The solar wind - Moon interaction discovered by MAP-PACE on KAGUYA

NASA Astrophysics Data System (ADS)

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 Moon. When KAGUYA flew over South Pole Aitken region, where strong magnetic anomalies exist, solar wind ions reflected by magnetic anomalies were observed. These reflected ions had nearly the same energy as the incident solar wind ions, and their flux was more than 10% of the incident solar wind ions. At 100km altitude, when the reflected ions were observed, the simultaneously measured electrons were often heated and the incident solar wind ions were sometimes slightly decelerated. At ~50km altitude, when the reflected ions were observed, proton scattering at the lunar surface clearly disappeared. At ~10km altitude, the interaction between the solar wind ions and the lunar magnetic anomalies was remarkable with clear deceleration of the incident solar wind ions and heating of the reflected ions as well as significant heating of the electrons. These newly discovered plasma signatures around the Moon are the evidences of the smallest magnetosphere ever observed.

Does the magnetic expansion factor play a role in solar wind acceleration?

NASA Astrophysics Data System (ADS)

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 studies of solar wind originating from pseudostreamers (Riley et al., 2015, Riley & Luhmann 2012) and will contribute to identifying the physical properties of solar wind from these regions. Future work will explore the role of fs in modulating the fast solar wind and will involve a similar analysis for cases where spacecraft are deep within coronal holes.

On the origins of energetic ions in the earth's dayside magnetosheath

NASA Technical Reports Server (NTRS)

Fuselier, S. A.; Klumpar, D. M.; Shelley, E. G.

1991-01-01

Energetic ion events in the earth's dayside subsolar magnetosheath (0900 - 1300 Local Time) are surveyed using data from the AMPTE/CCE Hot Plasma Composition Experiment. Ion species carrying the signature of their origin O(+) and energetic He(2+) are used to distinguish between magnetospheric and solar wind origins for the energetic ion events. The results of this survey indicate that the majority of energetic (10-17 keV/e) H(+) and He(2+) ions observed in the dayside magnetosheath are accelerated from the solar wind population. The energetic He(2+) to H(+) density ratio in the magnetosheath is consistent with that predicted from first-order Fermi acceleration of solar wind ions in the turbulent regions upstream and downstream from the earth's quasi-parallel bow shock. The simultaneous occurrence of both energetic He(2+) and magnetospheric O(+) indicates that, on occasion, both Fermi acceleration of solar wind ions and leakage of magnetospheric ions occurs in the dayside magnetosheath.

Variations of Strahl Properties with Fast and Slow Solar Wind

NASA Technical Reports Server (NTRS)

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

2008-01-01

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

Heavy ion composition in the inner heliosphere: Predictions for Solar Orbiter

NASA Astrophysics Data System (ADS)

Lepri, S. T.; Livi, S. A.; Galvin, A. B.; Kistler, L. M.; Raines, J. M.; Allegrini, F.; Collier, M. R.; Zurbuchen, T.

2014-12-01

The Heavy Ion Sensor (HIS) on SO, with its high time resolution, will provide the first ever solar wind and surpathermal heavy ion composition and 3D velocity distribution function measurements inside the orbit of Mercury. These measurements will provide us the most in depth examination of the origin, structure and evolution of the solar wind. The near co-rotation phases of the orbiter will enable the most accurate mapping of in-situ structures back to their solar sources. Measurements of solar wind composition and heavy ion kinetic properties enable characterization of the sources, transport mechanisms and acceleration processes of the solar wind. This presentation will focus on the current state of in-situ studies of heavy ions in the solar wind and their implications for the sources of the solar wind, the nature of structure and variability in the solar wind, and the acceleration of particles. Additionally, we will also discuss opportunities for coordinated measurements across the payloads of Solar Orbiter and Solar Probe in order to answer key outstanding science questions of central interest to the Solar and Heliophysics communities.

Validating a magnetic reconnection model for the magnetopause

NASA Astrophysics Data System (ADS)

Schultz, Colin

2012-01-01

Originating in the Sun's million-degree corona, the solar wind flows at supersonic speeds into interplanetary space, carrying with it the solar magnetic field. As the solar wind reaches Earth's orbit, its interaction with the geomagnetic field forms the magnetosphere, a bubble-like structure within the solar wind flow that shields Earth from direct exposure to the solar wind as well as to the highly energetic charged particles produced during solar storms. Under certain orientations, the magnetic field entrained in the solar wind, known as the interplanetary magnetic field (IMF), merges with the geomagnetic field, transferring mass, momentum, and energy to the magnetosphere. The merging of these two distinct magnetic fields occurs through magnetic reconnection, a fundamental plasma-physical process that converts magnetic energy into kinetic energy and heat.

A study of the relationship between micropulsations and solar wind properties

NASA Technical Reports Server (NTRS)

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.

A New View of the Origin of the Solar Wind

NASA Technical Reports Server (NTRS)

Woo, Richard; Habbal, Shadia Rifai

1999-01-01

This paper uses white-light measurements made by the SOHO LASCO coronagraph and HAO Mauna Loa Mk III K-coronameter to illustrate the new view of solar wind structure deduced originally from radio occultation measurements. It is shown that the density profile closest to the Sun at 1.15 Ro, representing the imprint of the Sun, is carried essentially radially into interplanetary space by small-scale raylike structures that permeate the solar corona and which have only been observed by radio occultation measurements. The only exception is the small volume of interplanetary space occupied by the heliospheric plasma sheet that evolves from coronal streamers within a few solar radii of the Sun. The radial preservation of the density profile also implies that a significant fraction of field lines which extend into interplanetary space originate from the quiet Sun, and are indistinguishable in character from those emanating from polar coronal holes. The white-light measurements dispel the long-held belief that the boundaries of polar coronal holes diverge significantly, and further support the view originally proposed that the fast solar wind originates from the quiet Sun as well as polar coronal holes.

Auroral bright spot in Jupiter’s active region in corresponding to solar wind dynamic

NASA Astrophysics Data System (ADS)

Haewsantati, K.; Wannawichian, S.; Clarke, J. T.; Nichols, J. D.

2017-09-01

Jupiter’s polar emission has brightness whose behavior appears to be unstable. This work focuses on the bright spot in active region which is a section of Jupiter’s polar emission. Images of the aurora were taken by Advanced Camera for Surveys (ACS) onboard the Hubble Space Telescope (HST). Previously, two bright spots, which were found on 13 th May 2007, were suggested to be fixed on locations described by system III longitude. The bright spot’s origin in equatorial plane was proposed to be at distance 80-90 Jovian radii and probably associated with the solar wind properties. This study analyzes additional data on May 2007 to study long-term variation of brightness and locations of bright spots. The newly modified magnetosphere-ionosphere mapping based on VIP4 and VIPAL model is used to locate the origin of bright spot in magnetosphere. Furthermore, the Michigan Solar Wind Model or mSWiM is also used to study the variation of solar wind dynamic pressure during the time of bright spot’s observation. We found that the bright spots appear in similar locations which correspond to similar origins in magnetosphere. In addition, the solar wind dynamic pressure should probably affect the bright spot’s variation.

Periodic Alpha Signatures and the Origins of the Slow Solar Wind

NASA Astrophysics Data System (ADS)

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 structures seem to support the S-web model over the expansion factor model and can provide additional constrains to slow solar wind models moving forward.

Nature and Variability of Coronal Streamers and their Relationship to the Slow Speed Wind

NASA Technical Reports Server (NTRS)

Strachan, Leonard

2005-01-01

NASA Grant NAG5-12781 is a study on the "Nature and Variability of Coronal Streamers and their Relationship to the Slow Speed Wind." The two main goals of this study are to identify: 1) Where in the streamer structure does the solar wind originate, and 2) What coronal conditions are responsible for the variability of the slow speed wind. To answer the first question, we examined the mostly closed magnetic field regions in streamer cores to search for evidence of outflow. Preliminary results from the OVI Doppler dimming ratios indicates that most of the flow originates from the edges of coronal streamers but this idea should be confirmed by a comparison of the coronal plasma properties with in situ solar wind data. To answer the second question, the work performed thus far suggests that solar minimum streamers have larger perpendicular velocity distributions than do solar maximum streamers. If it can be shown that solar minimum streamers also produce higher solar wind speeds then this would suggest that streamers and coronal holes have similar solar wind acceleration mechanisms. The key to both questions lie in the analysis of the in situ solar wind data sets. This work was not able to be completed during the period of performance and therefore the grant was formally extended for an additional year at no cost to NASA. We hope to have final results and a publication by the end of the calendar year 2004. The SAO personnel involved in the research are Leonard Strachan (PI), Mari Paz Miralles, Alexander Panasyuk, and a Southern University student Michael Baham.

The structure of the solar wind in the inner heliosphere

NASA Astrophysics Data System (ADS)

Lee, Christina On-Yee

2010-12-01

This dissertation is devoted to expanding our understanding of the solar wind structure in the inner heliosphere and variations therein with solar activity. Using spacecraft observations and numerical models, the origins of the large-scale structures and long-term trends of the solar wind are explored in order to gain insights on how our Sun determines the space environments of the terrestrial planets. I use long term measurements of the solar wind density, velocity, interplanetary magnetic field, and particles, together with models based on solar magnetic field data, to generate time series of these properties that span one solar rotation (˜27 days). From these time series, I assemble and obtain the synoptic overviews of the solar wind properties. The resulting synoptic overviews show that the solar wind around Mercury, Venus, Earth, and Mars is a complex co-rotating structure with recurring features and occasional transients. During quiet solar conditions, the heliospheric current sheet, which separates the positive interplanetary magnetic field from the negative, usually has a remarkably steady two- or four-sector structure that persists for many solar rotations. Within the sector boundaries are the slow and fast speed solar wind streams that originate from the open coronal magnetic field sources that map to the ecliptic. At the sector boundaries, compressed high-density and the related high-dynamic pressure ridges form where streams from different coronal source regions interact. High fluxes of energetic particles also occur at the boundaries, and are seen most prominently during the quiet solar period. The existence of these recurring features depends on how long-lived are their source regions. In the last decade, 3D numerical solar wind models have become more widely available. They provide important scientific tools for obtaining a more global view of the inner heliosphere and of the relationships between conditions at Mercury, Venus, Earth, and Mars. When I compare the model results with observations for periods outside of solar wind disturbances, I find that the models do a good job of simulating at least the steady, large-scale, ambient solar wind structure. However, it remains a challenge to accurately model the solar wind during active solar conditions. During these times, solar transients such as coronal mass ejections travel through interplanetary space and disturb the ambient solar wind, producing a far less predictable and modelable space environment. However, such conditions may have the greatest impact on the planets - especially on their atmospheres and magnetospheres. I therefore also consider the next steps in modeling, toward including active conditions.

Common origin of kinetic scale turbulence and the electron halo in the solar wind – Connection to nanoflares

DOE Office of Scientific and Technical Information (OSTI.GOV)

Che, Haihong; Goddard Space Flight Center, NASA, Greenbelt, MD, 20771

2016-03-25

We summarize our recent studies on the origin of solar wind kinetic scale turbulence and electron halo in the electron velocity distribution function. Increasing observations of nanoflares and microscopic type III radio bursts strongly suggest that nanoflares and accelerated electron beams are common in the corona. Based on particle-in-cell simulations, we show that both the core-halo feature and kinetic scale turbulence observed in the solar wind can be produced by the nonlinear evolution of electron two-stream instability driven by nanoflare accelerated electron beams. The energy exchange between waves and particles reaches equilibrium in the inner corona and the key featuresmore » of the turbulence and velocity distribution are preserved as the solar wind escapes into interplanetary space along open magnetic field lines. Observational tests of the model and future theoretical work are discussed.« less

Do In Situ Observations Contain Signatures of Intermittent Fast Solar Wind Acceleration?

NASA Astrophysics Data System (ADS)

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.

Topological Origins of the Slow Solar Wind

NASA Technical Reports Server (NTRS)

Antiochos, Spiro

2008-01-01

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

High coronal structure of high velocity solar wind stream sources

NASA Technical Reports Server (NTRS)

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.

Discovery of Suprathermal Ionospheric Origin Fe+ in and Near Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Christon, S. P.; Hamilton, D. C.; Plane, J. M. C.; Mitchell, D. G.; Grebowsky, J. M.; Spjeldvik, W. N.; Nylund, S. R.

2017-11-01

Suprathermal (87-212 keV/e) singly charged iron, Fe+, has been discovered in and near Earth's 9-30 RE equatorial magnetosphere using 21 years of Geotail STICS (suprathermal ion composition spectrometer) data. Its detection is enhanced during higher geomagnetic and solar activity levels. Fe+, rare compared to dominant suprathermal solar wind and ionospheric origin heavy ions, might derive from one or all three candidate lower-energy sources: (a) ionospheric outflow of Fe+ escaped from ion layers near 100 km altitude, (b) charge exchange of nominal solar wind iron, Fe+≥7, in Earth's exosphere, or (c) inner source pickup Fe+ carried by the solar wind, likely formed by solar wind Fe interaction with near-Sun interplanetary dust particles. Earth's semipermanent ionospheric Fe+ layers derive from tons of interplanetary dust particles entering Earth's atmosphere daily, and Fe+ scattered from these layers is observed up to 1000 km altitude, likely escaping in strong ionospheric outflows. Using 26% of STICS's magnetosphere-dominated data when possible Fe+2 ions are not masked by other ions, we demonstrate that solar wind Fe charge exchange secondaries are not an obvious Fe+ source. Contemporaneous Earth flyby and cruise data from charge-energy-mass spectrometer on the Cassini spacecraft, a functionally identical instrument, show that inner source pickup Fe+ is likely not important at suprathermal energies. Consequently, we suggest that ionospheric Fe+ constitutes at least a significant portion of Earth's suprathermal Fe+, comparable to the situation at Saturn where suprathermal Fe+ is also likely of ionospheric origin.

Escape for the Slow Solar Wind

NASA Astrophysics Data System (ADS)

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 that marks the edges of coronal holes and extends outward as the heliospheric current sheet are caused by supergranule-like convective flows. These motions drive magnetic reconnection that funnel plasma from the closed-field region onto enormous arcs that extend far away from the heliospheric current sheet, spanning tens of degrees in latitude and longitude.The simulations by Higginson and collaborators demonstrate that closed-field plasma from coronal-hole boundaries can be successfully channeled into the solar system. Due to the geometry and dynamics of the coronal holes, the plasma can travel far from the heliospheric current sheet, resulting in a slow solar wind of closed-field plasma consistent with our observations. These simulations therefore suggest aprocessthat resolves the long-standing puzzle of the slow solar wind.BonusCheck out the animation below, made from the results of the teams simulations. This video shows the location of a forming heliospheric arc at a distance of 12 solar radii. The arc forms as magnetic field lines at the boundary of a coronal hole change from closed to open, allowing closed-field flux to escape along them.http://aasnova.org/wp-content/uploads/2017/05/apjlaa6d72f4_video.mp4CitationA. K. Higginson et al 2017 ApJL 840 L10. doi:10.3847/2041-8213/aa6d72

Near-Earth Solar Wind Flows and Related Geomagnetic Activity During more than Four Solar Cycles (1963-2011)

NASA Technical Reports Server (NTRS)

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.

Foreshock and magnetosheath transients, origin and connection to the magnetopause.

NASA Astrophysics Data System (ADS)

Blanco-Cano, X.

2014-12-01

The solar wind interaction with earths's magnetosphere begins well ahead of the magnetopause when the solar wind encounters the foreshock, bow shock and magnetosheath. In these regions a variety of waves and magnetic structures exist and modify the solar wind. The foreshock is permeated by a variety of ultra low frequency (ULF) waves and magnetic transient structures such as shocklets, SLAMs, and cavitons. These structures are very compressive and are generated by the solar wind interaction with backstreaming particles plus non linear processes. Other structures such as hot flow anomalies (HFA), and spontaneous hot flow anomalies (SHFA) can also exist in the foreshock. HFAs are generated by discontinuities that arrive to the bow shock. Recent studies show that SHFA have the same profiles as HFA, but form by the interaction of foreshock cavitons with the bowshock. Foreshock bubbles can form when energetic ions upstream of the quasi-parallel bow shock interact with rotational discontinuities in the solar wind. All these structures can merge with the bow shock and be convected into the magnetosheath. The magnetosheath is both a place for rich plasma physical processes and a filter between solar wind and the magnetospheric plasma and magnetic field environments. It is permeated by the superposition of upstream convected structures plus locally generated waves (ion cyclotron and mirror mode). Recent studies have shown that jets and magnetosheath filamentary structures (MFS) can be observed downstream from the bow shock. Jets are associated to shock rippling efects and MFS to acceleration of particles at and near the shock. Due to the presence of the foreshock, bow shock and magnetosheath transients, the solar wind arriving to the magnetopause is very different to the pristine solar wind. In this talk we will address the main characteristics of these transients, discuss their origin, and how they can modify the solar wind, the bow shock, the magnetosheath and the magnetopause.

A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

PubMed

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.

The coherent relation between the solar wind proton speed and O{sup 7+}/O{sup 6+} ratio and its coronal sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, L., E-mail: lzh@umich.edu; Landi, E.; Fisk, L. A.

We analyze the two-hour resolution solar wind proton speed (V{sub p}) and charge state ratio of O{sup 7+}/O{sup 6+} measured by ACE (SWICS and SWEPAM) from 1998 to 2011 at 1 AU. By applying a two-step mapping method, we link the solar wind in-situ observations to the corona images captured by SOHO and STEREO, in which we identify the different plasma structures, such as active regions (ARs), coronal holes (CHs) and quiet Sun regions (QS), using a classification scheme based on pixel brightness. Then we determine from which region in the corona the solar wind originates. We examine the in-situmore » properties of the solar wind streams associated with CHs, ARs and QS regions. We find that more than half of CH associated wind is actually slow wind, and O{sup 7+}/O{sup 6+} ratio has a strong coherent correlation with the location of the solar wind coronal sources. Therefore, we conclude that O{sup 7+}/O{sup 6+} ratio can be used as a much more effective discriminator to identify solar wind coronal sources region than V{sub p}.« less

Composition of Coronal Mass Ejections

NASA Technical Reports Server (NTRS)

Zurbuchen, T. H.; Weberg, M.; von Steiger, R.; Mewaldt, R. A.; Lepri, S. T.; Antiochos, S. K.

2016-01-01

We analyze the physical origin of plasmas that are ejected from the solar corona. To address this issue, we perform a comprehensive analysis of the elemental composition of interplanetary coronal mass ejections (ICMEs) using recently released elemental composition data for Fe, Mg, Si, S, C, N, Ne, and He as compared to O and H. We find that ICMEs exhibit a systematic abundance increase of elements with first ionization potential (FIP) less than 10 electronvolts, as well as a significant increase of Ne as compared to quasi-stationary solar wind. ICME plasmas have a stronger FIP effect than slow wind, which indicates either that an FIP process is active during the ICME ejection or that a different type of solar plasma is injected into ICMEs. The observed FIP fractionation is largest during times when the Fe ionic charge states are elevated above Q (sub Fe) is greater than 12.0. For ICMEs with elevated charge states, the FIP effect is enhanced by 70 percent over that of the slow wind. We argue that the compositionally hot parts of ICMEs are active region loops that do not normally have access to the heliosphere through the processes that give rise to solar wind. We also discuss the implications of this result for solar energetic particles accelerated during solar eruptions and for the origin of the slow wind itself.

Composition of Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Zurbuchen, T. H.; Weberg, M.; von Steiger, R.; Mewaldt, R. A.; Lepri, S. T.; Antiochos, S. K.

2016-07-01

We analyze the physical origin of plasmas that are ejected from the solar corona. To address this issue, we perform a comprehensive analysis of the elemental composition of interplanetary coronal mass ejections (ICMEs) using recently released elemental composition data for Fe, Mg, Si, S, C, N, Ne, and He as compared to O and H. We find that ICMEs exhibit a systematic abundance increase of elements with first ionization potential (FIP) < 10 eV, as well as a significant increase of Ne as compared to quasi-stationary solar wind. ICME plasmas have a stronger FIP effect than slow wind, which indicates either that an FIP process is active during the ICME ejection or that a different type of solar plasma is injected into ICMEs. The observed FIP fractionation is largest during times when the Fe ionic charge states are elevated above Q Fe > 12.0. For ICMEs with elevated charge states, the FIP effect is enhanced by 70% over that of the slow wind. We argue that the compositionally hot parts of ICMEs are active region loops that do not normally have access to the heliosphere through the processes that give rise to solar wind. We also discuss the implications of this result for solar energetic particles accelerated during solar eruptions and for the origin of the slow wind itself.

Sputtering by the Solar Wind: Effects of Variable Composition

NASA Technical Reports Server (NTRS)

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

2011-01-01

It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that there is no increase in the sputtering yield caused by highly charged heavy ions for metallic and for semiconducting surfaces, but the sputter yield can be noticeably increased in the case of a good insulating surface. Recently measurements of the solar wind composition have become available. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. Whereas many previous calculations of sputtering were limited to the effects of proton bombardment. we show that the heavy ion component. especially the He++ component. can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. We will discuss sputtering of both neutrals and ions.

Interplanetary ions during an energetic storm particle event - The distribution function from solar wind thermal energies to 1.6 MeV

NASA Technical Reports Server (NTRS)

Gosling, J. T.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Zwickl, R. D.; Paschmann, G.; Sckopke, N.; Hynds, R. J.

1981-01-01

An ion velocity distribution function of the postshock phase of an energetic storm particle (ESP) event is obtained from data from the ISEE 2 and ISEE 3 experiments. The distribution function is roughly isotropic in the solar wind frame from solar wind thermal energies to 1.6 MeV. The ESP event studied (8/27/78) is superposed upon a more energetic particle event which was predominantly field-aligned and which was probably of solar origin. The observations suggest that the ESP population is accelerated directly out of the solar wind thermal population or its quiescent suprathermal tail by a stochastic process associated with shock wave disturbance. The acceleration mechanism is sufficiently efficient so that approximately 1% of the solar wind population is accelerated to suprathermal energies. These suprathermal particles have an energy density of approximately 290 eV cubic centimeters.

A Model for the Sources of the Slow Solar Wind

NASA Astrophysics Data System (ADS)

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.

Spectral features of solar plasma flows

NASA Astrophysics Data System (ADS)

Barkhatov, N. A.; Revunov, S. E.

2014-11-01

Research to the identification of plasma flows in the Solar wind by spectral characteristics of solar plasma flows in the range of magnetohydrodynamics is devoted. To do this, the wavelet skeleton pattern of Solar wind parameters recorded on Earth orbit by patrol spacecraft and then executed their neural network classification differentiated by bandwidths is carry out. This analysis of spectral features of Solar plasma flows in the form of magnetic clouds (MC), corotating interaction regions (CIR), shock waves (Shocks) and highspeed streams from coronal holes (HSS) was made. The proposed data processing and the original correlation-spectral method for processing information about the Solar wind flows for further classification as online monitoring of near space can be used. This approach will allow on early stages in the Solar wind flow detect geoeffective structure to predict global geomagnetic disturbances.

Constraints on the nature of the ancient lunar magnetic field

NASA Technical Reports Server (NTRS)

Goswami, J. N.

1976-01-01

Assuming that the physical properties of solar-wind ions have remained unchanged over the past 4 billion years, the observation of solar-wind ions in lunar breccias with compaction ages greater than 3.2 billion years places constraints on the nature and origin of the ancient lunar magnetic field. Solar-wind ions would not be expected to occur in old lunar breccias if a surface magnetic field of more than 0.03 gauss was present. Several explanations of this phenomenon are consistent with the global lunar dynamo theory of the origin of the lunar dipole field, including a wandering of the lunar dipole axis, late onset of dynamo action, and reversals of the lunar dipole field, producing a long-term field close to zero. Models invoking external field magnetization as the cause of the ancient lunar magnetic field constrain the dipole axis, precluding field reversals, and do not provide an alternative explanation for the observed occurrence of solar-wind ions in lunar breccias.

Solar Wind Eight: Proceedings of the Eighth International Solar Wind Conference. Proceedings

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Factors Controlling the Position of the Martian Magnetic Pileup Boundary

NASA Technical Reports Server (NTRS)

Crider, D. H.; Acuna, M.; Vignes, D.; Krymskii, A.; Breus, T.; Ness, N.

2003-01-01

The magnetic pileup boundary (MPB) at Mars is the position where the dominant ion of the plasma changes from solar wind protons to heavy ions of planetary origin. As such, it is the obstacle to solar wind ions. We investigate the factors that influence the shape and position of the magnetic pileup boundary at Mars in order to better understand the Martian obstacle to the solar wind. Employing MGS data, we determine how the Martian MPB moves in response to factors including solar wind pressure and crustal magnetic fields. We also study the factors affecting the thickness of the MPB. Further, we compare the magnetic pileup boundary to the magnetic barrier at Venus. Direct comparison aids in our interpretation of the physics involved in the solar wind interaction with planets lacking a significant intrinsic magnetic field.

Solar Illumination Control of the Polar Wind

NASA Astrophysics Data System (ADS)

Maes, L.; Maggiolo, R.; De 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.

The Formation of CIRs at Stream-Stream Interfaces and Resultant Geomagnetic Activity

NASA Technical Reports Server (NTRS)

Richardson, I. G.

2005-01-01

Corotating interaction regions (CIRs) are regions of compressed plasma formed at the leading edges of corotating high-speed solar wind streams originating in coronal holes as they interact with the preceding slow solar wind. Although particularly prominent features of the solar wind during the declining and minimum phases of the 11-year solar cycle, they may also be present at times of higher solar activity. We describe how CIRs are formed, and their geomagnetic effects, which principally result from brief southward interplanetary magnetic field excursions associated with Alfven waves. Seasonal and long-term variations in these effects are briefly discussed.

The "FIP Effect" and the Origins of Solar Energetic Particles and of the Solar Wind

NASA Astrophysics Data System (ADS)

Reames, Donald V.

2018-03-01

We find that the element abundances in solar energetic particles (SEPs) and in the slow solar wind (SSW), relative to those in the photosphere, show different patterns as a function of the first ionization potential (FIP) of the elements. Generally, the SEP and SSW abundances reflect abundance samples of the solar corona, where low-FIP elements, ionized in the chromosphere, are more efficiently conveyed upward to the corona than high-FIP elements that are initially neutral atoms. Abundances of the elements, especially C, P, and S, show a crossover from low to high FIP at {≈} 10 eV in the SEPs but {≈} 14 eV for the solar wind. Naively, this seems to suggest cooler plasma from sunspots beneath active regions. More likely, if the ponderomotive force of Alfvén waves preferentially conveys low-FIP ions into the corona, the source plasma that eventually will be shock-accelerated as SEPs originates in magnetic structures where Alfvén waves resonate with the loop length on closed magnetic field lines. This concentrates FIP fractionation near the top of the chromosphere. Meanwhile, the source of the SSW may lie near the base of diverging open-field lines surrounding, but outside of, active regions, where such resonance does not exist, allowing fractionation throughout the chromosphere. We also find that energetic particles accelerated from the solar wind itself by shock waves at corotating interaction regions, generally beyond 1 AU, confirm the FIP pattern of the solar wind.

Open Solar Physics Questions - What Can Orbiter Do That Could Not Be Addressed By Existing Missions?

NASA Technical Reports Server (NTRS)

Antiochos, S. K.

2009-01-01

Solar Orbiter represents a revolutionary advance in observing the Sun. Orbiter will have optical and XUV telescopes that will deliver high-resolution images and spectra from vantages points that have never been possible before, dose to the Sun and at high latitudes. At the same time, Orbiter will measure in situ the properties of the solar wind that originate from the observed solar photosphere and corona. In this presentation, Ivvi|/ describe how with its unique vantage points and capabilities, Orbiter will allow us to answer, for the first time, some of the major question in solar physics, such as: Where does the slow wind originate? How do CMEs initiate and evolve? What is the heating mechanism in corona/ loops.

Solar Wind Deflection by Mass Loading in the Martian Magnetosheath Based on MAVEN Observations

NASA Astrophysics Data System (ADS)

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.

Anomalously low C6+/C5+ ratio in solar wind: ACE/SWICS observation

NASA Astrophysics Data System (ADS)

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.

Full-Sun observations for identifying the source of the slow solar wind

PubMed Central

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

The sun and heliosphere at solar maximum

NASA Technical Reports Server (NTRS)

Smith, E. J.; Marsden, R. G.; Balogh, A.; Gloeckler, G.; Geiss, J.; McComas, D. J.; McKibben, R. B.; MacDowall, R. J.; Lanzerotti, L. J.; Krupp, N.;

Bidirectional Energy Cascades and the Origin of Kinetic Alfvenic and Whistler Turbulence in the Solar Wind

NASA Technical Reports Server (NTRS)

Che, H.; Goldstein, M. L.; Vinas, A. F.

2014-01-01

The observed steep kinetic scale turbulence spectrum in the solar wind raises the question of how that turbulence originates. Observations of keV energetic electrons during solar quiet time suggest them as a possible source of free energy to drive kinetic turbulence. Using particle-in-cell simulations, we explore how the free energy released by an electron two-stream instability drives Weibel-like electromagnetic waves that excite wave-wave interactions. Consequently, both kinetic Alfvénic and whistler turbulence are excited that evolve through inverse and forward magnetic energy cascades.

Magnetic Fields and Flows in Open Magnetic Structures

NASA Technical Reports Server (NTRS)

Jones, Harrlson P.

2004-01-01

Open magnetic structures connect the solar surface to the heliosphere and are thus of great interest in solar-terrestrial physics. This talk is primarily an observational review of what is known about magnetic fields and particularly flows in such regions with special focus on coronal holes and origins of the fast solar wind. First evidence of the connection between these two features was seen in correlations of Skylab data with in situ measurements of the solar wind soon after the discovery of coronal holes, which are now known to emanate from unipolar magnetic regions at the photosphere. Subsequently many observations of have been made, ranging from oscillations in the underlying photosphere and chromosphere, to possible beginnings of the solar wind as observed by Doppler shifts in high chromospheric and transition-region lines, to coronagraphic time-lapse studies of outward-moving blobs of material which perhaps trace elements of solar-wind plasma. Some of the many unresolved and controversial issues regarding details of these observations and their association with the solar wind will be discussed.

Formation of Heliospheric Arcs of Slow Solar Wind

NASA Technical Reports Server (NTRS)

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.

Formation of Heliospheric Arcs of Slow Solar Wind

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

The temperature of quiescent streamers during solar cycles 23 and 24

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landi, E.; Testa, P.

2014-05-20

Recent in-situ determinations of the temporal evolution of the charge state distribution in the fast and slow solar wind have shown a general decrease in the degree of ionization of all the elements in the solar wind along solar cycles 23 and 24. Such a decrease has been interpreted as a cooling of the solar corona which occurred during the decline and minimum phase of solar cycle 23 from 2000 to 2010. In the present work, we investigate whether spectroscopic determinations of the temperature of the quiescent streamers show signatures of coronal plasma cooling during cycles 23 and 24. Wemore » measure the coronal electron density and thermal structure at the base of 60 quiescent streamers observed from 1996 to 2013 by SOHO/SUMER and Hinode/EIS and find that both quantities do now show any significant dependence on the solar cycle. We argue that if the slow solar wind is accelerated from the solar photosphere or chromosphere, the measured decrease in the in-situ wind charge state distribution might be due to an increased efficiency in the wind acceleration mechanism at low altitudes. If the slow wind originates from the corona, a combination of density and wind acceleration changes may be responsible for the in-situ results.« less

Discovery of Suprathermal Fe+ in and near Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Christon, S. P.; Hamilton, D. C.; Plane, J. M. C.; Mitchell, D. G.; Grebowsky, J. M.; Spjeldvik, W. N.; Nylund, S. R.

2017-12-01

Suprathermal (87-212 keV/e) singly charged iron, Fe+, has been observed in and near Earth's equatorial magnetosphere using long-term ( 21 years) Geotail/STICS ion composition data. Fe+ is rare compared to dominant suprathermal solar wind and ionospheric origin heavy ions. Earth's suprathermal Fe+ appears to be positively associated with both geomagnetic and solar activity. Three candidate lower-energy sources are examined for relevance: ionospheric outflow of Fe+ escaped from ion layers altitude, charge exchange of nominal solar wind Fe+≥7, and/or solar wind transported inner source pickup Fe+ (likely formed by solar wind Fe+≥7 interaction with near sun interplanetary dust particles, IDPs). Semi-permanent ionospheric Fe+ layers form near 100 km altitude from the tons of IDPs entering Earth's atmosphere daily. Fe+ scattered from these layers is observed up to 1000 km altitude, likely escaping in strong ionospheric outflows. Using 26% of STICS's magnetosphere-dominated data at low-to-moderate geomagnetic activity levels, we demonstrate that solar wind Fe charge exchange secondaries are not an obvious Fe+ source then. Earth flyby and cruise data from Cassini/CHEMS, a nearly identical instrument, show that inner source pickup Fe+ is likely not important at suprathermal energies. Therefore, lacking any other candidate sources, it appears that ionospheric Fe+ constitutes at least an important portion of Earth's suprathermal Fe+, comparable to observations at Saturn where ionospheric origin suprathermal Fe+ has also been observed.

A search for the coronal origins of fast solar wind streams during the whole sun month period

NASA Technical Reports Server (NTRS)

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.;

Magnetic Field Observations near Mercury: Preliminary Results from Mariner 10.

PubMed

Ness, N F; Behannon, K W; Lepping, R P; Whang, Y C; Schatten, K H

1974-07-12

Results are presented from a preliminary analysis of data obtained near Mercury on 29 March 1974 by the NASA-GSFC magnetic field experiment on Mariner 10. Rather unexpectedly, a very well-developed, detached bow shock wave, which develops as the super-Alfvénic solar wind interacts with the planet, has been observed. In addition, a magnetosphere-like region, with maximum field strength of 98 gammas at closest approach (704 kilometers altitude), has been observed, contained within boundaries similar to the terrestrial magnetopause. The obstacle deflecting the solar wind flow is global in size, but the origin of the enhanced magnetic field has not yet been uniquely established. The field may be intrinsic to the planet and distorted by interaction with the solar wind. It may also be associated with a complex induction process whereby the planetary interior-atmosphere-ionosphere interacts with the solar wind flow to generate the observed field by a dynamo action. The complete body of data favors the preliminary conclusion that Mercury has an intrinsic magnetic field. If this is correct, it represents a major scientific discovery in planetary magnetism and will have considerable impact on studies of the origin of the solar system.

Polar rain: Solar coronal electrons in the Earth's magnetosphere

NASA Technical Reports Server (NTRS)

Fairfield, D. H.; Scudder, J. D.

1984-01-01

Low energy electron measurements collected by ISEE 1 reveal the frequent presence of field-aligned fluxes of few hundred eV electrons in he geomagnetic tail lobes. In the northern tail lobe these electrons are most prominent when the interplanetary magnetic field is directed away from the Sun. This characteristic helps identify the electrons as polar rain electrons. By mapping the tail lobe velocity distribution function into the solar wind, previous suggestions that the polar rain is indeed of solar wind origin and is due to the access of electrons to the magnetotail lobe were confirmed. It was demonstrated that the moe energetic component of the polar rain is composed of electrons from the solar wind strahl - a field-aligned component of the solar wind which is difficult to measure but which is thought to be caused by the collisionless transit of hundred eV electrons from the inner solar corona to 1 AU.

Composition of inner-source heavy pickup ions at 1 AU: SOHO/CELIAS/CTOF observations. Implications for the production mechanisms

NASA Astrophysics Data System (ADS)

Taut, A.; Berger, L.; Drews, C.; Wimmer-Schweingruber, R. F.

2015-04-01

Context. Pickup ions in the inner heliosphere mainly originate in two sources, one interstellar and one in the inner solar system. In contrast to the interstellar source that is comparatively well understood, the nature of the inner source has not been clearly identified. Former results obtained with the Solar Wind Ion Composition Spectrometer on-board the Ulysses spacecraft revealed that the composition of inner-source pickup ions is similar, but not equal, to the elemental solar-wind composition. These observations suffered from very low counting statistics of roughly one C+ count per day. Aims: Because the composition of inner-source pickup ions could lead to identifying their origin, we used data from the Charge-Time-Of-Flight sensor on-board the Solar and Heliospheric Observatory. It offers a large geometry factor that results in about 100 C+ counts per day combined with an excellent mass-per-charge resolution. These features enable a precise determination of the inner-source heavy pickup ion composition at 1 AU. To address the production mechanisms of inner-source pickup ions, we set up a toy model based on the production scenario involving the passage of solar-wind ions through thin dust grains to explain the observed deviations of the inner-source PUI and the elemental solar-wind composition. Methods: An in-flight calibration of the sensor allows identification of heavy pickup ions from pulse height analysis data by their mass-per-charge. A statistical analysis was performed to derive the inner-source heavy pickup ion relative abundances of N+, O+, Ne+, Mg+, Mg2+, and Si+ compared to C+. Results: Our results for the inner-source pickup ion composition are in good agreement with previous studies and confirm the deviations from the solar-wind composition. The large geometry factor of the Charge-Time-of-Flight sensor even allowed the abundance ratios of the two most prominent pickup ions, C+ and O+, to be investigated at varying solar-wind speeds. We found that the O+/C+ ratio increases systematically with higher solar-wind speeds. This observation is an unprecedented feature characterising the production of inner-source pickup ions. Comparing our observations to the toy model results, we find that both the deviation from the solar-wind composition and the solar-wind-speed dependent O+/C+ ratio can be explained.

Elemental composition of solar energetic particles. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Cook, W. R., III

1981-01-01

The Low Energy Telescopes on the Voyager spacecraft are used to measure the elemental composition (2 or = Z or = 28) and energy spectra (5 to 15 MeV/nucleon) of solar energetic particles (SEPs) in seven large flare events. Four flare events are selected which have SEP abundance ratios approximately independent of energy/nucleon. The abundances for these events are compared from flare to flare and are compared to solar abundances from other sources: spectroscopy of the photosphere and corona, and solar wind measurements. The four flare average SEP composition is significantly different from the solar composition determined by photospheric spectroscopy. The average SEP composition is in agreement with solar wind abundance results and with a number of recent coronal abundance measurements. The evidence for a common depletion of oxygen in SEPs, the corona and the solar wind relative to the photosphere suggest that the SEPs originate in the corona and that both the SEPs and solar wind sample a coronal composition which is significantly and persistently different from that of the photosphere.

Origin and Ion Charge State Evolution of Solar Wind Transients 4 - 7 August 2011

NASA Astrophysics Data System (ADS)

Rodkin, Denis; Goryaev, Farid; Pagano, Paolo; Gibb, Gordon; Slemzin, Vladimir; Shugay, Yulia; Veselovsky, Igor; Mackay, Duncan

2017-04-01

Identification of transients and their origins on the Sun is one of the most important problems of the space weather forecasting. In our work, we present a case study of the complex event consisting of several solar wind transients detected by ACE on 4 - 7 August 2011, that caused a geomagnetic storm with Dst= - 110 nT. The supposed coronal sources - three flares and coronal mass ejections (CMEs) occurred on 2 - 4 August 2011 in the active region AR 11261. To investigate the solar origins and formation of these transients, we studied kinematic and thermodynamic properties of expanding coronal structures using the SDO/AIA EUV images and the differential emission measure (DEM) diagnostics. The Helioseismic and Magnetic Imager (HMI) magnetic field maps were used as the input data for the 3D numerical model to describe the flux rope ejection. We characterize the early phase of the flux rope ejection in the corona, where the usual three-component CME structure formed. The flux rope ejected with the speed about 200 km/s to the height of 0.25 Rsun. The kinematics of the modeled CME front well agrees with the STEREO EUV measurements. Using the results of the plasma diagnostics and MHD modeling, we calculated the ion charge ratios of carbon and oxygen as well as the mean charge state of iron ions of the 2 August 2011 CME taking into account the processes of heating, cooling, expansion, ionization and recombination of the moving plasma in the corona up to the freeze-in region. We estimated a probable heating rate of the CME plasma in the low corona by matching the calculated ion composition parameters of the CME with that measured in-situ parameters of the solar wind transients. We also consider the similarities and discrepancies between the results of the MHD simulation and the observation of the event. Our results show that analysis of the ion composition of CMEs enables to disclose a relationship between parameters of the solar wind transients and properties of their solar origins, which opens new possibilities to validate and improve the solar wind forecasting models.

Coronal Magnetic Field Topology and Source of Fast Solar Wind

NASA Technical Reports Server (NTRS)

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.

Heliophysics 2009 Roadmap and Global Change: Possibilities for Improved Understanding of the Connection

NASA Technical Reports Server (NTRS)

Spann, Jim

2010-01-01

Heliophysics is the science that includes all aspects of the research needed to understand the Sun and its effects on the Earth and the solar system. Six science targets: 1. Origins of Near-Earth Plasma - to understand the origin and transport of terrestrial plasma from its source to the magnetosphere and solar wind. 2. Solar Energetic Particle Acceleration and Transport - to understand how and where solar eruptions accelerate energetic particles that reach Earth. 3. Ion-Neutral Coupling in the Atmosphere - to understand how neutral winds control ionospheric variability. 4. Climate Impacts of Space Radiation - to understand our atmosphere s response to auroral, radiation belt, and solar energetic particles, and the associated effects on nitric oxide (NO) and ozone. 5. Dynamic Geospace Coupling - to understand how magnetospheric dynamics provides energy into the coupled ionosphere-magnetosphere system. 6. Heliospheric Magnetics - to understand the flow and dynamics of transient magnetic structures form the solar interior to Earth.

Anomalously low C{sup 6+}/C{sup 5+} ratio in solar wind: ACE/SWICS observation

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

A Model fot the Sources of the Slow Solar Wind

NASA Technical Reports Server (NTRS)

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

2011-01-01

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

Solar wind physics

NASA Technical Reports Server (NTRS)

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.

The Effects of Differential Rotation on the Magnetic Structure of the Solar Corona: MHD Simulations

NASA Technical Reports Server (NTRS)

Lionello, Roberto; Riley, Pete; Linker, Jon A.; Mikic, Zoran

2004-01-01

Coronal holes are magnetically open regions from which the solar wind streams. Magnetic reconnection has been invoked to reconcile the apparently rigid rotation of coronal holes with the differential rotation of magnetic flux in the photosphere. This mechanism might also be relevant to the formation of the slow solar wind, the properties of which seem to indicate an origin from the opening of closed magnetic field lines. We have developed a global MHD model to study the effect of differential rotation on the coronal magnetic field. Starting from a magnetic flux distribution similar to that of Wang et al., which consists of a bipolar magnetic region added to a background dipole field, we applied differential rotation over a period of 5 solar rotations. The evolution of the magnetic field and of the boundaries of coronal holes are in substantial agreement with the findings of Wang et al.. We identified examples of interchange reconnection and other changes of topology of the magnetic field. Possible consequences for the origin of the slow solar wind are also discussed.

Effect on the Lunar Exosphere of a CME Passage

NASA Technical Reports Server (NTRS)

Killen, Rosemary M.; Hurley, Dana M.; Farrell, William M.; Sarantos, Menelaos

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 the sputter yield can be noticeably increased in the case of a good insulating surface. 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. The heavy ion component, especially the He++ component, greatly enhances the total sputter yield during times when the heavy ion population is enhanced, most notably during a coronal mass ejection. To simulate the effect on the lunar exosphere of a CME passage past the Moon, we ran a Monte Carlo code for the species Na, K, Mg and Ca.

