present measurements of 13 sources observed at a wide range of solar elongations, and at different times. These observations show that the coefficient C(sup 2(sub N), depends on heliocentric distance as approximately C(sup 2)(sub N) varies as (R/Solar Radius)(sup -3.7). The radio derived power spectral characteristics are in agreement with in situ measurements by the Helios spacecraft for regions of slow solar wind, but fast solar wind does not have large enough density fluctuations to account for the magnitude of the observed scintillations. The observed radial dependence is consistent with a WKB-type evolution of the turbulence with heliocentric distance. Our data also show indication of turbulence enhancement associated with solar wind transients. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830052897&hterms=ACCOUNTS+CHARGE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DACCOUNTS%2BBY%2BCHARGE','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830052897&hterms=ACCOUNTS+CHARGE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DACCOUNTS%2BBY%2BCHARGE">Charge exchange in solar wind-cometary interactions</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gombosi, T. I.; Horanyi, M.; Kecskemety, K.; Cravens, T. E.; Nagy, A. F. 1983-01-01 A simple model of a cometary spherically symmetrical atmosphere and ionosphere is considered. An analytic solution of the governing equations describing the radial distribution of the neutral and ion densities is found. The new solution is compared to the well-known solution of the equations containing only ionization terms. Neglecting recombination causes a significant overestimate of the ion density in the vicinity of the comet. An axisymmetric model of the solar wind-cometary interaction is considered, taking into account the loss of solar wind ions due to charge exchange. The calculations predict that for active comets, solar wind absorption due to charge exchange becomes important at a few thousand kilometers from the nucleus, and a surface separating the shocked solar wind from the cometary ionosphere develops in this region. These calculations are in reasonable agreement with the few observations available for the ionopause location at comets. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.832H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.832H">Observations & modeling of solar-wind/magnetospheric interactions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hoilijoki, Sanni; Von Alfthan, Sebastian; Pfau-Kempf, Yann; Palmroth, Minna; Ganse, Urs 2016-07-01 The majority of the global magnetospheric dynamics is driven by magnetic reconnection, indicating the need to understand and predict reconnection processes and their global consequences. So far, global magnetospheric dynamics has been simulated using mainly magnetohydrodynamic (MHD) models, which are approximate but fast enough to be executed in real time or near-real time. Due to their fast computation times, MHD models are currently the only possible frameworks for space weather predictions. However, in MHD models reconnection is not treated kinetically. In this presentation we will compare the results from global kinetic (hybrid-Vlasov) and global MHD simulations. Both simulations are compared with in-situ measurements. We will show that the kinetic processes at the bow shock, in the magnetosheath and at the magnetopause affect global dynamics even during steady solar wind conditions. Foreshock processes cause an asymmetry in the magnetosheath plasma, indicating that the plasma entering the magnetosphere is not symmetrical on different sides of the magnetosphere. Behind the bow shock in the magnetosheath kinetic wave modes appear. Some of these waves propagate to the magnetopause and have an effect on the magnetopause reconnection. Therefore we find that kinetic phenomena have a significant role in the interaction between the solar wind and the magnetosphere. While kinetic models cannot be executed in real time currently, they could be used to extract heuristics to be added in the faster MHD models. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active">7</li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active">8</li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840004997','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840004997">Interpretation of 3He variations in the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Coplan, M. A.; Ogilvie, K. W.; Geiss, J.; Bochsler, P. 1983-01-01 The ion composition instrument (ICI) on ISEE-3 observed the isotopes of helium of mass 3 and 4 in the solar wind almost continuously between August 1978 and July 1982. This period included the increase towards the maximum of solar activity cycle 21, the maximum period, and the beginning of the descent towards solar minimum. Observations were made when the solar wind speed was between 300 and 620 km/s. For part of the period evidence for regular interplanetary magnetic sector structure was clear and a number of 3He flares occurred during this time. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4343301-recurrent-solar-wind-streams-observed-interplanetary-scintillation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/4343301-recurrent-solar-wind-streams-observed-interplanetary-scintillation">Recurrent solar wind streams observed by interplanetary scintillation of 3C 48</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Watanabe, T.; Kakinuma, T. 1972-10-01 The interplanetary scintillation of 3C 48 was observed by two spaced receivers (69.3 MHz) during February and March 1971. The recurrent property of the observed velocity increase of the solar wind is clearly seen, and their recurrent period is 24 to 25 days. This value is shorter than the synodic period of 27 days, but this deviation may be explained by the displacement of the closest point to the Sun on the line of sight for 3C 48. A comparison with the data of the wind velocity obtained by apace probes shows that the observed enhancements are associated with twomore » high-velocity streams corotating around the Sun. The enhancements of the scintillation index precede by about two days the velocity enhancements, and it may be concluded that such enhancement of the scintillation index has resulted from the compressed region of the interplanetary plasma formed in front of the high-velocity corotating stream. (auth)« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780039623&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dorbiting%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780039623&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dorbiting%2Bwind">Ion acoustic waves in the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gurnett, D. A.; Frank, L. A. 1978-01-01 Plasma wave measurements on the Helios 1 and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the Imp 6 spacecraft now provide strong evidence that these waves are shortwavelength ion acoustic waves which are Doppler-shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting Imp 6 and 8 spacecraft shows that the ion acoustic wave turbulence detected in interplanetary space has characteristics essentially identical to those of bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases, enhanced ion acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as was suggested by Forslund. Possible related mechanisms which could explain the generation of ion acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750007505','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750007505">The Third Solar Wind Conference: A summary</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Russell, C. T. 1974-01-01 The Third Solar Wind Conference consisted of nine sessions. The following subjects were discussed: (1) solar abundances; (2) the history and evolution of the solar wind; (3) the structure and dynamics of the solar corona; (4) macroscopic and microscopic properties of the solar wind; (5) cosmic rays as a probe of the solar wind; (6) the structure and dynamics of the solar wind; (7) spatial gradients; (8) stellar winds; and (9) interactions with objects in the solar wind. The invited and contributed talks presented at the conference are summarized. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.476.2465O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.476.2465O">The solar wind in time: a change in the behaviour of older winds?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> O'Fionnagáin, D.; Vidotto, A. A. 2018-05-01 In this paper, we model the wind of solar analogues at different ages to investigate the evolution of the solar wind. Recently, it has been suggested that winds of solar type stars might undergo a change in properties at old ages, whereby stars older than the Sun would be less efficient in carrying away angular momentum than what was traditionally believed. Adding to this, recent observations suggest that old solar-type stars show a break in coronal properties, with a steeper decay in X-ray luminosities and temperatures at older ages. We use these X-ray observations to constrain the thermal acceleration of winds of solar analogues. Our sample is based on the stars from the `Sun in Time' project with ages between 120 and 7000 Myr. The break in X-ray properties leads to a break in wind mass-loss rates (\\dot{M}) at roughly 2 Gyr, with \\dot{M} (t < 2 Gyr) ∝ t-0.74 and \\dot{M} (t > 2 Gyr) ∝ t-3.9. This steep decay in \\dot{M} at older ages could be the reason why older stars are less efficient at carrying away angular momentum, which would explain the anomalously rapid rotation observed in older stars. We also show that none of the stars in our sample would have winds dense enough to produce thermal emission above 1-2 GHz, explaining why their radio emissions have not yet been detected. Combining our models with dynamo evolution models for the magnetic field of the Earth, we find that, at early ages (≈100 Myr), our Earth had a magnetosphere that was three or more times smaller than its current size. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950053630&hterms=foreshock&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dforeshock','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950053630&hterms=foreshock&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dforeshock">A study of the solar wind deceleration in the Earth's foreshock region</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Zhang, T.-L.; Schwingenschuh, K.; Russell, C. T. 1995-01-01 Previous observations have shown that the solar wind is decelerated and deflected in the earth's upstream region populated by long-period waves. This deceleration is corelated with the 'diffuse' but not with the 'reflected' ion population. The speed of the solar wind may decrease tens of km/s in the foreshock region. The solar wind dynamic pressure exerted on the magnetopause may vary due to the fluctuation of the solar wind speed and density in the foreshock region. In this study, we examine this solar wind deceleration and determine how the solar wind deceleration varies in the foreshock region. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM13E4214E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM13E4214E">Ulysses Observations of Tripolar Guide-Magnetic Field Perturbations Across Solar Wind Reconnection Exhausts</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Eriksson, S.; Peng, B.; Markidis, S.; Gosling, J. T.; McComas, D. J.; Lapenta, G.; Newman, D. L. 2014-12-01 We report observations from 15 solar wind reconnection exhausts encountered along the Ulysses orbit beyond 4 AU in 1996-1999 and 2002-2005. The events, which lasted between 17 and 45 min, were found at heliospheric latitudes between -36o and 21o with one event detected as high as 58o. All events shared a common characteristic of a tripolar guide-magnetic field perturbation being detected across the observed exhausts. The signature consists of an enhanced guide field magnitude within the exhaust center and two regions of significantly depressed guide-fields adjacent to the center region. The events displayed magnetic field shear angles as low as 37o with a mean of 89o. This corresponds to a strong external guide field relative to the anti-parallel reconnecting component of the magnetic field with a mean ratio of 1.3 and a maximum ratio of 3.1. A 2-D kinetic reconnection simulation for realistic solar wind conditions reveals that tripolar guide fields form at current sheets in the presence of multiple X-lines as two magnetic islands interact with one another for such strong guide fields. The Ulysses observations are also compared with the results of a 3-D kinetic simulation of multiple flux ropes in a strong guide field. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH33A2762M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH33A2762M">Solar-Wind Observations of Collisional Thermalization among Multiple Ion-Species</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Maruca, B.; Qudzi, R.; Hellinger, P.; Stevens, M. L.; Kasper, J. C.; Korreck, K. E. 2017-12-01 The rate of Coulomb collisions among ions in the solar wind is low enough that significant departures from thermal equilibrium (e.g., different ion species having different temperatures) are frequently observed. Nevertheless, collisions have been found to play an important role in the plasma's large-scale evolution as it expands from the corona and through the heliosphere. Many statistical analyses have found that the temperature ratio of the two most abundant ions, protons (ionized hydrogen) and alpha-particles (fully ionized helium), is heavily influenced by collisional thermalization. This ongoing study expands on this work by including oxygen +6, which, during select periods (of cold, slow, dense plasma), the Wind spacecraft's Faraday Cups can measure at high cadences. Using well-established models of collisional relaxation, the in-situ measurements at 1 AU can be used to estimate ion conditions earlier in the plasma's expansion history. Assessing the physicality of these predictions can indicate to what degree preferential heating and/or heating beyond the corona affected the plasma's evolution. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH51E..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH51E..05S"> Mapping 3D plasma structure in the solar wind with the L1 constellation: joint observations from Wind, ACE, DSCOVR, and SoHO</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Stevens, M. L.; Kasper, J. C.; Case, A. W.; Korreck, K. E.; Szabo, A.; Biesecker, D. A.; Prchlik, J. 2017-12-01 At this moment in time, four observatories with similar instrumentation- Wind, ACE, DSCOVR, and SoHO- are stationed directly upstream of the Earth and making continuous observations. They are separated by drift-time baselines of seconds to minutes, timescales on which MHD instabilities in the solar wind are known to grow and evolve, and spatial baselines of tens to 200 earth radii, length scales relevant to the Earth's magnetosphere. By comparing measurements of matched solar wind structures from the four vantage points, the form of structures and associated dynamics on these scales is illuminated. Our targets include shocks and MHD discontinuities, stream fronts, locii of reconnection and exhaust flow boundary layers, plasmoids, and solitary structures born of nonlinear instability. We use the tetrahedral quality factors and other conventions adopted for Cluster to identify periods where the WADS constellation is suitably non-degenerate and arranged in such a way as to enable specific types of spatial, temporal, or spatiotemporal inferences. We present here an overview of the geometries accessible to the L1 constellation and timing-based and plasma-based observations of solar wind structures from 2016-17. We discuss the unique potential of the constellation approach for space physics and space weather forecasting at 1 AU. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110008571','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110008571">Solar Wind Strahl Observations and Their Implication to the Core-Halo Formation due to Scattering</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Vinas, Adolfo F. 2011-01-01 A study of the kinetic properties of the strahl electron velocity distribution functions (VDF?s) in the solar wind is presented. This study focuses on the mechanisms that control and regulate the electron VDF?s and the stability of the strahl electrons in the solar wind; mechanisms that are not yet well understood. Various parameters are investigated such as the strahl-electron density, temperature anisotropy, and electron heat-flux. These parameters are used to investigate the stability of the strahl population. The analysis check for whether the strahl electrons are constrained by some instability (e.g., the whistler or KAW instabilities), or are maintained by other types of processes. The electron heat-flux and temperature anisotropy are determined by modeling of the 3D-VDF?s from which the moments properties of the various populations are obtained. The results of this study have profound implication on the current hypothesis about the probable formation of the solar wind halo electrons produced from the scattering of the strahl population. This hypothesis is strengthened by direct observations of the strahl electrons being scattered into the core-halo in an isolated event. The observation implies that the scattering of the strahl is not a continuous process but occurs in bursts in regions where conditions for wave growth providing the scattering are optimum. Sometimes, observations indicate that the strahl component is anisotropic (Tper/Tpal approx. 2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism, however this condition is not always observed. The study is based on high time resolution data from the Cluster/PEACE electron spectrometer. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26PSL.492..222O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26PSL.492..222O">Were chondrites magnetized by the early solar wind?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Oran, Rona; Weiss, Benjamin P.; Cohen, Ofer 2018-06-01 Chondritic meteorites have been traditionally thought to be samples of undifferentiated bodies that never experienced large-scale melting. This view has been challenged by the existence of post-accretional, unidirectional natural remanent magnetization (NRM) in CV carbonaceous chondrites. The relatively young inferred NRM age [∼10 million years (My) after solar system formation] and long duration of NRM acquisition (1-106 y) have been interpreted as evidence that the magnetizing field was that of a core dynamo within the CV parent body. This would imply that CV chondrites represent the primitive crust of a partially differentiated body. However, an alternative hypothesis is that the NRM was imparted by the early solar wind. Here we demonstrate that the solar wind scenario is unlikely due to three main factors: 1) the magnitude of the early solar wind magnetic field is estimated to be <0.1 μT in the terrestrial planet-forming region, 2) the resistivity of chondritic bodies limits field amplification due to pile-up of the solar wind to less than a factor of 3.5 times that of the instantaneous solar wind field, and 3) the solar wind field likely changed over timescales orders of magnitude shorter than the timescale of NRM acquisition. Using analytical arguments, numerical simulations and astronomical observations of the present-day solar wind and magnetic fields of young stars, we show that the maximum mean field the ancient solar wind could have imparted on an undifferentiated CV parent body is <3.5 nT, which is 3-4 and 3 orders of magnitude weaker than the paleointensities recorded by the CV chondrites Allende and Kaba, respectively. Therefore, the solar wind is highly unlikely to be the source of the NRM in CV chondrites. Nevertheless, future high sensitivity paleomagnetic studies of rapidly-cooled meteorites with high magnetic recording fidelity could potentially trace the evolution of the solar wind field in time. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930033847&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D50%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930033847&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D50%26Ntt%3Dlazarus">Pc3 activity at low geomagnetic latitudes - A comparison with solar wind observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Villante, U.; Lepidi, S.; Vellante, M.; Lazarus, A. J.; Lepping, R. P. 1992-01-01 On an hourly time-scale the different roles of the solar wind and interplanetary magnetic field (IMF) parameters on ground micropulsation activity can be better investigated than at longer time-scales. A long-term comparison between ground measurements made at L'Aquila and IMP 8 observations confirms the solar wind speed as the key parameter for the onset of pulsations even at low latitudes, although additional control of the energy transfer from the interplanetary medium to the earth's magnetosphere is clearly exerted by the cone angle. Above about 20 mHz the frequency of pulsations is confirmed to be closely related to the IMF magnitude while, in agreement with model predictions, the IMF magnitude is related to the amplitude of the local fundamental resonant mode. We provide an interesting example in which high resolution measurements simultaneously obtained in the foreshock region and on the ground show that external transversal fluctuations do not penetrate deep into the low latitude magnetosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980210218','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980210218">Mapping the Solar Wind from its Source Region into the Outer Corona</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Esser, Ruth 1998-01-01 Knowledge of the radial variation of the plasma conditions in the coronal source region of the solar wind is essential to exploring coronal heating and solar wind acceleration mechanisms. The goal of the present proposal is to determine as many plasma parameters in that region as possible by coordinating different observational techniques, such as Interplanetary Scintillation Observations, spectral line intensity observations, polarization brightness measurements and X-ray observations. The inferred plasma parameters are then used to constrain solar wind models. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800016210&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800016210&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dwind%2Bmonitor">Solar wind and magnetosphere interactions</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Russell, C. T.; Allen, J. H.; Cauffman, D. P.; Feynman, J.; Greenstadt, E. W.; Holzer, R. E.; Kaye, S. M.; Slavin, J. A.; Manka, R. H.; Rostoker, G. 1979-01-01 The relationship between the magnetosphere and the solar wind is addressed. It is noted that this interface determines how much of the solar plasma and field energy is transferred to the Earth's environment, and that this coupling not only varies in time, responding to major solar disturbances, but also to small changes in solar wind conditions and interplanetary field directions. It is recommended that the conditions of the solar wind and interplanetary medium be continuously monitored, as well as the state of the magnetosphere. Other recommendations include further study of the geomagnetic tail, tests of Pc 3,4 magnetic pulsations as diagnostics of the solar wind, and tests of kilometric radiation as a remote monitor of the auroral electrojet. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1511245D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1511245D">Solar wind modulation of UK lightning</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Davis, Chris; Harrison, Giles; Lockwood, Mike; Owens, Mathew; Barnard, Luke 2013-04-01 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4308709','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4308709">Direct evidence for kinetic effects associated with solar wind reconnection</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Xu, Xiaojun; Wang, Yi; Wei, Fengsi; Feng, Xueshang; Deng, Xiaohua; Ma, Yonghui; Zhou, Meng; Pang, Ye; Wong, Hon-Cheng 2015-01-01 Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas. In-situ observations in the Earth's magnetosphere provide solid consistence with theoretical models on the point that kinetic effects are required in the collisionless reconnection. However, all the observations associated with solar wind reconnection have been analyzed in the context of magnetohydrodynamics (MHD) although a lot of solar wind reconnection exhausts have been reported. Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown. Here, by dual-spacecraft observations, we report a solar wind reconnection with clear Hall magnetic fields. Its corresponding Alfvenic electron outflow jet, derived from the decouple between ions and electrons, is identified, showing direct evidence for kinetic effects that dominate the collisionless reconnection. The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed. PMID:25628139 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914825O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914825O">Solar wind parameteres and disturbances in STEREO view</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Opitz, Andrea 2017-04-01 The twin STEREO spacecraft provided two vantage point solar wind observations between 2007 and 2014. Instrumentation of the STEREO A and B spacecraft is very nearly identical, hence their measurements are easily comparable. These measurements are visualised and treated with different methods in order to obtain a global view of the in-ecliptic background solar wind and the disturbances such as CIRs and CMEs. Comparison of the two datasets and exclusion of spatial effects provides information on the in-ecliptic solar wind structure in the inner heliosphere. These methods and results will be revised in this paper. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM11B2317B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM11B2317B">Dynamics of Magnetopause Reconnection in Response to Variable Solar Wind Conditions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Berchem, J.; Richard, R. L.; Escoubet, C. P.; Pitout, F. 2017-12-01 Quantifying the dynamics of magnetopause reconnection in response to variable solar wind driving is essential to advancing our predictive understanding of the interaction of the solar wind/IMF with the magnetosphere. To this end we have carried out numerical studies that combine global magnetohydrodynamic (MHD) and Large-Scale Kinetic (LSK) simulations to identify and understand the effects of solar wind/IMF variations. The use of the low dissipation, high resolution UCLA MHD code incorporating a non-linear local resistivity allows the representation of the global configuration of the dayside magnetosphere while the use of LSK ion test particle codes with distributed particle detectors allows us to compare the simulation results with spacecraft observations such as ion dispersion signatures observed by the Cluster spacecraft. We present the results of simulations that focus on the impacts of relatively simple solar wind discontinuities on the magnetopause and examine how the recent history of the interaction of the magnetospheric boundary with solar wind discontinuities can modify the dynamics of magnetopause reconnection in response to the solar wind input. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...829..117S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...829..117S">On Solar Wind Origin and Acceleration: Measurements from ACE</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Stakhiv, Mark; Lepri, Susan T.; Landi, Enrico; Tracy, Patrick; Zurbuchen, Thomas H. 2016-10-01 The origin and acceleration of the solar wind are still debated. In this paper, we search for signatures of the source region and acceleration mechanism of the solar wind in the plasma properties measured in situ by the Advanced Composition Explorer spacecraft. Using the elemental abundances as a proxy for the source region and the differential velocity and ion temperature ratios as a proxy for the acceleration mechanism, we are able to identify signatures pointing toward possible source regions and acceleration mechanisms. We find that the fast solar wind in the ecliptic plane is the same as that observed from the polar regions and is consistent with wave acceleration and coronal-hole origin. We also find that the slow wind is composed of two components: one similar to the fast solar wind (with slower velocity) and the other likely originating from closed magnetic loops. Both components of the slow solar wind show signatures of wave acceleration. From these findings, we draw a scenario that envisions two types of wind, with different source regions and release mechanisms, but the same wave acceleration mechanism. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1413179-wind-solar-resource-data-sets-wind-solar-resource-data-sets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1413179-wind-solar-resource-data-sets-wind-solar-resource-data-sets">Wind and solar resource data sets: Wind and solar resource data sets</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Clifton, Andrew; Hodge, Bri-Mathias; Draxl, Caroline The range of resource data sets spans from static cartography showing the mean annual wind speed or solar irradiance across a region to high temporal and high spatial resolution products that provide detailed information at a potential wind or solar energy facility. These data sets are used to support continental-scale, national, or regional renewable energy development; facilitate prospecting by developers; and enable grid integration studies. This review first provides an introduction to the wind and solar resource data sets, then provides an overview of the common methods used for their creation and validation. A brief history of wind and solarmore » resource data sets is then presented, followed by areas for future research.« less </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active">8</li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active">9</li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910043354&hterms=fisica&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dfisica','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910043354&hterms=fisica&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dfisica">A study of the relationship between micropulsations and solar wind properties</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Yedidia, B. A.; Lazarus, A. J.; Vellante, M.; Villante, U. 1991-01-01 A year-long comparison between daily averages of solar wind parameters obtained from the MIT experiment on IMP-8 and micropulsation measurements made by the Universita dell'Aquila has shown a correlation between solar wind speed and micropulsation power with peaks of the correlation coefficient greater than 0.8 in the period range from 20 to 40 s. Different behavior observed for different period bands suggests that the shorter period activity tends to precede the highest values of the solar wind speed while the longer period activity tends to persist for longer intervals within high velocity solar wind streams. A comparison with simultaneous interplanetary magnetic field measurements supports the upstream origin of the observed ground pulsations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018A%26A...612A..84D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018A%26A...612A..84D">Mapping the solar wind HI outflow velocity in the inner heliosphere by coronagraphic ultraviolet and visible-light observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dolei, S.; Susino, R.; Sasso, C.; Bemporad, A.; Andretta, V.; Spadaro, D.; Ventura, R.; Antonucci, E.; Abbo, L.; Da Deppo, V.; Fineschi, S.; Focardi, M.; Frassetto, F.; Giordano, S.; Landini, F.; Naletto, G.; Nicolini, G.; Nicolosi, P.; Pancrazzi, M.; Romoli, M.; Telloni, D. 2018-05-01 We investigated the capability of mapping the solar wind outflow velocity of neutral hydrogen atoms by using synergistic visible-light and ultraviolet observations. We used polarised brightness images acquired by the LASCO/SOHO and Mk3/MLSO coronagraphs, and synoptic Lyα line observations of the UVCS/SOHO spectrometer to obtain daily maps of solar wind H I outflow velocity between 1.5 and 4.0 R⊙ on the SOHO plane of the sky during a complete solar rotation (from 1997 June 1 to 1997 June 28). The 28-days data sequence allows us to construct coronal off-limb Carrington maps of the resulting velocities at different heliocentric distances to investigate the space and time evolution of the outflowing solar plasma. In addition, we performed a parameter space exploration in order to study the dependence of the derived outflow velocities on the physical quantities characterising the Lyα emitting process in the corona. Our results are important in anticipation of the future science with the Metis instrument, selected to be part of the Solar Orbiter scientific payload. It was conceived to carry out near-sun coronagraphy, performing for the first time simultaneous imaging in polarised visible-light and ultraviolet H I Lyα line, so providing an unprecedented view of the solar wind acceleration region in the inner corona. The movie (see Sect. 4.2) is available at https://www.aanda.org </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH23C2675C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH23C2675C">Intermittency Statistics in the Expanding Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cuesta, M. E.; Parashar, T. N.; Matthaeus, W. H. 2017-12-01 The solar wind is observed to be turbulent. One of the open questions in solar wind research is how the turbulence evolves as the solar wind expands to great distances. Some studies have focused on evolution of the outer scale but not much has been done to understand how intermittency evolves in the expanding wind beyond 1 AU (see [1,2]). We use magnetic field data from Voyager I spacecraft from 1 to 10AU to study the evolution of statistics of magnetic discontinuities. We perform various statistical tests on these discontinuities and make connections to the physical processes occurring in the expanding wind.[1] Tsurutani, Bruce T., and Edward J. Smith. "Interplanetary discontinuities: Temporal variations and the radial gradient from 1 to 8.5 AU." Journal of Geophysical Research: Space Physics 84.A6 (1979): 2773-2787.[2] Greco, A., et al. "Evidence for nonlinear development of magnetohydrodynamic scale intermittency in the inner heliosphere." The Astrophysical Journal 749.2 (2012): 105. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920041687&hterms=Bedini&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBedini','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920041687&hterms=Bedini&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBedini">The Solar Wind Ion Composition Spectrometer</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gloeckler, G.; Geiss, J.; Balsiger, H.; Bedini, P.; Cain, J. C.; Fisher, J.; Fisk, L. A.; Galvin, A. B.; Gliem, F.; Hamilton, D. C. 1992-01-01 The Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses is designed to determine uniquely the elemental and ionic-charge composition, and the temperatures and mean speeds of all major solar-wind ions, from H through Fe, at solar wind speeds ranging from 175 km/s (protons) to 1280 km/s (Fe(8+)). The instrument, which covers an energy per charge range from 0.16 to 59.6 keV/e in about 13 min, combines an electrostatic analyzer with postacceleration, followed by a time-of-flight and energy measurement. The measurements made by SWICS will have an impact on many areas of solar and heliospheric physics, in particular providing essential and unique information on: (1) conditions and processes in the region of the corona where the solar wind is accelerated; (2) the location of the source regions of the solar wind in the corona; (3) coronal heating processes; (4) the extent and causes of variations in the composition of the solar atmosphere; (5) plasma processes in the solar wind; (6) the acceleration of energetic particles in the solar wind; (7) the thermalization and acceleration of interstellar ions in the solar wind, and their composition; and (8) the composition, charge states, and behavior of the plasma in various regions of the Jovian magnetosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.9652R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.9652R">Comparison of solar wind driving of the aurora in the two hemispheres due to the solar wind dynamo</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Reistad, Jone Peter; Østgaard, Nikolai; Magnus Laundal, Karl; Haaland, Stein; Tenfjord, Paul; Oksavik, Kjellmar 2014-05-01 Event studies of simultaneous global imaging of the aurora in both hemispheres have suggested that an asymmetry of the solar wind driving between the two hemispheres could explain observations of non-conjugate aurora during specific driving conditions. North-South asymmetries in energy transfer from the solar wind across the magnetopause is believed to depend upon the dipole tilt angle and the x-component of the interplanetary magnetic field (IMF). Both negative tilt (winter North) and negative IMF Bx is expected to enhance the efficiency of the solar wind dynamo in the Northern Hemisphere. By the same token, positive tilt and IMF Bx is expected to enhance the solar wind dynamo efficiency in the Southern Hemisphere. We show a statistical study of the auroral response from both hemispheres using global imaging where we compare results during both favourable and not favourable conditions in each hemisphere. By this study we will address the question of general impact on auroral hemispheric asymmetries by this mechanism - the asymmetric solar wind dynamo. We use data from the Wideband Imaging Camera on the IMAGE spacecraft which during its lifetime from 2000-2005 covered both hemispheres. To ease comparison of the two hemispheres, seasonal differences in auroral brightness is removed as far as data coverage allows by only using events having small dipole tilt angles. Hence, the IMF Bx is expected to be the controlling parameter for the hemispheric preference of strongest solar wind dynamo efficiency in our dataset. Preliminary statistical results indicate the expected opposite behaviour in the two hemispheres, however, the effect is believed to be weak. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4394679','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4394679">Kinetic scale turbulence and dissipation in the solar wind: key observational results and future outlook</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Goldstein, M. L.; Wicks, R. T.; Perri, S.; Sahraoui, F. 2015-01-01 Turbulence is ubiquitous in the solar wind. Turbulence causes kinetic and magnetic energy to cascade to small scales where they are eventually dissipated, adding heat to the plasma. The details of how this occurs are not well understood. This article reviews the evidence for turbulent dissipation and examines various diagnostics for identifying solar wind regions where dissipation is occurring. We also discuss how future missions will further enhance our understanding of the importance of turbulence to solar wind dynamics. PMID:25848084 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4295037','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4295037">Solar origins of solar wind properties during the cycle 23 solar minimum and rising phase of cycle 24</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Luhmann, Janet G.; Petrie, Gordon; Riley, Pete 2012-01-01 The solar wind was originally envisioned using a simple dipolar corona/polar coronal hole sources picture, but modern observations and models, together with the recent unusual solar cycle minimum, have demonstrated the limitations of this picture. The solar surface fields in both polar and low-to-mid-latitude active region zones routinely produce coronal magnetic fields and related solar wind sources much more complex than a dipole. This makes low-to-mid latitude coronal holes and their associated streamer boundaries major contributors to what is observed in the ecliptic and affects the Earth. In this paper we use magnetogram-based coronal field models to describe the conditions that prevailed in the corona from the decline of cycle 23 into the rising phase of cycle 24. The results emphasize the need for adopting new views of what is ‘typical’ solar wind, even when the Sun is relatively inactive. PMID:25685422 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140002234','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140002234">Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris 2013-01-01 A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhDT........77L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhDT........77L">The structure of the solar wind in the inner heliosphere</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lee, Christina On-Yee 2010-12-01 This dissertation is devoted to expanding our understanding of the solar wind structure in the inner heliosphere and variations therein with solar activity. Using spacecraft observations and numerical models, the origins of the large-scale structures and long-term trends of the solar wind are explored in order to gain insights on how our Sun determines the space environments of the terrestrial planets. I use long term measurements of the solar wind density, velocity, interplanetary magnetic field, and particles, together with models based on solar magnetic field data, to generate time series of these properties that span one solar rotation (˜27 days). From these time series, I assemble and obtain the synoptic overviews of the solar wind properties. The resulting synoptic overviews show that the solar wind around Mercury, Venus, Earth, and Mars is a complex co-rotating structure with recurring features and occasional transients. During quiet solar conditions, the heliospheric current sheet, which separates the positive interplanetary magnetic field from the negative, usually has a remarkably steady two- or four-sector structure that persists for many solar rotations. Within the sector boundaries are the slow and fast speed solar wind streams that originate from the open coronal magnetic field sources that map to the ecliptic. At the sector boundaries, compressed high-density and the related high-dynamic pressure ridges form where streams from different coronal source regions interact. High fluxes of energetic particles also occur at the boundaries, and are seen most prominently during the quiet solar period. The existence of these recurring features depends on how long-lived are their source regions. In the last decade, 3D numerical solar wind models have become more widely available. They provide important scientific tools for obtaining a more global view of the inner heliosphere and of the relationships between conditions at Mercury, Venus, Earth, and Mars. When </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20120011917&hterms=WIND+STORMS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWIND%2BSTORMS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20120011917&hterms=WIND+STORMS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWIND%2BSTORMS">Solar Wind Charge Exchange During Geomagnetic Storms</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D. 2012-01-01 On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070011399&hterms=lazarus&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070011399&hterms=lazarus&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlazarus">Solar Wind Helium Abundance as a Function of Speed and Heliographic Latitude: Variation through a Solar Cycle</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kasper, J. C.; Stenens, M. L.; Stevens, M. L.; Lazarus, A. J.; Steinberg, J. T.; Ogilvie, Keith W. 2006-01-01 We present a study of the variation of the relative abundance of helium to hydrogen in the solar wind as a function of solar wind speed and heliographic latitude over the previous solar 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 Wind spacecraft between 1995 and 2005. The higher speed and time resolution of this study compared to an earlier work with the Wind observations has led to the discovery of three new aspects of A(sub He), modulation during solar minimum from mid-1995 to mid-1997. First, we find that for solar wind 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 wind 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 solar wind 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 solar wind 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 solar maximum the A(sub He), dependences on speed and latitude disappear, and we interpret this as evidence of two source regions for slow solar wind in the ecliptic plane, one being the solar minimum streamer belt and the other likely being active regions. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSH43C1975L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSH43C1975L">Are current sheets the boundary of fluxtubes in the solar wind? -- A study from multiple spacecraft observation</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Li, G.; Arnold, L.; Miao, B.; Yan, Y. 2011-12-01 G. Li (1,2), L. Arnold (1), B. Miao (3) and Y. Yan (4) (1) Department of Physics, University of Alabama in Huntsville Huntsville, AL, 35899 (2) CSPAR, University of Alabama in Huntsville Huntsville, AL, 35899 (3) School of Earth and Space Sciences, University of Science and Technology of CHINA, Hefei, China (4) Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China Current sheets is a common structure in the solar wind and is a significant source of solar wind MHD turbulence intermittency. The origin of these structure is presently unknown. Non-linear interactions of the solar wind MHD turbulence can spontaneously generate these structures. On the other hand, there are proposals that these structures may represent relic structures having solar origins. Using a technique developed in [1], we examine current sheets in the solar wind from multiple spacecraft. We identify the "single-peak" and "double-peak" events in the solar wind and discuss possible scenarios for these events and its implication of the origin of the current sheets. [1] Li, G., "Identify current-sheet-like structures in the solar wind", ApJL 672, L65, 2008. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH21C..08W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH21C..08W">Does the magnetic expansion factor play a role in solar wind acceleration?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wallace, S.; Arge, C. N.; Pihlstrom, Y. 2017-12-01 For the past 25+ years, the magnetic expansion factor (fs) has been a parameter used in the calculation of terminal solar wind speed (vsw) in the Wang-Sheeley-Arge (WSA) coronal and solar wind model. The magnetic expansion factor measures the rate of flux tube expansion in cross section between the photosphere out to 2.5 solar radii (i.e., source surface), and is inversely related to vsw (Wang & Sheeley, 1990). Since the discovery of this inverse relationship, the physical role that fs plays in solar wind acceleration has been debated. In this study, we investigate whether fs plays a causal role in determining terminal solar wind speed or merely serves as proxy. To do so, we study pseudostreamers, which occur when coronal holes of the same polarity are near enough to one another to limit field line expansion. Pseudostreamers are of particular interest because despite having low fs, spacecraft observations show that solar wind emerging from these regions have slow to intermediate speeds of 350-550 km/s (Wang et al., 2012). In this work, we develop a methodology to identify pseudostreamers that are magnetically connected to satellites using WSA output produced with ADAPT input maps. We utilize this methodology to obtain the spacecraft-observed solar wind speed from the exact parcel of solar wind that left the pseudostreamer. We then compare the pseudostreamer's magnetic expansion factor with the observed solar wind speed from multiple spacecraft (i.e., ACE, STEREO-A & B, Ulysses) magnetically connected to the region. We will use this methodology to identify several cases ( 20) where spacecraft are magnetically connected to pseudostreamers, and perform a statistical analysis to determine the correlation of fs within pseudostreamers and the terminal speed of the solar wind emerging from them. This work will help determine if fs plays a physical role in the speed of solar wind originating from regions that typically produce slow wind. This work compliments previous case </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...804L..41T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...804L..41T">Inertial Range Turbulence of Fast and Slow Solar Wind at 0.72 AU and Solar Minimum</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Teodorescu, Eliza; Echim, Marius; Munteanu, Costel; Zhang, Tielong; Bruno, Roberto; Kovacs, Peter 2015-05-01 We investigate Venus Express observations of magnetic field fluctuations performed systematically in the solar wind at 0.72 Astronomical Units (AU), between 2007 and 2009, during the deep minimum of solar cycle 24. The power spectral densities (PSDs) of the magnetic field components have been computed for time intervals that satisfy the data integrity criteria and have been grouped according to the type of wind, fast and slow, defined for speeds larger and smaller, respectively, than 450 km s-1. The PSDs show higher levels of power for the fast wind than for the slow. The spectral slopes estimated for all PSDs in the frequency range 0.005-0.1 Hz exhibit a normal distribution. The average value of the trace of the spectral matrix is -1.60 for fast solar wind and -1.65 for slow wind. Compared to the corresponding average slopes at 1 AU, the PSDs are shallower at 0.72 AU for slow wind conditions suggesting a steepening of the solar wind spectra between Venus and Earth. No significant time variation trend is observed for the spectral behavior of both the slow and fast wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25848084','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25848084">Kinetic scale turbulence and dissipation in the solar wind: key observational results and future outlook.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Goldstein, M L; Wicks, R T; Perri, S; Sahraoui, F 2015-05-13 Turbulence is ubiquitous in the solar wind. Turbulence causes kinetic and magnetic energy to cascade to small scales where they are eventually dissipated, adding heat to the plasma. The details of how this occurs are not well understood. This article reviews the evidence for turbulent dissipation and examines various diagnostics for identifying solar wind regions where dissipation is occurring. We also discuss how future missions will further enhance our understanding of the importance of turbulence to solar wind dynamics. © 2015 The Author(s) Published by the Royal Society. All rights reserved. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840005034','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840005034">Interplanetary scintillation observations of the solar wind close to the Sun and out of the ecliptic</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sime, D. G. 1983-01-01 A brief review is given of recent developments in the observation of the solar wind by the method of interplanetary scintillation. The emphasis is on observations of the velocity structure, the electron density and the effect of propagating disturbances in the interplanetary medium as detected principally by intensity and phase scintillation and by spectral broadening. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850032849&hterms=ici&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dici','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850032849&hterms=ici&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dici">Interpretation of He-3 abundance variations in the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Coplan, M. A.; Ogilvie, K. W.; Bochsler, P.; Geiss, J. 1984-01-01 The ion composition instrument (ICI) on ISEE-3 observed the isotopes of helium of mass 3 and 4 in the solar wind almost continuously between August 1978 and July 1982. This period included the increase towards the maximum of solar activity cycle 21, the maximum period, and the beginning of the descent towards solar minimum. Observations were made when the solar wind speed was between 300 and 620 km/s. For part of the period evidence for regular interplanetary magnetic sector structure was clear and a number of He-3 flares occurred during this time. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22518620-reconstructing-solar-wind-from-its-early-history-current-epoch','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22518620-reconstructing-solar-wind-from-its-early-history-current-epoch">RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Airapetian, Vladimir S.; Usmanov, Arcadi V., E-mail: vladimir.airapetian@nasa.gov, E-mail: avusmanov@gmail.com Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electronmore » temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH11B2444S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH11B2444S">Kinetic-Scale Electric and Magnetic Field Fluctuations in the Solar Wind at 1 AU: THEMIS/ARTEMIS Observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Salem, C. S.; Hanson, E.; Bonnell, J. W.; Chaston, C. C.; Bale, S. D.; Mozer, F. 2017-12-01 We present here an analysis of kinetic-scale electromagnetic fluctuations in the solar wind using data from THEMIS and ARTEMIS spacecraft. We use high-time resolution electric and magnetic field measurements, as well as density fluctuations, up to 128 samples per second, as well as particle burst plasma data during carefully selected solar wind intervals. We focus our analysis on a few such intervals spanning different values of plasma beta and angles between the local magnetic field and the radial Sun-Earth direction. We discuss the careful analysis process of characterizing and removing the different instrumental effects and noise sources affecting the electric and magnetic field data at those scales, above 0.1 Hz or so, above the breakpoint marking the start of the so-called dissipation range of solar wind turbulence. We compute parameters such as the electric to magnetic field ratio, the magnetic compressibility, magnetic helicity, and other relevant quantities in order to diagnose the nature of the fluctuations at those scales between the ion and electron cyclotron frequencies, extracting information on the dominant modes composing the fluctuations. We also discuss the presence and role of coherent structures in the measured fluctuations. The nature of the fluctuations in the dissipation or dispersive scales of solar wind turbulence is still debated. This observational study is also highly relevant to the current Turbulent Dissipation Challenge. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28139769','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28139769">Global solar wind variations over the last four centuries.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Owens, M J; Lockwood, M; Riley, P 2017-01-31 The most recent "grand minimum" of solar activity, the Maunder minimum (MM, 1650-1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth's magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active">9</li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active">10</li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5282500','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5282500">Global solar wind variations over the last four centuries</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Owens, M. J.; Lockwood, M.; Riley, P. 2017-01-01 The most recent “grand minimum” of solar activity, the Maunder minimum (MM, 1650–1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth’s magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima. PMID:28139769 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667380-solar-wind-origin-acceleration-measurements-from-ace','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667380-solar-wind-origin-acceleration-measurements-from-ace">ON SOLAR WIND ORIGIN AND ACCELERATION: MEASUREMENTS FROM ACE</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Stakhiv, Mark; Lepri, Susan T.; Landi, Enrico The origin and acceleration of the solar wind are still debated. In this paper, we search for signatures of the source region and acceleration mechanism of the solar wind in the plasma properties measured in situ by the Advanced Composition Explorer spacecraft. Using the elemental abundances as a proxy for the source region and the differential velocity and ion temperature ratios as a proxy for the acceleration mechanism, we are able to identify signatures pointing toward possible source regions and acceleration mechanisms. We find that the fast solar wind in the ecliptic plane is the same as that observed frommore » the polar regions and is consistent with wave acceleration and coronal-hole origin. We also find that the slow wind is composed of two components: one similar to the fast solar wind (with slower velocity) and the other likely originating from closed magnetic loops. Both components of the slow solar wind show signatures of wave acceleration. From these findings, we draw a scenario that envisions two types of wind, with different source regions and release mechanisms, but the same wave acceleration mechanism.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040047164&hterms=topology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtopology','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040047164&hterms=topology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtopology">Coronal Magnetic Field Topology and Source of Fast Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Guhathakurta, M.; Sittler, E.; Fisher, R.; McComas, D.; Thompson, B. 1999-01-01 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/978002','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/978002">The Genesis Mission: Solar Wind Conditions, and Implications for the FIP Fractionation of the Solar Wind.</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Reisenfeld, D. B.; Wiens, R. C.; Barraclough, B. L. 2005-01-01 The NASA Genesis mission collected solar wind on ultrapure materials between November 30, 2001 and April 1, 2004. The samples were returned to Earth September 8, 2004. Despite the hard landing that resulted from a failure of the avionics to deploy the parachute, many samples were returned in a condition that will permit analyses. Sample analyses of these samples should give a far better understanding of the solar elemental and isotopic composition (Burnett et al. 2003). Further, the photospheric composition is thought to be representative of the solar nebula, so that the Genesis mission will provide a new baseline formore » the average solar nebula composition with which to compare present-day compositions of planets, meteorites, and asteroids. Sample analysis is currently underway. The Genesis samples must be placed in the context of the solar and solar wind conditions under which they were collected. Solar wind is fractionated from the photosphere by the forces that accelerate the ions off of the Sun. This fractionation appears to be ordered by the first ionization potential (FIP) of the elements, with the tendency for low-FIP elements to be over-abundant in the solar wind relative to the photosphere, and high-FIP elements to be under-abundant (e.g. Geiss, 1982; von Steiger et al., 2000). In addition, the extent of elemental fractionation differs across different solarwind regimes. Therefore, Genesis collected solar wind samples sorted into three regimes: 'fast wind' or 'coronal hole' (CH), 'slow wind' or 'interstream' (IS), and 'coronal mass ejection' (CME). To carry this out, plasma ion and electron spectrometers (Barraclough et al., 2003) continuously monitored the solar wind proton density, velocity, temperature, the alpha/proton ratio, and angular distribution of suprathermal electrons, and those parameters were in turn used in a rule-based algorithm that assigned the most probable solar wind regime (Neugebauer et al., 2003). At any given time, only one of </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021285&hterms=kellogg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dkellogg','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021285&hterms=kellogg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dkellogg">Some remarks on waves in the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kellogg, Paul J. 1995-01-01 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 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950037048&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950037048&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3Dlazarus">Voyager observations of O(+6) and other minor ions in the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Villanueva, Louis; Mcnutt, Ralph L., Jr.; Lazarus, Alan J.; Steinberg, John T. 1994-01-01 The plasma science (PLS) experiments on the Voyager 1 and 2 spacecraft began making measurements of the solar wind shortly after the two launches in the fall of 1977. In reviewing the data obtained prior to the Jupiter encounters in 1979, we have found that the large dynamic range of the PLS instrument generally allows a clean separation of signatures of minor ions (about 2.5% of the time) during a single instrument scan in energy per charge. The minor ions, most notably O(+6), are well separated from the protons and alpha particles during times when the solar wind Mach number (ratio of streaming speed to thermal speed) is greater than approximately 15. During the Earth to Jupiter cruise we find that the average ratio of alpha particle number density to that of oxygen is 66 +/- 7 (Voyager 1) and 71 +/- 17 (Voyager 2). These values are consistent with the value 75 +/- 20 inferred from the Ion Composition Instrument on ISEE 3 during the period spanning 1978 and 1982. We have inferred an average coronal temperature of (1.7 +/- 0.1) x 10(exp 6) K based on the ratio of O(+7) to O(+6) number densities. Our observations cover a period of increasing solar activity. During this time we have found that the alpha particle to proton number density ratio is increasing with the solar cycle, the oxygen to proton ratio increases, and the alpha particle to oxygen ratio remains relatively constant in time. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080030140&hterms=puzzle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpuzzle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080030140&hterms=puzzle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpuzzle">Magnetofluid Turbulence in the Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Goldstein, Melvyn L. 2008-01-01 The solar wind shows striking characteristics that suggest that it is a turbulent magnetofluid, but the picture is not altogether simple. From the earliest observations, a strong correlation between magnetic fluctuations and plasma velocity fluctuations was noted. The high corrections suggest that the fluctuations are Alfven waves. In addition, the power spectrum of the magnetic fluctuation showed evidence of an inertial range that resembled that seen in fully-developed fluid turbulence. Alfven waves, however, are exact solutions of the equations of incompressible magnetohydrodynamics. Thus, there was a puzzle: how can a magnetofluid consisting of Alfven waves be turbulent? The answer lay in the role of velocity shears in the solar wind that could drive turbulent evolution. Puzzles remain: for example, the power spectrum of the velocity fluctuations is less steep than the slope of the magnetic fluctuations, nor do we understand even now why the solar wind appears to be nearly incompressible with a -5/3 power-spectral index. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSH11A1502A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSH11A1502A">Implications of the Deep Minimum for Slow Solar Wind Origin</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Antiochos, S. K.; Mikic, Z.; Lionello, R.; Titov, V. S.; Linker, J. A. 2009-12-01 The origin of the slow solar wind has long been one of the most important problems in solar/heliospheric physics. Two observational constraints make this problem especially challenging. First, the slow wind has the composition of the closed-field corona, unlike the fast wind that originates on open field lines. Second, the slow wind has substantial angular extent, of order 30 degrees, which is much larger than the widths observed for streamer stalks or the widths expected theoretically for a dynamic heliospheric current sheet. We propose that the slow wind originates from an intricate network of narrow (possibly singular) open-field corridors that emanate from the polar coronal hole regions. Using topological arguments, we show that these corridors must be ubiquitous in the solar corona. The total solar eclipse in August 2008, near the lowest point of the Deep Minimum, affords an ideal opportunity to test this theory by using the ultra-high resolution Predictive Science's (PSI) eclipse model for the corona and wind. Analysis of the PSI eclipse model demonstrates that the extent and scales of the open-field corridors can account for both the angular width of the slow wind and its closed-field composition. We discuss the implications of our slow wind theory for the structure of the corona and heliosphere at the Deep Minimum and describe further observational and theoretical tests. This work has been supported by the NASA HTP, SR&T, and LWS programs. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950029599&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D50%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950029599&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D50%26Ntt%3Dlazarus">Solar wind velocity and temperature in the outer heliosphere</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J. 1994-01-01 At the end of 1992, the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were at heliocentric distances of 56.0, 37.3, and 39.0 AU and heliographic latitudes of 3.3 deg N, 17.4 deg N, and 8.6 deg S, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer 10 is on the opposite side of the Sun. All three spacecraft have working plasma analyzers, so intercomparison of data from these spacecraft provides important information about the global character of the solar wind in the outer heliosphere. The averaged solar wind speed continued to exhibit its well-known variation with solar cycle: Even at heliocentric distances greater than 50 AU, the average speed is highest during the declining phase of the solar cycle and lowest near solar minimum. There was a strong latitudinal gradient in solar wind speed between 3 deg and 17 deg N during the last solar minimum, but this gradient has since disappeared. The solar wind temperature declined with increasing heliocentric distance out to a heliocentric distance of at least 20 AU; this decline appeared to continue at larger heliocentric distances, but temperatures in the outer heliosphere were suprisingly high. While Pioneer 10 and Voyager 2 observed comparable solar wind temperatures, the temperature at Pioneer 11 was significantly higher, which suggests the existence of a large-scale variation of temperature with heliographic longitude. There was also some suggestion that solar wind temperatures were higher near solar minimum. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930049596&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dbackground%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930049596&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dbackground%2Bwind">Evolution of spatial and temporal correlations in the solar wind - Observations and interpretation</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Klein, L. W.; Matthaeus, W. H.; Roberts, D. A.; Goldstein, M. L. 1992-01-01 Observations of solar wind magnetic field spectra from 1-22 AU indicate a distinctive structure in frequency which evolves with increasing heliocentric distance. At 1 AU extremely low frequency correlations are associated with temporal variations at the solar period and its first few harmonics. For periods of l2-96 hours, a l/f distribution is observed, which we interpret as an aggregate of uncorrelated coronal structures which have not dynamically interacted by 1 AU. At higher frequencies the familiar Kolmogorov-like power law is seen. Farther from the sun the frequency break point between the shallow l/f and the steeper Kolmogorov spectrum evolves systematically towards lower frequencies. We suggest that the Kolmogorov-like spectra emerge due to in situ turbulence that generates spatial correlations associated with the turbulent cascade and that the background l/f noise is a largely temporal phenomenon, not associated with in situ dynamical processes. In this paper we discuss these ideas from the standpoint of observations from several interplanetary spacecraft. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH33B2774N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH33B2774N">Heating of Solar Wind Ions via Cyclotron Resonance</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Navarro, R.; Moya, P. S.; Figueroa-Vinas, A.; Munoz, V.; Valdivia, J. A. 2017-12-01 Remote and in situ observations in the solar wind show that ion and electron velocity distributions persistently deviate from thermal equilibrium in the form of relative streaming between species components, temperature anisotropy, etc. These non-thermal features represent a source of free energy for the excitation of kinetic instabilities and fluctuations in the plasma. In this regard, it is believed that plasma particles can be heated, through a second order Fermi acceleration process, by multiple resonances with unstable counter-propagating field-aligned Ion-cyclotron waves. For multi-species plasmas, several collective wave modes participate in this process. In this work, we test this model by studying the percentage of ions that resonate with the waves modes described by the proper kinetic multi-species dispersion relation in a solar-wind-like plasma composed of electrons, protons, and alpha particles. Numerical results are compared with WIND spacecraft data to test its relevance for the existence of thresholds for the preferential perpendicular heating of He+2 ions as observed in the solar wind fast streams. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH22B..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH22B..03H">IPS analysis on relationship among velocity, density and temperature of the solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hayashi, K.; Tokumaru, M.; Fujiki, K. 2015-12-01 The IPS(Interplanetary Scintillation)-MHD(magnetohydrodynamics) tomography is a method we have developed to determine three-dimensional MHD solution of the solar wind that best matches the line-of-sight IPS solar-wind speed data (Hayashi et al., 2003). The tomographic approach is an iteration method in which IPS observations are simulated in MHD steady-state solution, then differences between the simulated observation and the actual IPS observation is reduced by modifying solar-wind boundary map at 50 solar radii. This forward model needs to assume solar wind density and temperature as function of speed. We use empirical functions, N(V) and T(V), derived from Helios in-situ measurement data within 0.5 AU in 1970s. For recent years, especially after 2006, these functions yield higher densities and lower temperatures than in-situ measurements indicate. To characterize the differences between the simulated and actual solar wind plasma, we tune parameters in the functions so that agreements with in-situ data (near the Earth and at Ulysses) will be optimized. This optimization approach can help better simulations of the solar corona and heliosphere, and will help our understandings on roles of magnetic field in solar wind heating and acceleration. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140002249','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140002249">Global Network of Slow Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Crooker, N. U.; Antiochos, S. K.; Zhao, X.; Neugebauer, M. 2012-01-01 The streamer belt region surrounding the heliospheric current sheet (HCS) is generally treated as the primary or sole source of the slow solar wind. Synoptic maps of solar wind speed predicted by the Wang-Sheeley-Arge model during selected periods of solar cycle 23, however, show many areas of slow wind displaced from the streamer belt. These areas commonly have the form of an arc that is connected to the streamer belt at both ends. The arcs mark the boundaries between fields emanating from different coronal holes of the same polarity and thus trace the paths of belts of pseudostreamers, i.e., unipolar streamers that form over double arcades and lack current sheets. The arc pattern is consistent with the predicted topological mapping of the narrow open corridor or singular separator line that must connect the holes and, thus, consistent with the separatrix-web model of the slow solar wind. Near solar maximum, pseudostreamer belts stray far from the HCS-associated streamer belt and, together with it, form a global-wide web of slow wind. Recognition of pseudostreamer belts as prominent sources of slow wind provides a new template for understanding solar wind stream structure, especially near solar maximum. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRA..113.8107Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRA..113.8107Z">Statistical validation of a solar wind propagation model from 1 to 10 AU</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zieger, Bertalan; Hansen, Kenneth C. 2008-08-01 A one-dimensional (1-D) numerical magnetohydrodynamic (MHD) code is applied to propagate the solar wind from 1 AU through 10 AU, i.e., beyond the heliocentric distance of Saturn's orbit, in a non-rotating frame of reference. The time-varying boundary conditions at 1 AU are obtained from hourly solar wind data observed near the Earth. Although similar MHD simulations have been carried out and used by several authors, very little work has been done to validate the statistical accuracy of such solar wind predictions. In this paper, we present an extensive analysis of the prediction efficiency, using 12 selected years of solar wind data from the major heliospheric missions Pioneer, Voyager, and Ulysses. We map the numerical solution to each spacecraft in space and time, and validate the simulation, comparing the propagated solar wind parameters with in-situ observations. We do not restrict our statistical analysis to the times of spacecraft alignment, as most of the earlier case studies do. Our superposed epoch analysis suggests that the prediction efficiency is significantly higher during periods with high recurrence index of solar wind speed, typically in the late declining phase of the solar cycle. Among the solar wind variables, the solar wind speed can be predicted to the highest accuracy, with a linear correlation of 0.75 on average close to the time of opposition. We estimate the accuracy of shock arrival times to be as high as 10-15 hours within ±75 d from apparent opposition during years with high recurrence index. During solar activity maximum, there is a clear bias for the model to predicted shocks arriving later than observed in the data, suggesting that during these periods, there is an additional acceleration mechanism in the solar wind that is not included in the model. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021473&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021473&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bintensity%2Bmeasurement">Comparison between solar wind latitude distribution derived from Lyman-alpha observations and Ulysses measurements</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Quemarais, E.; Lallement, R.; Bertaux, J. L.; Sandel, B. R. 1995-01-01 The all-sky interplanetary Lyman-alpha pattern is sensitive to the latitude distribution of the solar wind because of destruction of neutral H by charge-exchange with solar wind protons. Lyman-alpha intensities recorded by Prognoz 5 and 6 in 1976 in a few parts of the sky were demonstrating a decrease of solar wind mass flux by about 30 % from equator to pole, when assuming a sinusoidal variation of this mass flux (harmonic distribution). A new analysis with a discrete variation with latitude has shown a decrease from 0 to 30 deg and then a plateau of constant mass flux up to the pole. This distribution bears a striking resemblance with Ulysses in-situ measurements, showing a clear similarity at 19 years interval. The Ulysses measurements were then used as a model input to calculate an all-sky Lyman-alpha pattern, either with a discrete model or with a harmonic solar wind variation with the same Ulysses equator-to-pole variation. There are conspicuous differences between the two Lyman-alpha patterns, in particular in the downwind region which are discussed in the context of future all-sky measurements with SWAN experiment on SOHO. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810025913&hterms=debye+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddebye%2Blength','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810025913&hterms=debye+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddebye%2Blength">A comparison of solar wind and ionospheric ion acoustic waves</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kintner, P. M.; Kelley, M. C. 1980-01-01 Ion acoustic waves produced during the Trigger experiment are compared to ion acoustic waves observed in the solar wind. After normalizing to the Debye length the spectra are nearly identical, although the ionospheric wave relative energy density is 100 times larger than the solar wind case. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SpWea..15.1490L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SpWea..15.1490L">Data Assimilation in the Solar Wind: Challenges and First Results</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lang, Matthew; Browne, Philip; van Leeuwen, Peter Jan; Owens, Mathew 2017-11-01 Data assimilation (DA) is used extensively in numerical weather prediction (NWP) to improve forecast skill. Indeed, improvements in forecast skill in NWP models over the past 30 years have directly coincided with improvements in DA schemes. At present, due to data availability and technical challenges, DA is underused in space weather applications, particularly for solar wind prediction. This paper investigates the potential of advanced DA methods currently used in operational NWP centers to improve solar wind prediction. To develop the technical capability, as well as quantify the potential benefit, twin experiments are conducted to assess the performance of the Local Ensemble Transform Kalman Filter (LETKF) in the solar wind model ENLIL. Boundary conditions are provided by the Wang-Sheeley-Arge coronal model and synthetic observations of density, temperature, and momentum generated every 4.5 h at 0.6 AU. While in situ spacecraft observations are unlikely to be routinely available at 0.6 AU, these techniques can be applied to remote sensing of the solar wind, such as with Heliospheric Imagers or interplanetary scintillation. The LETKF can be seen to improve the state at the observation location and advect that improvement toward the Earth, leading to an improvement in forecast skill in near-Earth space for both the observed and unobserved variables. However, sharp gradients caused by the analysis of a single observation in space resulted in artificial wavelike structures being advected toward Earth. This paper is the first attempt to apply DA to solar wind prediction and provides the first in-depth analysis of the challenges and potential solutions. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830025552','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830025552">Solar wind iron abundance variations at solar wind speeds up to 600 km s sup -1, 1972 to 1976</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Mitchell, D. G.; Roelof, E. C.; Bame, S. J. 1982-01-01 The Fe/H ratios in the peaks of high speed streams (HSS) were analyzed during the decline of Solar Cycle 20 and the following minimum (October 1972 to December 1976). The response of the 50 to 200 keV ion channel of the APL/JHU energetic particle experiment (EPE) on IMP-7 and 8 was utilized to solar wind iron ions at high solar wind speeds (V or = 600 km/sec). Fe measurements with solar wind H and He parameters were compared 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 0.00001, abundance variations of a factor of up to 6 are obtained across a given coronal-hole associated HSS. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM23B..07E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM23B..07E">Soft X-ray study of solar wind charge exchange from the Earth's magnetosphere : Suzaku observations and a future X-ray imaging mission concept</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ezoe, Y.; Ishisaki, Y.; Ohashi, T.; Ishikawa, K.; Miyoshi, Y.; Fujimoto, R.; Terada, N.; Kasahara, S.; Fujimoto, M.; Mitsuda, K.; Nishijo, K.; Noda, A. 2013-12-01 Soft X-ray observations of solar wind charge exchange (SWCX) emission from the Earth's magnetosphere using the Japanese X-ray astronomy satellite Suzaku are shown, together with our X-ray imaging mission concept to characterize the solar wind interaction with the magnetosphere. In recent years, the SWCX emission from the Earth's magnetosphere, originally discovered as unexplained noise during the soft X-ray all sky survey (Snowden et al. 1994), is receiving increased attention on studying geospace. The SWCX is a reaction between neutrals in exosphere and highly charged ions in the magnetosphere originated from solar wind. Robertson et al. (2005) modeled the SWCX emission as seen from an observation point 50 Re from Earth. In the resulting X-ray intensities, the magnetopause, bow shock and cusp were clearly visible. High sensitivity soft X-ray observation with CCDs onboard recent X-ray astronomy satellites enables us to resolve SWCX emission lines and investigate time correlation with solar wind as observed with ACE and WIND more accurately. Suzaku is the 5th Japanese X-ray astronomy satellite launched in 2005. The line of sight direction through cusp is observable, while constraints on Earth limb avoidance angle of other satellites often limits observable regions. Suzaku firstly detected the SWCX emission while pointing in the direction of the north ecliptic pole (Fujimoto et al. 2007). Using the Tsyganenko 1996 magnetic field model, the distance to the nearest SWCX region was estimated as 2-8 Re, implying that the line of sight direction can be through magnetospheric cusp. Ezoe et al. (2010) reported SWCX events toward the sub-solar side of the magnetosheath. These cusp and sub-solar side magnetosheath regions are predicted to show high SWCX fluxes by Robertson et al. (2005). On the other hand, Ishikawa et al. (2013) discovered a similarly strong SWCX event when the line of sight direction did not transverse these two regions. Motivated by these detections </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910030156&hterms=Increased+entropy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DIncreased%2Bentropy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910030156&hterms=Increased+entropy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DIncreased%2Bentropy">Shock heating of the solar wind plasma</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Whang, Y. C.; Liu, Shaoliang; Burlaga, L. F. 1990-01-01 The role played by shocks in heating solar-wind plasma is investigated using data on 413 shocks which were identified from the plasma and magnetic-field data collected between 1973 and 1982 by Pioneer and Voyager spacecraft. It is found that the average shock strength increased with the heliocentric distance outside 1 AU, reaching a maximum near 5 AU, after which the shock strength decreased with the distance; the entropy of the solar wind protons also reached a maximum at 5 AU. An MHD simulation model in which shock heating is the only heating mechanism available was used to calculate the entropy changes for the November 1977 event. The calculated entropy agreed well with the value calculated from observational data, suggesting that shocks are chiefly responsible for heating solar wind plasma between 1 and 15 AU. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active">10</li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active">11</li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SSRv..204..131K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SSRv..204..131K">Solar Wind Electrons Alphas and Protons (SWEAP) Investigation: Design of the Solar Wind and Coronal Plasma Instrument Suite for Solar Probe Plus</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kasper, Justin C.; Abiad, Robert; Austin, Gerry; Balat-Pichelin, Marianne; Bale, Stuart D.; Belcher, John W.; Berg, Peter; Bergner, Henry; Berthomier, Matthieu; Bookbinder, Jay; Brodu, Etienne; Caldwell, David; Case, Anthony W.; Chandran, Benjamin D. G.; Cheimets, Peter; Cirtain, Jonathan W.; Cranmer, Steven R.; Curtis, David W.; Daigneau, Peter; Dalton, Greg; Dasgupta, Brahmananda; DeTomaso, David; Diaz-Aguado, Millan; Djordjevic, Blagoje; Donaskowski, Bill; Effinger, Michael; Florinski, Vladimir; Fox, Nichola; Freeman, Mark; Gallagher, Dennis; Gary, S. Peter; Gauron, Tom; Gates, Richard; Goldstein, Melvin; Golub, Leon; Gordon, Dorothy A.; Gurnee, Reid; Guth, Giora; Halekas, Jasper; Hatch, Ken; Heerikuisen, Jacob; Ho, George; Hu, Qiang; Johnson, Greg; Jordan, Steven P.; Korreck, Kelly E.; Larson, Davin; Lazarus, Alan J.; Li, Gang; Livi, Roberto; Ludlam, Michael; Maksimovic, Milan; McFadden, James P.; Marchant, William; Maruca, Bennet A.; McComas, David J.; Messina, Luciana; Mercer, Tony; Park, Sang; Peddie, Andrew M.; Pogorelov, Nikolai; Reinhart, Matthew J.; Richardson, John D.; Robinson, Miles; Rosen, Irene; Skoug, Ruth M.; Slagle, Amanda; Steinberg, John T.; Stevens, Michael L.; Szabo, Adam; Taylor, Ellen R.; Tiu, Chris; Turin, Paul; Velli, Marco; Webb, Gary; Whittlesey, Phyllis; Wright, Ken; Wu, S. T.; Zank, Gary 2016-12-01 The Solar Wind Electrons Alphas and Protons (SWEAP) Investigation on Solar Probe Plus is a four sensor instrument suite that provides complete measurements of the electrons and ionized helium and hydrogen that constitute the bulk of solar wind and coronal plasma. SWEAP consists of the Solar Probe Cup (SPC) and the Solar Probe Analyzers (SPAN). SPC is a Faraday Cup that looks directly at the Sun and measures ion and electron fluxes and flow angles as a function of energy. SPAN consists of an ion and electron electrostatic analyzer (ESA) on the ram side of SPP (SPAN-A) and an electron ESA on the anti-ram side (SPAN-B). The SPAN-A ion ESA has a time of flight section that enables it to sort particles by their mass/charge ratio, permitting differentiation of ion species. SPAN-A and -B are rotated relative to one another so their broad fields of view combine like the seams on a baseball to view the entire sky except for the region obscured by the heat shield and covered by SPC. Observations by SPC and SPAN produce the combined field of view and measurement capabilities required to fulfill the science objectives of SWEAP and Solar Probe Plus. SWEAP measurements, in concert with magnetic and electric fields, energetic particles, and white light contextual imaging will enable discovery and understanding of solar wind acceleration and formation, coronal and solar wind heating, and particle acceleration in the inner heliosphere of the solar system. SPC and SPAN are managed by the SWEAP Electronics Module (SWEM), which distributes power, formats onboard data products, and serves as a single electrical interface to the spacecraft. SWEAP data products include ion and electron velocity distribution functions with high energy and angular resolution. Full resolution data are stored within the SWEM, enabling high resolution observations of structures such as shocks, reconnection events, and other transient structures to be selected for download after the fact. This paper describes </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...812..170T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...812..170T">Thermalization of Heavy Ions in the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tracy, Patrick J.; Kasper, Justin C.; Zurbuchen, Thomas H.; Raines, Jim M.; Shearer, Paul; Gilbert, Jason 2015-10-01 Observations of velocity distribution functions from the Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer heavy ion composition instrument are used to calculate ratios of kinetic temperature and Coulomb collisional interactions of an unprecedented 50 ion species in the solar wind. These ions cover a mass per charge range of 1-5.5 amu/e and were collected in the time range of 1998-2011. We report the first calculation of the Coulomb thermalization rate between each of the heavy ion (A > 4 amu) species present in the solar wind along with protons (H+) and alpha particles (He2+). From these rates, we find that protons are the dominant source of Coulomb collisional thermalization for heavy ions in the solar wind and use this fact to calculate a collisional age for those heavy ion populations. The heavy ion thermal properties are well organized by this collisional age, but we find that the temperature of all heavy ions does not simply approach that of protons as Coulomb collisions become more important. We show that He2+ and C6+ follow a monotonic decay toward equal temperatures with protons with increasing collisional age, but O6+ shows a noted deviation from this monotonic decay. Furthermore, we show that the deviation from monotonic decay for O6+ occurs in solar wind of all origins, as determined by its Fe/O ratio. The observed differences in heavy ion temperature behavior point toward a local heating mechanism that favors ions depending on their charge and mass. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003hst..prop10083C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003hst..prop10083C">HST UV Images of Saturn's Aurora Coordinated with Cassini Solar Wind Measurements</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Clarke, John 2003-07-01 A key measurement goal of the Cassini mission to Saturn is to obtain simultaneous solar wind and auroral imaging measurements in a campaign scheduled for Jan. 2004. Cassini will measure the solar wind approaching Saturn continuously from 9 Jan. - 6 Feb., but not closer to Saturn due to competing spacecraft orientation constraints. The only system capable of imaging Saturn's aurora in early 2004 will be HST. In this community DD proposal we request the minimum HST time needed to support the Cassini mission during the solar wind campaign with UV images of Saturn's aurora. Saturn's magnetosphere is intermediate between the "closed" Jovian case with large internal sources of plasma and the Earth's magnetosphere which is open to solar wind interactions. Saturn's aurora has been shown to exhibit large temporal variations in brightness and morphology from Voyager and HST observations. Changes of auroral emitted power exceeding one order of magnitude, dawn brightenings, and latitudinal motions of the main oval have all been observed. Lacking knowledge of solar wind conditions near Saturn, it has not been possible to determine its role in Saturn's auroral processes, nor the mechanisms controlling the auroral precipitation. During Cassini's upcoming approach to Saturn there will be a unique opportunity to answer these questions. We propose to image one complete rotation of Saturn to determine the corotational and longitudinal dependences of the auroral activity. We will then image the active sector of Saturn once every two days for a total coverage of 26 days during the Cassini campaign to measure the upstream solar wind parameters. This is the minimum coverage needed to ensure observations of the aurora under solar wind pressure variations of more than a factor of two, based on the solar wind pressure variations measured by Voyager 2 near Saturn on the declining phase of solar activity. The team of proposers has carried out a similar coordinated observing campaign of </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH11B2453R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH11B2453R">Global solar magetic field organization in the extended corona: influence on the solar wind speed and density over the cycle.</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Réville, V.; Velli, M.; Brun, S. 2017-12-01 The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11yr solar cycle. For instance, the wind terminal velocity is thought to be anti-correlated with the expansion factor, a measure of how the magnetic field varies with height in the solar corona, usually computed at a fixed height (≈ 2.5 Rȯ, the source surface radius which approximates the distance at which all magnetic field lines become open). However, the magnetic field expansion affects the solar wind in a more detailed way, its influence on the solar wind properties remaining significant well beyond the source surface: we demonstrate this using 3D global MHD simulations of the solar corona, constrained by surface magnetograms over half a solar cycle (1989-2001). For models to comply with the constraints provided by observed characteristics of the solar wind, namely, that the radial magnetic field intensity becomes latitude independent at some distance from the Sun (Ulysses observations beyond 1 AU), and that the terminal wind speed is anti-correlated with the mass flux, they must accurately describe expansion beyond the solar wind critical point (even up to 10Rȯ and higher in our model). We also show that near activity minimum, expansion in the higher corona beyond 2.5 Rȯ is actually the dominant process affecting the wind speed. We discuss the consequences of this result on the necessary acceleration profile of the solar wind, the location of the sonic point and of the energy deposition by Alfvén waves. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH23D2692D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH23D2692D">Remote Sensing of the Solar Wind Density, Speed, and Temperature in the Region between the Sun and Parker Solar Probe</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Davila, J. M.; Reginald, N. L. 2017-12-01 A coronagraph is the tool of choice to understand and observe the structure of the corona from space. The novel coronagraph concept presented her provides a new scientific capability that will allow the measurement of density, temperature, and flow velocity in the solar atmosphere. This instrument will provide the first remote sensing measurement of the global solar wind temperature, density, and flow speed in the regions between 3 and 8 Rsun. It is in this region that the manority of the solar wind acceleration takes place, and where the ion compsition of the solar wind is "frozen in". This is also the region of the corona that links the surface of the Sun to the Parker Solar Probe and to Solar Orbiter. The observations suggested here would dramatically improve our understanding of solar wind formation and evolution in this critical region. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20100026391&hterms=figueroa&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfigueroa','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20100026391&hterms=figueroa&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfigueroa">Solar Wind Halo Formation by the Scattering of the Strahl via Direct Cluster/PEACE Observations of the 3D Velocity Distribution Function</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Figueroa-Vinas, Adolfo; Gurgiolo, Chris A.; Nieves-Chinchilla, Teresa; Goldstein, Melvyn L. 2010-01-01 It has been suggested by a number of authors that the solar wind electron halo can be formed by the scattering of the strahl. On frequent occasions we have observed in electron angular skymaps (Phi/Theta-plots) of the electron 3D velocity distribution functions) a bursty-filament of particles connecting the strahl to the solar wind core-halo. These are seen over a very limited energy range. When the magnetic field is well off the nominal solar wind flow direction such filaments are inconsistent with any local forces and are probably the result of strong scattering. Furthermore, observations indicates that the strahl component is frequently and significantly anisotropic (Tper/Tpal approx.2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism. The empirical observational evidence between the halo and the strahl suggests that the strahl population may be, at least in part, the source of the halo component. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SoPh..286..157S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SoPh..286..157S">Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Slemzin, V.; Harra, L.; Urnov, A.; Kuzin, S.; Goryaev, F.; Berghmans, D. 2013-08-01 The identification of solar-wind sources is an important question in solar physics. The existing solar-wind models ( e.g., the Wang-Sheeley-Arge model) provide the approximate locations of the solar wind sources based on magnetic field extrapolations. It has been suggested recently that plasma outflows observed at the edges of active regions may be a source of the slow solar wind. To explore this we analyze an isolated active region (AR) adjacent to small coronal hole (CH) in July/August 2009. On 1 August, Hinode/EUV Imaging Spectrometer observations showed two compact outflow regions in the corona. Coronal rays were observed above the active-region coronal hole (ARCH) region on the eastern limb on 31 July by STEREO-A/EUVI and at the western limb on 7 August by CORONAS- Photon/TESIS telescopes. In both cases the coronal rays were co-aligned with open magnetic-field lines given by the potential field source surface model, which expanded into the streamer. The solar-wind parameters measured by STEREO-B, ACE, Wind, and STEREO-A confirmed the identification of the ARCH as a source region of the slow solar wind. The results of the study support the suggestion that coronal rays can represent signatures of outflows from ARs propagating in the inner corona along open field lines into the heliosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840014950','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840014950">Wind and solar powered turbine</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Wells, I. D.; Koh, J. L.; Holmes, M. (Inventor) 1984-01-01 A power generating station having a generator driven by solar heat assisted ambient wind is described. A first plurality of radially extendng air passages direct ambient wind to a radial flow wind turbine disposed in a centrally located opening in a substantially disc-shaped structure. A solar radiation collecting surface having black bodies is disposed above the fist plurality of air passages and in communication with a second plurality of radial air passages. A cover plate enclosing the second plurality of radial air passages is transparent so as to permit solar radiation to effectively reach the black bodies. The second plurality of air passages direct ambient wind and thermal updrafts generated by the black bodies to an axial flow turbine. The rotating shaft of the turbines drive the generator. The solar and wind drien power generating system operates in electrical cogeneration mode with a fuel powered prime mover. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SSRv..172..209E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SSRv..172..209E">On the Role of Interchange Reconnection in the Generation of the Slow Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Edmondson, J. K. 2012-11-01 The heating of the solar corona and therefore the generation of the solar wind, remain an active area of solar and heliophysics research. Several decades of in situ solar wind plasma observations have revealed a rich bimodal solar wind structure, well correlated with coronal magnetic field activity. Therefore, the reconnection processes associated with the large-scale dynamics of the corona likely play a major role in the generation of the slow solar wind flow regime. In order to elucidate the relationship between reconnection-driven coronal magnetic field structure and dynamics and the generation of the slow solar wind, this paper reviews the observations and phenomenology of the solar wind and coronal magnetic field structure. The geometry and topology of nested flux systems, and the (interchange) reconnection process, in the context of coronal physics is then explained. Once these foundations are laid out, the paper summarizes several fully dynamic, 3D MHD calculations of the global coronal system. Finally, the results of these calculations justify a number of important implications and conclusions on the role of reconnection in the structural dynamics of the coronal magnetic field and the generation of the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170007773&hterms=solar+geometry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsolar%2Bgeometry','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170007773&hterms=solar+geometry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsolar%2Bgeometry">Formation of Heliospheric Arcs of Slow Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Higginson, A. K.; Antiochos, S. K.; Devore, C. R.; Wyper, P. F.; Zurbuchen, T. H. 2017-01-01 A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun's atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22654484-formation-heliospheric-arcs-slow-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22654484-formation-heliospheric-arcs-slow-solar-wind">Formation of Heliospheric Arcs of Slow Solar Wind</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Higginson, A. K.; Zurbuchen, T. H.; Antiochos, S. K. A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun’s atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchangemore » reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29398983','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29398983">Data Assimilation in the Solar Wind: Challenges and First Results.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Lang, Matthew; Browne, Philip; van Leeuwen, Peter Jan; Owens, Mathew 2017-11-01 Data assimilation (DA) is used extensively in numerical weather prediction (NWP) to improve forecast skill. Indeed, improvements in forecast skill in NWP models over the past 30 years have directly coincided with improvements in DA schemes. At present, due to data availability and technical challenges, DA is underused in space weather applications, particularly for solar wind prediction. This paper investigates the potential of advanced DA methods currently used in operational NWP centers to improve solar wind prediction. To develop the technical capability, as well as quantify the potential benefit, twin experiments are conducted to assess the performance of the Local Ensemble Transform Kalman Filter (LETKF) in the solar wind model ENLIL. Boundary conditions are provided by the Wang-Sheeley-Arge coronal model and synthetic observations of density, temperature, and momentum generated every 4.5 h at 0.6 AU. While in situ spacecraft observations are unlikely to be routinely available at 0.6 AU, these techniques can be applied to remote sensing of the solar wind, such as with Heliospheric Imagers or interplanetary scintillation. The LETKF can be seen to improve the state at the observation location and advect that improvement toward the Earth, leading to an improvement in forecast skill in near-Earth space for both the observed and unobserved variables. However, sharp gradients caused by the analysis of a single observation in space resulted in artificial wavelike structures being advected toward Earth. This paper is the first attempt to apply DA to solar wind prediction and provides the first in-depth analysis of the challenges and potential solutions. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990028046&hterms=Open+Field&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DOpen%2BField','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990028046&hterms=Open+Field&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DOpen%2BField">Signature of open magnetic field lines in the extended solar corona and of solar wind acceleration</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Antonucci, E.; Giordano, S.; Benna, C.; Kohl, J. L.; Noci, G.; Michels, J.; Fineschi, S. 1997-01-01 The observations carried out with the ultraviolet coronagraph spectrometer onboard the Solar and Heliospheric Observatory (SOHO) are discussed. The purpose of the observations was to determine the line of sight and radial velocity fields in coronal regions with different magnetic topology. The results showed that the regions where the high speed solar wind flows along open field lines are characterized by O VI 1032 and HI Lyman alpha 1216 lines. The global coronal maps of the line of sight velocity were reconstructed. The corona height, where the solar wind reaches 100 km/s, was determined. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22520043-energy-dissipation-processes-solar-wind-turbulence','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22520043-energy-dissipation-processes-solar-wind-turbulence">ENERGY DISSIPATION PROCESSES IN SOLAR WIND TURBULENCE</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Wang, Y.; Wei, F. S.; Feng, X. S. Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation ultimately cannot be achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the dissipation range, while the ambientmore » solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy dissipation process.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JASTP.147...21M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JASTP.147...21M">Solar activity variations of nocturnal thermospheric meridional winds over Indian longitude sector</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Madhav Haridas, M. K.; Manju, G.; Arunamani, T. 2016-09-01 The night time F-layer base height information from ionosondes located at two equatorial stations Trivandrum (TRV 8.5°N, 77°E) and Sriharikota (SHAR 13.7°N, 80.2°E) spanning over two decades are used to derive the climatology of equatorial nocturnal Thermospheric Meridional Winds (TMWs) prevailing during High Solar Activity (HSA) and Low Solar Activity (LSA) epochs. The important inferences from the analysis are 1) Increase in mean equatorward winds observed during LSA compared to HSA during pre midnight hours; 25 m/s for VE (Vernal Equinox) and 20 m/s for SS (Summer Solstice), AE (autumnal Equinox) and WS (Winter Solstice). 2) Mean wind response to Solar Flux Unit (SFU) is established quantitatively for all seasons for pre-midnight hours; rate of increase is 0.25 m/s/SFU for VE, 0.2 m/s/SFU for SS and WS and 0.08 m/s/SFU for AE. 3) Theoretical estimates of winds for the two epochs are performed and indicate the role of ion drag forcing as a major factor influencing TMWs. 4) Observed magnitude of winds and rate of flux dependencies are compared to thermospheric wind models. 5) Equinoctial asymmetry in TMWs is observed for HSA at certain times, with more equatorward winds during AE. These observations lend a potential to parameterize the wind components and effectively model the winds, catering to solar activity variations. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110016219&hterms=open+source&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dopen%2Bsource','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110016219&hterms=open+source&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dopen%2Bsource">A Model fot the Sources of the Slow Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Antiochos, S. K.; Mikic, Z.; Titov, V. S.; Lionello, R.; Linker, J. A. 2011-01-01 Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to approx.60deg, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind, and magnetic field for a time period preceding the 2008 August 1 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere and propose further tests of the model. Key words: solar wind - Sun: corona - Sun: magnetic topology </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070018822','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070018822">Composition of the Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Suess, S. T. 2007-01-01 The solar wind reflects the composition of the Sun and physical processes in the corona. Analysis produces information on how the solar system was formed and on physical processes in the corona. The analysis can also produce information on the local interstellar medium, galactic evolution, comets in the solar wind, dust in the heliosphere, and matter escaping from planets. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020006321&hterms=micro+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmicro%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020006321&hterms=micro+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmicro%2Bwind">Exploration of Solar Wind Acceleration Region Using Interplanetary Scintillation of Water Vapor Maser Source and Quasars</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Tokumaru, Munetoshi; Yamauchi, Yohei; Kondo, Tetsuro 2001-01-01 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 solar wind, which is the key region for the study of the solar wind 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. Solar wind speeds derived from Kashima IPS data suggest that the solar wind acceleration takes place at radial distances between 10 and 30 solar 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 solar wind acceleration region. While the solar wind in the maximum phase appears to be dominated by the slow wind, fast and rarefied winds associated with the coronal holes were found to develop significantly at high latitudes as the solar activity declined. Nevertheless, the Kashima data suggests that the location of the acceleration region is stable throughout the solar cycle. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020011026&hterms=quasar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dquasar','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020011026&hterms=quasar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dquasar">Exploration of Solar Wind Acceleration Region Using Interplanetary Scintillation of Water Vapor Maser Source and Quasars</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Tokumaru, Munetoshi; Yamauchi, Yohei; Kondo, Tetsuro 2001-01-01 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 solar wind, which is the key region for the study of the solar wind 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. Solar wind velocities derived from Kashima IPS data suggest that the solar wind acceleration takes place at radial distances between 10 and 30 solar 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 solar wind acceleration region. While the solar wind in the maximum phase appears to be dominated by the slow wind, fast and rarefied winds associated with coronal holes are found to develop significantly at high latitudes as the solar activity declines. Nevertheless, Kashima data suggests that the location of the acceleration region is stable throughout the solar cycle. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.6150H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.6150H">Solar wind controls on Mercury's magnetospheric cusp</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> He, Maosheng; Vogt, Joachim; Heyner, Daniel; Zhong, Jun 2017-06-01 This study assesses the response of the cusp to solar wind changes comprehensively, using 2848 orbits of MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) observation. The assessment entails four steps: (1) propose and validate an approach to estimate the solar wind magnetic field (interplanetary magnetic field (IMF)) for MESSENGER's cusp transit; (2) define an index σ measuring the intensity of the magnetic disturbance which significantly peaks within the cusp and serves as an indicator of the cusp activity level; (3) construct an empirical model of σ as a function of IMF and Mercury's heliocentric distance rsun, through linear regression; and (4) use the model to estimate and compare the polar distribution of the disturbance σ under different conditions for a systematic comparison. The comparison illustrates that the disturbance peak over the cusp is strongest and widest extending in local time for negative IMF Bx and negative IMF Bz, and when Mercury is around the perihelion. Azimuthal shifts are associated with both IMF By and rsun: the cusp moves toward dawn when IMF By or rsun decrease. These dependences are explained in terms of the IMF Bx-controlled dayside magnetospheric topology, the component reconnection model applied to IMF By and Bz, and the variability of solar wind ram pressure associated with heliocentric distance rsun. The applicability of the component reconnection model on IMF By indicates that at Mercury reconnection occurs at lower shear angles than at Earth.<abstract type="synopsis"><title type="main">Plain Language SummaryMercury's magnetosphere was suggested to be particularly sensitive to solar wind conditions. This study investigates the response of the magnetospheric cusp to solar wind conditions systematically. For this purpose, we analyze the statistical predictability of interplanetary magnetic field (IMF) at Mercury, develop an approach for estimating the solar wind magnetic field (IMF) for MErcury Surface </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active">11</li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active">12</li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003MmSAI..74..733A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003MmSAI..74..733A">Acceleration region of the slow solar wind in corona</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Abbo, L.; Antonucci, E.; Mikić, Z.; Riley, P.; Dodero, M. A.; Giordano, S. We present the results of a study concerning the physical parameters of the plasma of the extended corona in the low-latitude and equatorial regions, in order to investigate the sources of the slow solar wind during the minimum of solar activity. The equatorial streamer belt has been observed with the Ultraviolet Coronagraph Spectrometer (UVCS) onboard SOHO from August 19 to September 1, 1996. The spectroscopic diagnostic technique applied in this study, based on the OVI 1032, 1037 Ålines, allows us to determine both the solar wind velocity and the electron density of the extended corona. The main result of the analysis is the identification of the acceleration region of the slow wind, whose outflow velocity is measured in the range from 1.7 up to 3.5 solar radii. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM34A..01H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM34A..01H">Kinetic Interactions Between the Solar Wind and Lunar Magnetic Fields</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Halekas, J. S.; Poppe, A. R.; Fatemi, S.; Turner, D. L.; Holmstrom, M. 2016-12-01 Despite their relatively weak strength, small scale, and incoherence, lunar magnetic anomalies can affect the incoming solar wind flow. The plasma interaction with lunar magnetic fields drives significant compressions of the solar wind plasma and magnetic field, deflections of the incoming flow, and a host of plasma waves ranging from the ULF to the electrostatic range. Recent work suggests that the large-scale features of the solar wind-magnetic anomaly interactions may be driven by ion-ion instabilities excited by reflected ions, raising the possibility that they are analogous to ion foreshock phenomena. Indeed, despite their small scale, many of the phenomena observed near lunar magnetic anomalies appear to have analogues in the foreshock regions of terrestrial planets. We discuss the charged particle distributions, fields, and waves observed near lunar magnetic anomalies, and place them in a context with the foreshocks of the Earth, Mars, and other solar system objects. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.9552J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.9552J">MAVEN observations of the Mars upper atmosphere, ionosphere, and solar wind interactions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jakosky, Bruce M. 2017-09-01 The Mars Atmosphere and Volatile Evolution (MAVEN) mission to Mars has been operating in orbit for more than a full Martian year. Observations are dramatically changing our view of the Mars upper atmosphere system, which includes the upper atmosphere, ionosphere, coupling to the lower atmosphere, magnetosphere, and interactions with the Sun and the solar wind. The data are allowing us to understand the processes controlling the present-day structure of the upper atmosphere and the rates of escape of gas to space. These will tell us the role that escape to space has played in the evolution of the Mars atmosphere and climate. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH43A..03W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH43A..03W">Turbulent Heating and Wave Pressure in Solar Wind Acceleration Modeling: New Insights to Empirical Forecasting of the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Woolsey, L. N.; Cranmer, S. R. 2013-12-01 The study of solar wind acceleration has made several important advances recently due to improvements in modeling techniques. Existing code and simulations test the competing theories for coronal heating, which include reconnection/loop-opening (RLO) models and wave/turbulence-driven (WTD) models. In order to compare and contrast the validity of these theories, we need flexible tools that predict the emergent solar wind properties from a wide range of coronal magnetic field structures such as coronal holes, pseudostreamers, and helmet streamers. ZEPHYR (Cranmer et al. 2007) is a one-dimensional magnetohydrodynamics code that includes Alfven wave generation and reflection and the resulting turbulent heating to accelerate solar wind in open flux tubes. We present the ZEPHYR output for a wide range of magnetic field geometries to show the effect of the magnetic field profiles on wind properties. We also investigate the competing acceleration mechanisms found in ZEPHYR to determine the relative importance of increased gas pressure from turbulent heating and the separate pressure source from the Alfven waves. To do so, we developed a code that will become publicly available for solar wind prediction. This code, TEMPEST, provides an outflow solution based on only one input: the magnetic field strength as a function of height above the photosphere. It uses correlations found in ZEPHYR between the magnetic field strength at the source surface and the temperature profile of the outflow solution to compute the wind speed profile based on the increased gas pressure from turbulent heating. With this initial solution, TEMPEST then adds in the Alfven wave pressure term to the modified Parker equation and iterates to find a stable solution for the wind speed. This code, therefore, can make predictions of the wind speeds that will be observed at 1 AU based on extrapolations from magnetogram data, providing a useful tool for empirical forecasting of the sol! ar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840005052','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840005052">Quasi-steady solar wind dynamics</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Pizzo, V. J. 1983-01-01 Progress in understanding the large scale dynamics of quasisteady, corotating solar wind structure was reviewed. The nature of the solar wind at large heliocentric distances preliminary calculations from a 2-D MHD model are used to demonstrate theoretical expectations of corotating structure out to 30 AU. It is found that the forward and reverse shocks from adjacent CIR's begin to interact at about 10 AU, producing new shock pairs flanking secondary CIR's. These sawtooth secondary CIR's interact again at about 20 AU and survive as visible entities to 30 AU. The model predicts the velocity jumps at the leading edge of the secondary CIR's at 30 AU should be very small but there should still be sizable variations in the thermodynamic and magnetic parameters. The driving dynamic mechanism in the distant solar wind is the relaxation of pressure gradients. The second topic is the influence of weak, nonimpulsive time dependence in quasisteady dynamics. It is suggested that modest large scale variations in the coronal flow speed on periods of several hours to a day may be responsible for many of the remaining discrepancies between theory and observation. Effects offer a ready explanation for the apparent rounding of stream fronts between 0.3 and 1.0 AU discovered by Helios. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.963K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.963K">Solar Wind Plasma Flows and Space Weather Aspects Recent Solar Cycle</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kaushik, Sonia; Kaushik, Subhash Chandra 2016-07-01 Solar transients are responsible for initiating short - term and long - term variations in earth's magnetosphere. These variations are termed as geomagnetic disturbances, and driven by the interaction of solar wind features with the geo-magnetosphere. The strength of this modulation process depends upon the magnitude and orientation of the Interplanetary Magnetic Field and solar wind parameters. These interplanetary transients are large scale structures containing plasma and magnetic field expelled from the transient active regions of solar atmosphere. As they come to interplanetary medium the interplanetary magnetic field drape around them. This field line draping was thought as possible cause of the characteristic eastward deflection and giving rise to geomagnetic activities as well as a prime factor in producing the modulation effects in the near Earth environment. The Solar cycle 23 has exhibited the unique extended minima and peculiar effects in the geomagnetosphere. Selecting such transients, occurred during this interval, an attempt has been made to determine quantitative relationships of these transients with solar/ interplanetary and Geophysical Parameters. In this work we used hourly values of IMF data obtained from the NSSD Center. The analysis mainly based on looking into the effects of these transients on earth's magnetic field. The high-resolution data IMF Bz and solar wind data obtained from WDC-A, through its omniweb, available during the selected period. Dst and Ap obtained from WDC-Kyoto are taken as indicator of geomagnetic activities. It is found that Dst index, solar wind velocity, proton temperature and the Bz component of magnetic field have higher values and increase just before the occurrence of these events. Larger and varying magnetic field mainly responsible for producing the short-term changes in geomagnetic intensity are observed during these events associated with coronal holes. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018LRSP...15....1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018LRSP...15....1R">Solar wind stream interaction regions throughout the heliosphere</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Richardson, Ian G. 2018-01-01 This paper focuses on the interactions between the fast solar wind from coronal holes and the intervening slower solar wind, leading to the creation of stream interaction regions that corotate with the Sun and may persist for many solar rotations. Stream interaction regions have been observed near 1 AU, in the inner heliosphere (at ˜ 0.3-1 AU) by the Helios spacecraft, in the outer and distant heliosphere by the Pioneer 10 and 11 and Voyager 1 and 2 spacecraft, and out of the ecliptic by Ulysses, and these observations are reviewed. Stream interaction regions accelerate energetic particles, modulate the intensity of Galactic cosmic rays and generate enhanced geomagnetic activity. The remote detection of interaction regions using interplanetary scintillation and white-light imaging, and MHD modeling of interaction regions will also be discussed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhDT........23Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhDT........23Z">Simulation and optimum design of hybrid solar-wind and solar-wind-diesel power generation systems</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhou, Wei Solar and wind energy systems are considered as promising power generating sources due to its availability and topological advantages in local power generations. However, a drawback, common to solar and wind options, is their unpredictable nature and dependence on weather changes, both of these energy systems would have to be oversized to make them completely reliable. Fortunately, the problems caused by variable nature of these resources can be partially overcome by integrating these two resources in a proper combination to form a hybrid system. However, with the increased complexity in comparison with single energy systems, optimum design of hybrid system becomes more complicated. In order to efficiently and economically utilize the renewable energy resources, one optimal sizing method is necessary. This thesis developed an optimal sizing method to find the global optimum configuration of stand-alone hybrid (both solar-wind and solar-wind-diesel) power generation systems. By using Genetic Algorithm (GA), the optimal sizing method was developed to calculate the system optimum configuration which offers to guarantee the lowest investment with full use of the PV array, wind turbine and battery bank. For the hybrid solar-wind system, the optimal sizing method is developed based on the Loss of Power Supply Probability (LPSP) and the Annualized Cost of System (ACS) concepts. The optimization procedure aims to find the configuration that yields the best compromise between the two considered objectives: LPSP and ACS. The decision variables, which need to be optimized in the optimization process, are the PV module capacity, wind turbine capacity, battery capacity, PV module slope angle and wind turbine installation height. For the hybrid solar-wind-diesel system, minimization of the system cost is achieved not only by selecting an appropriate system configuration, but also by finding a suitable control strategy (starting and stopping point) of the diesel generator. The </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH32A..03A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH32A..03A">A Deeper Understanding of Stability in the Solar Wind: Applying Nyquist's Instability Criterion to Wind Faraday Cup Data</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Alterman, B. L.; Klein, K. G.; Verscharen, D.; Stevens, M. L.; Kasper, J. C. 2017-12-01 Long duration, in situ data sets enable large-scale statistical analysis of free-energy-driven instabilities in the solar wind. The plasma beta and temperature anisotropy plane provides a well-defined parameter space in which a single-fluid plasma's stability can be represented. Because this reduced parameter space can only represent instability thresholds due to the free energy of one ion species - typically the bulk protons - the true impact of instabilities on the solar wind is under estimated. Nyquist's instability criterion allows us to systematically account for other sources of free energy including beams, drifts, and additional temperature anisotropies. Utilizing over 20 years of Wind Faraday cup and magnetic field observations, we have resolved the bulk parameters for three ion populations: the bulk protons, beam protons, and alpha particles. Applying Nyquist's criterion, we calculate the number of linearly growing modes supported by each spectrum and provide a more nuanced consideration of solar wind stability. Using collisional age measurements, we predict the stability of the solar wind close to the sun. Accounting for the free-energy from the three most common ion populations in the solar wind, our approach provides a more complete characterization of solar wind stability. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ems..confE.749Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ems..confE.749Q">Analysis of the solar/wind resources in Southern Spain for optimal sizing of hybrid solar-wind power generation systems</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Quesada-Ruiz, S.; Pozo-Vazquez, D.; Santos-Alamillos, F. J.; Lara-Fanego, V.; Ruiz-Arias, J. A.; Tovar-Pescador, J. 2010-09-01 A drawback common to the solar and wind energy systems is their unpredictable nature and dependence on weather and climate on a wide range of time scales. In addition, the variation of the energy output may not match with the time distribution of the load demand. This can partially be solved by the use of batteries for energy storage in stand-alone systems. The problem caused by the variable nature of the solar and wind resources can be partially overcome by the use of energy systems that uses both renewable resources in a combined manner, that is, hybrid wind-solar systems. Since both resources can show complementary characteristics in certain location, the independent use of solar or wind systems results in considerable over sizing of the batteries system compared to the use of hybrid solar-wind systems. Nevertheless, to the day, there is no single recognized method for properly sizing these hybrid wind-solar systems. In this work, we present a method for sizing wind-solar hybrid systems in southern Spain. The method is based on the analysis of the wind and solar resources on daily scale, particularly, its temporal complementary characteristics. The method aims to minimize the size of the energy storage systems, trying to provide the most reliable supply. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021350&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dorbiting%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021350&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dorbiting%2Bwind">Features of solar wind acceleration according to radio occultation data</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Efimov, A. I. 1995-01-01 In addressing one of the fundamental problems in solar physics establishing the mechanism(s) responsible for the solar wind acceleration and the corona heating - it is essential to have a reliable knowledge of the heliocentric radial dependence of the solar wind properties. Adequate data are available for small solar distances R less than 4 R(solar mass) from coronal white light and EUV observations and at distances R greater than 60 R(solar mass) from in situ measurements. One of the few methods available to fill in the gap between these boundaries is the radio scintillation technique. Taking the example of the solar wind velocity, the most reliable such measurements are obtained when phase fluctuation observations of scattered radio waves, which are not susceptible to saturation effects, are recorded at two or more widely-spaced ground stations. Two extensive observation campaigns of this type were carried out with the Venus-orbiting satellites Venera 10 in 1976 and Venera 15/16 in 1984. The observations were performed over the course of three months near superior conjunction at solar offset distances R approximately 6-80 R(solar mass). The main results from the subsequent analysis of these data are: (1) velocities vary between 250 and 380 km s(exp -1) for R greater than 20 R(solar mass), agreeing with similar measurements using natural sources (IPS); (2) velocities derived from two-station phase fluctuation observations varv between 70 and 120 km s(exp -1) for R less than 12 R(solar mass), i.e. values substantially lower than those derived from conventional IPS data; and (3) it is suggested that the different velocity profiles derived from the two data sets at small R may be due to the effects of magnetosonic and Alfvenic waves on radio wave scattering. Further analysis of additional radio sounding data should help resolve the apparent discrepancy. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRA..113.7101V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRA..113.7101V">Inherent length-scales of periodic solar wind number density structures</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Viall, N. M.; Kepko, L.; Spence, H. E. 2008-07-01 We present an analysis of the radial length-scales of periodic solar wind number density structures. We converted 11 years (1995-2005) of solar wind number density data into radial length series segments and Fourier analyzed them to identify all spectral peaks with radial wavelengths between 72 (116) and 900 (900) Mm for slow (fast) wind intervals. Our window length for the spectral analysis was 9072 Mm, approximately equivalent to 7 (4) h of data for the slow (fast) solar wind. We required that spectral peaks pass both an amplitude test and a harmonic F-test at the 95% confidence level simultaneously. From the occurrence distributions of these spectral peaks for slow and fast wind, we find that periodic number density structures occur more often at certain radial length-scales than at others, and are consistently observed within each speed range over most of the 11-year interval. For the slow wind, those length-scales are L ˜ 73, 120, 136, and 180 Mm. For the fast wind, those length-scales are L ˜ 187, 270 and 400 Mm. The results argue for the existence of inherent radial length-scales in the solar wind number density. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22654173-contribution-coronal-jets-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22654173-contribution-coronal-jets-solar-wind">THE CONTRIBUTION OF CORONAL JETS TO THE SOLAR WIND</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Lionello, R.; Török, T.; Titov, V. S. Transient collimated plasma eruptions in the solar corona, commonly known as coronal (or X-ray) jets, are among the most interesting manifestations of solar activity. It has been suggested that these events contribute to the mass and energy content of the corona and solar wind, but the extent of these contributions remains uncertain. We have recently modeled the formation and evolution of coronal jets using a three-dimensional (3D) magnetohydrodynamic (MHD) code with thermodynamics in a large spherical domain that includes the solar wind. Our model is coupled to 3D MHD flux-emergence simulations, i.e., we use boundary conditions provided by such simulationsmore » to drive a time-dependent coronal evolution. The model includes parametric coronal heating, radiative losses, and thermal conduction, which enables us to simulate the dynamics and plasma properties of coronal jets in a more realistic manner than done so far. Here, we employ these simulations to calculate the amount of mass and energy transported by coronal jets into the outer corona and inner heliosphere. Based on observed jet-occurrence rates, we then estimate the total contribution of coronal jets to the mass and energy content of the solar wind to (0.4–3.0)% and (0.3–1.0)%, respectively. Our results are largely consistent with the few previous rough estimates obtained from observations, supporting the conjecture that coronal jets provide only a small amount of mass and energy to the solar wind. We emphasize, however, that more advanced observations and simulations (including parametric studies) are needed to substantiate this conjecture.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E3124S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E3124S">Transient flows of the solar wind associated with small-scale solar activity in solar minimum</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Slemzin, Vladimir; Veselovsky, Igor; Kuzin, Sergey; Gburek, Szymon; Ulyanov, Artyom; Kirichenko, Alexey; Shugay, Yulia; Goryaev, Farid The data obtained by the modern high sensitive EUV-XUV telescopes and photometers such as CORONAS-Photon/TESIS and SPHINX, STEREO/EUVI, PROBA2/SWAP, SDO/AIA provide good possibilities for studying small-scale solar activity (SSA), which is supposed to play an important role in heating of the corona and producing transient flows of the solar wind. During the recent unusually weak solar minimum, a large number of SSA events, such as week solar flares, small CMEs and CME-like flows were observed and recorded in the databases of flares (STEREO, SWAP, SPHINX) and CMEs (LASCO, CACTUS). On the other hand, the solar wind data obtained in this period by ACE, Wind, STEREO contain signatures of transient ICME-like structures which have shorter duration (<10h), weaker magnetic field strength (<10 nT) and lower proton temperature than usual ICMEs. To verify the assumption that ICME-like transients may be associated with the SSA events we investigated the number of weak flares of C-class and lower detected by SPHINX in 2009 and STEREO/EUVI in 2010. The flares were classified on temperature and emission measure using the diagnostic means of SPHINX and Hinode/EIS and were confronted with the parameters of the solar wind (velocity, density, ion composition and temperature, magnetic field, pitch angle distribution of the suprathermal electrons). The outflows of plasma associated with the flares were identified by their coronal signatures - CMEs (only in few cases) and dimmings. It was found that the mean parameters of the solar wind projected to the source surface for the times of the studied flares were typical for the ICME-like transients. The results support the suggestion that weak flares can be indicators of sources of transient plasma flows contributing to the slow solar wind at solar minimum, although these flows may be too weak to be considered as separate CMEs and ICMEs. The research leading to these results has received funding from the European Union’s Seventh Programme </li> <li> <a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70021905','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70021905">Estimated solar wind-implanted helium-3 distribution on the Moon</a> <a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a> Johnson, J. R.; Swindle, T.D.; Lucey, P.G. 1999-01-01 Among the solar wind-implanted volatiles present in the lunar regolith, 3 He is possibly the most valuable resource because of its potential as a fusion fuel. The abundance of 3 He in the lunar regolith at a given location depends on surface maturity, the amount of solar wind fluence, and titanium content, because ilmenite (FeTiO3) retains helium much better than other major lunar minerals. Surface maturity and TiO2 maps from Clementine multispectral data sets are combined here with a solar wind fluence model to produce a 3He abundance map of the Moon. Comparison of the predicted 3He values to landing site observations shows good correlation. The highest 3He abundances occur in the farside maria (due to greater solar wind fluence received) and in higher TiO2 nearside mare regions. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950038009&hterms=foreshock&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dforeshock','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950038009&hterms=foreshock&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dforeshock">Elsaesser variable analysis of fluctuations in the ion foreshock and undisturbed solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Labelle, James; Treumann, Rudolf A.; Marsch, Eckart 1994-01-01 Magnetohydrodynamics (MHD) fluctuations in the solar wind have been investigated previously by use of Elsaesser variables. In this paper, we present a comparison of the spectra of Elsaesser variables in the undisturbed solar wind at 1 AU and in the ion foreshock in front of the Earth. Both observations take place under relatively strong solar wind flow speed conditions (approximately equal 600 km/s). In the undisturbed solar wind we find that outward propagating Alfven waves dominate, as reported by other observers. In the ion foreshock the situation is more complex, with neither outward nor inward propagation dominating over the entire range investigated (1-10 mHz). Measurements of the Poynting vectors associated with the fluctuations are consistent with the Elsaesser variable analysis. These results generally support interpretations of the Elsaesser variables which have been made based strictly on solar wind data and provide additional insight into the nature of the ion foreshock turbulence. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120013113','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120013113">The S-Web Model for the Sources of the Slow Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Antiochos, Spiro K.; Karpen, Judith T.; DeVore, C. Richard 2012-01-01 Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind has large angular width, up to 60 degrees, suggesting that its source extends far from the open-closed boundary. We describe a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices (the S-Web) and quasi-separatrix layers in the heliosphere. We discuss the dynamics of the S-Web model and its implications for present observations and for the upcoming observations from Solar Orbiter and Solar Probe Plus. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730002080','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730002080">Elemental and isotopic abundances in the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Geiss, J. 1972-01-01 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH12A..03L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH12A..03L">The Solar Wind Source Cycle: Relationship to Dynamo Behavior</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Luhmann, J. G.; Li, Y.; Lee, C. O.; Jian, L. K.; Petrie, G. J. D.; Arge, C. N. 2017-12-01 Solar cycle trends of interest include the evolving properties of the solar wind, the heliospheric medium through which the Sun's plasmas and fields interact with Earth and the planets -including the evolution of CME/ICMEs enroute. Solar wind sources include the coronal holes-the open field regions that constantly evolve with solar magnetic fields as the cycle progresses, and the streamers between them. The recent cycle has been notably important in demonstrating that not all solar cycles are alike when it comes to contributions from these sources, including in the case of ecliptic solar wind. In particular, it has modified our appreciation of the low latitude coronal hole and streamer sources because of their relative prevalence. One way to understand the basic relationship between these source differences and what is happening inside the Sun and on its surface is to use observation-based models like the PFSS model to evaluate the evolution of the coronal field geometry. Although the accuracy of these models is compromised around solar maximum by lack of global surface field information and the sometimes non-potential evolution of the field related to more frequent and widespread emergence of active regions, they still approximate the character of the coronal field state. We use these models to compare the inferred recent cycle coronal holes and streamer belt sources of solar wind with past cycle counterparts. The results illustrate how (still) hemispherically asymmetric weak polar fields maintain a complex mix of low-to-mid latitude solar wind sources throughout the latest cycle, with a related marked asymmetry in the hemispheric distribution of the ecliptic wind sources. This is likely to be repeated until the polar field strength significantly increases relative to the fields at low latitudes, and the latter symmetrize. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18046399','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18046399">Little or no solar wind enters Venus' atmosphere at solar minimum.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Zhang, T L; Delva, M; Baumjohann, W; Auster, H-U; Carr, C; Russell, C T; Barabash, S; Balikhin, M; Kudela, K; Berghofer, G; Biernat, H K; Lammer, H; Lichtenegger, H; Magnes, W; Nakamura, R; Schwingenschuh, K; Volwerk, M; Vörös, Z; Zambelli, W; Fornacon, K-H; Glassmeier, K-H; Richter, I; Balogh, A; Schwarzl, H; Pope, S A; Shi, J K; Wang, C; Motschmann, U; Lebreton, J-P 2007-11-29 Venus has no significant internal magnetic field, which allows the solar wind to interact directly with its atmosphere. A field is induced in this interaction, which partially shields the atmosphere, but we have no knowledge of how effective that shield is at solar minimum. (Our current knowledge of the solar wind interaction with Venus is derived from measurements at solar maximum.) The bow shock is close to the planet, meaning that it is possible that some solar wind could be absorbed by the atmosphere and contribute to the evolution of the atmosphere. Here we report magnetic field measurements from the Venus Express spacecraft in the plasma environment surrounding Venus. The bow shock under low solar activity conditions seems to be in the position that would be expected from a complete deflection by a magnetized ionosphere. Therefore little solar wind enters the Venus ionosphere even at solar minimum. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active">12</li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active">13</li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017hst..prop15299A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017hst..prop15299A">Weaving the history of the solar wind with magnetic field lines</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Alvarado Gomez, Julian 2017-08-01 Despite its fundamental role for the evolution of the solar system, our observational knowledge of the wind properties of the young Sun comes from a single stellar observation. This unexpected fact for a field such as astrophysics arises from the difficulty of detecting Sun-like stellar winds. Their detection relies on the appearance of an astrospheric signature (from the stellar wind-ISM interaction region), visible only with the aid of high-resolution HST Lyman-alpha spectra. However, observations and modelling of the present day Sun have revealed that magnetic fields constitute the main driver of the solar wind, providing guidance on how such winds would look like back in time. In this context we propose observations of four young Sun-like stars in order to detect their astrospheres and characterise their stellar winds. For all these objects we have recovered surface magnetic field maps using the technique of Zeeman Doppler Imaging, and developed detailed wind models based on these observed field distributions. Even a single detection would represent a major step forward for our understanding of the history of the solar wind, and the outflows in more active stars. Mass loss rate estimates from HST will be confronted with predictions from realistic models of the corona/stellar wind. In one of our objects the comparison would allow us to quantify the wind variability induced by the magnetic cycle of a star, other than the Sun, for the first time. Three of our targets are planet hosts, thus the HST spectra would also provide key information on the high-energy environment of these systems, guaranteeing their legacy value for the growing field of exoplanet characterisation. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170002772&hterms=electrons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Delectrons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170002772&hterms=electrons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Delectrons">On Electron-Scale Whistler Turbulence in the Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K.-H.; Motschmann, U.; Giles, B.; Magnes, W.; Fischer, D.; Torbert, R. B.; Russell, C. T. 2016-01-01 For the first time, the dispersion relation for turbulence magnetic field fluctuations in the solar wind is determined directly on small scales of the order of the electron inertial length, using four-point magnetometer observations from the Magnetospheric Multiscale mission. The data are analyzed using the high-resolution adaptive wave telescope technique. Small-scale solar wind turbulence is primarily composed of highly obliquely propagating waves, with dispersion consistent with that of the whistler mode. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhDT.........6F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhDT.........6F">A Study of Fermi Acceleration of Suprathermal Solar Wind Ions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Freeman, Theodore James The Wind spacecraft has observed numerous sunward bursts of ~2 MeV ions upstream of the Earth's bow shock. The bursts typically last several minutes at the highest energies, but they can last for tens of minutes at intermediate energies (tens to hundreds of keV). The MeV ions are not protons or alpha particles, and are probably oxygen ions. There are two possible sources of these particles: Fermi acceleration of solar wind ions, and ring current particles which have escaped from the Earth's magnetosphere. In this dissertation, Wind observations and numerical particle simulations of Fermi acceleration are presented which demonstrate that suprathermal solar wind O6+ ions are the most likely source of these bursts. Since the Fermi mechanism accelerates all ions to approximately the same ratio of energy to charge, H+ and He2+ ions are accelerated to much lower energies than O6+ ions. In this model, suprathermal ions are reflected between the bow shock and rotations in the interplanetary magnetic field (IMF) upstream of the shock, gaining energy due to the relative motion of the reflecting magnetic structures. Each burst either coincides with or is closely followed by a large IMF rotation. By using measured magnetic field data, the timing of the bursts detected by Wind is precisely reproduced in the simulation. The energy spectra observed by Wind are also reproduced by adding H+ , He2+ , and O6+ fluxes together, and assuming that there is an increase of ~2 orders of magnitude in the high energy tail of the solar wind oxygen distribution. An enhancement of this order of magnitude in CNO group ions was measured by the ion composition experiment on Wind in association with these bursts. An examination of the magnetospheric escape model shows that while escaping O+ ions can account for some features of the data, such as the longer bursts of intermediate energy ions, it cannot account for the short duration ~2 MeV bursts themselves, because O+ ions scatter diffusively in the </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22126793-solar-wind-heavy-ions-over-solar-cycle-ace-swics-measurements','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22126793-solar-wind-heavy-ions-over-solar-cycle-ace-swics-measurements">SOLAR WIND HEAVY IONS OVER SOLAR CYCLE 23: ACE/SWICS MEASUREMENTS</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Lepri, S. T.; Landi, E.; Zurbuchen, T. H. 2013-05-01 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 movedmore » 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.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020022191&hterms=fall&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D80%26Ntt%3Dfall','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020022191&hterms=fall&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D80%26Ntt%3Dfall">Low-Latitude Solar Wind During the Fall 1998 SOHO-Ulysses Quadrature</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Poletto, G.; Suess, Steven T.; Biesecker, D.; Esser, R.; Gloeckler, G.; Zurbuchen, T.; Whitaker, Ann F. (Technical Monitor) 2001-01-01 The Fall 1998 SOlar-Heliospheric Observatory (SOHO) - Ulysses quadrature occurred when Ulysses was at 5.2 AU, 17.4 deg South of the equator, and off the West line of the Sun. SOHO coronal observations, at heliocentric distances of a few solar radii, showed that the line through the solar center and Ulysses crossed, over the first days of observations, a dark, weakly emitting area and through the northern edge of a streamer complex during the second half of the quadrature campaign. Ulysses in situ observations showed this transition to correspond to a decrease from higher speed wind typical of coronal hole flow to low speed wind. Physical parameters (density, temperature, flow speed) of the low latitude coronal plasma sampled over the campaign are determined using constraints from what is the same plasma measured later in situ and simulating the intensities of the Hydrogen Lyman-alpha and OVI 1032 and 1037 Angstrom lines, measured by the Ultra Violet Coronagraph Spectrometer (UVCS) on SOHO. The densities, temperatures and outflow speed are compared with the same characteristic flow parameters for high-latitude fast wind streams and typical slow solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH32A..08M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH32A..08M">Nonlinear Evolution of Observed Fast Streams in the Solar Wind - Micro-instabilities and Energy Exchange between Protons and Alpha Particles</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Maneva, Y. G.; Poedts, S. 2017-12-01 Non-thermal kinetic components such as deformed velocity distributions, temperature anisotropies and relative drifts between the multiple ion populations are frequently observed features in the collisionless fast solar wind streams near the Earth whose origin is still to be better understood. Some of the traditional models consider the formation of the temperature anisotropies through the effect of the solar wind expansion, while others assume in situ heating and particle acceleration by local fluctuations, such as plasma waves, or by spacial structures, such as advected or locally generated current sheets. In this study we consider the evolution of initial ion temperature anisotropies and relative drifts in the presence of plasma oscillations, such as ion-cyclotron and kinetic Alfven waves. We perform 2.5D hybrid simulations to study the evolution of observed fast solar wind plasma parcels, including the development of the plasma micro-instabilities, the field-particle correlations and the energy transfer between the multiple ion species. We consider two distinct cases of highly anisotropic and quickly drifting protons which excite ion-cyclotron waves and of moderately anisotropic slower protons, which co-exist with kinetic Alfven waves. The alpha particles for both cases are slightly anisotropic in the beginning and remain anisotropic throughout the simulation time. Both the imposed magnetic fluctuations and the initial differential streaming decrease in time for both cases, while the minor ions are getting heated. Finally we study the effects of the solar wind expansion and discuss its implications for the nonlinear evolution of the system. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPP.M9004E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPP.M9004E">Magnetic pumping of the solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Egedal, Jan; Lichko, Emily; Daughton, William 2015-11-01 The transport of matter and radiation in the solar wind and terrestrial magnetosphere is a complicated problem involving competing processes of charged particles interacting with electric and magnetic fields. Given the rapid expansion of the solar wind, it would be expected that superthermal electrons originating in the corona would cool rapidly as a function of distance to the Sun. However, this is not observed, and various models have been proposed as candidates for heating the solar wind. In the compressional pumping mechanism explored by Fisk and Gloeckler particles are accelerated by random compressions by the interplanetary wave turbulence. This theory explores diffusion due to spatial non-uniformities and provides a mechanism for redistributing particle. For investigation of a related but different heating mechanism, magnetic pumping, in our work we include diffusion of anisotropic features that develops in velocity space. The mechanism allows energy to be transferred to the particles directly from the turbulence. Guided by kinetic simulations a theory is derived for magnetic pumping. At the heart of this work is a generalization of the Parker Equation to capture the role of the pressure anisotropy during the pumping process. Supported by NASA grant NNX15AJ73G. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MPLB...3240009S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MPLB...3240009S">Numerical simulation of wind loads on solar panels</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Su, Kao-Chun; Chung, Kung-Ming; Hsu, Shu-Tsung 2018-05-01 Solar panels mounted on the roof of a building or ground are often vulnerable to strong wind loads. This study aims to investigate wind loads on solar panels using computational fluid dynamic (CFD). The results show good agreement with wind tunnel data, e.g. the streamwise distribution of mean surface pressure coefficient of a solar panel. Wind uplift for solar panels with four aspect ratios is evaluated. The effect of inclined angle and clearance (or height) of a solar panel is addressed. It is found that wind uplift of a solar panel increases when there is an increase in inclined angle and the clearance above ground shows an opposite effect. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AAS...21640521A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AAS...21640521A">A Model for the Sources of the Slow Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Antiochos, Spiro K.; Mikic, Z.; Lionello, R.; Titov, V.; Linker, J. 2010-05-01 Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed-field corona, implying that it originates at the open-closed field boundary layer, but it also has large angular width, up to 40 degrees. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We calculate with high numerical resolution, the quasi-steady solar wind and magnetic field for a Carrington rotation centered about the August 1, 2008 total solar eclipse. Our numerical results demonstrate that, at least for this time period, a web of separatrices (S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere, and propose further tests of the model. This work was supported, in part, by the NASA HTP, TR&T and SR&T programs. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810030288&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D90%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810030288&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D90%26Ntt%3Dlazarus">Deceleration of the solar wind in the earth's foreshock region - Isee 2 and Imp 8 observations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bonifazi, C.; Moreno, G.; Lazarus, A. J.; Sullivan, J. D. 1980-01-01 The deceleration of the solar wind in the region of the interplanetary space filled by ions backstreaming from the earth's bow shock and associated waves is studied using a two-spacecraft technique. This deceleration depends on the solar wind bulk velocity; at low velocities (below 300 km/s) the velocity decrease is about 5 km/s, while at higher velocities (above 400 km/s) the decrease may be as large as 30 km/s. The energy balance shows that the kinetic energy loss far exceeds the thermal energy which is possibly gained by the solar wind; therefore at least part of this energy must go into waves and/or into the backstreaming ions. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.nrel.gov/grid/solar-wind-forecasting.html','SCIGOVWS'); return false;" href="https://www.nrel.gov/grid/solar-wind-forecasting.html">Solar and Wind Forecasting | Grid Modernization | NREL</a> <a target="_blank" href="http://www.science.gov/aboutsearch.html">Science.gov Websites</a> and Wind Forecasting Solar and Wind Forecasting As solar and wind power become more common system operators. An aerial photo of the National Wind Technology Center's PV arrays. Capabilities value of accurate forecasting Wind power visualization to direct questions and feedback during industry </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AAS...22933909B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AAS...22933909B">Periodic Alpha Signatures and the Origins of the Slow Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Blume, Catherine; Kepko, Larry 2017-01-01 The origin of the slow solar wind has puzzled scientists for decades. Both flux tube geometry of field lines open to the heliosphere and magnetic reconnection that opens field lines that were previously closed to the heliosphere have been proposed as explanations (via the expansion factor and S-web models, respectively), but the observations to date have proven an inadequate test for distinguishing between the theories. However, short term (~hours) variability of alpha particles could provide the set of observations that tips the balance. Alpha particles compose about 4% of the solar wind, and its precise composition is determined by dynamics in the solar atmosphere. Therefore, compositional changes in the alpha to proton ratio must have originated at the Sun, making alphs tracer particles of sorts and carrying signatures of their solar creation. We examined in situ alpha density and proton density data from the Wind, ACE, STEREO-B, AND STEREO-A spacecraft, focusing on a pseudostreamer that occurred August 9, 2008. This case study found one clear periodic structure in the slow solar wind preceding the pseudostreamer in Wind/ACE and the same periodic structure in the in situ data at STEREO-B. The existence of this slow wind structure in association with a pseudostreamer directly contradicts the expansion factor model, which predicts that pseudostreamers produce fast wind. The structure's appearance at STEREO-B, which was located 30 degrees behind the Earth-Sun line, further indicates that the mechanism at the Sun is responsible for its formation was active for at least three days. Moreover, an analysis of both helmet streamer and pseudostreamer events between 2007-2009 finds that similar density structures exist in at least 35% of all streamers. This indicates that the same physical process that produces this slow solar wind occurs with a degree of frequency in association with both types of streamers. The clarity, duration, and frequency of these periodic density </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Icar..287..131H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Icar..287..131H">Pluto-Charon solar wind interaction dynamics</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hale, J. P. M.; Paty, C. S. 2017-05-01 This work studies Charon's effects on the Pluto-solar wind interaction using a multifluid MHD model which simulates the interactions of Pluto and Charon with the solar wind as well as with each other. Specifically, it investigates the ionospheric dynamics of a two body system in which either one or both bodies possess an ionosphere. Configurations in which Charon is directly upstream and directly downstream of Pluto are considered. Depending on ionospheric and solar wind conditions, Charon could periodically pass into the solar wind flow upstream of Pluto. The results of this study demonstrate that in these circumstances Charon modifies the upstream flow, both in the case in which Charon possesses an ionosphere, and in the case in which Charon is without an ionosphere. This modification amounts to a change in the gross structure of the interaction region when Charon possesses an ionosphere but is more localized when Charon lacks an ionosphere. Furthermore, evidence is shown that supports Charon acting to partially shield Pluto from the solar wind when it is upstream of Pluto, resulting in a decrease in ionospheric loss by Pluto. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790012789','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790012789">Contributions to the Fourth Solar Wind Conference. [interplanetary magnetic fields and medium</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Acuna, M. H.; Behannon, K. W.; Burlaga, L. F.; Lepping, R.; Ness, N.; Ogilvie, K.; Pizzo, J. 1979-01-01 Recent results in interplanetary physics are examined. These include observations of shock waves and post-shock magnetic fields made by Voyager 1, 2; observations of the electron temperature as a function of distance between 1.36 AU and 2.25 AU; and observations of the structure of sector boundaries observed by Helios 1. A theory of electron energy transport in the collisionless solar wind is presented, and compared with observations. Alfven waves and Alvenic fluctuations in the solar wind are also discussed. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810042382&hterms=history+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dhistory%2Btheory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810042382&hterms=history+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dhistory%2Btheory">Solar wind flow past Venus - Theory and comparisons</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spreiter, J. R.; Stahara, S. S. 1980-01-01 Advanced computational procedures are applied to an improved model of solar wind flow past Venus to calculate the locations of the ionopause and bow wave and the properties of the flowing ionosheath plasma in the intervening region. The theoretical method is based on a single-fluid, steady, dissipationless, magneto-hydrodynamic continuum model and is appropriate for the calculation of axisymmetric supersonic, super-Alfvenic solar wind flow past a nonmagnetic planet possessing a sufficiently dense ionosphere to stand off the flowing plasma above the subsolar point and elsewhere. Determination of time histories of plasma and magnetic field properties along an arbitrary spacecraft trajectory and provision for an arbitrary oncoming direction of the interplanetary solar wind have been incorporated in the model. An outline is provided of the underlying theory and computational procedures, and sample comparisons of the results are presented with observations from the Pioneer Venus orbiter. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH31C2746P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH31C2746P">Non-Extensive Statistical Analysis of Solar Wind Electric, Magnetic Fields and Solar Energetic Particle time series.</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pavlos, G. P.; Malandraki, O.; Khabarova, O.; Livadiotis, G.; Pavlos, E.; Karakatsanis, L. P.; Iliopoulos, A. C.; Parisis, K. 2017-12-01 In this work we study the non-extensivity of Solar Wind space plasma by using electric-magnetic field data obtained by in situ spacecraft observations at different dynamical states of solar wind system especially in interplanetary coronal mass ejections (ICMEs), Interplanetary shocks, magnetic islands, or near the Earth Bow shock. Especially, we study the energetic particle non extensive fractional acceleration mechanism producing kappa distributions as well as the intermittent turbulence mechanism producing multifractal structures related with the Tsallis q-entropy principle. We present some new and significant results concerning the dynamics of ICMEs observed in the near Earth at L1 solar wind environment, as well as its effect in Earth's magnetosphere as well as magnetic islands. In-situ measurements of energetic particles at L1 are analyzed, in response to major solar eruptive events at the Sun (intense flares, fast CMEs). The statistical characteristics are obtained and compared for the Solar Energetic Particles (SEPs) originating at the Sun, the energetic particle enhancements associated with local acceleration during the CME-driven shock passage over the spacecraft (Energetic Particle Enhancements, ESPs) as well as the energetic particle signatures observed during the passage of the ICME. The results are referred to Tsallis non-extensive statistics and in particular to the estimation of Tsallis q-triplet, (qstat, qsen, qrel) of electric-magnetic field and the kappa distributions of solar energetic particles time series of the ICME, magnetic islands, resulting from the solar eruptive activity or the internal Solar Wind dynamics. Our results reveal significant differences in statistical and dynamical features, indicating important variations of the magnetic field dynamics both in time and space domains during the shock event, in terms of rate of entropy production, relaxation dynamics and non-equilibrium meta-stable stationary states. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2012V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2012V">Investigation of the variance and spectral anisotropies of the solar wind turbulence with multiple point spacecraft observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Vech, Daniel; Chen, Christopher 2016-04-01 One of the most important features of the plasma turbulence is the anisotropy, which arises due to the presence of the magnetic field. The understanding of the anisotropy is particularly important to reveal how the turbulent cascade operates. It is well known that anisotropy exists with respect to the mean magnetic field, however recent theoretical studies suggested anisotropy with respect to the radial direction. The purpose of this study is to investigate the variance and spectral anisotropies of the solar wind turbulence with multiple point spacecraft observations. The study includes the Advanced Composition Analyzer (ACE), WIND and Cluster spacecraft data. The second order structure functions are derived for two different spacecraft configurations: when the pair of spacecraft are separated radially (with respect to the spacecraft -Sun line) and when they are separated along the transverse direction. We analyze the effect of the different sampling directions on the variance anisotropy, global spectral anisotropy, local 3D spectral anisotropy and discuss the implications for our understanding of solar wind turbulence. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1020869','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1020869">Solar Wind Earth Exchange Project (SWEEP)</a> <a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2016-10-28 AFRL-AFOSR-UK-TR-2016-0035 Solar Wind Earth Exchange Project 140200 Steven Sembay UNIVERSITY OF LEICESTER Final Report 10/28/2016 DISTRIBUTION A...To) 01 Sep 2014 to 31 Aug 2016 4. TITLE AND SUBTITLE Solar Wind Earth Exchange Project (SWEEP) 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-14-1...SUPPLEMENTARY NOTES 14. ABSTRACT The grant received from AFRL/AOFSR/EOARD funded the Solar Wind Earth Exchange Project (SWEEP) at Leicester University. The goal </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740044930&hterms=heinemann&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dheinemann','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740044930&hterms=heinemann&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dheinemann">Shapes of strong shock fronts in an inhomogeneous solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Heinemann, M. A.; Siscoe, G. L. 1974-01-01 The shapes expected for solar-flare-produced strong shock fronts in the solar wind have been calculated, large-scale variations in the ambient medium being taken into account. It has been shown that for reasonable ambient solar wind conditions the mean and the standard deviation of the east-west shock normal angle are in agreement with experimental observations including shocks of all strengths. The results further suggest that near a high-speed stream it is difficult to distinguish between corotating shocks and flare-associated shocks on the basis of the shock normal alone. Although the calculated shapes are outside the range of validity of the linear approximation, these results indicate that the variations in the ambient solar wind may account for large deviations of shock normals from the radial direction. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...859...95A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...859...95A">Dynamics of Intense Currents in the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Artemyev, Anton V.; Angelopoulos, Vassilis; Halekas, Jasper S.; Vinogradov, Alexander A.; Vasko, Ivan Y.; Zelenyi, Lev M. 2018-06-01 Transient currents in the solar wind are carried by various magnetic field discontinuities that contribute significantly to the magnetic field fluctuation spectrum. Internal instabilities and dynamics of these discontinuities are believed to be responsible for magnetic field energy dissipation and corresponding charged particle acceleration and heating. Accurate modeling of these phenomena requires detailed investigation of transient current formation and evolution. By examining such evolution using a unique data set compiled from observations of the same solar wind flow by two spacecraft at Earth’s and Mars’s orbits, we show that it consists of several processes: discontinuity thinning (decrease in thickness normalized by the ion inertial length), intensification of currents normalized to the proton thermal current (i.e., the product of proton charge, density, and thermal velocity), and increase in the compressional component of magnetic field variations across discontinuities. The significant proton temperature variation around most observed discontinuities indicates possible proton heating. Plasma velocity jumps across the discontinuities are well correlated with Alfvén velocity changes. We discuss possible explanations of the observed discontinuity evolution. We also compare the observed evolution with predictions of models describing discontinuity formation due to Alfvén wave steepening. Our results show that discontinuity modeling likely requires taking into account both the effects of nonlinear Alfvén wave dynamics and solar wind expansion. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active">13</li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active">14</li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/575588-solar-wind-eight-proceedings-eighth-international-solar-wind-conference-proceedings','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/575588-solar-wind-eight-proceedings-eighth-international-solar-wind-conference-proceedings">Solar Wind Eight: Proceedings of the Eighth International Solar Wind Conference. Proceedings</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Winterhalter, D.; Gosling, J.T.; Habbal, S.R. 1997-06-01 These proceedings represent papers presented at the eighth international solar wind conference held at the Dana Point Resort, California. The conference was sponsored by the National Aeronautics and Space Administration(NASA), the National Science Foundation(NSF) and the Committee on space Research (COSPAR). The proceedings from this conference reflected the state of the art of solar wind research: its origin at the sun, the transport through the solar system, and its ultimate fate at the heliocentric boundaries. There were one hundred and seventy eight papers presented and nineteen papers for which the research was sponsored by the US Department of Energy havemore » been abstracted for the Energy Science and Technology database.(AIP)« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21700869','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21700869">A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Marty, B; Chaussidon, M; Wiens, R C; Jurewicz, A J G; Burnett, D S 2011-06-24 The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014fysc.confE..27L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014fysc.confE..27L">Chandra Observations of the Solar System</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lisse, Carey 2014-11-01 Many solar system objects are now known to emit X-rays due to charge-exchange between highly charged solar wind (SW) minor ions and neutrals in their extended atmospheres, including Earth, Venus, Mars, Jupiter, and the heliosphere, with total power outputs on the MW - GW scale. (Currently only upper limits exist for Saturn and Pluto.) Chandra observations of their morphology, spectra, and time dependence provide important information about the neutral atmosphere structure and the SW flux and charge state. Chandra observations of solar x-ray scattering from Earth, Venus, Mars, Jupiter, Saturn, and the Moon have also provided important clues for the scattering material and the solar radiation field at the body. We present here a 15 year summary of Chandra's solar system observations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010093223','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010093223">A Study of the Structure of the Source Region of the Solar Wind in Support of a Solar Probe Mission</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Habbal, Shadia R.; Forman, M. A. (Technical Monitor) 2001-01-01 Despite the richness of the information about the physical properties and the structure of the solar wind provided by the Ulysses and SOHO (Solar and Heliospheric Observatory) observations, fundamental questions regarding the nature of the coronal heating mechanisms, their source, and the manifestations of the fast and slow solar wind, still remain unanswered. The last unexplored frontier to establish the connection between the structure and dynamics of the solar atmosphere, its extension into interplanetary space, and the mechanisms responsible for the evolution of the solar wind, is the corona between 1 and 30 R(sub s). A Solar Probe mission offers an unprecedented opportunity to explore this frontier. Its uniqueness stems from its trajectory in a plane perpendicular to the ecliptic which reaches within 9 R(sub s) of the solar 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 detect remnants and signatures of the processes which heat the corona and accelerate the solar wind. In support of this mission, we fulfilled the following two long-term projects: (1) Study of the evolution of waves and turbulence in the solar wind (2) Exploration of signatures of physical processes and structures in the corona. A summary of the tasks achieved in support of these projects are given below. In addition, funds were provided to support the Solar Wind 9 International Conference which was held in October 1998. A brief report on the conference is also described in what follows. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..119.7120J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..119.7120J">Comparison of interplanetary CME arrival times and solar wind parameters based on the WSA-ENLIL model with three cone types and observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jang, Soojeong; Moon, Y.-J.; Lee, Jae-Ok; Na, Hyeonock 2014-09-01 We have made a comparison between coronal mass ejection (CME)-associated shock propagations based on the Wang-Sheeley-Arge (WSA)-ENLIL model using three cone types and in situ observations. For this we use 28 full-halo CMEs, whose cone parameters are determined and their corresponding interplanetary shocks were observed at the Earth, from 2001 to 2002. We consider three different cone types (an asymmetric cone model, an ice cream cone model, and an elliptical cone model) to determine 3-D CME cone parameters (radial velocity, angular width, and source location), which are the input values of the WSA-ENLIL model. The mean absolute error of the CME-associated shock travel times for the WSA-ENLIL model using the ice-cream cone model is 9.9 h, which is about 1 h smaller than those of the other models. We compare the peak values and profiles of solar wind parameters (speed and density) with in situ observations. We find that the root-mean-square errors of solar wind peak speed and density for the ice cream and asymmetric cone model are about 190 km/s and 24/cm3, respectively. We estimate the cross correlations between the models and observations within the time lag of ± 2 days from the shock travel time. The correlation coefficients between the solar wind speeds from the WSA-ENLIL model using three cone types and in situ observations are approximately 0.7, which is larger than those of solar wind density (cc ˜0.6). Our preliminary investigations show that the ice cream cone model seems to be better than the other cone models in terms of the input parameters of the WSA-ENLIL model. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021320&hterms=imprint&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dimprint','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021320&hterms=imprint&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dimprint">Evidence of active region imprints on the solar wind structure</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hick, P.; Jackson, B. V. 1995-01-01 A common descriptive framework for discussing the solar wind structure in the inner heliosphere uses the global magnetic field as a reference: low density, high velocity solar wind emanates from open magnetic fields, with high density, low speed solar wind flowing outward near the current sheet. In this picture, active regions, underlying closed magnetic field structures in the streamer belt, leave little or no imprint on the solar wind. We present evidence from interplanetary scintillation measurements of the 'disturbance factor' g that active regions play a role in modulating the solar wind and possibly contribute to the solar wind mass output. Hence we find that the traditional view of the solar wind, though useful in understanding many features of solar wind structure, is oversimplified and possibly neglects important aspects of solar wind dynamics </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110023419&hterms=geomagnetic+reversal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeomagnetic%2Breversal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110023419&hterms=geomagnetic+reversal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeomagnetic%2Breversal">Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Emery, Barbara A.; Richardson, Ian G.; Evans, David S.; Rich, Frederick J.; Wilson, Gordon R. 2011-01-01 The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar 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 solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar 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 solar 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 solar wind-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 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5261766-solar-wind-speed-he-nm-absorption-line-intensity','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5261766-solar-wind-speed-he-nm-absorption-line-intensity">Solar wind speed and He I (1083 nm) absorption line intensity</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hakamada, Kazuyuki; Kojima, Masayoshi; Kakinuma, Takakiyo 1991-04-01 Since the pattern of the solar wind was relatively steady during Carrington rotations 1,748 through 1,752 in 1984, an average distribution of the solar windspeed on a so-called source surface can be constructed by superposed epoch analysis of the wind values estimated by the interplanetary scintillation observations. The average distribution of the solar wind speed is then projected onto the photosphere along magnetic field lines computed by a so-called potential model with the line-of-sight components of the photospheric magnetic fields. The solar wind speeds projected onto the photosphere are compared with the intensities of the He I (1,083 nm) absorptionmore » line at the corresponding locations in the chromosphere. The authors found that there is a linear relation between the speeds and the intensities. Since the intensity of the He I (1,083 nm) absorption line is coupled with the temperature of the corona, this relation suggests that some physical mechanism in or above the photosphere accelerates coronal plasmas to the solar wind speed in regions where the temperature is low. Further, it is suggested that the efficiency of the solar wind acceleration decreases as the coronal temperature increases.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021447&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D20%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021447&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D20%26Ntt%3Dlazarus">Solar wind plasma periodicities observed at 1 AU by IMP 8</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Paularena, K. I.; Szabo, A.; Lazarus, A. J. 1995-01-01 The IMP 8 spacecraft has been in Earth orbit since 1973, gathering plasma data over one complete 22-year solar cycle. These data are being examined to look for periodicities at time scales ranging from several hours to the entire span of the data set. A 1.3-year periodicity in the radial speed observed by IMP 8 and Voyager 2 has already been reported for the years from 1987 to 1993. The periodogram method, useful for unevenly sampled data such as the IMP 8 plasma data, has been used to search for other periods. It is interesting to note that the 13-year period is not present in the out-of-the-ecliptic component of the velocity (Vz), although a 1-year period is very obvious both visually and on the periodogram. Both components show a very strong peak associated with the 11-year solar cycle variation. This work will be extended to the thermal speed (a measure of the wind's temperature) and density, although the frequent correlations between these parameters and the velocity are expected to cause similar results. Additionally, the fine resolution data will be examined for shorter time periods than are visible using the hourly average data which are appropriate for longer periods. A comparison with periods observed at other spacecraft may also be made. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007840','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007840">A Model for the Sources of the Slow Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Antiochos, Spiro K.; Mikic, Z.; Titov, V. S.; Lionello, R.; Linker, J. A. 2010-01-01 Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind 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 wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far 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 solar wind and magnetic field for a time period preceding the August 1, 2008 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere, and propose further tests of the model. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ApJ...731..112A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ApJ...731..112A">A Model for the Sources of the Slow Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Antiochos, S. K.; Mikić, Z.; Titov, V. S.; Lionello, R.; Linker, J. A. 2011-04-01 Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to ~60°, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind, and magnetic field for a time period preceding the 2008 August 1 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere and propose further tests of the model. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730002035','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730002035">Coronal magnetic fields and the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Newkirk, G., Jr. 1972-01-01 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...832...66E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...832...66E">Long-term Trends in the Solar Wind Proton Measurements</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Elliott, Heather A.; McComas, David J.; DeForest, Craig E. 2016-11-01 We examine the long-term time evolution (1965-2015) of the relationships between solar wind proton temperature (T p) and speed (V p) and between the proton density (n p) and speed using OMNI solar wind observations taken near Earth. We find a long-term decrease in the proton temperature-speed (T p-V p) slope that lasted from 1972 to 2010, but has been trending upward since 2010. Since the solar wind proton density-speed (n p-V p) relationship is not linear like the T p-V p relationship, we perform power-law fits for n p-V p. The exponent (steepness in the n p-V p relationship) is correlated with the solar cycle. This exponent has a stronger correlation with current sheet tilt angle than with sunspot number because the sunspot number maxima vary considerably from cycle to cycle and the tilt angle maxima do not. To understand this finding, we examined the average n p for different speed ranges, and found that for the slow wind n p is highly correlated with the sunspot number, with a lag of approximately four years. The fast wind n p variation was less, but in phase with the cycle. This phase difference may contribute to the n p-V p exponent correlation with the solar cycle. These long-term trends are important since empirical formulas based on fits to T p and V p data are commonly used to identify interplanetary coronal mass ejections, but these formulas do not include any time dependence. Changes in the solar wind density over a solar cycle will create corresponding changes in the near-Earth space environment and the overall extent of the heliosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110013445&hterms=parametric+scaling&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dparametric%2Bscaling','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110013445&hterms=parametric+scaling&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dparametric%2Bscaling">Hybrid Model of Inhomogeneous Solar Wind Plasma Heating by Alfven Wave Spectrum: Parametric Studies</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ofman, L. 2010-01-01 Observations of the solar wind plasma at 0.3 AU and beyond show that a turbulent spectrum of magnetic fluctuations is present. Remote sensing observations of the corona indicate that heavy ions are hotter than protons and their temperature is anisotropic (T(sub perpindicular / T(sub parallel) >> 1). We study the heating and the acceleration of multi-ion plasma in the solar wind by a turbulent spectrum of Alfvenic fluctuations using a 2-D hybrid numerical model. In the hybrid model the protons and heavy ions are treated kinetically as particles, while the electrons are included as neutralizing background fluid. This is the first two-dimensional hybrid parametric study of the solar wind plasma that includes an input turbulent wave spectrum guided by observation with inhomogeneous background density. We also investigate the effects of He++ ion beams in the inhomogeneous background plasma density on the heating of the solar wind plasma. The 2-D hybrid model treats parallel and oblique waves, together with cross-field inhomogeneity, self-consistently. We investigate the parametric dependence of the perpendicular heating, and the temperature anisotropy in the H+-He++ solar wind plasma. It was found that the scaling of the magnetic fluctuations power spectrum steepens in the higher-density regions, and the heating is channeled to these regions from the surrounding lower-density plasma due to wave refraction. The model parameters are applicable to the expected solar wind conditions at about 10 solar radii. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830033900&hterms=overcoming+bias&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dovercoming%2Bbias','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830033900&hterms=overcoming+bias&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dovercoming%2Bbias">Measurements of the properties of solar wind plasma relevant to studies of its coronal sources</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Neugebauer, M. 1982-01-01 Interplanetary measurements of the speeds, densities, abundances, and charge states of solar wind ions are diagnostic of conditions in the source region of the solar wind. The absolute values of the mass, momentum, and energy fluxes in the solar wind are not known to an accuracy of 20%. The principal limitations on the absolute accuracies of observations of solar wind protons and alpha particles arise from uncertain instrument calibrations, from the methods used to reduce the data, and from sampling biases. Sampling biases are very important in studies of alpha particles. Instrumental resolution and measurement ambiguities are additional major problems for the observation of ions heavier than helium. Progress in overcoming some of these measurement inadequacies is reviewed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010032395','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010032395">Acceleration of the Fast Solar Wind by Solitary Waves in Coronal Holes</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ofman, Leon 2001-01-01 The purpose of this investigation is to develop a new model for the acceleration of the fast solar wind by nonlinear. time-dependent multidimensional MHD simulations of waves in solar coronal holes. Preliminary computational studies indicate that nonlinear waves are generated in coronal holes by torsional Alfv\\'{e}n waves. These waves in addition to thermal conduction may contribute considerably to the accelerate the solar wind. Specific goals of this proposal are to investigate the generation of nonlinear solitary-like waves and their effect on solar wind acceleration by numerical 2.5D MHD simulation of coronal holes with a broad range of plasma and wave parameters; to study the effect of random disturbances at the base of a solar coronal hole on the fast solar wind acceleration with a more advanced 2.5D MHD model and to compare the results with the available observations; to extend the study to a full 3D MHD simulation of fast solar wind acceleration with a more realistic model of a coronal hole and solar boundary conditions. The ultimate goal of the three year study is to model the, fast solar wind in a coronal hole, based on realistic boundary conditions in a coronal hole near the Sun, and the coronal hole structure (i.e., density, temperature. and magnetic field geometry,) that will become available from the recently launched SOHO spacecraft. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000021483','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000021483">Acceleration of the Fast Solar Wind by Solitary Waves in Coronal Holes</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ofman, Leon 2000-01-01 The purpose of this investigation is to develop a new model for the acceleration of the fast solar wind by nonlinear, time-dependent multidimensional MHD simulations of waves in solar coronal holes. Preliminary computational studies indicate that solitary-like waves are generated in coronal holes nonlinearly by torsional Alfven waves. These waves in addition to thermal conduction may contribute considerably to the accelerate the solar wind. Specific goals of this proposal are to investigate the generation of nonlinear solitary-like waves and their effect on solar wind acceleration by numerical 2.5D MHD simulation of coronal holes with a broad range of plasma and wave parameters; to study the effect of random disturbances at the base of a solar coronal hole on the fast solar wind acceleration with a more advanced 2.5D MHD model and to compare the results with the available observations; to extend the study to a full 3D MHD simulation of fast solar wind acceleration with a more realistic model of a coronal hole and solar boundary conditions. The ultimate goal of the three year study is to model the fast solar wind in a coronal hole, based on realistic boundary conditions in a coronal hole near the Sun, and the coronal hole structure (i.e., density, temperature, and magnetic field geometry) that will become available from the recently launched SOHO spacecraft. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123...20B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123...20B">On the Origins of the Intercorrelations Between Solar Wind Variables</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Borovsky, Joseph E. 2018-01-01 It is well known that the time variations of the diverse solar wind variables at 1 AU (e.g., solar wind speed, density, proton temperature, electron temperature, magnetic field strength, specific entropy, heavy-ion charge-state densities, and electron strahl intensity) are highly intercorrelated with each other. In correlation studies of the driving of the Earth's magnetosphere-ionosphere-thermosphere system by the solar wind, these solar wind intercorrelations make determining cause and effect very difficult. In this report analyses of solar wind spacecraft measurements and compressible-fluid computer simulations are used to study the origins of the solar wind intercorrelations. Two causes are found: (1) synchronized changes in the values of the solar wind variables as the plasma types of the solar wind are switched by solar rotation and (2) dynamic interactions (compressions and rarefactions) in the solar wind between the Sun and the Earth. These findings provide an incremental increase in the understanding of how the Sun-Earth system operates. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021450&hterms=exact+solutions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dexact%2Bsolutions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021450&hterms=exact+solutions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dexact%2Bsolutions">Modeling the heliolatitudinal gradient of the solar wind parameters with exact MHD solutions</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lima, J. J. G.; Tsinganos, K. 1995-01-01 The heliolatitudinal dependence of observations of the solar wind macroscopic quantities such as the averaged proton speed, density and the mass and momentum flux are modeled. The published observations covering the last two and a half solar cycles, are obtained either via the technique of interplanetary scintillations for the last 2 solar cycles (1970-1990), or, from the plasma experiment aboard the ULYSSES spacecraft for the recent period 1990-1994. Exact, two dimensional solutions of the full set of the steady MHD equations are used which are obtained through a nonlinear separation of the variables in the MHD equations. The three parameters emerging from the solutions are fixed from these observations, as well as from observations of the solar rotation. It is found that near solar maximum the solar wind speed is uniformly low, around the 400 km/s over a wide range of latitudes. On the other hand, during solar minimum and the declining phase of the solar activity cycle, there is a strong heliolatitudinal gradient in proton speed between 400-800 from equator to pole. This modeling also agrees with previous findings that the gradient in wind speed with the latitude is offset by a gradient in density such that the mass and momentum flux vary relatively little. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060036154&hterms=dependency&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddependency','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060036154&hterms=dependency&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddependency">(abstract) Ulysses Solar Wind Ion Temperatures: Radial, Latitudinal, and Dynamical Dependencies</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Goldstein, B. E.; Smith, E. J.; Gosling, J. T.; McComas, D. J.; Balogh, A. 1996-01-01 Observations of the Ulysses SWOOPS plasma experiment are used to determine the dependencies of solar wind ion temperatures upon radial distance, speed, and other parameters, and to estimate solar wind heating. Comparisons with three dimensional temperature estimates determined from the ion spectra by a least squares fitting program will be provided (only small samples of data have been reduced with this program). </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active">14</li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active">15</li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012MNRAS.421..943K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012MNRAS.421..943K">Solar wind and the motion of dust grains</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Klačka, J.; Petržala, J.; Pástor, P.; Kómar, L. 2012-04-01 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840005021','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840005021">Solar cycle variations of the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Crooker, N. U. 1983-01-01 Throughout the course of the past one and a half solar cycles, solar wind parameters measured near the ecliptic plane at 1 AU varied in the following way: speed and proton temperature have maxima during the declining phase and minima at solar minimum and are approximately anti-correlated with number density and electron temperature, while magnetic field magnitude and relative abundance of helium roughly follow the sunspot cycle. These variations are described in terms of the solar cycle variations of coronal holes, streamers, and transients. The solar wind signatures of the three features are discussed in turn, with special emphasis on the signature of transients, which is still in the process of being defined. It is proposed that magnetic clouds be identified with helium abundance enhancements and that they form the head of a transient surrounded by streamer like plasma, with an optional shock front. It is stressed that relative values of a parameter through a solar cycle should be compared beginning with the declining phase, especially in the case of magnetic field magnitude. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760033224&hterms=methane+composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmethane%2Bcomposition','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760033224&hterms=methane+composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmethane%2Bcomposition">Solar-wind interactions - Nature and composition of lunar atmosphere</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Mukherjee, N. R. 1975-01-01 The nature and composition of the lunar atmosphere are examined on the basis of solar-wind interactions, and the nature of the species in the trapped-gas layer is discussed using results of theoretical and experimental investigations. It is shown that the moon has a highly tenuous atmosphere consisting of various species derived from five sources: solar-wind interaction products, cosmic-ray interaction products, effects of meteoritic impacts, planetary degassing, and radioactive-decay products. Atmospheric concentrations are determined for those species derived from solar-wind protons, alpha particles, and oxygen ions. Carbon chemistry is briefly discussed, and difficulties encountered in attempts to determine quantitatively the concentrations of molecular oxygen, atomic oxygen, carbon monoxide, carbon dioxide, and methane are noted. The calculated concentrations are shown to be in good agreement with observations by the Apollo 17 lunar-surface mass spectrometer and orbital UV spectrometer. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...850...45R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...850...45R">Global Solar Magnetic Field Organization in the Outer Corona: Influence on the Solar Wind Speed and Mass Flux Over the Cycle</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Réville, Victor; Brun, Allan Sacha 2017-11-01 The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11-year solar cycle. For instance, the wind terminal velocity is thought to be anti-correlated with the expansion factor, a measure of how the magnetic field varies with height in the solar corona, usually computed at a fixed height (≈ 2.5 {R}⊙ , the source surface radius that approximates the distance at which all magnetic field lines become open). However, the magnetic field expansion affects the solar wind in a more detailed way, its influence on the solar wind properties remaining significant well beyond the source surface. We demonstrate this using 3D global magnetohydrodynamic (MHD) simulations of the solar corona, constrained by surface magnetograms over half a solar cycle (1989-2001). A self-consistent expansion beyond the solar wind critical point (even up to 10 {R}⊙ ) makes our model comply with observed characteristics of the solar wind, namely, that the radial magnetic field intensity becomes latitude independent at some distance from the Sun, and that the mass flux is mostly independent of the terminal wind speed. We also show that near activity minimum, the expansion in the higher corona has more influence on the wind speed than the expansion below 2.5 {R}⊙ . </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.nrel.gov/grid/wwsis.html','SCIGOVWS'); return false;" href="https://www.nrel.gov/grid/wwsis.html">Western Wind and Solar Integration Study | Grid Modernization | NREL</a> <a target="_blank" href="http://www.science.gov/aboutsearch.html">Science.gov Websites</a> Western Wind and Solar Integration Study Western Wind and Solar Integration Study Can we integrate large amounts of wind and solar energy into the electric power system of the West? That's the question explored by the Western Wind and Solar Integration Study, one of the largest such regional studies to date </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000DPS....32.4701L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000DPS....32.4701L">Venus and Mars Obstacles in the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Luhmann, J. G.; Mitchell, D. L.; Acuna, M. H.; Russell, C. T.; Brecht, S. H.; Lyon, J. G. 2000-10-01 Comparisons of the magnetosheaths of Venus and Mars contrast the relative simplicity of the Venus solar wind interaction and the ``Jekyll and Hyde" nature of the Mars interaction. Magnetometer observations from Mars Global Surveyor during the elliptical science phasing orbits and Pioneer Venus Orbiter in its normally elliptical orbit are compared, with various models used to compensate for the different near-polar periapsis of MGS and near-equator periapsis of PVO. Gasdynamic or MHD fluid models of flow around a conducting sphere provide a remarkably good desciption of the Venus case, and the Mars case when the strong Martian crustal magnetic anomalies are in the flow wake. In the case of Venus, large magnetosheath field fluctuations can be reliably tied to occurrence of a subsolar quasiparallel bow shock resulting from a small interplanetary field cone angle (angle between flow and field) upstream. At Mars one must also contend with such large fluctuations from the bow shock, but also from unstable solar wind proton distributions due to finite ion gyroradius effects, and from the complicated obstacle presented to the solar wind when the crustal magnetic anomalies are on the ram face or terminator. We attempt to distinguish between these factors at Mars, which are important for interpretation of the upcoming NOZOMI and Mars Express mission measurements. The results also provide more insights into a uniquely complex type of solar system solar wind interaction involving crustal fields akin to the Moon's, combined with a Venus-like ionospheric obstacle. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900027052&hterms=Fran&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DFran','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900027052&hterms=Fran&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DFran">Pluto's interaction with the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bagenal, Fran; Mcnutt, Ralph L., Jr. 1989-01-01 If Pluto's atmospheric escape rate is significantly greater than 1.5 x 10 to the 27th molecules/s then the interaction with the tenuous solar wind at 30 A.U. will be like that of a comet. There will be extensive ion pick-up upstream and the size of the interaction region will vary directly with variations in the solar wind flux. If the escape flux is much less, then one expects that the solar wind will be deflected around Pluto's ionosphere in a Venus-like interaction. In either case, the weak interplanetary magnetic field at 30 A.U. results in very large gyroradii for the picked-up ions and a thick bow shock, necessitating a kinetic treatment of the interaction. Strong variations in the size of the interaction region are expected on time scales of days due to changes in the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018LPICo2047.6014F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018LPICo2047.6014F">Getting Ready for BepiColombo: A Modeling Approach to Infer the Solar Wind Plasma Parameters Upstream of Mercury from Magnetic Field Observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Fatemi, S.; Poirier, N.; Holmström, M.; Wieser, M.; Barabash, S. 2018-05-01 We have developed a model to infer the solar wind plasma parameters upstream of Mercury from magnetic field observations in Mercury's magnetosphere. This is important for observations by MESSENGER and the future mission to Mercury, BepiColombo. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760017040','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760017040">The large-scale magnetic field in the solar wind. [astronomical models of interplanetary magnetics and the solar magnetic field</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Burlaga, L. F.; Ness, N. F. 1976-01-01 A literature review is presented of theoretical models of the interaction of the solar wind and interplanetary magnetic fields. Observations of interplanetary magnetic fields by the IMP and OSO spacecraft are discussed. The causes for cosmic ray variations (Forbush decreases) by the solar wind are examined. The model of Parker is emphasized. This model shows the three dimensional magnetic field lines of the solar wind to have the form of spirals wrapped on cones. It is concluded that an out-of-the-ecliptic solar probe mission would allow the testing and verification of the various theoretical models examined. Diagrams of the various models are shown. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070010017&hterms=Accounting+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DAccounting%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070010017&hterms=Accounting+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DAccounting%2Bmeasurement">Physics-based Tests to Identify the Accuracy of Solar Wind Ion Measurements: A Case Study with the Wind Faraday Cups</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kasper, J. C.; Lazarus, A. J.; Steinberg, J. T.; Ogilvie, K. W.; Szabo, A. 2006-01-01 We present techniques for comparing measurements of velocity, temperature, and density with constraints imposed by the plasma physics of magnetized bi-Maxwellian ions. Deviations from these physics-based constraints are interpreted as arising from measurement errors. Two million ion spectra from the Solar Wind Experiment Faraday Cup instruments on the Wind spacecraft are used as a case study. The accuracy of velocity measurements is determined by the fact that differential flow between hydrogen and helium should be aligned with the ambient magnetic field. Modeling the breakdown of field alignment suggests velocity uncertainties are less than 0.16% in magnitude and 3deg in direction. Temperature uncertainty is found by examining the distribution of observed temperature anisotropies in high-beta solar wind intervals where the firehose, mirror, and cyclotron microinstabilities should drive the distribution to isotropy. The presence of a finite anisotropy at high beta suggests overall temperature uncertainties of 8%. Hydrogen and helium number densities are compared with the electron density inferred from observations of the local electron plasma frequency as a function of solar wind speed and year. We find that after accounting for the contribution of minor ions, the results are consistent with a systematic offset between the two instruments of 34%. The temperature and density methods are sensitive to non-Maxwellian features such as heat flux and proton beams and as a result are more suited to slow solar wind where these features are rare. These procedures are of general use in identifying the accuracy of observations from any solar wind ion instrument. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUSMSH34B..03C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUSMSH34B..03C">Turbulence and Waves as Sources for the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cranmer, S. R. 2008-05-01 Gene Parker's insights from 50 years ago provided the key causal link between energy deposition in the solar corona and the acceleration of solar wind streams. However, the community is still far from agreement concerning the actual physical processes that give rise to this energy. It is still unknown whether the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy is input more intermittently from closed loops into the open-field regions. No matter the relative importance of reconnections and loop-openings, though, we do know that waves and turbulent motions are present everywhere from the photosphere to the heliosphere, and it is important to determine how they affect the mean state of the plasma. In this presentation, I will give a summary of wave/turbulence models that seem to succeed in explaining the time-steady properties of the corona (and the fast and slow solar wind). The coronal heating and solar wind acceleration in these models comes from anisotropic turbulent cascade, which is driven by the partial reflection of low-frequency Alfven waves propagating along the open magnetic flux tubes. Specifically, a 2D model of coronal holes and streamers at solar minimum reproduces the latitudinal bifurcation of slow and fast streams seen by Ulysses. The radial gradient of the Alfven speed affects where the waves are reflected and damped, and thus whether energy is deposited below or above Parker's critical point. As predicted by earlier studies, a larger coronal expansion factor gives rise to a slower and denser wind, higher temperature at the coronal base, less intense Alfven waves at 1 AU, and correlative trends for commonly measured ratios of ion charge states and FIP-sensitive abundances that are in general agreement with observations. Finally, I will outline the types of future observations that would be most able to test and refine these ideas. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1011062','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1011062">Modeling the Magnetospheric X-ray Emission from Solar Wind Charge Exchange with Verification from XMM-Newton Observations</a> <a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2016-08-26 Journal of Geophysical Research: Space Physics Modeling the magnetospheric X-ray emission from solar wind charge exchange with verification from XMM...Newton observations Ian C. Whittaker1, Steve Sembay1, Jennifer A. Carter1, AndrewM. Read1, Steve E. Milan1, andMinna Palmroth2 1Department of Physics ...observations, J. Geophys. Res. Space Physics , 121, 4158–4179, doi:10.1002/2015JA022292. Received 21 DEC 2015 Accepted 26 FEB 2016 Accepted article online 29 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1224824','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1224824">Solar energy system with wind vane</a> <a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a> Grip, Robert E 2015-11-03 A solar energy system including a pedestal defining a longitudinal axis, a frame that is supported by the pedestal and that is rotateable relative to the pedestal about the longitudinal axis, the frame including at least one solar device, and a wind vane operatively connected to the frame to urge the frame relative to the pedestal about the longitudinal axis in response to wind acting on the wind vane. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982STIN...8233887E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982STIN...8233887E">Solar- and wind-powered irrigation systems</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Enochian, R. V. 1982-02-01 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 in remote areas where adequate wind is available. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170006116&hterms=electromagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Delectromagnetic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170006116&hterms=electromagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Delectromagnetic">Electromagnetic Cyclotron Waves in the Solar Wind: Wind Observation and Wave Dispersion Analysis</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Jian, L. K.; Moya, P. S.; Vinas, A. F.; Stevens, M. 2016-01-01 Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and alpha-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22590907-electromagnetic-cyclotron-waves-solar-wind-wind-observation-wave-dispersion-analysis','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22590907-electromagnetic-cyclotron-waves-solar-wind-wind-observation-wave-dispersion-analysis">Electromagnetic cyclotron waves in the solar wind: Wind observation and wave dispersion analysis</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Jian, L. K., E-mail: lan.jian@nasa.gov; Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771; Moya, P. S. 2016-03-25 Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and α-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130012782','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130012782">Construction of Solar-Wind-Like Magnetic Fields</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Roberts, Dana Aaron 2012-01-01 Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfven waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This paper 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 solar wind, 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 solar wind turbulence and of the propagation of energetic particles. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090006612&hterms=Solar+still&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSolar%2Bstill','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090006612&hterms=Solar+still&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSolar%2Bstill">Topological Origins of the Slow Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Antiochos, Spiro 2008-01-01 Although the slow solar wind has been studied for decades with both in situ and remote sensing observations, its origin is still a matter of intense debate. In the standard quasi-steady model, the slow wind is postulated to originate near coronal hole boundaries that define topologically well-behaved separatrices between open and closed field regions. In the interchange model, on the other hand, the slow wind is postulated to originate on open flux that is dynamically diffusing throughout the seemingly closed-field corona. We argue in favor of the quasi-steady scenario and propose that the slow wind is due to two effects: First, the open-closed boundary is highly complex due to the complexity of the photospheric flux distribution. Second, this boundary is continuously driven by the transport of magnetic helicity from the closed field region into the open. The implications of this model for the structure and dynamics of the corona and slow wind are discussed, and observational tests of the mode </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22590905-fip-effect-minor-heavy-solar-wind-ions-seen-soho-celias-mtof','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22590905-fip-effect-minor-heavy-solar-wind-ions-seen-soho-celias-mtof">FIP effect for minor heavy solar wind ions as seen with SOHO/CELIAS/MTOF</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Heidrich-Meisner, Verena, E-mail: heidrich@physik.uni-kiel.de; Berger, Lars; Wimmer-Schweingruber, Robert F. A recent paper [Shearer et al., 2014] reported that during solar maximum Ne showed a surprisingly low abundance. This leads to the question whether other elements show the same behavior. The good mass resolution of Mass-Time-Of-Flight (MTOF) as part of the Charge ELement and Isotope Analysis System (CELIAS) on the Solar Helioshperic Observatory (SOHO) allows to investigate the composition of heavy minor elements in different types of solar wind. We restrict this study to slow solar wind, where the characterisation of slow solar wind is taken from Xu and Borovsky, 2014. This classification scheme requires magnet field information. Since SOHOmore » does not carry a magnetometer, we use the Magnetometer (MAG) of the Advanced Composition Explorer (ACE) instead. The Solar Wind Ion Composition Spectrometer (ACE/SWICS) also provides composition data for cross-calibration and charge-state distributions as input for the transmission function of MTOF whenever the two spacecraft can be expected to observe the same type of wind. We illustrate the MTOF’s capability to determine the solar wind abundance compared to the photospheric abundance (called the FIP ratio in the following) for rare elements like Ti or Cr on long-time scales as a proof of concept for our analysis. And in this brief study, measurements with both ACE/SWICS indicate that the observed elements exhibit a (weak) dependence on the solar cycle, whereas the MTOF measurements are inconclusive.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000092430&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000092430&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwind%2Bmonitor">The Interaction of Solar wind Discontinuities with the Earth's Bow Shock</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sibeck, David G. 2000-01-01 Funding from NASA Grant No. NAG54679 was received in three installments. The first year's installment amounted to only one month of salary support and was used to prepare survey plots. The second year's installment allowed us to complete two research papers concerning the interaction of solar wind discontinuities with the Earth's bow shock. In the first (published) paper, we reported that the discontinuities launch slow mode waves into the magnetosheath and the slow mode waves always propagate antisunward through the flank magnetosheath. Because the sunward/antisunward sense of the magnetosheath magnetic field reverses across local noon, so does the (north/south or east/west) sense of the velocity fluctuations associated with the waves. Wind, Geotail, and IMP-8 observations were used for this study. In the second study, we used Wind and Interball-1 observations to demonstrate that pressure pulses in the magnetosheath occur in pairs and that they bound pressure cavities and/or brief intervals of outward magnetopause motion. This paper is now in press. Funding from the third year's installment has been used to investigate the two aspects of the foreshock. Two manuscripts are now in preparation for submission to the Journal of Geophysical Research. The first reports that waves within the foreshock account for many instances of poor correlations between two solar wind monitors. Remaining cases of poor correlation occur during intervals of nearly constant IMF orientations and magnetic field strengths. While the former category pose a significant difficulty for space weather forecasts, the latter do not. The second study surveys IMP-8 observations of the foreshock. We find that diamagnetic cavities are common, particularly during periods of high solar wind velocity and low solar wind density. Plasma densities, temperatures, and magnetic field strengths fall during intervals of enhanced energetic particle fluxes. The cavities are bounded by regions of decelerated solar </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active">15</li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active">16</li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFMSH21A0473S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFMSH21A0473S">ICME Identification from Solar Wind Ion Measurements</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shinde, A.; Russell, C. T. 2002-12-01 In the solar corona, coronal mass ejections are generally identified as an outward moving density enhancement. At 1AU their interplanetary counterparts are generally identified as a twisted and enhanced magnetic structures lasting of the order of a day. In an effort to better classify ICMEs we attempt herein to identify their start and stop time by their signatures in ion data obtained by Wind and ACE solar wind instruments. We search for periods in which the solar wind speed is linearly decreasing and the ion temperature is cool, with a thermal speed of less than 20 km/s. We required a simultaneous enhanced magnetic field but required no special signature of this enhancement. We compared these identifications with those made by D. Larson and R. P. Lepping and published on the web. Of 14 events, 4 were not identified as ICMEs by either Larson or Lepping. Similarly they identified many events that we did not, often because the ion temperature was above our classification threshold, but also because there was no clear speed decrease as the event crossed the spacecraft as would signal an expanding structure. The best events in Larson and Lepping's list had a rate of speed decrease that, if due to the expansion of the structure with distance from the sun moving at the average observed speed, would bring the structure from zero width to the present size in its calculated transit time. We conclude that cold ion temperatures and a declining solar wind velocity are frequent ICME signatures but are neither necessary nor sufficient for ICME identification. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21568542','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21568542">Systematic measurements of ion-proton differential streaming in the solar wind.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Berger, L; Wimmer-Schweingruber, R F; Gloeckler, G 2011-04-15 The small amount of heavy ions in the highly rarefied solar wind are sensitive tracers for plasma-physics processes, which are usually not accessible in the laboratory. We have analyzed differential streaming between heavy ions and protons in the solar wind at 1 AU. 3D velocity vector and magnetic field measurements from the Solar Wind Electron Proton Alpha Monitor and the Magnetometer aboard the Advanced Composition Explorer were used to reconstruct the ion-proton difference vector v(ip) = v(i) - v(p) from the 12 min 1D Solar Wind Ion Composition Spectrometer observations. We find that all 44 analyzed heavy ions flow along the interplanetary magnetic field at velocities which are smaller than, but comparable to, the local Alfvén speed C(A). The flow speeds of 35 of the 44 ion species lie within the range of ±0.15C(A) around 0.55C(A), the flow speed of He(2+). </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.9237H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.9237H">A multi-timescale view on the slow solar wind with MTOF</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Heidrich-Meisner, Verena; Wimmer-Schweingruber, Robert F.; Wurz, Peter; Bochsler, Peter; Ipavich, Fred M.; Paquette, John A.; Klecker, Bernard 2013-04-01 leads to an extensive picture of individual streams from MTOF, which can be combined with observations from other spacecraft in the future. In particular, identifying and understanding short-term variations of the slow solar wind has the potential to help distinguishing between different possible source regions and mechanisms. Further, with the long term goal of identifying possible different source mechanisms or regions, we analyze and compare the properties of individual streams on short time scales to focus on significant deviations from the average properties of slow solar wind. References [Antiochos2011] SK Antiochos, Z. Mikic, VS Titov, R. Lionello, and JA Linker. A model for the sources of the slow solar wind. The Astrophysical Journal, 731(2):112, 2011. [Hovestadt1995] D. Hovestadt, M. Hilchenbach, A. Bürgi, B. Klecker, P. Laeverenz, M. Scholer, H. Grünwaldt, WI Axford, S. Livi, E. Marsch, et al. Celias-charge, element and isotope analysis system for soho. Solar Physics, 162(1):441-481, 1995. [Pagel2004] AC Pagel, NU Crooker, TH Zurbuchen, and JT Gosling. Correlation of solar wind entropy and oxygen ion charge state ratio. Journal of geophysical research, 109(A1):A01113, 2004. [Sakao2007] T. Sakao, R. Kano, N. Narukage, J. Kotoku, T. Bando, E.E. DeLuca, L.L. Lundquist, S. Tsuneta, L.K. Harra, Y. Katsukawa, et al. Continuous plasma outflows from the edge of a solar active region as a possible source of solar wind. Science, 318(5856):1585-1588, 2007. [Schwadron2005] NA Schwadron, DJ McComas, HA Elliott, G. Gloeckler, J. Geiss, and R. Von Steiger. Solar wind from the coronal hole boundaries. Journal of geophysical research, 110(A4):A04104, 2005. [Tu2005] C.Y. Tu, C. Zhou, E. Marsch, L.D. Xia, L. Zhao, J.X. Wang, and K. Wilhelm. Solar wind origin in coronal funnels. Science, 308(5721):519-523, 2005. [vonSteiger2000] R. Von Steiger, N. Schwadron, LA Fisk, J. Geiss, G. Gloeckler, S. Hefti, B. Wilken, RF Wimmer-Schweingruber, and TH Zurbuchen. Composition of quasi </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMSH41B1786C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMSH41B1786C">Recent Successes of Wave/Turbulence Driven Models of Solar Wind Acceleration</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cranmer, S. R.; Hollweg, J. V.; Chandran, B. D.; van Ballegooijen, A. A. 2010-12-01 A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a first-principles understanding of coronal heating. Also, it is still unknown whether the solar wind is "fed" through flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy are input intermittently from closed loops into the open-field regions. In this presentation, we discuss self-consistent models that assume the energy comes from solar Alfven waves that are partially reflected, and then dissipated, by magnetohydrodynamic turbulence. These models have been found to reproduce many of the observed features of the fast and slow solar wind without the need for artificial "coronal heating functions" used by earlier models. For example, the models predict a variation with wind speed in commonly measured ratios of charge states and elemental abundances that agrees with observed trends. This contradicts a commonly held assertion that these ratios can only be produced by the injection of plasma from closed-field regions on the Sun. This presentation also reviews two recent comparisons between the models and empirical measurements: (1) The models successfully predict the amplitude and radial dependence of Faraday rotation fluctuations (FRFs) measured by the Helios probes for heliocentric distances between 2 and 15 solar radii. The FRFs are a particularly sensitive test of turbulence models because they depend not only on the plasma density and Alfven wave amplitude in the corona, but also on the turbulent correlation length. (2) The models predict the correct sense and magnitude of changes seen in the polar high-speed solar wind by Ulysses from the previous solar minimum (1996-1997) to the more recent peculiar minimum (2008-2009). By changing only the magnetic field along the polar magnetic flux tube, consistent with solar and heliospheric observations at the two epochs, the model correctly predicts that the </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813412E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813412E">Solar system plasma Turbulence: Observations, inteRmittency and Multifractals</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Echim, Marius M. 2016-04-01 The FP7 project STORM is funded by the European Commission to "add value to existing data bases through a more comprehensive interpretation". STORM targets plasma and magnetic field databases collected in the solar wind (Ulysses and also some planetary missions), planetary magnetospheres (Venus Express, Cluster, a few orbits from Cassini), cometary magnetosheaths (e.g. Haley from Giotto observations). The project applies the same package of analysis methods on geomagnetic field observations from ground and on derived indices (e.g. AE, AL, AU, SYM-H). The analysis strategy adopted in STORM is built on the principle of increasing complexity, from lower (like, e.g., the Power Spectral Density - PSD) to higher order analyses (the Probability Distribution Functions - PDFs, Structure Functions - SFs, Fractals and Multifractals - MFs). Therefore STORM targets not only the spectral behavior of turbulent fluctuations but also their topology and scale behavior inferred from advanced mathematical algorithms and geometrical-like analogs. STORM started in January 2013 and ended in December 2015. We will report on a selection of scientific and technical achievements and will highlight: (1) the radial evolution of solar wind turbulence and intermittency based on Ulysses data with some contributions from Venus Express and Cluster; (2) comparative study of fast and slow wind turbulence and intermittency at solar minimum; (3) comparative study of the planetary response (Venus and Earth magnetosheaths) to turbulent solar wind; (4) the critical behavior of geomagnetic fluctuations and indices; (5) an integrated library for non-linear analysis of time series that includes all the approaches adopted in STORM to investigate solar system plasma turbulence. STORM delivers an unprecedented volume of analysed data for turbulence. The project made indeed a systematic survey, orbit by orbit, of data available from ESA repositories and Principal Investigators and provides results ordered as a </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730002050','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730002050">Model for energy transfer in the solar wind: Model results</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Barnes, A. A., Jr.; Hartle, R. E. 1972-01-01 A description is given of the results of solar wind flow in which the heating is due to (1) propagation and dissipation of hydromagnetic waves generated near the base of the wind, and (2) thermal conduction. A series of models is generated for fixed values of density, electron and proton temperature, and magnetic field at the base by varying the wave intensity at the base of the model. This series of models predicts the observed correlation between flow speed and proton temperature for a large range of velocities. The wave heating takes place in a shell about the sun greater than or approximately equal to 10 R thick. We conclude that large-scale variations observed in the solar wind are probably due mainly to variation in the hydromagnetic wave flux near the sun. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914676L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914676L">Data Assimilation in the Solar Wind: Challenges and First Results</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lang, Matthew; Browne, Phil; van Leeuwen, Peter Jan; Owens, Matt 2017-04-01 Data assimilation (DA) is currently underused in the solar wind field to improve the modelled variables using observations. Data assimilation has been used in Numerical Weather Prediction (NWP) models with great success, and it can be seen that the improvement of DA methods in NWP modelling has led to improvements in forecasting skill over the past 20-30 years. The state of the art DA methods developed for NWP modelling have never been applied to space weather models, hence it is important to implement the improvements that can be gained from these methods to improve our understanding of the solar wind and how to model it. The ENLIL solar wind model has been coupled to the EMPIRE data assimilation library in order to apply these advanced data assimilation methods to a space weather model. This coupling allows multiple data assimilation methods to be applied to ENLIL with relative ease. I shall discuss twin experiments that have been undertaken, applying the LETKF to the ENLIL model when a CME occurs in the observation and when it does not. These experiments show that there is potential in the application of advanced data assimilation methods to the solar wind field, however, there is still a long way to go until it can be applied effectively. I shall discuss these issues and suggest potential avenues for future research in this area. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760050074&hterms=Evolution+test&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DEvolution%2Btest','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760050074&hterms=Evolution+test&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DEvolution%2Btest">Solar wind stream evolution at large heliocentric distances - Experimental demonstration and the test of a model</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gosling, J. T.; Hundhausen, A. J.; Bame, S. J. 1976-01-01 A stream propagation model which neglects all dissipation effects except those occurring at shock interfaces, was used to compare Pioneer-10 solar wind speed observations, during the time when Pioneer 10, the earth, and the sun were coaligned, with near-earth Imp-7 observations of the solar wind structure, and with the theoretical predictions of the solar wind structure at Pioneer 10 derived from the Imp-7 measurements, using the model. The comparison provides a graphic illustration of the phenomenon of stream steepening in the solar wind with the attendant formation of forward-reverse shock pairs and the gradual decay of stream amplitudes with increasing heliocentric distance. The comparison also provides a qualitative test of the stream propagation model. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM13B2203T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM13B2203T">Statistical Methods for Quantifying the Variability of Solar Wind Transients of All Sizes</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tindale, E.; Chapman, S. C. 2016-12-01 The solar wind is inherently variable across a wide range of timescales, from small-scale turbulent fluctuations to the 11-year periodicity induced by the solar cycle. Each solar cycle is unique, and this change in overall cycle activity is coupled from the Sun to Earth via the solar wind, leading to long-term trends in space weather. Our work [Tindale & Chapman, 2016] applies novel statistical methods to solar wind transients of all sizes, to quantify the variability of the solar wind associated with the solar cycle. We use the same methods to link solar wind observations with those on the Sun and Earth. We use Wind data to construct quantile-quantile (QQ) plots comparing the statistical distributions of multiple commonly used solar wind-magnetosphere coupling parameters between the minima and maxima of solar cycles 23 and 24. We find that in each case the distribution is multicomponent, ranging from small fluctuations to extreme values, with the same functional form at all phases of the solar cycle. The change in PDF is captured by a simple change of variables, which is independent of the PDF model. Using this method we can quantify the quietness of the cycle 24 maximum, identify which variable drives the changing distribution of composite parameters such as ɛ, and we show that the distribution of ɛ is less sensitive to changes in its extreme values than that of its constituents. After demonstrating the QQ method on solar wind data, we extend the analysis to include solar and magnetospheric data spanning the same time period. We focus on GOES X-ray flux and WDC AE index data. Finally, having studied the statistics of transients across the full distribution, we apply the same method to time series of extreme bursts in each variable. Using these statistical tools, we aim to track the solar cycle-driven variability from the Sun through the solar wind and into the Earth's magnetosphere. Tindale, E. and S.C. Chapman (2016), Geophys. Res. Lett., 43(11), doi: 10 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22370297-study-density-modulation-index-inner-heliospheric-solar-wind-during-solar-cycle','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22370297-study-density-modulation-index-inner-heliospheric-solar-wind-during-solar-cycle">A study of density modulation index in the inner heliospheric solar wind during solar cycle 23</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Bisoi, Susanta Kumar; Janardhan, P.; Ingale, M. 2014-11-01 The ratio of the rms electron density fluctuations to the background density in the solar wind (density modulation index, ε {sub N} ≡ ΔN/N) is of vital importance for understanding several problems in heliospheric physics related to solar wind turbulence. In this paper, we have investigated the behavior of ε {sub N} in the inner heliosphere from 0.26 to 0.82 AU. The density fluctuations ΔN 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 Advancedmore » Composition Explorer. Our analysis reveals that 0.001 ≲ ε {sub N} ≲ 0.02 and does not vary appreciably with heliocentric distance. We also find that ε {sub 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 solar wind dynamic pressure over the recent peculiar solar minimum at the end of cycle 23.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1221389-depth-profiling-analysis-solar-wind-helium-collected-diamond-like-carbon-film-from-genesis','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1221389-depth-profiling-analysis-solar-wind-helium-collected-diamond-like-carbon-film-from-genesis">Depth profiling analysis of solar wind helium collected in diamond-like carbon film from Genesis</a> <a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a> Bajo, Ken-ichi; Olinger, Chad T.; Jurewicz, Amy J.G.; ... 2015-01-01 The distribution of solar-wind ions in Genesis mission collectors, as determined by depth profiling analysis, constrains the physics of ion solid interactions involving the solar wind. Thus, they provide an experimental basis for revealing ancient solar activities represented by solar-wind implants in natural samples. We measured the first depth profile of ⁴He in a collector; the shallow implantation (peaking at <20 nm) required us to use sputtered neutral mass spectrometry with post-photoionization by a strong field. The solar wind He fluence calculated using depth profiling is ~8.5 x 10¹⁴ cm⁻². The shape of the solar wind ⁴He depth profile ismore » consistent with TRIM simulations using the observed ⁴He velocity distribution during the Genesis mission. It is therefore likely that all solar-wind elements heavier than H are completely intact in this Genesis collector and, consequently, the solar particle energy distributions for each element can be calculated from their depth profiles. Ancient solar activities and space weathering of solar system objects could be quantitatively reproduced by solar particle implantation profiles.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021462&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021462&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bintensity%2Bmeasurement">Very long baseline IPS observations of the solar wind speed in the fast polar streams</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Rao, A. Pramesh; Ananthakrishnan, S.; Balasubramanian, V.; Coles, William A. 1995-01-01 Observations of intensity scintillation (IPS) with two or more spaced antennas have been widely used to measure the solar wind velocity. Such methods are particularly valuable in regions which spacecraft have not yet penetrated, but they are also very useful in improving the spatial temporal sampling of the solar wind, even in regions where spacecraft data are available. The principle of the measurement is to measure the time delay tau(sub d) between the scintillations observed with an antenna baseline b. The velocity estimate is just V = b/tau(sub d). The error in estimation of the time delay delta tau(sub d) is independent of the baseline length, thus the error in the velocity estimate delta V given by delta(V)/V approximately equals to (delta tau(sub d))/tau(sub d) is inversely proportional to tau(sub d) and hence to b. However the use of a long baseline b has a less obvious advantage; it provides a means for separating fast and slow contributions when both are present in the scattering region. Here we will present recent observations made using the large cylinder antenna at Ooty in the Nilgiri Hills of South India, and one of the 45 m dishes of GMRT near Pune in West-Central India. The baseline of 900 km is, by a considerable margin, the longest ever used for IPS and provides excellent velocity resolution. These results compared with the ULYSSES observations and other IPS measurements made closer to the sun with higher frequency instruments such as EISCAT and the VLBA will provide a precise measure of the velocity profile of the fast north-polar stream. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730002084','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730002084">The interaction of the solar wind with the interstellar medium</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Axford, W. I. 1972-01-01 The expected characteristics of the solar wind, extrapolated from the vicinity of the earth are described. Several models are examined for the interaction of the solar wind with the interstellar plasma and magnetic field. Various aspects of the penetration of neutral interstellar gas into the solar wind are considered. The dynamic effects of the neutral gas on the solar wind are described. Problems associated with the interaction of cosmic rays with the solar wind are discussed. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080031334&hterms=solar+energy+advantage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Benergy%2Badvantage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080031334&hterms=solar+energy+advantage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Benergy%2Badvantage">Recent Insights into the Nature of Turbulence in the Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Goldstein, Melvun L. 2008-01-01 During the past several years, studies of solar wind turbulence using data from Cluster and other spacecraft, and results from new numerical simulations, have revealed new aspects of solar wind turbulence. I will try to highlight some of that research. At the shortest length scales and highest frequencies, there is renewed interest in determining how the turbulence dissipates, e.g., whether by kinetic Alfven waves or whistler turbulence. Finding observational evidence for exponential damping of solar wind fluctuations has proven challenging. New studies using a combination of flux gate and search coil magnetometer data from Cluster have extended this search (in the spacecraft frame of reference) to more than 10 Hertz. New models and simulations are also being used to study the dissipation. A detailed study of fluctuations in the magnetosheath suggests that turbulent dissipation could be occurring at very thin current sheets as had been suggested by two-dimensional MHD simulations more than 20 years ago. Data from the four Cluster spacecraft, now at their maximum separation of 10,000 km provide new opportunities to investigate the symmetry properties, scale lengths, and the relative proportion of magnetic energy in parallel and perpendicular wave numbers of solar wind turbulence. By utilizing well-calibrated electron data, it has been possible to take advantage of the tetrahedral separation of Cluster in the solar wind near apogee to measure directly the compressibility and vorticity of the solar wind plasma. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P54D..01G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P54D..01G">(Over-)Reaction of the Cometary Plasma to Extreme Solar Wind Conditions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Goetz, C.; Tsurutani, B.; Henri, P.; Edberg, N. J. T.; Volwerk, M.; Nilsson, H.; Mokashi, P.; Heritier, K. L.; Behar, E.; Carr, C.; Eriksson, A.; Galand, M. F.; Odelstad, E.; Richter, I.; Rubin, M.; Simon Wedlund, C.; Wellbrock, A.; Glassmeier, K. H. 2017-12-01 The magnetometer onboard ESA's Rosetta orbiter detected its highest magnetic field magnitude of 250nT in July 2015, close to perihelion. This magnitude was an enhancement of a factor of five compared to normal values, which makes this the highest interplanetary magnetic field ever measured. We have examined the solar wind conditions at the time and found that a corotating interaction region (CIR), accompanied by a fast flow is the trigger for this unusual event. Because Rosetta does not have solar wind observations during the comet's active phase, we use ENLIL simulations as well as observations at Earth and Mars to constrain the solar wind parameters at the comet. Using a simple model for the magnetic field pile-up we can trace back the field in the coma to corresponding structures in the CIR. The large field is accompanied by a dramatic increase in electron and ion fluxes and energies. However, the electrons and ions in the field of view are not, as expected, increasing at the same time, instead the electrons follow the magnetic field, while the ion density increase is delayed. This is seen as evidence of the kinetic behaviour of the ions as opposed to a magnetized electron fluid. Combining the information on the plasma, we are able to identify at least three different regions in the plasma that have fundamentally different parameters. This allows us to separate the solar wind influence from the comet's effects on the plasma, a problem that is usually not solvable without a spacecraft monitoring the solar wind at the comet. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/971292','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/971292">The genesis solar-wind sample return mission</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Wiens, Roger C 2009-01-01 The compositions of the Earth's crust and mantle, and those of the Moon and Mars, are relatively well known both isotopically and elementally. The same is true of our knowledge of the asteroid belt composition, based on meteorite analyses. Remote measurements of Venus, the Jovian atmosphere, and the outer planet moons, have provided some estimates of their compositions. The Sun constitutes a large majority, > 99%, of all the matter in the solar system. The elemental composition of the photosphere, the visible 'surface' of the Sun, is constrained by absorption lines produced by particles above the surface. Abundances for manymore » elements are reported to the {+-}10 or 20% accuracy level. However, the abundances of other important elements, such as neon, cannot be determined in this way due to a relative lack of atomic states at low excitation energies. Additionally and most importantly, the isotopic composition of the Sun cannot be determined astronomically except for a few species which form molecules above sunspots, and estimates derived from these sources lack the accuracy desired for comparison with meteoritic and planetary surface samples measured on the Earth. The solar wind spreads a sample of solar particles throughout the heliosphere, though the sample is very rarified: collecting a nanogram of oxygen, the third most abundant element, in a square centimeter cross section at the Earth's distance from the Sun takes five years. Nevertheless, foil collectors exposed to the solar wind for periods of hours on the surface of the Moon during the Apollo missions were used to determine the helium and neon solar-wind compositions sufficiently to show that the Earth's atmospheric neon was significantly evolved relative to the Sun. Spacecraft instruments developed subsequently have provided many insights into the composition of the solar wind, mostly in terms of elemental composition. These instruments have the advantage of observing a number of parameters </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750044678&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dorbiting%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750044678&hterms=orbiting+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dorbiting%2Bwind">A search for solar wind velocity changes between 0.7 and 1 AU</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Intriligator, D. S.; Neugebauer, M. 1975-01-01 Observations are presented concerning the radial variations of the solar wind velocity between 0.7 and 1 AU in late 1968 and early 1969. The observations were made with instruments carried by Pioneer 9 and the earth-orbiting satellite OGO 5. The Pioneer and OGO velocity measurements are compared. It is found that the same basic solar wind velocity structure was seen at both spacecraft. No statistically significant dependence of average velocity on the radial distance from the sun could be observed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...836..108K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...836..108K">High-latitude Conic Current Sheets in the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Khabarova, Olga V.; Malova, Helmi V.; Kislov, Roman A.; Zelenyi, Lev M.; Obridko, Vladimir N.; Kharshiladze, Alexander F.; Tokumaru, Munetoshi; Sokół, Justyna M.; Grzedzielski, Stan; Fujiki, Ken'ichi 2017-02-01 We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2-3 au several times in 1994, as the CCS was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of conic-like magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk-Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.2768L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.2768L">MAVEN observations of the solar cycle 24 space weather conditions at Mars</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lee, C. O.; Hara, T.; Halekas, J. S.; Thiemann, E.; Chamberlin, P.; Eparvier, F.; Lillis, R. J.; Larson, D. E.; Dunn, P. A.; Espley, J. R.; Gruesbeck, J.; Curry, S. M.; Luhmann, J. G.; Jakosky, B. M. 2017-03-01 The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has been continuously observing the variability of solar soft X-rays and EUV irradiance, monitoring the upstream solar wind and interplanetary magnetic field conditions and measuring the fluxes of solar energetic ions and electrons since its arrival to Mars. In this paper, we provide a comprehensive overview of the space weather events observed during the first ˜1.9 years of the science mission, which includes the description of the solar and heliospheric sources of the space weather activity. To illustrate the variety of upstream conditions observed, we characterize a subset of the event periods by describing the Sun-to-Mars details using observations from the MAVEN solar Extreme Ultraviolet Monitor, solar energetic particle (SEP) instrument, Solar Wind Ion Analyzer, and Magnetometer together with solar observations using near-Earth assets and numerical solar wind simulation results from the Wang-Sheeley-Arge-Enlil model for some global context of the event periods. The subset of events includes an extensive period of intense SEP electron particle fluxes triggered by a series of solar flares and coronal mass ejection (CME) activity in December 2014, the impact by a succession of interplanetary CMEs and their associated SEPs in March 2015, and the passage of a strong corotating interaction region (CIR) and arrival of the CIR shock-accelerated energetic particles in June 2015. However, in the context of the weaker heliospheric conditions observed throughout solar cycle 24, these events were moderate in comparison to the stronger storms observed previously at Mars. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026711','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026711">Solar wind velocity and daily variation of cosmic rays</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ahluwalia, H. S.; Riker, J. F. 1985-01-01 Recently parameters applicable to the solar wind and the interplanetary magnetic field (IMF) have become much better defined. Superior quality of data bases that are now available, particularly for post-1971 period, make it possible to believe the long-term trends in the data. These data are correlated with the secular changes observed in the diurnal variation parameters obtained from neutron monitor data at Deep River and underground muon telescope data at Embudo (30 MEW) and Socorro (82 MWE). The annual mean amplitudes appear to have large values during the epochs of high speed solar wind streams. Results are discussed. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active">16</li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active">17</li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.1395S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.1395S">Solar wind alpha particle capture at Mars and Venus</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Stenberg, Gabriella; Barabash, Stas; Nilsson, Hans; Fedorov, A.; Brain, David; André, Mats Helium is detected in the atmospheres of both Mars and Venus. It is believed that radioactive decay of uranium and thorium in the interior of the planets' is not sufficient to account for the abundance of helium observed. Alpha particles in the solar wind are suggested to be an additional source of helium, especially at Mars. Recent hybrid simulations show that as much as 30We use ion data from the ASPERA-3 and ASPERA-4 instruments on Mars and Venus Express to estimate how efficient solar wind alpha particles are captured in the atmospheres of the two planets. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860040981&hterms=relationship+form&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drelationship%2Bform','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860040981&hterms=relationship+form&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drelationship%2Bform">Solar wind proton temperature-velocity relationship</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lopez, R. E.; Freeman, J. W. 1986-01-01 Helios 1 data are analyzed to find an experimental fit for the temperature-velocity relationship at 1 AU. It is shown that the proton temperature-velocity changes at a velocity of approximately 500 km/s. Interplanetary dynamic processes, i.e., stream interactions, are shown to affect the temperature-velocity relationships less than 22 percent; the functional form of these relationships appears to be preserved throughout the solar cycle. It is pointed out that any comprehensive model of the solar wind will have to address the difference in the temperature-velocity relationship between the low- and high-speed wind, since this is a product of the acceleration and subsequent heating process generating the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820042725&hterms=Wind+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DWind%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820042725&hterms=Wind+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DWind%2Benergy">Solar wind energy transfer through the magnetopause of an open magnetosphere</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lee, L. C.; Roederer, J. G. 1982-01-01 An expression is derived for the total power, transferred from the solar wind to an open magnetosphere, which consists of the electromagnetic energy rate and the particle kinetic energy rate. The total rate of energy transferred from the solar wind to an open magnetosphere mainly consists of kinetic energy, and the kinetic energy flux is carried by particles, penetrating from the solar wind into the magnetosphere, which may contribute to the observed flow in the plasma mantle and which will eventually be convected slowly toward the plasma sheet by the electric field as they flow down the tail. While the electromagnetic energy rate controls the near-earth magnetospheric activity, the kinetic energy rate should dominate the dynamics of the distant magnetotail. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27694887','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27694887">Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Lugaz, Noé; Farrugia, Charles J; Huang, Chia-Lin; Winslow, Reka M; Spence, Harlan E; Schwadron, Nathan A 2016-10-03 The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000-100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values <1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM53D2260G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM53D2260G">An empirical model to forecast solar wind velocity through statistical modeling</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gao, Y.; Ridley, A. J. 2013-12-01 The accurate prediction of the solar wind velocity has been a major challenge in the space weather community. Previous studies proposed many empirical and semi-empirical models to forecast the solar wind velocity based on either the historical observations, e.g. the persistence model, or the instantaneous observations of the sun, e.g. the Wang-Sheeley-Arge model. In this study, we use the one-minute WIND data from January 1995 to August 2012 to investigate and compare the performances of 4 models often used in literature, here referred to as the null model, the persistence model, the one-solar-rotation-ago model, and the Wang-Sheeley-Arge model. It is found that, measured by root mean square error, the persistence model gives the most accurate predictions within two days. Beyond two days, the Wang-Sheeley-Arge model serves as the best model, though it only slightly outperforms the null model and the one-solar-rotation-ago model. Finally, we apply the least-square regression to linearly combine the null model, the persistence model, and the one-solar-rotation-ago model to propose a 'general persistence model'. By comparing its performance against the 4 aforementioned models, it is found that the accuracy of the general persistence model outperforms the other 4 models within five days. Due to its great simplicity and superb performance, we believe that the general persistence model can serve as a benchmark in the forecast of solar wind velocity and has the potential to be modified to arrive at better models. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990028110&hterms=Whole+Sale&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWhole%2BSale','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990028110&hterms=Whole+Sale&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWhole%2BSale">A search for the coronal origins of fast solar wind streams during the whole sun month period</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lazarus, A. J.; Steinberg, J. T.; Biesecker, D. A.; Forsyth, R. J.; Galvin, A. B.; Ipavich, F. M.; Gibson, S. E.; Lecinski, A.; Hassler, D. M.; Hoeksema, J. T.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_19990028110'); toggleEditAbsImage('author_19990028110_show'); toggleEditAbsImage('author_19990028110_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_19990028110_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_19990028110_hide"> 1997-01-01 The solar wind streams observed from the Solar and Heliospheric Observatory (SOHO) and Ulysses, WIND spacecraft during the whole solar month are discussed. These solar wind streams, with speeds in excess of 500 km/s, were detected from 10 August to 8 September 1996. The data covering Carrington rotations 1912 and 1913 are presented. The magnetic field azimuthal angle observations at 1 AU from WIND show that all the streams are associated with outward fields near the sun. The stream structure near 320 deg was associated with the central meridian passage of a coronal hole. The Fe XIV ground based observations show a region of low intensity in the zero to 170 deg longitude. The question of whether the streams arise from equatorial features or represent flows coming from higher latitude features is not solved. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667169-modeling-solar-wind-ulysses-voyager-new-horizons-spacecraft','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667169-modeling-solar-wind-ulysses-voyager-new-horizons-spacecraft">MODELING THE SOLAR WIND AT THE ULYSSES , VOYAGER , AND NEW HORIZONS SPACECRAFT</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kim, T. K.; Pogorelov, N. V.; Zank, G. P. The outer heliosphere is a dynamic region shaped largely by the interaction between the solar wind and the interstellar medium. While interplanetary magnetic field and plasma observations by the Voyager spacecraft have significantly improved our understanding of this vast region, modeling the outer heliosphere still remains a challenge. We simulate the three-dimensional, time-dependent solar wind flow from 1 to 80 astronomical units (au), where the solar wind is assumed to be supersonic, using a two-fluid model in which protons and interstellar neutral hydrogen atoms are treated as separate fluids. We use 1 day averages of the solar wind parameters frommore » the OMNI data set as inner boundary conditions to reproduce time-dependent effects in a simplified manner which involves interpolation in both space and time. Our model generally agrees with Ulysses data in the inner heliosphere and Voyager data in the outer heliosphere. Ultimately, we present the model solar wind parameters extracted along the trajectory of the New Horizons spacecraft. We compare our results with in situ plasma data taken between 11 and 33 au and at the closest approach to Pluto on 2015 July 14.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930049627&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dbackground%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930049627&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dbackground%2Bwind">Ions with low charges in the solar wind as measured by SWICS on board Ulysses. [Solar Wind Ion Composition Spectrometer</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Geiss, J.; Ogilvie, K. W.; Von Steiger, R.; Mall, U.; Gloeckler, G.; Galvin, A. B.; Ipavich, F.; Wilken, B.; Gliem, F. 1992-01-01 We present new data on rare ions in the solar wind. Using the Ulysses-SWICS instrument with its very low background we have searched for low-charge ions during a 6-d period of low-speed solar wind and established sensitive upper limits for many species. In the solar wind, we found He(1+)/He(2+) of less than 5 x 10 exp -4. This result and the charge state distributions of heavier elements indicate that all components of the investigated ion population went through a regular coronal expansion and experienced the typical electron temperatures of 1 to 2 million Kelvin. We argue that the virtual absence of low-charge ions demonstrates a very low level of nonsolar contamination in the source region of the solar wind sample we studied. Since this sample showed the FlP effect typical for low-speed solar wind, i.e., an enhancement in the abundances of elements with low first ionization potential, we conclude that this enhancement was caused by an ion-atom separation mechanism operating near the solar surface and not by foreign material in the corona. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913260S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913260S">On the properties of energy transfer in solar wind turbulence.</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sorriso-Valvo, Luca; Marino, Raffaele; Chen, Christopher H. K.; Wicks, Robert; Nigro, Giuseppina 2017-04-01 Spacecraft observations have shown that the solar wind plasma is heated during its expansion in the heliosphere. The necessary energy is made available at small scales by a turbulent cascade, although the nature of the heating processes is still debated. Because of the intermittent nature of turbulence, the small-scale energy is inhomogeneously distributed in space, resulting for example in the formation of highly localized current sheets and eddies. In order to understand the small-scale plasma processes occurring in the solar wind, the global and local properties of such energy distribution must be known. Here we study such properties using a proxy derived from the Von Karman-Howart relation for magnetohydrodynamics. The statistical properties of the energy transfer rate in the fluid range of scales are studied in detail using WIND spacecraft plasma and magnetic field measurements and discussed in the framework of the multifractal turbulent cascade. Dependence of the energy dissipation proxy on the solar wind conditions (speed, type, solar activity...) is analysed, and its evolution during solar wind expansion in the heliosphere is described using Helios II and Ulysses measurements. A comparison with other proxies, such as the PVI, is performed. Finally, the local singularity properties of the energy dissipation proxy are conditionally compared to the corresponding particle velocity distributions. This allows the identification of specific plasma features occurring near turbulent dissipation events, and could be used as enhanced mode trigger in future space missions. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22356728-turbulence-driven-coronal-heating-improvements-empirical-forecasting-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22356728-turbulence-driven-coronal-heating-improvements-empirical-forecasting-solar-wind">Turbulence-driven coronal heating and improvements to empirical forecasting of the solar wind</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Woolsey, Lauren N.; Cranmer, Steven R. Forecasting models of the solar wind often rely on simple parameterizations of the magnetic field that ignore the effects of the full magnetic field geometry. In this paper, we present the results of two solar wind prediction models that consider the full magnetic field profile and include the effects of Alfvén waves on coronal heating and wind acceleration. The one-dimensional magnetohydrodynamic code ZEPHYR self-consistently finds solar wind solutions without the need for empirical heating functions. Another one-dimensional code, introduced in this paper (The Efficient Modified-Parker-Equation-Solving Tool, TEMPEST), can act as a smaller, stand-alone code for use in forecasting pipelines. TEMPESTmore » is written in Python and will become a publicly available library of functions that is easy to adapt and expand. We discuss important relations between the magnetic field profile and properties of the solar wind that can be used to independently validate prediction models. ZEPHYR provides the foundation and calibration for TEMPEST, and ultimately we will use these models to predict observations and explain space weather created by the bulk solar wind. We are able to reproduce with both models the general anticorrelation seen in comparisons of observed wind speed at 1 AU and the flux tube expansion factor. There is significantly less spread than comparing the results of the two models than between ZEPHYR and a traditional flux tube expansion relation. We suggest that the new code, TEMPEST, will become a valuable tool in the forecasting of space weather.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...787..160W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...787..160W">Turbulence-driven Coronal Heating and Improvements to Empirical Forecasting of the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Woolsey, Lauren N.; Cranmer, Steven R. 2014-06-01 Forecasting models of the solar wind often rely on simple parameterizations of the magnetic field that ignore the effects of the full magnetic field geometry. In this paper, we present the results of two solar wind prediction models that consider the full magnetic field profile and include the effects of Alfvén waves on coronal heating and wind acceleration. The one-dimensional magnetohydrodynamic code ZEPHYR self-consistently finds solar wind solutions without the need for empirical heating functions. Another one-dimensional code, introduced in this paper (The Efficient Modified-Parker-Equation-Solving Tool, TEMPEST), can act as a smaller, stand-alone code for use in forecasting pipelines. TEMPEST is written in Python and will become a publicly available library of functions that is easy to adapt and expand. We discuss important relations between the magnetic field profile and properties of the solar wind that can be used to independently validate prediction models. ZEPHYR provides the foundation and calibration for TEMPEST, and ultimately we will use these models to predict observations and explain space weather created by the bulk solar wind. We are able to reproduce with both models the general anticorrelation seen in comparisons of observed wind speed at 1 AU and the flux tube expansion factor. There is significantly less spread than comparing the results of the two models than between ZEPHYR and a traditional flux tube expansion relation. We suggest that the new code, TEMPEST, will become a valuable tool in the forecasting of space weather. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850016253&hterms=simple+linear+regression+analysis&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsimple%2Blinear%2Bregression%2Banalysis','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850016253&hterms=simple+linear+regression+analysis&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsimple%2Blinear%2Bregression%2Banalysis">The application of dimensional analysis to the problem of solar wind-magnetosphere energy coupling</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bargatze, L. F.; Mcpherron, R. L.; Baker, D. N.; Hones, E. W., Jr. 1984-01-01 The constraints imposed by dimensional analysis are used to find how the solar wind-magnetosphere energy transfer rate depends upon interplanetary parameters. The analyses assume that only magnetohydrodynamic processes are important in controlling the rate of energy transfer. The study utilizes ISEE-3 solar wind observations, the AE index, and UT from three 10-day intervals during the International Magnetospheric Study. Simple linear regression and histogram techniques are used to find the value of the magnetohydrodynamic coupling exponent, alpha, which is consistent with observations of magnetospheric response. Once alpha is estimated, the form of the solar wind energy transfer rate is obtained by substitution into an equation of the interplanetary variables whose exponents depend upon alpha. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080038681','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080038681">Observation of Solar Wind Charge Exchange Emission from Exospheric Material in and Outside Earth's Magnetosheath</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Snowden, S. L.; Collier, M. R.; Cravens, T.; Kuntz, K. D.; Lepri, S. T.; Robertson, I.; Tomas, L. 2008-01-01 A long XMM-Newton exposure is used to observe solar wind charge exchange (SWCX) emission from exospheric material in and outside Earth s magnetosheath. The light curve of the O VII (0.5-0.62 keV) band is compared with a model for the expected emission, and while the emission is faint and the light curve has considerable scatter, the correlation is significant to better than 99.9%. This result demonstrates the validity of the geocoronal SWCX emission model for predicting a contribution to astrophysical observations to a scale factor of order unity (1.36). The results also demonstrate the potential utility of using X-ray observations to study global phenomena of the magnetosheath which currently are only investigated using in situ measurements. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRA..116.3229N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRA..116.3229N">Solar wind driving and substorm triggering</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Newell, Patrick T.; Liou, Kan 2011-03-01 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 dΦMP/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 σ = 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 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JASTP.102..185O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JASTP.102..185O">The dispersion analysis of drift velocity in the study of solar wind flows</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Olyak, Maryna 2013-09-01 In this work I consider a method for the study of the solar wind flows at distances from the Sun more than 1 AU. The method is based on the analysis of drift velocity dispersion that was obtained from the simultaneous scintillation observations in two antennas. I considered dispersion dependences for different models of the solar wind, and I defined its specificity for each model. I have determined that the presence of several solar wind flows significantly affects the shape and the slope of the dispersion curve. The maximum slope angle is during the passage of the fast solar wind flow near the Earth. If a slow flow passes near the Earth, the slope of the dispersion curve decreases. This allows a more precise definition of the velocity and flow width compared to the traditional scintillation method. Using the comparison of experimental and theoretical dispersion curves, I calculated the velocity and width of solar wind flows and revealed the presence of significant velocity fluctuations which accounted for about 60% of the average velocity. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH53A2547G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH53A2547G">Comparing Temporally-Separated Solar Wind Structures at 1 AU (STEREO A and OMNI)</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Galvin, A. B.; Farrugia, C. J.; Jian, L. K. 2017-12-01 One may use the longitudinal coverage of different spacecraft assets, or the same asset over sequential Carrington Rotations, to study the solar wind behavior from long-lived structures (coronal holes, active regions), or occasionally observe the extent of transient structures (Farrugia et al., 2011). This is of interest as the evolution of the extent and persistence of interplanetary coronal mass ejections (ICMEs) and of stream interaction regions (SIRs) have implications for space weather forecasting. One challenge is that one must be aware of the temporal evolution of the structure on the Sun and the affect of `sampling' different solar sources due to different solar latitudes of the in-situ spacecraft observations. Here we look at case studies of recent event time intervals during 2015-2017 where solar wind emanating from long-lived coronal-hole structures are observed both at STEREO A and at near-Earth assets (OMNI2). The observations are taken at similar solar latitudes and longitudes but temporally separated by several days or weeks. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770032937&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770032937&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dwind%2Bmonitor">Solar wind and extreme ultraviolet modulation of the lunar ionosphere/exosphere</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Freeman, J. W. 1976-01-01 The ALSEP/SIDE detectors routinely monitor the dayside lunar ionosphere. Variations in the ionosphere are found to correlate with both the 2800 MHz radio index which can be related to solar EUV and with the solar wind proton flux. For the solar wind, the ionospheric variation is proportionately greater than that of the solar wind. This suggests an amplification effect on the lunar atmosphere due perhaps to sputtering of the surface or, less probably, an inordinate enhancement of noble gases in the solar wind. The surface neutral number density is calculated under the assumption of neon gas. During a quiet solar wind this number agrees with or is slightly above that expected for neon accreted from the solar wind. During an enhanced solar wind the neutral number density is much higher. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20120015694&hterms=protons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dprotons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20120015694&hterms=protons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dprotons">Three-Dimensional Magnetohydrodynamic Modeling of the Solar Wind Including Pickup Protons and Turbulence Transport</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Usmanov, Arcadi V.; Goldstein, Melvyn L.; Matthaeus, William H. 2012-01-01 To study the effects of interstellar pickup protons and turbulence on the structure and dynamics of the solar wind, we have developed a fully three-dimensional magnetohydrodynamic solar wind model that treats interstellar pickup protons as a separate fluid and incorporates the transport of turbulence and turbulent heating. The governing system of equations combines the mean-field equations for the solar wind plasma, magnetic field, and pickup protons and the turbulence transport equations for the turbulent energy, normalized cross-helicity, and correlation length. The model equations account for photoionization of interstellar hydrogen atoms and their charge exchange with solar wind protons, energy transfer from pickup protons to solar wind protons, and plasma heating by turbulent dissipation. Separate mass and energy equations are used for the solar wind and pickup protons, though a single momentum equation is employed under the assumption that the pickup protons are comoving with the solar wind protons.We compute the global structure of the solar wind plasma, magnetic field, and turbulence in the region from 0.3 to 100 AU for a source magnetic dipole on the Sun tilted by 0 deg - .90 deg and compare our results with Voyager 2 observations. The results computed with and without pickup protons are superposed to evaluate quantitatively the deceleration and heating effects of pickup protons, the overall compression of the magnetic field in the outer heliosphere caused by deceleration, and the weakening of corotating interaction regions by the thermal pressure of pickup protons. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22525705-evidence-newly-initiated-reconnection-solar-wind-au','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22525705-evidence-newly-initiated-reconnection-solar-wind-au">EVIDENCE FOR NEWLY INITIATED RECONNECTION IN THE SOLAR WIND AT 1 AU</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Xu, Xiaojun; Ma, Yonghui; Wong, Hon-Cheng 2015-08-10 We report the first evidence for a large-scale reconnection exhaust newly initiated in the solar wind using observations from three spacecraft: ACE, Wind, and ARTEMIS P2. We identified a well-structured X-line exhaust using measurements from ARTEMIS P2 in the downstream solar wind. However, in the upstream solar wind, ACE detected the same current sheet that corresponds to the exhaust identified by ARTEMIS P2 data without showing any reconnection signals. We cannot find any reconnection signals from Wind located between ACE and ARTEMIS P2. Within the exhaust, a magnetic island is identified, which is not consistent with the quasi-steady feature asmore » previously reported and provides further evidence that the reconnection is newly initiated. Our observations show that the entering of energetic particles, probably from Earth's bow shock, makes the crucial difference between the non-reconnecting current sheet and the exhaust. Since no obvious driving factors are responsible for the reconnection initiation, we infer that these energetic particles probably play an important role in the reconnection initiation. Theoretical analysis also shows support for this potential mechanism.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750002821','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750002821">Termination of the solar wind in the hot, partially ionized interstellar medium. Ph.D. Thesis</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lombard, C. K. 1974-01-01 Theoretical foundations for understanding the problem of the termination of the solar wind are reexamined in the light of most recent findings concerning the states of the solar wind and the local interstellar medium. The investigation suggests that a simple extention of Parker's (1961) analytical model provides a useful approximate description of the combined solar wind, interstellar wind plasma flowfield under conditions presently thought to occur. A linear perturbation solution exhibiting both the effects of photoionization and charge exchange is obtained for the supersonic solar wind. A numerical algorithm is described for computing moments of the non-equilibrium hydrogen distribution function and associated source terms for the MHD equations. Computed using the algorithm in conjunction with the extended Parker solution to approximate the plasma flowfield, profiles of hydrogen number density are given in the solar wind along the upstream and downstream axes of flow with respect to the direction of the interstellar wind. Predictions of solar Lyman-alpha backscatter intensities to be observed at 1 a.u. have been computed, in turn, from a set of such hydrogen number density profiles varied over assumed conditions of the interstellar wind. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active">17</li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active">18</li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...853...85V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...853...85V">3D Anisotropy of Solar Wind Turbulence, Tubes, or Ribbons?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Verdini, Andrea; Grappin, Roland; Alexandrova, Olga; Lion, Sonny 2018-01-01 We study the anisotropy with respect to the local magnetic field of turbulent magnetic fluctuations at magnetofluid scales in the solar wind. Previous measurements in the fast solar wind obtained axisymmetric anisotropy, despite that the analysis method allows nonaxisymmetric structures. These results are probably contaminated by the wind expansion that introduces another symmetry axis, namely, the radial direction, as indicated by recent numerical simulations. These simulations also show that while the expansion is strong, the principal fluctuations are in the plane perpendicular to the radial direction. Using this property, we separate 11 yr of Wind spacecraft data into two subsets characterized by strong and weak expansion and determine the corresponding turbulence anisotropy. Under strong expansion, the small-scale anisotropy is consistent with the Goldreich & Sridhar critical balance. As in previous works, when the radial symmetry axis is not eliminated, the turbulent structures are field-aligned tubes. Under weak expansion, we find 3D anisotropy predicted by the Boldyrev model, that is, turbulent structures are ribbons and not tubes. However, the very basis of the Boldyrev phenomenology, namely, a cross-helicity increasing at small scales, is not observed in the solar wind: the origin of the ribbon formation is unknown. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003238&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbackground%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003238&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbackground%2Bwind">Fading Coronal Structure and the Onset of Turbulence in the Young Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> DeForest, C. E.; Matthaeus, W. H.; Viall, N. M.; Cranmer, S. R. 2016-01-01 Above the top of the solar corona, the young, slow solar wind transitions from low-beta, magnetically structured flow dominated by radial structures to high-beta, less structured flow dominated by hydrodynamics. This transition, long inferred via theory, is readily apparent in the sky region close to 10deg from the Sun in processed, background-subtracted solar wind images. We present image sequences collected by the inner Heliospheric Imager instrument on board the Solar-Terrestrial Relations Observatory (STEREO/HI1) in 2008 December, covering apparent distances from approximately 4deg to 24deg from the center of the Sun and spanning this transition in the large-scale morphology of the wind. We describe the observation and novel techniques to extract evolving image structure from the images, and we use those data and techniques to present and quantify the clear textural shift in the apparent structure of the corona and solar wind in this altitude range. We demonstrate that the change in apparent texture is due both to anomalous fading of the radial striae that characterize the corona and to anomalous relative brightening of locally dense puffs of solar wind that we term "flocculae." We show that these phenomena are inconsistent with smooth radial flow, but consistent with the onset of hydrodynamic or magnetohydrodynamic instabilities leading to a turbulent cascade in the young solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667456-fading-coronal-structure-onset-turbulence-young-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667456-fading-coronal-structure-onset-turbulence-young-solar-wind">FADING CORONAL STRUCTURE AND THE ONSET OF TURBULENCE IN THE YOUNG SOLAR WIND</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> DeForest, C. E.; Matthaeus, W. H.; Viall, N. M. Above the top of the solar corona, the young, slow solar wind transitions from low- β , magnetically structured flow dominated by radial structures to high- β , less structured flow dominated by hydrodynamics. This transition, long inferred via theory, is readily apparent in the sky region close to 10° from the Sun in processed, background-subtracted solar wind images. We present image sequences collected by the inner Heliospheric Imager instrument on board the Solar-Terrestrial Relations Observatory ( STEREO /HI1) in 2008 December, covering apparent distances from approximately 4° to 24° from the center of the Sun and spanning this transitionmore » in the large-scale morphology of the wind. We describe the observation and novel techniques to extract evolving image structure from the images, and we use those data and techniques to present and quantify the clear textural shift in the apparent structure of the corona and solar wind in this altitude range. We demonstrate that the change in apparent texture is due both to anomalous fading of the radial striae that characterize the corona and to anomalous relative brightening of locally dense puffs of solar wind that we term “flocculae.” We show that these phenomena are inconsistent with smooth radial flow, but consistent with the onset of hydrodynamic or magnetohydrodynamic instabilities leading to a turbulent cascade in the young solar wind.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6582266-interplanetary-scintillation-large-elongation-angles-response-solar-wind-density-structure','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6582266-interplanetary-scintillation-large-elongation-angles-response-solar-wind-density-structure">Interplanetary scintillation at large elongation angles: Response to solar wind density structure</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Erskine, F.T.; Cronyn, W.M.; Shawhan, S.D. 1978-09-01 Synoptic interplanetary scintillation (IPS) index measurements were taken at 34.3 MHz during May-December 1974 using the University of Iowa Coca Cross radiotelescope on a 'grid' of 150 selected radio sources covering solar elongation angles up to 180/sup 0/. Over 80 of these sources displayed definite IPS. The solar elongation dependence of the 34.3-MHz IPS index is consistent with the elongation angle dependence measured at higher frequencies. Large enhancements (factors of> or approx. =2) of the IPS index are found to coincide with the solar wind (proton density increases greater than 10 cm/sup -3/ as measured by Imp 7 and 8more » for nearly all observed IPS sources throughout the sky. These 'all-sky' IPS enhancements appear to be caused by incresed contributions to the scintillation power by turbulent plasma in regions close to the earth (< or approx. =0.3AU) in all directions. Correlation analysis confirms the IPS response to solar wind density and indicates that the events are due primarily to the corotating solar wind turbulent plasma structures which dominated the interplanetary medium during 1974. The expected IPS space-time signature for a simple model of an approaching corotating turbulent structure is not apparent in our observations. In some cases, the enhancement variatons can be attributed to structural differences in the solar wind density turbulence in and out of the ecliptic.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5063966','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5063966">Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Lugaz, Noé; Farrugia, Charles J.; Huang, Chia-Lin; Winslow, Reka M.; Spence, Harlan E.; Schwadron, Nathan A. 2016-01-01 The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000–100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values <1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets. PMID:27694887 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...829...88L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...829...88L">Plasma-field Coupling at Small Length Scales in Solar Wind Near 1 AU</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Livadiotis, G.; Desai, M. I. 2016-10-01 In collisionless plasmas such as the solar wind, the coupling between plasma constituents and the embedded magnetic field occurs on various temporal and spatial scales, and is primarily responsible for the transfer of energy between waves and particles. Recently, it was shown that the transfer of energy between solar wind plasma particles and waves is governed by a new and unique relationship: the ratio between the magnetosonic energy and the plasma frequency is constant, E ms/ω pl ˜ ℏ*. This paper examines the variability and substantial departure of this ratio from ℏ* observed at ˜1 au, which is caused by a dispersion of fast magnetosonic (FMS) waves. In contrast to the efficiently transferred energy in the fast solar wind, the lower efficiency of the slow solar wind can be caused by this dispersion, whose relation and characteristics are derived and studied. In summary, we show that (I) the ratio E ms/ω pl transitions continuously from the slow to the fast solar wind, tending toward the constant ℏ* (II) the transition is more efficient for larger thermal, Alfvén, or FMS speeds; (III) the fast solar wind is almost dispersionless, characterized by quasi-constant values of the FMS speed, while the slow wind is subject to dispersion that is less effective for larger wind or magnetosonic speeds; and (IV) the constant ℏ* is estimated with the best known precision, ℏ* ≈ (1.160 ± 0.083) × 10-22 Js. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663803-high-latitude-conic-current-sheets-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663803-high-latitude-conic-current-sheets-solar-wind">High-latitude Conic Current Sheets in the Solar Wind</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Khabarova, Olga V.; Obridko, Vladimir N.; Kharshiladze, Alexander F. We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2–3 au several times in 1994, as the CCSmore » was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of conic-like magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/ nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk–Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA23A2545M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA23A2545M">Solar Wind drivers affecting GIC magnitude in New Zealand.</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mac Manus, D. H.; Rodger, C. J.; Dalzell, M.; Petersen, T.; Clilverd, M. A. 2017-12-01 Interplanetary shocks arriving at the Earth drive magnetosphere and ionosphere current systems. Ground based magnetometers detect the time derivation of the horizontal magnetic field (dBH/dt) which can indicate the strength of these ionospheric currents. The strong dBH/dt spikes have been observed to cause large Geomagnetically Induced Currents (GIC) in New Zealand. Such could, potentially lead to large scale damage to technological infrastructure such as power network transformers; one transformer was written off in New Zealand after a sudden commencement on 6 November 2001. The strength of the incoming interplanetary shocks are monitored by satellite measurements undertaken at the L1 point. Such measurements could give power network operators a 20-60 minute warning before potentially damaging GIC occurs. In this presentation we examine solar wind measurements from the Advanced Composition Explorer (ACE), Wind, and the Solar and Heliospheric Observatory (SOHO). We contrast those solar wind observations with GIC measured in New Zealand's South Island from 2001 to 2016. We are searching for a consistent relationship between the incoming interplanetary shock and the GIC magnitude. Such a relationship would allow Transpower New Zealand Limited a small time window to implement mitigation plans in order to restrict any GIC-caused damage. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JASTP.171...94P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JASTP.171...94P">Tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Prikryl, Paul; Bruntz, Robert; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel 2018-06-01 Occurrence of severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system is investigated. It is observed that significant snowfall, wind and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur within a few days after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., 2009, 2016) is corroborated for the southern hemisphere. Cases of severe weather events are examined in the context of the magnetosphere-ionosphere-atmosphere (MIA) coupling. Physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., 1990) reveal that propagating waves originating in the lower thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere and initiate convection to form cloud/precipitation bands. It is primarily the energy provided by release of latent heat that leads to intensification of storms. These results indicate that vertical coupling in the atmosphere exerts downward control from solar wind to the lower atmospheric levels influencing tropospheric weather development. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...823..145F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...823..145F">An Investigation of the Sources of Earth-directed Solar Wind during Carrington Rotation 2053</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Fazakerley, A. N.; Harra, L. K.; van Driel-Gesztelyi, L. 2016-06-01 In this work we analyze multiple sources of solar wind through a full Carrington Rotation (CR 2053) by analyzing the solar data through spectroscopic observations of the plasma upflow regions and the in situ data of the wind itself. Following earlier authors, we link solar and in situ observations by a combination of ballistic backmapping and potential-field source-surface modeling. We find three sources of fast solar wind that are low-latitude coronal holes. The coronal holes do not produce a steady fast wind, but rather a wind with rapid fluctuations. The coronal spectroscopic data from Hinode’s Extreme Ultraviolet Imaging Spectrometer show a mixture of upflow and downflow regions highlighting the complexity of the coronal hole, with the upflows being dominant. There is a mix of open and multi-scale closed magnetic fields in this region whose (interchange) reconnections are consistent with the up- and downflows they generate being viewed through an optically thin corona, and with the strahl directions and freeze-in temperatures found in in situ data. At the boundary of slow and fast wind streams there are three short periods of enhanced-velocity solar wind, which we term intermediate based on their in situ characteristics. These are related to active regions that are located beside coronal holes. The active regions have different magnetic configurations, from bipolar through tripolar to quadrupolar, and we discuss the mechanisms to produce this intermediate wind, and the important role that the open field of coronal holes adjacent to closed-field active regions plays in the process. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002412','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002412">Genesis Solar Wind Science Canister Components Curated as Potential Solar Wind Collectors and Reference Contamination Sources</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Allton, J. H.; Gonzalez, C. P.; Allums, K. K. 2016-01-01 The Genesis mission collected solar wind for 27 months at Earth-Sun L1 on both passive and active collectors carried inside of a Science Canister, which was cleaned and assembled in an ISO Class 4 cleanroom prior to launch. The primary passive collectors, 271 individual hexagons and 30 half-hexagons of semiconductor materials, are described in. Since the hard landing reduced the 301 passive collectors to many thousand smaller fragments, characterization and posting in the online catalog remains a work in progress, with about 19% of the total area characterized to date. Other passive collectors, surfaces of opportunity, have been added to the online catalog. For species needing to be concentrated for precise measurement (e.g. oxygen and nitrogen isotopes) an energy-independent parabolic ion mirror focused ions onto a 6.2 cm diameter target. The target materials, as recovered after landing, are described in. The online catalog of these solar wind collectors, a work in progress, can be found at: http://curator.jsc.nasa.gov/gencatalog/index.cfm This paper describes the next step, the cataloging of pieces of the Science Canister, which were surfaces exposed to the solar wind or component materials adjacent to solar wind collectors which may have contributed contamination. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040200985&hterms=HTML&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DHTML','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040200985&hterms=HTML&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DHTML">Wind and IMP 8 Solar Wind, Magnetosheath and Shock Data</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 2004-01-01 The purpose of this project was to provide the community access to magnetosheath data near Earth. We provided 27 years of IMP 8 magnetosheath proton velocities, densities, and temperatures with our best (usually 1-min.) time resolution. IMP 8 crosses the magnetosheath twice each 125 day orbit, and we provided magnetosheath data for the roughly 27 years of data for which magnetometer data are also available (which are needed to reliably pick boundaries). We provided this 27 years of IMP 8 magnetosheath data to the NSSDC; this data is now integrated with the IMP 8 solar wind data with flags indicating whether each data point is in the solar wind, magnetosheath, or at the boundary between the two regions. The plasma speed, density, and temperature are provided for each magnetosheath point. These data are also available on the MIT web site ftp://space .mit.edu/pub/plasma/imp/www/imp.html. We provide ASCII time-ordered rows of data giving the observation time, the spacecraft position in GSE, the velocity is GSE, the density and temperature for protons. We also have analyzed and archived on our web site the Wind magnetosheath plasma parameters. These consist of ascii files of the proton and alpha densities, speeds, and thermal speeds. These data are available at ftp://space.mit.edu/pub/plasma/wind/sheath These are the two products promised in the work statement and they have been completed in full. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Icar..300...47R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Icar..300...47R">Solar Energetic Particles (SEP) and Galactic Cosmic Rays (GCR) as tracers of solar wind conditions near Saturn: Event lists and applications</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Roussos, E.; Jackman, C. M.; Thomsen, M. F.; Kurth, W. S.; Badman, S. V.; Paranicas, C.; Kollmann, P.; Krupp, N.; Bučík, R.; Mitchell, D. G.; Krimigis, S. M.; Hamilton, D. C.; Radioti, A. 2018-01-01 The lack of an upstream solar wind monitor poses a major challenge to any study that investigates the influence of the solar wind on the configuration and the dynamics of Saturn's magnetosphere. Here we show how Cassini MIMI/LEMMS observations of Solar Energetic Particle (SEP) and Galactic Cosmic Ray (GCR) transients, that are both linked to energetic processes in the heliosphere such us Interplanetary Coronal Mass Ejections (ICMEs) and Corotating Interaction Regions (CIRs), can be used to trace enhanced solar wind conditions at Saturn's distance. SEP protons can be easily distinguished from magnetospheric ions, particularly at the MeV energy range. Many SEPs are also accompanied by strong GCR Forbush Decreases. GCRs are detectable as a low count-rate noise signal in a large number of LEMMS channels. As SEPs and GCRs can easily penetrate into the outer and middle magnetosphere, they can be monitored continuously, even when Cassini is not situated in the solar wind. A survey of the MIMI/LEMMS dataset between 2004 and 2016 resulted in the identification of 46 SEP events. Most events last more than two weeks and have their lowest occurrence rate around the extended solar minimum between 2008 and 2010, suggesting that they are associated to ICMEs rather than CIRs, which are the main source of activity during the declining phase and the minimum of the solar cycle. We also list of 17 time periods ( > 50 days each) where GCRs show a clear solar periodicity ( ∼ 13 or 26 days). The 13-day period that derives from two CIRs per solar rotation dominates over the 26-day period in only one of the 17 cases catalogued. This interval belongs to the second half of 2008 when expansions of Saturn's electron radiation belts were previously reported to show a similar periodicity. That observation not only links the variability of Saturn's electron belts to solar wind processes, but also indicates that the source of the observed periodicity in GCRs may be local. In this case GCR </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4394680','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4394680">The role of turbulence in coronal heating and solar wind expansion</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Cranmer, Steven R.; Asgari-Targhi, Mahboubeh; Miralles, Mari Paz; Raymond, John C.; Strachan, Leonard; Tian, Hui; Woolsey, Lauren N. 2015-01-01 Plasma in the Sun's hot corona expands into the heliosphere as a supersonic and highly magnetized solar wind. This paper provides an overview of our current understanding of how the corona is heated and how the solar wind is accelerated. Recent models of magnetohydrodynamic turbulence have progressed to the point of successfully predicting many observed properties of this complex, multi-scale system. However, it is not clear whether the heating in open-field regions comes mainly from the dissipation of turbulent fluctuations that are launched from the solar surface, or whether the chaotic ‘magnetic carpet’ in the low corona energizes the system via magnetic reconnection. To help pin down the physics, we also review some key observational results from ultraviolet spectroscopy of the collisionless outer corona. PMID:25848083 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017xru..conf..103I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017xru..conf..103I">A Systematic Search for Solar Wind Charge Exchange Emission from the Earth's Exosphere with Suzaku</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ishi, D.; Ishikawa, K.; Ezoe, Y.; Ohashi, T.; Miyoshi, Y.; Terada, N. 2017-10-01 We report on a systematic search of all the Suzaku archival data covering from 2005 August to 2015 May for geocoronal Solar Wind Charge eXchange (SWCX). In the vicinity of Earth, solar wind ions strip an electron from Earth's exospheric neutrals, emitting X-ray photons (e.g., Snowden et al. 1997). The X-ray flux of this geocoronal SWCX can change depending on solar wind condition and line of sight direction. Although it is an immediate background for all the X-ray astronomy observations, the X-ray flux prediction and the dependence on the observational conditions are not clear. Using the X-ray Imaging Spectrometer onboard Suzaku which has one of the highest sensitivities to the geocoronal SWCX, we searched the data for time variation of soft X-ray background. We then checked the solar wind proton flux taken with the WIND satellite and compared it with X-ray light curve. We also analyzed X-ray spectra and fitted them with a charge exchange emission line model constructed by Bodewits et al. (2007). Among 3055 data sets, 90 data showed SWCX features. The event rate seems to correlate with solar activity, while the distribution of SWCX events plotted in the solar magnetic coordinate system was relatively uniform. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH53A2140A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH53A2140A">Three-dimensional global MHD modeling of a coronal mass ejection interacting with the solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> An, J.; Inoue, S.; Magara, T.; Lee, H.; Kang, J.; Hayashi, K.; Tanaka, T.; Den, M. 2013-12-01 We developed a three-dimensional (3D) magnetohydrodynamic (MHD) code to reproduce the structure of the solar wind, the propagation of a coronal mass ejection (CME), and the interaction between them. This MHD code is based on the finite volume method and total diminishing (TVD) scheme with an unstructured grid system. In particular, this grid system can avoid the singularity at the north and south poles and relax tight CFL conditions around the poles, both of which would arise in the spherical coordinate system (Tanaka 1995). In this study, we constructed a model of the solar wind driven by the physical values at 50 solar radii obtained from the MHD tomographic method (Hayashi et al. 2003) where an interplanetary scintillation (IPS) observational data is used. By comparing the result to the observational data obtained from the near-Earth OMNI dataset, we confirmed that our simulation reproduces the velocity, temperature and density profiles obtained from the near-Earth OMNI dataset. We then insert a spheromak-type CME (Kataoka et al. 2009) into our solar-wind model and investigate the propagation process of the CME interacting with the solar wind. In particular, we discuss how the magnetic twist accumulated in a CME affects the CME-solar wind interaction. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030032419&hterms=corona&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dcorona','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030032419&hterms=corona&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dcorona">Three-Dimensional MHD Modeling of The Solar Corona and Solar Wind: Comparison with The Wang-Sheeley Model</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Usmanov, A. V.; Goldstein, M. L. 2003-01-01 We present simulation results from a tilted-dipole steady-state MHD model of the solar corona and solar wind and compare the output from our model with the Wang-Sheeley model which relates the divergence rate of magnetic flux tubes near the Sun (inferred from solar magnetograms) to the solar wind speed observed near Earth and at Ulysses. The boundary conditions in our model specified at the coronal base and our simulation region extends out to 10 AU. We assumed that a flux of Alfven waves with amplitude of 35 km per second emanates from the Sun and provides additional heating and acceleration for the coronal outflow in the open field regions. The waves are treated in the WKB approximation. The incorporation of wave acceleration allows us to reproduce the fast wind measurements obtained by Ulysses, while preserving reasonable agreement with plasma densities typically found at the coronal base. We find that our simulation results agree well with Wang and Sheeley's empirical model. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...859....6H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...859....6H">Structured Slow Solar Wind Variability: Streamer-blob Flux Ropes and Torsional Alfvén Waves</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Higginson, A. K.; Lynch, B. J. 2018-05-01 The slow solar wind exhibits strong variability on timescales from minutes to days, likely related to magnetic reconnection processes in the extended solar corona. Higginson et al. presented a numerical magnetohydrodynamic simulation that showed interchange magnetic reconnection is ubiquitous and most likely responsible for releasing much of the slow solar wind, in particular along topological features known as the Separatrix-Web (S-Web). Here, we continue our analysis, focusing on two specific aspects of structured slow solar wind variability. The first type is present in the slow solar wind found near the heliospheric current sheet (HCS), and the second we predict should be present everywhere S-Web slow solar wind is observed. For the first type, we examine the evolution of three-dimensional magnetic flux ropes formed at the top of the helmet streamer belt by reconnection in the HCS. For the second, we examine the simulated remote and in situ signatures of the large-scale torsional Alfvén wave (TAW), which propagates along an S-Web arc to high latitudes. We describe the similarities and differences between the reconnection-generated flux ropes in the HCS, which resemble the well-known “streamer blob” observations, and the similarly structured TAW. We discuss the implications of our results for the complexity of the HCS and surrounding plasma sheet and the potential for particle acceleration, as well as the interchange reconnection scenarios that may generate TAWs in the solar corona. We discuss predictions from our simulation results for the dynamic slow solar wind in the extended corona and inner heliosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SoSyR..51..165O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SoSyR..51..165O">On the history of the solar wind discovery</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Obridko, V. N.; Vaisberg, O. L. 2017-03-01 The discovery of the solar wind has been an outstanding achievement in heliophysics and space physics. The solar wind plays a crucial role in the processes taking place in the Solar System. In recent decades, it has been recognized as the main factor that controls the terrestrial effects of space weather. The solar wind is an unusual plasma laboratory of giant scale with a fantastic diversity of parameters and operating modes, and devoid of influence from the walls of laboratory plasma systems. It is also the only kind of stellar wind accessible for direct study. The history of this discovery is quite dramatic. Like many remarkable discoveries, it had several predecessors. However, the honor of a discovery usually belongs to a scientist who was able to more fully explain the phenomenon. Such a man is deservedly considered the US theorist Eugene Parker, who discovered the solar wind, as we know it today, almost "with the point of his pen". In 2017, we will celebrate the 90th anniversary birthday of Eugene Parker. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH11A2216M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH11A2216M">Janus: Graphical Software for Analyzing In-Situ Measurements of Solar-Wind Ions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Maruca, B.; Stevens, M. L.; Kasper, J. C.; Korreck, K. E. 2016-12-01 In-situ observations of solar-wind ions provide tremendous insights into the physics of space plasmas. Instrument on spacecraft measure distributions of ion energies, which can be processed into scientifically useful data (e.g., values for ion densities and temperatures). This analysis requires a strong, technical understanding of the instrument, so it has traditionally been carried out by the instrument teams using automated software that they had developed for that purpose. The automated routines are optimized for typical solar-wind conditions, so they can fail to capture the complex (and scientifically interesting) microphysics of transient solar-wind - such as coronal mass ejections (CME's) and co-rotating interaction regions (CIR's) - which are often better analyzed manually.This presentation reports on the ongoing development of Janus, a new software package for processing in-situ measurement of solar-wind ions. Janus will provide user with an easy-to-use graphical user interface (GUI) for carrying out highly customized analyses. Transparent to the user, Janus will automatically handle the most technical tasks (e.g., the retrieval and calibration of measurements). For the first time, users with only limited knowledge about the instruments (e.g., non-instrumentalists and students) will be able to easily process measurements of solar-wind ions. Version 1 of Janus focuses specifically on such measurements from the Wind spacecraft's Faraday Cups and is slated for public release in time for this presentation. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active">18</li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active">19</li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009eso..pres...16.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009eso..pres...16.">Solar wind tans young asteroids</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> 2009-04-01 A new study published in Nature this week reveals that asteroid surfaces age and redden much faster than previously thought -- in less than a million years, the blink of an eye for an asteroid. This study has finally confirmed that the solar wind is the most likely cause of very rapid space weathering in asteroids. This fundamental result will help astronomers relate the appearance of an asteroid to its actual history and identify any after effects of a catastrophic impact with another asteroid. ESO PR Photo 16a/09 Young Asteroids Look Old "Asteroids seem to get a ‘sun tan' very quickly," says lead author Pierre Vernazza. "But not, as for people, from an overdose of the Sun's ultraviolet radiation, but from the effects of its powerful wind." It has long been known that asteroid surfaces alter in appearance with time -- the observed asteroids are much redder than the interior of meteorites found on Earth [1] -- but the actual processes of this "space weathering" and the timescales involved were controversial. Thanks to observations of different families of asteroids [2] using ESO's New Technology Telescope at La Silla and the Very Large Telescope at Paranal, as well as telescopes in Spain and Hawaii, Vernazza's team have now solved the puzzle. When two asteroids collide, they create a family of fragments with "fresh" surfaces. The astronomers found that these newly exposed surfaces are quickly altered and change colour in less than a million years -- a very short time compared to the age of the Solar System. "The charged, fast moving particles in the solar wind damage the asteroid's surface at an amazing rate [3]", says Vernazza. Unlike human skin, which is damaged and aged by repeated overexposure to sunlight, it is, perhaps rather surprisingly, the first moments of exposure (on the timescale considered) -- the first million years -- that causes most of the aging in asteroids. By studying different families of asteroids, the team has also shown that an asteroid </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20100024507&hterms=Solar+still&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSolar%2Bstill','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20100024507&hterms=Solar+still&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSolar%2Bstill">Solar Wind Ablation of Terrestrial Planet Atmospheres</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Moore, Thomas Earle; Fok, Mei-Ching H.; Delcourt, Dominique C. 2009-01-01 Internal plasma sources usually arise in planetary magnetospheres as a product of stellar ablation processes. With the ignition of a new star and the onset of its ultraviolet and stellar wind emissions, much of the volatiles in the stellar system undergo a phase transition from gas to plasma. Condensation and accretion into a disk is replaced by radiation and stellar wind ablation of volatile materials from the system- Planets or smaller bodies that harbor intrinsic magnetic fields develop an apparent shield against direct stellar wind impact, but UV radiation still ionizes their gas phases, and the resulting internal plasmas serve to conduct currents to and from the central body along reconnected magnetic field linkages. Photoionization and thermalization of electrons warms the ionospheric topside, enhancing Jeans' escape of super-thermal particles, with ambipolar diffusion and acceleration. Moreover, observations and simulations of auroral processes at Earth indicate that solar wind energy dissipation is concentrated by the geomagnetic field by a factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Thus internal plasmas enable coupling with the plasma, neutral gas and by extension, the entire body. The stellar wind is locally loaded and slowed to develop the required power. The internal source plasma is accelerated and heated, inflating the magnetosphere as it seeks escape, and is ultimately blown away in the stellar wind. Bodies with little sensible atmosphere may still produce an exosphere of sputtered matter when exposed to direct solar wind impact. Bodies with a magnetosphere and internal sources of plasma interact more strongly with the stellar wind owing to the magnetic linkage between the two created by reconnection. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22039309-three-dimensional-magnetohydrodynamic-modeling-solar-wind-including-pickup-protons-turbulence-transport','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22039309-three-dimensional-magnetohydrodynamic-modeling-solar-wind-including-pickup-protons-turbulence-transport">THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC MODELING OF THE SOLAR WIND INCLUDING PICKUP PROTONS AND TURBULENCE TRANSPORT</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Usmanov, Arcadi V.; Matthaeus, William H.; Goldstein, Melvyn L., E-mail: arcadi.usmanov@nasa.gov 2012-07-20 To study the effects of interstellar pickup protons and turbulence on the structure and dynamics of the solar wind, we have developed a fully three-dimensional magnetohydrodynamic solar wind model that treats interstellar pickup protons as a separate fluid and incorporates the transport of turbulence and turbulent heating. The governing system of equations combines the mean-field equations for the solar wind plasma, magnetic field, and pickup protons and the turbulence transport equations for the turbulent energy, normalized cross-helicity, and correlation length. The model equations account for photoionization of interstellar hydrogen atoms and their charge exchange with solar wind protons, energy transfermore » from pickup protons to solar wind protons, and plasma heating by turbulent dissipation. Separate mass and energy equations are used for the solar wind and pickup protons, though a single momentum equation is employed under the assumption that the pickup protons are comoving with the solar wind protons. We compute the global structure of the solar wind plasma, magnetic field, and turbulence in the region from 0.3 to 100 AU for a source magnetic dipole on the Sun tilted by 0 Degree-Sign -90 Degree-Sign and compare our results with Voyager 2 observations. The results computed with and without pickup protons are superposed to evaluate quantitatively the deceleration and heating effects of pickup protons, the overall compression of the magnetic field in the outer heliosphere caused by deceleration, and the weakening of corotating interaction regions by the thermal pressure of pickup protons.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..MARV31015P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..MARV31015P">Analysis of Wind Forces on Roof-Top Solar Panel</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Panta, Yogendra; Kudav, Ganesh 2011-03-01 Structural loads on solar panels include forces due to high wind, gravity, thermal expansion, and earthquakes. International Building Code (IBC) and the American Society of Civil Engineers are two commonly used approaches in solar industries to address wind loads. Minimum Design Loads for Buildings and Other Structures (ASCE 7-02) can be used to calculate wind uplift loads on roof-mounted solar panels. The present study is primarily focused on 2D and 3D modeling with steady, and turbulent flow over an inclined solar panel on the flat based roof to predict the wind forces for designing wind management system. For the numerical simulation, 3-D incompressible flow with the standard k- ɛ was adopted and commercial CFD software ANSYS FLUENT was used. Results were then validated with wind tunnel experiments with a good agreement. Solar panels with various aspect ratios for various high wind speeds and angle of attacks were modeled and simulated in order to predict the wind loads in various scenarios. The present study concluded to reduce the strong wind uplift by designing a guide plate or a deflector before the panel. Acknowledgments to Northern States Metal Inc., OH (GK & YP) and School of Graduate Studies of YSU for RP & URC 2009-2010 (YP). </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663613-kinetic-slow-modes-fluid-slow-modes-pressure-balanced-structures-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663613-kinetic-slow-modes-fluid-slow-modes-pressure-balanced-structures-solar-wind">On Kinetic Slow Modes, Fluid Slow Modes, and Pressure-balanced Structures in the Solar Wind</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Verscharen, Daniel; Chen, Christopher H. K.; Wicks, Robert T., E-mail: daniel.verscharen@unh.edu, E-mail: christopher.chen@imperial.ac.uk, E-mail: r.wicks@ucl.ac.uk Observations in the solar wind suggest that the compressive component of inertial-range solar-wind turbulence is dominated by slow modes. The low collisionality of the solar wind allows for nonthermal features to survive, which suggests the requirement of a kinetic plasma description. The least-damped kinetic slow mode is associated with the ion-acoustic (IA) wave and a nonpropagating (NP) mode. We derive analytical expressions for the IA-wave dispersion relation in an anisotropic plasma in the framework of gyrokinetics and then compare them to fully kinetic numerical calculations, results from two-fluid theory, and magnetohydrodynamics (MHD). This comparison shows major discrepancies in the predictedmore » wave phase speeds from MHD and kinetic theory at moderate to high β . MHD and kinetic theory also dictate that all plasma normal modes exhibit a unique signature in terms of their polarization. We quantify the relative amplitude of fluctuations in the three lowest particle velocity moments associated with IA and NP modes in the gyrokinetic limit and compare these predictions with MHD results and in situ observations of the solar-wind turbulence. The agreement between the observations of the wave polarization and our MHD predictions is better than the kinetic predictions, which suggests that the plasma behaves more like a fluid in the solar wind than expected.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSH51B2227S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSH51B2227S">Nature of Kinetic Scale Fluctuations in Solar Wind Turbulence</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Salem, C. S.; Chen, C. H.; Sundkvist, D. J.; Chaston, C. C.; Bale, S. D.; Mozer, F. 2012-12-01 We present an investigation of the nature of small-scale turbulent fluctuations in the solar wind. The nature of the dissipation range fluctuations of solar wind turbulence remains a major open question in heliospheric physics. The steepening of the observed (magnetic field) spectra at ion scales was originally attributed to ion cyclotron damping, but it was later suggested that it could well be due to the dispersive nature of fluctuations at these scales. The nature of the dispersive cascade at and below the ion scales is still debated, two leading hypothesis being that these fluctuations have characteristics of Kinetic Alfven Waves (KAW) or whistler waves. Other possible contributions from current sheets and/or kinetic instabilities have been suggested. There is mounting evidence that the fluctuations at these scales are KAW-like. In this study, we analyze several carefully selected unperturbed solar wind intervals, using magnetic field, electric field as well as density measurements from the Cluster spacecraft in order to identify the nature of the wave modes present, how frequent they are and try to determine whether one or more wave modes at different times. We examine the electric to magnetic field fluctuation ratio (δ E/δd B), the magnetic compressibility (δ B∥ /δ B) as well as density fluctuations using newly developed diagnostic techniques by Salem et al (2012) and Chen et al (2012). We look for variations of the nature and properties of these kinetic scale fluctuations with solar wind conditions, such as the plasma beta and the angle between the magnetic field and the flow velocity which controls the measured (spacecraft frame) frequency of the fluctuations. We discuss how these results would impact how the solar wind plasma is heated. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040111086','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040111086">Simulations of Solar Wind Plasma Flow Around a Simple Solar Sail</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Garrett, Henry B.; Wang, Joseph 2004-01-01 In recent years, a number of solar sail missions of various designs and sizes have been proposed (e.g., Geostorm). Of importance to these missions is the interaction between the ambient solar wind plasma environment and the sail. Assuming a typical 1 AU solar wind environment of 400 km/s velocity, 3.5 cu cm density, ion temperature of approx.10 eV, electron temperature of 40 eV, and an ambient magnetic field strength of 10(exp -4) G, a first order estimate of the plasma interaction with square solar sails on the order of the sizes being considered for a Geostorm mission (50 m x 50 m and 75 m x 75 m corresponding to approx.2 and approx.3 times the Debye length in the plasma) is carried out. First, a crude current balance for the sail surface immersed in the plasma environment and in sunlight was used to estimate the surface potential of the model sails. This gave surface potentials of approx.10 V positive relative to the solar wind plasma. A 3-D, Electrostatic Particle-in-Cell (PIC) code was then used to simulate the solar wind flowing around the solar sail. It is assumed in the code that the solar wind protons can be treated as particles while the electrons follow a Boltzmann distribution. Next, the electric field and particle trajectories are solved self-consistently to give the proton flow field, the electrostatic field around the sail, and the plasma density in 3-D. The model sail was found to be surrounded by a plasma sheath within which the potential is positive compared to the ambient plasma and followed by a separate plasma wake which is negative relative to the plasma. This structure departs dramatically from a negatively charged plate such as might be found in the Earth s ionosphere on the night side where both the plate and its negative wake are contiguous. The implications of these findings are discussed as they apply to the proposed Geostorm solar sail mission. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730002049','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730002049">Average thermal characteristics of solar wind electrons</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Montgomery, M. D. 1972-01-01 Average solar wind electron properties based on a 1 year Vela 4 data sample-from May 1967 to May 1968 are presented. Frequency distributions of electron-to-ion temperature ratio, electron thermal anisotropy, and thermal energy flux are presented. The resulting evidence concerning heat transport in the solar wind is discussed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH14B..06W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH14B..06W">How Well Can the Observed Flux Ropes in the Solar Wind be Fitted by a Uniform-twist Flux Rope Model?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wang, Y. 2015-12-01 In the solar wind, flux ropes, e.g., magnetic clouds (MCs), are a frequently observational phenomenon. Their magnetic field configuration or the way that the field lines wind around the flux rope axis is one of the most important information to understand the formation and evolution of the observed flux ropes. Most MCs are believed to be in the force-free state, and widely modeled by the Lundquist force-free solution, in which the twist of the field line increases from zero at the axis to infinity at the boundary. However, Lundquist solution is not the only form of a force-free magnetic field. Some studies based on suprathermal electron observations and models have shown that MCs may carry magnetic field lines more likely to be uniformly twisted. The nonlinear force-free field extrapolation of solar magnetic field also suggests that the field lines of a flux rope twist limitedly. In this study, we have developed a velocity-modified uniform-twist force-free flux rope model, and fit observed MCs with this model. By using this approach, we test how well the observed MCs can be fitted into a uniform-twist flux rope. Some interesting results will be given in this presentation. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22518676-evolution-intermittency-slow-fast-solar-wind-beyond-ecliptic-plane','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22518676-evolution-intermittency-slow-fast-solar-wind-beyond-ecliptic-plane">EVOLUTION OF INTERMITTENCY IN THE SLOW AND FAST SOLAR WIND BEYOND THE ECLIPTIC PLANE</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Wawrzaszek, A.; Macek, W. M.; Echim, M. 2015-12-01 We study intermittency as a departure from self-similarity of the solar wind magnetic turbulence and investigate the evolution with the heliocentric distance and latitude. We use data from the Ulysses spacecraft measured during two solar minima (1997–1998 and 2007–2008) and one solar maximum (1999–2001). In particular, by modeling a multifractal spectrum, we revealed the intermittent character of turbulence in the small-scale fluctuations of the magnetic field embedded in the slow and fast solar wind. Generally, at small distances from the Sun, in both the slow and fast solar wind, we observe the high degree of multifractality (intermittency) that decreases somewhatmore » slowly with distance and slowly with latitude. The obtained results seem to suggest that generally intermittency in the solar wind has a solar origin. However, the fast and slow streams, shocks, and other nonlinear interactions can only be considered as the drivers of the intermittent turbulence. It seems that analysis shows that turbulence beyond the ecliptic plane evolves too slowly to maintain the intermittency with the distance and latitude. Moreover, we confirm that the multifractality and intermittency are at a lower level than in the ecliptic, as well as the existence of symmetry with respect to the ecliptic plane, suggesting that there are similar turbulent properties observed in the two hemispheres.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1215020','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1215020">Role of Concentrating Solar Power in Integrating Solar and Wind Energy: Preprint</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Denholm, P.; Mehos, M. 2015-06-03 As wind and solar photovoltaics (PV) increase in penetration it is increasingly important to examine enabling technologies that can help integrate these resources at large scale. Concentrating solar power (CSP) when deployed with thermal energy storage (TES) can provide multiple services that can help integrate variable generation (VG) resources such as wind and PV. CSP with TES can provide firm, highly flexible capacity, reducing minimum generation constraints which limit penetration and results in curtailment. By acting as an enabling technology, CSP can complement PV and wind, substantially increasing their penetration in locations with adequate solar resource. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SSRv..195..125H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SSRv..195..125H">The Solar Wind Ion Analyzer for MAVEN</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Halekas, J. S.; Taylor, E. R.; Dalton, G.; Johnson, G.; Curtis, D. W.; McFadden, J. P.; Mitchell, D. L.; Lin, R. P.; Jakosky, B. M. 2015-12-01 The Solar Wind Ion Analyzer (SWIA) on the MAVEN mission will measure the solar wind ion flows around Mars, both in the upstream solar wind and in the magneto-sheath and tail regions inside the bow shock. The solar wind flux provides one of the key energy inputs that can drive atmospheric escape from the Martian system, as well as in part controlling the structure of the magnetosphere through which non-thermal ion escape must take place. SWIA measurements contribute to the top level MAVEN goals of characterizing the upper atmosphere and the processes that operate there, and parameterizing the escape of atmospheric gases to extrapolate the total loss to space throughout Mars' history. To accomplish these goals, SWIA utilizes a toroidal energy analyzer with electrostatic deflectors to provide a broad 360∘×90∘ field of view on a 3-axis spacecraft, with a mechanical attenuator to enable a very high dynamic range. SWIA provides high cadence measurements of ion velocity distributions with high energy resolution (14.5 %) and angular resolution (3.75∘×4.5∘ in the sunward direction, 22.5∘×22.5∘ elsewhere), and a broad energy range of 5 eV to 25 keV. Onboard computation of bulk moments and energy spectra enable measurements of the basic properties of the solar wind at 0.25 Hz. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740010336&hterms=heavy+metals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dheavy%2Bmetals','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740010336&hterms=heavy+metals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dheavy%2Bmetals">Measurements of heavy solar wind and higher energy solar particles during the Apollo 17 mission</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Walker, R. M.; Zinner, E.; Maurette, M. 1973-01-01 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 solar wind ions in the sample exposed directly to the sun. The initial results indicate a depletion of very-heavy solar wind ions. The effect is probably not real but is caused by scanning inefficiencies. Despite the lack of any pronounced solar 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110015175','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110015175">Sputtering by the Solar Wind: Effects of Variable Composition</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Killen, R. M.; Arrell, W. M.; Sarantos, M.; Delory, G. T. 2011-01-01 It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that there is no increase in the sputtering yield caused by highly charged heavy ions for metallic and for semiconducting surfaces, but the sputter yield can be noticeably increased in the case of a good insulating surface. Recently measurements of the solar wind composition have become available. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. Whereas many previous calculations of sputtering were limited to the effects of proton bombardment. we show that the heavy ion component. especially the He++ component. can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. We will discuss sputtering of both neutrals and ions. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPD....47.0324P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPD....47.0324P">Morphology of Pseudostreamers and Solar Wind Properties</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Panasenco, Olga; Velli, Marco 2016-05-01 The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop the specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates the conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Middle-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers (PSs) if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of PSs shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at the PS base low in the corona. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...835..133S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...835..133S">A Model for Dissipation of Solar Wind Magnetic Turbulence by Kinetic Alfvén Waves at Electron Scales: Comparison with Observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Schreiner, Anne; Saur, Joachim 2017-02-01 In hydrodynamic turbulence, it is well established that the length of the dissipation scale depends on the energy cascade rate, I.e., the larger the energy input rate per unit mass, the more the turbulent fluctuations need to be driven to increasingly smaller scales to dissipate the larger energy flux. Observations of magnetic spectral energy densities indicate that this intuitive picture is not valid in solar wind turbulence. Dissipation seems to set in at the same length scale for different solar wind conditions independently of the energy flux. To investigate this difference in more detail, we present an analytic dissipation model for solar wind turbulence at electron scales, which we compare with observed spectral densities. Our model combines the energy transport from large to small scales and collisionless damping, which removes energy from the magnetic fluctuations in the kinetic regime. We assume wave-particle interactions of kinetic Alfvén waves (KAWs) to be the main damping process. Wave frequencies and damping rates of KAWs are obtained from the hot plasma dispersion relation. Our model assumes a critically balanced turbulence, where larger energy cascade rates excite larger parallel wavenumbers for a certain perpendicular wavenumber. If the dissipation is additionally wave driven such that the dissipation rate is proportional to the parallel wavenumber—as with KAWs—then an increase of the energy cascade rate is counterbalanced by an increased dissipation rate for the same perpendicular wavenumber, leading to a dissipation length independent of the energy cascade rate. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.2973B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.2973B">Substorm occurrence rates, substorm recurrence times, and solar wind structure</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Borovsky, Joseph E.; Yakymenko, Kateryna 2017-03-01 Two collections of substorms are created: 28,464 substorms identified with jumps in the SuperMAG AL index in the years 1979-2015 and 16,025 substorms identified with electron injections into geosynchronous orbit in the years 1989-2007. Substorm occurrence rates and substorm recurrence-time distributions are examined as functions of the phase of the solar cycle, the season of the year, the Russell-McPherron favorability, the type of solar wind plasma at Earth, the geomagnetic-activity level, and as functions of various solar and solar wind properties. Three populations of substorm occurrences are seen: (1) quasiperiodically occurring substorms with recurrence times (waiting times) of 2-4 h, (2) randomly occurring substorms with recurrence times of about 6-15 h, and (3) long intervals wherein no substorms occur. A working model is suggested wherein (1) the period of periodic substorms is set by the magnetosphere with variations in the actual recurrence times caused by the need for a solar wind driving interval to occur, (2) the mesoscale structure of the solar wind magnetic field triggers the occurrence of the random substorms, and (3) the large-scale structure of the solar wind plasma is responsible for the long intervals wherein no substorms occur. Statistically, the recurrence period of periodically occurring substorms is slightly shorter when the ram pressure of the solar wind is high, when the magnetic field strength of the solar wind is strong, when the Mach number of the solar wind is low, and when the polar-cap potential saturation parameter is high. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.nrel.gov/grid/hawaii-integration-studies.html','SCIGOVWS'); return false;" href="https://www.nrel.gov/grid/hawaii-integration-studies.html">Hawaii Solar and Wind Integration Studies | Grid Modernization | NREL</a> <a target="_blank" href="http://www.science.gov/aboutsearch.html">Science.gov Websites</a> Solar Integration Study and Oahu Wind Integration and Transmission Study investigated the effects of high penetrations of renewables on island grids. Hawaii Solar Integration Study The Hawaii Solar Integration Study was a detailed technical examination of the effects of high penetrations of solar and wind </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090006630&hterms=figueroa&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfigueroa','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090006630&hterms=figueroa&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfigueroa">Variations of Strahl Properties with Fast and Slow Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Figueroa-Vinas, Adolfo; Goldstein, Melvyn L.; Gurgiolo, Chris 2008-01-01 The interplanetary solar wind electron velocity distribution function generally shows three different populations. Two of the components, the core and halo, have been the most intensively analyzed and modeled populations using different theoretical models. The third component, the strahl, is usually seen at higher energies, is confined in pitch-angle, is highly field-aligned and skew. This population has been more difficult to identify and to model in the solar wind. In this work we make use of the high angular, energy and time resolution and three-dimensional data of the Cluster/PEACE electron spectrometer to identify and analyze this component in the ambient solar wind during high and slow speed solar wind. The moment density and fluid velocity have been computed by a semi-numerical integration method. The variations of solar wind density and drift velocity with the general build solar wind speed could provide some insight into the source, origin, and evolution of the strahl. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910047213&hterms=radiation+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dradiation%2BSolar','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910047213&hterms=radiation+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dradiation%2BSolar">Erosion of carbon/carbon by solar wind charged particle radiation during a solar probe mission</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sokolowski, Witold; O'Donnell, Tim; Millard, Jerry 1991-01-01 The possible erosion of a carbon/carbon thermal shield by solar wind-charged particle radiation is reviewed. The present knowledge of erosion data for carbon and/or graphite is surveyed, and an explanation of erosion mechanisms under different charged particle environments is discussed. The highest erosion is expected at four solar radii. Erosion rates are analytically estimated under several conservative assumptions for a normal quiet and worst case solar wind storm conditions. Mass loss analyses and comparison studies surprisingly indicate that the predicted erosion rate by solar wind could be greater than by nominal free sublimation during solar wind storm conditions at four solar radii. The predicted overall mass loss of a carbon/carbon shield material during the critical four solar radii flyby can still meet the mass loss mission requirement of less than 0.0025 g/sec. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active">19</li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active">20</li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <a target="_blank" onclick="trackOutboundLink('https://www.nrel.gov/news/press/1997/56stocksh.html','SCIGOVWS'); return false;" href="https://www.nrel.gov/news/press/1997/56stocksh.html">Free Consumer Workshops On Solar & Wind Power</a> <a target="_blank" href="http://www.science.gov/aboutsearch.html">Science.gov Websites</a> Free Consumer Workshops On Solar & Wind Power For Farm & Ranch At National Western Stock three free consumer workshops on solar and wind power for the farm and ranch at the 1998 National information booth in the Stock Show's Hall of Education. Free literature on renewable energy is available at </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SoPh..292...69O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SoPh..292...69O">Probabilistic Solar Wind and Geomagnetic Forecasting Using an Analogue Ensemble or "Similar Day" Approach</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Owens, M. J.; Riley, P.; Horbury, T. S. 2017-05-01 Effective space-weather prediction and mitigation requires accurate forecasting of near-Earth solar-wind conditions. Numerical magnetohydrodynamic models of the solar wind, driven by remote solar observations, are gaining skill at forecasting the large-scale solar-wind features that give rise to near-Earth variations over days and weeks. There remains a need for accurate short-term (hours to days) solar-wind forecasts, however. In this study we investigate the analogue ensemble (AnEn), or "similar day", approach that was developed for atmospheric weather forecasting. The central premise of the AnEn is that past variations that are analogous or similar to current conditions can be used to provide a good estimate of future variations. By considering an ensemble of past analogues, the AnEn forecast is inherently probabilistic and provides a measure of the forecast uncertainty. We show that forecasts of solar-wind speed can be improved by considering both speed and density when determining past analogues, whereas forecasts of the out-of-ecliptic magnetic field [BN] are improved by also considering the in-ecliptic magnetic-field components. In general, the best forecasts are found by considering only the previous 6 - 12 hours of observations. Using these parameters, the AnEn provides a valuable probabilistic forecast for solar-wind speed, density, and in-ecliptic magnetic field over lead times from a few hours to around four days. For BN, which is central to space-weather disturbance, the AnEn only provides a valuable forecast out to around six to seven hours. As the inherent predictability of this parameter is low, this is still likely a marked improvement over other forecast methods. We also investigate the use of the AnEn in forecasting geomagnetic indices Dst and Kp. The AnEn provides a valuable probabilistic forecast of both indices out to around four days. We outline a number of future improvements to AnEn forecasts of near-Earth solar-wind and geomagnetic </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160005855&hterms=density&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddensity','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160005855&hterms=density&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddensity">Periodic Density Structures and the Origin of the Slow Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Viall-Kepko, Nicholeen M.; Vourlidas, Angelos 2015-01-01 The source of the slow solar wind has challenged scientists for years. Periodic density structures (PDSs), observed regularly in the solar wind at 1 AU (Astronomical Unit), can be used to address this challenge. These structures have length scales of hundreds to several thousands of megameters and frequencies of tens to hundreds of minutes. Two lines of evidence indicate that PDSs are formed in the solar corona as part of the slow solar wind release and/or acceleration processes. The first is corresponding changes in compositional data in situ, and the second is PDSs observed in the inner Heliospheric Imaging data on board the Solar Terrestrial Relations Observatory (STEREO)/Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) suite. The periodic nature of these density structures is both a useful identifier as well as an important physical constraint on their origin. In this paper, we present the results of tracking periodic structures identified in the inner Heliospheric Imager in SECCHI back in time through the corresponding outer coronagraph (COR2) images. We demonstrate that the PDSs are formed around or below 2.5 solar radii-the inner edge of the COR2 field of view. We compute the occurrence rates of PDSs in 10 days of COR2 images both as a function of their periodicity and location in the solar corona, and we find that this set of PDSs occurs preferentially with a periodicity of approximately 90 minutes and occurs near streamers. Lastly, we show that their acceleration and expansion through COR2 is self-similar, thus their frequency is constant at distances beyond 2.5 solar radii. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH14A..07Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH14A..07Z">Local Equation of State for Protons, and Implications for Proton Heating in the Solar Wind.</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zaslavsky, A.; Maksimovic, M.; Kasper, J. C. 2017-12-01 The solar wind protons temperature is observed to decrease with distance to the Sun at a slower rate than expected from an adiabatic expansion law: the protons are therefore said to be heated. This observation raises the question of the evaluation of the heating rate, and the question of the heat source.These questions have been investigated by previous authors by gathering proton data on various distances to the Sun, using spacecraft as Helios or Ulysses, and then computing the radial derivative of the proton temperature in order to obtain a heating rate from the internal energy equation. The problem of such an approach is the computation of the radial derivative of the temperature profile, for which uncertainties are very large, given the dispersion of the temperatures measured at a given distance.An alternative approach, that we develop in this paper, consists in looking for an equation of state that links locally the pressure (or temperature) to the mass density. If such a relation exists then one can evaluate the proton heating rate on a local basis, without having any space derivative to compute.Here we use several years of STEREO and WIND proton data to search for polytropic equation of state. We show that such relationships are indeed a good approximation in given solar wind's velocity intervals and deduce the associated protons heating rates as a function of solar wind's speed. The obtained heating rates are shown to scale from around 1 kW/kg in the slow wind to around 10 kW/kg in the fast wind, in remarkable agreement with the rate of energy observed by previous authors to cascade in solar wind's MHD turbulence at 1 AU. These results therefore support the idea of proton turbulent heating in the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH32A..01K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH32A..01K">Understanding non-equilibrium collisional and expansion effects in the solar wind with Parker Solar Probe</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Korreck, K. E.; Klein, K. G.; Maruca, B.; Alterman, B. L. 2017-12-01 The evolution of the solar wind from the corona to the Earth and throughout the heliosphere is a complex interplay between local micro kinetics and large scale expansion effects. These processes in the solar wind need to be separated in order to understand and distinguish the dominant mechanism for heating and acceleration of the solar wind. With the upcoming launch in 2018 of Parker Solar Probe and the launch of Solar Orbiter after, addressing the local and global phenomena will be enabled with in situ measurements. Parker Solar Probe will go closer to the Sun than any previous mission enabling the ability to examine the solar wind at an early expansion age. This work examines the predictions for what will be seen inside of the 0.25 AU (54 solar radii) where Parker Solar Probe will take measurements and lays the groundwork for disentangling the expansion and collisional effects. In addition, methods of thermal plasma data analysis to determine the stability of the plasma in the Parker Solar Probe measurements will be discussed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720003183','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720003183">Dynamics of the solar wind and its interaction with bodies in the solar system</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spreiter, J. R. 1971-01-01 A discussion of the solar wind and its interaction with bodies of the solar system is presented. An overall unified account of the role of shock waves in the heating of the solar corona, the transmission of solar disturbances to the solar system, the flow fields of planets and natural satellites, and biological effects are provided. An analysis of magnetometer data from Explorer 33 and Vela 3A satellites to identify characteristics of solar wind shock waves is included. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPSC...11..899A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPSC...11..899A">Modelling Magnetodisc Response to Solar Wind Events</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Achilleos, N.; Guio, P.; Arridge, C. S. 2017-09-01 The Sun's influence is felt by planets in the solar system in many different ways. In this work, we use theoretical models of the magnetic fields of the Gas Giants (Jupiter and Saturn) to predict how they would change in response to compressions and expansions in the flow of charged particles ('solar wind') which continually emanates from the Sun. This in an example of 'Space Weather' - the interaction between the solar wind and magnetized planets, such as Jupiter, Saturn and even the Earth. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040171195','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040171195">Identification of Interplanetary Coronal Mass Ejections at 1 AU Using Multiple Solar Wind Plasma Composition Anomalies</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Richardson, I. G.; Cane, H. V. 2004-01-01 We investigate the use of multiple simultaneous solar wind plasma compositional anomalies, relative to the composition of the ambient solar wind, for identifying interplanetary coronal mass ejection (ICME) plasma. We first summarize the characteristics of several solar wind plasma composition signatures (O(+7)/O(+6), Mg/O, Ne/O, Fe charge states, He/p) observed by the ACE and WIND spacecraft within the ICMEs during 1996 - 2002 identsed by Cane and Richardson. We then develop a set of simple criteria that may be used to identify such compositional anomalies, and hence potential ICMEs. To distinguish these anomalies from the normal variations seen in ambient solar wind composition, which depend on the wind speed, we compare observed compositional signatures with those 'expected' in ambient solar wind with the same solar wind speed. This method identifies anomalies more effectively than the use of fixed thresholds. The occurrence rates of individual composition anomalies within ICMEs range from approx. 70% for enhanced iron and oxygen charge states to approx. 30% for enhanced He/p (> 0.06) and Ne/O, and are generally higher in magnetic clouds than other ICMEs. Intervals of multiple anomalies are usually associated with ICMEs, and provide a basis for the identification of the majority of ICMEs. We estimate that Cane and Richardson, who did not refer to composition data, probably identitied approx. 90% of the ICMEs present. However, around 10% of their ICMEs have weak compositional anomalies, suggesting that the presence of such signatures does not provide a necessary requirement for an ICME. We note a remarkably similar correlation between the Mg/O and O(7)/O(6) ratios in hourly-averaged data both within ICMEs and the ambient solar wind. This 'universal' relationship suggests that a similar process (such as minor ion heating by waves inside coronal magnetic field loops) produces the first-ionization potential bias and ion freezing-in temperatures in the source regions </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM23A2466U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM23A2466U">Leveraging the Polar Cap: Ground-Based Measurements of the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Urban, K. D.; Gerrard, A. J.; Weatherwax, A. T.; Lanzerotti, L. J.; Patterson, J. D. 2016-12-01 In this study, we look at and identify relationships between solar wind quantities that have previously been shown to have direct access into the very high-latitude polar cap as measured by ground-based riometers and magnetometers in Antarctica: ultra-low frequency (ULF) power in the interplanetary magnetic field (IMF) Bz component and solar energetic proton (SEP) flux (Urban [2016] and Patterson et al. [2001], respectively). It is shown that such solar wind and ground-based observations can be used to infer the hydromagnetic structure and magnetospheric mapping of the polar cap region in a data-driven manner, and that high-latitude ground-based instrumentation can be used to infer concurrent various state parameters of the geospace environment. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUSM..SM32D03K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUSM..SM32D03K">Does Solar Wind also Drive Convection in Jupiter's Magnetosphere?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Khurana, K. K. 2001-05-01 Using a simple model of magnetic field and plasma velocity, Brice and Ioannidis [1970] showed that the corotation electric field exceeds convection electric field throughout the Jovian magnetosphere. Since that time it has been tacitly assumed that Jupiter's magnetosphere is driven from within. If Brice and Ioannidis conjecture is correct then one would not expect major asymmetries in the field and plasma parameters in the middle magnetosphere of Jupiter. Yet, new field and plasma observations from Galileo and simultaneous auroral observations from HST show that there are large dawn/dusk and day/night asymmetries in many magnetospheric parameters. For example, the magnetic observations show that a partial ring current and an associated Region-2 type field-aligned current system exist in the magnetosphere of Jupiter. In the Earth's magnetosphere it is well known that the region-2 current system is created by the asymmetries imposed by a solar wind driven convection. Thus, we are getting first hints that the solar wind driven convection is important in Jupiter's magnetosphere as well. Other in-situ observations also point to dawn-dusk asymmetries imposed by the solar wind. For example, first order anisotropies in the Energetic Particle Detector show that the plasma is close to corotational on the dawn side but lags behind corotation in the dusk sector. Magnetic field data show that the current sheet is thin and highly organized on the dawn side but thick and disturbed on the dusk side. I will discuss the reasons why Brice and Ioannidis calculation may not be valid. I will show that both the magnetic field and plasma velocity estimates used by Brice and Ioannidis were rather excessive. Using more modern estimates of the field and velocity values I show that the solar wind convection can penetrate as deep as 40 RJ on the dawnside. I will present a new model of convection that invokes in addition to a distant neutral line spanning the whole magnetotail, a near </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ChA%26A..41..517S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ChA%26A..41..517S">Influence of Convective Effect of Solar Winds on the CME Transit Time</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sun, Lu-yuan 2017-10-01 Based on an empirical model for predicting the transit time of coronal mass ejections (CMEs) proposed by Gopalswamy, 52 CME events which are related to the geomagnetic storms of Dst < -50 nT, and 10 CME events which caused extremely strong geomagnetic storms (Dst < -200 nT) in 1996- 2007 are selected, and combined with the observational data of the interplanetary solar winds that collected by the ACE satellite at 1AU, to analyze the influence of convective effect of ambient solar winds on the prediction of the CME transit time when it arrives at a place of 1 AU. After taking the convective effect of ambient solar winds into account, the standard deviation of predictions is reduced from 16.5 to 11.4 hours for the 52 CME events, and the prediction error is less than 15 hours for 68% of these events; while the standard deviation of predictions is reduced from 10.6 to 6.5 hours for the 10 CME events that caused extremely strong geomagnetic storms, and the prediction error is less than 5 hours for 6 of the 10 events. These results show that taking the convective effect of ambient solar winds into account can reduce the standard deviation of the predicted CME transit time, hence the convective effect of solar winds plays an important role for predicting the transit times of CME events. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.......116T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.......116T">In-situ Plasma Analysis of Ion Kinetics in the Solar Wind and Hermean Magnetosphere</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tracy, Patrick J. The heating of the solar wind and its interaction with the unique planetary magnetosphere of Mercury is the primary focus of this work. The first aspect of this study focused on the heavy ion population of the solar wind (A > 4 amu), and how well the signature of the heating process responsible for creating the solar wind is preserved in this heavy ion population. We found that this signature in the heavy ion population is primarily erased (thermalized) via Coulomb collisional interactions with solar wind protons. The heavy ions observed in collisionally young solar wind reveal a clear, stable dependence on mass, along with non-thermal heating that is not in agreement with current predictions based on turbulent transport and kinetic dissipation. Due to its weak magnetic dipole, the solar wind can impinge on the surface of Mercury, one of the processes contributing to the desorption of neutrals and, through ionization, ions that make up the planet's exosphere. Differentiating between surface mechanisms and analyzing magnetospheric plasma dynamics requires the quantification of a variety of ion species. A detailed forward model and a robust statistical method were created to identify new ion signatures in the measurement space of the FIPS instrument, formerly orbiting Mercury onboard the MESSENGER spacecraft. The recovery of new heavy ions species, including Al, Ne, Si, and Mg, along with tentative recoveries of S, Ar, K, and C, enable in depth studies of the plasma dynamics in the Hermean magnetosphere. The interaction of the solar wind with the bow shock of the Hermean magnetosphere leads to the creation of a foreshock region. New tools and methods were created to enable the analysis of the diffuse and Field Aligned Beam (FAB) populations in unique parameter regime of the Hermean foreshock. One result suggests that the energization process for the observed FABs can be explained by Shock Drift Acceleration, and not limited by the small spatial size of Mercury's bow </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070021568&hterms=solar+energy+advantage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Benergy%2Badvantage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070021568&hterms=solar+energy+advantage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Benergy%2Badvantage">Measurement of Damage Profiles from Solar Wind Implantation</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> McNamara, K. M.; Synowicki, R. A.; Tiwald, T. E. 2007-01-01 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 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45..585L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45..585L">Prompt Disappearance and Emergence of Radiation Belt Magnetosonic Waves Induced by Solar Wind Dynamic Pressure Variations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Liu, Nigang; Su, Zhenpeng; Zheng, Huinan; Wang, Yuming; Wang, Shui 2018-01-01 Magnetosonic waves are highly oblique whistler mode emissions transferring energy from the ring current protons to the radiation belt electrons in the inner magnetosphere. Here we present the first report of prompt disappearance and emergence of magnetosonic waves induced by the solar wind dynamic pressure variations. The solar wind dynamic pressure reduction caused the magnetosphere expansion, adiabatically decelerated the ring current protons for the Bernstein mode instability, and produced the prompt disappearance of magnetosonic waves. On the contrary, because of the adiabatic acceleration of the ring current protons by the solar wind dynamic pressure enhancement, magnetosonic waves emerged suddenly. In the absence of impulsive injections of hot protons, magnetosonic waves were observable even only during the time period with the enhanced solar wind dynamic pressure. Our results demonstrate that the solar wind dynamic pressure is an essential parameter for modeling of magnetosonic waves and their effect on the radiation belt electrons. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM51F4331H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM51F4331H">Mini-Magnetospheres at the Moon in the Solar Wind and the Earth's Plasma Sheet</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Harada, Y.; Futaana, Y.; Barabash, S. V.; Wieser, M.; Wurz, P.; Bhardwaj, A.; Asamura, K.; Saito, Y.; Yokota, S.; Tsunakawa, H.; Machida, S. 2014-12-01 Lunar mini-magnetospheres are formed as a consequence of solar-wind interaction with remanent crustal magnetization on the Moon. A variety of plasma and field perturbations have been observed in a vicinity of the lunar magnetic anomalies, including electron energization, ion reflection/deflection, magnetic field enhancements, electrostatic and electromagnetic wave activities, and low-altitude ion deceleration and electron acceleration. Recent Chandrayaan-1 observations of the backscattered energetic neutral atoms (ENAs) from the Moon in the solar wind revealed upward ENA flux depletion (and thus depletion of the proton flux impinging on the lunar surface) in association with strongly magnetized regions. These ENA observations demonstrate that the lunar surface is shielded from the solar wind protons by the crustal magnetic fields. On the other hand, when the Moon was located in the Earth's plasma sheet, no significant depletion of the backscattered ENA flux was observed above the large and strong magnetic anomaly. It suggests less effective magnetic shielding of the surface from the plasma sheet protons than from the solar wind protons. We conduct test-particle simulations showing that protons with a broad velocity distribution are more likely to reach a strongly magnetized surface than those with a beam-like velocity distribution. The ENA observations together with the simulation results suggest that the lunar crustal magnetic fields are no longer capable of standing off the ambient plasma when the Moon is immersed in the hot magnetospheric plasma. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH42A..01O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH42A..01O">Fundamental Physics of the Slow Solar Wind - What do we Know?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ofman, L.; Abbo, L.; Antiochos, S. K.; Hansteen, V. H.; Harra, L.; Ko, Y. K.; Lapenta, G.; Li, B.; Riley, P.; Strachan, L.; von Steiger, R.; Wang, Y. M. 2016-12-01 Fundamental physical properties of the slow solar wind (SSW), such as density, temperature, outflow speed, heavy ion abundances and charges states were obtained from in-situ measurements at 1AU in the past from WIND, ACE, and other spacecraft. Plasma and magnetic field measurement are available as close as 0.3 AU from Helios data, Spektr-R, and MESSENGER spacecraft. Remote sensing spectroscopic measurements are available in the corona and below from SOHO/UVCS, Hinode, and other missions. One of the major objectives of the Solar Orbiter and Solar Probe Plus missions is to study the sources of the SSW close to the Sun. The present state of understanding of the physics of the SSW is based on the combination of the existing observations, theoretical and numerical 3D MHD and multi-fluid models, that connect between the SSW sources in the corona and the heliosphere. Recently, hybrid models that combine fluid electrons and kinetic ions of the expanding solar wind were developed, and provide further insights of the local SSW plasma heating processes that related to turbulent magnetic fluctuations spectra and kinetic ion instabilities observed in the SSW plasma. These models produce the velocity distribution functions (VDFs) of the protons and heavier ions as well as the ion anisotropic temperatures. I will discuss the results of the above observations and models, and review the current status of our understanding of the fundamental physics of the SSW. I will review the open questions, and discuss how they could be addressed with near future observations and models. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663897-comparison-between-physics-based-polytropic-mhd-models-stellar-coronae-stellar-winds-solar-analogs','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663897-comparison-between-physics-based-polytropic-mhd-models-stellar-coronae-stellar-winds-solar-analogs">A Comparison between Physics-based and Polytropic MHD Models for Stellar Coronae and Stellar Winds of Solar Analogs</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Cohen, O. The development of the Zeeman–Doppler Imaging (ZDI) technique has provided synoptic observations of surface magnetic fields of low-mass stars. This led the stellar astrophysics community to adopt modeling techniques that have been used in solar physics using solar magnetograms. However, many of these techniques have been neglected by the solar community due to their failure to reproduce solar observations. Nevertheless, some of these techniques are still used to simulate the coronae and winds of solar analogs. Here we present a comparative study between two MHD models for the solar corona and solar wind. The first type of model is amore » polytropic wind model, and the second is the physics-based AWSOM model. We show that while the AWSOM model consistently reproduces many solar observations, the polytropic model fails to reproduce many of them, and in the cases where it does, its solutions are unphysical. Our recommendation is that polytropic models, which are used to estimate mass-loss rates and other parameters of solar analogs, must first be calibrated with solar observations. Alternatively, these models can be calibrated with models that capture more detailed physics of the solar corona (such as the AWSOM model) and that can reproduce solar observations in a consistent manner. Without such a calibration, the results of the polytropic models cannot be validated, but they can be wrongly used by others.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986GeoRL..13..411S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986GeoRL..13..411S">The interaction of heavy ions from Comet P/Giacobini-Zinner with the solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sanderson, T. R.; Wenzel, K.-P.; Daly, P.; Cowley, S. W. H.; Hynds, R. J.; Smith, E. J.; Bame, S. J.; Zwickl, R. D. 1986-04-01 The encounter between the ICE spacecraft and Comet P/Giacobini-Zinner was characterized in the solar wind by intense fluxes of heavy ions, measurable over a region 6 x 10 to the 6th km in extent. The ions are observed with highly anisotropic angular distributions, steep energy spectra, and a change in the energy spectrum at around 80 keV, consistent with a composition predominantly of the water group. Flux versus time profiles follow a general fall off with increasing distance from the comet, but with a marked inbound/outbound asymmetry. This asymmetry is due to the higher solar wind velocity on the outbound pass, giving rise to an increased energy gain of the pick-up ions. The flux versus time profiles are strongly modulated by the rapid changes in the direction of interplanetary magnetic field. Correlated observations of energetic ions, the interplanetary magnetic field and the solar wind are presented, and these observations are compared with theoretical predictions of the ion pick-up process. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987JGR....92...39C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987JGR....92...39C">Ion composition and upstream solar wind observations at comet Giacobini-Zinner</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Coplan, M. A.; Ogilvie, K. W.; A'Hearn, M. F.; Bochsler, P.; Geiss, J. 1987-01-01 The observations by the ion composition instrument (ICI) on the ICE spacecraft made during the encounter with comet P/Giacobini-Zinner (Ogilvie et al., 1986) are discussed in detail. Solar wind He-4(2+) kinetic temperatures, densities, and velocities before, during, and after the encounter are presented. These data combined with He-4(2+) velocity distributions provide evidence for the existence of a thick diffuse shock. Relative abundances of water group ions and CO(+) are derived along with an estimate of the abundance of an ion with M/Q = 24 + or - 1 amu/e. The ICI data are compared with electron data from two other experiments (Bame et al., 1986; Meyer-Vernet et al., 1986) and found to be in reasonable agreement in the region outside the tail. Spectroscopic data for several neutral and ionic species are compared with the ICI results for the water group ions and CO(+). The spectroscopic data are also used to eliminate Mg(+) and CN(+) as candidates for the M/Q = 24 peak. The two most likely candidates are C2(+) and Na(+), but neither photoionization of parent neutrals nor sputtering from dust grains is sufficient to explain the observed abundance relative to H2O(+). </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JGRA..110.1107G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JGRA..110.1107G">Direct evidence for magnetic reconnection in the solar wind near 1 AU</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gosling, J. T.; Skoug, R. M.; McComas, D. J.; Smith, C. W. 2005-01-01 We have obtained direct evidence for local magnetic reconnection in the solar wind using solar wind plasma and magnetic field data obtained by the Advanced Composition Explorer (ACE). The prime evidence consists of accelerated ion flow observed within magnetic field reversal regions in the solar wind. Here we report such observations obtained in the interior of an interplanetary coronal mass ejection (ICME) or at the interface between two ICMEs on 23 November 1997 at a time when the magnetic field was stronger than usual. The observed plasma acceleration was consistent with the Walen relationship, which relates changes in flow velocity to density-weighted changes in the magnetic field vector. Pairs of proton beams having comparable densities and counterstreaming relative to one another along the magnetic field at a speed of ˜1.4VA, where VA was the local Alfven speed, were observed near the center of the accelerated flow event. We infer from the observations that quasi-stationary reconnection occurred sunward of the spacecraft and that the accelerated flow occurred within a Petschek-type reconnection exhaust region bounded by Alfven waves and having a cross section width of ˜4 × 105 km as it swept over ACE. The counterstreaming ion beams resulted from solar wind plasma entering the exhaust region from opposite directions along the reconnected magnetic field lines. We have identified a limited number (five) of other accelerated flow events in the ACE data that are remarkably similar to the 23 November 1997 event. All such events identified occurred at thin current sheets associated with moderate to large changes in magnetic field orientation (98°-162°) in plasmas characterized by low proton beta (0.01-0.15) and high Alfven speed (51-204 km/s). They also were all associated with ICMEs. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active">20</li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active">21</li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667453-suprathermal-solar-wind-electrons-langmuir-turbulence','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667453-suprathermal-solar-wind-electrons-langmuir-turbulence">SUPRATHERMAL SOLAR WIND ELECTRONS AND LANGMUIR TURBULENCE</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kim, Sunjung; Yoon, Peter H.; Choe, G. S. 2016-09-01 The steady-state model recently put forth for the solar wind electron velocity distribution function during quiet time conditions, was originally composed of three population electrons (core, halo, and superhalo) with the core remaining nonresonant with any plasma waves while the halo and superhalo separately maintained steady-state resonance with whistler- and Langmuir-frequency range fluctuations, respectively. However, a recent paper demonstrates that whistler-range fluctuations in fact have no significant contribution. The present paper represents a consummation of the model in that a self-consistent model of the suprathermal electron population, which encompasses both the halo and the superhalo, is constructed solely on themore » basis of the Langmuir fluctuation spectrum. Numerical solutions to steady-state particle and wave kinetic equations are obtained on the basis of an initial trial electron distribution and Langmuir wave spectrum. Such a finding offers a self-consistent explanation for the observed steady-state electron distribution in the solar wind.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870062204&hterms=solar+pumping&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsolar%2Bpumping','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870062204&hterms=solar+pumping&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsolar%2Bpumping">Solar wind diagnostics from Doppler-enhanced scattering</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Noci, Giancarlo; Kohl, John L.; Withbroe, George L. 1987-01-01 Solar wind ions can attain sufficient outflow speed, w, to cause line excitation by chromospheric or transition region radiation in a nearby line. It is shown that this extends the diagnostic possibilities of a coronal EUV line to much larger values of w than would be possible if pumping were limited to radiation from the same spectral line. For the 1037.6 A coronal line of O VI, the pumping effect of the chromospheric C II 1037.0 A line is efficient for w between 100 and 250 km/s. An approximate expression for the line ratio for a doublet of the Li or Na isoelectronic sequences is derived, and the diagnostic capabilities of doublet line ratios, either by themselves or combined with the observation of other quantities, are discussed. In particular, that the determination of doublet line ratios at several heights can be sufficient to yield the solar wind velocity at those heights together with a constraint on other coronal parameters. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4508932','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4508932">Two-step forecast of geomagnetic storm using coronal mass ejection and solar wind condition</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Kim, R-S; Moon, Y-J; Gopalswamy, N; Park, Y-D; Kim, Y-H 2014-01-01 To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study (Bz ≤ −5 nT or Ey ≥ 3 mV/m for t≥ 2 h for moderate storms with minimum Dst less than −50 nT) and a Dst model developed by Temerin and Li (2002, 2006) (TL model). Using 55 CME-Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90%) than the forecasts based on the TL model (87%). However, the latter produces better forecasts for 24 nonstorm events (88%), while the former correctly forecasts only 71% of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80%) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (∩), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81%) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (∪), all geomagnetic storms are correctly forecasted. PMID:26213515 </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26213515','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26213515">Two-step forecast of geomagnetic storm using coronal mass ejection and solar wind condition.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Kim, R-S; Moon, Y-J; Gopalswamy, N; Park, Y-D; Kim, Y-H 2014-04-01 To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study ( B z ≤ -5 nT or E y ≥ 3 mV/m for t ≥ 2 h for moderate storms with minimum Dst less than -50 nT) and a Dst model developed by Temerin and Li (2002, 2006) (TL model). Using 55 CME- Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90%) than the forecasts based on the TL model (87%). However, the latter produces better forecasts for 24 nonstorm events (88%), while the former correctly forecasts only 71% of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80%) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (∩), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81%) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (∪), all geomagnetic storms are correctly forecasted. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021278&hterms=atom+composition&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Datom%2Bcomposition','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021278&hterms=atom+composition&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Datom%2Bcomposition">Solar wind ion composition and charge states</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> vonSteiger, R. 1995-01-01 The solar wind, a highly tenuous plasma streaming from the Sun into interplanetary space at supersonic speed, is roughly composed of 95% hydrogen and 5% helium by number. All other, heavy elements contribute less than 0.1% by number and thus are truly test particles Nevertheless, these particles provide valuable information not present in the main components. We first discuss the importance of the heavy ions as tracers for processes in the solar atmosphere. Specifically, their relative abundances are found to be different in the solar wind as compared to the photosphere. This fractionation, which is best organized as a function of the first ionization time (FIT) of the elements under solar surface conditions, provides information on the structure of the chromosphere. where it is imparted on the partially ionized material by an atom-ion separation mechanism. Moreover, the charge states of the heavy ions can be used to infer the coronal temperature, since they are frozen-in near the altitude where the expansion time scale overcomes the ionization/recombination time scales. Next, we review the published values of ion abundances in the solar wind, concentrating on the recent results of the SWICS instrument on Ulysses. About 8 elements and more than 20 charge states can be routinely analyzed by this sensor. There is clear evidence that both the composition and the charge state distribution is significantly different in the fast solar wind from the south polar coronal hole, traversed by Ulysses in 1993/94, as compared to the solar wind normally encountered near the ecliptic plane. The fractionation between low- and high-FIT elements is reduced, and the charge states indicate a lower, more uniform coronal temperature in the hole. Finally, we discuss these results in the framework of existing theoretical models of the chromosphere and corona, attempting to identify differences between the low- and high-latitude regions of the solar atmosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH13D..06R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH13D..06R">Observations of thermal and suprathermal tail ions from WIND</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Randol, B. M.; Christian, E. R.; Wilson, L. B., III 2016-12-01 The velocity distribution function (VDF) of solar wind protons (as well as other ion populations) is comprised of a thermal Maxwellian core and an accelerated suprathermal tail, beginning at around 1 keV in the frame co-moving with solar wind bulk velocity. The form of the suprathermal tail is a power law in phase space density, f, vs. speed, v, such that f / vγ, where γ is the power law index. This commonly observed index is of particular interest because no traditional theory predicts its existence. We need more data in order to test these theories. The general shape is of interest because it is kappa-like. We show combined observations from three different instruments on the WIND spacecraft: 3DP/PLSP, STICS, and 3DP/SST/Open. These data stretch from 102 to 107 eV in energy, encompassing both the thermal and suprathermal proton populations. We show further evidence for this kappa-like distribution and report on our progress on fitting of empirical functions to these data. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.2191W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2191W">Quiet-Time Suprathermal (˜0.1 - 200 keV) Electrons in the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wang, Linghua; Yang, Liu; Tao, Jiawei; Zong, Qiugang; Li, Gang; Wimmer-Schweingruber, Robert; He, Jiansen; Tu, Chuanyi; Bale, Stuart 2017-04-01 We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-200 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. The observed energy spectrum of both (beaming) strahl and (isotropic) halo electrons at ˜0.1-1.5 keV generally fits to a Kappa distribution function with an index κ and effective temperature Teff, while the observed energy spectrum of nearly isotropic superhalo electrons at ˜20-200 keV generally fits to a power-law function, J ˜ E-β. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl density and halo density. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. For the superhalo population, the spectral index β ranges from ˜1.6 to ˜3.7 and the integrated density nsup ranges from 10-8 cm-3 to 10-5 cm-3, with no clear association with the sunspot number. In solar cycle 23 (24), the distribution of β has a broad maximum between 2.4 and 2.8 (2.0 and 2.4). All the strahl, halo and superhalo populations show no obvious correlation with the solar wind core population. These results reflect the nature of the generation of solar wind suprathermal electrons. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663851-model-dissipation-solar-wind-magnetic-turbulence-kinetic-alfven-waves-electron-scales-comparison-observations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663851-model-dissipation-solar-wind-magnetic-turbulence-kinetic-alfven-waves-electron-scales-comparison-observations">A Model for Dissipation of Solar Wind Magnetic Turbulence by Kinetic Alfvén Waves at Electron Scales: Comparison with Observations</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Schreiner, Anne; Saur, Joachim, E-mail: schreiner@geo.uni-koeln.de In hydrodynamic turbulence, it is well established that the length of the dissipation scale depends on the energy cascade rate, i.e., the larger the energy input rate per unit mass, the more the turbulent fluctuations need to be driven to increasingly smaller scales to dissipate the larger energy flux. Observations of magnetic spectral energy densities indicate that this intuitive picture is not valid in solar wind turbulence. Dissipation seems to set in at the same length scale for different solar wind conditions independently of the energy flux. To investigate this difference in more detail, we present an analytic dissipation modelmore » for solar wind turbulence at electron scales, which we compare with observed spectral densities. Our model combines the energy transport from large to small scales and collisionless damping, which removes energy from the magnetic fluctuations in the kinetic regime. We assume wave–particle interactions of kinetic Alfvén waves (KAWs) to be the main damping process. Wave frequencies and damping rates of KAWs are obtained from the hot plasma dispersion relation. Our model assumes a critically balanced turbulence, where larger energy cascade rates excite larger parallel wavenumbers for a certain perpendicular wavenumber. If the dissipation is additionally wave driven such that the dissipation rate is proportional to the parallel wavenumber—as with KAWs—then an increase of the energy cascade rate is counterbalanced by an increased dissipation rate for the same perpendicular wavenumber, leading to a dissipation length independent of the energy cascade rate.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950032354&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950032354&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dsolar%2Bintensity%2Bmeasurement">Latitudinal variation of speed and mass flux in the acceleration region of the solar wind inferred from spectral broadening measurements</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Woo, Richard; Goldstein, Richard M. 1994-01-01 Spectral broadening measurements conducted at S-band (13-cm wavelength) during solar minimum conditions in the heliocentric distance range of 3-8 R(sub O) by Mariner 4, Pioneer 10, Mariner 10, Helios 1, Helios 2, and Viking have been combined to reveal a factor of 2.6 reduction in bandwidth from equator to pole. Since spectral broadening bandwidth depends on electron density fluctuation and solar wind speed, and latitudinal variation of the former is available from coherence bandwidth measurements, the remote sensing spectral broadening measurements provide the first determination of the latitudinal variation of solar wind speed in the acceleration region. When combined with electron density measurements deduced from white-light coronagraphs, this result also leads to the first determination of the latitudinal variation of mass flux in the acceleration region. From equator to pole, solar wind speed increases by a factor of 2.2, while mass flux decreases by a factor of 2.3. These results are consistent with measurements of solar wind speed by multi-station intensity scintillation measurements, as well as measurements of mass flux inferred from Lyman alpha observations, both of which pertain to the solar wind beyond 0.5 AU. The spectral broadening observations, therefore, strengthen earlier conclusions about the latitudinal variation of solar wind speed and mass flux, and reinforce current solar coronal models and their implications for solar wind acceleration and solar wind modeling. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH51D2534R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH51D2534R">Determining the Dimensions of the Heliosphere from the Time-Correlation of IBEX ENA Observations with Variations in the Solar Wind Dynamic Pressure</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Reisenfeld, D. B.; Bzowski, M.; Funsten, H. O.; Janzen, P. H.; Kubiak, M. A.; McComas, D. J.; Schwadron, N.; Sokol, J. M. 2017-12-01 The IBEX mission has shown that variations in the ENA flux from the outer heliosphere are associated with the solar cycle. In particular, there is a good correlation between the dynamic pressure of the outbound solar wind and variations in the observed IBEX ENA flux (McComas et al, 2017; Reisenfeld et al., 2016). There is, of course, a time difference between observations of the outbound SW and the heliospheric ENAs with which they correlate, ranging from approximately two to four years, depending on ENA energy and look direction. In this study, we use this time difference as a means of "sounding" the heliosheath, that is, finding the average distance to the ENA source region in a particular direction. We use data from the first seven years of the IBEX mission. As each point in the sky is sampled once every six months, this gives us a time series of 14 points per look direction on which to time correlate. Fluxes are transformed from the spacecraft frame into a heliospheric inertial frame to remove the effects of spacecraft/Earth motion. Fluxes are also corrected for ENA extinction due to charge exchange. To improve statistics, we divide the sky into "macropixels" spanning 30 degrees in longitude and varying ranges of latitude to maintain comparable counting statistics per pixel. In calculating the response time, we account for the varying speed of the outbound solar wind by using a time and latitude dependent set of solar wind speeds derived from interplanetary scintillation data (Sokol et al. 2015). Consistent with heliospheric models, we determine the shortest distance to the heliopause is in the nose direction, with a flaring toward the flanks and poles. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770059881&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D80%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770059881&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D80%26Ntt%3Dlazarus">A comparison of solar wind streams and coronal structure near solar minimum</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Nolte, J. T.; Davis, J. M.; Gerassimenko, M.; Lazarus, A. J.; Sullivan, J. D. 1977-01-01 Solar wind data from the MIT detectors on the IMP 7 and 8 satellites and the SOLRAD 11B satellite for the solar-minimum period September-December, 1976, were compared with X-ray images of the solar corona taken by rocket-borne telescopes on September 16 and November 17, 1976. There was no compelling evidence that a coronal hole was the source of any high speed stream. Thus it is possible that either coronal holes were not the sources of all recurrent high-speed solar wind streams during the declining phase of the solar cycle, as might be inferred from the Skylab period, or there was a change in the appearance of some magnetic field regions near the time of solar minimum. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663176-imprint-suns-evolving-polar-winds-ibex-energetic-neutral-atom-all-sky-observations-heliosphere','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663176-imprint-suns-evolving-polar-winds-ibex-energetic-neutral-atom-all-sky-observations-heliosphere">Imprint of the Sun’s Evolving Polar Winds on IBEX Energetic Neutral Atom All-sky Observations of the Heliosphere</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Zirnstein, E. J.; McComas, D. J.; Dayeh, M. A. 2017-09-01 With 7 years of Interstellar Boundary Explorer ( IBEX ) measurements of energetic neutral atoms (ENAs), IBEX has shown a clear correlation between dynamic changes in the solar wind and the heliosphere’s response in the formation of ENAs. In this paper, we investigate temporal variations in the latitudinal-dependent ENA spectrum from IBEX and their relationship to the solar wind speed observed at 1 au. We find that the variation in latitude of the transition in ENA spectral indices between low (≲1.8) and high (≳1.8) values, as well as the distribution of ENA spectral indices at high and low latitudes, correlatesmore » well with the evolution of the fast and slow solar wind latitudinal structure observed near 1 au. This correlation includes a delay due to the time it takes the solar wind to propagate to the termination shock and into the inner heliosheath, and for ENAs to be generated via charge-exchange and travel back toward 1 au. Moreover, we observe a temporal asymmetry in the steepening of the ENA spectrum in the northern and southern hemispheres, consistent with asymmetries observed in the solar wind and polar coronal holes. While this asymmetry is observed near the upwind direction of the heliosphere, it is not yet observed in the tail direction, suggesting a longer line-of-sight integration distance or different processing of the solar wind plasma downstream of the termination shock.