Ionosphere of venus: first observations of the effects of dynamics on the dayside ion composition.

PubMed

Taylor, H A; Brinton, H C; Bauer, S J; Hartle, R E; Cloutier, P A; Michel, F C; Daniell, R E; Donahue, T M; Maehl, R C

1979-02-23

Bennett radio-frequency ion mass spectrometers have returned the first in situ measurements of the Venus dayside ion composition, including evidence of pronounced structural variability resulting from a dynamic interaction with the solar wind. The ionospheric envelope, dominated above 200 kilometers by O(+), responds dramatically to variations in the solar wind pressure, Which is observed to compress the thermal ion distributions from heights as great as 1800 kilometers inward to 280 kilometers. At the thermal ion boundary, or ionopause, the ambient ions are swept away by the solar wind, such that a zone of accelerated suprathermnal plasma is encountered. At higher altitudes, extending outward on some orbits for thousands of kilometers to the bows shock, energetic ion currents are detected, apparently originating from the shocked solar wind plasma. Within the ionosphere, observations of pass-to-pass differences in the ion scale heights are indicative of the effects of ion convection stimlulated by the solar wind interaction.

Short, large amplitude speed enhancements in the near-Sun fast solar wind

NASA Astrophysics Data System (ADS)

Horbury, T. S.; Matteini, L.; Stansby, D.

2018-04-01

We report the presence of intermittent, short discrete enhancements in plasma speed in the near-Sun high speed solar wind. Lasting tens of seconds to minutes in spacecraft measurements at 0.3 AU, speeds inside these enhancements can reach 1000 km/s, corresponding to a kinetic energy up to twice that of the bulk high speed solar wind. These events, which occur around 5% of the time, are Alfvénic in nature with large magnetic field deflections and are the same temperature as the surrounding plasma, in contrast to the bulk fast wind which has a well-established positive speed-temperature correlation. The origin of these speed enhancements is unclear but they may be signatures of discrete jets associated with transient events in the chromosphere or corona. Such large short velocity changes represent a measurement and analysis challenge for the upcoming Parker Solar Probe and Solar Orbiter missions.

Periodic Density Structures and the Origin of the Slow Solar Wind

NASA Technical Reports Server (NTRS)

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.

Self-Consistent and Time-Dependent Solar Wind Models

NASA Technical Reports Server (NTRS)

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.

Nucleosynthesis of Mo and Ru isotopes in neutrino-driven winds

NASA Astrophysics Data System (ADS)

Bliss, Julia; Arcones, Almudena

2018-01-01

The solar system origin of the p-isotopes 92,94Mo and 96,98Ru is a long-lasting mystery. Several astrophysical scenarios failed to explain their formation. Moreover, SiC X grains show a different abundance ratio of 95,97Mo than in the solar system. We have investigated if neutrino-driven winds can offer a solution to those problems.

An Anomalous Composition in Slow Solar Wind as a Signature of Magnetic Reconnection in its Source Region

NASA Astrophysics Data System (ADS)

Zhao, L.; Landi, E.; Lepri, S. T.; Kocher, M.; Zurbuchen, T. H.; Fisk, L. A.; Raines, J. M.

2017-01-01

In this paper, we study a subset of slow solar winds characterized by an anomalous charge state composition and ion temperatures compared to average solar wind distributions, and thus referred to as an “Outlier” wind. We find that although this wind is slower and denser than normal slow wind, it is accelerated from the same source regions (active regions and quiet-Sun regions) as the latter and its occurrence rate depends on the solar cycle. The defining property of the Outlier wind is that its charge state composition is the same as that of normal slow wind, with the only exception being a very large decrease in the abundance of fully charged species (He2+, C6+, N7+, O8+, Mg12+), resulting in a significant depletion of the He and C element abundances. Based on these observations, we suggest three possible scenarios for the origin of this wind: (1) local magnetic waves preferentially accelerating non-fully stripped ions over fully stripped ions from a loop opened by reconnection; (2) depleted fully stripped ions already contained in the corona magnetic loops before they are opened up by reconnection; or (3) fully stripped ions depleted by Coulomb collision after magnetic reconnection in the solar corona. If any one of these three scenarios is confirmed, the Outlier wind represents a direct signature of slow wind release through magnetic reconnection.

Long-period variations of wind parameters in the mesopause region and the solar cycle dependence

NASA Technical Reports Server (NTRS)

Greisiger, K. M.; Schminder, R.; Kuerschner, D.

1987-01-01

The solar cycle dependence of wind parameters below 100 km on the basis of long term continuous ionospheric drift measurements in the low frequency range is discussed. For the meridional prevailing wind no significant variation was found. The same comparison as for winter was done for summer where the previous investigations gave no correlation. Now the radar meteor wind measurement values, too, showed a significant negative correlation of the zonal prevailing wind with solar activity for the years 1976 to 1983. The ionospheric drift measurement results of Collm have the same tendency but a larger dispersion due to the lower accuracy of the harmonic analysis because of the shorter daily measuring interval in summer. Continuous wind observations in the upper mesopause region over more than 20 years revealed distinct long term variations, the origin of which cannot be explained with the present knowledge.

The low-frequency continuum as observed in the solar wind from ISEE 3 - Thermal electrostatic noise

NASA Technical Reports Server (NTRS)

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.

How Well Does the S-Web Theory Predict In-Situ Observations of the Slow Solar Wind?

NASA Astrophysics Data System (ADS)

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.

Recent Progress in Understanding the Origin and Acceleration of Suprathermal Ions and Electrons

NASA Astrophysics Data System (ADS)

Desai, Mihir; Dayeh, Maher

2017-04-01

Ions and electrons with energies that lie above (i.e., ˜2 keV) that of the core or bulk solar wind protons and electrons are known as suprathermal particles. Observations over the last decade have shown that such suprathermal particles are an important constituent of the overall seed population that is accelerated in solar and interplanetary events. Despite their increased level of importance, where these populations originate from and how they are accelerated remains highly controversial. This is partly due to the fact that these particles exist in the so-called tail regions of the corresponding solar wind distributions where high temporal and sensitivity measurements are sparse. Moreover, observations comprising long-term averages (between ˜hours to more than a day) have shown conflicting results. For instance, below ˜40 keV/nucleon the ion differential intensities in the solar wind frame appear to exhibit a near-constant power-law spectral slope of ˜1.5, perhaps indicating a universal acceleration mechanism. In contrast, at energies greater than ˜40 keV/nucleon, the ion composition changes with solar activity and the energy spectra are significantly steeper, perhaps indicating that the suprathermal pool of material also comprises lower-energy particle populations accelerated in corotating interaction regions, interplanetary shocks, and solar energetic particle events. This talk discusses recent observations of suprathermal ions and electrons in terms of state-of-the-art theories and models that have been put forward to account for their origins and acceleration.

Modelling Solar Energetic Particle Propagation in Realistic Heliospheric Solar Wind Conditions Using a Combined MHD and Stochastic Differential Equation Approach

NASA Astrophysics Data System (ADS)

Wijsen, N.; Poedts, S.; Pomoell, J.

2017-12-01

Solar energetic particles (SEPs) are high energy particles originating from solar eruptive events. These particles can be energised at solar flare sites during magnetic reconnection events, or in shock waves propagating in front of coronal mass ejections (CMEs). These CME-driven shocks are in particular believed to act as powerful accelerators of charged particles throughout their propagation in the solar corona. After escaping from their acceleration site, SEPs propagate through the heliosphere and may eventually reach our planet where they can disrupt the microelectronics on satellites in orbit and endanger astronauts among other effects. Therefore it is of vital importance to understand and thereby build models capable of predicting the characteristics of SEP events. The propagation of SEPs in the heliosphere can be described by the time-dependent focused transport equation. This five-dimensional parabolic partial differential equation can be solved using e.g., a finite difference method or by integrating a set of corresponding first order stochastic differential equations. In this work we take the latter approach to model SEP events under different solar wind and scattering conditions. The background solar wind in which the energetic particles propagate is computed using a magnetohydrodynamic model. This allows us to study the influence of different realistic heliospheric configurations on SEP transport. In particular, in this study we focus on exploring the influence of high speed solar wind streams originating from coronal holes that are located close to the eruption source region on the resulting particle characteristics at Earth. Finally, we discuss our upcoming efforts towards integrating our particle propagation model with time-dependent heliospheric MHD space weather modelling.

A Model for the Sources of the Slow Solar Wind

NASA Technical Reports Server (NTRS)

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.

A Model for the Sources of the Slow Solar Wind

NASA Astrophysics Data System (ADS)

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.

Green spherules from Apollo 15 - Inferences about their origin from inert gas measurements.

NASA Technical Reports Server (NTRS)

Lakatos, S.; Yaniv, A.; Heymann, D.

1973-01-01

Green spherules from the 'clod' 15426 and from fines 15421 contain about 100 times less trapped inert gases than normal bulk fines from Apollo 15. These spherules have apparently never been directly exposed to the solar wind. Spherules from other fines contain about 10 times more trapped gas than those from the 'clod.' The gas in the former is surface correlated. However, spherules from fines 15401 are exceptionally gas-poor. The trapped gases can be of solar-wind origin, but this origin requires a two-stage model for the spherules from the clods. Another possibility is that the gases were absorbed from an ambient gas phase. The trapped gases may also be assumed to represent primordial lunar gas. The composition of this gas is then similar to the 'solar' or 'unfractionated' component of gas-rich meteorites, but unlike that in most of the carbonaceous chondrites.

Lessons Learned from 10 Years of STEREO Solar Wind Observations

NASA Astrophysics Data System (ADS)

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.

The MAVEN Solar Wind Electron Analyzer

NASA Astrophysics Data System (ADS)

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.

Origin of the Wang-Sheeley-Arge solar wind model

NASA Astrophysics Data System (ADS)

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.

Solar Polar ORbit Telescope (SPORT): A Potential Space Weather Mission of China

NASA Astrophysics Data System (ADS)

Liu, Y. D.; Xiong, M.; Wu, J.; Liu, H.; Zheng, J.; Li, B.; Zhang, C.; Sun, W.

2013-12-01

We describe a spacecraft mission, named Solar Polar ORbit Telescope (SPORT), which is currently under a scientific and engineering background study in China. SPORT was originally proposed in 2004 by the National Space Science Center, Chinese Academy of Sciences. It will carry a suite of remote-sensing and in-situ instruments to observe coronal mass ejections (CMEs), solar high-latitude magnetism, and the fast solar wind from a polar orbit around the Sun. It is intended to be the first mission that carries remote-sensing instruments from a high-latitude orbit around the Sun, the first mission that could image interplanetary CMEs at radio wavelengths from space, and the first mission that could measure solar high-latitude magnetism leading to eruptions and the fast solar wind. The first extended view of the polar region of the Sun and the ecliptic plane enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere and solar high-latitude magnetism giving rise to eruptions and the fast solar wind.

Voyager Approaches Final Frontier Artist Concept

NASA Image and Video Library

2003-12-12

An artist's concept illustrates the positions of the Voyager spacecraft in relation to structures formed around our Sun by the solar wind. Also illustrated is the termination shock, a violent region the spacecraft must pass through before reaching the outer limits of the solar system. At the termination shock, the supersonic solar wind abruptly slows from an average speed of 400 kilometers per second to less than 100 kilometer per second (900,000 to less than 225,000 miles per hour). Beyond the termination shock is the solar system's final frontier, the heliosheath, a vast region where the turbulent and hot solar wind is compressed as it presses outward against the interstellar wind that is beyond the heliopause. A bow shock likely forms as the interstellar wind approaches and is deflected around the heliosphere, forcing it into a teardrop-shaped structure with a long, comet-like tail. The exact location of the termination shock is unknown, and it originally was thought to be closer to the Sun than Voyager 1 currently is. As Voyager 1 cruised ever farther from the Sun, it confirmed that all the planets are inside an immense bubble blown by the solar wind and the termination shock was much more distant. http://photojournal.jpl.nasa.gov/catalog/PIA04927

Number density structures in the inner heliosphere

NASA Astrophysics Data System (ADS)

Stansby, D.; Horbury, T. S.

2018-06-01

Aims: The origins and generation mechanisms of the slow solar wind are still unclear. Part of the slow solar wind is populated by number density structures, discrete patches of increased number density that are frozen in to and move with the bulk solar wind. In this paper we aimed to provide the first in-situ statistical study of number density structures in the inner heliosphere. Methods: We reprocessed in-situ ion distribution functions measured by Helios in the inner heliosphere to provide a new reliable set of proton plasma moments for the entire mission. From this new data set we looked for number density structures measured within 0.5 AU of the Sun and studied their properties. Results: We identified 140 discrete areas of enhanced number density. The structures occurred exclusively in the slow solar wind and spanned a wide range of length scales from 50 Mm to 2000 Mm, which includes smaller scales than have been previously observed. They were also consistently denser and hotter that the surrounding plasma, but had lower magnetic field strengths, and therefore remained in pressure balance. Conclusions: Our observations show that these structures are present in the slow solar wind at a wide range of scales, some of which are too small to be detected by remote sensing instruments. These structures are rare, accounting for only 1% of the slow solar wind measured by Helios, and are not a significant contribution to the mass flux of the solar wind.

The solar probe and coronal dynamics

NASA Technical Reports Server (NTRS)

Belcher, J.; Heinemann, M.; Goodrich, C.

1978-01-01

The discovery of coronal holes led to basic changes in ideas about the structure of the low corona and its expansion into the solar wind. The nature of the energy flux is not understood. Current ideas include enhanced thermal conductivities, extended MHD wave heating, and wave momentum transfer, all in rapidly diverging geometries. There is little feel for the relative importance of these processes. The Solar Probe, with its penetration deep into the solar corona, could lead to observational constraints on their relative importance, and thus to an understanding of the origin of the solar wind. Observations from the Solar Probe will also bear on such questions as to whether small scale "intrastream" structure is common close to the Sun in open field-line regions, whether the properties of the wind are pronouncedly different over closed and open field-line regions at five solar radii, and many others. The resolution of these questions requires measurements of the magnetic field and of the proton and electron distribution functions.

EVIDENCE FOR POLAR X-RAY JETS AS SOURCES OF MICROSTREAM PEAKS IN THE SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

A theory of local and global processes which affect solar wind electrons. I - The origin of typical 1 AU velocity distribution functions - Steady state theory

NASA Technical Reports Server (NTRS)

Scudder, J. D.; Olbert, S.

1979-01-01

A kinetic theory for the velocity distribution of solar wind electrons which illustrates the global and local properties of the solar wind expansion is proposed. By means of the Boltzmann equation with the Krook collision operator accounting for Coulomb collisions, it is found that Coulomb collisions determine the population and shape of the electron distribution function in both the thermal and suprathermal energy regimes. For suprathermal electrons, the cumulative effects of Coulomb interactions are shown to take place on the scale of the heliosphere itself, whereas the Coulomb interactions of thermal electrons occur on a local scale near the point of observation (1 AU). The bifurcation of the electron distribution between thermal and suprathermal electrons is localized to the deep solar corona (1 to 10 solar radii).

Lunar Solar Origins Exploration (LunaSOX)

NASA Technical Reports Server (NTRS)

Cooper, John F.; King, Joseph H.; Papitashvili, Natasha; Lipatov, Alexander S.; Sittler, Edward C.; Hartle, Richard E.

2011-01-01

The Moon offers a unique vantage point from which to investigate the Sun and its interaction via the solar wind magnetic fields, plasma, and energetic particles with the geospace system including the Moon itself. The lunar surface and exosphere provide in part a record of solar coronal plasma material input and resultant space weathering over billions of years. The structure and dynamics of solar wind interactions with the Moon provide an accessible near-Earth laboratory environment for study of general solar wind interactions with the vast multitude of airless asteroidal bodies of the inner solar system. Spacecraft in lunar orbit have the often simultaneous opportunity, except when in the Earth's magnetosphere, to make in-situ compositional measurements of the solar wind plasma and to carry out remote observations from the Moon of the solar corona, potentially enabled by lunar limb occultation of the solar disk. The LunaSOX project at NASA Goddard Space Flight Center is addressing these heliophysical science objectives from and of the Moon with support from NASA's Lunar Advanced Science and Exploration Research (LASER) program: (1) specify history of solar wind parameters at and sunward of the Moon through enhanced access (http://lunasox.gsfc.nasa.gov/) to legacy and operational mission data products from the Apollo era to the present, (2) model field and plasma interactions with the lunar surface, exosphere, and wake, as constrained by the available data, through hybrid kinetic code simulations, and (3) advance mission concepts for heliophysics from and of the Moon.

EVOLUTION OF INTERMITTENCY IN THE SLOW AND FAST SOLAR WIND BEYOND THE ECLIPTIC PLANE

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Sources of the solar wind - the heliospheric point of view

NASA Astrophysics Data System (ADS)

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.

Telescoping in on the Microscopic Origins of the Fast Solar Wind

NASA Astrophysics Data System (ADS)

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 coronal heating and solar wind acceleration.

Genesis Solar Wind Array Collector Fragments Post-Recovery Status

NASA Astrophysics Data System (ADS)

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, L.; Landi, E.; Lepri, S. T.

In this paper, we study a subset of slow solar winds characterized by an anomalous charge state composition and ion temperatures compared to average solar wind distributions, and thus referred to as an “Outlier” wind. We find that although this wind is slower and denser than normal slow wind, it is accelerated from the same source regions (active regions and quiet-Sun regions) as the latter and its occurrence rate depends on the solar cycle. The defining property of the Outlier wind is that its charge state composition is the same as that of normal slow wind, with the only exceptionmore » being a very large decrease in the abundance of fully charged species (He{sup 2+}, C{sup 6+}, N{sup 7+}, O{sup 8+}, Mg{sup 12+}), resulting in a significant depletion of the He and C element abundances. Based on these observations, we suggest three possible scenarios for the origin of this wind: (1) local magnetic waves preferentially accelerating non-fully stripped ions over fully stripped ions from a loop opened by reconnection; (2) depleted fully stripped ions already contained in the corona magnetic loops before they are opened up by reconnection; or (3) fully stripped ions depleted by Coulomb collision after magnetic reconnection in the solar corona. If any one of these three scenarios is confirmed, the Outlier wind represents a direct signature of slow wind release through magnetic reconnection.« less

Observations of solar wind ion charge exchange in the comet Halley coma

NASA Technical Reports Server (NTRS)

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.

Solar Wind 0.1-1 keV Electrons in the Corotating Interaction Regions

NASA Astrophysics Data System (ADS)

Wang, L.; Tao, J.; Li, G.; Wimmer-Schweingruber, R. F.; Jian, L. K.; He, J.; Tu, C.; Tian, H.; Bale, S. D.

2017-12-01

Here we present a statistical study of the 0.1-1 keV suprathermal electrons in the undisturbed and compressed slow/fast solar wind, for the 71 corotating interaction regions (CIRs) with good measurements from the WIND 3DP and MFI instruments from 1995 to 1997. For each of these CIRs, we separate the strahl and halo electrons based on their different behaviors in pitch angle distributions in the undisturbed and compressed solar wind. We fit both the strahl and halo energy spectra to a kappa function with an index κ index and effective temperature Teff, and calculate the pitch-angle width at half-maximum (PAHM) of the strahl population. We also integrate the electron measurements between 0.1 and 1.0 keV to obtain the number density n and average energy Eavg for the strahl and halo populations. We find that for both the strahl and halo populations within and around these CIRs, the fitted κ index strongly correlates with Teff, similar to the quiet-time solar wind (Tao et al., ApJ, 2016). The number density of both the strahl and halo shows a strong positive correlation with the electron core temperature. The strahl number density ns is correlated with the magnitude of interplanetary magnetic field, and the strahl PAHM width is anti-correlated with the solar wind speed. These results suggest that the origin of strahl electrons from the solar corona is likely related to the electron core temperature and magnetic field strength, while the production of halo electrons in the interplanetary medium could depend on the solar wind velocity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desai, Mihir I., E-mail: mdesai@swri.edu; Department of Physics & Astronomy, University of Texas at San Antonio, TX 782, USA.; Dayeh, Maher A.

Observations over the last decade have shown that suprathermal ions with energies above that of the core or bulk solar wind protons (i.e., ~1-2 keV/nucleon) are an important constituent of the overall seed population that is accelerated in solar and interplanetary events. Despite the recent recognition of their importance, the origin of these populations and the method of their acceleration remains poorly understood. This is partly due to the fact that these particles exist in the so-called tail regions of the corresponding solar wind distributions where high temporal and sensitivity measurements are sparse. Moreover, observations comprising long-term averages (between hoursmore » to more than a day) show conflicting results. For instance, below ~40 keV/nucleon the ion differential intensities in the solar wind frame appear to exhibit a near-constant power-law spectral slope of ~1.5, perhaps indicating a universal acceleration mechanism. In contrast, at energies greater than ~40 keV/nucleon, the ion composition changes with solar activity, and the energy spectra are significantly steeper, perhaps indicating that the suprathermal pool of material also comprises lower-energy particle populations accelerated in corotating interaction regions, interplanetary shocks, and solar energetic particle events. This paper discusses key observations of suprathermal ions and electrons in terms of state-of-the-art theories and models that have been put forward to account for their origin and acceleration.« less

Status of Reconstruction of Fragmented Diamond-on-Silicon Collector From Genesis Spacecraft Solar Wind Concentrator

NASA Technical Reports Server (NTRS)

Rodriquez, Melissa C.; Calaway, M. C.; McNamara, K. M.; Hittle, J. D.

2009-01-01

In addition to passive solar wind collector surfaces, the Genesis Discovery Mission science canister had on board an electrostatic concave mirror for concentrating the solar wind ions, known as the concentrator . The 30-mm-radius collector focal point (the target) was comprised of 4 quadrants: two of single crystal SiC, one of polycrystalline 13C diamond and one of diamond-like-carbon (DLC) on a silicon substrate. [DLC-on-silicon is also sometimes referenced as Diamond-on-silicon, DOS.] Three of target quadrants survived the hard landing intact, but the DLC-on-silicon quadrant fractured into numerous pieces (Fig. 1). This abstract reports the status of identifying the DLC target fragments and reconstructing their original orientation.

Low-energy ion outflow modulated by the solar wind energy input

NASA Astrophysics Data System (ADS)

Li, Kun; Wei, Yong; Andre, Mats; Eriksson, Anders; Haaland, Stein; Kronberg, Elena; Nilsson, Hans; Maes, Lukas

2017-04-01

Due to the spacecraft charging issue, it has been difficult to measure low-energy ions of ionospheric origin in the magnetosphere. A recent study taking advantage of the spacecraft electric potential has found that the previously 'hidden' low-energy ions is dominant in the magnetosphere. This comprehensive dataset of low-energy ions allows us to study the relationship between the ionospheric outflow and energy input from the solar wind (ɛ). In this study, we discuss the ratios of the solar wind energy input to the energy of the ionospheric outflow. We show that the ɛ controls the ionospheric outflow when the ɛ is high, while the ionospheric outflow does not systematically change with the ɛ when the ɛ is low.

IMF orientation, solar wind velocity, and Pc 3-4 signals - A joint distribution

NASA Technical Reports Server (NTRS)

Greenstadt, E. W.; Singer, H. J.; Russell, C. T.; Olson, J. V.

1979-01-01

Separate studies using the same micropulsation data base in the period range 10-150 s have shown earlier that signal levels recorded during September, October, and November 1969 at Calgary correlated positively with both solar-wind alignment of the IMF and solar-wind speed, but each correlation contained enough scatter to allow for the influence of the other factor. In this report, joint correlations of velocity and field direction with parameters representing hourly distributions rather than minima of IMF orientation angle display the relative effect of the two agents on magnetic pulsation signal levels. The joint correlations reduce the overall scatter and show that solar-wind speeds above 200-300 km/s and angles between the IMF and the sun-earth line of less than 50-60 deg are associated with enlarged magnetic pulsation amplitudes. These threshold effects tend to support both the bow-shock origin and the Kelvin-Helmholtz amplification of daytime signal transients in the Pc 3, 4 period ranges.

3D Anisotropy of Solar Wind Turbulence, Tubes, or Ribbons?

NASA Astrophysics Data System (ADS)

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.

Spectroscopic Measurements of the Ion Velocity Distribution at the Base of the Fast Solar Wind

NASA Astrophysics Data System (ADS)

Jeffrey, Natasha L. S.; Hahn, Michael; Savin, Daniel W.; Fletcher, Lyndsay

2018-03-01

In situ measurements of the fast solar wind reveal non-thermal distributions of electrons, protons, and minor ions extending from 0.3 au to the heliopause. The physical mechanisms responsible for these non-thermal properties and the location where these properties originate remain open questions. Here, we present spectroscopic evidence, from extreme ultraviolet spectroscopy, that the velocity distribution functions (VDFs) of minor ions are already non-Gaussian at the base of the fast solar wind in a coronal hole, at altitudes of <1.1 R ⊙. Analysis of Fe, Si, and Mg spectral lines reveals a peaked line-shape core and broad wings that can be characterized by a kappa VDF. A kappa distribution fit gives very small kappa indices off-limb of κ ≈ 1.9–2.5, indicating either (a) ion populations far from thermal equilibrium, (b) fluid motions such as non-Gaussian turbulent fluctuations or non-uniform wave motions, or (c) some combination of both. These observations provide important empirical constraints for the source region of the fast solar wind and for the theoretical models of the different acceleration, heating, and energy deposition processes therein. To the best of our knowledge, this is the first time that the ion VDF in the fast solar wind has been probed so close to its source region. The findings are also a timely precursor to the upcoming 2018 launch of the Parker Solar Probe, which will provide the closest in situ measurements of the solar wind at approximately 0.04 au (8.5 solar radii).

Neutral escape at Mars induced by the precipitation of high-energy protons and hydrogen atoms of the solar wind origin

NASA Astrophysics Data System (ADS)

Shematovich, Valery I.

2017-04-01

One of the first surprises of the NASA MAVEN mission was the observation by the SWIA instrument of a tenuous population of protons with solar wind energies travelling anti-sunward near periapsis, at altitudes of 150-250 km (Halekas et al., 2015). While the penetration of solar wind protons to low altitude is not completely unexpected given previous Mars Express results, this population maintains exactly the same velocity as the solar wind observed. From previous studies it was known that some fraction of the solar wind can interact with the extended corona of Mars. By charge exchange with the neutral particles in this corona, some fraction of the incoming solar wind protons can gain an electron and become an energetic neutral hydrogen atom. Once neutral, these particles penetrate through the Martian induced magnetosphere with ease, with free access to the collisional atmosphere/ionosphere. The origin, kinetics and transport of the suprathermal O atoms in the transition region (from thermosphere to exosphere) of the Martian upper atmosphere due to the precipitation of the high-energy protons and hydrogen atoms are discussed. Kinetic energy distribution functions of suprathermal and superthermal (ENA) oxygen atoms formed in the Martian upper atmosphere were calculated using the kinetic Monte Carlo model (Shematovich et al., 2011, Shematovich, 2013) of the high-energy proton and hydrogen atom precipitation into the atmosphere. These functions allowed us: (a) to estimate the non-thermal escape rates of neutral oxygen from the Martian upper atmosphere, and (b) to compare with available MAVEN measurements of oxygen corona. Induced by precipitation the escape of hot oxygen atoms may become dominant under conditions of extreme solar events - solar flares and coronal mass ejections, - as it was shown by recent observations of the NASA MAVEN spacecraft (Jakosky et al., 2015). This work is supported by the RFBR project and by the Basic Research Program of the Praesidium of the Russian Academy of Sciences (Program 1.7). References Shematovich, Solar System Res., 2013, v.47, 437. Shematovich et al., J. Geophys. Res., 2011, v.116, A11320. Halekas et al., Geophys. Res. Lett., 2015, v. 42. doi:10.1002/2015GL064781. Jakosky et al., Science, 2015, v. 350, Issue 6261, aad0210:1-7.

Lunar surface magnetometer experiment

NASA Technical Reports Server (NTRS)

Dyal, P.; Parkin, C. W.; Sonett, C. P.

1972-01-01

The Apollo 15 lunar-surface magnetometer (LSM) is one of a network of magnetometers that have been deployed on the moon to study intrinsic remanent magnetic fields and global magnetic response of the moon to large-scale solar and terrestrial magnetic fields. From these field measurements, properties of the lunar interior such as magnetic permeability, electrical conductivity, and temperature can be calculated. In addition, correlation with solar-wind-spectrometer data allows study of the the solar-wind plasma interaction with the moon and, in turn, investigation of the resulting absorption of gases and accretion of an ionosphere. These physical parameters and processes determined from magnetometer measurements must be accounted for by comprehensive theories of origin and evolution of the moon and solar system.

"Driverless" Shocks in the Interplanetary Medium

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Kaiser, M. L.; Lara, A.

1999-01-01

Many interplanetary shocks have been detected without an obvious driver behind them. These shocks have been thought to be either blast waves from solar flares or shocks due to sudden increase in solar wind speed caused by interactions between large scale open and closed field lines of the Sun. We investigated this problem using a set of interplanetary shock detected {\\it in situ} by the Wind space craft and tracing their solar origins using low frequency radio data obtained by the Wind/WAVES experiment. For each of these "driverless shocks" we could find a unique coronal mass ejections (CME) event observed by the SOHO (Solar and Heliospheric Observatory) coronagraphs. We also found that these CMEs were ejected at large angles from the Sun-Earth line. It appears that the "driverless shocks" are actually driver shocks, but the drivers were not intercepted by the spacecraft. We conclude that the interplanetary shocks are much more extended than the driving CMEs.

Hydrodynamic Models of Line-Driven Accretion Disk Winds III: Local Ionization Equilibrium

NASA Technical Reports Server (NTRS)

Pereyra, Nicolas Antonio; Kallman, Timothy R.; White, Nicholas E. (Technical Monitor)

2002-01-01

We present time-dependent numerical hydrodynamic models of line-driven accretion disk winds in cataclysmic variable systems and calculate wind mass-loss rates and terminal velocities. The models are 2.5-dimensional, include an energy balance condition with radiative heating and cooling processes, and includes local ionization equilibrium introducing time dependence and spatial dependence on the line radiation force parameters. The radiation field is assumed to originate in an optically thick accretion disk. Wind ion populations are calculated under the assumption that local ionization equilibrium is determined by photoionization and radiative recombination, similar to a photoionized nebula. We find a steady wind flowing from the accretion disk. Radiative heating tends to maintain the temperature in the higher density wind regions near the disk surface, rather than cooling adiabatically. For a disk luminosity L (sub disk) = solar luminosity, white dwarf mass M(sub wd) = 0.6 solar mass, and white dwarf radii R(sub wd) = 0.01 solar radius, we obtain a wind mass-loss rate of M(sub wind) = 4 x 10(exp -12) solar mass yr(exp -1) and a terminal velocity of approximately 3000 km per second. These results confirm the general velocity and density structures found in our earlier constant ionization equilibrium adiabatic CV wind models. Further we establish here 2.5D numerical models that can be extended to QSO/AGN winds where the local ionization equilibrium will play a crucial role in the overall dynamics.

On improvement to the Shock Propagation Model (SPM) applied to interplanetary shock transit time forecasting

NASA Astrophysics Data System (ADS)

Li, H. J.; Wei, F. S.; Feng, X. S.; Xie, Y. Q.

2008-09-01

This paper investigates methods to improve the predictions of Shock Arrival Time (SAT) of the original Shock Propagation Model (SPM). According to the classical blast wave theory adopted in the SPM, the shock propagating speed is determined by the total energy of the original explosion together with the background solar wind speed. Noting that there exists an intrinsic limit to the transit times computed by the SPM predictions for a specified ambient solar wind, we present a statistical analysis on the forecasting capability of the SPM using this intrinsic property. Two facts about SPM are found: (1) the error in shock energy estimation is not the only cause of the prediction errors and we should not expect that the accuracy of SPM to be improved drastically by an exact shock energy input; and (2) there are systematic differences in prediction results both for the strong shocks propagating into a slow ambient solar wind and for the weak shocks into a fast medium. Statistical analyses indicate the physical details of shock propagation and thus clearly point out directions of the future improvement of the SPM. A simple modification is presented here, which shows that there is room for improvement of SPM and thus that the original SPM is worthy of further development.

Thermalization of Heavy Ions in the Solar Wind

NASA Astrophysics Data System (ADS)

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.

The Effect on the Lunar Exosphere of a Coroual Mass Ejection Passage

NASA Technical Reports Server (NTRS)

Killen, R. M.; Hurley, D. M.; Farrell, W. M.

2011-01-01

Solar wind bombardment onto exposed surfaces in the solar system produces an energetic component to the exospheres about those bodies. The solar wind energy and composition are highly dependent on the origin of the plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into their various components, we have estimated the total sputter yield for each type of solar wind. We show that the heavy ion component, especially the He++ and 0+7 can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. Folding in the flux, we compute the source rate for several species during different types of solar wind. Finally, we use a Monte Carlo model developed to simulate the time-dependent evolution of the lunar exosphere to study the sputtering component of the exosphere under the influence of a CME passage. We simulate the background exosphere of Na, K, Ca, and Mg. Simulations indicate that sputtering increases the mass of those constituents in the exosphere a few to a few tens times the background values. The escalation of atmospheric density occurs within an hour of onset The decrease in atmospheric density after the CME passage is also rapid, although takes longer than the increase, Sputtered neutral particles have a high probability of escaping the moon,by both Jeans escape and photo ionization. Density and spatial distribution of the exosphere can be tested with the LADEE mission.

A Time-dependent Heliospheric Model Driven by Empirical Boundary Conditions

NASA Astrophysics Data System (ADS)

Kim, T. K.; Arge, C. N.; Pogorelov, N. V.

2017-12-01

Consisting of charged particles originating from the Sun, the solar wind carries the Sun's energy and magnetic field outward through interplanetary space. The solar wind is the predominant source of space weather events, and modeling the solar wind propagation to Earth is a critical component of space weather research. Solar wind models are typically separated into coronal and heliospheric parts to account for the different physical processes and scales characterizing each region. Coronal models are often coupled with heliospheric models to propagate the solar wind out to Earth's orbit and beyond. The Wang-Sheeley-Arge (WSA) model is a semi-empirical coronal model consisting of a potential field source surface model and a current sheet model that takes synoptic magnetograms as input to estimate the magnetic field and solar wind speed at any distance above the coronal region. The current version of the WSA model takes the Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model as input to provide improved time-varying solutions for the ambient solar wind structure. When heliospheric MHD models are coupled with the WSA model, density and temperature at the inner boundary are treated as free parameters that are tuned to optimal values. For example, the WSA-ENLIL model prescribes density and temperature assuming momentum flux and thermal pressure balance across the inner boundary of the ENLIL heliospheric MHD model. We consider an alternative approach of prescribing density and temperature using empirical correlations derived from Ulysses and OMNI data. We use our own modeling software (Multi-scale Fluid-kinetic Simulation Suite) to drive a heliospheric MHD model with ADAPT-WSA input. The modeling results using the two different approaches of density and temperature prescription suggest that the use of empirical correlations may be a more straightforward, consistent method.

EXPERIMENTAL DETERMINATION OF WHISTLER WAVE DISPERSION RELATION IN THE SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stansby, D.; Horbury, T. S.; Chen, C. H. K.

2016-09-20

The origins and properties of large-amplitude whistler wavepackets in the solar wind are still unclear. In this Letter, we utilize single spacecraft electric and magnetic field waveform measurements from the ARTEMIS mission to calculate the plasma frame frequency and wavevector of individual wavepackets over multiple intervals. This allows direct comparison of experimental measurements with theoretical dispersion relations to identify the observed waves as whistler waves. The whistlers are right-hand circularly polarized, travel anti-sunward, and are aligned with the background magnetic field. Their dispersion is strongly affected by the local electron parallel beta in agreement with linear theory. The properties measuredmore » are consistent with the electron heat flux instability acting in the solar wind to generate these waves.« less

Solar-Planetary Relationships: Magnetospheric Physics

NASA Technical Reports Server (NTRS)

Barnes, Aaron

1979-01-01

The quadrennium 1975-1978 was a period of great advance for solar-wind studies, a period that combined exploration of new regions with increased maturity in established fields of study. The Helios, Pioneer, and Voyager spacecraft have been exploring the inner and outer regions of the solar wind. There has been a rebirth of the study of possible relations between solar variability and Earth's climate and weather, stimulated largely by Eddy's investigation of the Maunder Minimum; the solar wind may well prove to be a significant link in solar-terrestrial relations. Unique coronal data from the SKYLAB 1973-1974 mission, in combination with satellite and ground-based observations, provided the basis for identification of coronal holes as the main source of highspeed solar wind. The interplanetary medium has continued to serve as a laboratory for the study of plasma processes that cannot yet be studied in terrestrial laboratories, providing insights of potential importance both for controlled fusion research and for astrophysics. It is ironic that such a productive period, the legacy of many past space missions, was also a time of severely limited opportunity for new space investigations; the outlook for the future is equally austere. Especially regrettable is the dearth of career opportunities for young scientists in this field; comparison of the bibliography of this report with that of its predecessor 4 years ago shows few new names. Despite such problems, research has continued with enthusiasm and much has been learned. The present report will survey selected topics related to the origin, expansion, and acceleration of the solar wind and the plasma physics of the interplanetary medium. Companion reports deal with a number of closely related topics, including the heliocentric distance and latitude variation of the solar wind and its fluctuations topology of the interplanetary magnetic field morphology of solar-wind streams and shocks, sunweather studies, and interplanetary manifestations of type-3 bursts. Of the subjects that fall within the scope of this report, the study of the relationship between coronal holes and solar-wind streams, and the associated revision of our ideas about solar wind acceleration and heating, have had the most impact; hence I review these topics in considerable detail. In addition, I discuss the topics of hydromagnetic waves and turbulence, and interplanetary electrons, as items of particular importance during the past quadrennium.

Ion Acceleration by Multiple Reflections at Martian Bow Shock

NASA Astrophysics Data System (ADS)

Yamauchi, M.; Futaana, Y.; Fedorov, A.; Frahm, R. A.; Dubinin, E.; Lundin, R.; Sauvaud, J.-A.; Winningham, J. D.; Barabash, S.; Holmström, H.

2012-04-01

The ion mass analyzer (IMA) on board Mars Express revealed bundled structures of ions in the energy domain within a distance of a proton gyroradius from the Martian bow shock. Seven prominent traversals during 2005 were examined when the energy-bunched structure was observed together with pick-up ions of exospheric origin, the latter of which is used to determine the local magnetic field orientation from its circular trajectory in velocity space. These seven traversals include different bow shock configurations: (a) quasi-perpendicular shock with its specular direction of the solar wind more perpendicular to the magnetic field (QT), (b) quasi-perpendicular shock with its specular reflection direction of the solar wind more along the magnetic field (FS), and (c) quasi-parallel (QL) shock. In all seven cases, the velocity components of the energy-bunched structure are consistent with multiple specular reflections of the solar wind at the bow shock up to at least two reflections. The accelerated solar wind ions after two specular reflections have large parallel components with respect to the magnetic field for the QL shock whereas the field-aligned speed is much smaller than the perpendicular speed for the QT shock. The reflected ions escape into the solar wind when and only when the reflection is in the field-aligned direction.

X-ray Magnetosheath Emission from Solar Wind Charge Exchange During Two CME Events in 2001

NASA Astrophysics Data System (ADS)

Sembay, S.; Whittaker, I. C.; Read, A.; Carter, J. A.; Milan, S. E.; Palmroth, M.

2016-12-01

Using a combination of the GUMICS-4 MHD model and observed solar wind heavy ion abundances from ACE, we produce case studies looking at X-ray emission from charge exchange in the Earth's magnetosheath. We specifically look in the 0.5-0.7 keV range, which is dominated by highly ionised oxygen emission. Previous studies looking at solar wind charge exchange (SWCX) emission have verified our modelling process via comparison to the XMM-Newton X-ray observatory, and we use the same simulation process here. This study investigates the emission magnitude changes that occur during two coronal mass ejection (CME) events (31 March 2001 and 21 October 2001). As part of this work we also provide a novel masking technique to exclude the plasma of terrestrial origin in the MHD model. As expected the two CME cases examined provide an increased dynamic pressure which pushes the magnetopause closer to the Earth, with a high temporal variation. We show how these changes cause an increase in the peak SWCX emission signature by over an order of magnitude from the quiescent solar wind case. Imaging of this SWCX emission allows a global view of the magnetopause shape and position, a technique planned for future missions such as SMILE (Solar wind Magnetosphere Ionosphere Link Explorer).

Kinetic Properties of Solar Wind Silicon and Iron Ions

NASA Astrophysics Data System (ADS)

Janitzek, N. P.; Berger, L.; Drews, C.; Wimmer-Schweingruber, R. F.

2017-12-01

Heavy ions with atomic numbers Z>2 account for less than one percent of the solar wind ions. However, serving as test particles with differing mass and charge, they provide a unique experimental approach to major questions of solar and fundamental plasma physics such as coronal heating, the origin and acceleration of the solar wind and wave-particle interaction in magnetized plasma. Yet the low relative abundances of the heavy ions pose substantial challenges to the instrumentation measuring these species with reliable statistics and sufficient time resolution. As a consequence the numbers of independent measurements and studies are small. The Charge Time-Of-Flight (CTOF) mass spectrometer as part of the Charge, ELement and Isotope Analysis System (CELIAS) onboard the SOlar and Heliospheric Observatory (SOHO) is a linear time-of-flight mass spectrometer which was operated at Lagrangian point L1 in 1996 for a few months only, before it suffered an instrument failure. Despite its short operation time, the CTOF sensor measured solar wind heavy ions with excellent charge state separation, an unprecedented cadence of 5 minutes and very high counting statistics, exceeding similar state-of-the-art instruments by a factor of ten. In contrast to earlier CTOF studies which were based on reduced onboard post-processed data, in our current studies we use raw Pulse Height Analysis (PHA) data providing a significantly increased mass, mass-per-charge and velocity resolution. Focussing on silicon and iron ion measurements, we present an overview of our findings on (1) short time behavior of heavy ion 1D radial velocity distribution functions, (2) differential streaming between heavy ions and solar wind bulk protons, (3) kinetic temperatures of heavy ions. Finally, we compare the CTOF results with measurements of the Solar Wind Ion Composition Spectrometer (SWICS) instrument onboard the Advanced Composition Explorer (ACE).

Solar Polar ORbit Telescope (SPORT): A Potential Heliophysics Mission of China

NASA Astrophysics Data System (ADS)

Liu, Ying

We describe a spacecraft mission, named Solar Polar ORbit Telescope (SPORT), which is currently under a scientific and engineering background study in China. SPORT was originally proposed in 2004 by the National Space Science Center, Chinese Academy of Sciences. It will carry a suite of remote-sensing and in-situ instruments to observe coronal mass ejections (CMEs), solar high-latitude magnetism, and the fast solar wind from a polar orbit around the Sun. It is intended to be the first mission that carries remote-sensing instruments from a high-latitude orbit around the Sun and the first mission that could measure solar high-latitude magnetism. The first extended view of the polar region of the Sun and the ecliptic plane enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere and solar high-latitude magnetism giving rise to eruptions and the fast solar wind.

Relation between the electromagnetic processes in the near-Earth space and dynamics of the biological resources in Russian Arctic

NASA Astrophysics Data System (ADS)

Makarova, L. N.; Shirochkov, A. V.; Tumanov, I. L.

The start of the satellite era in the Space explorations led to new and more profound knowledge of the solar physics and the sources of its activity. From these points of view, it is worthy to examine again the relations between biological processes and the solar activity. We explore the relation between dynamics of the solar activity (including the solar wind) and changes in population of some species of Arctic fauna (lemmings, polar foxes, caribous, wolves, elks, etc.). The data include statistical rows of various lengths (30 80 years). The best correlation between two data sets is found when the solar wind dynamic pressure as well as variations of the total solar irradiance (i.e., level of the solar UV radiation) is taken as the space parameters. Probably the electromagnetic fields of space origin are an important factor determining dynamics of population of the Arctic fauna species.

Gaussianity versus intermittency in solar system plasma turbulence

NASA Astrophysics Data System (ADS)

Echim, M.

2014-12-01

Statistical properties of plasma and magnetic field fluctuations exhibit features linked with the dynamics of the targeted system and sometimes with the physical processes that are at the origin of these fluctuations. Intermittency is sometimes discussed in terms of non-Gaussianity of the Probability Distribution Functions (PDFs) of fluctuations for ranges of spatio/temporal scales. Some examples of self-similarity have been however shown for PDFs whose wings are not Gaussian. In this study we discuss intermittency in terms of non-Gaussianity as well as scale dependence of the higher order moments of PDFs, in particular the flatness. We use magnetic field and plasma data from several space missions, in the solar wind (Ulysses, Cluster, and Venus Express), and in the planetary magnetosheaths (Cluster and Venus Express). We analyze Ulysses data that satisfy a consolidated set of selection criteria able to identify "pure" fast and slow wind. We investigate Venus Express data close to the orbital apogee, in the solar wind, at 0.72 AU, and in the Venus magnetosheath. We study Cluster data in the solar wind (for time intervals not affected by planetary ions effects), and the magnetosheath. We organize our 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 PDFs obtained in the terrestrial magnetosphere, and one for the solar minimum, 2007-2008, that includes PDFs obtained in the terrestrial and Venus magnetospheres and magnetosheaths). In addition to investigating the statistical properties of fluctuations for the minimum and maximum of the solar cycle we also analyze the similarities and differences between fast and slow wind. We emphasize the importance of our data survey and analysis in the context of understanding the solar wind turbulence and complexity, and the exploitation of data bases and as a first step towards developing a (virtual) laboratory for studying solar system plasma turbulence and intermittency. Research supported by the European FP7 Programme (grant agreement 313038/STORM), and a grant of the Romanian CNCS -UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.

SWCX Emission from the Helium Focusing Cone - Preliminary Results

NASA Technical Reports Server (NTRS)

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

2008-01-01

Preliminary results from an XMM-Newton campaign to study solar wind charge exchange (SWCX) emission from the heliospheric focusing cone of interstellar helium are presented. The detections of enhanced O VII and O VIII emission from the cone are at the 2(sigma) and 4(sigma) levels. The solar wind charge exchange (SWCX) emission in the heliosphere not associated with distinct objects (e.g., comets and planets including exospheric material in and near Earth s magnetosheath) is proportional to the flux of the solar wind and the space density of neutral material. The neutral material originates in the interstellar medium (ISM) and passes through the solar system due to the relative motion of the Sun and the ISM. The flow of the neutral material through the solar system is strongly perturbed by the Sun both by gravity and by radiation pressure. Because of the relative radiative scattering cross sections and the effect of solar gravitation the density of interstellar hydrogen near the Sun is reduced while interstellar helium is gravitationally focused. This creates a helium focusing cone downstream of the Sun [e.g., 1, and references therein].

Non-Extensive Statistical Analysis of Solar Wind Electric, Magnetic Fields and Solar Energetic Particle time series.

NASA Astrophysics Data System (ADS)

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.

Measurements of electric fields in the solar wind: Interpretation difficulties

NASA Astrophysics Data System (ADS)

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dósa, M.; Erdős, G., E-mail: dosa.melinda@wigner.mta.hu

Open magnetic flux in the heliosphere is determined from the radial component of the magnetic field vector measured onboard interplanetary space probes. Previous Ulysses research has shown remarkable independence of the flux density from heliographic latitude, explained by super-radial expansion of plasma. Here we are investigating whether any longitudinal variation exists in the 50 year long OMNI magnetic data set. The heliographic longitude of origin of the plasma package was determined by applying a correction according to the solar wind travel time. Significant recurrent enhancements of the magnetic flux density were observed throughout solar cycle 23, lasting for several years.more » Similar, long-lasting recurring features were observed in the solar wind velocity, temperature and the deviation angle of the solar wind velocity vector from the radial direction. Each of the recurrent features has a recurrence period slightly differing from the Carrington rotation rate, although they show a common trend in time. Examining the coronal temperature data of ACE leads to the possible explanation that these long-term structures are caused by slow–fast solar wind interaction regions. A comparison with MESSENGER data measured at 0.5 au shows that these longitudinal magnetic modulations do not exist closer to the Sun, but are the result of propagation.« less

Measurements of electric fields in the solar wind: Interpretation difficulties

NASA Technical Reports Server (NTRS)

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.

Alfvén Turbulence Driven by High-Dimensional Interior Crisis in the Solar Wind

NASA Astrophysics Data System (ADS)

Chian, A. C.-L.; Rempel, E. L.; Macau, E. E. N.; Rosa, R. R.; Christiansen, F.

2003-09-01

Alfvén intermittent turbulence has been observed in the solar wind. It has been previously shown that the interplanetary Alfvén intermittent turbulence can appear due to a low-dimensional temporal chaos [1]. In this paper, we study the nonlinear spatiotemporal dynamics of Alfvén waves governed by the Kuramoto-Sivashinsky equation which describes the phase evolution of a large-amplitude Alfvén wave. We investigate the Alfvén turbulence driven by a high-dimensional interior crisis, which is a global bifurcation caused by the collision of a chaotic attractor with an unstable periodic orbit. This nonlinear phenomenon is analyzed using the numerical solutions of the model equation. The identification of the unstable periodic orbits and their invariant manifolds is fundamental for understanding the instability, chaos and turbulence in complex systems such as the solar wind plasma. The high-dimensional dynamical system approach to space environment turbulence developed in this paper can improve our interpretation of the origin and the nature of Alfvén turbulence observed in the solar wind.

Lunar and Planetary Science XXXV: Special Session: Oxygen in the Solar System, I

NASA Technical Reports Server (NTRS)

2004-01-01

The Special Session: Oxygen in the Solar System, I, included the following reports:Oxygen in the Solar System: Origins of Isotopic and Redox Complexity; The Origin of Oxygen Isotope Variations in the Early Solar System; Solar and Solar-Wind Oxygen Isotopes and the Genesis Mission; Solar 18O/17O and the Setting for Solar Birth; Oxygen Isotopes in Early Solar System Materials: A Perspective Based on Microbeam Analyses of Chondrules from CV Carbonaceous Chondrites; Insight into Primordial Solar System Oxygen Reservoirs from Returned Cometary Samples; Tracing Meteorites to Their Sources Through Asteroid Spectroscopy; Redox Conditions Among the Terrestrial Planets; Redox Complexity in Martian Meteorites: Implications for Oxygen in the Terrestrial Planets; Implications of Sulfur Isotopes for the Evolution of Atmospheric Oxygen; Oxygen in the Outer Solar System; and On the Oxidation States of the Galilean Satellites: Implications for Internal Structures.

Observational Evidence for the Associated Formation of Blobs and Raining Inflows in the Solar Corona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez-Diaz, E.; Rouillard, A. P.; Lavraud, B.

The origin of the slow solar wind is still a topic of much debate. The continual emergence of small transient structures from helmet streamers is thought to constitute one of the main sources of the slow wind. Determining the height at which these transients are released is an important factor in determining the conditions under which the slow solar wind forms. To this end, we have carried out a multipoint analysis of small transient structures released from a north–south tilted helmet streamer into the slow solar wind over a broad range of position angles during Carrington Rotation 2137. Combining themore » remote-sensing observations taken by the Solar-TErrestrial RElations Observatory ( STEREO ) mission with coronagraphic observations from the SOlar and Heliospheric Observatory ( SOHO ) spacecraft, we show that the release of such small transient structures (often called blobs), which subsequently move away from the Sun, is associated with the concomitant formation of transient structures collapsing back toward the Sun; the latter have been referred to by previous authors as “raining inflows.” This is the first direct association between outflowing blobs and raining inflows, which locates the formation of blobs above the helmet streamers and gives strong support that the blobs are released by magnetic reconnection.« less

Kinetic Modeling of the Lunar Dust-Plasma Environment

NASA Astrophysics Data System (ADS)

Kallio, Esa; Alho, Markku; Alvarez, Francisco; Barabash, Stas; Dyadechkin, Sergey; Fernandes, Vera; Futaana, Yoshifumi; Harri, Ari-Matti; Haunia, Touko; Heilimo, Jyri; Holmström, Mats; Jarvinen, Riku; Lue, Charles; Makela, Jakke; Porjo, Niko; Schmidt, Walter; Shahab, Fatemi; Siili, Tero; Wurz, Peter

2014-05-01

Modeling of the lunar dust and plasma environment is a challenging task because a self-consistent model should include ions, electrons and dust particles and numerous other factors. However, most of the parameters are not well established or constrained by measurements in the lunar environment. More precisely, a comprehensive model should contain electrons originating from 1) the solar wind, 2) the lunar material (photoelectrons, secondary electrons) and 3) the lunar dust. Ions originate from the solar wind, the lunar material, the lunar exosphere and the dust. To model the role of the dust in the lunar plasma environment is a highly complex task since the properties of the dust particles in the exosphere are poorly known (e.g. mass, size, shape, conductivity) or not known (e.g. charge and photoelectron emission) and probably are time dependent. Models should also include the effects of interactions between the surface and solar wind and energetic particles, and micrometeorites. Largely different temporal and spatial scales are also a challenge for the numerical models. In addition, the modeling of a region on the Moon - for example on the South Pole - at a given time requires also knowledge of the solar illumination conditions at that time, mineralogical and electric properties of the local lunar surface, lunar magnetic anomalies, solar UV flux and the properties of the solar wind. Harmful effects of lunar dust to technical devices and to human health as well as modeling of the properties of the lunar plasma and dust environment have been topics of two ESA funded projects L-DEPP and DPEM. In the presentation we will summarize some basic results and characteristics of plasma and fields near and around the Moon as studied and discovered in these projects. Especially, we analyse three different space and time scales by kinetic models: [1] the "microscale" region near surface with an electrostatic PIC (ions and electrons are particles) model, [2] the "mesoscale" region including lunar magnetic anomalies and [3] the global scale Moon-solar wind interaction with hybrid (ions as particles in massless electron fluid) models.

Simultaneous disappearances of plasmaspheric hiss, exohiss, and chorus waves triggered by a sudden decrease in solar wind dynamic pressure

DOE PAGES

Liu, Nigang; Su, Zhenpeng; Gao, Zhonglei; ...

2016-12-29

Magnetospheric whistler mode waves are of great importance in the radiation belt electron dynamics. In this paper, on the basis of the analysis of a rare event with the simultaneous disappearances of whistler mode plasmaspheric hiss, exohiss, and chorus triggered by a sudden decrease in the solar wind dynamic pressure, we provide evidences for the following physical scenarios: (1) nonlinear generation of chorus controlled by the geomagnetic field inhomogeneity, (2) origination of plasmaspheric hiss from chorus, and (3) leakage of plasmaspheric hiss into exohiss. Finally, following the reduction of the solar wind dynamic pressure, the dayside geomagnetic field configuration withmore » the enhanced inhomogeneity became unfavorable for the generation of chorus, and the quenching of chorus directly caused the disappearances of plasmaspheric hiss and then exohiss.« less

Simultaneous disappearances of plasmaspheric hiss, exohiss, and chorus waves triggered by a sudden decrease in solar wind dynamic pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Nigang; Su, Zhenpeng; Gao, Zhonglei

Magnetospheric whistler mode waves are of great importance in the radiation belt electron dynamics. In this paper, on the basis of the analysis of a rare event with the simultaneous disappearances of whistler mode plasmaspheric hiss, exohiss, and chorus triggered by a sudden decrease in the solar wind dynamic pressure, we provide evidences for the following physical scenarios: (1) nonlinear generation of chorus controlled by the geomagnetic field inhomogeneity, (2) origination of plasmaspheric hiss from chorus, and (3) leakage of plasmaspheric hiss into exohiss. Finally, following the reduction of the solar wind dynamic pressure, the dayside geomagnetic field configuration withmore » the enhanced inhomogeneity became unfavorable for the generation of chorus, and the quenching of chorus directly caused the disappearances of plasmaspheric hiss and then exohiss.« less

Light element geochemistry of the Apollo 16 site

NASA Technical Reports Server (NTRS)

Kerridge, J. F.; Kaplan, I. R.; Petrowski, C.; Chang, S.

1975-01-01

The abundance and isotopic composition of carbon, sulfur, and nitrogen, the abundance of helium and hydrogen, and the content of metallic iron are reported for lunar surface samples from the Apollo 16 landing site at Cayley-Descartes. The light elements show marked interstation variability at the site. The abundances in soils of C, N, He, and H are apparently controlled mainly by exposure to the solar wind, through implantation or stripping processes. Carbon abundances (but not observed isotopic distributions) are compatible with a model in which equilibrium is established after 10,000-100,000 yr between solar wind input and loss by proton stripping. Sulfur abundances in soils are apparently controlled by abundances in local country rocks, but the lunar S cycle is quite complex. A metallic iron component may have originated by solar wind reduction of lunar Fe(2+).

Tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control

NASA Astrophysics Data System (ADS)

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.

Probing the Martian Exosphere and Neutral Escape Using Pickup Ions Measured by MAVEN

NASA Astrophysics Data System (ADS)

Rahmati, A.; Larson, D. E.; Cravens, T.; Halekas, J. S.; Lillis, R. J.; McFadden, J. P.; Mitchell, D. L.; Thiemann, E.; Connerney, J. E. P.; Dunn, P.; DiBraccio, G. A.; Espley, J. R.; Eparvier, F. G.; Jakosky, B. M.

2016-12-01

Soon after the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft started orbiting Mars in September 2014, the SEP (Solar Energetic Particle), SWIA (Solar Wind Ion Analyzer), and STATIC (Supra-Thermal and Thermal Ion Composition) instruments onboard the spacecraft started detecting planetary pickup ions. SEP can measure energetic (>50 keV) oxygen pickup ions, the source of which is the extended hot oxygen exosphere of Mars. Model results show that these pickup ions originate from tens of Martian radii upstream of Mars and are energized by the solar wind motional electric field as they gyrate back towards Mars. SEP is blind to pickup hydrogen, as the low energy threshold for detection of hydrogen in SEP is 20 keV; well above the maximum pickup hydrogen energy, which is four times the solar wind proton energy. SWIA and STATIC, on the other hand, can detect both pickup oxygen and pickup hydrogen with energies below 30 keV and created closer to Mars. During the times when MAVEN is outside the Martian bow shock and in the upstream undisturbed solar wind, the solar wind velocity measured by SWIA and the solar wind (or interplanetary) magnetic field measured by the MAG (magnetometer) instrument can be used to model pickup oxygen and hydrogen fluxes near Mars. Solar wind flux measurements of the SWIA instrument are used in calculating charge-exchange frequencies, and data from the EUVM (Extreme Ultraviolet Monitor) and SWEA (Solar Wind Electron Analyzer) instruments are also used in calculating photo-ionization and electron impact frequencies of neutral species in the Martian exosphere. By comparing SEP, SWIA, and STATIC measured pickup ion fluxes with model results, the Martian thermal hydrogen and hot oxygen neutral densities can be probed outside the bow shock, which would place constraints on estimates of oxygen and hydrogen neutral escape rates. We will present model-data comparisons of pickup ions measured outside the Martian bow shock. Our analysis reveals an order of magnitude density change with Mars season in the hydrogen exosphere, whereas the hot oxygen exosphere densities vary less than a factor of 2.

Is the S-Web the Secret to Observed Heliospheric Particle Distributions?

NASA Astrophysics Data System (ADS)

Higginson, A. K.; Antiochos, S. K.; DeVore, C. R.; Daldorff, L. K. S.; Wyper, P. F.; Ukhorskiy, A. Y.; Sorathia, K.

2017-12-01

Particle transport in the heliosphere remains an unsolved problem across energy regimes. Observations of slow solar wind show that plasma escapes from the closed-field corona, but ends up far away from the heliospheric current sheet, even though the release mechanisms are expected to occur at the HCS. Similarly, some impulsive SEP events have extreme longitudinal extents of 100 degrees or more. Recent theoretical and numerical work has shown that interchange reconnection near a coronal-hole corridor can release plasma from originally closed magnetic field lines into a large swath spread across the heliosphere, forming what is known as an S-Web arc. This is a promising mechanism for explaining both the slow solar wind, with its large latitudinal extent, and impulsive SEP particles, with their large longitudinal extent. Here we compute, for the first time, the dynamics of the S-Web when the photospheric driver is applied over a large portion of the solar surface compared to the scale of the driving. We examine the time scales for the interchange reconnection and compute the angular extent of the plasma released, in the context of understanding both the slow solar wind and flare-accelerated SEPs. We will make predictions for Solar Orbiter and Parker Solar Probe and discuss how these new measurements will help to both pinpoint the source of the slow solar wind and illuminate the transport mechanisms of wide-spread impulsive SEP events.

Low Energy Electrons in the Mars Plasma Environment

NASA Technical Reports Server (NTRS)

Link, Richard

2001-01-01

The ionosphere of Mars is rather poorly understood. The only direct measurements were performed by the Viking 1 and 2 landers in 1976, both of which carried a Retarding Potential Analyzer. The RPA was designed to measure ion properties during the descent, although electron fluxes were estimated from changes in the ion currents. Using these derived low-energy electron fluxes, Mantas and Hanson studied the photoelectron and the solar wind electron interactions with the atmosphere and ionosphere of Mars. Unanswered questions remain regarding the origin of the low-energy electron fluxes in the vicinity of the Mars plasma boundary. Crider, in an analysis of Mars Global Surveyor Magnetometer/Electron Reflectometer measurements, has attributed the formation of the magnetic pile-up boundary to electron impact ionization of exospheric neutral species by solar wind electrons. However, the role of photoelectrons escaping from the lower ionosphere was not determined. In the proposed work, we will examine the role of solar wind and ionospheric photoelectrons in producing ionization in the upper ionosphere of Mars. Low-energy (< 4 keV) electrons will be modeled using the two-stream electron transport code of Link. The code models both external (solar wind) and internal (photoelectron) sources of ionization, and accounts for Auger electron production. The code will be used to analyze Mars Global Surveyor measurements of solar wind and photoelectrons down to altitudes below 200 km in the Mars ionosphere, in order to determine the relative roles of solar wind and escaping photoelectrons in maintaining plasma densities in the region of the Mars plasma boundary.

Dissipation of Alfven Waves at Fluid Scale through Parametric Decay Instabilities in Low-beta Turbulent Plasma

NASA Astrophysics Data System (ADS)

Fu, X.; Li, H.; Guo, F.; Li, X.; Roytershteyn, V.

2017-12-01

The solar wind is a turbulent magnetized plasma extending from the upper atmosphere of the sun to the edge of the heliosphere. It carries charged particles and magnetic fields originated from the Sun, which have great impact on the geomagnetic environment and human activities in space. In such a magnetized plasma, Alfven waves play a crucial role in carrying energy from the surface of the Sun, injecting into the solar wind and establishing power-law spectra through turbulent energy cascades. On the other hand, in compressible plasmas large amplitude Alfven waves are subject to a parametric decay instability (PDI) which converts an Alfven wave to another counter-propagating Alfven wave and an ion acoustic wave (slow mode). The counter-propagating Alfven wave provides an important ingredient for turbulent cascade, and the slow-mode wave provides a channel for solar wind heating in a spatial scale much larger than ion kinetic scales. Growth and saturation of PDI in quiet plasma have been intensively studied using linear theory and nonlinear simulations in the past. Here using 3D hybrid simulations, we show that PDI is still effective in turbulent low-beta plasmas, generating slow modes and causing ion heating. Selected events in WIND data are analyzed to identify slow modes in the solar wind and the role of PDI, and compared with our simulation results. We also investigate the validity of linear Vlasov theory regarding PDI growth and slow mode damping in turbulent plasmas. Since PDI favors low plasma beta, we expect to see more evidence of PDI in the solar wind close to the Sun, especially from the upcoming NASA's Parker Solar Probe mission which will provide unprecedented wave and plasma data as close as 8.5 solar radii from the Sun.

Clues in the rare gas isotopes to early solar system history

NASA Technical Reports Server (NTRS)

Reynolds, J. H.

1974-01-01

Rare gases in meteorites and lunar samples are discussed stimulating the discovery of the solar wind. Radioactive isotopes are examined, making a correlation to the origin of the solar system. It is shown that the heights of the peaks above the horizontal lines represent the spectrum of the fissiogenic sample. Nuclear tracks of iodine, xenon, and plutonium detected in lunar rocks are also explained.

Moderate Geomagnetic Storms: Interplanetary Origins and Coupling Functions (ISEE3 Data)

NASA Technical Reports Server (NTRS)

Mendes, Odim, Jr.; Gonzalez, W. D.; Gonzalez, A. L. C.; Pinto, O., Jr.; Tsurutani, B. T.

1996-01-01

Geomagnetic storms are related to the ring current intensification, which is driven by energy injection primarily during energetic solar wind-magnetosphere coupling due to reconnection at the magnetopause. This work identified the interplanetary origins of moderate geomagnetic storms (-100nT is less or equal to Dst(sub peak) is less than or equal to -50 nT) and analyzed the coupling processes during the storm main phase at solar maximum (1978-1979).

Intermittent nature of solar wind turbulence near the Earth's bow shock: phase coherence and non-Gaussianity.

PubMed

Koga, D; Chian, A C-L; Miranda, R A; Rempel, E L

2007-04-01

The link between phase coherence and non-Gaussian statistics is investigated using magnetic field data observed in the solar wind turbulence near the Earth's bow shock. The phase coherence index Cphi, which characterizes the degree of phase correlation (i.e., nonlinear wave-wave interactions) among scales, displays a behavior similar to kurtosis and reflects a departure from Gaussianity in the probability density functions of magnetic field fluctuations. This demonstrates that nonlinear interactions among scales are the origin of intermittency in the magnetic field turbulence.

Solar wind noble gases and nitrogen in metal from lunar soil 68501

NASA Technical Reports Server (NTRS)

Becker, Richard H.; Pepin, Robert O.

1994-01-01

Noble gases and N were analyzed in handpicked metal separates from lunar soil 68501 by a combination of step-wise combustions and pyrolyses. Helium and Ne were found to be unfractionated with respect to one another when normalized to solar abundances, for both the bulk sample and for all but the highest temperature steps. However, they are depleted relative to Ar, Kr and Xe by at least a factor of 5. The heavier gases exhibit mass-dependent fractionation relative to solar system abundance ratios but appear unfractionated, both in the bulk metal and in early temperature steps, when compared to relative abundances derived from lunar ilmenite 71501 by chemical etching, recently put forward as representing the abundance ratios in solar wind. Estimates of the contribution of solar energetic particles (SEP) to the originally implanted solar gases, derived from a basic interpretation of He and Ne isotopes, yield values of about 10%. Analysis of the Ar isotopes requires a minimum of 20% SEP, and Kr isotopes, using our preferred composition for solar wind Kr, yield a result that overlaps both these values. It is possible to reconcile the data from these gases if significant loss of solar wind Ar, Kr and presumably Xe has occurred relative to the SEP component, most likely by erosive processes that are mass independent, although mass-dependent losses (Ar greater than Kr greater than Xe) cannot be excluded. If such losses did occur, the SEP contribution to the solar implanted gases must have been no more than a few percent. Nitrogen is a mixture of indigenous meteoritic N, whose isotopic composition is inferred to be relatively light, and implanted solar N, which has probably undergone diffusive redistribution and fractionation. If the heavy noble gases have not undergone diffusive loss, then N/Ar in the solar wind can be inferred to be at least several times the accepted solar ratio. The solar wind N appears, even after correction for fractionation effects, to have a minimum delta N-15 value equal to or greater than +150% and a more probable value equal to or greater than +200%.

Implementation and Verification of the Chen Prediction Technique for Forecasting Large Nonrecurrent Storms*

NASA Astrophysics Data System (ADS)

Arge, C. N.; Chen, J.; Slinker, S.; Pizzo, V. J.

2000-05-01

The method of Chen et al. [1997, JGR, 101, 27499] is designed to accurately identify and predict the occurrence, duration, and strength of largegeomagnetic storms using real-time solar wind data. The method estimates the IMF and the geoeffectiveness of the solar wind upstream of a monitor and can provide warning times that range from a few hours to more than 10 hours. The model uses physical features of solar wind structures that cause large storms: long durations of southward interplanetary magnetic field. It is currently undergoing testing, improvement, and validation at NOAA/SEC in effort to transition it into a real-time space weather forecasting tool. The original version of the model has modified so that it now makes hourly (as opposed to daily) predictions and has been improved in effort to enhance both its predictive capability and reliability. In this paper, we report on the results of a 2-year historical verification study of the model using ACE real-time data. The prediction performances of the original and improved versions of the model are then compared. A real-time prediction web page has been developed and is on line at NOAA/SEC. *Work supported by ONR.

Study on field-aligned electrons with Cluster observation in the Earth's cusp

NASA Astrophysics Data System (ADS)

Shi, Jiankui; Torkar, Klaus; Cheng, Zhengwei

2017-04-01

Cusp region is very important to the solar wind-magnetosphere coupling. The solar wind particles, through the cusp, can directly entry into the magnetosphere and ionosphere, and transport the mass, momentum and energy. The gyrating charged particles with field-aligned velocity are significant to perform the transportation. In this study, data from Cluster observation are used to study the characteristics of field-aligned electrons (FAE's) including the downward and the upward FAEs in the cusp. We select FAE event to do analysis. The durations of the FAE event covered a wide range from 6 to 475 seconds. The FAE's were found to occur very commonly in a circumpolar zone in the polar region and the MLT and ILAT distributions showed that most of the FAE events were observed around the cusp (70-80°ILAT, 0900-1500MLT). With the FAE flux the contribution of the electrons to the Field-Aligned Current (FAC) is estimated and the result shows that the FAE was the main carrier to the FAC in the cusp. The physical mechanisms of the FAE are analyzed, namely that the downward electrons were mainly from the solar wind and the upward electrons may originated from accelerated ionospheric up-flowing electrons or mirrored solar wind electrons. The energy transportation into the magnetosphere by the solar wind electrons through the cusp is also investigated.

Analysis of data from LEND instrument on LRO: May water deposits be expected on poles of Mercury?

NASA Astrophysics Data System (ADS)

Mitrofanov, I.

2012-04-01

Lunar Exploration Neutron Detector (LEND) of LRO measured the flux of epithermal neutrons with high spatial resolution ˜10 km for the amplitude of 50 km. The LEND data from the polar caps above 80° latitude were tested for the presence of local spots of epithermal Neutron Suppression Regions (NSRs), which have been identified with wa-ter ice permafrost. The model has been proposed, which explains the origin of water at lunar poles by chemical reactions between hydrogen of solar wind with oxygen of lunar regolith. The so-called solar water could be produced under the sunlit surface, and than migrate either at cold traps in he local vicinity from the irradiated spot of origin, or at cold subsur-face layer just below of the uppermost layer of origin. Similarly to the Moon, there are data of radio sensing of Mercury, which points out that this planet might have the water ice deposits at poles. Therefore, one may suspect that the main physics could also be similar at poles of the Moon and the Mercury: - if the water ice deposits are on the lunar poles, they should be at the Hermean poles as well; - if comets are not the main source for the water at lunar poles, they should not also be the main source for the polar water deposits on the Mercury. However, one should also take into account that the Moon and the Mercury have rather different physics of inter-action between the plasma of solar wind and the surface: - the Mercury have the dipole magnetic field, which is large enough to shield the equatorial belt of the planet from the direct interaction with the plasma of solar wind; - flux of solar wind and solar radiation at the orbit of Mercury are much larger than they are at the Earth orbit; - the average temperature of illuminated spots at Hermean poles is much larger than the temperature of illuminated spots at poles of the Moon. In addition to current neutron data from LRO, the data from MESSENGER should be studied for better under-standing of polar water ice deposits at the Moon and at the Mercury. Additional data will be provided by neutron mapping from the BeppiColombo spacecraft, which will map neutron albedo of bother Hermean poles (the MESSENGER maps only the southern hemisphere). First of all, one have to test that Mercury have extended suppression regions of epithermal neutrons around both poles, as the Moon has. If hydrogen at polar regolith is delivered by the solar wind, the polar suppression of Mercury should be rather different from one of the Moon, because Hermean magnetosphere should chanelize the plasma of solar wind plasma toward the poles. Second, one have to test the presence of local NSEs at the Hermean poles and to compare them with the lunar NSRs. If NSRs at both celestial bodies are associated with deposits of solar water, one could expect to find more water rich permafrost on the Mercury than on the Moon at areas with similarly cold surfaces, because at the same thermal conditions production rate of water molecules from the solar wind should be higher on Mercury than on the Moon.

A solar cycle dependence of nonlinearity in magnetospheric activity

NASA Astrophysics Data System (ADS)

Johnson, Jay R.; Wing, Simon

2005-04-01

The nonlinear dependencies inherent to the historical Kp data stream (1932-2003) are examined using mutual information and cumulant-based cost as discriminating statistics. The discriminating statistics are compared with surrogate data streams that are constructed using the corrected amplitude adjustment Fourier transform (CAAFT) method and capture the linear properties of the original Kp data. Differences are regularly seen in the discriminating statistics a few years prior to solar minima, while no differences are apparent at the time of solar maxima. These results suggest that the dynamics of the magnetosphere tend to be more linear at solar maximum than at solar minimum. The strong nonlinear dependencies tend to peak on a timescale around 40-50 hours and are statistically significant up to 1 week. Because the solar wind driver variables, VBs, and dynamical pressure exhibit a much shorter decorrelation time for nonlinearities, the results seem to indicate that the nonlinearity is related to internal magnetospheric dynamics. Moreover, the timescales for the nonlinearity seem to be on the same order as that for storm/ring current relaxation. We suggest that the strong solar wind driving that occurs around solar maximum dominates the magnetospheric dynamics, suppressing the internal magnetospheric nonlinearity. On the other hand, in the descending phase of the solar cycle just prior to solar minimum, when magnetospheric activity is weaker, the dynamics exhibit a significant nonlinear internal magnetospheric response that may be related to increased solar wind speed.

The Interplanetary and Magnetospheric Causes of Extreme DB/dt at Equatorial Locations

NASA Technical Reports Server (NTRS)

Adebesin, Babatunde O.; Pulkkinen, Antti; Ngwira, Chigomezyo M.

2016-01-01

The 1 min resolution solar wind and geomagnetic data obtained from seven equatorial low-latitude stations during four extreme geomagnetic activities are used to investigate the extreme dB/dt perturbations. Simulations of the magnetospheric-ionospheric environment were also performed for varying amplitudes of the solar proton density. Simulations were carried out using the Space Weather Modeling Framework BATS-R-US + RCM model. Both the observations and simulations demonstrated that the appearance time of the extreme dB/dt perturbations at equatorial stations during disturbed conditions is instantaneous and equitable to those experienced at auroral regions yielding time lags of the order of a few seconds. We find that the rapid dB/dt enhancements are caused by the electric field of magnetospheric current origin, which is being enhanced by solar wind density and ram pressure variations and boosted by the equatorial electro jet. Our results indicate that the solar wind proton density variations could be used as a predictor of extreme dB/dt enhancement at equatorial latitudes.

The interplanetary and magnetospheric causes of extreme dB/dt at equatorial locations

NASA Astrophysics Data System (ADS)

Adebesin, Babatunde O.; Pulkkinen, Antti; Ngwira, Chigomezyo M.

2016-11-01

The 1 min resolution solar wind and geomagnetic data obtained from seven equatorial/low-latitude stations during four extreme geomagnetic activities are used to investigate the extreme dB/dt perturbations. Simulations of the magnetospheric-ionospheric environment were also performed for varying amplitudes of the solar proton density. Simulations were carried out using the Space Weather Modeling Framework/BATS-R-US + RCM model. Both the observations and simulations demonstrated that the appearance time of the extreme dB/dt perturbations at equatorial stations during disturbed conditions is instantaneous and equitable to those experienced at auroral regions yielding time lags of the order of a few seconds. We find that the rapid dB/dt enhancements are caused by the electric field of magnetospheric current origin, which is being enhanced by solar wind density and ram pressure variations and boosted by the equatorial electrojet. Our results indicate that the solar wind proton density variations could be used as a predictor of extreme dB/dt enhancement at equatorial latitudes.

KSC-97PC904

NASA Image and Video Library

1997-06-16

Workers in the Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2) begin prelaunch processing of the Advanced Composition Explorer (ACE) which will investigate the origin and evolution of solar phenomenon, the formation of the solar corona, solar flares and the acceleration of the solar wind. ACE was built for NASA by the Johns Hopkins Applied Physics Laboratory. The spacecraft is scheduled to be launched Aug. 21 aboard a two-stage Delta II 7920-8 rocket from Space Launch Complex 17, Pad A

KSC-97PC905

NASA Image and Video Library

1997-06-16

Prelaunch processing begins on the Advanced Composition Explorer (ACE) spacecraft in the Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2). ACE will investigate the origin and evolution of solar phenomenon, the formation of the solar corona, solar flares and the acceleration of the solar wind. ACE was built for NASA by the Johns Hopkins Applied Physics Laboratory. The spacecraft is scheduled to be launched Aug. 21 aboard a two-stage Delta II 7920-8 rocket from Space Launch Complex 17, Pad A

MESSENGER and Venus Express Observations of the Near-tail of Venus: Magnetic Flux Transport, Current Sheet Structure, and Flux Rope Formation

NASA Technical Reports Server (NTRS)

Slavin, James A.; Boardsen, S. A.; Sarantos, M.; Acuna, M. H.; Anderson, B. J.; Barabash, S.; Benna, M.; Fraenz, M.; Gloeckler, G.; Gold, R. E.;

The Structure and Dynamics of the Corona - Heliosphere Connection

NASA Technical Reports Server (NTRS)

Antiochos, Spiro K.; Linker, Jon A.; Lionello, Roberto; Mikic, Zoran; Titov, Viacheslav; Zurbuchen, Thomas H.

2011-01-01

Determining the source at the Sun of the slow solar wind is one of the major unsolved problems in solar and heliospheric physics. First, we review the existing theories for the slow wind and argue that they have difficulty accounting for both the observed composition of the wind and its large angular extent. A new theory in which the slow wind originates from the continuous opening and closing of narrow open field corridors, the S-Web model, is described. Support for the S-Web model is derived from MHD solutions for the quasisteady corona and wind during the time of the August 1, 2008 eclipse. Additionally, we perform fully dynamic numerical simulations of the corona and heliosphere in order to test the S-Web model as well as the interchange model proposed by Fisk and co-workers. We discuss the implications of our simulations for the competing theories and for understanding the corona - heliosphere connection, in general.

The Structure and Dynamics of the Corona - Heliosphere Connection

NASA Technical Reports Server (NTRS)

Antiochos, Spiro K.; Linker, Jon A.; Lionello, Roberto; Mikic, Zoran; Titov, Viacheslav; Zurbuchen, Thomas H.

2010-01-01

Determining the source at the Sun of the slow solar wind is one of the major unsolved problems in solar and heliospheric physics. First, we review the existing theories for the slow wind and argue that they have difficulty accounting for both the observed composition of the wind and its large angular extent. A new theory in which the slow wind originates from the continuous opening and closing of narrow open field corridors, the S-Web model, is described. Support for the S-Web model is derived from MHD solutions for the quasisteady corona and wind during the time of the August 1, 2008 eclipse. Additionally, we perform fully dynamic numerical simulations of the corona and heliosphere in order to test the S-Web model as well as the interchange model proposed by Fisk and co-workers. We discuss the implications of our simulations for the competing theories and for understanding the corona - heliosphere connection, in general.

Solar wind classification from a machine learning perspective

NASA Astrophysics Data System (ADS)

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.

Spectral Anisotropy of Magnetic Field Fluctuations around Ion Scales in the Fast Solar Wind

NASA Astrophysics Data System (ADS)

Wang, X.; Tu, C.; He, J.; Marsch, E.; Wang, L.

2016-12-01

The power spectra of magnetic field at ion scales are significantly influenced by waves and structures. In this work, we study the ΘRB angle dependence of the contribution of waves on the spectral index of the magnetic field. Wavelet technique is applied to the high time-resolution magnetic field data from WIND spacecraft measurements in the fast solar wind. It is found that around ion scales, the parallel spectrum has a slope of -4.6±0.1 originally. When we remove the waves, which correspond to the data points with relatively larger value of magnetic helicity, the parallel spectrum gets shallower gradually to -3.2±0.2. However, the perpendicular spectrum does not change significantly during the wave-removal process, and its slope remains -3.1±0.1. It means that when the waves are removed from the original data, the spectral anisotropy gets weaker. This result may help us understand the physical nature of the spectral anisotropy around the ion scales.

A new method of presentation the large-scale magnetic field structure on the Sun and solar corona

NASA Technical Reports Server (NTRS)

Ponyavin, D. I.

1995-01-01

The large-scale photospheric magnetic field, measured at Stanford, has been analyzed in terms of surface harmonics. Changes of the photospheric field which occur within whole solar rotation period can be resolved by this analysis. For this reason we used daily magnetograms of the line-of-sight magnetic field component observed from Earth over solar disc. We have estimated the period during which day-to-day full disc magnetograms must be collected. An original algorithm was applied to resolve time variations of spherical harmonics that reflect time evolution of large-scale magnetic field within solar rotation period. This method of magnetic field presentation can be useful enough in lack of direct magnetograph observations due to sometimes bad weather conditions. We have used the calculated surface harmonics to reconstruct the large-scale magnetic field structure on the source surface near the sun - the origin of heliospheric current sheet and solar wind streams. The obtained results have been compared with spacecraft in situ observations and geomagnetic activity. We tried to show that proposed technique can trace shon-time variations of heliospheric current sheet and short-lived solar wind streams. We have compared also our results with those obtained traditionally from potential field approximation and extrapolation using synoptic charts as initial boundary conditions.

BIDIRECTIONAL FLUXES OF NEARLY RELATIVISTIC ELECTRONS DURING THE ONSET OF SOLAR ENERGETIC PARTICLE EVENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, L. P.; Li, C., E-mail: pmo_sunlp@msn.com

2013-03-10

We report intensity and anisotropy measurements of energetic electrons in the energy range of {approx}27-{approx}500 keV as observed with the Wind and Advanced Composition Explorer (ACE) spacecraft in 2000 June for several solar energetic particle (SEP) events. The solar sources of the SEP events are inferred from observations from the Solar and Heliospheric Observatory spacecraft. All of the events originate from the western limb active regions (ARs), which are well connected by interplanetary magnetic field (IMF) lines linking the Sun to near-Earth space. The observations on board Wind show bimodal pitch angle distributions (PADs), whereas ACE shows PADs with onemore » peak, as is usually observed for impulsive injection of electrons at the Sun. During the time of observations, Wind was located, upstream of the Earth's bow shock in the dawn-noon sector, at distances of {approx}40-{approx}80 R{sub E} from the Earth, and we infer that it was magnetically connected to the quasi-parallel bow shock. Meanwhile, ACE, orbiting the Sun-Earth libration point L1, was not connected to the bow shock. The electron intensity-time profiles and the energy spectra show that the backstreaming electrons observed at Wind are not of magnetospheric origin. The observations suggest rather that the bidirectional electron fluxes are due to reflection or scattering by an obstacle located at a distance of less than {approx}150 R{sub E} in the anti-sunward direction, which is compatible with the obstacle being the Earth's bow shock or magnetosheath.« less

Helium and neon isotopes in the mantle: constraints on the origin of volatiles on Earth

NASA Astrophysics Data System (ADS)

Moreira, M. A.

2005-12-01

It is now obvious that the mantle neon is solar-like. The possibility that the origin of this solar flavor is due to incorporation of irradiated parent bodies during accretion (e.g. gas rich meteorites) has been evoked by Trieloff and collaborators. The main argument is the fact there are no precise 20Ne/22Ne measured ratios above 13 in oceanic basalts, whereas the solar wind has a 20Ne/22Ne of 13.8 and the "neon B" neon shows a ratio of 12.6-12.8. The second argument for an irradiated origin is the air-like 38Ar/36Ar in mantle-derived samples (the "neon B" argon is close to air), distinct from the solar argon. Here we present another argument for an irradiated origin of the rare gases in the Earth. The global correlation in oceanic basalts (MORB and OIB) between 4He/3He and 21Ne/22Ne (corrected for air contamination) gives a mixing hyperbolae with a r parameter (r=(3He/22Ne)MORB/(3He/22Ne)PM) close to 10. It is now clear that 3He/22Ne ratio in the MORB source is around 7, giving for the primitive mantle (PM) a 3He/22Ne of 0.7. The solar 3He/22Ne ratio is estimated at 5-6 whereas the gas rich meteorites show a ratio of 0.3. Therefore, the global correlation in oceanic basalts between the helium and neon isotopic ratios suggests that (some) parent bodies of the Earth were gas rich meteorites, irradiated by an energetic solar wind during the planetary accretion.

SUPRATHERMAL SOLAR WIND ELECTRONS AND LANGMUIR TURBULENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Understanding the Global Structure and Evolution of Coronal Mass Ejections in the Solar Wind

NASA Technical Reports Server (NTRS)

Riley, Pete

2004-01-01

This report summarizes the technical progress made during the first six months of the second year of the NASA Living with a Star program contract Understanding the global structure and evolution of coronal mass ejections in the solar wind, between NASA and Science Applications International Corporation, and covers the period November 18, 2003 - May 17,2004. Under this contract SAIC has conducted numerical and data analysis related to fundamental issues concerning the origin, intrinsic properties, global structure, and evolution of coronal mass ejections in the solar wind. During this working period we have focused on a quantitative assessment of 5 flux rope fitting techniques. In the following sections we summarize the main aspects of this work and our proposed investigation plan for the next reporting period. Thus far, our investigation has resulted in 6 refereed scientific publications and we have presented the results at a number of scientific meetings and workshops.

Soft X-ray study of solar wind charge exchange from the Earth's magnetosphere : Suzaku observations and a future X-ray imaging mission concept

NASA Astrophysics Data System (ADS)

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, Ishikawa et al. have conducted the systematic search of the Suzaku's 6 years archival data for the SWCX events. From ~2000 data sets, ~40 showed correlations between the X-ray light curve and solar wind flux. The SWCX emissivity is calculated in each observation by normalizing the observed X-ray flux by the solar wind flux observed as ACE and WIND, and is discussed in the context of the exospheric neutral distribution and magnetospheric structure. These soft X-ray studies with Earth-orbiting satellites are now leading X-ray astronomers and space plasma physicists to propose an X-ray imaging mission of the Earth's magnetosphere. Soft X-ray imaging from high altitude (e.g., the Moon orbit) offers the capability of mapping plasma structures at <0.1 Re scale and time cadence at

Nature of Kinetic Scale Fluctuations in Solar Wind Turbulence

NASA Astrophysics Data System (ADS)

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.