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010016289&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010016289&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsolar%2Bintensity%2Bmeasurement">MACS, An Instrument, and a Methodology for Simulations and Global Measurements of the Coronal Electron Temperature and the Solar Wind Velocity on the Solar Corona</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Reginald, Nelson L.; Fisher, Richard R. (Technical Monitor) 2000-01-01 The determination of the radial and latitudinal temperature and wind profiles of the solar corona is of great importance in understanding the coronal heating mechanism and the dynamics of coronal expansion. Cram presented the theory for the formation of the K-coronal spectrum and identified two important observations. He observed the existence of temperature sensitive anti-nodes at certain wavelengths in the theoretical K-coronal spectra. The anti-nodes are separated by temperature-insensitive nodes. Remarkably, Cram showed that the wavelengths of the nodes and anti-nodes are almost independent of altitude above the solar limb. Because of these features, Cram suggested that the intensity ratios at two anti-nodes could be used as a diagnostic of the electron temperature in the K-corona. Based on this temperature diagnostic technique prescribed by Cram a slit-based spectroscopic study was performed by Ichimoto et al. on the solar corona in conjunction with the total solar eclipse of 3 Nov 1994 in Putre, Chile to determine the temperature profile of the solar corona. In this thesis Cram's theory has been extended to incorporate the role of the solar wind in the formation of the K-corona, and we have identified both temperature and wind sensitive intensity ratios. The instrument, MACS, for Multi Aperture Coronal Spectrometer, a fiber optic based spectrograph, was designed for global and simultaneous measurement of the thermal electron temperature and the solar wind velocity in the solar corona. The first ever experiment of this nature was conducted in conjunction with the total solar eclipse of 11 Aug 1999 in Elazig, Turkey. In this instrument one end of each of twenty fiber optic tips were positioned in the focal plane of the telescope in such a way that we could observe conditions simultaneously at many different latitudes and two different radial distances in the solar corona. The other ends of the fibers were vertically aligned and placed at the primary focus of </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SSRv..200..495M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SSRv..200..495M">The MAVEN Solar Wind Electron Analyzer</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mitchell, D. L.; Mazelle, C.; Sauvaud, J.-A.; Thocaven, J.-J.; Rouzaud, J.; Fedorov, A.; Rouger, P.; Toublanc, D.; Taylor, E.; Gordon, D.; Robinson, M.; Heavner, S.; Turin, P.; Diaz-Aguado, M.; Curtis, D. W.; Lin, R. P.; Jakosky, B. M. 2016-04-01 The MAVEN Solar Wind Electron Analyzer (SWEA) is a symmetric hemispheric electrostatic analyzer with deflectors that is designed to measure the energy and angular distributions of 3-4600-eV electrons in the Mars environment. This energy range is important for impact ionization of planetary atmospheric species, and encompasses the solar wind core and halo populations, shock-energized electrons, auroral electrons, and ionospheric primary photoelectrons. The instrument is mounted at the end of a 1.5-meter boom to provide a clear field of view that spans nearly 80 % of the sky with ˜20° resolution. With an energy resolution of 17 % (Δ E/E), SWEA readily distinguishes electrons of solar wind and ionospheric origin. Combined with a 2-second measurement cadence and on-board real-time pitch angle mapping, SWEA determines magnetic topology with high (˜8-km) spatial resolution, so that local measurements of the plasma and magnetic field can be placed into global context. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840024844','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840024844">Wind loading on solar concentrators: Some general considerations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Roschke, E. J. 1984-01-01 A survey was completed to examine the problems and complications arising from wind loading on solar concentrators. Wind loading is site specific and has an important bearing on the design, cost, performance, operation and maintenance, safety, survival, and replacement of solar collecting systems. Emphasis herein is on paraboloidal, two-axis tracking systems. Thermal receiver problems also are discussed. Wind characteristics are discussed from a general point of view. Current methods for determining design wind speed are reviewed. Aerodynamic coefficients are defined and illustrative examples are presented. Wind tunnel testing is discussed, and environmental wind tunnels are reviewed. Recent results on heliostat arrays are reviewed as well. Aeroelasticity in relation to structural design is discussed briefly. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000023157','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000023157">An Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Riley, Peter 2000-01-01 This investigation is concerned with the large-scale evolution and topology of coronal mass ejections (CMEs) in the solar wind. During this reporting period we have focused on several aspects of CME properties, their identification and their evolution in the solar wind. The work included both analysis of Ulysses and ACE observations as well as fluid and magnetohydrodynamic simulations. In addition, we analyzed a series of "density holes" observed in the solar wind, that bear many similarities with CMEs. Finally, this work was communicated to the scientific community at three meetings and has led to three scientific papers that are in various stages of review. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NIMPB.408..114N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NIMPB.408..114N">Solar wind charge exchange in laboratory - Observation of forbidden X-ray transitions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Numadate, Naoki; Shimaya, Hirofumi; Ishida, Takuya; Okada, Kunihiro; Nakamura, Nobuyuki; Tanuma, Hajime 2017-10-01 We have reproduced solar wind charge exchange collisions of hydrogen-like O7+ ions with He gas at collision energies of 42 keV in the laboratory and observed the forbidden transition of 1s21S0 -1s2s 3S1 in helium-like O6+ ions produced by single electron capture. The measured soft X-ray spectrum had a peak at 560 eV which corresponds to the energy of the forbidden 1s21S0 -1s2s 3S1 transition in the O6+ ion, and a reasonable energy difference between peak positions of the forbidden and resonance lines was found, which ensured that we succeeded in observing the forbidden transition of O6+ ions. The dominant electron capture level in the collision of O7+ ions with He can be estimated to be a principal quantum number n = 4 by the classical over barrier model and the two-center atomic orbital close coupling method. After the charge exchange, the population of the 1s2s state becomes large due to cascade transitions from the higher excited states, so the long-lived forbidden transition to the 1s21S0 ground state is one of main features observed in the charge exchange spectra. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021410&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dbackground%2Bwind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021410&hterms=background+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dbackground%2Bwind">Propagation of large amplitude Alfven waves in the solar wind neutral sheet</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Malara, F.; Primavera, L.; Veltri, P. 1995-01-01 Analysis of solar wind fluctuation data show that the correlation between velocity and magnetic field fluctuations decreases when going farther away from the Sun. This decorrelation can be attributed either to the time evolution of the fluctuations, carried away by the solar wind, or to the interaction between the solar wind neutral sheet and Alfven waves. To check this second hypothesis we have numerically studied the propagation of Alfven waves in the solar wind neutral sheet. The initial conditions have been set up in order to guarantee B(exp 2) = const, so that the following numerical evolution is only due to the inhomogeneity in the background magnetic field. The analysis of the results shows that compressive structures are formed, mainly in the neutral sheet where they have been identified as pressure balanced structures, i.e., tangential discontinuities. Fast perturbations, which are also produced, have a tendency to leave the simulation domain, propagating also perpendicularly to the mean magnetic field. For this reason the level of fast perturbations is always smaller with respect to the previously cited plasma balanced structures, which are slow mode perturbations. A comparison between the numerical results and some particular observational issues is also presented. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27367391','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27367391">Ensemble Space-Time Correlation of Plasma Turbulence in the Solar Wind.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Matthaeus, W H; Weygand, J M; Dasso, S 2016-06-17 Single point measurement turbulence cannot distinguish variations in space and time. We employ an ensemble of one- and two-point measurements in the solar wind to estimate the space-time correlation function in the comoving plasma frame. The method is illustrated using near Earth spacecraft observations, employing ACE, Geotail, IMP-8, and Wind data sets. New results include an evaluation of both correlation time and correlation length from a single method, and a new assessment of the accuracy of the familiar frozen-in flow approximation. This novel view of the space-time structure of turbulence may prove essential in exploratory space missions such as Solar Probe Plus and Solar Orbiter for which the frozen-in flow hypothesis may not be a useful approximation. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930049573&hterms=solar+two&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsolar%2Btwo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930049573&hterms=solar+two&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsolar%2Btwo">A two-fluid model of the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sandbaek, O.; Leer, E.; Holzer, T. E. 1992-01-01 A method is presented for the integration of the two-fluid solar-wind equations which is applicable to a wide variety of coronal base densities and temperatures. The method involves proton heat conduction, and may be applied to coronal base conditions for which subsonic-supersonic solar wind solutions exist. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active">21</li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active">22</li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMSH33A0369A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMSH33A0369A">Genesis Solar Wind Array Collector Fragments Post-Recovery Status</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Allton, J. H. 2005-12-01 The Genesis solar wind sample return mission spacecraft was launched with 271 whole and 30 half hexagonally-shaped collectors. At 65 cm2 per hexagon, the total collection area was 18,600 cm2. These 301 collectors were comprised of 9 materials mounted on 5 arrays, each of which was exposed to a specific regime of the solar wind. Thoughtfully, collectors exposed to a specific regime were made of a unique thickness: bulk solar wind (700 μm thick), transient solar wind associated with coronal mass ejection (650 μm), high speed solar wind from coronal holes (600 μm), and interstream low-speed solar wind (550 μm). Thus, it is easy to distinguish the solar wind regime sampled by measuring the fragment thickness. Nearly 10,000 fragments have been enumerated, constituting about 20% of the total area. The sapphire-based hexagons survived better than the silicon hexagons as seen in the percent pre-flight whole collectors compared to the percent of recovered fragments in 10 to 25 mm size range. Silicon-based collectors accounted for 57% of the hexagons flown but 18% of the recovered fragments. However, a) gold coating on sapphire accounted for 12% flown and 27% of the recovered; b) aluminum coating on sapphire for 9% flown and 25% of the recovered; c) silicon coating on sapphire for 7% flown and 18% of the recovered; and d) sapphire for 7% flown and 10% of the recovered. Due to the design of the array frames, many of the recovered fragments were trapped in baffles very near their original location and were relatively protected from outside debris. Collector fragments are coated with particulate debris, and there is evidence that a thin molecular film was deposited on collector surfaces during flight. Therefore, in addition to allocations distributed for solar wind science analysis, poorer quality samples have been used in specimen cleaning tests. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780061297&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D70%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780061297&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D70%26Ntt%3Dlazarus">Comparison of 74-MHz interplanetary scintillation and IMP 7 observations of the solar wind during 1973</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Coles, W. A.; Harmon, J. K.; Lazarus, A. J.; Sullivan, J. D. 1978-01-01 Solar wind velocities measured by earth-orbiting spacecraft are compared with velocities determined from interplanetary scintillation (IPS) observations for 1973, a period when high-velocity streams were prevalent. The spacecraft and IPS velocities agree well in the mean and are highly correlated. No simple model for the distribution of enhanced turbulence within streams is sufficient to explain the velocity comparison results for the entire year. Although a simple proportionality between density fluctuation level and bulk density is consistent with IPS velocities for some periods, some streams appear to have enhanced turbulence in the high-velocity region, where the density is low. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Solar+AND+system&id=EJ876099','ERIC'); return false;" href="https://eric.ed.gov/?q=Solar+AND+system&id=EJ876099">Wind in the Solar System</a> <a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a> McIntosh, Gordon 2010-01-01 As an astronomy instructor I am always looking for commonly experienced Earthly phenomena to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote short "TPT" articles on frost and precipitation. The present article is on winds in the solar system. A windy day or storm might… </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.6899D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6899D">Study of solar wind spectra by nonlinear waves interaction</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dwivedi, Navin; Sharma, Rampal; Narita, Yasuhito 2014-05-01 The nature of small-scale turbulent fluctuations in the solar wind (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 solar wind 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 solar wind turbulence and particles acceleration. This work is partially supported by DST (India) and FP7/STORM (313038) </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.474..115H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.474..115H">Kinetic Theory and Fast Wind Observations of the Electron Strahl</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Horaites, Konstantinos; Boldyrev, Stanislav; Wilson, Lynn B., III; Viñas, Adolfo F.; Merka, Jan 2018-02-01 We develop a model for the strahl population in the solar wind - a narrow, low-density and high-energy electron beam centred on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances where the plasma density, temperature and the magnetic field strength decline as power laws of the distance along a magnetic flux tube. Our solution for the strahl depends on a number of parameters that, in the absence of the analytic solution for the full electron velocity distribution function (eVDF), cannot be derived from the theory. We however demonstrate that these parameters can be efficiently found from matching our solution with observations of the eVDF made by the Wind satellite's SWE strahl detector. The model is successful at predicting the angular width (FWHM) of the strahl for the Wind data at 1 au, in particular by predicting how this width scales with particle energy and background density. We find that the strahl distribution is largely determined by the local temperature Knudsen number γ ∼ |T dT/dx|/n, which parametrizes solar wind collisionality. We compute averaged strahl distributions for typical Knudsen numbers observed in the solar wind, and fit our model to these data. The model can be matched quite closely to the eVDFs at 1 au; however, it then overestimates the strahl amplitude at larger heliocentric distances. This indicates that our model may be improved through the inclusion of additional physics, possibly through the introduction of 'anomalous diffusion' of the strahl electrons. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JGRA..107.1383V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JGRA..107.1383V">Long-term-average, solar cycle, and seasonal response of magnetospheric energetic electrons to the solar wind speed</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Vassiliadis, D.; Klimas, A. J.; Kanekal, S. G.; Baker, D. N.; Weigel, R. S. 2002-11-01 Among the interplanetary activity parameters the solar wind speed is the one best correlated with the energetic electron fluxes in the inner magnetosphere. We examine the radial and temporal characteristics of the 2-6 MeV electron response, approximating it in this paper with linear filters. The filter response is parameterized by the time delay (τ), measured from the time of solar wind impact, and the L shell (L). We examine solar cycle and seasonal effects using an 8-year-long database of Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX)/ Proton Electron Telescope (PET) measurements at the radial range L = 1.1-10. The main peak P1 of the long-term-average response is at (τ, L) = (2, 5.3) and has a simultaneous response over a wide range of radial distances, ΔL = 5. The duration of the response after the peak is inversely proportional to the L shell. The central part of the inner magnetosphere (L = 3.7-5.75) has a much more prolonged response (>10 days) than other parts. Prior to the main response, P1, a brief response, P0, of typically lower amplitude appears at (τ, L) = (0, 3), probably as a quasi-adiabatic response to the compression of the magnetosphere by the solar wind pressure. Over the solar cycle the variation in solar wind input results in a systematic change of the position, amplitude, radial extent, and duration of the two peaks: during solar wind minimum the quasi-adiabatic peak disappears, and the radial size of the responding region decreases; both are responses to low-density, high-speed streams. During solar minimum, the duration is at least 3 days (30%) longer than average, probably due to the sustained solar wind input. Systematic variations appear also as a function of season due to several magnetic and fluid effects. During equinoxes the coupling is stronger, and the duration is longer (by at least 2 days) compared to solstices. Between the two equinoxes the fall response has a significantly higher amplitude and longer </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSH43F..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSH43F..01C">Telescoping in on the Microscopic Origins of the Fast Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cranmer, S. R. 2011-12-01 Despite many years of study, the basic physical processes that are responsible for producing the solar wind are not known (or at least not universally agreed upon). The fact that we have an overabundance of proposed ideas for solving the problems of coronal heating and wind acceleration can be seen as both a blessing and a curse. It is a blessing because it highlights the insight and creativity of the community, but it is a curse because we still do not know how to validate or falsify many of these ideas. Discerning the presence of any given proposed mechanism is difficult not only because measurements are limited, but also because many of the suggested processes act on a wide range of spatial scales (from centimeters to solar radii) with complex feedback effects that are not yet understood. This presentation will discuss a few key examples and controversies regarding the importance of small spatial and temporal scales in the regions where the solar wind is accelerated. For example, new observations have led to a revived debate about whether the hot plasma in the solar wind is injected dynamically from cooler regions below or whether it "evaporates" from the combined effects of radiation and conduction from above. There is also debate about how the open field lines are energized: Is the energy input from waves and turbulent eddies that propagate up from the Sun and dissipate, or is the constantly evolving magnetic carpet responsible for heating the plasma via reconnection? In some areas, traditional observational diagnostics of magnetohydrodynamic plasma properties may not be sufficient to distinguish between competing predictions. Thus, this presentation will also describe why it is probably wise to confront the truly microscopic (nonlinear, non-Maxwellian, collisionless) nature of the relevant particles and fields. Theories and measurements that "zoom in" to this level of kinetic detail have the greatest potential for improving our understanding of the origins of </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017HGSS....8...21S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017HGSS....8...21S">Origin of the Wang-Sheeley-Arge solar wind model</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sheeley, Neil R., Jr. 2017-03-01 A correlation between solar wind speed at Earth and the amount of magnetic field line expansion in the corona was verified in 1989 using 22 years of solar and interplanetary observations. We trace the evolution of this relationship from its birth 15 years earlier in the Skylab era to its current use as a space weather forecasting technique. This paper is the transcript of an invited talk at the joint session of the Historical Astronomy Division and the Solar Physics Division of the American Astronomical Society during its 224th meeting in Boston, MA, on 3 June 2014. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060041403&hterms=imprint&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dimprint','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060041403&hterms=imprint&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dimprint">Imprint of the Sun on the Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Woo, R.; Habbal, S. R. 1998-01-01 Observations of the inner corona in polarized brightness by the Mauna Loa MkIII K-coronameter and soft X-ray by Yohkoh of the inner corona are combined with Ulysses radio occultation measurements of the solar wind to demonstrate that the signature of active regions and bright points is present in the heliocentric distance range of 10-30 Ro. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH33B2770B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH33B2770B">Anisotropic Behaviour of Magnetic Power Spectra in Solar Wind Turbulence.</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Banerjee, S.; Saur, J.; Gerick, F.; von Papen, M. 2017-12-01 Introduction:High altitude fast solar wind turbulence (SWT) shows different spectral properties as a function of the angle between the flow direction and the scale dependent mean magnetic field (Horbury et al., PRL, 2008). The average magnetic power contained in the near perpendicular direction (80º-90º) was found to be approximately 5 times larger than the average power in the parallel direction (0º- 10º). In addition, the parallel power spectra was found to give a steeper (-2) power law than the perpendicular power spectral density (PSD) which followed a near Kolmogorov slope (-5/3). Similar anisotropic behaviour has also been observed (Chen et al., MNRAS, 2011) for slow solar wind (SSW), but using a different method exploiting multi-spacecraft data of Cluster. Purpose:In the current study, using Ulysses data, we investigate (i) the anisotropic behaviour of near ecliptic slow solar wind using the same methodology (described below) as that of Horbury et al. (2008) and (ii) the dependence of the anisotropic behaviour of SWT as a function of the heliospheric latitude.Method:We apply the wavelet method to calculate the turbulent power spectra of the magnetic field fluctuations parallel and perpendicular to the local mean magnetic field (LMF). According to Horbury et al., LMF for a given scale (or size) is obtained using an envelope of the envelope of that size. Results:(i) SSW intervals always show near -5/3 perpendicular spectra. Unlike the fast solar wind (FSW) intervals, for SSW, we often find intervals where power parallel to the mean field is not observed. For a few intervals with sufficient power in parallel direction, slow wind turbulence also exhibit -2 parallel spectra similar to FSW.(ii) The behaviours of parallel and perpendicular power spectra are found to be independent of the heliospheric latitude. Conclusion:In the current study we do not find significant influence of the heliospheric latitude on the spectral slopes of parallel and perpendicular </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...793..118D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...793..118D">Evolution of Turbulence in the Expanding Solar Wind, a Numerical Study</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dong, Yue; Verdini, Andrea; Grappin, Roland 2014-10-01 We study the evolution of turbulence in the solar wind by solving numerically the full three-dimensional (3D) magnetohydrodynamic (MHD) equations embedded in a radial mean wind. The corresponding equations (expanding box model or EBM) have been considered earlier but never integrated in 3D simulations. Here, we follow the development of turbulence from 0.2 AU up to about 1.5 AU. Starting with isotropic spectra scaling as k -1, we observe a steepening toward a k -5/3 scaling in the middle of the wave number range and formation of spectral anisotropies. The advection of a plasma volume by the expanding solar wind causes a non-trivial stretching of the volume in directions transverse to radial and the selective decay of the components of velocity and magnetic fluctuations. These two effects combine to yield the following results. (1) Spectral anisotropy: gyrotropy is broken, and the radial wave vectors have most of the power. (2) Coherent structures: radial streams emerge that resemble the observed microjets. (3) Energy spectra per component: they show an ordering in good agreement with the one observed in the solar wind at 1 AU. The latter point includes a global dominance of the magnetic energy over kinetic energy in the inertial and f -1 range and a dominance of the perpendicular-to-the-radial components over the radial components in the inertial range. We conclude that many of the above properties are the result of evolution during transport in the heliosphere, and not just the remnant of the initial turbulence close to the Sun. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950037083&hterms=mass+fraction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmass%2Bfraction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950037083&hterms=mass+fraction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmass%2Bfraction">The solar cycle variation of coronal mass ejections and the solar wind mass flux</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Webb, David F.; Howard, Russell A. 1994-01-01 Coronal mass ejections (CMEs) are an important aspect of coronal physics and a potentially significant contributor to perturbations of the solar wind, such as its mass flux. Sufficient data on CMEs are now available to permit study of their longer-term occurrency patterns. Here we present the results of a study of CME occurrence rates over more than a complete 11-year solar sunspot cycle and a comparison of these rates with those of other activity related to CMEs and with the solar wind particle flux at 1 AU. The study includes an evaluation of correlations to the CME rates, which include instrument duty cycles, visibility functions, mass detection thresholds, and geometrical considerations. The main results are as follows: (1) The frequency of occurrence of CMEs tends to track the solar activity cycle in both amplitude and phase; (2) the CME rates from different instruments, when corrected for both duty cycles and visibility functions, are reasonably consistent; (3) considering only longer-term averages, no one class of solar activity is better correlated with CME rate than any other; (4) the ratio of the annualized CME to solar wind mass flux tends to track the solar cycle; and (5) near solar maximum, CMEs can provide a significant fraction (i.e., approximately equals 15%) of the average mass flux to the near-ecliptic solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017RvMPP...1....4Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017RvMPP...1....4Y">Kinetic instabilities in the solar wind driven by temperature anisotropies</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Yoon, Peter H. 2017-12-01 The present paper comprises a review of kinetic instabilities that may be operative in the solar wind, and how they influence the dynamics thereof. The review is limited to collective plasma instabilities driven by the temperature anisotropies. To limit the scope even further, the discussion is restricted to the temperature anisotropy-driven instabilities within the model of bi-Maxwellian plasma velocity distribution function. The effects of multiple particle species or the influence of field-aligned drift will not be included. The field-aligned drift or beam is particularly prominent for the solar wind electrons, and thus ignoring its effect leaves out a vast portion of important physics. Nevertheless, for the sake of limiting the scope, this effect will not be discussed. The exposition is within the context of linear and quasilinear Vlasov kinetic theories. The discussion does not cover either computer simulations or data analyses of observations, in any systematic manner, although references will be made to published works pertaining to these methods. The scientific rationale for the present analysis is that the anisotropic temperatures associated with charged particles are pervasively detected in the solar wind, and it is one of the key contemporary scientific research topics to correctly characterize how such anisotropies are generated, maintained, and regulated in the solar wind. The present article aims to provide an up-to-date theoretical development on this research topic, largely based on the author's own work. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TESS....131004A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TESS....131004A">Global MHD modeling of an ICME focused on the physics involved in an ICME interacting with a solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> An, Jun-Mo; Magara, Tetsuya; Inoue, Satoshi; Hayashi, Keiji; Tanaka, Takashi 2015-04-01 We developed a three-dimensional (3D) magnetohydrodynamic (MHD) code to investigate the structure of a solar wind, the properties of a coronal mass ejection (CME) and the interaction between them. This MHD code is based on the finite volume method incorporating total variation diminishing (TVD) scheme with an unstructured grid system. In particular, this grid system can avoid the singularity at the north and south poles and relax tight CFL conditions around the poles, both of which would arise in a spherical coordinate system (Tanaka 1994). In this model, we first apply an MHD tomographic method (Hayashi et al. 2003) to interplanetary scintillation (IPS) observational data and derive a solar wind from the physical values obtained at 50 solar radii away from the Sun. By comparing the properties of this solar wind to observational data obtained near the Earth orbit, we confirmed that our model captures the velocity, temperature and density profiles of a solar wind near the Earth orbit. We then insert a spheromak-type CME (Kataoka et al. 2009) into the solar wind to reproduce an actual CME event occurred on 29 September 2013. This has been done by introducing a time-dependent boundary condition to the inner boundary of our simulation domain (50rs < r < 300rs). On the basis of a comparison between the properties of a simulated CME and observations near the Earth, we discuss the physics involved in an ICME interacting with a solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995sowi.confS..75C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995sowi.confS..75C">Measurements of electric fields in the solar wind: Interpretation difficulties</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chertkov, A. D. 1995-06-01 The traditionally measured electric fields in the solar wind plasma (about 1-10 mV/m) are not the natural, primordial ones but are the result of plasma-vehicle interaction. The theory of this interaction is not complete now and current interpretation of the measurements can fail. The state of fully ionized plasma depends on the entropy of the creating source and on the process in which plasma is involved. The increasing twofold of a moving volume in the solar wind (with energy transfer across its surface which is comparable with its whole internal energy) is a more rapid process than the relaxation for the pressure. The presumptive source of the solar wind creation - the induction electric field of the solar origin - has very low entropy. The state of plasma must be very far from the state of thermodynamic equilibrium. The internal energy of plasma can be contained mainly in plasma waves, resonant plasma oscillations, and electric currents. The primordial microscopic oscillating electric fields could be about 1 V/m. It can be checked by special measurements, not ruining the natural plasma state. The tool should be a dielectrical microelectroscope outside the distortion zone of the spacecraft, having been observed from the latter. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021400&hterms=energy+Solar+vehicles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Denergy%2BSolar%2Bvehicles','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021400&hterms=energy+Solar+vehicles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Denergy%2BSolar%2Bvehicles">Measurements of electric fields in the solar wind: Interpretation difficulties</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chertkov, A. D. 1995-01-01 The traditionally measured electric fields in the solar wind plasma (about 1-10 mV/m) are not the natural, primordial ones but are the result of plasma-vehicle interaction. The theory of this interaction is not complete now and current interpretation of the measurements can fail. The state of fully ionized plasma depends on the entropy of the creating source and on the process in which plasma is involved. The increasing twofold of a moving volume in the solar wind (with energy transfer across its surface which is comparable with its whole internal energy) is a more rapid process than the relaxation for the pressure. The presumptive source of the solar wind creation - the induction electric field of the solar origin - has very low entropy. The state of plasma must be very far from the state of thermodynamic equilibrium. The internal energy of plasma can be contained mainly in plasma waves, resonant plasma oscillations, and electric currents. The primordial microscopic oscillating electric fields could be about 1 V/m. It can be checked by special measurements, not ruining the natural plasma state. The tool should be a dielectrical microelectroscope outside the distortion zone of the spacecraft, having been observed from the latter. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720046891&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DMagnetic%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720046891&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DMagnetic%2Benergy">Magnetic energy flow in the solar wind.</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Modisette, J. L. 1972-01-01 Discussion of the effect of rotation (tangential flow) of the solar wind on the conclusions of Whang (1971) suggesting an increase in the solar wind velocity due to the conversion of magnetic energy to kinetic energy. It is shown that the effect of the rotation of the sun on the magnetic energy flow results in most of the magnetic energy being transported by magnetic shear stress near the sun. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880043694&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dconvection%2Bcurrents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880043694&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dconvection%2Bcurrents">Ionospheric traveling convection vortices observed near the polar cleft - A triggered response to sudden changes in the solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Friis-Christensen, E.; Vennerstrom, S.; Mchenry, M. A.; Clauer, C. R. 1988-01-01 Analysis of 20-second resolution magnetometer data from an array of temporary stations operated around Sondre Stromfjord, Greenland, during the summer of 1986 shows the signatures of localized ionospheric traveling convection vortices. An example of an isolated event of this kind observed near 08 local time is presented in detail. This event consists of a twin vortex pattern of convection consistent with the presence of two field-aligned current filaments separated by about 600 km in the east-west direction. This system of currents is observed to move westward (tailward) past the array of stations at about 4 km/sec. The event is associated with relative quiet time ionospheric convection and occurs during an interval of northward IMF. It is, however, associated with a large fluctuation in both the Z and Y components of the IMF and with a large sudden decrease in the solar wind number density. The propagation of the system is inconsistent with existing models of FTE current systems, but nevertheless appears to be related to a readjustment of the magnetopause boundary to a sudden change in the solar wind dynamic pressure and/or to a change in reconnection brought about by a sudden reorientation of the IMF. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM33B2649G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM33B2649G">The Solar Wind-Mars Interaction Boundaries in Three Dimensions</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gruesbeck, J.; Espley, J. R.; Connerney, J. E. P.; DiBraccio, G. A.; Soobiah, Y. I. J. 2017-12-01 The Martian magnetosphere is a product of the interaction of Mars with the interplanetary magnetic field and the supersonic solar wind. A bow shock forms upstream of the planet as the solar wind is diverted around the planet. Closer to the planet another boundary is located that separates the shock-heated solar wind plasma from the planetary plasma in the Martian magnetosphere. The Martian magnetosphere is induced by the pile-up of the interplanetary magnetic field. This induced magnetospheric boundary (IMB) has been referred to by different names, in part due to the observations available at the time. The location of these boundaries have been previously analyzed using data from Phobos 2, Mars Global Surveyor, and Mars Express resulting in models describing their average shapes. Observations of individual transitions demonstrate that it is a boundary with a finite thickness. The MAVEN spacecraft has been in orbit about Mars since November 2014 resulting in many encounters of the spacecraft with the boundaries. Using data from the Particle and Fields Package (PFP), we identify over 1000 bow shock crossings and over 4000 IMB crossings that we use to model the average locations. We model the boundaries as a 3-dimensional surface allowing observations of asymmetry. The average location of the bow shock and IMB lies further from the planet in the southern hemisphere, where stronger crustal fields are present. The MAVEN PFP dataset allows concurrent observations of the magnetic field and plasma environment to investigate the nature of the IMB and the relationship of the boundary to the different plasma signatures. Finally, we model the upstream and downstream encounters of the boundaries separately to produce shell models that quantify the finite thicknesses of the boundaries. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5454225','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5454225">Interaction of the solar wind with comets: a Rosetta perspective</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> 2017-01-01 The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov–Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring--beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the ‘singing’ of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction. This article is part of the themed issue ‘Cometary science after Rosetta’. PMID:28554976 </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active">22</li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active">23</li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22680875','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22680875">Magnetic discontinuities in magnetohydrodynamic turbulence and in the solar wind.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Zhdankin, Vladimir; Boldyrev, Stanislav; Mason, Joanne; Perez, Jean Carlos 2012-04-27 Recent measurements of solar wind turbulence report the presence of intermittent, exponentially distributed angular discontinuities in the magnetic field. In this Letter, we study whether such discontinuities can be produced by magnetohydrodynamic (MHD) turbulence. We detect the discontinuities by measuring the fluctuations of the magnetic field direction, Δθ, across fixed spatial increments Δx in direct numerical simulations of MHD turbulence with an imposed uniform guide field B(0). A large region of the probability density function (pdf) for Δθ is found to follow an exponential decay, proportional to exp(-Δθ/θ(*)), with characteristic angle θ(*)≈(14°)(b(rms)/B(0))(0.65) for a broad range of guide-field strengths. We find that discontinuities observed in the solar wind can be reproduced by MHD turbulence with reasonable ratios of b(rms)/B(0). We also observe an excess of small angular discontinuities when Δx becomes small, possibly indicating an increasing statistical significance of dissipation-scale structures. The structure of the pdf in this case closely resembles the two-population pdf seen in the solar wind. We thus propose that strong discontinuities are associated with inertial-range MHD turbulence, while weak discontinuities emerge from dissipation-range turbulence. In addition, we find that the structure functions of the magnetic field direction exhibit anomalous scaling exponents, which indicates the existence of intermittent structures. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017RSPTA.37560256G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017RSPTA.37560256G">Interaction of the solar wind with comets: a Rosetta perspective</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Glassmeier, Karl-Heinz 2017-05-01 The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov-Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring-beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the `singing' of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction. This article is part of the themed issue 'Cometary science after Rosetta'. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...853..142L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...853..142L">Generation of Kappa Distributions in Solar Wind at 1 au</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Livadiotis, G.; Desai, M. I.; Wilson, L. B., III 2018-02-01 We examine the generation of kappa distributions in the solar wind plasma near 1 au. Several mechanisms are mentioned in the literature, each characterized by a specific relationship between the solar wind plasma features, the interplanetary magnetic field (IMF), and the kappa index—the parameter that governs the kappa distributions. This relationship serves as a signature condition that helps the identification of the mechanism in the plasma. In general, a mechanism that generates kappa distributions involves a single or a series of stochastic or physical processes that induces local correlations among particles. We identify three fundamental solar wind plasma conditions that can generate kappa distributions, noted as (i) Debye shielding, (ii) frozen IMF, and (iii) temperature fluctuations, each one prevailing in different scales of solar wind plasma and magnetic field properties. Moreover, our findings show that the kappa distributions, and thus, their generating mechanisms, vary significantly with solar wind features: (i) the kappa index has different dependence on the solar wind speed for slow and fast modes, i.e., slow wind is characterized by a quasi-constant kappa index, κ ≈ 4.3 ± 0.7, while fast wind exhibits kappa indices that increase with bulk speed; (ii) the dispersion of magnetosonic waves is more effective for lower kappa indices (i.e., further from thermal equilibrium); and (iii) the kappa and polytropic indices are positively correlated, as it was anticipated by the theory. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820058209&hterms=debye+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddebye%2Blength','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820058209&hterms=debye+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddebye%2Blength">Observations of structuring in the downstream region of a large spherical model in a laboratory simulated solar wind plasma</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Intriligator, D. S.; Steele, G. R. 1982-01-01 The effects of inserting a spherical conducting model, large in comparison with the Debye length, into a free streaming high-energy 1 kV) unmagnetized hydrogen plasma are investigated in order to measure energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. Holding the incident plasma parameters constant, transverse profiles of the net Langmuir probe current are plotted at various locations downstream in the model wake and are divided into three regions (the shadow, transition, and boundary). Results attributable to the use of a high-energy plasma show that enhancements in the shadow exist at downstream locations where the Mach ratio is less than one, and turbulence exists in the transition region on the shadow edges and outside in the boundary region. In addition, a small current enhancement is found in the boundary and can be attributed to the plasma/model interaction. It is concluded that many similar features observed by spacecraft downstream from planetary bodies are relatively permanent and are due to the intrinsic nature of the interaction between the solar wind plasma and the obstacle. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770051140&hterms=Krieger&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DKrieger','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770051140&hterms=Krieger&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DKrieger">High coronal structure of high velocity solar wind stream sources</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Nolte, J. T.; Krieger, A. S.; Roelof, E. C.; Gold, R. E. 1977-01-01 It is shown analytically that the transition from a high-speed stream source to the ambient coronal conditions is quite rapid in longitude in the high corona. This sharp eastern coronal boundary for the solar wind stream sources is strongly suggested by the solar wind 'dwells' which appear in plots of solar wind velocity against constant-radial-velocity-approximation source longitudes. The possibility of a systematic velocity-dependent effect in the constant-radial-velocity approximation, which would cause this boundary to appear sharper than it is, is investigated. A velocity-dependent interplanetary propagation effect or a velocity-dependent 'source altitude' are two possible sources of such a systematic effect. It is shown that, for at least some dwells, significant interplanetary effects are not likely. The variation of the Alfvenic critical radius in solar wind dwells is calculated, showing that the high-velocity stream originates from a significantly lower altitude than the ambient solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790009952&hterms=history+gold&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dhistory%2Bgold','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790009952&hterms=history+gold&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dhistory%2Bgold">Prediction of solar energetic particle event histories using real-time particle and solar wind measurements</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Roelof, E. C.; Gold, R. E. 1978-01-01 The comparatively well-ordered magnetic structure in the solar corona during the decline of Solar Cycle 20 revealed a characteristic dependence of solar energetic particle injection upon heliographic longitude. When analyzed using solar wind mapping of the large scale interplanetary magnetic field line connection from the corona to the Earth, particle fluxes display an approximately exponential dependence on heliographic longitude. Since variations in the solar wind velocity (and hence the coronal connection longitude) can severely distort the simple coronal injection profile, the use of real-time solar wind velocity measurements can be of great aid in predicting the decay of solar particle events. Although such exponential injection profiles are commonplace during 1973-1975, they have also been identified earlier in Solar Cycle 20, and hence this structure may be present during the rise and maximum of the cycle, but somewhat obscured by greater temporal variations in particle injection. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH31C2750S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH31C2750S">A quasilinear kinetic model for solar wind electrons and protons instabilities</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sarfraz, M.; Yoon, P. H. 2017-12-01 In situ measurements confirm the anisotropic behavior in temperatures of solar wind species. These anisotropies associated with charge particles are observed to be relaxed. In collionless limit, kinetic instabilities play a significant role to reshape particles distribution. The linear analysis results are encapsulated in inverse relationship between anisotropy and plasma beta based observations fittings techniques, simulations methods, or solution of linearized Vlasov equation. Here amacroscopic quasilinear technique is adopted to confirm inverse relationship through solutions of set of self-consistent kinetic equations. Firstly, for a homogeneous and non-collisional medium, quasilinear kinetic model is employed to display asymptotic variations of core and halo electrons temperatures and saturations of wave energy densities for electromagnetic electron cyclotron (EMEC) instability sourced by, T⊥}>T{∥ . It is shown that, in (β ∥ , T⊥}/T{∥ ) phase space, the saturations stages of anisotropies associated with core and halo electrons lined up on their respective marginal stability curves. Secondly, for case of electrons firehose instability ignited by excessive parallel temperature i.e T⊥}>T{∥ , both electrons and protons are allowed to dynamically evolve in time. It is also observed that, the trajectories of protons and electrons at saturation stages in phase space of anisotropy and plasma beta correspond to proton cyclotron and firehose marginal stability curves, respectively. Next, the outstanding issue that most of observed proton data resides in nearly isotropic state in phase space is interpreted. Here, in quasilinear frame-work of inhomogeneous solar wind system, a set of self-consistent quasilinear equations is formulated to show a dynamical variations of temperatures with spatial distributions. On choice of different initial parameters, it is shown that, interplay of electron and proton instabilities provides an counter-balancing force to slow </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.6925E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6925E">Survey of the spectral properties of turbulence in the solar wind, the magnetospheres of Venus and Earth, at solar minimum and maximum</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Echim, Marius M. 2014-05-01 In the framework of the European FP7 project STORM ("Solar system plasma Turbulence: Observations, inteRmittency and Multifractals") we analyze the properties of turbulence in various regions of the solar system, for the minimum and respectively maximum of the solar activity. The main scientific objective of STORM is to advance the understanding of the turbulent energy transfer, intermittency and multifractals in space plasmas. Specific analysis methods are applied on magnetic field and plasma data provided by Ulysses, Venus Express and Cluster, as well as other solar system missions (e.g. Giotto, Cassini). In this paper we provide an overview of the spectral properties of turbulence derived from Power Spectral Densities (PSD) computed in the solar wind (from Ulysses, Cluster, Venus Express) and at the interface of planetary magnetospheres with the solar wind (from Venus Express, Cluster). Ulysses provides data in the solar wind between 1992 and 2008, out of the ecliptic, at radial distances ranging between 1.3 and 5.4 AU. We selected only those Ulysses data that satisfy a consolidated set of selection criteria able to identify "pure" fast and slow wind. We analyzed Venus Express data close to the orbital apogee, in the solar wind, at 0.72 AU, and in the Venus magnetosheath. We investigated Cluster data in the solar wind (for time intervals not affected by planetary ions effects), the magnetosheath and few crossings of other key magnetospheric regions (cusp, plasma sheet). We organize our PSD results in three solar wind data bases (one for the solar maximum, 1999-2001, two for the solar minimum, 1997-1998 and respectively, 2007-2008), and two planetary databases (one for the solar maximum, 2000-2001, that includes PSD obtained in the terrestrial magnetosphere, and one for the solar minimum, 2007-2008, that includes PSD obtained in the terrestrial and Venus magnetospheres and magnetosheaths). In addition to investigating the properties of turbulence for the minimum </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990070480&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990070480&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolar%2Bintensity%2Bmeasurement">Solar Wind Speed Structure in the Inner Corona at 3-12 Ro</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Woo, Richard 1995-01-01 Estimates of solar wind speed obtained by Armstrong et al. [1986] based on 1983 VLA multiple-station intensity scintillation measurements inside 12 R(sub o) have been correlated with the electron density structure observed in white-light coronagraph measurements. The observed large- scale and apparently systematic speed variations are found to depend primarily on changes in heliographic latitude and longitude, which leads to the first results on large-scale speed structure in the acceleration region of the solar wind. Over an equatorial hole, solar wind speed is relatively steady, with peak-to-peak variations of 50 km/s and an average of 230 km/s. In contrast, the near-Sun flow speed across the streamer belt shows regular large-scale variations in the range of 100-300 km/s. Based on four groups of data, the gradient is 36 km/s per degree in heliocentric coordinates (corresponding to a rise of 260 km/s over a spatial distance on the Sun of two arcmin) with a standard deviation of 2.4 km/s per degree. The lowest speeds most likely coincide with the stalks of coronal streamers observed in white-light measurements. The detection of significant wind shear over the streamer belt is consistent with in situ and scintillation measurements showing that the density spectrum has a power-law form characteristic of fully developed turbulence over a much broader range of scales than in neighboring regions. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720012210','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720012210">Collisionless solar wind protons: A comparison of kinetic and hydrodynamic descriptions</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Leer, E.; Holzer, T. E. 1971-01-01 Kinetic and hydrodynamic descriptions of a collisionless solar wind proton gas are compared. Heat conduction and viscosity are neglected in the hydrodynamic formulation but automatically included in the kinetic formulation. The results of the two models are very nearly the same, indicating that heat conduction and viscosity are not important in the solar wind proton gas beyond about 0.1 AU. It is concluded that the hydrodynamic equations provide a valid description of the collisionless solar wind protons, and hence that future models of the quiet solar wind should be based on a hydrodynamic formulation. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH31A2710H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH31A2710H">Assessment of Predictive Capabilities of L1 Orbiters using Realtime Solar Wind Data</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Holmes, J.; Kasper, J. C.; Welling, D. T. 2017-12-01 Realtime measurements of solar wind conditions at L1 point allow us to predict geomagnetic activity at Earth up to an hour in advance. These predictions are quantified in the form of geomagnetic indices such as Kp and Ap, allowing for a concise, standardized prediction and measurement system. For years, the Space Weather Prediction Center used ACE realtime solar wind data to develop its one and four-hour Kp forecasts, but has in the past year switched to using DSCOVR data as its source. In this study, the performance of both orbiters in predicting Kp over the course of one month was assessed in an attempt to determine whether or not switching to DSCOVR data has resulted in improved forecasts. The period of study was chosen to encompass a time when the satellites were close to each other, and when moderate to high activity was observed. Kp predictions were made using the Geospace Model, part of the Space Weather Modeling Framework, to simulate conditions based on observed solar wind parameters. The performance of each satellite was assessed by comparing the model output to observed data. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720049125&hterms=enrichment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Denrichment','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720049125&hterms=enrichment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Denrichment">Solar flares and solar wind helium enrichments - July 1965-July 1967.</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hirshberg, J.; Bame, S. J.; Robbins, D. E. 1972-01-01 It has previously been suggested that the very high relative abundances of helium occasionally observed in the solar wind mark the plasma accelerated by major solar flares. To confirm this hypothesis, we have studied the 43 spectra with He/H greater than 15% that were observed among 10,300 spectra collected by Vela 3 between July 1965-July 1967. Six new flare-enhancement events are discussed in this paper. It is concluded that the association of helium enhancements with major flares is real, nonrandom, and very strong. With this study, there are 12 cases of reliable associations between helium enhancements and flares reported in the literature. The general characteristics of these events are discussed. It is found that the flares are typically large and bright (2B or 3B), often they produce cosmic ray protons, and they are widely distributed in solar longitude. A qualitative discussion of some of the possibilities for the source of helium enhanced plasma is presented. It is suggested that the helium enriched plasma may be the piston producing the shock causing the Type II radio emission. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SSRv..210..227C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SSRv..210..227C">Minimal Magnetic States of the Sun and the Solar Wind: Implications for the Origin of the Slow Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cliver, E. W.; von Steiger, R. 2017-09-01 During the last decade it has been proposed that both the Sun and the solar wind have minimum magnetic states, lowest order levels of magnetism that underlie the 11-yr cycle as well as longer-term variability. Here we review the literature on basal magnetic states at the Sun and in the heliosphere and draw a connection between the two based on the recent deep 2008-2009 minimum between cycles 23 and 24. In particular, we consider the implications of the low solar activity during the recent minimum for the origin of the slow solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AAS...22440205W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AAS...22440205W">Solar Wind Acceleration: Modeling Effects of Turbulent Heating in Open Flux Tubes</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Woolsey, Lauren N.; Cranmer, Steven R. 2014-06-01 We present two self-consistent coronal heating models that determine the properties of the solar wind generated and accelerated in magnetic field geometries that are open to the heliosphere. These models require only the radial magnetic field profile as input. The first code, ZEPHYR (Cranmer et al. 2007) is a 1D MHD code that includes the effects of turbulent heating created by counter-propagating Alfven waves rather than relying on empirical heating functions. We present the analysis of a large grid of modeled flux tubes (> 400) and the resulting solar wind properties. From the models and results, we recreate the observed anti-correlation between wind speed at 1 AU and the so-called expansion factor, a parameterization of the magnetic field profile. We also find that our models follow the same observationally-derived relation between temperature at 1 AU and wind speed at 1 AU. We continue our analysis with a newly-developed code written in Python called TEMPEST (The Efficient Modified-Parker-Equation-Solving Tool) that runs an order of magnitude faster than ZEPHYR due to a set of simplifying relations between the input magnetic field profile and the temperature and wave reflection coefficient profiles. We present these simplifying relations as a useful result in themselves as well as the anti-correlation between wind speed and expansion factor also found with TEMPEST. Due to the nature of the algorithm TEMPEST utilizes to find solar wind solutions, we can effectively separate the two primary ways in which Alfven waves contribute to solar wind acceleration: 1) heating the surrounding gas through a turbulent cascade and 2) providing a separate source of wave pressure. We intend to make TEMPEST easily available to the public and suggest that TEMPEST can be used as a valuable tool in the forecasting of space weather, either as a stand-alone code or within an existing modeling framework. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750043957&hterms=dependency&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddependency','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750043957&hterms=dependency&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddependency">The latitude dependencies of the solar wind. [of interplanetary magnetic field polarity and configurations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Rosenberg, R. L.; Winge, C. R., Jr. 1974-01-01 The motion of spacecraft following the earth's orbit occurs within the solar latitude range of 7 deg 15 min N on approximately September 7 to 7 deg 15 min S on approximately March 6. The latitude dependencies so far detected within this range have shown that the photospheric dipole-like field of the sun makes very important contributions to the interplanetary magnetic field (IMF) observed near the ecliptic. Changes in geomagnetic activity from even to odd numbered 11-year solar cycles are related to changes in the sun's dipolar field. The north-south IMF component and meridional, nonradial flow are important to a complete understanding of steady-state solar wind dynamics. Coronal conditions must be latitude-dependent in a way that accounts for the observed latitude dependence of the velocity and density of the solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26207472','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26207472">Inertial-Range Reconnection in Magnetohydrodynamic Turbulence and in the Solar Wind.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Lalescu, Cristian C; Shi, Yi-Kang; Eyink, Gregory L; Drivas, Theodore D; Vishniac, Ethan T; Lazarian, Alexander 2015-07-10 In situ spacecraft data on the solar wind show events identified as magnetic reconnection with wide outflows and extended "X lines," 10(3)-10(4) times ion scales. To understand the role of turbulence at these scales, we make a case study of an inertial-range reconnection event in a magnetohydrodynamic simulation. We observe stochastic wandering of field lines in space, breakdown of standard magnetic flux freezing due to Richardson dispersion, and a broadened reconnection zone containing many current sheets. The coarse-grain magnetic geometry is like large-scale reconnection in the solar wind, however, with a hyperbolic flux tube or apparent X line extending over integral length scales. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSH13B4118L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSH13B4118L">Analysis of Solar Wind Plasma Properties of Co-Rotating Interaction Regions at Mars with MSL/RAD</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lohf, H.; Kohler, J.; Zeitlin, C. J.; Ehresmann, B.; Guo, J.; Wimmer-Schweingruber, R. F.; Hassler, D.; Reitz, G.; Posner, A.; Heber, B.; Appel, J. K.; Matthiae, D.; Brinza, D. E.; Weigle, E.; Böttcher, S. I.; Burmeister, S.; Martin-Garcia, C.; Boehm, E.; Rafkin, S. C.; Kahanpää, H.; Martín-Torres, J.; Zorzano, M. P. 2014-12-01 The measurements of the Radiation Assessment Detector (RAD) onboard Mars Science Laboratory's rover Curiosity have given us the very first opportunity to evaluate the radiation environment on the surface of Mars, which consists mostly of Galactic Cosmic Rays (GCRs) and secondary particles created in the Martian Atmosphere. The solar wind can have an influence on the modulation of the GCR, e.g. when the fast solar wind (~ 750 km/s) interacts with the slow solar wind (~ 400 km/s) at so-called Stream Interaction Regions (SIRs) resulting in an enhancement of the local magnetic field which could affect the shielding of GCRs. SIRs often occur periodically as Co-rotating Interaction Regions (CIRs) which may-be observed at Mars as a decrease in the radiation data measured by MSL/RAD. Considering the difference of the Earth-Mars orbit, we correlate these in-situ radiation data at Mars with the solar wind properties measured by spacecrafts at 1 AU, with the aim to eventually determine the solar wind properties at Mars based on MSL/RAD measurements. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010022102','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010022102">MACS, An Instrument and a Methodology for Simultaneous and Global Measurements of the Coronal Electron Temperature and the Solar Wind Velocity on the Solar Corona</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Reginald, Nelson L. 2000-01-01 In Cram's theory for the formation of the K-coronal spectrum he observed the existence of temperature sensitive anti-nodes, which were separated by temperature insensitive nodes, at certain wave-lengths in the K-coronal spectrum. Cram also showed these properties were remarkably independent of altitude above the solar limb. In this thesis Cram's theory has been extended to incorporate the role of the solar wind in the formation of the K-corona, and we have identified both temperature and wind sensitive intensity ratios. The instrument, MACS, for Multi Aperture Coronal Spectrometer, a fiber optic based spectrograph, was designed for global and simultaneous measurements of the thermal electron temperature and the solar wind velocity in the solar corona. The first ever experiment of this nature was conducted in conjunction with the total solar eclipse of 11 August 1999 in Elazig, Turkey. Here twenty fiber optic tips were positioned in the focal plane of the telescope to observe simultaneously at many different latitudes and two different radial distances in the solar corona. The other ends were vertically stacked and placed at the primary focus of the spectrograph. By isolating the K-coronal spectrum from each fiber the temperature and the wind sensitive intensity ratios were calculated. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4604519','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4604519">Impacts of wind stilling on solar radiation variability in China</a> <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Lin, Changgui; Yang, Kun; Huang, Jianping; Tang, Wenjun; Qin, Jun; Niu, Xiaolei; Chen, Yingying; Chen, Deliang; Lu, Ning; Fu, Rong 2015-01-01 Solar dimming and wind stilling (slowdown) are two outstanding climate changes occurred in China over the last four decades. The wind stilling may have suppressed the dispersion of aerosols and amplified the impact of aerosol emission on solar dimming. However, there is a lack of long-term aerosol monitoring and associated study in China to confirm this hypothesis. Here, long-term meteorological data at weather stations combined with short-term aerosol data were used to assess this hypothesis. It was found that surface solar radiation (SSR) decreased considerably with wind stilling in heavily polluted regions at a daily scale, indicating that wind stilling can considerably amplify the aerosol extinction effect on SSR. A threshold value of 3.5 m/s for wind speed is required to effectively reduce aerosols concentration. From this SSR dependence on wind speed, we further derived proxies to quantify aerosol emission and wind stilling amplification effects on SSR variations at a decadal scale. The results show that aerosol emission accounted for approximately 20% of the typical solar dimming in China, which was amplified by approximately 20% by wind stilling. PMID:26463748 </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023411','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023411">The Solar Wind as a Magnetofluid Turbulence Laboratory</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Goldstein, Melvyn L. 2011-01-01 The solar wind is the Sun's exosphere. As the solar atmosphere expands into interplanetary space, it is accelerated and heated. Data from spacecraft located throughout the heliosphere have revealed that this exosphere has velocities of several hundred kilometers/sec, densities at Earth orbit of about 5 particles/cu cm, and an entrained magnetic field that at Earth orbit that is about 5 10-5 Gauss. A fascinating feature of the solar wind is that the magnetic field fluctuates in a way that is highly reminiscent of "Alfven waves, i.e., the fluctuating magnetic fields are more-or-less aligned with fluctuations in the velocity of the plasma and, with proper normalization, have approximately equal magnitudes. The imperfect (observed) alignment leads to a variety of complex interactions. In many respects, the flow patterns appear to be an example of fully developed magneto fluid turbulence. Recently, the dissipation range of this turbulence has been studied using search coil magnetometer data from the STAFF instrument on the four Cluster spacecraft. I will attempt to give an overview of selected properties of this large-scale and small-scale turbulence. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active">23</li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active">24</li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070008094&hterms=Solar+still&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DSolar%2Bstill','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070008094&hterms=Solar+still&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DSolar%2Bstill">A New Look at Some Solar Wind Turbulence Puzzles</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Roberts, Aaron 2006-01-01 Some aspects of solar wind turbulence have defied explanation. While it seems likely that the evolution of Alfvenicity and power spectra are largely explained by the shearing of an initial population of solar-generated Alfvenic fluctuations, the evolution of the anisotropies of the turbulence does not fit into the model so far. A two-component model, consisting of slab waves and quasi-two-dimensional fluctuations, offers some ideas, but does not account for the turning of both wave-vector-space power anisotropies and minimum variance directions in the fluctuating vectors as the Parker spiral turns. We will show observations that indicate that the minimum variance evolution is likely not due to traditional turbulence mechanisms, and offer arguments that the idea of two-component turbulence is at best a local approximation that is of little help in explaining the evolution of the fluctuations. Finally, time-permitting, we will discuss some observations that suggest that the low Alfvenicity of many regions of the solar wind in the inner heliosphere is not due to turbulent evolution, but rather to the existence of convected structures, including mini-clouds and other twisted flux tubes, that were formed with low Alfvenicity. There is still a role for turbulence in the above picture, but it is highly modified from the traditional views. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000GeoRL..27.2165L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000GeoRL..27.2165L">Magnetosphere on May 11, 1999, the day the solar wind almost disappeared: II. Magnetic pulsations in space and on the ground</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Le, G.; Chi, P. J.; Goedecke, W.; Russell, C. T.; Szabo, A.; Petrinec, S. M.; Angelopoulos, V.; Reeves, G. D.; Chun, F. K. 2000-08-01 Simultaneous observations by Wind and IMP-8 in the upstream region on May 11, 1999, when the solar wind density was well below its usual values and the IMF was generally weakly northward, indicate there were upstream waves present in the foreshock, but wave power was an order of magnitude weaker than usual due to an extremely weak bow shock and tenuous solar wind plasma. Magnetic pulsations in the magnetosphere have been observed in the magnetic field data from Polar and at mid-latitude ground stations. By comparing May 11 with a control day under normal solar wind conditions and with a similar foreshock geometry, we find that the magnetosphere was much quieter than usual. The Pc 3-4 waves were nearly absent in the dayside magnetosphere both at Polar and as seen at mid-latitude ground stations even through the foreshock geometry was favorable for the generation of these waves. Since the solar wind speed was not unusual on this day, these observations suggest that it is the Mach number of the solar wind flow relative to the magnetosphere that controls the amplitude of Pc 3-4 waves in the magnetosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH51E..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH51E..08S">Correlation of Magnetic Fields with Solar Wind Plasma Parameters at 1AU</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shen, F. 2017-12-01 The physical parameters of the solar wind observed in-situ near 1AU have been studied for several decades, and relationships between them, such as the positive correlation between the solar wind plasma temperature T and velocity V, and the negative correlation between density N and velocity V, are well known. However, the magnetic field intensity does not appear to be well correlated with any individual plasma parameter. In this paper, we discuss previously under-reported correlations between B and the combined plasma parameters √NV2 as well as between B and √NT. These two correlations are strong during the periods of corotating interaction regions and high speed streams, moderate during intervals of slow solar wind, and rather poor during the passage of interplanetary coronal mass ejections. The results indicate that the magnetic pressure in the solar wind is well correlated both with the plasma dynamic pressure and the thermal pressure. Then, we employ a 3D MHD model to simulate the formation of the relationships between the magnetic strength B and √NV2 as well as √NT observed at 1AU. The inner boundary condition is derived by empirical models, with the magnetic field and density are optional. Five kinds of boundary conditions at the inner boundary of heliosphere are tested. In the cases that the magnetic field is related to speed at the inner boundary, the correlation coefficients between B and √NV2 as well as between B and √NT are even higher than that in the observational results. At 1AU the simulated radial magnetic field shows little latitude dependence, which matches the observation of Ulysses. Most of the modeled characters in these cases are closer to observation than others. This inner boundary condition may more accurately characterize Sun's magnetic influence on the heliosphere. The new input may be able to improve the simulation of CME propagation in the inner heliosphere and the space weather forecasting. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970022574','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970022574">Self-Consistent and Time-Dependent Solar Wind Models</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ong, K. K.; Musielak, Z. E.; Rosner, R.; Suess, S. T.; Sulkanen, M. E. 1997-01-01 We describe the first results from a self-consistent study of Alfven waves for the time-dependent, single-fluid magnetohydrodynamic (MHD) solar wind equations, using a modified version of the ZEUS MHD code. The wind models we examine are radially symmetrical and magnetized; the initial outflow is described by the standard Parker wind solution. Our study focuses on the effects of Alfven waves on the outflow and is based on solving the full set of the ideal nonlinear MHD equations. In contrast to previous studies, no assumptions regarding wave linearity, wave damping, and wave-flow interaction are made; thus, the models naturally account for the back-reaction of the wind on the waves, as well as for the nonlinear interaction between different types of MHD waves. Our results clearly demonstrate when momentum deposition by Alfven waves in the solar wind can be sufficient to explain the origin of fast streams in solar coronal holes; we discuss the range of wave amplitudes required to obtained such fast stream solutions. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22370547-evolution-turbulence-expanding-solar-wind-numerical-study','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22370547-evolution-turbulence-expanding-solar-wind-numerical-study">Evolution of turbulence in the expanding solar wind, a numerical study</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Dong, Yue; Grappin, Roland; Verdini, Andrea, E-mail: Yue.Dong@lpp.polytechnique.fr, E-mail: verdini@arcetri.astro.it, E-mail: grappin@lpp.polytechnique.fr 2014-10-01 We study the evolution of turbulence in the solar wind by solving numerically the full three-dimensional (3D) magnetohydrodynamic (MHD) equations embedded in a radial mean wind. The corresponding equations (expanding box model or EBM) have been considered earlier but never integrated in 3D simulations. Here, we follow the development of turbulence from 0.2 AU up to about 1.5 AU. Starting with isotropic spectra scaling as k {sup –1}, we observe a steepening toward a k {sup –5/3} scaling in the middle of the wave number range and formation of spectral anisotropies. The advection of a plasma volume by the expandingmore » solar wind causes a non-trivial stretching of the volume in directions transverse to radial and the selective decay of the components of velocity and magnetic fluctuations. These two effects combine to yield the following results. (1) Spectral anisotropy: gyrotropy is broken, and the radial wave vectors have most of the power. (2) Coherent structures: radial streams emerge that resemble the observed microjets. (3) Energy spectra per component: they show an ordering in good agreement with the one observed in the solar wind at 1 AU. The latter point includes a global dominance of the magnetic energy over kinetic energy in the inertial and f {sup –1} range and a dominance of the perpendicular-to-the-radial components over the radial components in the inertial range. We conclude that many of the above properties are the result of evolution during transport in the heliosphere, and not just the remnant of the initial turbulence close to the Sun.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMSH12A0861S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMSH12A0861S">Supercharging of the Lunar Surface by Solar Wind Halo Electrons</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Stubbs, T. J.; Farrell, W. M.; Collier, M. R.; Halekas, J. S.; Delory, G. T.; Holland, M. P.; Vondrak, R. R. 2007-12-01 Lunar surface potentials can reach several kilovolts negative during Solar Energetic Particle (SEPs) events, as indicated by recent analysis of data from the Lunar Prospector Electron Reflectometer (LP/ER). The lunar surface- plasma interactions that result in such extreme surface potentials are poorly characterized and understood. Extreme lunar surface charging, and the associated electrostatic discharges and transport of charged dust, will likely present significant hazards to future human explorers. This is of particular concern near the terminator and polar regions, such as the South Pole/Aiken Basin site planned for NASA's manned outpost. It is the flux of electrons from the ambient plasma that charges the surface of the Moon to negative potentials. In the solar wind, the electron temperature is typically ~10 eV which tends to charge the lunar surface to ~100 V negative in shadow. However, during space weather events the solar wind electrons are often better described by the sum of two Maxwellian distributions, referred to as the "core" and "halo" components. The core electrons are relatively cool and dense (e.g., ~10 eV and ~10/cc), whereas the halo electrons are hot and tenuous (e.g., ~100 eV and ~0.1/cc). Despite, the tenuous nature of the halo electrons, our surface charging model - using core and halo electron data derived from the Solar Wind Experiment (SWE) aboard the Wind spacrcraft - predicts that they are capable of "supercharging" the lunar surface to kilovolt potentials during space weather events, which could explain the LP/ER observations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960020490','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960020490">The Outer Heliosphere: Solar Wind, Cosmic Ray and VLF Radio Emission Variations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> McNutt, Ralph L., Jr. 1995-01-01 The Voyager 1 and 2 spacecraft now 45 astronomical units (AU) from Earth continue to monitor the outer heliosphere field and particles environment on a daily basis during their journey to the termination shock of the solar wind. Strong transient shocks continue to be detected in the solar wind plasma. The largest of these are associated with Global Merged Interaction Regions (GMIR's) which, in turn, block cosmic ray entry into the inner heliosphere and are apparently responsible for triggering the two major episodes of VLF radio emissions now thought to come from the heliopause. Distance estimates to the termination shock are consistent with those determined from observations of anomalous cosmic rays. Current observations and implications for heliospheric structure are discussed. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890053926&hterms=solar+two&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsolar%2Btwo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890053926&hterms=solar+two&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsolar%2Btwo">Long-term changes in solar wind elemental and isotopic ratios - A comparison of two lunar ilmenites of different antiquities</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Becker, Richard H.; Pepin, Robert O. 1989-01-01 The solar wind components in two lunar ilmenites are examined. The noble gas and nitrogen elemental and isotopic abundances of lunar regolith breccia sample 79035, assumed to have been exposed to solar winds more than 2 Ga ago, are analyzed using stepwise oxidation and pyrolysis. This sample is compared with the data of Frick et al. (1988) for soil sample 71501, recently exposed to solar winds. It is observed that the two elements differ in terms of xenon abundance, helium and neon isotopic rates, and He/Ar elemental ratios. It is concluded that there have been isotopic and elemental abundance changes in solar wind composition over time. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110013339','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110013339">The Character of the Solar Wind, Surface Interactions, and Water</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Farrell, William M. 2011-01-01 We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH11B2441P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH11B2441P">On the radial evolution of reflection-driven turbulence in the inner solar wind in preparation for Parker Solar Probe</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Perez, J. C.; Chandran, B. D. G. 2017-12-01 In this work we present recent results from high-resolution direct numerical simulations and a phenomenological model that describes the radial evolution of reflection-driven Alfven Wave turbulence in the solar atmosphere and the inner solar wind. The simulations are performed inside a narrow magnetic flux tube that models a coronal hole extending from the solar surface through the chromosphere and into the solar corona to approximately 21 solar radii. The simulations include prescribed empirical profiles that account for the inhomogeneities in density, background flow, and the background magnetic field present in coronal holes. Alfven waves are injected into the solar corona by imposing random, time-dependent velocity and magnetic field fluctuations at the photosphere. The phenomenological model incorporates three important features observed in the simulations: dynamic alignment, weak/strong nonlinear AW-AW interactions, and that the outward-propagating AWs launched by the Sun split into two populations with different characteristic frequencies. Model and simulations are in good agreement and show that when the key physical parameters are chosen within observational constraints, reflection-driven Alfven turbulence is a plausible mechanism for the heating and acceleration of the fast solar wind. By flying a virtual Parker Solar Probe (PSP) through the simulations, we will also establish comparisons between the model and simulations with the kind of single-point measurements that PSP will provide. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15716946','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15716946">Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> 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 2005-02-17 The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind 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 solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind 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 solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind 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 solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760046362&hterms=planetary+boundaries&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dplanetary%2Bboundaries','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760046362&hterms=planetary+boundaries&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dplanetary%2Bboundaries">Depletion of solar wind plasma near a planetary boundary</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Zwan, B. J.; Wolf, R. A. 1976-01-01 A mathematical model is presented that describes the squeezing of solar wind plasma out along interplanetary magnetic field lines in the region between the bow shock and the effective planetary boundary (in the case of the earth, the magnetopause). In the absence of local magnetic merging the squeezing process should create a 'depletion layer', a region of very low plasma density just outside the magnetopause. Numerical solutions are obtained for the dimensionless magnetohydrodynamic equations describing this depletion process for the case where the solar wind magnetic field is perpendicular to the solar wind flow direction. For the case of the earth, the theory predicts that the density should be reduced by a factor exceeding 2 in a layer about 700-1300 km thick if the Alfven Mach number in the solar wind, is equal to 8. Scaling of the model calculations to Venus and Mars suggests layer thicknesses about 1/10 and 1/15 those of the earth, respectively, neglecting diffusion and ionospheric effects. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930032138&hterms=solar+two&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsolar%2Btwo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930032138&hterms=solar+two&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsolar%2Btwo">A parameter study of the two-fluid solar wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sandbaek, Ornulf; Leer, Egil; Holzer, Thomas E. 1992-01-01 A two-fluid model of the solar wind was introduced by Sturrock and Hartle (1966) and Hartle and Sturrock (1968). In these studies the proton energy equation was integrated neglecting the heat conductive term. Later several authors solved the equations for the two-fluid solar wind model keeping the proton heat conductive term. Methods where the equations are integrated simultaneously outward and inward from the critical point were used. The equations were also integrated inward from a large heliocentric distance. These methods have been applied to cases with low coronal base electron densities and high base temperatures. In this paper we present a method of integrating the two-fluid solar wind equations using an iteration procedure where the equations are integrated separately and the proton flux is kept constant during the integrations. The technique is applicable for a wide range of coronal base densities and temperatures. The method is used to carry out a parameter study of the two-fluid solar wind. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19238948','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19238948">Air emissions due to wind and solar power.</a> <a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Katzenstein, Warren; Apt, Jay 2009-01-15 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. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH53A2550G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH53A2550G">Studying Solar Wind Properties Around CIRs and Their Effects on GCR Modulation</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ghanbari, K.; Florinski, V. A. 2017-12-01 Corotating interaction region (CIR) events occur when a fast solar wind stream overtakes slow solar wind, forming a compression region ahead and a rarefaction region behind in the fast solar wind. Usually this phenomena occurs along with a crossing of heliospheric current sheet which is the surface separating solar magnetic fields of opposing polarities. In this work, the solar plasma data provided by the ACE science center are utilized to do a superposed epoch analysis on solar parameters including proton density, proton temperature, solar wind speed and solar magnetic field in order to study how the variations of these parameters affect the modulation of galactic cosmic rays. Magnetic fluctuation variances in different parts a of CIR are computed and analyzed using similar techniques in order to understand the cosmic-ray diffusive transport in these regions. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.1061T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.1061T">A Generalized Equatorial Model for the Accelerating Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tasnim, S.; Cairns, Iver H.; Wheatland, M. S. 2018-02-01 A new theoretical model for the solar wind is developed that includes the wind's acceleration, conservation of angular momentum, deviations from corotation, and nonradial velocity and magnetic field components from an inner boundary (corresponding to the onset of the solar wind) to beyond 1 AU. The model uses a solution of the time-steady isothermal equation of motion to describe the acceleration and analytically predicts the Alfvénic critical radius. We fit the model to near-Earth observations of the Wind spacecraft during the solar rotation period of 1-27 August 2010. The resulting data-driven model demonstrates the existence of noncorotating, nonradial flows and fields from the inner boundary (r = rs) outward and predicts the magnetic field B = (Br,Bϕ), velocity v = (vr,vϕ), and density n(r,ϕ,t), which vary with heliocentric distance r, heliolatitude ϕ, and time t in a Sun-centered standard inertial plane. The description applies formally only in the equatorial plane. In a frame corotating with the Sun, the transformed velocity v' and a field B' are not parallel, resulting in an electric field with a component Ez' along the z axis. The resulting E'×B'=E'×B drift lies in the equatorial plane, while the ∇B and curvature drifts are out of the plane. Together these may lead to enhanced scattering/heating of sufficiently energetic particles. The model predicts that deviations δvϕ from corotation at the inner boundary are common, with δvϕ(rs,ϕs,ts) comparable to the transverse velocities due to granulation and supergranulation motions. Abrupt changes in δvϕ(rs,ϕs,ts) are interpreted in terms of converging and diverging flows at the cell boundaries and centers, respectively. Large-scale variations in the predicted angular momentum demonstrate that the solar wind can drive vorticity and turbulence from near the Sun to 1 AU and beyond. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPJ10090M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPJ10090M">The Colorado Solar Wind Experiment</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Munsat, Tobin; Han, Jia; Horanyi, Mihaly; Ulibarri, Zach; Wang, Xu; Yeo, Lihsia 2016-10-01 The Colorado Solar Wind Experiment (CSWE) is a new device developed at the Institute for Modeling Plasma, Atmospheres, and Cosmic Dust (IMPACT) at the University of Colorado. This large ion source is for studies of the interaction of solar wind plasma with planetary surfaces and cosmic dust, and for the investigation of plasma wake physics. With a plasma beam diameter of 12 cm at the source, ion energies of up to 1 keV, and ion flows of up to 1 mA/cm2, a large cross-section Kaufman Ion Source is used to create steady state plasma flow to model the solar wind in an experimental vacuum chamber. Chamber pressure can be reduced to 3e-5 Torr under operating conditions to suppress ion-neutral collisions and create a uniform ion velocity distribution. Diagnostic instruments such as a double Langmuir probe and an ion energy analyzer are mounted on a two-dimensional translation stage that allow the beam to be characterized throughout the chamber. Early experiments include the measurement of dust grain charging from the interaction with flowing plasma, and measurements of the plasma sheath created by the interaction of the flowing plasma impinging on a surface with a dipole magnetic field. This poster will describe the facility and the scientific results obtained to date. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH13D..05W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH13D..05W">Quiet-Time Suprathermal ( 0.1-1.5 keV) Electrons in the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wang, L.; Tao, J.; Zong, Q.; Li, G.; Salem, C. S.; Wimmer-Schweingruber, R. F.; He, J.; Tu, C.; Bale, S. D. 2016-12-01 We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND/3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ and effective temperature Teff. We also calculate the number density n and average energy Eavg of strahl and halo electrons by integrating the electron measurements between ˜0.1 and 1.5 keV. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity). </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...820...22T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...820...22T">Quiet-time Suprathermal (~0.1-1.5 keV) Electrons in the Solar Wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tao, Jiawei; Wang, Linghua; Zong, Qiugang; Li, Gang; Salem, Chadi S.; Wimmer-Schweingruber, Robert F.; He, Jiansen; Tu, Chuanyi; Bale, Stuart D. 2016-03-01 We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ and effective temperature Teff. We also calculate the number density n and average energy Eavg of strahl and halo electrons by integrating the electron measurements between ˜0.1 and 1.5 keV. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity). </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014acm..conf..438R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014acm..conf..438R">Solar-wind velocity measurements from near-Sun comets C/2011 W3 (Lovejoy), C/2011 L4 (Pan-STARRS), and C/2012 S1 (ISON)</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ramanjooloo, Y.; Jones, G. H.; Coates, A.; Owens, M. J.; Battams, K. 2014-07-01 Since the mid-20th century, comets' plasma (type I) tails have been studied as natural probes of the solar wind [1]. Comets have induced magnetotails, formed through the draping of the heliospheric magnetic field by the velocity shear in the mass-loaded solar wind. These can be easily observed remotely as the comets' plasma tails, which generally point away from the Sun. Local solar-wind conditions directly influence the morphology and dynamics of a comet's plasma tail. During ideal observing geometries, the orientation and structure of the plasma tail can reveal large-scale and small-scale variations in the local solar-wind structure. These variations can be manifested as tail condensations, kinks, and disconnection events. Over 50 % of observed catalogued comets are sungrazing comets [2], fragments of three different parent comets. Since 2011, two bright new comets, C/2011 W3 [3] (from hereon comet Lovejoy) and C/2012 S1 [4] (hereon comet ISON) have experienced extreme solar-wind conditions and insolation of their nucleus during their perihelion passages, approaching to within 8.3×10^5 km (1.19 solar radii) and 1.9×10^6 km (2.79 solar radii) of the solar centre. They each displayed a prominent plasma tail, proving to be exceptions amongst the observed group of sungrazing comets. These bright sungrazers provide unprecedented access to study the solar wind in the heretofore unprobed innermost region of the solar corona. The closest spacecraft in-situ sampling of the solar wind by the Helios probes reached 0.29 au. For this study, we define a sungrazing comet as one with its perihelion within the solar Roche limit (3.70 solar radii). We also extend this study to include C/2011 L4 [5] (comet Pan-STARRS), a comet with a much further perihelion distance of 0.302 au. The technique employed in this study was first established by analysing geocentric amateur observations of comets C/2001 Q4 (NEAT) and C/2004 Q2 (Machholz) [7]. These amateur images, obtained with modern </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active">24</li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active">25</li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12211320H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12211320H">Flows, Fields, and Forces in the Mars-Solar Wind Interaction</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Halekas, J. S.; Brain, D. A.; Luhmann, J. G.; DiBraccio, G. A.; Ruhunusiri, S.; Harada, Y.; Fowler, C. M.; Mitchell, D. L.; Connerney, J. E. P.; Espley, J. R.; Mazelle, C.; Jakosky, B. M. 2017-11-01 We utilize suprathermal ion and magnetic field measurements from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, organized by the upstream magnetic field, to investigate the morphology and variability of flows, fields, and forces in the Mars-solar wind interaction. We employ a combination of case studies and statistical investigations to characterize the interaction in both quasi-parallel and quasi-perpendicular regions and under high and low solar wind Mach number conditions. For the first time, we include a detailed investigation of suprathermal ion temperature and anisotropy. We find that the observed magnetic fields and suprathermal ion moments in the magnetosheath, bow shock, and upstream regions have observable asymmetries controlled by the interplanetary magnetic field, with particularly large asymmetries found in the ion parallel temperature and anisotropy. The greatest temperature anisotropies occur in quasi-perpendicular regions of the magnetosheath and under low Mach number conditions. These results have implications for the growth and evolution of wave-particle instabilities and their role in energy transport and dissipation. We utilize the measured parameters to estimate the average ion pressure gradient, J × B, and v × B macroscopic force terms. The pressure gradient force maintains nearly cylindrical symmetry, while the J × B force has larger asymmetries and varies in magnitude in comparison to the pressure gradient force. The v × B force felt by newly produced planetary ions exceeds the other forces in magnitude in the magnetosheath and upstream regions for all solar wind conditions. </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170004864&hterms=gravity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dgravity','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170004864&hterms=gravity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dgravity">Reconnection-Driven Coronal-Hole Jets with Gravity and Solar Wind</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Karpen, J. T.; Devore, C. R.; Antiochos, S. K.; Pariat, E. 2017-01-01 Coronal-hole jets occur ubiquitously in the Sun's coronal holes, at EUV and X-ray bright points associated with intrusions of minority magnetic polarity. The embedded-bipole model for these jets posits that they are driven by explosive, fast reconnection between the stressed closed field of the embedded bipole and the open field of the surrounding coronal hole. Previous numerical studies in Cartesian geometry, assuming uniform ambient magnetic field and plasma while neglecting gravity and solar wind, demonstrated that the model is robust and can produce jet-like events in simple configurations. We have extended these investigations by including spherical geometry,gravity, and solar wind in a nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that the jet is initiated by the onset of a kink-like instability of the internal closed field, which induces a burst of reconnection between the closed and external open field, launching a helical jet. Our new results demonstrate that the jet propagation is sustained through the outer corona, in the form of a traveling nonlinear Alfven wave front trailed by slower-moving plasma density enhancements that are compressed and accelerated by the wave. This finding agrees well with observations of white-light coronal-hole jets, and can explain microstreams and torsional Alfven waves detected in situ in the solar wind. We also use our numerical results to deduce scaling relationships between properties of the coronal source region and the characteristics of the resulting jet, which can be tested against observations. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840005037','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840005037">The average solar wind in the inner heliosphere: Structures and slow variations</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Schwenn, R. 1983-01-01 Measurements from the HELIOS solar probes indicated that apart from solar activity related disturbances there exist two states of the solar wind which might result from basic differences in the acceleration process: the fast solar wind (v 600 kms(-)1) emanating from magnetically open regions in the solar corona and the "slow" solar wind (v 400 kms(-)1) correlated with the more active regions and its mainly closed magnetic structures. In a comprehensive study using all HELIOS data taken between 1974 and 1982 the average behavior of the basic plasma parameters were analyzed as functions of the solar wind speed. The long term variations of the solar wind parameters along the solar cycle were also determined and numerical estimates given. These modulations appear to be distinct though only minor. In agreement with earlier studies it was concluded that the major modulations are in the number and size of high speed streams and in the number of interplanetary shock waves caused by coronal transients. The latter ones usually cause huge deviations from the averages of all parameters. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030022667','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030022667">Interplanetary Coronal Mass Ejections in the Near-Earth Solar Wind During 1996-2002</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Cane, H. V.; Richardson, I. G. 2003-01-01 We summarize the occurrence of interplanetary coronal mass injections (ICMEs) in the near-Earth solar wind during 1996-2002, corresponding to the increasing and maximum phases of solar cycle 23. In particular, we give a detailed list of such events. This list, based on in-situ observations, is not confined to subsets of ICMEs, such as magnetic clouds or those preceded by halo CMEs observed by the SOHO/LASCO coronagraph, and provides an overview of 214 ICMEs in the near-Earth solar wind during this period. The ICME rate increases by about an order of magnitude from solar minimum to solar maximum (when the rate is approximately 3 ICMEs/solar rotation period). The rate also shows a temporary reduction during 1999, and another brief, deeper reduction in late 2000-early 2001, which only approximately track variations in the solar 10 cm flux. In addition, there are occasional periods of several rotations duration when the ICME rate is enhanced in association with high solar activity levels. We find an indication of a periodic variation in the ICME rate, with a prominent period of approximately 165 days similar to that previously reported in various solar phenomena. It is found that the fraction of ICMEs that are magnetic clouds has a solar cycle variation, the fraction being larger near solar minimum. For the subset of events that we could associate with a CME at the Sun, the transit speeds from the Sun to the Earth were highest after solar maximum. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999AIPC..471..729D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999AIPC..471..729D">Real-time Kp predictions from ACE real time solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Detman, Thomas; Joselyn, Joann 1999-06-01 The Advanced Composition Explorer (ACE) spacecraft provides nearly continuous monitoring of solar wind plasma, magnetic fields, and energetic particles from the Sun-Earth L1 Lagrange point upstream of Earth in the solar wind. The Space Environment Center (SEC) in Boulder receives ACE telemetry from a group of international network of tracking stations. One-minute, and 1-hour averages of solar wind speed, density, temperature, and magnetic field components are posted on SEC's World Wide Web page within 3 to 5 minutes after they are measured. The ACE Real Time Solar Wind (RTSW) can be used to provide real-time warnings and short term forecasts of geomagnetic storms based on the (traditional) Kp index. Here, we use historical data to evaluate the performance of the first real-time Kp prediction algorithm to become operational. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JGRA..110.9S14R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JGRA..110.9S14R">Coronal mass ejection kinematics deduced from white light (Solar Mass Ejection Imager) and radio (Wind/WAVES) observations</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Reiner, M. J.; Jackson, B. V.; Webb, D. F.; Mizuno, D. R.; Kaiser, M. L.; Bougeret, J.-L. 2005-09-01 White-light and radio observations are combined to deduce the coronal and interplanetary kinematics of a fast coronal mass ejection (CME) that was ejected from the Sun at about 1700 UT on 2 November 2003. The CME, which was associated with an X8.3 solar flare from W56°, was observed by the Mauna Loa and Solar and Heliospheric Observatory (SOHO) Large-Angle Spectrometric Coronograph (LASCO) coronagraphs to 14 R⊙. The measured plane-of-sky speed of the LASCO CME was 2600 km s-1. To deduce the kinematics of this CME, we use the plane-of-sky white light observations from both the Solar Mass Ejection Imager (SMEI) all-sky camera on board the Coriolis spacecraft and the SOHO/LASCO coronagraph, as well as the frequency drift rate of the low-frequency radio data and the results of the radio direction-finding analysis from the WAVES experiment on the Wind spacecraft. In agreement with the in situ observations for this event, we find that both the white light and radio observations indicate that the CME must have decelerated significantly beginning near the Sun and continuing well into the interplanetary medium. More specifically, by requiring self-consistency of all the available remote and in situ data, together with a simple, but not unreasonable, assumption about the general characteristic of the CME deceleration, we were able to deduce the radial speed and distance time profiles for this CME as it propagated from the Sun to 1 AU. The technique presented here, which is applicable to mutual SMEI/WAVES CME events, is expected to provide a more complete description and better quantitative understanding of how CMEs propagate through interplanetary space, as well as how the radio emissions, generated by propagating CME/shocks, relate to the shock and CME. This understanding can potentially lead to more accurate predictions for the onset times of space weather events, such as those that were observed during this unique period of intense solar activity. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1911005K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1911005K">A General Identification of Instabilities in Solar Wind Plasma, and a Particular Application to the WIND Data Set.</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Klein, Kristopher; Kasper, Justin; Korreck, Kelly; Alterman, Benjamin 2017-04-01 The role of free-energy driven instabilities in governing heating and acceleration processes in the heliosphere has been studied for over half a century, with significant recent advancements enabled by the statistical analysis of decades worth of observations from missions such as WIND. Typical studies focus on marginal stability boundaries in a reduced parameter space, such as the canonical plasma beta versus temperature anisotropy plane, due to a single source of free energy. We present a more general method of determining stability, accounting for all possible sources of free energy in the constituent plasma velocity distributions. Through this novel implementation, we can efficiently determine if the plasma is linearly unstable, and if so, how many normal modes are growing. Such identification will enabling us to better pinpoint the dominant heating or acceleration processes in solar wind plasma. The theory behind this approach is reviewed, followed by a discussion of our methods for a robust numerical implementation, and an initial application to portions of the WIND data set. Further application of this method to velocity distribution measurements from current missions, including WIND, upcoming missions, including Solar Probe Plus and Solar Orbiter, and missions currently in preliminary phases, such as ESA's THOR and NASA's IMAP, will help elucidate how instabilities shape the evolution of the heliosphere. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917470P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917470P">Is tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control?</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Prikryl, Paul; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Bruntz, Robert; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel; Pastirčák, Vladimír 2017-04-01 More than four decades have passed since a link between solar wind magnetic sector boundary structure and mid-latitude upper tropospheric vorticity was discovered (Wilcox et al., Science, 180, 185-186, 1973). The link has been later confirmed and various physical mechanisms proposed but apart from controversy, little attention has been drawn to these results. To further emphasize their importance we investigate the occurrence of mid-latitude severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. It is observed that significant snowstorms, windstorms and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., Ann. Geophys., 27, 1-30, 2009; Prikryl et al., J. Atmos. Sol.-Terr. Phys., 149, 219-231, 2016) is corroborated for the southern hemisphere. A physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., Space Sci. Rev., 54, 297-375, 1990) show that propagating waves originating in the thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere thus initiating convection to form cloud/precipitation bands </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1167251','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1167251">Agua Caliente Wind/Solar Project at Whitewater Ranch</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hooks, Todd; Stewart, Royce 2014-12-16 Agua Caliente Band of Cahuilla Indians (ACBCI) was awarded a grant by the Department of Energy (DOE) to study the feasibility of a wind and/or solar renewable energy project at the Whitewater Ranch (WWR) property of ACBCI. Red Mountain Energy Partners (RMEP) was engaged to conduct the study. The ACBCI tribal lands in the Coachella Valley have very rich renewable energy resources. The tribe has undertaken several studies to more fully understand the options available to them if they were to move forward with one or more renewable energy projects. With respect to the resources, the WWR property clearly hasmore » excellent wind and solar resources. The DOE National Renewable Energy Laboratory (NREL) has continued to upgrade and refine their library of resource maps. The newer, more precise maps quantify the resources as among the best in the world. The wind and solar technology available for deployment is also being improved. Both are reducing their costs to the point of being at or below the costs of fossil fuels. Technologies for energy storage and microgrids are also improving quickly and present additional ways to increase the wind and/or solar energy retained for later use with the network management flexibility to provide power to the appropriate locations when needed. As a result, renewable resources continue to gain more market share. The transitioning to renewables as the major resources for power will take some time as the conversion is complex and can have negative impacts if not managed well. While the economics for wind and solar systems continue to improve, the robustness of the WWR site was validated by the repeated queries of developers to place wind and/or solar there. The robust resources and improving technologies portends toward WWR land as a renewable energy site. The business case, however, is not so clear, especially when the potential investment portfolio for ACBCI has several very beneficial and profitable alternatives.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1326049-solar-wind-possible-source-fast-temporal-variations-heliospheric-ribbon','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1326049-solar-wind-possible-source-fast-temporal-variations-heliospheric-ribbon">The solar wind as a possible source of fast temporal variations of the heliospheric ribbon</a> <a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a> Kucharek, H.; Fuselier, S. A.; Wurz, P.; ... 2013-10-04 Here we present a possible source of pickup ions (PUIs) the ribbon observed by the Interstellar Boundary EXplorer (IBEX). We suggest that a gyrating solar wind and PUIs in the ramp and in the near downstream region of the termination shock (TS) could provide a significant source of energetic neutral atoms (ENAs) in the ribbon. A fraction of the solar wind and PUIs are reflected and energized during the first contact with the TS. Some of the solar wind may be reflected propagating toward the Sun but most of the solar wind ions form a gyrating beam-like distribution that persistsmore » until it is fully thermalized further downstream. Depending on the strength of the shock, these gyrating distributions can exist for many gyration periods until they are scattered/thermalized due to wave-particle interactions at the TS and downstream in the heliosheath. During this time, ENAs can be produced by charge exchange of interstellar neutral atoms with the gyrating ions. In order to determine the flux of energetic ions, we estimate the solar wind flux at the TS using pressure estimates inferred from in situ measurements. Assuming an average path length in the radial direction of the order of a few AU before the distribution of gyrating ions is thermalized, one can explain a significant fraction of the intensity of ENAs in the ribbon observed by IBEX. In conclusion, with a localized source and such a short integration path, this model would also allow fast time variations of the ENA flux.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22340172-new-three-dimensional-solar-wind-model-spherical-coordinates-six-component-grid','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22340172-new-three-dimensional-solar-wind-model-spherical-coordinates-six-component-grid">A NEW THREE-DIMENSIONAL SOLAR WIND MODEL IN SPHERICAL COORDINATES WITH A SIX-COMPONENT GRID</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Feng, Xueshang; Zhang, Man; Zhou, Yufen, E-mail: fengx@spaceweather.ac.cn In this paper, we introduce a new three-dimensional magnetohydrodynamics numerical model to simulate the steady state ambient solar wind from the solar surface to 215 R {sub s} or beyond, and the model adopts a splitting finite-volume scheme based on a six-component grid system in spherical coordinates. By splitting the magnetohydrodynamics equations into a fluid part and a magnetic part, a finite volume method can be used for the fluid part and a constrained-transport method able to maintain the divergence-free constraint on the magnetic field can be used for the magnetic induction part. This new second-order model in space andmore » time is validated when modeling the large-scale structure of the solar wind. The numerical results for Carrington rotation 2064 show its ability to produce structured solar wind in agreement with observations.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SSRv..214...79S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SSRv..214...79S">Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sibeck, David G.; Allen, R.; Aryan, H.; Bodewits, D.; Brandt, P.; Branduardi-Raymont, G.; Brown, G.; Carter, J. A.; Collado-Vega, Y. M.; Collier, M. R.; Connor, H. K.; Cravens, T. E.; Ezoe, Y.; Fok, M.-C.; Galeazzi, M.; Gutynska, O.; Holmström, M.; Hsieh, S.-Y.; Ishikawa, K.; Koutroumpa, D.; Kuntz, K. D.; Leutenegger, M.; Miyoshi, Y.; Porter, F. S.; Purucker, M. E.; Read, A. M.; Raeder, J.; Robertson, I. P.; Samsonov, A. A.; Sembay, S.; Snowden, S. L.; Thomas, N. E.; von Steiger, R.; Walsh, B. M.; Wing, S. 2018-06-01 Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in context by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the Kelvin-Helmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time- and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SSRv..212.1453F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SSRv..212.1453F">Solar Wind Interaction and Impact on the Venus Atmosphere</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Futaana, Yoshifumi; Stenberg Wieser, Gabriella; Barabash, Stas; Luhmann, Janet G. 2017-11-01 Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years. Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models </li> <li> <a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720044025&hterms=Parkin&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DParkin','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720044025&hterms=Parkin&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DParkin">Measurements of lunar magnetic field interaction with the solar wind.</a> <a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Dyal, P.; Parkin, C. W.; Snyder, C. W.; Clay, D. R. 1972-01-01 Study of the compression of the remanent lunar magnetic field by the solar wind, based on measurements of remanent magnetic fields at four Apollo landing sites and of the solar wind at two of these sites. Available data show that the remanent magnetic field at the lunar surface is compressed as much as 40% above its initial value by the solar wind, but the total remanent magnetic pressure is less than the stagnation pressure by a factor of six, implying that a local shock is not formed. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1611574T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1611574T">Spectral analysis of the solar wind turbulence in the vicinity of Venus</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Teodorescu, Eliza; Echim, Marius; Munteanu, Costel; Voitcu, Gabriel; Zhang, Tielong; Barabash, Stanislav; Budnik, Elena; Fedorov, Andrei 2014-05-01 In this study we analyze magnetic field data provided by Venus Express (VEX) between 2007 and 2008. During each of the probe's eccentric polar orbit around Venus, VEX performs plasma and magnetic field measurements in the environment around the planet both in Venus induced magnetosphere and in the solar wind at several tens of thousands of kilometers away from the magnetosphere. This latter data set has a unique scientific value as it provides observations of magnetic turbulence in the solar wind around 0.72 AU, in the vicinity of Venus. We discuss a semi-automated method to select solar wind magnetic field data at 1 Hz from Venus Express Magnetometer (MAG) data by using plasma data from the Analyser of Space Plasma and Energetic Atoms (ASPERA). The time intervals when VEX is in the solar wind are automatically determined for 2007 and 2008. We apply a Fourier transform on the selected data and calculate the power spectral densities (PSD) of the turbulent magnetic field through Welch's algorithm. We compute the PSD of the three components of the magnetic field for the time intervals when both MAG and ASPERA were operating in the solar wind, for each VEX orbit between 1st of January 2007 and 31st of December 2008. The data base includes a number of 374 individual spectra. We discuss the spectral properties of turbulence and illustrate similarities between fast and slow wind during the minimum phase of the solar cycle for each of VEX's orbit which satisfies the selection criteria for a period of two years. Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418. Data analysis was done with the AMDA science analysis system provided by the Centre de Données de la Physique des Plasmas (IRAP, Université Paul Sabatier, Toulouse) supported by CNRS and CNES. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913659E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913659E">Mars atmospheric losses induced by the solar wind: current knowledge and perspective</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ermakov, Vladimir; Zelenyi, Lev; Vaisberg, Oleg; Sementsov, Egor; Dubinin, Eduard 2017-04-01 Solar wind induced atmospheric losses have been studied since earlier 1970th. Several loss channels have been identified including pick-up of exospheric photo-ions and ionospheric ions escape. Measurements performed during several solar cycles showed variation of these losses by about factor of 10, being largest at maximum solar activity. MAVEN spacecraft equipped with comprehensive set of instruments with high temporal and mass resolution operating at Mars since fall 2014 ensures much better investigation of solar wind enforcing Martian environment, Mars atmospheric losses processes and mass loss rate. These issues are very important for understanding of Martian atmospheric evolution including water loss during cosmogonic time. Simultaneous observations by MAVEN and MEX spacecraft open the new perspective in study of Martian environment. In this report we discuss results of past and current missions and preliminary analysis of heavy ions escape using simultaneous measurements of MEX and MAVEN spacecraft. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH33A2765H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH33A2765H">Kinetic Theory and Fast Wind Observations of the Electron Strahl</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Horaites, K.; Boldyrev, S.; Wilson, L. B., III; Figueroa-Vinas, A.; Merka, J. 2017-12-01 We develop a model for the strahl population in the solar wind - a narrow, low-density and high-energy electron beam centered on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances where the plasma density, temperature, and the strength of the magnetic field decline as power-laws of the distance along a magnetic flux tube. Our solution for the strahl depends on a number of parameters that, in the absence of the analytic solution for the full electron velocity distribution function (eVDF), cannot be derived from the theory. We however demonstrate that these parameters can be efficiently found from matching our solution with the observations. To this end, we compare our model with the eVDF measured by the Wind satellite's SWE strahl detector. The model is successful at predicting the angular width (FWHM) of the strahl for the Wind data at 1 AU, in particular by predicting how this width scales with particle energy and background density. We find the shape of the strahl distribution is largely determined by the local temperature Knudsen number γ |T dT/dx|/n, which parametrizes solar wind collisionality. We compute averaged strahl distributions for typical Knudsen numbers observed in the solar wind, and fit our model to these data. The model can be matched quite closely to the eVDFs at 1 AU; however, it then overestimates the strahl amplitude compared to the amplitude of the electron core at larger heliocentric distances. This indicates that our model may need to be improved through the inclusion of additional physics, possibly through the introduction of "anomalous diffusion" of the strahl electrons. </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......125T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......125T">Effect of coherent structures on energetic particle intensity in the solar wind</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tessein, Jeffrey A. Solar energetic particles in the solar wind are accelerated in both solar flares and shocks assocated with fast coronal mass ejections. They follow the interplanetary magnetic field and, upon reaching Earth, have implications for space weather. Space weather affects astronaut health and orbiting equipment through radiation hazard and electrical infrastructure on the ground with ground induced currents. Economic im- pacts include disruption of GPS and redirection of commercial polar flights due to a dangerous radiation environment over the poles. By studying how these particles interact with the magnetic fields we can better predict onset times and diffusion of these events. We find, using superposed epoch analysis and conditional statisitics from spacecraft observations that there is a strong association between energetic particles in the solar wind and magnetic discontinuities. This may be related to turbulent dissipa- tion mechanisms in which coherent structures in the solar wind seem to be preferred sites of heating, plasma instabilites and dissipation. In the case of energetic particles, magnetic reconnection and transport in flux tubes are likely to play a role. Though we focus on data away from large shocks, trapping can occur in the downstream region of shocks due to the preponderance of compressive turbulence in these areas. This thesis lays the ground work for the results described above with an intro- duction to solar wind and heliospheric physics in Chapter 1. Chapter 2 is an intro- duction to the acceleration mechanisms that give rise to observed energetic particle events. Chapter 3 describes various data analysis techniques and statistics that are bread and butter when analyzing spacecraft data for turbulence and energetic particle studies. Chapter 4 is a digression that covers preliminary studies that were done on the side; scale dependent kurtosis, ergodic studies and initial conditions for simulations. Chapter 5 contains that central published </li> <li> <a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22034600-evidence-polar-ray-jets-sources-microstream-peaks-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22034600-evidence-polar-ray-jets-sources-microstream-peaks-solar-wind">EVIDENCE FOR POLAR X-RAY JETS AS SOURCES OF MICROSTREAM PEAKS IN THE SOLAR WIND</a> <a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Neugebauer, Marcia, E-mail: mneugeb@lpl.arizona.edu 2012-05-01 It is proposed that the interplanetary manifestations of X-ray jets observed in solar polar coronal holes during periods of low solar activity are the peaks of the so-called microstreams observed in the fast polar solar wind. These microstreams exhibit velocity fluctuations of {+-}35 km s{sup -1}, higher kinetic temperatures, slightly higher proton fluxes, and slightly higher abundances of the low-first-ionization-potential element iron relative to oxygen ions than the average polar wind. Those properties can all be explained if the fast microstreams result from the magnetic reconnection of bright-point loops, which leads to X-ray jets which, in turn, result in solarmore » polar plumes. Because most of the microstream peaks are bounded by discontinuities of solar origin, jets are favored over plumes for the majority of the microstream peaks.« less </li> <li> <a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.3900L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.3900L">Saptio-temporal complementarity of wind and solar power in India</a> <a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lolla, Savita; Baidya Roy, Somnath; Chowdhury, Sourangshu 2015-04-01 Wind and solar power are likely to be a part of the solution to the climate change problem. That is why they feature prominently in the energy policies of all industrial economies including India. One of the major hindrances that is preventing an explosive growth of wind and solar energy is the issue of intermittency. This is a major problem because in a rapidly moving economy, energy production must match the patterns of energy demand. Moreover, sudden increase and decrease in energy supply may destabilize the power grids leading to disruptions in power supply. In this work we explore if the patterns of variability in wind and solar energy availability can offset each other so that a constant supply can be guaranteed. As a first step, this work focuses on seasonal-scale variability for each of the 5 regional power transmission grids in India. Communication within each grid is better than communication between grids. Hence, it is assumed that the grids can switch sources relatively easily. Wind and solar resources are estimated using the MERRA Reanalysis data for the 1979-2013 period. Solar resources are calculated with a 20% conversion efficiency. Wind resources are estimated using a 2 MW turbine power curve. Total resources are obtained by optimizing location and number of wind/solar energy farms. Preliminary results show that the southern and western grids are more appropriate for cogeneration than the other grids. Many studies on wind-solar cogeneration have focused on temporal complementarity at local scale. However, this is one of the first studies to explore spatial complementarity over regional scales. This project may help accelerate renewable energy penetration in India by identifying regional grid(s) where the renewable energy intermittency problem can be minimized. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active">25</li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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Sample records for observed solar wind