Saturation of the Electric Field Transmitted to the Magnetosphere

NASA Technical Reports Server (NTRS)

Lyatsky, Wladislaw; Khazanov, George V.; Slavin, James A.

2010-01-01

We reexamined the processes leading to saturation of the electric field, transmitted into the Earth's ionosphere from the solar wind, incorporating features of the coupled system previously ignored. We took into account that the electric field is transmitted into the ionosphere through a region of open field lines, and that the ionospheric conductivity in the polar cap and auroral zone may be different. Penetration of the electric field into the magnetosphere is linked with the generation of the Alfven wave, going out from the ionosphere into the solar wind and being coupled with the field-aligned currents at the boundary of the open field limes. The electric field of the outgoing Alfven wave reduces the original electric field and provides the saturation effect in the electric field and currents during strong geomagnetic disturbances, associated with increasing ionospheric conductivity. The electric field and field-aligned currents of this Alfven wave are dependent on the ionospheric and solar wind parameters and may significantly affect the electric field and field-aligned currents, generated in the polar ionosphere. Estimating the magnitude of the saturation effect in the electric field and field-aligned currents allows us to improve the correlation between solar wind parameters and resulting disturbances in the Earth's magnetosphere.

Magnetic pumping of the solar wind

NASA Astrophysics Data System (ADS)

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.

Ion acceleration by multiple reflections at Martian bow shock

NASA Astrophysics Data System (ADS)

Yamauchi, M.; Futaana, Y.; Fedorov, A.; Frahm, R. A.; Dubinin, E.; Lundin, R.; Sauvaud, J.-A.; Winningham, J. D.; Barabash, S.; Holmström, M.

2012-02-01

The ion mass analyzer (IMA) on board Mars Express revealed bundled structures of ions in the energy domain within a distance of a proton gyroradius from the Martian bow shock. Seven prominent traversals during 2005 were examined when the energy-bunched structure was observed together with pick-up ions of exospheric origin, the latter of which is used to determine the local magnetic field orientation from its circular trajectory in velocity space. These seven traversals include different bow shock configurations: (a) quasi-perpendicular shock with its specular direction of the solar wind more perpendicular to the magnetic field (QT), (b) quasi-perpendicular shock with its specular reflection direction of the solar wind more along the magnetic field (FS), and (c) quasi-parallel (QL) shock. In all seven cases, the velocity components of the energy-bunched structure are consistent with multiple specular reflections of the solar wind at the bow shock up to at least two reflections. The accelerated solar wind ions after two specular reflections have large parallel components with respect to the magnetic field for both QL cases whereas the field-aligned speed is much smaller than the perpendicular speed for all QT cases.

PROTON HEATING BY PICK-UP ION DRIVEN CYCLOTRON WAVES IN THE OUTER HELIOSPHERE: HYBRID EXPANDING BOX SIMULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hellinger, Petr; Trávníček, Pavel M., E-mail: petr.hellinger@asu.cas.cz

Using a one-dimensional hybrid expanding box model, we investigate properties of the solar wind in the outer heliosphere. We assume a proton–electron plasma with a strictly transverse ambient magnetic field and, aside from the expansion, we take into account the influence of a continuous injection of cold pick-up protons through the charge-exchange process between the solar wind protons and hydrogen of interstellar origin. The injected cold pick-up protons form a ring distribution function, which rapidly becomes unstable, and generate Alfvén cyclotron waves. The Alfvén cyclotron waves scatter pick-up protons to a spherical shell distribution function that thickens over that timemore » owing to the expansion-driven cooling. The Alfvén cyclotron waves heat solar wind protons in the perpendicular direction (with respect to the ambient magnetic field) through cyclotron resonance. At later times, the Alfvén cyclotron waves become parametrically unstable and the generated ion-acoustic waves heat protons in the parallel direction through Landau resonance. The resulting heating of the solar wind protons is efficient on the expansion timescale.« less

Particle injection and acceleration at earth's bow shock - Comparison of upstream and downstream events

NASA Technical Reports Server (NTRS)

Ellison, Donald C.; Moebius, Eberhard; Paschmann, Goetz

1990-01-01

The injection and acceleration of thermal solar wind ions at the quasi-parallel earth's bow shock during radial interplanetary magnetic field conditions is investigated. Active Magnetospheric Particle Tracer Explorers/Ion Release Module satellite observations of complete proton spectra, and of heavy ion spectra above 10 keV/Q, made on September 12, 1984 near the nose of the shock, are presented and compared to the predictions of a Monte Carlo shock simulation which includes diffusive shock acceleration. It is found that the spectral observations are in good agreement with the predictions of the simulation when it is assumed that all accelerated ions originate in the solar wind and are injected into the acceleration mechanism by thermal leakage from the downstream plasma. The efficiency, which is determined directly from the downstream observations, is high, with at least 15 percent of the solar wind energy flux going into accelerated particles. The comparisons allow constraints to be placed on the rigidity dependence of the scattering mean free path and suggest that the upstream solar wind must be slowed substantially by backstreaming accelerated ions prior to undergoing a sharp transition in the viscous subshock.

On the physics of waves in the solar atmosphere: Wave heating and wind acceleration

NASA Technical Reports Server (NTRS)

Musielak, Z. E.

1994-01-01

This paper presents work performed on the generation and physics of acoustic waves in the solar atmosphere. The investigators have incorporated spatial and temporal turbulent energy spectra in a newly corrected version of the Lighthill-Stein theory of acoustic wave generation in order to calculate the acoustic wave energy fluxes generated in the solar convective zone. The investigators have also revised and improved the treatment of the generation of magnetic flux tube waves, which can carry energy along the tubes far away from the region of their origin, and have calculated the tube wave energy fluxes for the sun. They also examine the transfer of the wave energy originated in the solar convective zone to the outer atmospheric layers through computation of wave propagation and dissipation in highly nonhomogeneous solar atmosphere. These waves may efficiently heat the solar atmosphere and the heating will be especially significant in the chromospheric network. It is also shown that the role played by Alfven waves in solar wind acceleration and coronal hole heating is dominant. The second part of the project concerned investigation of wave propagation in highly inhomogeneous stellar atmospheres using an approach based on an analytic tool developed by Musielak, Fontenla, and Moore. In addition, a new technique based on Dirac equations has been developed to investigate coupling between different MHD waves propagating in stratified stellar atmospheres.

On the physics of waves in the solar atmosphere: Wave heating and wind acceleration

NASA Technical Reports Server (NTRS)

Musielak, Z. E.

1993-01-01

This paper presents work performed on the generation and physics of acoustic waves in the solar atmosphere. The investigators have incorporated spatial and temporal turbulent energy spectra in a newly corrected version of the Lighthill-Stein theory of acoustic wave generation in order to calculate the acoustic wave energy fluxes generated in the solar convective zone. The investigators have also revised and improved the treatment of the generation of magnetic flux tube waves, which can carry energy along the tubes far away from the region of their origin, and have calculated the tube energy fluxes for the sun. They also examine the transfer of the wave energy originated in the solar convective zone to the outer atmospheric layers through computation of wave propagation and dissipation in highly nonhomogeneous solar atmosphere. These waves may efficiently heat the solar atmosphere and the heating will be especially significant in the chromospheric network. It is also shown that the role played by Alfven waves in solar wind acceleration and coronal hole heating is dominant. The second part of the project concerned investigation of wave propagation in highly inhomogeneous stellar atmospheres using an approach based on an analytic tool developed by Musielak, Fontenla, and Moore. In addition, a new technique based on Dirac equations has been developed to investigate coupling between different MHD waves propagating in stratified stellar atmospheres.

KSC-97DC1286

NASA Image and Video Library

1997-08-19

Final prelaunch preparations are made at Launch Complex 17A, Cape Canaveral Air Station, for liftoff of the Boeing Delta II expendable launch vehicle with the Advanced Composition Explorer (ACE) spacecraft, at top. The black rectangular-shaped panel in front is one of ACE’s solar arrays. ACE will investigate the origin and evolution of solar phenomenon, the formation of solar corona, solar flares and acceleration of the solar wind. This will be the second Delta launch under the Boeing name and the first from Cape Canaveral. Liftoff is scheduled Aug. 24

VARIATIONS IN SOLAR WIND FRACTIONATION AS SEEN BY ACE/SWICS AND THE IMPLICATIONS FOR GENESIS MISSION RESULTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

We use Advanced Composition Explorer (ACE)/Solar Wind Ion Composition Spectrometer (SWICS) elemental composition data to compare the variations in solar wind (SW) fractionation as measured by SWICS during the last solar maximum (1999–2001), the solar minimum (2006–2009), and the period in which the Genesis spacecraft was collecting SW (late 2001—early 2004). We differentiate our analysis in terms of SW regimes (i.e., originating from interstream or coronal hole flows, or coronal mass ejecta). Abundances are normalized to the low-first ionization potential (low-FIP) ion magnesium to uncover correlations that are not apparent when normalizing to high-FIP ions. We find that relative tomore » magnesium, the other low-FIP elements are measurably fractionated, but the degree of fractionation does not vary significantly over the solar cycle. For the high-FIP ions, variation in fractionation over the solar cycle is significant: greatest for Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance ratios are examined as a function of SW speed, we find a strong correlation, with the remarkable observation that the degree of fractionation follows a mass-dependent trend. We discuss the implications for correcting the Genesis sample return results to photospheric abundances.« less

The pick-up of cometary protons by the solar wind

NASA Technical Reports Server (NTRS)

Neugebauer, M.; Goldstein, B. E.; Goldstein, R.; Lazarus, A. J.; Altwegg, K.; Balsiger, H.

1987-01-01

The HERS detector of the Ion Mass Spectrometer on the Giotto spacecraft measured the 3-dimensional distribution of picked-up cometary protons over a distance of about 8 million km upstream of the bow shock of comet P/Hally. The protons were observed to be elastically scattered out of their original cycloidal trajectories such that they were nonuniformly distributed over a spherical shell in velocity space. The shell radius (relative to its expected radius) and thickness increased as the bow shock was approached. Down-stream of the shock, the cometary protons could not be distinguished from the heated solar wind protons.

Evidence for solar wind origin of energetic heavy ions in the earth's radiation belt

NASA Technical Reports Server (NTRS)

Hovestadt, D.; Klecker, B.; Scholer, M.; Gloeckler, G.; Ipavich, F. M.; Fan, C. Y.; Fisk, L. A.; Ogallagher, J. J.

1978-01-01

Analysis of data from our energetic ion composition experiment on ISEE-1 has revealed the presence of substantial fluxes of carbon, oxygen, and heavier ions above 400 keV/nucleon at L values between approximately 2.5 and 4 earth radii. The measured C/O ratio varies systematically from 1.3 at 450 keV/nucleon to 4.1 at 1.3 MeV/nucleon, and no iron is observed above 200 keV/nucleon. These results provide strong evidence for a solar wind origin for energetic ions in the outer radiation belt. The absence of iron and the increase of the carbon-to-oxygen ratio with energy suggest that the condition for the validity of the first adiabatic invariant may have a strong influence on the trapping of these particles.

A model for the origin of high-energy cosmic rays

NASA Technical Reports Server (NTRS)

Jokipii, J. R.; Morfill, G. E.

1985-01-01

It is suggested that cosmic rays, up to the highest energies observed, originate in the Galaxy and are accelerated in astrophysical shock waves. If there is a galactic wind, in analogy with the solar wind, a hierarchy of shocks ranging from supernova shocks to the galactic wind termination shock is expected. This leads to a consistent model in which most cosmic rays, up to perhaps 10 to the 14th eV energy, are accelerated by supernova shocks, but that particles with energies of 10 to the 15th eV and higher are accelerated at the termination shock of the galactic wind. Intermediate energies may be accelerated by intermediate-scale shocks, and there may be larger scale shocks associated with the Local Group of galaxies.

Suprathermal Particle at 1 AU and Their Solar Sources

NASA Astrophysics Data System (ADS)

Ho, G. C.; Ko, Y. K.; Mason, G. M.

2017-12-01

Particles that have energies of a few times the solar wind plasma energy up to 100s of keV/nuc are called suprathermal particles. Both theoretical and observational studies have revealed that these particles play a critical role as seed particles for further acceleration to higher energies. This may occur either close to the Sun in solar energetic particle (SEP) events, but also locally at 1 AU in, e.g., energetic storm particle events. The multiple origins of these suprathermal particles, from SEPs, Corotating Interaction Regions, shocks and other possible sources, have been investigated only roughly in part because the intensities are generally low. One hypothesis is that in some cases a pool of suprathermal particles can form from high-energy SEPs, accelerated during prior and ongoing solar and interplanetary activity, and then losing energy via adiabatic deceleration as they propagate in the expanding solar wind. Another hypothesis is that suprathermal particles are produced along with the thermal solar wind, but from different physical processes. It is therefore important to examine the relationship, if any, between the suprathermal particle properties with those of possible solar source regions. The Ultra-Low Energy Isotope Spectrometer (ULEIS) on ACE makes regular observations of the suprathermal ion composition and spectra at L1. We compare the measured suprathermal particle properties at 1AU and various solar synoptic maps and coronal models to identify any significant relationship between the two.

Nano-Dust Analyzer For the Detection and Chemical Composition Measurement of Particles Originating in the Inner Heliosphere

NASA Astrophysics Data System (ADS)

O'Brien, Leela; Gruen, E.; Sternovsky, Z.; Horanyi, M.; Juhasz, A.; Eberhard, M.; Srama, R.

2013-10-01

The development of the Nano-Dust Analyzer (NDA) instrument and the results from the first laboratory testing and calibration are reported. The two STEREO spacecrafts have indicated that nanometer-sized dust particles, potentially with very high flux, are delivered to 1 AU from the inner solar system [Meyer-Vernet, N. et al., Solar Physics, 256, 463, 2009]. These particles are generated by collisional grinding or evaporation near the Sun and accelerated outward by the solar wind. The temporal variability reveals the complex interaction with the solar wind magnetic field within 1 AU and provides the means to learn about solar wind conditions and can supply additional parameters or verification for heliospheric magnetic field models. The composition analysis will report on the processes that generated the nanometer-sized particle. NDA is a highly sensitive dust analyzer that is developed under NASA's Heliophysics program. The instrument is a linear time-of-flight mass analyzer that utilizes dust impact ionization and is modeled after the Cosmic Dust Analyzer (CDA) on Cassini. By applying technologies implemented in solar wind instruments and coronagraphs, the highly sensitive dust analyzer will be able to be pointed toward the solar direction. A laboratory prototype has been built, tested, and calibrated at the dust accelerator facility at the University of Colorado, Boulder, using particles with 1 to over 50 km/s velocity. NDA is unique in its requirement to operate with the Sun in its field-of-view. A light trap system has been designed and optimized in terms of geometry and surface optical properties to mitigate Solar UV contribution to detector noise. In addition, results from laboratory tests performed with a 1 keV ion beam at the University of New Hampshire’s Space Sciences Facility confirm the effectiveness of the instrument’s solar wind particle rejection system.

A Solar Cycle Dependence of Nonlinearity in Magnetospheric Activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Jay R; Wing, Simon

2005-03-08

The nonlinear dependencies inherent to the historical K(sub)p data stream (1932-2003) are examined using mutual information and cumulant based cost as discriminating statistics. The discriminating statistics are compared with surrogate data streams that are constructed using the corrected amplitude adjustment Fourier transform (CAAFT) method and capture the linear properties of the original K(sub)p data. Differences are regularly seen in the discriminating statistics a few years prior to solar minima, while no differences are apparent at the time of solar maximum. These results suggest that the dynamics of the magnetosphere tend to be more linear at solar maximum than at solarmore » minimum. The strong nonlinear dependencies tend to peak on a timescale around 40-50 hours and are statistically significant up to one week. Because the solar wind driver variables, VB(sub)s and dynamical pressure exhibit a much shorter decorrelation time for nonlinearities, the results seem to indicate that the nonlinearity is related to internal magnetospheric dynamics. Moreover, the timescales for the nonlinearity seem to be on the same order as that for storm/ring current relaxation. We suggest that the strong solar wind driving that occurs around solar maximum dominates the magnetospheric dynamics suppressing the internal magnetospheric nonlinearity. On the other hand, in the descending phase of the solar cycle just prior to solar minimum, when magnetospheric activity is weaker, the dynamics exhibit a significant nonlinear internal magnetospheric response that may be related to increased solar wind speed.« less

Interplanetary Magnetic Field Control of the Entry of Solar Energetic Particles into the Magnetosphere

NASA Technical Reports Server (NTRS)

Richard, R. L.; El-Alaoui, M.; Ashour-Abdalla, M.; Walker, R. J.

2002-01-01

We have investigated the entry of energetic ions of solar origin into the magnetosphere as a function of the interplanetary magnetic field orientation. We have modeled this entry by following high energy particles (protons and 3 He ions) ranging from 0.1 to 50 MeV in electric and magnetic fields from a global magnetohydrodynamic (MHD) model of the magnetosphere and its interaction with the solar wind. For the most part these particles entered the magnetosphere on or near open field lines except for some above 10 MeV that could enter directly by crossing field lines due to their large gyroradii. The MHD simulation was driven by a series of idealized solar wind and interplanetary magnetic field (IMF) conditions. It was found that the flux of particles in the magnetosphere and transport into the inner magnetosphere varied widely according to the IMF orientation for a constant upstream particle source, with the most efficient entry occurring under southward IMF conditions. The flux inside the magnetosphere could approach that in the solar wind implying that SEPs can contribute significantly to the magnetospheric energetic particle population during typical SEP events depending on the state of the magnetosphere.

Tests for coronal electron temperature signatures in suprathermal electron populations at 1 AU

NASA Astrophysics Data System (ADS)

Macneil, Allan R.; Owen, Christopher J.; Wicks, Robert T.

2017-12-01

The development of knowledge of how the coronal origin of the solar wind affects its in situ properties is one of the keys to understanding the relationship between the Sun and the heliosphere. In this paper, we analyse ACE/SWICS and WIND/3DP data spanning > 12 years, and test properties of solar wind suprathermal electron distributions for the presence of signatures of the coronal temperature at their origin which may remain at 1 AU. In particular we re-examine a previous suggestion that these properties correlate with the oxygen charge state ratio O7+ / O6+, an established proxy for coronal electron temperature. We find only a very weak but variable correlation between measures of suprathermal electron energy content and O7+ / O6+. The weak nature of the correlation leads us to conclude, in contrast to earlier results, that an initial relationship with core electron temperature has the possibility to exist in the corona, but that in most cases no strong signatures remain in the suprathermal electron distributions at 1 AU. It cannot yet be confirmed whether this is due to the effects of coronal conditions on the establishment of this relationship or due to the altering of the electron distributions by processing during transport in the solar wind en route to 1 AU. Contrasting results for the halo and strahl population favours the latter interpretation. Confirmation of this will be possible using Solar Orbiter data (cruise and nominal mission phase) to test whether the weakness of the relationship persists over a range of heliocentric distances. If the correlation is found to strengthen when closer to the Sun, then this would indicate an initial relationship which is being degraded, perhaps by wave-particle interactions, en route to the observer.

On Wave Processes in the Solar Atmosphere

NASA Technical Reports Server (NTRS)

Musielak, Z. E.

1998-01-01

This grant was awarded by NASA/MSFC to The University of Alabama in Huntsville (UAH) to investigate the physical processes responsible for heating and wind acceleration in the solar atmosphere, and to construct theoretical, self-consistent and time-dependent solar wind models based on the momentum deposition by finite amplitude and nonlinear Alfven waves. In summary, there are three main goals of the proposed research: (1) Calculate the wave energy spectra and wave energy fluxes carried by magnetic non- magnetic waves. (2) Find out which mechanism dominates in supplying the wave energy to different parts of the solar atmosphere. (3) Use the results obtained in (1) and (2) to construct theoretical, self-consistent and time- dependent models of the solar wind. We have completed the first goal by calculating the amount of non-radiative energy generated in the solar convection zone as acoustic waves and as magnetic tube waves. To calculate the amount of wave energy carried by acoustic waves, we have used the Lighthill-Stein theory for sound generation modified by Musielak, Rosner, Stein & Ulmschneider (1994). The acoustic wave energy fluxes for stars located in different regions of the Hertzsprung-Russell (H-R) diagram have also been computed. The wave energy fluxes carried by longitudinal and transverse waves along magnetic flux tubes have been calculated by using both analytical and numerical methods. Our analytical approach is based a theory developed by Musielak, Rosner & Ulmschnelder and Musielak, Rosner, Gall & Ulmschneider, which allows computing the wave energy fluxes for linear tube waves. A numerical approach has been developed by Huang, Musielak & Ulmschneider and Ulmschneider & Musielak to compute the energy fluxes for nonlinear tube waves. Both methods have been used to calculate the wave energy fluxes for stars located in different regions of the HR diagram (Musielak, Rosner & Ulmschneider 1998; Ulmschneider, Musielak & Fawzy 1998). Having obtained the wave energy fluxes for acoustic and magnetic tube waves, we have investigated the behavior of these waves in the solar and stellar atmospheres. The results of our extensive studies have been published in many papers and presented at numerous scientific meetings. In these studies we have investigated different aspects of propagation of acoustic and magnetic waves, the efficiency of energy transfer along magnetic structures in the solar atmosphere, and behavior of Alfven waves in stgeady and expanding solar and stellar atmospheres. Recently, we have used some of these results to construct first purely theoretical, two component and time-dependent models of solar and stellar chromospheres. Finally, to address the third goal, we have constructed first fully theoretical, self-consistent and time dependent wind models based on the momentum deposition by non-linear Alfven waves. The full set of single-fluid MHD equations with the background flow has been solved by using a modified version of the ZEUS MHD code. The constructed wind models are radially symmetric with the magnetic field decreasing radially and the initial outflow is described by the standard Parker wind solution. In contrast to previous studies, no assumptions regarding wave linearity, wave damping, and wave-flow interaction are made; the models thus naturally account for the backreaction of the wind on the waves as well as for the nonlinear interaction between different types of MHD waves. The models have been used to explain the origin of fast speed streams in solar coronal holes. The obtained results clearly demonstrate that the momentum deposition by Alfven waves in the solar wind can be sufficient to explain the origin of fast stream components of the solar wind. The range of wave amplitudes required to obtain the desired results seems to be in good agreement with recent observations.

The Third Solar Wind Conference: A summary

NASA Technical Reports Server (NTRS)

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.

Orbiting observatory SOHO finds source of high-speed "wind" blowing from the Sun

NASA Astrophysics Data System (ADS)

1999-02-01

"The search for the source of the solar wind has been like the hunt for the source of the Nile," said Dr. Don Hassler of the Southwest Research Institute, Boulder, Colorado, lead author of the paper in Science. "For 30 years, scientists have observed high-speed solar wind coming from regions in the solar atmosphere with open magnetic field lines, called coronal holes. However, only recently, with the observations from SOHO, have we been able to measure the detailed structure of this source region". The solar wind comes in two varieties : high-speed and low-speed. The low-speed solar wind moves at "only" 1.5 million kilometres per hour, while the high-speed wind is even faster, moving at speeds as high as 3 million kilometres per hour. As it flows past Earth, the solar wind changes the shape and structure of the Earth's magnetic field. In the past, the solar wind didn't affect us directly, but as we become increasingly dependent on advanced technology, we become more susceptible to its effects. Researchers are learning that variations in the solar wind flow can cause dramatic changes in the shape of the Earth's magnetic field, which can damage satellites and disrupt communications and electrical power systems. The nature and origin of the solar wind is one of the main mysteries ESA's solar observatory SOHO was designed to solve. It has long been thought that the solar wind flows from coronal holes; what is new is the discovery that these outflows are concentrated in specific patches at the edges of the honeycomb-shaped magnetic fields. Just below the surface of the Sun there are large convection cells, and each cell has a magnetic field associated with it. "If one thinks of these cells as paving stones in a patio, then the solar wind is breaking through like grass around the edges, concentrated in the corners where the paving stones meet", said Dr. Helen Mason, University of Cambridge, England, and co-author of the paper to appear in Science. "However, at speeds ranging from 30,000 km/h at the surface to over 3 million km/h, the solar wind "grows" much faster than grass". "Looking at the spot where the solar wind actually appears is extremely important", says co-author Dr. Philippe Lemaire of the Institut d'Astrophysique Spatiale in Orsay, France. The Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on SOHO detected the solar wind by observing the ultraviolet spectrum over a large area of the solar north polar region. The SUMER instrument was built under the leadership of Dr. Klaus Wilhelm at the Max-Planck-Institut für Aeronomie in Lindau, Germany, with key contributions from the Institut d'Astrophysique Spatiale in Orsay, France, the NASA Goddard Space Flight Center in Greenbelt, Maryland, and the University of California at Berkeley, with financial support from German, French, US and Swiss national agencies. "Identification of the detailed structure of the source region of the fast solar wind is an important step in solving the solar wind acceleration problem. We can now focus our attention on the plasma conditions and the dynamic processes seen in the corners of the magnetic field structures", says Dr. Wilhelm, also co-author of the Science paper. A spectrum results from the separation of light into its component colours, which correspond to different wavelengths. Blue light has a shorter wavelength and is more energetic than red. A spectrum is similar to what is seen when a prism separates white light into a rainbow of distinct colours. By analysing light this way, astronomers learn a great deal about the object emitting the light, such as its temperature, chemical composition, and motion. The ultraviolet light observed by SUMER is actually invisible to the human eye and cannot penetrate the Earth's atmosphere. The hot gas in the solar wind source region emits light at certain ultraviolet wavelengths. When the hot gas flows towards Earth, as it does in the solar wind, the wavelengths of the ultraviolet light emitted become shorter, a phenomenon called Doppler shift. This is similar to the way an ambulance siren appears to change tone as it speeds by. When the ambulance moves towards us, its sound is compressed to a shorter wavelength, resulting in a higher tone. As it moves away, its sound is stretched to a longer wavelength, resulting in a lower tone. Motion towards us, away from the solar surface, was detected as blueshifts and identified as the beginning of the solar wind. SOHO operates at a special vantage point 1.5 million kilometres out in space, on the sunward side of the Earth. The project is an international collaboration between ESA and NASA. SOHO was launched on an Atlas rocket from Cape Canaveral Air Station, Florida, in December 1995 and is operated from the Goddard Space Flight Center in Greenbelt, Maryland.

Forma y acción de la liberación de energía en la atmósfera solar

NASA Astrophysics Data System (ADS)

Mandrini, C. H.

2016-08-01

We briefly describe the lines of work developed over more than twenty years and their relevant results. Our scope is essentially that of active events that occur in the solar atmosphere covering wide temporal and spatial scales and energy range. We present results derived from the comparative analysis of active events and their interplanetary counterparts, as well as of aspects related to the quiet solar atmosphere, such as the heating of the corona and the origin of the slow solar wind.

KSC-97DC1283

NASA Image and Video Library

1997-08-19

Workers make final checks as the second part of the bi-sector payload fairing for the Advanced Composition Explorer (ACE) is closed around the spacecraft at Launch Complex 17A, Cape Canaveral Air Station. ACE will be launched on a Boeing Delta II expendable launch vehicle. The spacecraft will investigate the origin and evolution of solar phenomenon, the formation of solar corona, solar flares and acceleration of the solar wind. This will be the second Delta launch under the Boeing name and the first from Cape Canaveral. Liftoff is scheduled Aug. 24

Turbulent Dissipation and Kinetic Heating in the Solar Wind: Benefits of an Ensemble Simulation Approach

NASA Astrophysics Data System (ADS)

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

2013-12-01

Despite many years of study, the basic physical processes responsible for producing the solar wind are not known -- or at least not universally agreed upon. There are many proposed solutions to the intertwined problems of coronal heating, wind acceleration, and particle energization, and the real problem is how to choose between them. Confirming that any one proposed mechanism is acting in the heliosphere is difficult, not only because measurements are limited, but also because many of the suggested processes act on a huge range of spatial scales (from centimeters to astronomical units) with complex feedback effects that are not yet understood. This presentation will attempt to summarize the outstanding questions in our understanding of the gradual energization of protons, electrons, and heavy ions in the solar wind. The focus will be on the collisionless dissipation of turbulent fluctuations that originate at the solar surface, and how the Turbulent Dissipation Challenge can help identify the dominant physical processes that transfer energy to the particles. We will also discuss the importance of making the best use of in-situ and remote-sensing measurements that probe the highly variable corona and heliosphere. There is key information in the variability that sometimes gets ignored when theorists attempt to model the properties of well-known "mean states" (i.e., fast wind streams from polar coronal holes). Instead, it could be a more convincing test for models to reproduce the full statistical ensemble of plasma/field states observed at a given place in the heliosphere. As an example of this, we will present preliminary results of a Monte Carlo model that aims to reproduce the full distribution of variations in the proton temperature anisotropy and plasma beta measured in the solar wind at 1 AU.

KSC-97PC1236

NASA Image and Video Library

1997-08-12

The Advanced Composition Explorer (ACE) undergoes final prelaunch processing in KSC’s Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2) before being transported to Pad A at Launch Complex 17, Cape Canaveral Air Station, for mating to the Delta II launch vehicle. This photo was taken during a news media opportunity. The worker at right is installing protective covering over one of the spacecraft’s solar arrays. ACE with its combination of nine sensors and instruments will investigate the origin and evolution of solar phenomenon, the formation of solar corona, solar flares and acceleration of the solar wind. Launch is targeted for Aug. 24

Electromagnetic instabilities in solar wind interaction with dusty cometary plasmas

NASA Technical Reports Server (NTRS)

Verheest, Frank; Meuris, Peter

1995-01-01

Dusty plasmas contain charged dust grains which are much more massive than protons, carry high negative charges due to preferential capture of electrons, and do not have a fixed charge. Fluctuations in the grain charges due to liberation or capture of additional electrons and protons translate as mass and momentum losses or gains for these species, which can render linear modes unstable. On the other hand, many authors have addressed the pickup of ions of cometary origin by the solar wind, which for the parallel part is due to relative streaming between cometary and solar wind ions which excites low-frequency electromagnetic turbulence. In the present work we look again at those instabilities by including effects due to the presence of charged dust in the cometary environments. We have investigated several frequency regimes: nonresonant below the cometary watergroup gyrofrequency, nonresonant below the cometary charged dust gyrofrequency (new and interesting but highly unlikely!) and resonant with the cometary watergroup ions. For most parameter ranges either the existing instabilities are enhanced, showing that the presence of charged dust facilitates the cometary ion pickup by the solar wind, or new instabilities have been shown to exist. Similar conclusions might be relevant for other kinds of astrophysical and heliospheric plasmas containing charged dust, as in planetary rings.

Is tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control?

NASA Astrophysics Data System (ADS)

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 (Prikryl et al., Ann. Geophys., 27, 31-57, 2009). 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.

Evidence of active region imprints on the solar wind structure

NASA Technical Reports Server (NTRS)

Hick, P.; Jackson, B. V.

1995-01-01

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

A theory of local and global processes which affect solar wind electrons. 1: The origin of typical 1 AU velocity distribution functions: Steady state theory

NASA Technical Reports Server (NTRS)

Scudder, J. D.

1978-01-01

A detailed first principle kinetic theory for electrons which is neither a classical fluid treatment nor an exospheric calculation is presented. This theory illustrates the global and local properties of the solar wind expansion that shape the observed features of the electron distribution function, such as its bifurcation, its skewness and the differential temperatures of the thermal and suprathermal subpopulations. Coulomb collisions are substantial mediators of the interplanetary electron velocity distribution function and they place a zone for a bifurcation of the electron distribution function deep in the corona. The local cause and effect precept which permeates the physics of denser media is modified for electrons in the solar wind. The local form of transport laws and equations of state which apply to collision dominated plasmas are replaced with global relations that explicitly depend on the relative position of the observer to the boundaries of the system.

Solar, planetary, and other inert gases in two sieve fractions of a disaggregated Allende sample - A study by stepwise heating extraction

NASA Technical Reports Server (NTRS)

Palma, R. L.; Heymann, D.

1988-01-01

Inert gases released by stepwise heating of unaltered, strongly magnetic, and weakly magnetic samples from the 0-64 micron and the 105-250 micron fractions of a disaggregated and sieved sample of the Allende meteorite reveal the occurrence of both solar and planetary neon. The origin of the solar neon is thought to be implantation of solar wind ions. The origin of the planetary neon remains unresolved. Heavy isotope enriched components of krypton and xenon have been detected and there are some indications that a light krypton component may also be present. Other than a larger concentration of Xe-129 in the weakly magnetic samples, the signatures of the magnetic separates are isotopically very similar.

Nonlinear Evolution of Observed Fast Streams in the Solar Wind - Micro-instabilities and Energy Exchange between Protons and Alpha Particles

NASA Astrophysics Data System (ADS)

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.

The Statistical Mechanics of Solar Wind Hydroxylation at the Moon, Within Lunar Magnetic Anomalies, and at Phobos

NASA Technical Reports Server (NTRS)

Farrell, W. M.; Hurley, D. M.; Esposito, V. J.; Mclain, J. L.; Zimmerman, M. I.

2017-01-01

We present a new formalism to describe the outgassing of hydrogen initially implanted by the solar wind protons into exposed soils on airless bodies. The formalism applies a statistical mechanics approach similar to that applied recently to molecular adsorption onto activated surfaces. The key element enabling this formalism is the recognition that the interatomic potential between the implanted H and regolith-residing oxides is not of singular value but possess a distribution of trapped energy values at a given temperature, F(U,T). All subsequent derivations of the outward diffusion and H retention rely on the specific properties of this distribution. We find that solar wind hydrogen can be retained if there are sites in the implantation layer with activation energy values exceeding 0.5eV. We especially examine the dependence of H retention applying characteristic energy values found previously for irradiated silica and mature lunar samples. We also apply the formalism to two cases that differ from the typical solar wind implantation at the Moon. First, we test for a case of implantation in magnetic anomaly regions where significantly lower-energy ions of solar wind origin are expected to be incident with the surface. In magnetic anomalies, H retention is found to be reduced due to the reduced ion flux and shallower depth of implantation. Second, we also apply the model to Phobos where the surface temperature range is not as extreme as the Moon. We find the H atom retention in this second case is higher than the lunar case due to the reduced thermal extremes (that reduces outgassing).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tracy, Patrick J.; Kasper, Justin C.; Zurbuchen, Thomas H.

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{sup +}) and alpha particles (He{sup 2+}). From these rates, wemore » 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 He{sup 2+} and C{sup 6+} follow a monotonic decay toward equal temperatures with protons with increasing collisional age, but O{sup 6+} shows a noted deviation from this monotonic decay. Furthermore, we show that the deviation from monotonic decay for O{sup 6+} 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.« less

Soho and Cluster - The scientific instruments

NASA Technical Reports Server (NTRS)

Domingo, V.; Schmidt, R.; Poland, A. I.; Goldstein, M. L.

1988-01-01

The mission goals and instrumentation of the Soho and cluster spacecraft to be launched in 1995 as part of the international Solar-Terrestrial Science Program are discussed. Instruments such as normal-incidence, grazing-incidence, and EUV coronal spectrometers aboard the Soho spacecraft will study the origin of the solar wind and the physical properties of the solar atmosphere. The four Cluster spacecraft will measure electric and magnetic fields, plasmas, and energetic particles using instruments including a wide-band receiver system, a relaxation sounder, and a search coil magnetometer.

Earth Science

NASA Image and Video Library

1995-12-02

The Solar Heliospheric Observatory (SOHO) is launched atop an ATLAS-IIAS expendable launch vehicle. Liftoff from launch complex 36B at Cape Canaveral Air Station marked the 10th Atlas launch from the Eastern range for 1995. SOHO is a cooperative effort involving NASA and the European Space Agency (ESA) within the framework of the International Solar-Terrestrial Physics Program. During its 2-year mission, the SOHO spacecraft gathered data on the internal structure of the Sun, its extensive outer atmosphere and the origin of the solar wind.

Elemental composition of solar energetic particles

NASA Technical Reports Server (NTRS)

Cook, W. R.; Stone, E. C.; Vogt, R. E.

1984-01-01

The Low Energy Telescopes on the Voyager spacecraft have been used to measure the elemental composition (Z = 2-28) and energy spectra (5-15 MeV per nucleon) of solar energetic particles (SEPs) in seven large flare events. Four flare events were selected which have SEP abundance ratios approximately independent of energy per nucleon. For these selected flare events, SEP composition results may be described by an average composition plus a systematic flare-to-flare deviation about the average. The four-flare average SEP composition is systematically different from the solar composition determined by photospheric spectroscopy. These systematic composition differences are apparently not due to SEP propagation or acceleration effects. In contrast, the four-flare average SEP composition is in agreement with measured solar wind abundances and with a number of recent spectroscopic coronal abundance measurements. These findings suggest that SEPs originate in the corona, and that both SEPs and the solar wind sample a coronal composition which is significantly and persistently different from that measured for the photosphere.

Coronal mass ejections and their sheath regions in interplanetary space

NASA Astrophysics Data System (ADS)

Kilpua, Emilia; Koskinen, Hannu E. J.; Pulkkinen, Tuija I.

2017-11-01

Interplanetary coronal mass ejections (ICMEs) are large-scale heliospheric transients that originate from the Sun. When an ICME is sufficiently faster than the preceding solar wind, a shock wave develops ahead of the ICME. The turbulent region between the shock and the ICME is called the sheath region. ICMEs and their sheaths and shocks are all interesting structures from the fundamental plasma physics viewpoint. They are also key drivers of space weather disturbances in the heliosphere and planetary environments. ICME-driven shock waves can accelerate charged particles to high energies. Sheaths and ICMEs drive practically all intense geospace storms at the Earth, and they can also affect dramatically the planetary radiation environments and atmospheres. This review focuses on the current understanding of observational signatures and properties of ICMEs and the associated sheath regions based on five decades of studies. In addition, we discuss modelling of ICMEs and many fundamental outstanding questions on their origin, evolution and effects, largely due to the limitations of single spacecraft observations of these macro-scale structures. We also present current understanding of space weather consequences of these large-scale solar wind structures, including effects at the other Solar System planets and exoplanets. We specially emphasize the different origin, properties and consequences of the sheaths and ICMEs.

Interaction of the Local Interstellar Medium with the Heliosphere: Role of the Interior and Exterior Magnetic Fields

NASA Technical Reports Server (NTRS)

Barnes, Aaron; DeVincenzi, Donald (Technical Monitor)

2000-01-01

A complete model of the global interaction between the solar wind and the local interstellar medium must take account of interstellar neutral atoms, interstellar ionized gas, solar and galactic magnetic fields, galactic and anomalous cosmic rays. For now, however, in view of the many uncertainties about conditions in the interstellar medium, etc., all models must be regarded as highly idealized and incomplete. In the present review I concentrate on the role of magnetic fields of solar and interstellar origin. The former, the interior field, has negligible influence on the unshocked solar wind; the immediate post-shock solar wind is probably low-beta, so that the interior magnetic field is still unimportant, but this situation changes as the plasma flows through the heliosheath, and a ridge of strong magnetic field may form to separate materials of polar and equatorial origin. The exterior (interstellar) field is likely to play an important role in determining the global morphology of the system outside the termination shock. If the exterior field is strong enough, it can compress the heliosphere (although exterior neutral and/or ionized hydrogen may play the dominant role). Even if the interstellar magnetic field does not provide the dominant pressure, its orientation can substantially affect the configuration of the heliosphere, especially the location and orientation of the heliospheric discontinuities. The configurations can be quite different for the situations in which the field and flow are (a) aligned or (b) transverse. Obliquity of the field produces asymmetry in the geometry of the system; in particular the noses of heliopause and interstellar bow shock are shifted away from the interstellar flow direction, and in opposite directions, due to the asymmetric draping of the magnetic field.

Amplitudes of solar modulation of low energy cosmic rays

NASA Technical Reports Server (NTRS)

Von Rosenvinge, T. T.; Paizis, C.

1982-01-01

There have been differences of opinion regarding the origin and behavior of the solar modulation of galactic cosmic rays. It has been shown that the return to solar maximum intensity levels beginning in early 1978 was dominated by Forbush decreases. These Forbush decreases were caused by radially moving interplanetary shocks resulting from large solar flares. The present investigation is concerned with solar modulation effects which were observed during the previous solar minimum. The effects were associated with high-speed streams in the solar wind. These streams caused the formation of corotating interaction regions with both forward and reverse shocks. The modulation effects seen near earth are intimately connected with these shocks.

Space climate implications from substorm frequency

NASA Astrophysics Data System (ADS)

Newell, P. T.; Gjerloev, J. W.; Mitchell, E. J.

2013-10-01

solar wind impacting the Earth varies over a wide range of time scales, driving a corresponding range of geomagnetic activity. Past work has strongly indicated that the rate of merging on the frontside magnetosphere is the most important predictor for magnetospheric activity, especially over a few hours. However, the magnetosphere exhibits variations on other time scales, including UT, seasonal, and solar cycle variations. Much of this geomagnetic variation cannot be reasonably attributed to changes in the solar wind driving—that is, it is not created by the original Russell-McPherron effect or any generalization thereof. In this paper we examine the solar cycle, seasonal, and diurnal effects based upon the frequency of substorm onsets, using a data set of 53,000 substorm onsets. These were identified through the SuperMAG collaboration and span three decades with continuous coverage. Solar cycle variations include a profound minimum in 2009 (448 substorms) and peak in 2003 (3727). The magnitude of this variation (a factor of 8.3) is not explained through variations in estimators of the frontside merging rate (such as dΦMP/dt), even when the more detailed probability distribution functions are examined. Instead, v, or better, n1/2v2 seems to be implicated in the dramatic difference between active and quiet years, even beyond the role of velocity in modulating merging. Moreover, we find that although most substorms are preceded by flux loading (78.5% are above the mean and 83.8% above median solar wind driving), a high solar wind v is almost as important (68.3% above mean, 74.8% above median). This and other evidence suggest that either v or n1/2v2 (but probably not p) plays a strong secondary role in substorm onset. As for the seasonal and diurnal effects, the elliptical nature of the Earth's orbit, which is closest to the Sun in January, leads to a larger solar wind driving (measured by Bs, vBs, or dΦMP/dt) in November, as is confirmed by 22 years of solar wind observations. However, substorms peak in October and March and have a UT dependence best explained by whether a conducting path established by solar illumination exists in at least one hemisphere in the region where substorm onsets typically occur.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-10

... 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...

Distribution Strategies for Solar and Wind Renewables in NW Europe

NASA Astrophysics Data System (ADS)

Smedley, Andrew; Webb, Ann

2017-04-01

Whilst the UNFCCC Paris Agreement Climate change was ratified in November, 2016 saw the highest global temperature anomaly on record at 1.2°C above pre-industrial levels. As such there is urgent need to reduce CO2 emissions by a move away from fossil fuels and towards renewable electricity energy technologies. As the principal renewable technologies of solar PV and wind turbines contribute an increasing fraction to the electricity grid, questions of cumulative intermittency and the large-scale geographic distribution of each technology need to be addressed. In this study our initial emphasis is on a calculation of a relatively high spatial resolution (0.1° × 0.1°) daily gridded dataset of solar irradiance data, over a 10 year period (2006-2015). This is achieved by coupling established sources of satellite data (MODIS SSF level2 instantaneous footprint data) to a well-validated radiative transfer model, here LibRadTran. We utilise both a morning and afternoon field for two cloud layers (optical depth and cloud fraction) interpolated to hourly grids, together with aerosol optical depth, topographic height and solar zenith angle. These input parameters are passed to a 5-D LUT of LibRadTran results to construct hourly estimates of the solar irradiance field, which is then integrated to a daily total. For the daily wind resource we rely on the 6 hourly height-adjusted ECMWF ERA-Interim reanalysis wind fields, but separated into onshore, offshore and deep water components. From these datasets of the solar and wind resources we construct 22 different distribution strategies for solar PV and wind turbines based on the long-term availability of each resource. Combining these distributions with the original daily gridded datasets enables each distribution strategy to be then assessed in terms of the day-to-day variability, the installed capacity required to maintain a baseline supply, and the relative proportions of each technology. Notably for the NW European area considered we find that distribution strategies that only deploy renewables in regions with the highest annual mean irradiance or wind resource, also minimise the total required installed capacity and typically exhibit the smallest output range. Further in the majority of strategies we find that the onshore and offshore wind resource fractions fall to zero with the wind contribution being fully composed of deep water installations. Only as the strategy is to increasingly concentrate each technology in areas with the highest annual mean resource do firstly offshore, and then onshore wind, contribute.

NANODUST DETECTION BETWEEN 1 AND 5 AU USING CASSINI WAVE MEASUREMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schippers, P.; Vernet, N. Meyer-; Lecacheux, A.

The solar system contains solids of all sizes, ranging from kilometer-sized bodies to nano-sized particles. Nanograins have been detected in situ in the Earth's atmosphere, near cometary and giant planet environments, and more recently in the solar wind at 1 AU. The latter nanograins are thought to be formed in the inner solar system dust cloud, mainly through the collisional break-up of larger grains, and are then picked up and accelerated by the magnetized solar wind because of their large charge-to-mass ratio. In the present paper, we analyze the low frequency bursty noise identified in the Cassini radio and plasma wavemore » data during the spacecraft cruise phase inside Jupiter's orbit. The magnitude, spectral shape, and waveform of this broadband noise are consistent with the signatures of the nano particles that traveled at solar wind speed and impinged on the spacecraft surface. Nanoparticles were observed whenever the radio instrument was turned on and able to detect them at different heliocentric distances between Earth and Jupiter, suggesting their ubiquitous presence in the heliosphere. We analyzed the radial dependence of the nanodust flux with heliospheric distance and found that it is consistent with the dynamics of nanodust originating from the inner heliosphere and picked up by the solar wind. The contribution of the nanodust produced in the asteroid belt appears to be negligible compared to the trapping region in the inner heliosphere. In contrast, further out, nanodust is mainly produced by the volcanism of active moons such as Io and Enceladus.« less

Origin, transport, and losses of energetic He(+) and He(2+) ions in the magnetosphere of the Earth - AMPTE/CCE observations

NASA Technical Reports Server (NTRS)

Kremser, G.; Wilken, B.; Gloeckler, G.; Hamilton, D. C.; Ipavich, F. M.; Kistler, L. M.; Tanskanen, P.

1993-01-01

Data from the ion charge-energy-mass spectrometer CHEM flown on AMPTE/CCE spacecraft are used to investigate the origin, transport, and losses of energetic He(+) and He(2+) ions in the earth's magnetosphere. The L profiles of the average ion phase space density f were determined as a function of the magnetic momentum. It is shown that the L profiles have an inner part, where f increases with L for both He(+) adn He(2+) and where steady-state conditions are fulfilled. The outer boundary L(lim) of this region is located at a distance that depends on the ion species and the geomagnetic activity level. Steady-state conditions continue outside L(lim) for He(+) ions, while the He(2+) ion distribution outside L(lim) is strongly influenced by ion convection causing a lack of steady-state conditions. It is concluded that solar wind is the origin of the He(2+), while a mixed origin is suggested for the He(+) ions, in which the major contribution is from the solar wind via charge exchange production from the He(2+) ions.

Interplanetary Type III Bursts and Electron Density Fluctuations in the Solar Wind

NASA Astrophysics Data System (ADS)

Krupar, V.; Maksimovic, M.; Kontar, E. P.; Zaslavsky, A.; Santolik, O.; Soucek, J.; Kruparova, O.; Eastwood, J. P.; Szabo, A.

2018-04-01

Type III bursts are generated by fast electron beams originated from magnetic reconnection sites of solar flares. As propagation of radio waves in the interplanetary medium is strongly affected by random electron density fluctuations, type III bursts provide us with a unique diagnostic tool for solar wind remote plasma measurements. Here, we performed a statistical survey of 152 simple and isolated type III bursts observed by the twin-spacecraft Solar TErrestrial RElations Observatory mission. We investigated their time–frequency profiles in order to retrieve decay times as a function of frequency. Next, we performed Monte Carlo simulations to study the role of scattering due to random electron density fluctuations on time–frequency profiles of radio emissions generated in the interplanetary medium. For simplification, we assumed the presence of isotropic electron density fluctuations described by a power law with the Kolmogorov spectral index. Decay times obtained from observations and simulations were compared. We found that the characteristic exponential decay profile of type III bursts can be explained by the scattering of the fundamental component between the source and the observer despite restrictive assumptions included in the Monte Carlo simulation algorithm. Our results suggest that relative electron density fluctuations < δ {n}{{e}}> /{n}{{e}} in the solar wind are 0.06–0.07 over wide range of heliospheric distances.

Modeling and Observation of Interstellar He+ Pickup Ions in the Inner Heliosphere

NASA Astrophysics Data System (ADS)

Chen, Junhong

Interstellar pickup ions constitute a charged particle population that originates from interstellar neutrals inside the heliosphere. They are produced by photoionization, charge exchange with solar wind ions, and electron impact ionization (EI). Once ionized, they are picked up by the interplanetary magnetic field (IMF) and rapidly swept outward with the solar wind. Typically, pickup ion distributions have been described in terms of a velocity distribution function that evolves through fast pitch angle scattering followed by adiabatic cooling during radial transport in the reference frame of the solar wind [e.g., Vasyliunas & Siscoe, 1976, VS76 hereafter]. In the VS76 model, the slope of the isotropic velocity distributions is controlled by the combination of the ionization rate and the cooling process. Thus far, for the cooling index that relates the slope of the velocity distribution to the radial transport and expansion of the pickup ions a constant value of 3/2 has been widely used. The implicit assumptions to arrive at this value are immediate PUI isotropization due to pitch angle scattering and solar wind expansion with the square of the distance from the Sun. Any experimental determination of the cooling index depends on the knowledge of the ionization rate and its spatial variation, as well as solar wind and interplanetary conditions. In this thesis, we study their influences on the PUI cooling index and separate them by making use of the two complementary helium PUI data sets from SWICS instrument on the ACE spacecraft, and PLASTIC instrument on STEREO spacecraft. We use the pickup ion observations from ACE SIWCS in the last solar cycle to determine the cooling index, and the possible effects of the electron impact ionization on the determination of the cooling index. With pickup ion observations from STEREO PLASTIC, we determine how solar wind expansion patterns affect the cooling index. We find that the cooling index varies substantially with solar activity and suspect that these variations may be due to the influence of electron impact ionization, solar wind structures, and slow pitch angle scattering. Electron impact ionization, which does not scale as 1/r 2, is shown to have negligible influence on the cooling index and its variations. However, the effects of solar wind compression and rarefaction regions are found to be important. Comparisons of the pickup ion cooling behavior in the compression and rarefaction regions show that the radial solar wind expansion behaviors that differer from the usual 1/r 2 scaling may play the leading roles in the observed variations. A kinetic model of PUI is used to quantitatively describe their behavior in co-rotating interaction regions (CIR). The simulated distributions mimic closely the observed variations in the cooling behavior of PUIs in these regions. In addition, suprathermal tails appear to emerge from the PUI distributions inside compression regions, which provide further evidence that some particles of this population are accelerated locally in CIR compression regions even in the absence of shocks.

Local and nonlocal geometry of interplanetary coronal mass ejections: Galactic cosmic ray (GCR) short-period variations and magnetic field modeling

NASA Astrophysics Data System (ADS)

Quenby, J. J.; Mulligan, T.; Blake, J. B.; Mazur, J. E.; Shaul, D.

2008-10-01

Energetic galactic cosmic ray (GCR) particles, arriving within the solar system, are modulated by the overall interplanetary field carried in the solar wind. Localized disturbances related to solar activity cause further reduction in intensity, the largest being Forbush decreases in which fluxes can fall ˜20% over a few days. Understanding Forbush decreases leads to a better understanding of the magnetic field structure related to shock waves and fast streams originating at the Sun since the propagation characteristics of the GCR probe much larger regions of space than do individual spacecraft instruments. We examined the temporal history of the integral GCR fluence (≥100 MeV) measured by the high-sensitivity telescope (HIST) aboard the Polar spacecraft, along with the solar wind magnetic field and plasma data from the ACE spacecraft during a 40-day period encompassing the 25 September 1998 Forbush decrease. We also examined the Forbush and (energetic storm particles) ESP event on 28 October 2003. It is the use of HIST in a high-counting-rate integral mode that allows previously poorly seen, short-scale depressions in the GCR fluxes to be observed, adding crucial information on the origin of GCR modulation. Variability on time scales within the frequency range 0.001-1.0 mHz is detected. This paper concentrates on investigating four simple models for explaining short-term reductions in the GCR intensity of both small and large amplitude. Specifically, these models are a local increase in magnetic scattering power, the passage of a shock discontinuity, and the passage of a tangential discontinuity or magnetic rope in the solar wind plasma. Analysis of the short-scale GCR depressions during a test period in September through October 1998 shows that they are not correlated with changes in magnetic scattering power or fluctuations in solar wind speed or plasma density. However, magnetic field and plasma data during the test period of Forbush decrease strongly suggest the presence of an interplanetary coronal mass ejection (ICME). Use of a non-force-free magnetic rope model in conjunction with the energetic particle data allows modeling of the geometry of the ICME in terms of a magnetic cloud topology. It is only this cloud configuration that allows a satisfactory explanation of the magnitude of the Forbush event of 25 September 1998. Calculations made during the test period point to short-scale GCR depressions being caused by either small-scale magnetic flux rope structures or possibly tangential discontinuities in the solar wind.

Inert gases in Sea of Fertility regolith

NASA Technical Reports Server (NTRS)

Vinogradov, A. P.; Zadorozhnyy, I. K.

1974-01-01

The content and isotopic composition were studied of inert gases -- He, Ne, Ar, Kr, and Xe -- in samples of lunar regolith returned by the Luna 16 automatic station. The samples were taken from depths of about 12 and 30 cm. The high concentrations of inert gases exceed by several orders their concentrations observed in ordinary stony meteorites. The gases in lunar regolith were a complex mixture of gases of different origins: Solar, cosmogenic, radiogenic, and so on. Solar wind gases predominated, distributed in the thin surficial layer of the regolith grains. The concentrations of these gases in the surficial layer is several cubic centimeters per gram. The isotopic composition of the inert gases of solar origin approaches their composition measured in gas-rich meteorites.

Relation of large-scale coronal X-ray structure and cosmic rays. I - Sources of solar wind streams as defined by X-ray emission and H-alpha absorption features

NASA Technical Reports Server (NTRS)

Krieger, A. S.; Nolte, J. T.; Sullivan, J. D.; Lazarus, A. J.; Mcintosh, P. S.; Gold, R. E.; Roelof, E. C.

1975-01-01

The large-scale structure of the corona and the interplanetary medium during Carrington rotations 1601-1607 is discussed relative to recurrent high-speed solar wind streams and their coronal sources. Only streams A, C, D, and F recur on more than one rotation. Streams A and D are associated with coronal holes, while C and F originate in the high corona (20-50 solar radii) over faint X-ray emissions. The association of the streams with holes is confirmed by earlier findings that there are no large equatorial holes without an associated high-speed stream and that the area of the equatorial region of coronal holes is highly correlated with the maximum velocity observed in the associated stream near 1 AU.

Solar forcing, and ionospheric ion outflow from Venus, Earth and Mars - A comparison

NASA Astrophysics Data System (ADS)

Lundin, R. N.

2012-12-01

Solar forcing by e.g. EUV radiation and the solar wind leads to outflow and escape of ionospheric ions from Earth, Venus and Mars. In-situ measurements in the Earth's space environment have demonstrated that the ion escape rate correlates with the magnitude of solar forcing, i.e. high solar EUV and solar wind forcing leads to enhanced escape rates. The Terrestrial outflow is dominated by H+ and O+ suggesting that the ultimate origin of outflowing ions is water. Recent measurements from the two arid planets Mars and Venus, their atmospheres dominated by CO2, display characteristics similar to that of the Earth - an outflow dominated by hydrogen (H+) and oxygen (O+, O2+) ions. Despite major differences in atmospheric composition, the composition of the ion outflow from Earth and Venus is very similar, i.e. H+ and O+ dominates and the outflow has a stoichiometric H/O ratio of close to 2. The latter implies escape of water. The ion outflow from Mars is dominated by O+, O2+, and H+. Here the stoichiometric ratio between hydrogen and oxygen ion is ≈1, implying that if the ion outflow originates from water, about half of the hydrogen mass disappears by other means. The primary origin of the ion outflow from Earth, Venus and Mars is a complex issue. Nevertheless, a predominant hydrogen and oxygen loss implies that water can easily escape planets orbiting close to the Sun, while Carbon-based molecules (e.g. CO2) resides more easily. Observations shows that the outflow of e.g. CO+ and CO2+ from Mars and Venus is minute compared to the outflow of hydrogen and oxygen ions. Magnetic shielding is an issue affecting the net ion outflow and escape from a planet, because acceleration processes are also the characteristics of magnetized plasmas. Recent findings suggests that, despite magnetic field pile-up at Mars and Venus, the stand-off distance is insufficient to prohibit a direct interaction between the solar wind and the magnetized ionospheric plasma in the induced magnetospheres of Mars and Venus. On the other hand, a planetary magnetic field, such as the Earth's dipole field and the Martian multipole crustal field, may foster shielding as well as plasma acceleration. However, in this case the ion acceleration may be confined in closed planetary magnetic flux tubes, leading to a low escape rates.

MESSENGER: Exploring Mercury's Magnetosphere

NASA Technical Reports Server (NTRS)

Slavin, James A.; Krimigis, Stamatios M.; Acuna, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Levi, Stefano; Mauk, Barry H.; Solomon, Sean C.;

Coordinated science with the Solar Orbiter, Solar Probe Plus, Interhelioprobe and SPORT missions

NASA Astrophysics Data System (ADS)

Maksimovic, Milan; Vourlidas, Angelos; Zimovets, Ivan; Velli, Marco; Zhukov, Andrei; Kuznetsov, Vladimir; Liu, Ying; Bale, Stuart; Ming, Xiong

The concurrent science operations of the ESA Solar Orbiter (SO), NASA Solar Probe Plus (SPP), Russian Interhelioprobe (IHP) and Chinese SPORT missions will offer a truly unique epoch in heliospheric science. While each mission will achieve its own important science objectives, taken together the four missions will be capable of doing the multi-point measurements required to address many problems in Heliophysics such as the coronal origin of the solar wind plasma and magnetic field or the way the Solar transients drive the heliospheric variability. In this presentation, we discuss the capabilities of the four missions and the Science synergy that will be realized by concurrent operations

Magnetic field observations near Mercury: Preliminary results from Mariner 10

NASA Technical Reports Server (NTRS)

Ness, N. F.; Behannon, K. W.; Lepping, R. P.; Whang, Y. C.; Schatten, K. H.

1974-01-01

Results are presented from a preliminary analysis of data obtained near Mercury by the NASA/GSFC Magnetic Field Experiment on Mariner 10. A very well developed, detached bow shock wave, which developed as the super-Alfvenic solar wind interacted with the planet Mercury was observed. A magnetosphere-like region, with maximum field strength of 98 gamma at closest approach (704 km altitude) was also observed, and was contained within boundaries similar to the terrestrial magnetopause. The obstacle deflecting the solar wind flow was global in size, but the origin of the enhanced magnetic field was not established. The most plausible explanation, considering the complete body of data, favored the conclusion that Mercury has an intrinsic magnetic field.

Connection of the solar wind with the interstellar medium through numerical modeling

DOE PAGES

Heerikhuisen, J.; Zirnstein, E.; Kawamura, A. D.; ...

2013-06-13

In this article we investigate the interaction between the solar wind (SW) and the local interstellar medium (LISM) using spacecraft data and numerical simulations. In particular, we focus on neutral atom results from NASA's Interstellar Boundary EXplorer (IBEX) mission, and compare these with implementations of our neutral atom models that look at both the energetic neutral atoms (ENAs) which are created as hydrogen of LISM origin interacts with the heliosphere, as well as the transmission of interstellar Oxygen through the heliospheric interface. Lastly, the goal of this work is to better understand the global structure of the heliosphere and itsmore » interaction with the galaxy.« less

Solar wind and extreme ultraviolet modulation of the lunar ionosphere/exosphere

NASA Technical Reports Server (NTRS)

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.

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

NASA Technical Reports Server (NTRS)

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.

Measurements of H(+), He(2+), and He(+), in Corotating Interaction Regions at 1 AU

NASA Astrophysics Data System (ADS)

Chotoo, Kancham

Using the Supra-Thermal Ion Composition Spectrometer (STICS) from the SMS experiment on the WIND spacecraft, measurements of H+, He2+, and He+ were made during two corotating interacting regions (CIRs) at 1 AU. The unique energy range of STICS (6-198 keV/e) allowed simultaneous observation of the pre- and post-accelerated ions. These observations gave important clues about the source population, injection, acceleration mechanism, and ion transport in CIRs. The abundance of He2+ relative to H+ in the velocity range 2.5-6.0 times the solar wind velocity, VSW, (5-90 keV/amu) was between 0.11-0.18, which is more than double the solar wind values. However, the same ratio was observed in the suprathermal tail above 1.4 VSW in the spacecraft frame or above ~0.4 VSW in the solar wind frame. This suggests that the H+ and He2+ ions are injected equally into the CIR acceleration process from the suprathermal tail of the solar wind. At 1 AU the H+ and He2+ ions are primarily from the solar wind, but the He+ ions are interstellar pickup ions. The He+/He2+ ratio at 1 AU was ~0.15 for the same velocity range as above. However, this ratio was greater than 1.0 at 4.5 AU as measured previously (Gloeckler et al., 1994). This shows that the relative contribution of the pickup He+ ions to the seed population increases with radial distance away from the Sun. By combining data from three separate sensors on WIND (SMS-MASS, SMS-STICS, and EPACT-STEP), the extended helium distribution was presented for solar wind ions (~1 keV/amu) through energetic particles up to ~1 MeV/amu. The distribution covered 14 orders of magnitude in phase space density. This is the first time such an extended helium distribution is being reported at any radial distance. Using the Fisk and Lee (1980) model to fit the data between ~10-1000 keV/amu, the energetic particles were found to originate from 1.0-1.2 AU and not from beyond 2 AU, as is conventional believed. Anisotropy measurements were made using STICS for both the H+ and He2+ ions in the solar wind frame, and the results were compared to those made by EPACT-STEP. For both time intervals, the anisotropy directions showed significant deviations away from the average magnetic field direction in agreement with the STEP observations of Dwyer et al. (1997).

A study of the solar wind deceleration in the Earth's foreshock region

NASA Technical Reports Server (NTRS)

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.

Origin and Ion Charge State Evolution of Solar Wind Transients during 4 - 7 August 2011

NASA Astrophysics Data System (ADS)

Rodkin, D.; Goryaev, F.; Pagano, P.; Gibb, G.; Slemzin, V.; Shugay, Y.; Veselovsky, I.; Mackay, D. H.

2017-07-01

We present a study of the complex event consisting of several solar wind transients detected by the Advanced Composition Explorer (ACE) on 4 - 7 August 2011, which caused a geomagnetic storm with Dst=-110 nT. The supposed coronal sources, three flares and coronal mass ejections (CMEs), occurred on 2 - 4 August 2011 in active region (AR) 11261. To investigate the solar origin and formation of these transients, we study the kinematic and thermodynamic properties of the expanding coronal structures using the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) EUV images and differential emission measure (DEM) diagnostics. The Helioseismic and Magnetic Imager (HMI) magnetic field maps were used as the input data for the 3D magnetohydrodynamic (MHD) model to describe the flux rope ejection (Pagano, Mackay, and Poedts, 2013b). We characterize the early phase of the flux rope ejection in the corona, where the usual three-component CME structure formed. The flux rope was ejected with a speed of about 200 km s^{-1} to the height of 0.25 R_{⊙}. The kinematics of the modeled CME front agrees well with the Solar Terrestrial Relations Observatory (STEREO) EUV measurements. Using the results of the plasma diagnostics and MHD modeling, we calculate the ion charge ratios of carbon and oxygen as well as the mean charge state of iron ions of the 2 August 2011 CME, taking into account the processes of heating, cooling, expansion, ionization, and recombination of the moving plasma in the corona up to the frozen-in region. We estimate a probable heating rate of the CME plasma in the low corona by matching the calculated ion composition parameters of the CME with those measured in situ for the solar wind transients. We also consider the similarities and discrepancies between the results of the MHD simulation and the observations.

A study of 36Cl production in the early Solar System

NASA Astrophysics Data System (ADS)

Bowers, Matthew R.

Short-lived radionuclides (SLRs) with lifetimes tau < 100 Ma are known to have been extant when the Solar System formed 4.568 billion years ago from meteoritic studies of their decay products. Identifying the origins of SLRs can provide insight into the origins and timescales of our Solar System and the processes that shaped it. There are two proposed production scenarios for the origins of SLRs with tau < 5 Ma. Freshly synthesized material could be incorporated in the Solar System by a nearby stellar source (e.g., supernova, AGB star, Wolf-Rayet star), or SLRs could have also been produced by the bombardment of gas and dust by solar energetic particles (SEP) emitted by our young Sun. The origin of extinct 36Cl (t1/2 = 0.301 Ma) in the early Solar System is thought to have been produced by local particle irradiation. However the models that attempt to recreate the production of 36Cl in the early Solar System lack experimental data for the nuclear reactions considered. The first measurement of the 33S(alpha,p) 36Cl reaction, an important reaction in the production of 36Cl , was performed. The cross section measurement was performed by bombarding a target and collecting the recoiled 36Cl atoms produced in the reaction, chemically processing the samples, and measuring the 36Cl/Cl concentration of the samples with accelerator mass spectrometry (AMS). The cross section was measured at six energies that ranged from 0.70 up to 2.42 MeV/A, within the SEP energy spectrum. The experimental results were found to be systematically higher than the predicted cross sections. However, the deviations lead to < 7 % increase in total production of 36Cl under the x-wind model. From the experimental measurement and a study of the other reactions' contributions to 36Cl production, 36Cl could have been produced close to the protoSun by reactions on Ca targets using the x-wind model, or in a late-stage irradiation event on a volatile-rich reservoir by 3He and alpha reactions on S targets.

27 CFR 9.12 - AVA petition requirements.

Code of Federal Regulations, 2011 CFR

2011-04-01

... viticulture includes the following: (i) Climate. Temperature, precipitation, wind, fog, solar orientation and radiation, and other climate information; (ii) Geology. Underlying formations, landforms, and such... appellation of origin or in a brand name. (c) Modification of an existing AVA—(1) Boundary change. If a...

Survey of lunar carbon compounds. I - The presence of indigenous gases and hydrolysable carbon compounds in Apollo 11 and Apollo 12 samples

NASA Technical Reports Server (NTRS)

Abell, P. I.; Cadogan, P. H.; Eglinton, G.; Maxwell, J. R.; Pillinger, C. T.

1971-01-01

Indigenous gases and hydrolyzable carbon compounds in Apollo 11 and 12 samples through gas chromatographic and mass spectrometric examination, noting meteoritic impact and solar wind implantation as probable origins

Solar wind structure out of the ecliptic plane over solar cycles

NASA Astrophysics Data System (ADS)

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.

Single ICMEs and Complex Transient Structures in the Solar Wind in 2010 - 2011

NASA Astrophysics Data System (ADS)

Rodkin, D.; Slemzin, V.; Zhukov, A. N.; Goryaev, F.; Shugay, Y.; Veselovsky, I.

2018-05-01

We analyze the statistics, solar sources, and properties of interplanetary coronal mass ejections (ICMEs) in the solar wind. The total number of coronal mass ejections (CMEs) registered in the Coordinated Data Analysis Workshops catalog (CDAW) during the first eight years of Cycle 24 was 61% larger than in the same period of Cycle 23, but the number of X-ray flares registered by the Geostationary Operational Environmental Satellite (GOES) was 20 % smaller because the solar activity was lower. The total number of ICMEs in the given period of Cycle 24 in the Richardson and Cane list was 29% smaller than in Cycle 23, which may be explained by a noticeable number of non-classified ICME-like events in the beginning of Cycle 24. For the period January 2010 - August 2011, we identify solar sources of the ICMEs that are included in the Richardson and Cane list. The solar sources of ICME were determined from coronagraph observations of the Earth-directed CMEs, supplemented by modeling of their propagation in the heliosphere using kinematic models (a ballistic and drag-based model). A detailed analysis of the ICME solar sources in the period under study showed that in 11 cases out of 23 (48%), the observed ICME could be associated with two or more sources. For multiple-source events, the resulting solar wind disturbances can be described as complex (merged) structures that are caused by stream interactions, with properties depending on the type of the participating streams. As a reliable marker to identify interacting streams and their sources, we used the plasma ion composition because it freezes in the low corona and remains unchanged in the heliosphere. According to the ion composition signatures, we classify these cases into three types: complex ejecta originating from weak and strong CME-CME interactions, as well as merged interaction regions (MIRs) originating from the CME high-speed stream (HSS) interactions. We describe temporal profiles of the ion composition for the single-source and multi-source solar wind structures and compared them with the ICME signatures determined from the kinematic and magnetic field parameters of the solar wind. In single-source events, the ion charge state, as a rule, has a one-peak enhancement with an average duration of about one day, which is similar to the mean ICME duration of 1.12 days derived from the Richardson and Cane list. In the multi-source events, the total profile of the ion charge state consists of a sequence of enhancements that is associated with the interaction between the participating streams. On average, the total duration of the complex structures that appear as a result of the CME-CME and CME-HSS interactions as determined from their ion composition is 2.4 days, which is more than twice longer than that of the single-source events.

Earth Science

NASA Image and Video Library

1995-12-01

The reflection of the Atlas IIAS expendable launch vehicle with the Solar Heliospheric Observatory (SOHO) inside its payload fairing can be seen on the surface of a retention pond at Launch Pad 36B on Cape Canaveral Air Station just hours before liftoff. SOHO is a cooperative effort involving NASA and the European Space Agency (ESA) within the framework of the International Solar-Terrestrial Physics Program. During its 2-year mission, the SOHO spacecraft will gather data on the internal structure of the Sun, its extensive outer atmosphere and the origin of the solar wind.

The interaction of the solar wind with the interstellar medium

NASA Technical Reports Server (NTRS)

Axford, W. I.

1972-01-01

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

Neutral Solar Wind Generated by Lunar Exospheric Dust at the Terminator

NASA Technical Reports Server (NTRS)

Collier, Michael R.; Stubbs, Timothy J.

2007-01-01

We calculate the flux of neutral solar wind observed on the lunar surface at the terminator due to solar wind protons penetrating exospheric dust with: (1) grains larger that 0.1 microns and (2) grains larger than 0.01 microns. For grains larger than 0.1 microns, the ratio of the neutral solar wind to solar wind flux is estimated to be approx.10(exp -4)-10(exp -3) at solar wind speeds in excess of 800 km/s, but much lower (less than 10(exp -5) at average to low solar wind speeds. However, when the smaller grain sizes are considered, the ratio of the neutral solar wind flux to solar wind flux is estimated to be greater than or equal to 10(exp -5) at all speeds and at speeds in excess of 700 km/s reaches 10(exp -3)-10(exp -2). These neutral solar wind fluxes are easily measurable with current low energy neutral atom instrumentation. Observations of neutral solar wind from the surface of the Moon could provide a very sensitive determination of the distribution of very small dust grains in the lunar exosphere and would provide data complementary to optical measurements at ultraviolet and visible wavelengths. Furthermore, neutral solar wind, unlike its ionized counterpart, is .not held-off by magnetic anomalies, and may contribute to greater space weathering than expected in certain lunar locations.

Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.

PubMed

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.

Neon isotopes show that Earth was accreted from irradiated material

NASA Astrophysics Data System (ADS)

Moreira, M. A.

2015-12-01

Since the 1980s, the notion that the Earth's mantle has a "solar" isotopic signature for neon has been favoured. Indeed, the 20Ne/22Ne ratio is above 12.5 in the mantle sources of OIB and MORB, close to the solar composition (13.4 for the Sun or 13.8 for the solar wind) and different from both atmospheric and chondritic compositions (Phase Q, Neon A). The most well accepted process invoked to explain this observed solar composition in the mantle is dissolution into a magma ocean of solar gases captured by gravity around the proto-Earth. However, Earth was accreted after gas from the proto-planetary disk had evaporated, suggesting that Earth itself could not have captured such a solar primordial atmosphere. Only planetary embryos were formed when the gas was still present in the disk. However, these planetary embryos with the mass of Mars are not massive enough to capture a solar dense atmosphere able to incorporate enough neon into the mantle. New estimates of the neon isotopic compositions of both the Earth's mantle and of the implanted solar wind into grains suggest that the origin of the neon on Earth is related to solar wind irradiation on μm grains before planetary accretion started and not dissolution. Although incorporation of solar ions by this process is only significant for very volatiles (depleted) elements, the irradiation by x-rays has important consequences for the bulk chemistry of irradiated grains as it has been demonstrated that it produces depletion in Mg and Si, relatively to O (e.g Bradley et al., 1994), a pattern also observed for the Bulk silicate Earth. References Bradley, J. (1994). "Chemically Anomalous, Preaccretionally irradiated Grains in Interplanetary fust from Comets." Science 265: 925-929.

Solar Jets as Sources of Outflows, Heating and Waves

NASA Astrophysics Data System (ADS)

Nishizuka, N.

2013-05-01

Recent space solar observations of the Sun, such as Hinode and SDO, have revealed that magnetic reconnection is ubiquitous in the solar atmosphere, ranging from small scale reconnection (observed as nanoflares) to large scale one (observed as long duration flares or giant arcades). Especially recent Hinode observations has found various types of tiny chromospheric jets, such as chromospheric anemone jets, penumbral microjets and light bridge jets from sunspot umbra. It was also found that the corona is full of tiny X-ray jets. Often they are seen as helical spinning jets with Alfvenic waves in the corona. Sometimes they are seen as chromospheric jets with slow-mode magnetoacoustic waves and sometimes as unresolved jet-like events at the footpoint of recurrent outflows and waves at the edge of the active region. There is increasing evidence of magnetic reconnection in these tiny jets and its association with waves. The origin of outflows and waves is one of the issues concerning coronal heating and solar wind acceleration. To answer this question, we had a challenge to reproduce solar jets with laboratory plasma experiment and directly measured outflows and waves. As a result, we could find a propagating wave excited by magnetic reconnection, whose energy flux is 10% of the released magnetic energy. That is enough for solar wind acceleration and locally enough for coronal heating, consistent with numerical MHD simulations of solar jets. Here we would discuss recent observations with Hinode, theories and experimental results related to jets and waves by magnetic reconnection, and discuss possible implication to reconnection physics, coronal heating and solar wind acceleration.

Near-Mars space

NASA Astrophysics Data System (ADS)

Luhmann, J. G.; Brace, L. H.

1991-05-01

The prevalent attributes of near-Mars space are described: the ambient interplanetary environment, the ionosphere, the upper atmosphere, and more remote regions that are affected by the presence of Mars. The descriptions are based on existing Martian data and/or models constructed from measurements made near Venus. Specific attention is given to the features of solar wind interaction with magnetospheric and ionospheric obstacles. The high-altitude plasma and field environment, the energetic particle environment, the ionosphere environment, and the neutral upper atmosphere environment are described with extensive graphic information, based on existing measurements collected from nine Martian missions. The ionospheric obstacle is assumed to prevail as a mechanism for describing the scenario. Martian perturbation of solar wind is theorized to be of a relatively small order. A distinctive local energetic particle population of planetary origin is shown to result from the direct interaction of solar wind plasma. This phenomenon is considered evidence of the important scavenging of planetary elements from Mars. The absence of a planetary dipole field around Mars, like its low gravity and distance from the sun, is considered important in determining the environment of this earthlike laboratory.

Predicting ICME properties at 1AU

NASA Astrophysics Data System (ADS)

Lago, A.; Braga, C. R.; Mesquita, A. L.; De Mendonça, R. R. S.

2017-12-01

Coronal mass ejections (CMEs) are among the main origins of geomagnetic disturbances. They change the properties of the near-earth interplanetary medium, enhancing some key parameters, such as the southward interplanetary magnetic field and the solar wind speed. Both quantities are known to be related to the energy transfer from the solar wind to the Earth's magnetosphere via the magnetic reconnection process. Many attempts have been made to predict the magnetic filed and the solar wind speed from coronagraph observations. However, we still have much to learn about the dynamic evolution of ICMEs as they propagate through the interplanetary space. Increased observation capability is probably needed. Among the several attempts to establish correlations between CME and ICME properties, it was found that the average CME propagation speed to 1AU is highly correlated to the ICME peak speed (Dal Lago et al, 2004). In this work, we present an extended study of such correlation, which confirms the results found in our previous study. Some suggestions on how to use this kind of results for space weather estimates are explored.

Resolving the Origin of the Diffuse Soft X-ray Background

NASA Technical Reports Server (NTRS)

Smith, Randall K.; Foster, Adam R.; Edgar, Ricard J.; Brickhouse, Nancy S.; Sanders, Wilton T.

2012-01-01

In January 1993, the Diffuse X-ray Spectrometer (DXS) measured the first high-resolution spectrum of the diffuse soft X-ray background between 44-80A. A line-dominated spectrum characteristic of a 10(exp 6)K collisionally ionized plasma' was expected but while the observed spectrum was clearly line-dominated, no model would fit. Then in 2003 the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) launched and observed the diffuse extreme-ultraviolet (EUV) spectrum between 90- 265A. Although many emission lines were again expected; only Fe IX at 171.1A was detected. The discovery of X-rays from comets led to the realization that heavy ions (Z=6-28) in the solar wind will emit soft X-rays as the ions interact via charge exchange with neutral atoms in the heliosphere and geocorona. Using a new model for solar wind charge exchange (SWCX) emission, we show that the diffuse soft X-ray background can be understood as a combination of emission from charge exchange onto the slow and fast solar wind together with a more distant and diffuse hot (10(exp 6)K) plasma.

Seasonal variation of Martian pick-up ions: Evidence of breathing exosphere

NASA Astrophysics Data System (ADS)

Yamauchi, M.; Hara, T.; Lundin, R.; Dubinin, E.; Fedorov, A.; Sauvaud, J.-A.; Frahm, R. A.; Ramstad, R.; Futaana, Y.; Holmstrom, M.; Barabash, S.

2015-12-01

The Mars Express (MEX) Ion Mass Analyser (IMA) found that the detection rate of the ring-like distribution of protons in the solar wind outside of the bow shock to be quite different between Mars orbital summer (around perihelion) and orbital winter (around aphelion) for four Martian years, while the north-south asymmetry is much smaller than the perihelion-aphelion difference. Further analyses using eight years of MEX/IMA solar wind data between 2005 and 2012 has revealed that the detection frequency of the pick-up ions originating from newly ionized exospheric hydrogen with certain flux strongly correlates with the Sun-Mars distance, which changes approximately every two years. Variation due to the solar cycle phase is not distinguishable partly because this effect is masked by the seasonal variation under the MEX capability of plasma measurements. This finding indicates that the variation in solar UV has a major effect on the formation of the pick-up ions, but this is not the only controlling factor.

Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting.

PubMed

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.

Features of solar wind streams on June 21-28, 2015 as a result of interactions between coronal mass ejections and recurrent streams from coronal holes

NASA Astrophysics Data System (ADS)

Shugay, Yu. S.; Slemzin, V. A.; Rod'kin, D. G.

2017-11-01

Coronal sources and parameters of solar wind streams during a strong and prolonged geomagnetic disturbance in June 2015 have been considered. Correspondence between coronal sources and solar wind streams at 1 AU has been determined using an analysis of solar images, catalogs of flares and coronal mass ejections, solar wind parameters including the ionic composition. The sources of disturbances in the considered period were a sequence of five coronal mass ejections that propagated along the recurrent solar wind streams from coronal holes. The observed differences from typical in magnetic and kinetic parameters of solar wind streams have been associated with the interactions of different types of solar wind. The ionic composition has proved to be a good additional marker for highlighting components in a mixture of solar wind streams, which can be associated with different coronal sources.

76 FR 76153 - Notice of Effectiveness of Exempt Wholesale Generator Status; Caney River Wind Project, LLC...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-06

...] Notice of Effectiveness of Exempt Wholesale Generator Status; Caney River Wind Project, LLC, Mesquite Solar 1, LLC, Copper Crossing Solar LLC, Copper Mountain Solar 1, LLC, Pinnacle Wind, LLC, Bellevue Solar, LLC, Yamhill Solar, LLC, Osage Wind, LLC, Minco Wind II, LLC Take notice that during the month of...

Data-Driven Modeling of Solar Corona by a New 3d Path-Conservative Osher-Solomon MHD Odel

NASA Astrophysics Data System (ADS)

Feng, X. S.; Li, C.

2017-12-01

A second-order path-conservative scheme with Godunov-type finite volume method (FVM) has been implemented to advance the equations of single-fluid solar wind plasma magnetohydrodynamics (MHD) in time. This code operates on the six-component composite grid system in 3D spherical coordinates with hexahedral cells of quadrilateral frustum type. The generalized Osher-Solomon Riemann solver is employed based on a numerical integration of the path-dependentdissipation matrix. For simplicity, the straight line segment path is used and the path-integral is evaluated in a fully numerical way by high-order numerical Gauss-Legendre quadrature. Besides its closest similarity to Godunov, the resulting scheme retains the attractive features of the original solver: it is nonlinear, free of entropy-fix, differentiable and complete in that each characteristic field results in a different numerical viscosity, due to the full use of the MHD eigenstructure. By using a minmod limiter for spatial oscillation control, the pathconservative scheme is realized for the generalized Lagrange multiplier (GLM) and the extended generalized Lagrange multiplier (EGLM) formulation of solar wind MHD systems. This new model of second-order in space and time is written in FORTRAN language with Message Passing Interface (MPI) parallelization, and validated in modeling time-dependent large-scale structure of solar corona, driven continuously by the Global Oscillation Network Group (GONG) data. To demonstrate the suitability of our code for the simulation of solar wind, we present selected results from October 9th, 2009 to December 29th, 2009 , & Year 2008 to show its capability of producing structured solar wind in agreement with the observations.

Solar Ion Processing of Itokawa Grains: Constraints on Surface Exposure Times

NASA Technical Reports Server (NTRS)

Christoffersen, R.; Keller, L. P.

2015-01-01

Analytical TEM observations obtained to date reveal that a significant sub-population of grains returned from the surface of asteroid Itokawa have had their outer 30-100 nm processed by space weathering effects. Although the effects include some surface deposition of condensed impact vapor and isolated impact melt splashes, much of the width of the space weathered outer margins or "rims" on grains is derived from solar wind processing of the original host grain. Similar to what has long been reported for some lunar grains, the ion-processed rims on Itokawa grains exhibit varing degrees and depths of penetration of atomic-displacement ion damage, resulting in complete amorphization for some rims (particularly in plagioclase), or formation of highly defective but still crystalline structures in others (particularly in pyroxene and olivine). Possibly different from lunar grains, however, is the presence of isolated internal cavities or voids in Itokawa grain rims, which may be implantation "bubbles" due to accumulating implanted solar wind H and/or He. For a given mineral exposed at a particular set of long term solar wind conditions, the level of ion damage in a given grain rim, the depth of damage penetration represented by the rim width, and the formation or lack of formation of implantation bubbles can all be linked to the time spent by the grain in an uncovered state on the topmost, space-exposed, regolith surface. For the lunar case, we have previously shown that with reasonable assumptions about solar wind characteristics over time, a model can be developed to estimate this exposure time based on the width of amorphous rims on lunar grains. Here we report on an expansion of the model to cover exposure time information contained in the array of solar ion-induced features in Itokawa grains.

27 CFR 9.12 - AVA petition requirements.

Code of Federal Regulations, 2013 CFR

2013-04-01

... viticulture includes the following: (i) Climate. Temperature, precipitation, wind, fog, solar orientation and radiation, and other climate information; (ii) Geology. Underlying formations, landforms, and such... appellation of origin or in a brand name. (c) Modification of an existing AVA.—(1) Boundary change. If a...

27 CFR 9.12 - AVA petition requirements.

Code of Federal Regulations, 2014 CFR

2014-04-01

... viticulture includes the following: (i) Climate. Temperature, precipitation, wind, fog, solar orientation and radiation, and other climate information; (ii) Geology. Underlying formations, landforms, and such... appellation of origin or in a brand name. (c) Modification of an existing AVA.—(1) Boundary change. If a...

27 CFR 9.12 - AVA petition requirements.

Code of Federal Regulations, 2012 CFR

2012-04-01

... viticulture includes the following: (i) Climate. Temperature, precipitation, wind, fog, solar orientation and radiation, and other climate information; (ii) Geology. Underlying formations, landforms, and such... appellation of origin or in a brand name. (c) Modification of an existing AVA.—(1) Boundary change. If a...

Dust Analyzer Instrument (DANTE) for the detection and elemental analysis of dust particles originating from the inner heliosphere

NASA Astrophysics Data System (ADS)

Sternovsky, Z.; O'brien, L.; Gruen, E.; Horanyi, M.; Malaspina, D.; Moebius, E.; Rocha, J. R. R.

2016-12-01

Nano- to sub-micron-size dust particles generated by the collisional breakup of interplanetary dust particles (IDPs) in the inner solar system can be accelerated away from the Sun and are available for detection and analysis near 1 AU. Beta-meteoroids are sub-micron sized particles for which the radiation pressure dominates over gravity and have already been detected by dedicated dust instrument. Charged nano-sized dust particles are picked up by the expanding solar wind and arrive to 1 AU with high velocity. The recent observations by the WAVE instrument on the two STEREO spacecraft indicated that these particles may exist in large numbers. The Dust Analyzer Instrument (DANTE) is specifically developed to detect and analyze these two populations of dust particles arriving from a direction close to the Sun. DANTE is a linear time-of-flight (ToF) mass spectrometer analyzing the ions generated by the dust impact on a target surface. DANTE is derived from the Cosmic Dust Analyzer instrument operating on Cassini. DANTE has a 300 cm2 target area and a mass resolution of approximately m/dm = 50. The instrument performance has been verified using the dust accelerator facility operating at the University of Colorado. A light trap system, consisting of optical baffles, is designed and optimized in terms of geometry and surface optical properties. A solar wind ion repeller system is included to prevent solar wind from entering the sensor. Both measures facilitate the detection with the instrument pointing close to the Sun's direction. The DANTE measurements will help to understand the sources, sinks and distribution of dust between the Sun and 1 AU, and, when combined with solar wind ion analyzer instrument, they will provide insight on the suspected link between dust particles and pickup ions, and how the massive particles affect the dynamics and energetics of the solar wind.

Dynamic molecular oxygen production in cometary comae.

PubMed

Yao, Yunxi; Giapis, Konstantinos P

2017-05-08

Abundant molecular oxygen was discovered in the coma of comet 67P/Churyumov-Gerasimenko. Its origin was ascribed to primordial gaseous O 2 incorporated into the nucleus during the comet's formation. This thesis was put forward after discounting several O 2 production mechanisms in comets, including photolysis and radiolysis of water, solar wind-surface interactions and gas-phase collisions. Here we report an original Eley-Rideal reaction mechanism, which permits direct O 2 formation in single collisions of energetic water ions with oxidized cometary surface analogues. The reaction proceeds by H 2 O + abstracting a surface O-atom, then forming an excited precursor state, which dissociates to produce O 2 - . Subsequent photo-detachment leads to molecular O 2 , whose presence in the coma may thus be linked directly to water molecules and their interaction with the solar wind. This abiotic O 2 production mechanism is consistent with reported trends in the 67P coma and raises awareness of the role of energetic negative ions in comets.

Dynamic molecular oxygen production in cometary comae

NASA Astrophysics Data System (ADS)

Yao, Yunxi; Giapis, Konstantinos P.

2017-05-01

Abundant molecular oxygen was discovered in the coma of comet 67P/Churyumov-Gerasimenko. Its origin was ascribed to primordial gaseous O2 incorporated into the nucleus during the comet's formation. This thesis was put forward after discounting several O2 production mechanisms in comets, including photolysis and radiolysis of water, solar wind-surface interactions and gas-phase collisions. Here we report an original Eley-Rideal reaction mechanism, which permits direct O2 formation in single collisions of energetic water ions with oxidized cometary surface analogues. The reaction proceeds by H2O+ abstracting a surface O-atom, then forming an excited precursor state, which dissociates to produce O2-. Subsequent photo-detachment leads to molecular O2, whose presence in the coma may thus be linked directly to water molecules and their interaction with the solar wind. This abiotic O2 production mechanism is consistent with reported trends in the 67P coma and raises awareness of the role of energetic negative ions in comets.

The Genesis Mission: Contamination Control and Curation

NASA Technical Reports Server (NTRS)

Stansbery, E. K.

2002-01-01

The Genesis mission, launched in August 2001, is collecting samples of the solar wind and will return to Earth in 2004. Genesis can be viewed as the most fundamental of NASA's sample return missions because it is expected to provide insight into the initial elemental and isotopic composition of the solar nebula from which all other planetary objects formed. The data from this mission will have a large impact on understanding the origins and diversity of planetary materials. The collectors consist of clean, pure materials into which the solar wind will imbed. Science and engineering issues such as bulk purity, cleanliness, retention of solar wind, and ability to withstand launch and entry drove material choices. Most of the collector materials are installed on array frames that are deployed from a clean science canister. Two of the arrays are continuously exposed for collecting the bulk solar wind; the other three are only exposed during specific solar wind regimes as measured by ion and electron monitors. Other materials are housed as targets at the focal point of an electrostatic mirror, or "concentrator", designed to enhance the flux of specific solar wind species. Johnson Space Center (JSC) has two principal responsibilities for the Genesis mission: contamination control and curation. Precise and accurate measurements of the composition of the solar atoms require that the collector materials be extremely clean and well characterized before launch and during the mission. Early involvement of JSC curation personnel in concept development resulted in a mission designed to minimize contaminants from the spacecraft and operations. A major goal of the Genesis mission is to provide a reservoir of materials for the 21 51 century. When the collector materials are returned to Earth, they must be handled in a clean manner and their condition well documented. Information gained in preliminary examination of the arrays and detailed surveys of each collector will be used to guide sample allocations to the scientific community. Samples allocated for analysis are likely to be small sections of individual collectors, therefore subdividing the materials must take place in a clean, well characterized way. A major focus of current research at JSC includes identifying and characterizing the contamination, waste, and alteration of the sample when using different subdividing, transport, and storage techniques and developing protocols for reducing their impact on the scientific integrity of the mission.

Surface charging of a crater near lunar terminator

NASA Astrophysics Data System (ADS)

Anuar, A. K.

2017-05-01

Past lunar missions have shown the presence of dust particles in the lunar exosphere. These particles originate from lunar surface and are due to the charging of lunar surface by the solar wind and solar UV flux. Near the lunar terminator region, the low conductivity of the surface and small scale variations in surface topology could cause the surface to charge to different surface potentials. This paper simulates the variation of surface potential for a crater located in the lunar terminator regions using Spacecraft Plasma Interaction Software (SPIS). SPIS employs particle in cell method to simulate the motion of solar wind particles and photoelectrons. Lunar crater has been found to create mini-wake which affects both electron and ion density and causes small scale potential differences. Simulation results show potential difference of 300 V between sunlit area and shadowed area which creates suitable condition for dust levitation to occur.

Magnetic turbulence in a table-top laser-plasma relevant to astrophysical scenarios

NASA Astrophysics Data System (ADS)

Chatterjee, Gourab; Schoeffler, Kevin M.; Kumar Singh, Prashant; Adak, Amitava; Lad, Amit D.; Sengupta, Sudip; Kaw, Predhiman; Silva, Luis O.; Das, Amita; Kumar, G. Ravindra

2017-06-01

Turbulent magnetic fields abound in nature, pervading astrophysical, solar, terrestrial and laboratory plasmas. Understanding the ubiquity of magnetic turbulence and its role in the universe is an outstanding scientific challenge. Here, we report on the transition of magnetic turbulence from an initially electron-driven regime to one dominated by ion-magnetization in a laboratory plasma produced by an intense, table-top laser. Our observations at the magnetized ion scale of the saturated turbulent spectrum bear a striking resemblance with spacecraft measurements of the solar wind magnetic-field spectrum, including the emergence of a spectral kink. Despite originating from diverse energy injection sources (namely, electrons in the laboratory experiment and ion free-energy sources in the solar wind), the turbulent spectra exhibit remarkable parallels. This demonstrates the independence of turbulent spectral properties from the driving source of the turbulence and highlights the potential of small-scale, table-top laboratory experiments for investigating turbulence in astrophysical environments.

Jian Receives 2009 F. L. Scarf Award

NASA Astrophysics Data System (ADS)

2010-03-01

Lan Jian has been awarded the AGU F. L. Scarf Award, given annually to recent Ph.D recipients for outstanding dissertation research that contributes directly to solar planetary sciences. Jian's thesis is entitled “Radial evolution of large-scale solar wind structures.” She was formally presented with the award at the Space Physics and Aeronomy section dinner during the 2009 AGU Fall Meeting, held 14-18 December in San Francisco, Calif. Lan Jian received her B.S. in geophysics from University of Science and Technology of China in 2003. She received her M.S. and Ph.D. degrees in geophysics and space physics, under the supervision of Christopher T. Russell, at University of California, Los Angeles in 2006 and 2008, respectively. Her research interests include various structures in the solar wind, their origin and evolution, and their effect on the space environment of planets.

The Magnetic Connectivity of the Sun to the Heliosphere

NASA Technical Reports Server (NTRS)

Antiochos, S. K.

2010-01-01

A prime research focus of the upcoming Solar Probe Plus and Solar Orbiter missions will be to determine how the heliospheric magnetic field and plasma connect to the Sun's corona and photosphere. For much of the heliosphere this connection appears to be well understood. The quasi-steady fast wind emanates from so-called coronal holes, which appear dark in X-rays and are predominantly unipolar at the photosphere. However, the connection to the Sun of the slow, non-steady wind is far from understood and remains a major mystery. We review the existing theories for the sources of the nonsteady wind and demonstrate that they have difficulty accounting for both the observed composition of the wind and its large angular extent. A new theory is described in which this wind originates from the continuous opening and closing of narrow open field corridors in the corona, which gives rise to a web of separatrices (the S-Web) in the heliosphere. Note that in this theory the corona - heliosphere connection is intrinsically dynamic, at least, for this type of wind. We present numerical simulations of the model and describe observational tests. We discuss the implications of our results for the competing slow wind theories and for understanding the corona - heliosphere connection, in general.

Western Wind and Solar Integration Study | Grid Modernization | NREL

Science.gov Websites

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

Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting

PubMed Central

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

KSC-97PC1013

NASA Image and Video Library

1997-07-02

Workers from the Johns Hopkins University’s Applied Physics Laboratory (APL) install the Cosmic Ray Isotope Spectrometer (CRIS) on the Advanced Composition Explorer (ACE) spacecraft in KSC’s Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2). From left, are Al Sadilek, Marcos Gonzalez and Cliff Willey. CRIS is one of nine instruments on ACE, which will investigate the origin and evolution of solar phenomenon, the formation of the solar corona, solar flares and the acceleration of the solar wind. ACE was developed for NASA by the APL. The spacecraft is scheduled to be launched Aug. 21 aboard a two-stage Delta II 7920-8 rocket from Space Launch Complex 17, Pad A

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

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-18

... Delta LLC; Mountain View Solar, LLC; Pheasant Run Wind, LLC; Pheasant Run Wind II, LLC; Tuscola Wind II, LLC; Mountain Wind Power, LLC; Mountain Wind Power II, LLC; Summerhaven Wind, LP; Notice of...

O+ pickup ions outside of Venus' bow shock: Venus Express observation

NASA Astrophysics Data System (ADS)

Wei, Y.; Fraenz, M.; Dubinin, E.; Zhang, T. L.; Wan, W.; Barabash, S.; Woch, J.; Lundin, R.

2012-09-01

Pickup ions are ions of planetary origin that become assimilated into the solar wind flow through their interaction with the solar wind magnetic and electric field. The speed of pickup ions varies between zero and twice the underlying plasma flow component perpendicular to magnetic field vector. For the unmagnetized planet Venus and Mars, oxygen (O+) pickup ions are known to be important because they can modify the global configuration of planetary plasma environment and significantly contribute to the atmospheric O+ loss [1]. Since the kinetic energy of an O+ pickup ion can reach 64 times that of a co-moving proton, an instrument must be able to measure O+ ions with energy of at least tens of keV to investigate the O+ pickup ion distribution from planetary ionosphere to solar wind. The in-situ observations and simulations at Mars have shown that the energy of O+ pickup ions can be 55-72 keV outside of the bow shock [2]. For Venus case, the plasma analyzer (OPA) onboard Pioneer Venus Orbiter (PVO), which was designed for solar wind monitoring, has an 8 keV energy limit for O+ detection and the limited sampling and data rate [3]. Therefore, OPA can only measure the O+ pickup ions in the sheath flow or inside the induced magnetosphere where the speed of ambient plasma flow is significantly lower than that of the unshocked solar wind outside of the bow shock. The Ion Mass Analyzer (IMA), included in the Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) package on board Venus Express (VEX), determines the composition, energy, and angular distribution of ions in the energy range ~10 eV/q to 30 keV/q. Note that an O+ ion moving at the typical solar wind speed 400 km/s has kinetic energy 13.4 keV. Therefore, IMA has ability to measure the O+ pickup ions outside of Venus' bow shock. We have examined the IMA data during the solar minimum period 2006-2010, and identified about ten cases with clear signature of O+ pickup ion. With these observations, we will determine the location and the scale height of the source region of O+ pickup ions and describe the relationship between the behavior of these O+ and the upstream solar wind condition. The results would provide new information for numerical simulation of plasma environment near Venus and contribute to estimation of total O+ ion loss from Venus.

Mass-loading of the solar wind at 67P/Churyumov-Gerasimenko. Observations and modelling

NASA Astrophysics Data System (ADS)

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.

Hydromagnetic waves, turbulence, and collisionless processes in the interplanetary medium

NASA Technical Reports Server (NTRS)

Barnes, A.

1983-01-01

An extended discussion is conducted concerning the origin and evolution of interplanetary hydromagnetic waves and turbulence, and their influence on the large scale dynamics of the solar wind. The solar wind is at present the preeminent medium for the study of hydromagnetic waves and turbulence, providing an opportunity for advancement of understanding of the most fundamental processes of the astrophysical plasmas. All interplanetary fluctuations whose time scale is observed to be greater than 1 sec can be regarded as hydromagnetic fluctuations. It has been found to be simplest, and generally very satisfactory, to model interplanetary variations as fluctuations in an MHD fluid. Attention is given to the classification of wave modes, geometrical hydromagnetics, Alfven wave pressure, rugged invariants, and the kinetic theory of collisionless processes.

Comparison of Magnetospheric Multiscale Ion Jet Signatures with Predicted Reconnection Site Locations at the Magnetopause

NASA Technical Reports Server (NTRS)

Petrinec, S. M.; Burch, J. L.; Fuselier, S. A.; Gomez, R. G.; Lewis, W.; Trattner, K. J.; Ergun, R.; Mauk, B.; Pollock, C. J.; Schiff, C.;

Electron-Ion Intensity Dropouts in Gradual Solar Energetic Particle Events during Solar Cycle 23

NASA Astrophysics Data System (ADS)

Tan, Lun C.

2017-09-01

Since the field-line mixing model of Giacalone et al. suggests that ion dropouts cannot happen in the “gradual” solar energetic particle (SEP) event because of the large size of the particle source region in the event, the observational evidence of ion dropouts in the gradual SEP event should challenge the model. We have searched for the presence of ion dropouts in the gradual SEP event during solar cycle 23. From 10 SEP events the synchronized occurrence of ion and electron dropouts is identified in 12 periods. Our main observational facts, including the mean width of electron-ion dropout periods being consistent with the solar wind correlation scale, during the dropout period the dominance of the slab turbulence component and the enhanced turbulence power parallel to the mean magnetic field, and the ion gyroradius dependence of the edge steepness in dropout periods, are all in support of the solar wind turbulence origin of dropout events. Also, our observation indicates that a wide longitude distribution of SEP events could be due to the increase of slab turbulence fraction with the increased longitude distance from the flare-associated active region.

Numerical simulation of wind loads on solar panels

NASA Astrophysics Data System (ADS)

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.

On the physics of waves in the solar atmosphere: Wave heating and wind acceleration

NASA Technical Reports Server (NTRS)

Musielak, Z. E.

1992-01-01

In the area of solar physics, new calculations of the acoustic wave energy fluxes generated in the solar convective zone was performed. The original theory developed was corrected by including a new frequency factor describing temporal variations of the turbulent energy spectrum. We have modified the original Stein code by including this new frequency factor, and tested the code extensively. Another possible source of the mechanical energy generated in the solar convective zone is the excitation of magnetic flux tube waves which can carry energy along the tubes far away from the region. The problem as to how efficiently those waves are generated in the Sun was recently solved. The propagation of nonlinear magnetic tube waves in the solar atmosphere was calculated, and mode coupling, shock formation, and heating of the local medium was studied. The wave trapping problems and evaluation of critical frequencies for wave reflection in the solar atmosphere was studied. It was shown that the role played by Alfven waves in the wind accelerations and the coronal hole heating is dominant. Presently, we are performing calculations of wave energy fluxes generated in late-type dwarf stars and studying physical processes responsible for the heating of stellar chromospheres and coronae. In the area of physics of waves, a new analytical approach for studying linear Alfven waves in smoothly nonuniform media was recently developed. This approach is presently being extended to study the propagation of linear and nonlinear magnetohydrodynamic (MHD) waves in stratified, nonisothermal and solar atmosphere. The Lighthill theory of sound generation to nonisothermal media (with a special temperature distribution) was extended. Energy cascade by nonlinear MHD waves and possible chaos driven by these waves are presently considered.

Flow direction variations of low energy ions as measured by the ion electron sensor (IES) flying on board of Rosetta

NASA Astrophysics Data System (ADS)

Szegö, Karoly; Nemeth, Zoltan; Foldy, Lajos; Burch, James L.; Goldstein, Raymond; Mandt, Kathleen; Mokashi, Prachet; Broiles, Tom

2015-04-01

The Ion Electron Sensor (IES) simultaneously measures ions and electrons with two separate electrostatic plasma analyzers in the energy range of 4 eV- 22 keV for ions. The field of view is 90ox360o, with angular resolution 5ox45o for ions, with a sector containing the solar wind being further segmented to 5o × 5o. IES has operated continuously since early 2014. In the ion data a low energy (<50-100 eV) component is well separated from the higher energy ions. Here we analyze the arrival direction of this low energy component. The origin of these low energy ions is certainly the ionized component of the neutral gas emitted due to solar activity from comet 67P/Churiumov-Gerasimenko. The low energy component in general shows a 6h periodicity due to cometary rotation. The data show, however, that the arrival direction of the low energy ions is smeared both in azimuth and elevation, due possibly to the diverse mechanisms affecting these ions. One of these effects is the spacecraft potential (~-10V), which accelerates the ions towards the spacecraft omnidirectionally. To characterize the flow direction in azimuth-elevation, we have integrated over the lowest 8 energy channels using weighted energy: sum(counts * energy)/sum(counts); and considered only cases when the counts are above 30. When we apply higher cut for counts, the flow direction became more definite. For this analysis we use data files where the two neighbouring energy values and elevation values are collapsed; and the azimuthal resolution is 45o, that is the solar wind azimuthal segmentation is also collapsed. Here we use day 2014.09.11. as illustration. On that day a solar wind shock reached the spacecraft at about ~10 UT. After the shock transition the energy of the solar wind became higher, and after ~12 UT the flow direction of the solar wind fluctuated, sometimes by 35o. On this day Rosetta flew at about 29.3-29.6 km from the nucleus. In the azimuth-elevation plots summed over "weighted energy" (as defined above) we were able to identify two flow directions: one close to the anti-solar direction, and one perpendicular to it. The occurrence and variations of these directions are still under investigation. A possible cause of the acceleration of low energy ions along the solar wind might be that electrons produced by the ionization of neutrals are immediately picked up by the solar wind generating a polarization electric field that accelerates the ions. This effect is similar to the generation of ionospheric holes at Venus [Hartle and Grebowsky, Adv. Space Res., 4, 1995]. The acceleration perpendicular to the solar wind might be due to the v x B electric field. The variations of the low energy flow direction is analyzed in detail in the presentation.

Improvement of background solar wind predictions

NASA Astrophysics Data System (ADS)

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.

Microphysics of Waves and Instabilities in the Solar Wind and Their Macro Manifestations in the Corona and Interplanetary Space

NASA Technical Reports Server (NTRS)

Habbal, Shadia Rifai

2005-01-01

Investigations of the physical processes responsible for coronal heating and the acceleration of the solar wind were pursued with the use of our recently developed 2D MHD solar wind code and our 1D multifluid code. In particular, we explored: (1) the role of proton temperature anisotropy in the expansion of the solar (2) the role of plasma parameters at the coronal base in the formation of high (3) a three-fluid model of the slow solar wind (4) the heating of coronal loops (5) a newly developed hybrid code for the study of ion cyclotron resonance in wind, speed solar wind streams at mid-latitudes, the solar wind.

Unified Models of Turbulence and Nonlinear Wave Evolution in the Extended Solar Corona and Solar Wind

NASA Technical Reports Server (NTRS)

Cranmer, Steven R.; Wagner, William (Technical Monitor)

2004-01-01

The PI (Cranmer) and Co-I (A. van Ballegooijen) made substantial progress toward the goal of producing a unified model of the basic physical processes responsible for solar wind acceleration. The approach outlined in the original proposal comprised two complementary pieces: (1) to further investigate individual physical processes under realistic coronal and solar wind conditions, and (2) to extract the dominant physical effects from simulations and apply them to a 1D model of plasma heating and acceleration. The accomplishments in Year 2 are divided into these two categories: 1a. Focused Study of Kinetic Magnetohydrodynamic (MHD) Turbulence. lb. Focused Study of Non - WKB Alfven Wave Rejection. and 2. The Unified Model Code. We have continued the development of the computational model of a time-study open flux tube in the extended corona. The proton-electron Monte Carlo model is being tested, and collisionless wave-particle interactions are being included. In order to better understand how to easily incorporate various kinds of wave-particle processes into the code, the PI performed a detailed study of the so-called "Ito Calculus", i.e., the mathematical theory of how to update the positions of particles in a probabilistic manner when their motions are governed by diffusion in velocity space.

11- and 22-year variations of the cosmic ray density and of the solar wind speed

NASA Technical Reports Server (NTRS)

Chirkov, N. P.

1985-01-01

Cosmic ray density variations for 17-21 solar activity cycles and the solar wind speed for 20-21 events are investigated. The 22-year solar wind speed recurrence was found in even and odd cycles. The 22-year variations of cosmic ray density were found to be opposite that of solar wind speed and solar activity. The account of solar wind speed in 11-year variations significantly decreases the modulation region of cosmic rays when E = 10-20 GeV.

Correlations between solar wind parameters and auroral kilometric radiation intensity

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Dangelo, N.

1981-01-01

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

Solar wind interaction effects on the magnetic fields around Mars: Consequences for interplanetary and crustal field measurements

NASA Astrophysics Data System (ADS)

Luhmann, J. G.; Ma, Y.-J.; Brain, D. A.; Ulusen, D.; Lillis, R. J.; Halekas, J. S.; Espley, J. R.

2015-11-01

The first unambiguous detections of the crustal remanent magnetic fields of Mars were obtained by Mars Global Surveyor (MGS) during its initial orbits around Mars, which probed altitudes to within ∼110 km of the surface. However, the majority of its measurements were carried out around 400 km altitude, fixed 2 a.m. to 2 p.m. local time, mapping orbit. While the general character and planetary origins of the localized crustal fields were clearly revealed by the mapping survey data, their effects on the solar wind interaction could not be investigated in much detail because of the limited mapping orbit sampling. Previous analyses (Brain et al., 2006) of the field measurements on the dayside nevertheless provided an idea of the extent to which the interaction of the solar wind and planetary fields leads to non-ideal field draping at the mapping altitude. In this study we use numerical simulations of the global solar wind interaction with Mars as an aid to interpreting that observed non-ideal behavior. In addition, motivated by models for different interplanetary field orientations, we investigate the effects of induced and reconnected (planetary and external) fields on the Martian field's properties derived at the MGS mapping orbit altitude. The results suggest that inference of the planetary low order moments is compromised by their influence. In particular, the intrinsic dipole contribution may differ from that in the current models because the induced component is so dominant.

Solar and Interplanetary Sources of Major Geomagnetic Storms (Dst less than or equal to -100 nT) During 1996 - 2005

NASA Technical Reports Server (NTRS)

Zhang, J.; Richardson, I.; Webb, D. F.; Gopalswamy, N.; Huttunen, E.; Kasper, J.; Nitta, N.; Poomvises, W.; Thompson, B. J.; Wu, C.-C.;

Coronal holes as sources of solar wind

NASA Technical Reports Server (NTRS)

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.

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

NASA Technical Reports Server (NTRS)

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

2013-01-01

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

Analysis of the solar/wind resources in Southern Spain for optimal sizing of hybrid solar-wind power generation systems

NASA Astrophysics Data System (ADS)

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.

Clues From Pluto's Ions

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-05-01

Nearly a year ago, in July 2015, the New Horizons spacecraft passed by the Pluto system. The wealth of data amassed from that flyby is still being analyzed including data from the Solar Wind Around Pluto (SWAP) instrument. Recent examination of this data has revealedinteresting new information about Plutos atmosphere and how the solar wind interacts with it.A Heavy Ion TailThe solar wind is a constant stream of charged particles released by the Sun at speeds of around 400 km/s (thats 1 million mph!). This wind travels out to the far reaches of the solar system, interacting with the bodies it encounters along the way.By modeling the SWAP detections, the authors determine the directions of the IMF that could produce the heavy ions detected. Red pixels represent IMF directions permitted. No possible IMF could reproduce the detections if the ions are nitrogen (bottom panels), and only retrograde IMF directions can produce the detections if the ions are methane. [Adapted from Zirnstein et al. 2016]New Horizons data has revealed that Plutos atmosphere leaks neutral nitrogen, methane, and carbon monoxide molecules that sometimes escape its weak gravitational pull. These molecules become ionized and are subsequently picked up by the passing solar wind, forming a tail of heavy ions behind Pluto. The details of the geometry and composition of this tail, however, had not yet been determined.Escaping MethaneIn a recent study led by Eric Zirnstein (Southwest Research Institute), the latest analysis of data from the SWAP instrument on board New Horizons is reported. The team used SWAPs ion detections from just after New Horizons closest approach to Pluto to better understand how the heavy ions around Pluto behave, and how the solar wind interacts with Plutos atmosphere.In the process of analyzing the SWAP data, Zirnstein and collaborators first establish what the majority of the heavy ions picked up by the solar wind are. Models of the SWAP detections indicate they are unlikely to be nitrogen ions, despite nitrogen being the most abundant molecule in Plutos atmosphere. Instead, the detections are likely of methane ions possibly present because methane molecules are lighter, allowing them to more efficiently escape Plutos atmosphere.Reconstructed origins of heavy ions detected by SWAP shortly after New Horizons closest approach to Pluto. Color represents the energy at the time of detection. [Adapted from Zirnstein et al. 2016]Magnetic DirectionNew Horizons does not have a magnetometer on board, which prevented it from making direct measurements of the interplanetary magnetic field (IMF; the solar magnetic field extended throughout the solar system) during the Pluto encounter. In spite of this, Zirnstein and collaborators are able to determine the IMF direction using some clever calculations about SWAPs field of view and the energies of heavy ions it detected.They demonstrate that the IMF was likely oriented roughly parallel to the ecliptic plane, and in the opposite direction of Plutos orbital motion, during New Horizons Pluto encounter. This would cause the solar wind to deflect southward around Pluto, resulting in a north-south asymmetry in the heavy ion tail behind Pluto.The new knowledge gained from SWAP about the geometry and the composition of Plutos extended atmosphere will help us to interpret further data from New Horizons. Ultimately, this provides us with a better understanding both of Plutos atmosphere and how the solar wind interacts with bodies in our solar system.CitationE. J. Zirnstein et al 2016 ApJ 823 L30. doi:10.3847/2041-8205/823/2/L30

Depth profiling analysis of solar wind helium collected in diamond-like carbon film from Genesis

DOE PAGES

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

The Solar Wind Ion Composition Spectrometer

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

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

NASA Technical Reports Server (NTRS)

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.

Global Solar Magnetic Field Organization in the Outer Corona: Influence on the Solar Wind Speed and Mass Flux Over the Cycle

NASA Astrophysics Data System (ADS)

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}⊙ .

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

NASA Technical Reports Server (NTRS)

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

2004-01-01

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

New equipment the ion beam irradiation equipment installed at ISAS / JAXA

NASA Astrophysics Data System (ADS)

Nakauchi, Yusuke; Matsumoto, Toru; Asada, Yuma; Abe, Masanao; Tsuchiyama, Akira; Takigawa, Aki; Watanabe, Naoki; Yusuke Nakauchi

2017-10-01

Understanding of the space weathering effect by the solar wind implantation is thought to be important for the interpretation of the reflectance spectra on the airless body’s surface [e.g. 1]. It is important to elucidate the space weathering effect by hydrogen ions and helium ions which account for most of solar wind. In particular, it is suggested that the solar wind protons interact with the minerals in the surface layer of the airless bodies to form OH and H2O. To understanding the space weathering effect by solar wind protons will be an important clue to reveal the origin and the abundance of lunar water [e.g. 2].Solar wind consists of 95% protons, 4% helium and other ions [3]. The energy of protons is mainly 1.1 keV and the one of helium ions is mainly 4 keV. Then, we established the ion beam irradiation equipment in ISAS/JAXA. This device consists of a cold cathode ion gun, an ion irradiation chamber, a load lock chamber for specimen preparation and reflection spectrum measurement, and FTIR. The ion sources capable of irradiation are hydrogen and helium which occupy the most of solar wind and it is possible to selectively irradiate each ion with a magnetic separator. The energy can be selected from 500 eV to 5 keV. The ultimate degree of vacuum is about 10-6 Pa. The samples can move between the irradiation chamber and the load lock chamber without being exposed to the air. Moreover, since the nitrogen purge is possible for the optical path of FTIR, the influence of the adsorbed water can be ignored when measuring the reflection spectra.In this presentation, we will report the first results of the performance of ion beam irradiation equipment (e.g. beam current, beam-shape) and the proton irradiation to Sun Carlos olivine.[1] T. Noguchi et al., MPS, 49(2):188-214, 2014. [2] C.M. Pieters et al., Science, 326(5952):568-572, 2009. [3] J.T. Gosling, Encyclopedia of the Solar System (Second Edition), pages 99 -116, 2007. Acknowledgements Part of this work has been supported by the Japan Society for the Promotion of Science KAKENHI Grant Numbers JP15H05695, JP16H04044, Core-to-Core program (International Network of Planetary Sciences).

Anisotropic Solar Wind Sputtering of the Lunar Surface Induced by Crustal Magnetic Anomalies

NASA Technical Reports Server (NTRS)

Poppe, A. R.; Sarantos, M.; Halekas, J. S.; Delory, G. T.; Saito, Y.; Nishino, M.

2014-01-01

The lunar exosphere is generated by several processes each of which generates neutral distributions with different spatial and temporal variability. Solar wind sputtering of the lunar surface is a major process for many regolith-derived species and typically generates neutral distributions with a cosine dependence on solar zenith angle. Complicating this picture are remanent crustal magnetic anomalies on the lunar surface, which decelerate and partially reflect the solar wind before it strikes the surface. We use Kaguya maps of solar wind reflection efficiencies, Lunar Prospector maps of crustal field strengths, and published neutral sputtering yields to calculate anisotropic solar wind sputtering maps. We feed these maps to a Monte Carlo neutral exospheric model to explore three-dimensional exospheric anisotropies and find that significant anisotropies should be present in the neutral exosphere depending on selenographic location and solar wind conditions. Better understanding of solar wind/crustal anomaly interactions could potentially improve our results.

Observations of micro-turbulence in the solar wind near the sun with interplanetary scintillation

NASA Technical Reports Server (NTRS)

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.

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

NASA Astrophysics Data System (ADS)

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 heliosphere confined to the ecliptic region is derived, accounting for solar activity and for solar distance through adequate shifts of the lognormal distributions. Finally, the inclusion of SSN predictions and the extrapolation down to PSPs perihelion region enables us to estimate the solar-wind environment for PSPs planned trajectory during its mission duration. Results: The CGAUSS empirical solar-wind model for PSP yields dependencies on solar activity and solar distance for the solar-wind parameters' frequency distributions. The estimated solar-wind median values for PSPs first perihelion in 2018 at a solar distance of 0.16 au are 87 nT, 340 km s-1, 214 cm-3, and 503 000 K. The estimates for PSPs first closest perihelion, occurring in 2024 at 0.046 au (9.86 R⊙), are 943 nT, 290 km s-1, 2951 cm-3, and 1 930 000 K. Since the modeled velocity and temperature values below approximately 20 R⊙appear overestimated in comparison with existing observations, this suggests that PSP will directly measure solar-wind acceleration and heating processes below 20 R⊙ as planned.

Polar solar wind and interstellar wind properties from interplanetary Lyman-alpha radiation measurements

NASA Technical Reports Server (NTRS)

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.

The solar wind-magnetosphere-ionosphere system

PubMed

Lyon

2000-06-16

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

Correlating Solar Wind Modulation with Ionospheric Variability at Mars from MEX and MAVEN Observations

NASA Astrophysics Data System (ADS)

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.

Solar wind structure suggested by bimodal correlations of solar wind speed and density between the spacecraft SOHO and Wind

NASA Astrophysics Data System (ADS)

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.

Sources of Geomagnetic Activity during Nearly Three Solar Cycles (1972-2000)

NASA Technical Reports Server (NTRS)

Richardson, I. G.; Cane, H. V.; Cliver, E. W.; White, Nicholas E. (Technical Monitor)

2002-01-01

We examine the contributions of the principal solar wind components (corotating highspeed streams, slow solar wind, and transient structures, i.e., interplanetary coronal mass ejections (CMEs), shocks, and postshock flows) to averages of the aa geomagnetic index and the interplanetary magnetic field (IMF) strength in 1972-2000 during nearly three solar cycles. A prime motivation is to understand the influence of solar cycle variations in solar wind structure on long-term (e.g., approximately annual) averages of these parameters. We show that high-speed streams account for approximately two-thirds of long-term aa averages at solar minimum, while at solar maximum, structures associated with transients make the largest contribution (approx. 50%), though contributions from streams and slow solar wind continue to be present. Similarly, high-speed streams are the principal contributor (approx. 55%) to solar minimum averages of the IMF, while transient-related structures are the leading contributor (approx. 40%) at solar maximum. These differences between solar maximum and minimum reflect the changing structure of the near-ecliptic solar wind during the solar cycle. For minimum periods, the Earth is embedded in high-speed streams approx. 55% of the time versus approx. 35% for slow solar wind and approx. 10% for CME-associated structures, while at solar maximum, typical percentages are as follows: high-speed streams approx. 35%, slow solar wind approx. 30%, and CME-associated approx. 35%. These compositions show little cycle-to-cycle variation, at least for the interval considered in this paper. Despite the change in the occurrences of different types of solar wind over the solar cycle (and less significant changes from cycle to cycle), overall, variations in the averages of the aa index and IMF closely follow those in corotating streams. Considering solar cycle averages, we show that high-speed streams account for approx. 44%, approx. 48%, and approx. 40% of the solar wind composition, aa, and the IMF strength, respectively, with corresponding figures of approx. 22%, approx. 32%, and approx. 25% for CME-related structures, and approx. 33%, approx. 19%, and approx. 33% for slow solar wind.

Transport of solar wind into Earth's magnetosphere through rolled-up Kelvin-Helmholtz vortices.

PubMed

Hasegawa, H; Fujimoto, M; Phan, T-D; Rème, H; Balogh, A; Dunlop, M W; Hashimoto, C; Tandokoro, R

2004-08-12

Establishing the mechanisms by which the solar wind enters Earth's magnetosphere is one of the biggest goals of magnetospheric physics, as it forms the basis of space weather phenomena such as magnetic storms and aurorae. It is generally believed that magnetic reconnection is the dominant process, especially during southward solar-wind magnetic field conditions when the solar-wind and geomagnetic fields are antiparallel at the low-latitude magnetopause. But the plasma content in the outer magnetosphere increases during northward solar-wind magnetic field conditions, contrary to expectation if reconnection is dominant. Here we show that during northward solar-wind magnetic field conditions-in the absence of active reconnection at low latitudes-there is a solar-wind transport mechanism associated with the nonlinear phase of the Kelvin-Helmholtz instability. This can supply plasma sources for various space weather phenomena.

On the Role of Interchange Reconnection in the Generation of the Slow Solar Wind

NASA Astrophysics Data System (ADS)

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.

Land-Use Intensity of Electricity Production: Comparison Across Multiple Sources

NASA Astrophysics Data System (ADS)

Swain, M.; Lovering, J.; Blomqvist, L.; Nordhaus, T.; Hernandez, R. R.

2015-12-01

Land is an increasingly scarce global resource that is subject to competing pressures from agriculture, human settlement, and energy development. As countries concerned about climate change seek to decarbonize their power sectors, renewable energy sources like wind and solar offer obvious advantages. However, the land needed for new energy infrastructure is also an important environmental consideration. The land requirement of different electricity sources varies considerably, but there are very few studies that offer a normalized comparison. In this paper, we use meta-analysis to calculate the land-use intensity (LUI) of the following electricity generation sources: wind, solar photovoltaic (PV), concentrated solar power (CSP), hydropower, geothermal, nuclear, biomass, natural gas, and coal. We used data from existing studies as well as original data gathered from public records and geospatial analysis. Our land-use metric includes land needed for the generation facility (e.g., power plant or wind farm) as well as the area needed to mine fuel for natural gas, coal, and nuclear power plants. Our results found the lowest total LUI for nuclear power (115 ha/TWh/y) and the highest LUI for biomass (114,817 ha/TWh/y). Solar PV and CSP had a considerably lower LUI than wind power, but both were an order of magnitude higher than fossil fuels (which ranged from 435 ha/TWh/y for natural gas to 579 ha/TWh/y for coal). Our results suggest that a large build-out of renewable electricity, though it would offer many environmental advantages over fossil fuel power sources, would require considerable land area. Among low-carbon energy sources, relatively compact sources like nuclear and solar have the potential to reduce land requirements.

Genesis Solar Wind Interstream, Coronal Hole and Coronal Mass Ejection Samples: Update on Availability and Condition

NASA Technical Reports Server (NTRS)

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

2017-01-01

Recent refinement of analysis of ACE/SWICS data (Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer) and of onboard data for Genesis Discovery Mission of 3 regimes of solar wind at Earth-Sun L1 make it an appropriate time to update the availability and condition of Genesis samples specifically collected in these three regimes and currently curated at Johnson Space Center. ACE/SWICS spacecraft data indicate that solar wind flow types emanating from the interstream regions, from coronal holes and from coronal mass ejections are elementally and isotopically fractionated in different ways from the solar photosphere, and that correction of solar wind values to photosphere values is non-trivial. Returned Genesis solar wind samples captured very different kinds of information about these three regimes than spacecraft data. Samples were collected from 11/30/2001 to 4/1/2004 on the declining phase of solar cycle 23. Meshik, et al is an example of precision attainable. Earlier high precision laboratory analyses of noble gases collected in the interstream, coronal hole and coronal mass ejection regimes speak to degree of fractionation in solar wind formation and models that laboratory data support. The current availability and condition of samples captured on collector plates during interstream slow solar wind, coronal hole high speed solar wind and coronal mass ejections are de-scribed here for potential users of these samples.

KSC-98pc1133

NASA Image and Video Library

1998-09-18

KENNEDY SPACE CENTER, FLA. -- The Spartan solar-observing deployable spacecraft is placed inside the payload canister in the Multi-Payload Processing Facility at KSC. Spartan is one of the payloads for the STS-95 mission, scheduled to launch Oct. 29. Spartan is a solar physics spacecraft designed to perform remote sensing of the hot outer layers of the sun's atmosphere or corona. The objective of the observations is to investigate the mechanisms causing the heating of the solar corona and the acceleration of the solar wind which originates in the corona. Other research payloads include the Hubble Space Telescope Orbital Systems Test Platform, the International Extreme Ultraviolet Hitchhiker, and the SPACEHAB single module with experiments on space flight and the aging process

KSC-98pc1132

NASA Image and Video Library

1998-09-18

KENNEDY SPACE CENTER, FLA. -- The Spartan solar-observing deployable spacecraft is suspended above the payload canister in the Multi-Payload Processing Facility at KSC. Spartan is one of the payloads for the STS-95 mission, scheduled to launch Oct. 29. Spartan is a solar physics spacecraft designed to perform remote sensing of the hot outer layers of the sun's atmosphere or corona. The objective of the observations is to investigate the mechanisms causing the heating of the solar corona and the acceleration of the solar wind which originates in the corona. Other research payloads include the Hubble Space Telescope Orbital Systems Test Platform, the International Extreme Ultraviolet Hitchhiker, and the SPACEHAB single module with experiments on space flight and the aging process

KSC-97PC1287

NASA Image and Video Library

1997-08-24

After launch tower retraction, the Boeing Delta II expendable launch vehicle carrying the Advanced Composition Explorer (ACE) undergoes final preparations for liftoff in the predawn hours of Aug. 24, 1997, at Launch Complex 17A, Cape Canaveral Air Station. This is the second Delta launch under the Boeing name and the first from Cape Canaveral. ACE with its combination of nine sensors and instruments will investigate the origin and evolution of solar phenomenon, the formation of solar corona, solar flares and acceleration of the solar wind. ACE was built for NASA by the Johns Hopkins Applied Physics Laboratory and is managed by the Explorer Project Office at NASA’s Goddard Space Flight Center. The lead scientific institution is the California Institute of Technology

Solar and Wind Forecasting | Grid Modernization | NREL

Science.gov Websites

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

Electromagnetic Electron Cyclotron Instability in the Solar Wind

NASA Astrophysics Data System (ADS)

Lazar, M.; Yoon, P. H.; López, R. A.; Moya, P. S.

2018-01-01

The abundant reports on the existence of electromagnetic high-frequency fluctuations in space plasmas have increased the expectations that theoretical modeling may help understand their origins and implications (e.g., kinetic instabilities and dissipation). This paper presents an extended quasi-linear approach of the electromagnetic electron cyclotron instability in conditions typical for the solar wind, where the anisotropic electrons (T⊥>T∥) exhibit a dual distribution combining a bi-Maxwellian core and bi-Kappa halo. Involving both the core and halo populations, the instability is triggered by the cumulative effects of these components, mainly depending of their anisotropies. The instability is not very sensitive to the shape of halo distribution function conditioned in this case by the power index κ. This result seems to be a direct consequence of the low density of electron halo, which is assumed more dilute than the core component in conformity with the observations in the ecliptic. Quasi-linear time evolutions predicted by the theory are confirmed by the particle-in-cell simulations, which also suggest possible explanations for the inherent differences determined by theoretical constraints. These results provide premises for an advanced methodology to characterize, realistically, the electromagnetic electron cyclotron instability and its implication in the solar wind.

Source of Volatiles in Earth's Deep Mantle from Neon Isotope Systematics in the South Atlantic

NASA Astrophysics Data System (ADS)

Williams, C. D.; Mukhopadhyay, S.

2016-12-01

The noble gases play an important role in understanding Earth's accretion and subsequent evolution. Neon isotopes in particular have the potential to distinguish between distinct sources of Earth's volatiles e.g., acquisition of nebular gas, solar wind implanted materials or chondritic meteorites and their components. The neon isotopic composition of the deep mantle remains subject to debate with the majority of mantle-derived basalts displaying maximum 20Ne/22Ne ratios less than 12.5, similar to values determined for the convective mantle (20Ne/22Ne = 12.49 +/- 0.04; [1]). These values are also much lower than those of solar wind (20Ne/22Ne = 13.8; [2,3]) and estimates of the nebular gas (20Ne/22Ne = 13.4; [4]) but comparable to solar wind implanted meteoritic materials (20Ne/22Ne = 12.5-12.7; [5]). Here we determine the neon isotopic composition of mantle-derived materials from the south Atlantic. These samples display strong linear correlations in 20Ne/22Ne-21Ne/22Ne space with maximum 20Ne/22Ne ratios that are resolvable from and higher than materials derived from the convecting mantle as well as models of solar wind implantation. These results supplement a growing database of mantle materials characterized by 20Ne/22Ne ratios greater than 12.5, challenging the notion that the entire mantle acquired volatiles from solar wind implanted meteoritic materials. In this presentation we will explore alternative origins for these volatiles and provide testable predictions for each scenario. [1] G. Holland, C.J. Ballentine.. Nature 441 (2006), 186-191. [2] A. Gimberg et al. GCA 72 (2008), 626-645. [3] V.S. Heber et al. GCA 73 (2009), 7414-7432. [4] V. S. Heber et al. ApJ 759 (2012), 121. [5] R. Wieler in: D. Porcelli, C.J. Ballentine, R. Wieler (Eds.), Reviews in Mineralogy and Geochemistry 47 (2002), 21-70.

Plasma-tail activity at the time of the Vega encounters

NASA Technical Reports Server (NTRS)

Niedner, Malcolm B., Jr.; Schwingensuch, Konrad

1986-01-01

Physical associations are sought between Halley's plasma tail activity seen in ground-based imagery and near-comet, solar wind/IMF measurements obtained by the Vega spacecraft. Disconnection Events (DE's) and the sector boundary/frontside magnetic reconnection model (Niedner and Brandt, 1978) of their origin are discussed. Strong support for the model comes from 2 DE's: a major event whose onset, on March 7 to 8, is strongly correlated with a reversal of the comet's magnetic barrier observed by Vega-1 and Vega-2 and with an IMF sector boundary observed by Vega-1; and a minor event on March 7 which may be associated with the two-polarity (possibly reconnecting) magnetic barrier seen by Vega-1 on March 6, when the solar-wind density was low.

Winds and accretion in delta Sagittae

NASA Technical Reports Server (NTRS)

Eaton, Joel A.; Hartkopf, William I.; Mcalister, Harold A.; Mason, Brian D.

1995-01-01

The ten-year binary delta Sge (M2 Ib-II+B9.5 V) is a zeta Aur binary containing an abnormally cool component. Combining our analysis of the system as a visual binary with Batten's radial-velocity solution leads to the following properties: i = 40 deg, a = 51 mas = 8.83 A.U. = 1893 solar radius, hence d = 173 pc; M(sub B) = 2.9 solar mass and M(sub M) = 3.8 solar mass; and R(sub B) = 2.6 solar radius and R(sub M) = 152 solar radius. This interpretation of the orbit places the M supergiant on the asymptotic giant branch. We have collected ultraviolet spectra throughout the star's 1980-90 orbit, concentrated around the conjuction of 1990. The wind of the M giant appears in these as narrow shell lines of singly ionized metals, chiefly Fe II, with P-Cyg profiles at many phases, which show the slow variation in strength expected for the orbit but no pronounced atmospheric eclipse. The terminal velocity of the wind is 16-18 km/s, and its excitation temperature is approximately 10,000 K. Most of the broadening of the wind lines is caused by differential expansion of the atmosphere, with (unmeasurably) low turbulent velocities. Nontheless, the mass loss rate (1.1 +/- 0.4 X 10 (exp -8) solar mas/yr) is almost the same as found previously by Reimers and Schroder for very different assumptions about the velocity structure. Also seen in the spectrum throughout the orbit are the effects of a variable, high-speed wind as well as evidence for accretion onto the B9.5 star. This high-speed wind absorbs in species of all ionization stages observed, e. g., C II, Mg II, Al III, SI IV, C IV, and has a terminaal velocity in the range 200-450 km/s. We presume this wind originates at the B dwarf, not the M supergiant, and speculate that it comes from an accretion disk, as suggested by recent models of magnetically moderated accretion. Evidence for accretion is redshifted absorption in the same transitions formed in the high-speed wind, as well as broad emission lines of singly ionized metals. This emission seems to be scattered out of the continuum of the B star. Finally, we discuss Auger ionization by accretion luminosity as the cause of the high ionization in these high-speed flows as well as the source of the extended circumstellar clouds of Si(3+) and C(3+) ions in zeta Aur binaries.

Global solar magetic field organization in the extended corona: influence on the solar wind speed and density over the cycle.

NASA Astrophysics Data System (ADS)

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Lun C., E-mail: ltan@umd.edu

Since the field-line mixing model of Giacalone et al. suggests that ion dropouts cannot happen in the “gradual” solar energetic particle (SEP) event because of the large size of the particle source region in the event, the observational evidence of ion dropouts in the gradual SEP event should challenge the model. We have searched for the presence of ion dropouts in the gradual SEP event during solar cycle 23. From 10 SEP events the synchronized occurrence of ion and electron dropouts is identified in 12 periods. Our main observational facts, including the mean width of electron–ion dropout periods being consistentmore » with the solar wind correlation scale, during the dropout period the dominance of the slab turbulence component and the enhanced turbulence power parallel to the mean magnetic field, and the ion gyroradius dependence of the edge steepness in dropout periods, are all in support of the solar wind turbulence origin of dropout events. Also, our observation indicates that a wide longitude distribution of SEP events could be due to the increase of slab turbulence fraction with the increased longitude distance from the flare-associated active region.« less

Investigation of Solar Wind Correlations and Solar Wind Modifications Near Earth by Multi-Spacecraft Observations: IMP 8, WIND and INTERBALL-1

NASA Technical Reports Server (NTRS)

Paularena, Karolen I.; Richardson, John D.; Zastenker, Georgy N.

2002-01-01

The foundation of this Project is use of the opportunity available during the ISTP (International Solar-Terrestrial Physics) era to compare solar wind measurements obtained simultaneously by three spacecraft - IMP 8, WIND and INTERBALL-1 at wide-separated points. Using these data allows us to study three important topics: (1) the size and dynamics of near-Earth mid-scale (with dimension about 1-10 million km) and small-scale (with dimension about 10-100 thousand km) solar wind structures; (2) the reliability of the common assumption that solar wind conditions at the upstream Lagrangian (L1) point accurately predict the conditions affecting Earth's magnetosphere; (3) modification of the solar wind plasma and magnetic field in the regions near the Earth magnetosphere, the foreshock and the magnetosheath. Our Project was dedicated to these problems. Our research has made substantial contributions to the field and has lead others to undertake similar work.

Theoretical Technology Research for ISTP/SOLARMAX

NASA Technical Reports Server (NTRS)

Ashour-Abdalla, Maha; Acuna, Mario (Technical Monitor)

2000-01-01

During the last decade, we have been developing theoretical tools to support the scientific objectives of the International Solar Terrestrial Physics (ISTP) program. Results from our mission-oriented theory program have contributed significantly to the development of predictive capabilities by using real upstream solar wind conditions as input to our models and forecasting events observed downstream near Earth. We also developed the capability to unravel the complex information contained in ion velocity distribution functions measured near the Earth to determine their origin and energization process. During solar maximum, solar flares and coronal mass ejections (CMEs) dominate the sun's activity. It is now widely accepted that the impact of CMEs (or magnetic clouds) with the Earth's magnetosphere is the cause of most magnetic storms during solar maximum. One important aspect of a CME is the occurrence of solar energetic particle (SEP) events. During these events, protons, electrons, and heavy ions of solar origin are accelerated to very high energies by shock waves driven out from the sun. We carried out a series of large-scale kinetic (LSK) simulations to model the effect of SEPs on the near-Earth environment and the accessibility of these high-energy particles to the inner magnetosphere. We present the results of these studies.

Origin of the High-speed Jets Fom Magnetic Flux Emergence in the Solar Transition Region as well as Their Mass and Energy Contribuctions to the Solar Wind

NASA Astrophysics Data System (ADS)

Liping, Y.; He, J.; Peter, H.; Tu, C. Y.; Feng, X. S.

2015-12-01

In the solar atmosphere, the jets are ubiquitous and found to be at various spatia-temporal scales. They are significant to understand energy and mass transport in the solar atmosphere. Recently, the high-speed transition region jets are reported from the observation. Here we conduct a numerical simulation to investigate the mechanism in their formation, as well as their mass and energy contributions to the solar wind. Driven by the supergranular convection motion, the magnetic reconnection between the magnetic loop and the background open flux occurring in the transition region is simulated with a two-dimensional MHD model. The simulation results show that not only a fast hot jet, much resemble the found transition region jets, but also a adjacent slow cool jet, mostly like classical spicules, is launched. The force analysis shows that the fast hot jet is continually driven by the Lorentz force around the reconnection region, while the slow cool jet is induced by an initial kick through the Lorentz force associated with the emerging magnetic flux. Also, the features of the driven jets change with the amount of the emerging magnetic flux, giving the varieties of both jets.With the developed one-dimensional hydrodynamic solar wind model, the time-dependent pulses are imposed at the bottom to simulate the jet behaviors. The simulation results show that without other energy source, the injected plasmas are accelerated effectively to be a transonic wind with a substantial mass flux. The rapid acceleration occurs close to the Sun, and the resulting asymptotic speeds, number density at 0.3 AU, as well as mass flux normalized to 1 AU are compatible with in site observations. As a result of the high speed, the imposed pulses lead to a train of shocks traveling upward. By tracing the motions of the injected plasma, it is found that these shocks heat and accelerate the injected plasma to make part of them propagate upward and eventually escape. The parametric study shows that as the speed and temperature of the imposed pulses increase, we get an increase of the speed and temperature of the driven solar wind, which do not be influenced by the increase of the number density of the imposed pulses. When the recurring period of the imposed pulses decreases, the obtained solar wind becomes slower and cooler.

A Proton-Cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar Wind

NASA Technical Reports Server (NTRS)

Wicks, R. T.; Alexander, R. L.; Stevens, M.; Wilson, L. B., III; Moya, P. S.; Vinas, A.; Jian, L. K.; Roberts, D. A.; O’Modhrain, S.; Gilbert, J. A.;

The Abundance of Helium in the Source Plasma of Solar Energetic Particles

NASA Astrophysics Data System (ADS)

Reames, Donald V.

2017-11-01

Studies of patterns of abundance enhancements of elements, relative to solar coronal abundances, in large solar energetic-particle (SEP) events, and of their power-law dependence on the mass-to-charge ratio, A/Q, of the ions, have been used to determine the effective source-plasma temperature, T, that defines the Q-values of the ions. We find that a single assumed value for the coronal reference He/O ratio in all SEP events is often inconsistent with the transport-induced power-law trend of the other elements. In fact, the coronal He/O varies rather widely from one SEP event to another. In the large Fe-rich SEP events with T ≈ 3 MK, where shock waves, driven out by coronal mass ejections (CMEs), have reaccelerated residual ions from impulsive suprathermal events that occur earlier in solar active regions, He/O ≈ 90, a ratio similar to that in the slow solar wind, which may also originate from active regions. Ions in the large SEP events with T < 2 MK may be accelerated outside active regions, and have values of 40 ≤ He/O ≤ 60. Mechanisms that determine coronal abundances, including variations of He/O, are likely to occur near the base of the corona (at ≈ 1.1 RS) and thus to affect both SEPs (at 2 - 3 RS) and the solar wind. Other than He, reference coronal abundances for heavier elements show little temperature dependence or systematic difference between SEP events; He, the element with the highest first-ionization potential, is unique. The CME-driven shock waves probe the same regions of space, at ≈ 2 RS near active regions, which are also likely sources of the slow solar wind, providing complementary information on conditions in those regions.

Data-driven Modeling of the Solar Corona by a New Three-dimensional Path-conservative Osher-Solomon MHD Model

NASA Astrophysics Data System (ADS)

Feng, Xueshang; Li, Caixia; Xiang, Changqing; Zhang, Man; Li, HuiChao; Wei, Fengsi

2017-11-01

A second-order path-conservative scheme with a Godunov-type finite-volume method has been implemented to advance the equations of single-fluid solar wind plasma magnetohydrodynamics (MHD) in time. This code operates on the six-component composite grid system in three-dimensional spherical coordinates with hexahedral cells of quadrilateral frustum type. The generalized Osher-Solomon Riemann solver is employed based on a numerical integration of the path-dependent dissipation matrix. For simplicity, the straight line segment path is used, and the path integral is evaluated in a fully numerical way by a high-order numerical Gauss-Legendre quadrature. Besides its very close similarity to Godunov type, the resulting scheme retains the attractive features of the original solver: it is nonlinear, free of entropy-fix, differentiable, and complete, in that each characteristic field results in a different numerical viscosity, due to the full use of the MHD eigenstructure. By using a minmod limiter for spatial oscillation control, the path-conservative scheme is realized for the generalized Lagrange multiplier and the extended generalized Lagrange multiplier formulation of solar wind MHD systems. This new model that is second order in space and time is written in the FORTRAN language with Message Passing Interface parallelization and validated in modeling the time-dependent large-scale structure of the solar corona, driven continuously by Global Oscillation Network Group data. To demonstrate the suitability of our code for the simulation of solar wind, we present selected results from 2009 October 9 to 2009 December 29 show its capability of producing a structured solar corona in agreement with solar coronal observations.

Solar wind influence on Jupiter's magnetosphere and aurora

NASA Astrophysics Data System (ADS)

Vogt, Marissa; Gyalay, Szilard; Withers, Paul

2016-04-01

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

Comparison of the Effects of Wave-Particle Interactions and the Kinetic Suprathermal Electron Population on the Acceleration of the Solar Wind

NASA Technical Reports Server (NTRS)

Tam, S. W. Y.; Chang, T.

2002-01-01

Kinetic effects due to wave-particle interactions and suprathermal electrons have been suggested in the literature as possible solar wind acceleration mechanisms. Ion cyclotron resonant heating, in particular, has been associated with some qualitative features observed in the solar wind. In terms of solar wind acceleration, however, it is interesting to compare the kinetic effects of suprathermal electrons with those due to the wave-particle interactions. The combined effects of the two acceleration mechanisms on the fast solar wind have been studied by Tam and Chang (1999a,b). In this study. we investigate the role of the suprathermal electron population in the acceleration of the solar wind. Our model follows the global kinetic evolution of the fast solar wind under the influence of ion cyclotron resonant heating, while taking into account Coulomb collisions, and the ambipolar electric field that is consistent with the particle distributions themselves. The kinetic effects due to the suprathermal electrons, which we define to be the tail of the electron distributions, can be included in the model as an option. By comparing the results with and without the inclusion of the suprathermal electron effects, we determine the relative importance of suprathermal electrons and wave-particle interactions in driving the solar wind. We find that although suprathermal electrons enhance the ambipolar electric potential in the solar wind considerably, their overall influence as an acceleration mechanism is relatively insignificant in a wave-driven solar wind.

Exploration of Solar Wind Acceleration Region Using Interplanetary Scintillation of Water Vapor Maser Source and Quasars

NASA Technical Reports Server (NTRS)

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.

Exploration of Solar Wind Acceleration Region Using Interplanetary Scintillation of Water Vapor Maser Source and Quasars

NASA Technical Reports Server (NTRS)

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.

The solar wind neon abundance observed with ACE/SWICS and ULYSSES/SWICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Space-based measurements of elemental abundances and their relation to solar abundances

NASA Technical Reports Server (NTRS)

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

1990-01-01

The Ion Composition Instrument (ICI) aboard the ISEE-3/ICE spacecraft was in the solar wind continuously from August 1978 to December 1982. The results made it possible to establish long-term average solar wind abundance values for helium, oxygen, neon, silicon, and iron. The Charge-Energy-Mass instrument aboard the CCE spacecraft of the AMPTE mission has measured the abundance of these elements in the magnetosheath and has also added carbon, nitrogen, magnesium, and sulfur to the list. There is strong evidence that these magnetosheath abundances are representative of the solar wind. Other sources of solar wind abundances are Solar Energetic Particle experiments and Apollo lunar foils. When comparing the abundances from all of these sources with photospheric abundances, it is clear that helium is depleted in the solar wind while silicon and iron are enhanced. Solar wind abundances for carbon, nitrogen, oxygen, and neon correlate well with the photospheric values. The incorporation of minor ions into the solar wind appears to depend upon both the ionization times for the elements and the Coulomb drag exerted by the outflowing proton flux.

The structure of the inner heliosphere from Pioneer Venus and IMP observations

NASA Technical Reports Server (NTRS)

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

1992-01-01

The IMP 8 and Pioneer Venus Orbiter (PVO) spacecraft explore the region of heliographic latitudes between 8 deg N and 8 deg S. Solar wind observations from these spacecraft are used to construct synoptic maps of solar wind parameters in this region. These maps provide an explicit picture of the structure of high speed streams near 1 AU and how that structure varies with time. From 1982 until early 1985, solar wind parameters varied little with latitude. During the last solar minimum, the solar wind developed strong latitudinal structure; high speed streams were excluded from the vicinity of the solar equator. Synoptic maps of solar wind speed are compared with maps of the coronal source surface magnetic field. This comparison reveals the expected correlation between solar wind speed near 1 AU, the strength of the coronal magnetic field, and distance from the coronal neutral line.

Elemental abundances in corotating events

NASA Technical Reports Server (NTRS)

Vonrosenvinge, T. T.; Mcguire, R. E.

1985-01-01

Large, persistent solar-wind streams in 1973 and 1974 produced corotating interaction regions which accelerated particles to energies of a few MeV/nucleon. The proton to helium ratio (H/He) was remarkably constant at a value (22 + or 5) equal to that in the solar wind (21 + or - 3), suggesting that particles were being accelerated directly out of the solar wind. Preliminary results were presented from a similar study approximately 11 years (i.e., one solar cycle) later. Corotating events have been identified by surveying the solar wind data, energetic particle time-histories and anisotropies. This data was all obtained from the ISEE-3/ICE spacecraft. These events also show H/He ratios similar to that in the solar wind. It is flund that in these cases there is evidence for H/He ratios which are significantly different from that of the solar wind but which are consistent with the range of values found in solar flare events.

SELMA mission: revealing the origin of lunar water

NASA Astrophysics Data System (ADS)

Barabash, Stas; Selma Team

2013-04-01

We propose a very low cost lunar mission to cover a poorly investigated inter-disciplinary area in the lunar science. The mission SELMA (Surface, Environment, and Lunar Magnetic Anomalies) investigates the interaction of the neutral and plasma environment with the lunar surface and the impact of this interaction on the surface composition, in the first hand, on the presence of water. The mission focuses on the fundamental question: What is the origin of the water in the lunar soil? The mission also addresses the questions: What are the lunar exosphere content and composition and how does the exosphere interact with the surface? How do the lunar magnetic anomalies interact with the solar wind and affect the surface? SELMA investigates the origin of the water in the lunar soil via simultaneous measurements of the OH/H2O abundance in the soil, the proton flux deposited to the surface, and transient changes in the exospheric gas content and composition. The water content in the surface is mapped via measurements of the 2700 - 3300 nm OH/H2O/ice absorption lines. The proton flux at the surface is measured remotely via backscattered hydrogen flux (energetic neutral atoms, ENAs). The exospheric gas content and composition and possible transient changes due to micrometeoroid influx or outgassing are monitored by a neutral gas mass spectrometer. Little is known about the tenuous lunar exosphere, its composition, structure, and relation to the plasma environment. The reasons for the present poor knowledge of the lunar exosphere is the difficulty of observations due to the low number densities, and the complexity of models due to the multiplicity of the mechanisms responsible for the input and loss of exospheric species. To investigate the lunar exosphere SELMA is equipped with state-of-the-art time-of-flight neutral gas mass spectrometer with unprecedented sensitivity and mass resolution. The Moon does not have a global magnetic field but possesses local magnetizations. The magnetizations interact with the solar wind plasma creating highly variable mini-magnetospheres affecting, through an as yet unknown mechanism, the surface visible albedo. The electrodynamical interaction is very complex being one of the fundamental solar wind interactions in the solar system. SELMA studies how the magnetic anomaly interact with the solar wind and surface via simultaneous measurements of 3D ion and electron distribution functions, the local magnetic field, solar wind flux variations on the surface through ENA imaging of the backscattered hydrogen flux, imaging in the visible range, and measuring the surface IR spectrum. The SELMA results will be of critical importance for the interpretation of data from Mercury to be collected by the ESA BepiColombo mission in 2020 - 2022. To address its scientific objectives SELMA carries a highly focused suite of instruments including an IR spectrometer, an ENA telescope, an ion and electron spectrometer, a neutral gas mass spectrometer, a magnetometer, and a visible camera. SELMA is a spinning platform to be inserted on a low maintenance quasi-frozen polar orbit of 30 km x 216 km by a dedicated launch and a solid state fuel kick stage. SELMA was proposed to ESA as a candidate for the S-class mission.

Latitudinal variation of speed and mass flux in the acceleration region of the solar wind inferred from spectral broadening measurements

NASA Technical Reports Server (NTRS)

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.

Solar wind and the motion of dust grains

NASA Astrophysics Data System (ADS)

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.

Statistical validation of a solar wind propagation model from 1 to 10 AU

NASA Astrophysics Data System (ADS)

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.

Solar wind and magnetosphere interactions

NASA Technical Reports Server (NTRS)

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

1979-01-01

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

Position of the IBEX ribbon as a key to understand its origin

NASA Astrophysics Data System (ADS)

Swaczyna, Pawel; Bzowski, Maciej; Sokół, Justyna M.; Christian, Eric R.; Funsten, Herbert O.; McComas, David J.; Schwadron, Nathan A.

2017-04-01

Observations of the energetic neutral atom (ENA) emission by the Interstellar Boundary Explorer (IBEX) allow for remote sensing of the plasma properties in heliosheath. The first IBEX results revealed an unexpected arc-like enhancement of the ENA flux in the sky, dubbed the IBEX ribbon. This discovery led to formulation of more than a dozen hypotheses on its origin. The emission source region proposed in these hypotheses span the heliospheric termination shock up to a hypothetical nearby interface between the Local Interstellar Cloud and a local bay in the Local Bubble. Among these hypotheses is the concept that the ribbon is produced by the secondary ENA mechanism, operating in the outer heliosheath. The observational strategy of IBEX allows observation of the same part of the sky from the opposite sides of the Sun every six months and thus provides parallax viewing with a baseline of 2 AU. After correcting the observations for the Compton-Getting effect and for gravitational deflection and radiation pressure, we use this parallax viewing to precisely determine the apparent position of the maximum flux associated with the ribbon. We find that the ribbon peak position differs semi-annually by an angle of 0.41±0.15 deg, which we interpret as the parallax effect. This angle corresponds to a distance of 140-38+84 AU, and thus suggests that most likely the ribbon's source is located just beyond the heliopause. Comparison of the IBEX ribbon position in five energy steps of IBEX-Hi shows a systematic shift, which changes the position of the ribbon center by ˜10 deg. We find that it can be explained using an analytic model of the secondary ENA mechanism with the neutralized supersonic solar wind as the source of the primary ENAs, which are ionized in the outer heliosheath, picked up by the ambient magnetic field, and eventually re-neutralized (as originally conceived, McComas et al. 2009). We use a realistic model of the solar wind evolution dependent on heliographic latitude, calculated the neutral solar wind flux and averaged it over the solar cycle, which was then used as the input in the analytic model of the secondary ENAs. The modeled ENA emission signal as observed at IBEX reproduces the observed features of the IBEX ribbon: the relative signal intensity along the ribbon in each energy channel and the shift of the ribbon center. The combination of the distance to the ribbon source obtained from parallax and the energy progression of the ribbon center location suggest that the secondary ENA mechanism is a plausible explanation for the ribbon origin. A better resolution of the ENA detectors expected on the IMAP mission will enable a more accurate determination of the ribbon's position and will extend observations to higher energies. In consequence, a better determination of its parallax should be possible, and time-dependent effects resulting from the evolution of the supersonic solar wind structure with time will provide additional, critical signatures of the ribbon origin.

MHD Simulation for Investigating the Dynamic State Transition Responsible for a Solar Eruption in Active Region 12158

NASA Astrophysics Data System (ADS)

Lee, Hwanhee; Magara, Tetsuya

2018-06-01

We present a magnetohydrodynamic model of solar eruption based on the dynamic state transition from the quasi-static state to the eruptive state of an active region (AR) magnetic field. For the quasi-static state before an eruption, we consider the existence of a slow solar wind originating from an AR, which may continuously make the AR magnetic field deviate from mechanical equilibrium. In this model, we perform a three-dimensional magnetohydrodynamic simulation of AR 12158 producing a coronal mass ejection, where the initial magnetic structure of the simulation is given by a nonlinear force-free field derived from an observed photospheric vector magnetic field. We then apply a pressure-driven outflow to the upper part of the magnetic structure to achieve a quasi-static pre-eruptive state. The simulation shows that the eruptive process observed in this AR may be caused by the dynamic state transition of an AR magnetic field, which is essentially different from the destabilization of a static magnetic field. The dynamic state transition is determined from the shape evolution of the magnetic field line according to the κH-mechanism. This work demonstrates how the mechanism works to produce a solar eruption in the dynamic solar corona governed by the gravitational field and the continuous outflows of solar wind.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, S. Y.; Yuan, Z. G.; Hadid, L. Z.

In the solar wind, power spectral density (PSD) of the magnetic field fluctuations generally follow the so-called Kolmogorov spectrum f {sup −5/3} in the inertial range, where the dynamics is thought to be dominated by nonlinear interactions between counter-propagating incompressible Alfvén wave parquets. These features are thought to be ubiquitous in space plasmas. The present study gives a new and more complex picture of magnetohydrodynamic (MHD) turbulence as observed in the terrestrial magnetosheath. The study uses three years of in situ data from the Cluster mission to explore the nature of the magnetic fluctuations at MHD scales in different locationsmore » within the magnetosheath, including flanks and subsolar regions. It is found that the magnetic field fluctuations at MHD scales generally have a PSD close to f {sup −1} (shallower than the Kolmogorov one f {sup −5/3}) down to the ion characteristic scale, which recalls the energy-containing scales of solar wind turbulence. The Kolmogorov spectrum is observed only away from the bow shock toward the flank and the magnetopause regions in 17% of the analyzed time intervals. Measuring the magnetic compressibility, it is shown that only a fraction (35%) of the observed Kolmogorov spectra was populated by shear Alfvénic fluctuations, whereas the majority of the events (65%) was found to be dominated by compressible magnetosonic-like fluctuations, which contrasts with well-known turbulence properties in the solar wind. This study gives a first comprehensive view of the origin of the f {sup −1} and the transition to the Kolmogorov inertial range; both questions remain controversial in solar wind turbulence.« less

Space Weathering Radiation Environment of the Inner Solar System from the Virtual Energetic Particle Observatory

NASA Astrophysics Data System (ADS)

Cooper, J. F.; Papitashvili, N. E.

2016-12-01

The surfaces of Mercury, the Moon, the moons of Mars, the asteroids, and other small bodies of the inner solar system have been directly weathered for millions to billions of years by solar wind, energetic particle, and solar ultraviolet irradiation. Surface regolith layers to meters in depth are formed by impacts of smaller bodies and micrometeoroids. Sample return missions to small bodies, such as Osiris-REx to the asteroid Bennu, are intended to recover information on the early history of solar system formation, but must contend with the long-term space weathering effects that perturb the original structure and composition of the affected bodies. Solar wind plasma ions at keV energies penetrate only to sub-micron depths, while more energetic solar & heliospheric particles up to MeV energies reach centimeter depths, and higher-energy galactic cosmic rays to GeV energies fully penetrate through the impact regolith. The weathering effects vary with energy and penetration depth from ion implantation and erosive sputtering at solar wind energies to chemical and structural evolution driven by MeV - GeV particles. The energy versus depth dependence of such effects is weighted by the differential flux distributions of the incident particles as measured near the orbits of the affected bodies over long periods of time. Our Virtual Energetic Particle Observatory (http://vepo.gsfc.nasa.gov/) enables simultaneous access to multiple data sets from 1973 through the present in the form of differential flux spectral plots and downloadable data tables. The most continuous VEPO coverage exists for geospace data sources at 1 AU from the Interplanetary Monitoring Platform 8 (IMP-8), launched in 1973, through the present 1-AU constellation including the ACE, WIND, SOHO, and Stereo-A/B spacecraft. Other mission data, e.g. more occasionally from Pioneer-10/11, Helios-1/2, Voyager-1/2, and Ulysses, extend heliospheric coverage from the orbit of Mercury to that of Mars, the asteroid belt, and beyond. Using data from the VEPO services, we show the time-averaged spectra of protons and helium during 1973 - 2016 from Mercury to Mars. The main contributors on solar cycle time scales at keV to MeV energies are large solar flare and ICME events. These time-averaged spectra can then be used for space weathering models of the inner solar system.

Turbulent Transport in a Three-dimensional Solar Wind

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Deflection and Distortion of CME internal magnetic flux rope due to the interaction with a structured solar wind

NASA Astrophysics Data System (ADS)

Shiota, D.; Iju, T.; Hayashi, K.; Fujiki, K.; Tokumaru, M.; Kusano, K.

2016-12-01

CMEs are the most violent driver of geospace disturbances, and therefore their arrival to the Earth position is an important factor in space weather forecast. The dynamics of CME propagation is strongly affected by the interaction with background solar wind. To understand the interaction between a CME and background solar wind, we performed three-dimensional MHD simulations of the propagation of a CME with internal twisted magnetic flux rope into a structured bimodal solar wind. We compared three different cases in which an identical CME is launched into an identical bimodal solar wind but the launch dates of the CME are different. Each position relative to the boundary between slow and fast solar winds becomes almost in the slow wind stream region, almost in the fast wind stream region, or in vicinity of the boundary of the fast and slow solar wind stream (that grows to CIR). It is found that the CME is most distorted and deflected eastward in the case near the CIR, in contrast to the other two cases. The maximum strength of southward magnetic field at the Earth position is also highest in the case near CIR. The results are interpreted that the dynamic pressure gradient due to the back reaction from pushing the ahead slow wind stream and due to the collision behind fast wind stream hinders the expansion of the CME internal flux rope into the direction of the solar wind velocity gradient. As a result, the expansion into the direction to the velocity gradient is slightly enhanced and results in the enhanced deflection and distortion of the CME and its internal flux rope. These results support the pileup accident hypothesis proposed by Kataoka et al. (2015) to form unexpectedly geoeffective solar wind structure.

Mapping the Solar Wind from its Source Region into the Outer Corona

NASA Technical Reports Server (NTRS)

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.

Microphysics of Waves and Instabilities in the Solar Wind and their Macro Manifestations in the Corona and Interplanetary Space

NASA Technical Reports Server (NTRS)

Gurman, Joseph (Technical Monitor); Habbal, Shadia Rifai

2004-01-01

Investigations of the physical processes responsible for coronal heating and the acceleration of the solar wind were pursued with the use of our recently developed 2D MHD solar wind code and our 1D multifluid code. In particular, we explored (1) the role of proton temperature anisotropy in the expansion of the solar wind, (2) the role of plasma parameters at the coronal base in the formation of high speed solar wind streams at mid-latitudes, and (3) the heating of coronal loops.

Comparative study of energetic heliospheric electrons at wind and geotail

NASA Technical Reports Server (NTRS)

Chaizy, P. A.; Lanzerotti, L. J.; Lin, R. P.; Lepping, R. P.; Kokubun, S. K.; Bosqued, J.-M.; Sanderson, T. R.; Yamamoto, T.

1997-01-01

The current fleet of both heliospheric and magnetospheric spacecraft provides a unique opportunity of studying spatio-temporal plasma phenomena. Among the numerous topics that can be addressed by such a fleet, figures the 3D study of energetic (greater than 20 keV) solar electron) solar electron events. WIND and GEOTAIL are particulary interesting for such analysis: more than two years of data; up to 3/4 continuous days spent by GEOTAIL in the solar wind; and comparable experiments. During solar electron events, rapid electron flux changes can be associated with these structures. Sometimes they are seen at both spacecraft with a time difference corresponding to the convection time, but sometimes they are observed at one spacecraft but not at the other. Several preliminary conclusions can be drawn from such events: (1) there is direct evidence that, within distances lower than 1.5 x 10(exp 6) km at 1 A (approximately 7000 km at the sun), there are significant spatial variations of (a) the magnetic field line connections to the source region and probably of (b) the particle propagation features; (2) magnetic field lines inside and outside particle propagation structures can keep distinct access to the source region for more than one hour; (3) flux waves, of probable local origin, were observed; and (4) within one hour, spatial flux discrepancies, separated by magnetic structures, may remain or disappear.

Quasilinear saturation of the aperiodic ordinary mode streaming instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stockem Novo, A., E-mail: anne@tp4.rub.de; Schlickeiser, R.; Yoon, P. H.

2015-09-15

In collisionless plasmas, only kinetic instabilities and fluctuations are effective in reducing the free energy and scatter plasma particles, preventing an increase of their anisotropy. Solar energetic outflows into the interplanetary plasma give rise to important thermal anisotropies and counterstreaming motions of plasma shells, and the resulting instabilities are expected to regulate the expansion of the solar wind. The present paper combines quasilinear theory and kinetic particle-in-cell simulations in order to study the weakly nonlinear saturation of the ordinary mode in hot counter-streaming plasmas with a temperature anisotropy as a follow-up of the paper by Seough et al. [Phys. Plasmasmore » 22, 082122 (2015)]. This instability provides a plausible mechanism for the origin of dominating, two-dimensional spectrum of transverse magnetic fluctuations observed in the solar wind. Stimulated by the differential motion of electron counterstreams the O mode instability may convert their free large-scale energy by nonlinear collisionless dissipation on plasma particles.« less

Thermal structure and heat balance of the outer planets

NASA Technical Reports Server (NTRS)

Conrath, B. J.; Hanel, R. A.; Samuelson, R. E.

1989-01-01

Current knowledge of the thermal structure and energy balance of the outer planets is summarized. The Voyager spacecraft experiments have provided extensive new information on the atmospheric temperatures and energetics of Jupiter, Saturn and Uranus. All three planets show remarkably small global-scale horizontal thermal contrast, indicating efficient redistribution of heat within the atmospheres or interiors. Horizontal temperature gradients on the scale of the zonal jets indicate that the winds decay with height in the upper troposphere. This suggests that the winds are driven at deeper levels and are subjected to frictional damping of unknown origin at higher levels. Both Jupiter and Saturn have internal power sources equal to about 70 percent of the absorbed solar power. This result is consistent with the view that significant helium differentiation has occurred on Saturn. Uranus has an internal power no greater than 13 percent of the absorbed solar power, while earth-based observations suggest Neptune has an internal power in excess of 100 percent of the absorbed solar power.

Three-dimensional exploration of the solar wind using observations of interplanetary scintillation

PubMed Central

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

Inter-Agency Consultative Group for Space Science (IACG): Handbook of Missions and Payloads

NASA Technical Reports Server (NTRS)

1994-01-01

The ACE spacecraft design is based on the Charge Composition Explorer (CCE) built by Johns Hopkins University (JHU) and the Applied Physics Lab (APL) for the AMPTE program. ACE is designed as a spinning spacecraft with its spin axis aligned to the Earth-Sun axis. The ACE launch weight will be approx. 633 kg, including 105 kg of scientific instruments and 184 kg of propellant. Using a Delta-class expendable launch vehicle, ACE will be launched into an L1 libration point (240 R(sub e)) orbit. Telemetry will be 6.7 kbps average, using tape recorder storage with daily readout to DSN. The experiment power requirement is approximately 76 W nominal and 96 W peak. The prime objective of the ACE mission is: (1) to determine accurate elemental and isotropic abundances including solar matter, local interstellar matter and local galactic matter; (2) to study the origin of elements and evolutionary processing in galactic nucleosynthesis, galactic evolution, origin and evolution of the solar system; (3) to study coronal formation and solar-wind acceleration processes; and (4) to study particle acceleration and transport, including coronal shock acceleration, stochastic flare acceleration, interplanetary shock acceleration, and interstellar acceleration and propagation. To accomplish this objective, ACE will perform comprehensive and coordinated determinations of the elemental and isotopic composition of energetic nuclei accelerated on the Sun, in interplanetary space, and from galactic sources. These observations will span five decades in energy, from solar wind to galactic cosmic ray energies, and will cover the element range from H-1 to Zr-40. Comparison of these samples of matter will be used to study the origin and subsequent evolution of both solar system and galactic material by isolating the effects of fundamental processes that include nucleosynthesis, charged and neutral particle separation, bulk plasma acceleration, and the acceleration of suprathermal and high-energy particles.

Little or no solar wind enters Venus' atmosphere at solar minimum.

PubMed

Zhang, T L; Delva, M; Baumjohann, W; Auster, H-U; Carr, C; Russell, C T; Barabash, S; Balikhin, M; Kudela, K; Berghofer, G; Biernat, H K; Lammer, H; Lichtenegger, H; Magnes, W; Nakamura, R; Schwingenschuh, K; Volwerk, M; Vörös, Z; Zambelli, W; Fornacon, K-H; Glassmeier, K-H; Richter, I; Balogh, A; Schwarzl, H; Pope, S A; Shi, J K; Wang, C; Motschmann, U; Lebreton, J-P

2007-11-29

Venus has no significant internal magnetic field, which allows the solar wind to interact directly with its atmosphere. A field is induced in this interaction, which partially shields the atmosphere, but we have no knowledge of how effective that shield is at solar minimum. (Our current knowledge of the solar wind interaction with Venus is derived from measurements at solar maximum.) The bow shock is close to the planet, meaning that it is possible that some solar wind could be absorbed by the atmosphere and contribute to the evolution of the atmosphere. Here we report magnetic field measurements from the Venus Express spacecraft in the plasma environment surrounding Venus. The bow shock under low solar activity conditions seems to be in the position that would be expected from a complete deflection by a magnetized ionosphere. Therefore little solar wind enters the Venus ionosphere even at solar minimum.

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.

Studying Solar Wind Properties Around CIRs and Their Effects on GCR Modulation

NASA Astrophysics Data System (ADS)

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.

RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Imaging the Top of the Solar Corona and the Young Solar Wind

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Were chondrites magnetized by the early solar wind?

NASA Astrophysics Data System (ADS)

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.

TURBULENCE IN THE SOLAR WIND MEASURED WITH COMET TAIL TEST PARTICLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

ULF Wave Activity in the Magnetosphere: Resolving Solar Wind Interdependencies to Identify Driving Mechanisms

NASA Astrophysics Data System (ADS)

Bentley, S. N.; Watt, C. E. J.; Owens, M. J.; Rae, I. J.

2018-04-01

Ultralow frequency (ULF) waves in the magnetosphere are involved in the energization and transport of radiation belt particles and are strongly driven by the external solar wind. However, the interdependency of solar wind parameters and the variety of solar wind-magnetosphere coupling processes make it difficult to distinguish the effect of individual processes and to predict magnetospheric wave power using solar wind properties. We examine 15 years of dayside ground-based measurements at a single representative frequency (2.5 mHz) and a single magnetic latitude (corresponding to L ˜ 6.6RE). We determine the relative contribution to ULF wave power from instantaneous nonderived solar wind parameters, accounting for their interdependencies. The most influential parameters for ground-based ULF wave power are solar wind speed vsw, southward interplanetary magnetic field component Bz<0, and summed power in number density perturbations δNp. Together, the subordinate parameters Bz and δNp still account for significant amounts of power. We suggest that these three parameters correspond to driving by the Kelvin-Helmholtz instability, formation, and/or propagation of flux transfer events and density perturbations from solar wind structures sweeping past the Earth. We anticipate that this new parameter reduction will aid comparisons of ULF generation mechanisms between magnetospheric sectors and will enable more sophisticated empirical models predicting magnetospheric ULF power using external solar wind driving parameters.

Integrating Wind and Solar on the Grid-NREL Analysis Leads the Way -

Science.gov Websites

shown in color, but not including pink/IESO area.) Map provided by NREL Integrating Wind and Solar on the Grid-NREL Analysis Leads the Way NREL studies confirm big wind, solar potential for grid integration To fully harvest the nation's bountiful wind and solar resources, it is critical to know how much

Global Network of Slow Solar Wind

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

Hawaii Solar and Wind Integration Studies | Grid Modernization | NREL

Science.gov Websites

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

The average solar wind in the inner heliosphere: Structures and slow variations

NASA Technical Reports Server (NTRS)

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.

The magnetospheric electric field and convective processes as diagnostics of the IMF and solar wind

NASA Technical Reports Server (NTRS)

Kaye, S. M.

1979-01-01

Indirect measurements of the convection field as well as direct of the ionospheric electric field provide a means to at least monitor quanitatively solar wind processes. For instance, asymmetries in the ionospheric electric field and ionospheric Hall currents over the polar cap reflect the solar wind sector polarity. A stronger electric field, and thus convective flow, is found on the side of the polar cap where the y component of the IMF is parallel to the y component of the geomagnetic field. Additionally, the magnitude of the electric field and convective southward B sub Z and/or solar wind velocity, and thus may indicate the arrival at Earth of an interaction region in the solar wind. It is apparent that processes associated with the convention electric field may be used to predict large scale features in the solar wind; however, with present empirical knowledge it is not possible to make quantitative predictions of individual solar wind or IMF parameters.

Statistical Methods for Quantifying the Variability of Solar Wind Transients of All Sizes

NASA Astrophysics Data System (ADS)

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: 10.1002/2016GL068920.

Substorm occurrence rates, substorm recurrence times, and solar wind structure

NASA Astrophysics Data System (ADS)

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.

Quasi-biennial oscillations in the geomagnetic field: Their global characteristics and origin

NASA Astrophysics Data System (ADS)

Ou, Jiaming; Du, Aimin; Finlay, Christopher C.

2017-05-01

Quasi-biennial oscillations (QBOs), with periods in the range 1-3 years, have been persistently observed in the geomagnetic field. They provide unique information on the mechanisms by which magnetospheric and ionospheric current systems are modulated on interannual timescales and are also of crucial importance in studies of rapid core field variations. In this paper, we document the global characteristics of the geomagnetic QBO, using ground-based data collected by geomagnetic observatories between 1985 and 2010, and reexamine the origin of the signals. Fast Fourier transform analysis of second-order derivatives of the geomagnetic X, Y, and Z components reveals salient QBO signals at periods of 1.3, 1.7, 2.2, 2.9, and 5.0 years, with the most prominent peak at 2.2 years. The signature of geomagnetic QBO is generally stronger in the X and Z components and with larger amplitudes on geomagnetically disturbed days. The amplitude of the QBO in the X component decreases from the equator to the poles, then shows a local maximum at subauroral and auroral zones. The QBO in the Z component enhances from low latitudes toward the polar regions. At high latitudes (poleward of 50°) the geomagnetic QBO exhibits stronger amplitudes during LT 00:00-06:00, depending strongly on the geomagnetic activity level, while at low latitudes the main effect is in the afternoon sector. These results indicate that the QBOs at low-to-middle latitudes and at high latitudes are influenced by different magnetospheric and ionospheric current systems. The characteristics of the multiple peaks in the QBO range are found to display similar latitudinal and local time distributions, suggesting that these oscillations are derived from a common source. The features, including the strong amplitudes seen on disturbed days and during postmidnight sectors, and the results from spherical harmonic analysis, verify that the majority of geomagnetic QBO is of external origin. We furthermore find a very high correlation between the geomagnetic QBO and the QBOs in solar wind speed and solar wind dynamic pressure. This suggests the geomagnetic QBO primarily originates from the current systems due to the solar wind-magnetosphere-ionosphere coupling process.

Solar Probe Plus: Report of the Science and Technology Definition Team

NASA Technical Reports Server (NTRS)

2008-01-01

Solar Probe+ will be an extraordinary and historic mission, exploring what is arguably the last region of the solar system to be visited by a spacecraft, the Sun s outer atmosphere or corona as it extends out into space. Approaching as close as 9.5 RS* (8.5 RS above the Sun s surface), Solar Probe+ will repeatedly sample the near-Sun environment, revolutionizing our knowledge and understanding of coronal heating and of the origin and evolution of the solar wind and answering critical questions in heliophysics that have been ranked as top priorities for decades. Moreover, by making direct, in-situ measurements of the region where some of the most hazardous solar energetic particles are energized, Solar Probe+ will make a fundamental contribution to our ability to characterize and forecast the radiation environment in which future space explorers will work and live.

Termination of the solar wind in the hot, partially ionized interstellar medium. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

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.

A Deeper Understanding of Stability in the Solar Wind: Applying Nyquist's Instability Criterion to Wind Faraday Cup Data

NASA Astrophysics Data System (ADS)

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.

Solar wind control of auroral zone geomagnetic activity

NASA Technical Reports Server (NTRS)

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

1981-01-01

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

Conversion of magnetic field energy into kinetic energy in the solar wind

NASA Technical Reports Server (NTRS)

Whang, Y. C.

1972-01-01

The outflow of the solar magnetic field energy (the radial component of the Poynting vector) per steradian is inversely proportional to the solar wind velocity. It is a decreasing function of the heliocentric distance. When the magnetic field effect is included in the one-fluid model of the solar wind, the transformation of magnetic field energy into kinetic energy during the expansion process increases the solar wind velocity at 1 AU by 17 percent.

The solar wind in the third dimension

NASA Technical Reports Server (NTRS)

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.

Potential for a Danish power system using wind energy generators, solar cells and storage

NASA Astrophysics Data System (ADS)

Blegaa, S.; Christiansen, G.

1981-10-01

Performance characteristics of a combined solar/wind power system equipped with storage and an unspecified back-up power source are studied on the basis of meteorological data in Denmark from 1959-1972. A model for annual production and storage from wind/solar installations is presented, assuming 12% efficiency for the solar cells and various power coefficients of the windmills, in addition to long and short-term storage. Noting that no correlation between wind and solar energy availability was found, and a constant ratio of 60% wind/40% solar was determined to be the optimum mix for large scale power production without taking into consideration the variations among years. It is concluded that 80-90% of the total Danish electrical load can be covered by solar/wind systems, and 100% may be possible with the addition of pumped hydroelectric storage.

Remote Sensing of the Solar Wind Density, Speed, and Temperature in the Region between the Sun and Parker Solar Probe

NASA Astrophysics Data System (ADS)

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.

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

Missing pressure in the dayside ionosphere of Venus

NASA Technical Reports Server (NTRS)

Cloutier, P. A.; Stewart, B. K.; Taylor, H. A., Jr.

1992-01-01

Data obtained by various instruments on the Pioneer-Venus spacecraft were used to study the conservation of momentum flux from the solar wind through the dayside ionopause into the thermal Venus ionosphere. A consistent pressure deficit was found below the ionopause, with a strong dependence on solar wind pressure. Independent of solar wind pressure, the pressure deficit was found to decrease with decreasing altitude below the ionopause. Measurements of this pressure deficit (missing pressure) are presented as a function of altitude for various solar wind conditions. The identity of the missing pressure component and the correlation with solar wind pressure are discussed.

Collisionless solar wind protons: A comparison of kinetic and hydrodynamic descriptions

NASA Technical Reports Server (NTRS)

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.

ULYSSES comes full circle, before revisiting the Sun's poles

NASA Astrophysics Data System (ADS)

1998-04-01

From its unique perspective, Ulysses has provided scientists with the very first all-round map of the heliosphere, the huge bubble in space filled by the Sun's wind. The Earth swims deep inside the heliosphere, and gusts and shocks in the solar wind can harm satellites, power supplies and ommunications. They may also affect our planet's weather. A better grasp of the solar weather in the heliosphere is therefore one of the major aims of ESA's science programme. In a project of international cooperation between ESA and NASA, Ulysses was launched towards Jupiter in October 1990 by the US space shuttle Discovery. Arriving in February 1992, Ulysses stole energy from the giant planet in a slingshot manoeuvre and was propelled back towards the Sun in an elongated orbit almost at right angles to the ecliptic plane, where the Earth and other planets circle the Sun. "This month Ulysses returns to the point in space where its out-of-ecliptic journey began, but Jupiter isn't there," explains Richard Marsden, ESA's project scientist for Ulysses. "Following its own inexorable path around the Sun, Jupiter is far away on the opposite side of the Solar System. So Ulysses' course will not be changed a second time. The spacecraft is now in effect a man-made comet, forever bound into a 6-year polar orbit around the Sun." Ulysses now starts its second orbit. It will travel over the poles of the Sun in 2000-2001 just as the count of dark sunspots is expected to reach a maximum. With its operational life extended for the Ulysses Solar Maximum Mission, the spacecraft will find the heliosphere much stormier than during its first orbit. Discoveries so far Like its mythical namesake, Ulysses has already had an eventful voyage of discovery. Its unique trajectory has provided the scientific teams with a new perspective, from far out in space and especially in the previously unknown regions of the heliosphere over the Sun's poles. Passing within 9.8 degrees of the polar axis, the highly slanted orbit took Ulysses to solar latitudes greater than 70 degrees for a total of 234 days -- first in the southern hemisphere and then in the north. Also of great interest was the rapid passage from the south to the north, via the Sun's equatorial region, during which Ulysses covered 160 degrees in solar latitude in less than a year. Nine onboard experiments have gathered data continuously since launch, for international teams totalling 150 scientists. Some instruments detect the outward-blowing solar wind and its magnetic field, which create the heliosphere. Others record cosmic rays coming in from the Galaxy, which are strongly influenced by the solar wind. Ulysses picks up natural radio signals emitted by the Sun, the planets and the heliosphere itself. Innovative techniques identify alien atoms and dust particles infiltrating the heliosphere from interstellar space. Ulysses is also a key member of a network of interplanetary spacecraft making observations of enigmatic bursts of gamma rays originating in the far reaches of the Universe. New facts about the fast solar wind were among Ulysses' most fundamental discoveries. The typical solar wind emerging from the Sun's equatorial zone is variable but relatively slow, at 350-400 kilometres per second. The fast wind blows at a steady 750 kilometres per second. It comes from cool regions of the solar atmosphere called coronal holes which (when the Sun is quiet) are close to the poles and fairly small. Yet Ulysses found the fast wind fanning out to fill two-thirds of the volume of the heliosphere. The boundary between the two windstreams is unexpectedly sharp. The magnetic field of the Sun turns out to be strangely uniform at all latitudes in the heliosphere. Close to the visible surface of the Sun, the magnetic field is strongest over the poles, but this intensification disappears at Ulysses' distance. Apparently magnetic pressure in the solar wind averages out the differences in field strength. On the other hand Ulysses discovered unusually strong magnetic waves in the polar regions. Another surprise concerns unexpected connections between the polar and equatorial regions. Rhythmic variations in the intensity of energetic particles and cosmic rays, recorded by Ulysses at high latitudes, originate in effects of the Sun's rotation much closer to the equator. Scientists are debating how their picture of the magnetic field in the heliosphere must change, to make sense of the Ulysses observations. Without this new knowledge of the solar wind's behaviour, and its widespread effects, shocks felt in the Earth's vicinity would remain incomprehensible. For two centuries, sketchy links between sunspots, auroras and magnetic storms have puzzled scientists. Results from Ulysses and other solar spacecraft, including ESA's SOHO and Cluster II, are expected to transform human understanding of solar-terrestrial events. The task is urgent because astronauts and technological systems are becoming ever more vulnerable to the stormy Sun. After the quiet Sun, a peak of activity When Ulysses conducted the first-ever investigation of the high-latitude heliosphere, the Sun was quiet, being near the minimum of solar activity. As scientists expected, the circumstances were ideal for revealing the underlying structure of the Sun's atmosphere and the solar wind, in their simplest form. With the first phase of the voyage safely and very productively completed, Ulysses faces a new challenge, as it continues along its unique path. Obeying a cycle of roughly eleven years, the Sun is once again becoming restless as sunspot activity builds towards the next peak around 2000. When Ulysses revisits the polar regions at that time it will encounter conditions vastly different from those of 1994-95. The international mission of exploration has already given a new and thought-provoking view of the heliosphere. Its findings at solar maximum are guaranteed to do the same, and to give new insights into the gusts and shocks in the solar wind that affect the Earth most severely. "Gone will be the stable picture dominated by the fast solar wind," Richard Marsden predicts. "Most likely this will have been replaced by variability at all latitudes, with slow and fast wind streams jostling one another for prime position. But what exactly awaits Ulysses remains to be seen. Just like the first orbit, the second is truly a voyage into the unknown." Illustrations accompanying this release can be found at the following World Wide Web address: http://helio.estec.esa.nl/ulysses/artwork.html For more information, please contact : ESA Public Relations Division Tel : +33(0)1.53.69.71.55 Fax : +33(0)1.53.69.76.90 Richard Marsden Ulysses Project Scientist, ESTEC Tel : +31.(0)71.565.3583 Fax: +31(0)71.565.4697

IPS analysis on relationship among velocity, density and temperature of the solar wind

NASA Astrophysics Data System (ADS)

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.

KSC-98pc1131

NASA Image and Video Library

1998-09-18

KENNEDY SPACE CENTER, FLA. -- The Spartan solar-observing deployable spacecraft is lifted from its work stand to move it to a payload canister in the Multi-Payload Processing Facility at KSC. Spartan is one of the payloads for the STS-95 mission, scheduled to launch Oct. 29. Spartan is a solar physics spacecraft designed to perform remote sensing of the hot outer layers of the sun's atmosphere or corona. The objective of the observations is to investigate the mechanisms causing the heating of the solar corona and the acceleration of the solar wind which originates in the corona. Other research payloads include the Hubble Space Telescope Orbital Systems Test Platform, the International Extreme Ultraviolet Hitchhiker, and the SPACEHAB single module with experiments on space flight and the aging process

Solar Wind Five

NASA Technical Reports Server (NTRS)

Neugebauer, M. (Editor)

1983-01-01

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

Intermittency of solar wind on scale 0.01-16 Hz.

NASA Astrophysics Data System (ADS)

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 straightforwardly by investigating the density spectrum which should be slaved to the incompressible velocity spectrum. Density discontinuities on times up to t 30-60 s are defined by intermittency of velocity turbulent field. Solar wind intermittency and many or most of its discontinuities are produced by MHD turbulence in this time interval. It is possible that many or even most of the current structures in the solar wind, particularly inertial range structures that contribute to the tails of the PDFs. Complex non-gaussian behaviour on smaller times is described by dissipation rate nonhomogeneity of statistical moments for density field in a random flow.

Summary of NASA-Lewis Research Center solar heating and cooling and wind energy programs

NASA Technical Reports Server (NTRS)

Vernon, R. W.

1975-01-01

NASA is planning to construct and operate a solar heating and cooling system in conjunction with a new office building being constructed at Langley Research Center. The technology support for this project will be provided by a solar energy program underway at NASA's Lewis Research Center. The solar program at Lewis includes: testing of solar collectors with a solar simulator, outdoor testing of collectors, property measurements of selective and nonselective coatings for solar collectors, and a solar model-systems test loop. NASA-Lewis has been assisting the National Science Foundation and now the Energy Research and Development Administration in planning and executing a national wind energy program. The areas of the wind energy program that are being conducted by Lewis include: design and operation of a 100 kW experimental wind generator, industry-designed and user-operated wind generators in the range of 50 to 3000 kW, and supporting research and technology for large wind energy systems. An overview of these activities is provided.

Filamentation instability of magnetosonic waves in the solar wind environment

NASA Technical Reports Server (NTRS)

Kuo, S. P.; Lee, M. C.

1989-01-01

Intense magnetosonic waves, originally propagating at the right angle with the interplanetary magnetic field, can excite a purely growing mode along the interplanetary magnetic field together with two symmetric magnetosonic sidebands propagating obliquely across the magnetic field. This instability process leads to the filamentation of the magnetosonic pump waves. These two excited magnetosonic sideband modes propagate together perpendicularly across the magnetic field and, meanwhile, form a standing wave pattern along the magnetic field. The thresholds of this filamentation instability can be exceeded in the solar wind environment. It is predicted that the density fluctuations produced by the filamentation instability along the interplanetary magnetic field have wavelengths greater than, at least, a few earth radii. The polarization of the obliquely propagating magnetosonic waves excited by the filamentation instability is determined by the characteristics of the magnetosonic pump waves and the environmental plasmas.

Time variation analysis of the daily Forbush decrease indices

NASA Astrophysics Data System (ADS)

Patra, Sankar Narayan; Ghosh, Koushik; Panja, Subhash Chandra

2011-08-01

In the present paper we have analyzed the daily Forbush decrease indices from January 1, 1967 to December 31, 2003. First filtering the time series by Simple Exponential Smoothing, we have applied Scargle Method of Periodogram on the processed time series in order to search for its time variation. Study exhibits periodicities around 174, 245, 261, 321, 452, 510, 571, 584, 662, 703, 735, 741, 767, 774, 820, 970, 1062, 1082, 1489, 1715, 2317, 2577, 2768, 3241 and 10630 days with confidence levels higher than 90%. Some of these periods are significantly similar to the observed periodicities of other solar activities, like solar filament activity, solar electron flare occurrence, solar-flare rate, solar proton events, solar neutrino flux, solar irradiance, cosmic ray intensity and flare, spectrum of the sunspot, solar wind, southern coronal hole area and solar cycle, which may suggest that the Forbush decrease behaves similarly to these solar activities and these activities may have a common origin.

Solar wind composition

NASA Technical Reports Server (NTRS)

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

1995-01-01

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

High-quality weather data for grid integration studies

NASA Astrophysics Data System (ADS)

Draxl, C.

2016-12-01

As variable renewable power penetration levels increase in power systems worldwide, renewable integration studies are crucial to ensure continued economic and reliable operation of the power grid. In this talk we will shed light on requirements for grid integration studies as far as wind and solar energy are concerned. Because wind and solar plants are strongly impacted by weather, high-resolution and high-quality weather data are required to drive power system simulations. Future data sets will have to push limits of numerical weather prediction to yield these high-resolution data sets, and wind data will have to be time-synchronized with solar data. Current wind and solar integration data sets will be presented. The Wind Integration National Dataset (WIND) Toolkit is the largest and most complete grid integration data set publicly available to date. A meteorological data set, wind power production time series, and simulated forecasts created using the Weather Research and Forecasting Model run on a 2-km grid over the continental United States at a 5-min resolution is now publicly available for more than 126,000 land-based and offshore wind power production sites. The Solar Integration National Dataset (SIND) is available as time synchronized with the WIND Toolkit, and will allow for combined wind-solar grid integration studies. The National Solar Radiation Database (NSRDB) is a similar high temporal- and spatial resolution database of 18 years of solar resource data for North America and India. Grid integration studies are also carried out in various countries, which aim at increasing their wind and solar penetration through combined wind and solar integration data sets. We will present a multi-year effort to directly support India's 24x7 energy access goal through a suite of activities aimed at enabling large-scale deployment of clean energy and energy efficiency. Another current effort is the North-American-Renewable-Integration-Study, with the aim of providing a seamless data set across borders for a whole continent, to simulate and analyze the impacts of potential future large wind and solar power penetrations on bulk power system operations.

Comets as natural laboratories: Interpretations of the structure of the inner heliosphere

NASA Astrophysics Data System (ADS)

Ramanjooloo, Yudish; Jones, Geraint H.; Coates, Andrew J.; Owens, Mathew J.

2015-11-01

Much has been learnt about the heliosphere’s structure from in situ solar wind spacecraft observations. Their coverage is however limited in time and space. Comets can be considered to be natural laboratories of the inner heliosphere, as their ion tails trace the solar wind flow. Solar wind conditions influence comets’ induced magnetotails, formed through the draping of the heliospheric magnetic field by the velocity shear in the mass-loaded solar wind.I present a novel imaging technique and software to exploit the vast catalogues of amateur and professional images of comet ion tails. My projection technique uses the comet’s orbital plane to sample its ion tail as a proxy for determining multi-latitudinal radial solar wind velocities in each comet’s vicinity. Making full use of many observing stations from astrophotography hobbyists to professional observatories and spacecraft, this approach is applied to several comets observed in recent years. This work thus assesses the validity of analysing comets’ ion tails as complementary sources of information on dynamical heliospheric phenomena and the underlying continuous solar wind.Complementary velocities, measured from folding ion rays and a velocity profile map built from consecutive images, are derived as an alternative means of quantifying the solar wind-cometary ionosphere interaction, including turbulent transient phenomena such as coronal mass ejections. I review the validity of these techniques by comparing near-Earth comets to solar wind MHD models (ENLIL) in the inner heliosphere and extrapolated measurements by ACE to the orbit of comet C/2004 Q2 (Machholz), a near-Earth comet. My radial velocities are mapped back to the solar wind source surface to identify sources of the quiescent solar wind and heliospheric current sheet crossings. Comets were found to be good indicators of solar wind structure, but the quality of results is strongly dependent on the observing geometry.

Subauroral Ion-neutral Coupling During the March 2015 Superstorm

NASA Astrophysics Data System (ADS)

Zhang, S.; Erickson, P. J.; Foster, J. C.; Holt, J. M.; Coster, A. J.; Makela, J. J.; Noto, J.; Meriwether, J. W.; Otsuka, Y.; Nicolls, M. J.; McCready, M. A.

2015-12-01

The arrival of solar Coronal Mass Ejection materials overlapping a high-speed solar wind stream originated from a nearby coronal hole caused huge magnetic disturbances during March 17-18, 2015. We have coordinated an international campaign to monitor their geospace effects using ground-based facilities, including incoherent scatter radars and Fabry-Perot Interferometers in the America sectors and other instruments in East Asia sectors, forming an observational network along approximately the 60W/120E meridional circle. The presentation will provide highlights of these observations, with a focus on the ion-neutral coupling processes at subauroral and mid-latitudes. One of the most stiking findings is the northward neutral wind surge, observed in multiple sites, accompanying strong westward winds developed at earlier times. We ascribe this unexpected wind disturbances to Subauroal Polarization Stream (SAPS) asscoated strong plasma flows driving ion-neutral coupling. SAPS and strong ion flow were observed by Millstone Hill ISR and DMSP in situ measurements. We will also report the Millstone Hill ISR observations of a significant enhancement in the storm-time molecular ion composition in the F1-region height. This enhancement appears to be caused by strong vertical ion drift due to penetration electric fields.

Self consistent MHD modeling of the solar wind from coronal holes with distinct geometries

NASA Technical Reports Server (NTRS)

Stewart, G. A.; Bravo, S.

1995-01-01

Utilizing an iterative scheme, a self-consistent axisymmetric MHD model for the solar wind has been developed. We use this model to evaluate the properties of the solar wind issuing from the open polar coronal hole regions of the Sun, during solar minimum. We explore the variation of solar wind parameters across the extent of the hole and we investigate how these variations are affected by the geometry of the hole and the strength of the field at the coronal base.

A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 - 24 Minimum

NASA Astrophysics Data System (ADS)

Liou, Kan; Wu, Chin-Chun

2016-12-01

Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23 - 24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth's orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind region (SWR) can have a direct influence on the solar wind parameters near the Earth. In this study, we analyze solar wind plasma and magnetic field data of hourly values acquired by Ulysses. It is found that the solar wind, when averaging over the first (1995.6 - 1995.8) and third (2006.9 - 2008.2) Ulysses' perihelion ({˜} 1.4 AU) crossings, was about the same speed, but significantly less dense ({˜} 34 %) and cooler ({˜} 20 %), and the total magnetic field was {˜} 30 % weaker during the third compared to the first crossing. It is also found that the SWR was {˜} 50 % wider in the third ({˜} 68.5^deg; in heliographic latitude) than in the first ({˜} 44.8°) solar orbit. The observed latitudinal increase in the SWR is sufficient to explain the excessive decline in the near-Earth solar wind density during the recent solar minimum without speculating that the total solar output may have been decreasing. The observed SWR inflation is also consistent with a cooler solar wind in the SC-23/24 than in the SC-22/23 minimum. Furthermore, the ratio of the high-to-low latitude photospheric magnetic field (or equatorward magnetic pressure force), as observed by the Mountain Wilson Observatory, is smaller during the third than the first Ulysses' perihelion orbit. These findings suggest that the smaller equatorward magnetic pressure at the Sun may have led to the latitudinally-wider SRW observed by Ulysses in SC-23/24 minimum.

Dynamics of the solar wind and its interaction with bodies in the solar system

NASA Technical Reports Server (NTRS)

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.

Elemental abundances in corotating events

NASA Technical Reports Server (NTRS)

Vonrosenvinge, T. T.; Mcguire, R. E.

1986-01-01

Large, persistent solar-wind streams in 1973 and 1974 produced corotating interaction regions which accelerated particles to energies of a few MeV/nucleon. The proton to helium ratio (H/He) reported was remarkably constant at a value (22 + or - 5) equal to that in the solar wind (32 + or - 3), suggesting that particles were being accelerated directly out of the solar wind. Preliminary results from a similar study approximately 11 years (i.e., one solar cycle) later are reported. Corotating events were identified by surveying the solar wind data, energetic particle time-histories and anisotropies. This data was all obtained from the ISEE-3/ICE spacecraft. These events also show H/He ratios similar to that in the solar wind. In addition, other corotating events were examined at times when solar flare events could have injected particles into the corresponding corotating interaction regions. It was found that in these cases there is evidence for H/He ratios which are significantly different from that of the solar wind but which are consistent with the range of values found in solar flare events.

Propagation of Interplanetary Disturbances in the Outer Heliosphere

NASA Technical Reports Server (NTRS)

Wang, Chi

2005-01-01

Contents include the following: 1. We have developed a one-dimensional, spherically symmetric, multi-fluid MHD model that includes solar wind protons and electrons, pickup ions, and interstellar neutral hydrogen. This model advances the existing solar wind models for the outer heliosphere in two important ways: one is that it distinguishes solar wind protons from pickup ions, and the other is that it allows for energy transfer from pickup ions to the solar wind protons. Model results compare favorably with the Voyager 2 observations. 2. 2. Solar wind slowdown and interstellar neutral density. The solar wind in the outer heliosphere is fundamentally different from that in the inner heliosphere since the effects of interstellar neutrals become significant. 3. ICME propagation from the inner to outer heliosphere. Large coronal mass ejections (CMEs) have major effects on the structure of the solar wind and the heliosphere. The plasma and magnetic field can be compressed ahead of interplanetary CMEs. 4. During the current solar cycle (Cycle 23), several major CMEs associated with solar flares produced large transient shocks which were observed by widely-separated spacecraft such as Wind at Earth and Voyager 2 beyond 60 AU. Using data from these spacecraft, we use the multi-fluid model to investigate shock propagation and interaction in the heliosphere. Specifically, we studied the Bastille Day 2000, April 2001 and Halloween 2003 events. 5. Statistical properties of the solar wind in the outer heliosphere. In a collaboration with L.F. Burlaga of GSFC, it is shown that the basic statistical properties of the solar wind in the outer heliosphere can be well produced by our model. We studied the large-scale heliospheric magnetic field strength fluctuations as a function of distance from the Sun during the declining phase of a solar cycle, using our numerical model with observations made at 1 AU during 1995 as input. 6. Radial heliospheric magnetic field events. The heliospheric magnetic field (HMF) direction, on average, conforms well to the Parker spiral.

Solar Wind Helium Abundance as a Function of Speed and Heliographic Latitude: Variation through a Solar Cycle

NASA Technical Reports Server (NTRS)

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.

Variation of Solar, Interplanetary and Geomagnetic Parameters during Solar Cycles 21-24

NASA Astrophysics Data System (ADS)

Oh, Suyeon; Kim, Bogyeong

2013-06-01

The length of solar cycle 23 has been prolonged up to about 13 years. Many studies have speculated that the solar cycle 23/24 minimum will indicate the onset of a grand minimum of solar activity, such as the Maunder Minimum. We check the trends of solar (sunspot number, solar magnetic fields, total solar irradiance, solar radio flux, and frequency of solar X-ray flare), interplanetary (interplanetary magnetic field, solar wind and galactic cosmic ray intensity), and geomagnetic (Ap index) parameters (SIG parameters) during solar cycles 21-24. Most SIG parameters during the period of the solar cycle 23/24 minimum have remarkably low values. Since the 1970s, the space environment has been monitored by ground observatories and satellites. Such prevalently low values of SIG parameters have never been seen. We suggest that these unprecedented conditions of SIG parameters originate from the weakened solar magnetic fields. Meanwhile, the deep 23/24 solar cycle minimum might be the portent of a grand minimum in which the global mean temperature of the lower atmosphere is as low as in the period of Dalton or Maunder minimum.

An empirical polytrope law for solar wind thermal electrons between 0.45 and 4.76 AU: Voyager 2 and Mariner 10

NASA Technical Reports Server (NTRS)

Sittler, E. C., Jr.; Scudder, J. D.

1979-01-01

Empirical evidence is presented that solar wind thermal electrons obey a polytrope law with polytrope index gamma = 1.175 plus or minus 0.03. The Voyager 2 and Mariner 10 data used as evidence are compared and discussed. The theoretical predictions that solar wind thermal electrons in the asymptotic solar wind should obey a polytrope law with polytrope index gamma = 1.16 plus or minus. The widespread impressions in the literature that solar wind electrons behave more like an isothermal than adiabatic gas, and the arguments that Coulomb collisions are the dominant stochastic process shaping observed electron distribution functions in the solar wind are reexamined, reviewed and evaluated. The assignment of the interplanetary potential as equal to approximately seven times the temperature of the thermal electrons is discussed.

Three-Dimensional Magnetohydrodynamic Modeling of the Solar Wind Including Pickup Protons and Turbulence Transport

NASA Technical Reports Server (NTRS)

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.

Status of Knowledge after Ulysses and SOHO: Session 2: Investigate the Links between the Solar Surface, Corona, and Inner Heliosphere.

NASA Technical Reports Server (NTRS)

Suess, Steven

2006-01-01

As spacecraft observations of the heliosphere have moved from exploration into studies of physical processes, we are learning about the linkages that exist between different parts of the system. The past fifteen years have led to new ideas for how the heliospheric magnetic field connects back to the Sun and to how that connection plays a role in the origin of the solar wind. A growing understanding these connections, in turn, has led to the ability to use composition, ionization state, the microscopic state of the in situ plasma, and energetic particles as tools to further analyze the linkages and the underlying physical processes. Many missions have contributed to these investigations of the heliosphere as an integrated system. Two of the most important are Ulysses and SOHO, because of the types of measurements they make, their specific orbits, and how they have worked to complement each other. I will review and summarize the status of knowledge about these linkages, with emphasis on results from the Ulysses and SOHO missions. Some of the topics will be the global heliosphere at sunspot maximum and minimum, the physics and morphology of coronal holes, the origin(s) of slow wind, SOHO-Ulysses quadrature observations, mysteries in the propagation of energetic particles, and the physics of eruptive events and their associated current sheets. These specific topics are selected because they point towards the investigations that will be carried out with Solar Orbiter (SO) and the opportunity will be used to illustrate how SO will uniquely contribute to our knowledge of the underlying physical processes.

Microgrid Control Strategy Utlizing Thermal Energy Storage With Renewable Solar And Wind Power Generation

DTIC Science & Technology

2016-06-01

13 Figure 6. Vertical Axis Wind Turbines and Photovoltaic Solar Panels ....................15 Figure 7. Solar Sunny Boy Inverter...16 Figure 8. Wind Turbine Inverters...1. Comparison of Energy Storage. Adapted from [16], [18], [19]. ................10 Table 2. DC Operating Voltage of Wind Turbine Inverters

Analysis of off-grid hybrid wind turbine/solar PV water pumping systems

USDA-ARS?s Scientific Manuscript database

While many remote water pumping systems exist (e.g. mechanical windmills, solar photovoltaic , wind-electric, diesel powered), very few combine both the wind and solar energy resources to possibly improve the reliability and the performance of the system. In this paper, off-grid wind turbine (WT) a...

Oxygen Pickup Ions Measured by MAVEN Outside the Martian Bow Shock

NASA Astrophysics Data System (ADS)

Rahmati, A.; Cravens, T.; Larson, D. E.; Lillis, R. J.; Dunn, P.; Halekas, J. S.; Connerney, J. E. P.; Eparvier, F. G.; Thiemann, E.; Mitchell, D. L.; Jakosky, B. M.

2015-12-01

The MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft entered orbit around Mars on September 21, 2014 and has since been detecting energetic oxygen pickup ions by its SEP (Solar Energetic Particles) and SWIA (Solar Wind Ion Analyzer) instruments. The oxygen pickup ions detected outside the Martian bowshock and in the upstream solar wind are associated with the extended hot oxygen exosphere of Mars, which is created mainly by the dissociative recombination of molecular oxygen ions with electrons in the ionosphere. We use analytic solutions to the equations of motion of pickup ions moving in the undisturbed upstream solar wind magnetic and motional electric fields and calculate the flux of oxygen pickup ions at the location of MAVEN. Our model calculates the ionization rate of oxygen atoms in the exosphere based on the hot oxygen densities predicted by Rahmati et al. (2014), and the sources of ionization include photo-ionization, charge exchange, and electron impact ionization. The photo-ionization frequency is calculated using the FISM (Flare Irradiance Spectral Model) solar flux model, based on MAVEN EUVM (Extreme Ultra-Violet Monitor) measurements. The frequency of charge exchange between a solar wind proton and an oxygen atom is calculated using MAVEN SWIA solar wind proton flux measurements, and the electron impact ionization frequency is calculated based on MAVEN SWEA (Solar Wind Electron Analyzer) solar wind electron flux measurements. The solar wind magnetic field used in the model is from the measurements taken by MAVEN MAG (magnetometer) in the upstream solar wind. The good agreement between our predicted pickup oxygen fluxes and the MAVEN SEP and SWIA measured ones confirms detection of oxygen pickup ions and these model-data comparisons can be used to constrain models of hot oxygen densities and photochemical escape flux.

Understanding non-equilibrium collisional and expansion effects in the solar wind with Parker Solar Probe

NASA Astrophysics Data System (ADS)

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Energy conversion through mass loading of escaping ionospheric ions for different Kp values

NASA Astrophysics Data System (ADS)

Yamauchi, Masatoshi; Slapak, Rikard

2018-01-01

By conserving momentum during the mixing of fast solar wind flow and slow planetary ion flow in an inelastic way, mass loading converts kinetic energy to other forms - e.g. first to electrical energy through charge separation and then to thermal energy (randomness) through gyromotion of the newly born cold ions for the comet and Mars cases. Here, we consider the Earth's exterior cusp and plasma mantle, where the ionospheric origin escaping ions with finite temperatures are loaded into the decelerated solar wind flow. Due to direct connectivity to the ionosphere through the geomagnetic field, a large part of this electrical energy is consumed to maintain field-aligned currents (FACs) toward the ionosphere, in a similar manner as the solar wind-driven ionospheric convection in the open geomagnetic field region. We show that the energy extraction rate by the mass loading of escaping ions (ΔK) is sufficient to explain the cusp FACs, and that ΔK depends only on the solar wind velocity accessing the mass-loading region (usw) and the total mass flux of the escaping ions into this region (mloadFload), as ΔK ˜ -mloadFloadu2sw/4. The expected distribution of the separated charges by this process also predicts the observed flowing directions of the cusp FACs for different interplanetary magnetic field (IMF) orientations if we include the deflection of the solar wind flow directions in the exterior cusp. Using empirical relations of u0 ∝ Kp + 1.2 and Fload ∝ exp(0.45Kp) for Kp = 1-7, where u0 is the solar wind velocity upstream of the bow shock, ΔK becomes a simple function of Kp as log10(ΔK) = 0.2 ṡ Kp + 2 ṡ log10(Kp + 1.2) + constant. The major contribution of this nearly linear increase is the Fload term, i.e. positive feedback between the increase of ion escaping rate Fload through the increased energy consumption in the ionosphere for high Kp, and subsequent extraction of more kinetic energy ΔK from the solar wind to the current system by the increased Fload. Since Fload significantly increases for increased flux of extreme ultraviolet (EUV) radiation, high EUV flux may significantly enhance this positive feedback. Therefore, the ion escape rate and the energy extraction by mass loading during ancient Earth, when the Sun is believed to have emitted much higher EUV flux than at present, could have been even higher than the currently available highest values based on Kp = 9. This raises a possibility that the ion escape has substantially contributed to the evolution of the Earth's atmosphere.

CIR-XL recurring for several years

NASA Astrophysics Data System (ADS)

Dósa, Melinda; Erdös, Géza

2016-04-01

The heliospheric magnetic flux is determined from the radial component of the magnetic field vector measured onboard interplanetary space probes. Earlier Ulysses research has shown remarkable independence of the flux from heliographic latitude. Here we are investigating whether any longitudinal variation exist in the 50 year long OMNI magnetic data set. When determining the heliographic longitude of the plasma source, correction was applied for the solar wind travel time. Significant recurrent enhancements of the magnetic flux was observed during the declining phase of the solar cycles. These flux enhancements are associated with co-rotating interaction regions (CIR) lasting several years. The recurrence period is slightly faster than the Carrington Rotation rate. The same, long lasting recurring features can be observed when plotting the deviation angle of the solar wind velocity vector from the radial direction. However, the deviation angle is small - in order of a few degrees - and cannot account for the observed flux increases. An increase of the magnetic field is clearly caused by the plasma compression associated to CIRs. Comparing interplanetary data with synoptic maps of the coronal magnetic field (PFSS modell) and coronal temperature data of ACE, we came to the possible explanation that these long-term structures are caused by fast speed solar wind originating from coronal holes. This results supports the idea that magnetic field lines from coronal holes spread out and reach to low latitudes as well. The recurrent longitudinal variation of the magnetic flux during the declining phase of the solar cycle has impact on the modulation of cosmic rays as well as on the frequency and intensity of space weather events.

Properties of Minor Ions In the Solar Wind and Implications for the Background Solar Wind Plasma

NASA Technical Reports Server (NTRS)

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.

Asteroid surface processes: Experimental studies of the solar wind on reflectance and optical properties of asteroids

NASA Technical Reports Server (NTRS)

Mcfadden, Lucy-Ann

1991-01-01

The effect of the solar wind on the optical properties of meteorites was studied to determine whether the solar wind can alter the properties of ordinary chondrite parent bodies resulting in the spectral properties of S-type asteroids. The existing database of optical properties of asteroids was analyzed to determine the effect of solar wind in altering asteroid surface properties.

Molecular Substrate Alteration by Solar Wind Radiation Documented on Flown Genesis Mission Array Materials

NASA Technical Reports Server (NTRS)

Calaway, Michael J.; Stansbery, Eileen K.

2006-01-01

The Genesis spacecraft sampling arrays were exposed to various regimes of solar wind during flight that included: 313.01 days of high-speed wind from coronal holes, 335.19 days of low-speed inter-stream wind, 191.79 days of coronal mass ejections, and 852.83 days of bulk solar wind at Lagrange 1 orbit. Ellipsometry measurements taken at NASA s Johnson Space Center show that all nine flown array materials from the four Genesis regimes have been altered by solar wind exposure during flight. These measurements show significant changes in the optical constant for all nine ultra-pure materials that flew on Genesis when compared with their non-flight material standard. This change in the optical constant (n and k) of the material suggests that the molecular structure of the all nine ultra-pure materials have been altered by solar radiation. In addition, 50 samples of float-zone and czochralski silicon bulk array ellipsometry results were modeled with an effective medium approximation layer (EMA substrate layer) revealing a solar radiation molecular damage zone depth below the SiO2 native oxide layer ranging from 392 to 613 . This bulk solar wind radiation penetration depth is comparable to the depth of solar wind implantation depth of Mg measured by SIMS and SARISA.

Microphysics of Waves and Instabilities in the Solar Wind and their Macro Manifestations in the Corona and Interplanetary Space

NASA Technical Reports Server (NTRS)

Habbal, Shadia R.; Gurman, Joseph (Technical Monitor)

2003-01-01

Investigations of the physical processes responsible for the acceleration of the solar wind were pursued with the development of two new solar wind codes: a hybrid code and a 2-D MHD code. Hybrid simulations were performed to investigate the interaction between ions and parallel propagating low frequency ion cyclotron waves in a homogeneous plasma. In a low-beta plasma such as the solar wind plasma in the inner corona, the proton thermal speed is much smaller than the Alfven speed. Vlasov linear theory predicts that protons are not in resonance with low frequency ion cyclotron waves. However, non-linear effect makes it possible that these waves can strongly heat and accelerate protons. This study has important implications for study of the corona and the solar wind. Low frequency ion cyclotron waves or Alfven waves are commonly observed in the solar wind. Until now, it is believed that these waves are not able to heat the solar wind plasma unless some cascading processes transfer the energy of these waves to high frequency part. However, this study shows that these waves may directly heat and accelerate protons non-linearly. This process may play an important role in the coronal heating and the solar wind acceleration, at least in some parameter space.

Wind and solar resource data sets: Wind and solar resource data sets

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Interplanetary gas. XX - Does the radial solar wind speed increase with latitude

NASA Technical Reports Server (NTRS)

Brandt, J. C.; Harrington, R. S.; Roosen, R. G.

1975-01-01

The astrometric technique used to derive solar wind speeds from ionic comet-tail orientations has been used to test the suggestion that the radial solar wind speed is higher near the solar poles than near the equator. We find no evidence for the suggested latitude variation.

75 FR 59291 - In the Matter of: Certain Wind and Solar-Powered Light Posts and Street Lamps; Notice of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-27

... INTERNATIONAL TRADE COMMISSION [Inv. No. 337-TA-736] In the Matter of: Certain Wind and Solar... solar-powered light posts and street lamps by reason of infringement of the claimed design of U.S... certain wind and solar- [[Page 59292

Remotely Distinguishing and Mapping Endogenic Water on the Moon

NASA Technical Reports Server (NTRS)

Klima, Rachel L.; Petro, Noah E.

2017-01-01

Water and/or hydroxyl detected remotely on the lunar surface originates from several sources: (i) comets and other exogenous debris; (ii) solar wind implantation; (iii) the lunar interior. While each of these sources is interesting in its own right, distinguishing among them is critical for testing hypotheses for the origin and evolution of the Moon and our Solar System. Existing spacecraft observations are not of high enough spectral resolution to uniquely characterize the bonding energies of the hydroxyl molecules that have been detected. Nevertheless, the spatial distribution and associations of H, OH- or H2O with specific lunar lithologies provide some insight into the origin of lunar hydrous materials. The global distribution of OH-/H2O as detected using infrared spectroscopic measurements from orbit is here examined, with particular focus on regional geological features that exhibit OH-/H2O absorption band strengths that differ from their immediate surroundings.

Taking Venus models to new dimensions.

NASA Astrophysics Data System (ADS)

Murawski, K.

1997-11-01

Space plasma physicists in Poland and Japan have gained new insights into the interaction between the solar wind and Venus. Computer simulations of this 3D global interaction between the solar wind and nonmagnetized bodies have enabled greater understanding of the large-scale processes involved in such phenomena. A model that offers improved understanding of the solar wind interaction with Venus (as well as other nonmagnetized bodies impacted by the solar wind) has been developed. In this model, the interaction of the solar wind with the ionosphere of Venus is studied by calculating numerical solutions of the 3D MHD equations for two-component, chemically reactive plasma. The author describes the innovative model.

Ion Isotropy and Ion Resonant Waves in the Solar Wind: Cassini Observations

NASA Technical Reports Server (NTRS)

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.

EVIDENCE FOR QUASI-ADIABATIC MOTION OF CHARGED PARTICLES IN STRONG CURRENT SHEETS IN THE SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malova, H. V.; Popov, V. Yu.; Grigorenko, E. E.

We investigate quasi-adiabatic dynamics of charged particles in strong current sheets (SCSs) in the solar wind, including the heliospheric current sheet (HCS), both theoretically and observationally. A self-consistent hybrid model of an SCS is developed in which ion dynamics is described at the quasi-adiabatic approximation, while the electrons are assumed to be magnetized, and their motion is described in the guiding center approximation. The model shows that the SCS profile is determined by the relative contribution of two currents: (i) the current supported by demagnetized protons that move along open quasi-adiabatic orbits, and (ii) the electron drift current. The simplestmore » modeled SCS is found to be a multi-layered structure that consists of a thin current sheet embedded into a much thicker analog of a plasma sheet. This result is in good agreement with observations of SCSs at ∼1 au. The analysis of fine structure of different SCSs, including the HCS, shows that an SCS represents a narrow current layer (with a thickness of ∼10{sup 4} km) embedded into a wider region of about 10{sup 5} km, independently of the SCS origin. Therefore, multi-scale structuring is very likely an intrinsic feature of SCSs in the solar wind.« less

Laser Subdivision of the Genesis Concentrator Target Sample 60000

NASA Technical Reports Server (NTRS)

Lauer, Howard V., Jr.; Burkett, P. J.; Rodriquez, M. C.; Nakamura-Messenger, K.; Clemett, S. J.; Gonzales, C. P.; Allton, J. H.; McNamara, K. M.; See, T. H.

2013-01-01

The Genesis Allocation Committee received a request for 1 square centimeter of the diamond-like-carbon (DLC) concentrator target for the analysis of solar wind nitrogen isotopes. The target consists of a single crystal float zone (FZ) silicon substrate having a thickness on the order of 550 micrometers with a 1.5-3.0 micrometer-thick coating of DLC on the exposed surface. The solar wind is implanted shallowly in the front side DLC. The original target was a circular quadrant with a radius of 3.1 cm; however, the piece did not survive intact when the spacecraft suffered an anomalous landing upon returning to Earth on September 8, 2004. An estimated 75% of the DLC target was recovered in at least 18 fragments. The largest fragment, Genesis sample 60000, has been designated for this allocation and is the first sample to be subdivided using our laser scribing system Laser subdivision has associated risks including thermal diffusion of the implant if heating occurs and unintended breakage during cleavage. A careful detailed study and considerable subdividing practice using non-flight FZ diamond on silicon, DOS, wafers has considerably reduced the risk of unplanned breakage during the cleaving process. In addition, backside scribing reduces the risk of possible thermal excursions affecting the implanted solar wind, implanted shallowly in the front side DLC.

Summary of NASA Lewis Research Center solar heating and cooling and wind energy programs

NASA Technical Reports Server (NTRS)

Vernon, R. W.

1975-01-01

Plans for the construction and operation of a solar heating and cooling system in conjunction with a office building being constructed at Langley Research Center, are discussed. Supporting research and technology includes: testing of solar collectors with a solar simulator, outdoor testing of collectors, property measurements of selective and nonselective coatings for solar collectors, and a solar model-systems test loop. The areas of a wind energy program that are being conducted include: design and operation of a 100-kW experimental wind generator, industry-designed and user-operated wind generators in the range of 50 to 3000 kW, and supporting research and technology for large wind energy systems. An overview of these activities is provided.

Modeling solar wind with boundary conditions from interplanetary scintillations

DOE PAGES

Manoharan, P.; Kim, T.; Pogorelov, N. V.; ...

2015-09-30

Interplanetary scintillations make it possible to create three-dimensional, time- dependent distributions of the solar wind velocity. Combined with the magnetic field observations in the solar photosphere, they help perform solar wind simulations in a genuinely time-dependent way. Interplanetary scintillation measurements from the Ooty Radio Astronomical Observatory in India provide directions to multiple stars and may assure better resolution of transient processes in the solar wind. In this paper, we present velocity distributions derived from Ooty observations and compare them with those obtained with the Wang-Sheeley-Arge (WSA) model. We also present our simulations of the solar wind flow from 0.1 AUmore » to 1 AU with the boundary conditions based on both Ooty and WSA data.« less

Solar wind velocity and temperature in the outer heliosphere

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

3D Visualization of Solar Data: Preparing for Solar Orbiter and Parker Solar Probe

NASA Astrophysics Data System (ADS)

Mueller, D.; Nicula, B.; Felix, S.; Verstringe, F.; Bourgoignie, B.; Csillaghy, A.; Berghmans, D.; Jiggens, P.; Ireland, J.; Fleck, B.

2017-12-01

Solar Orbiter and Parker Solar Probe will focus on exploring the linkage between the Sun and the heliosphere. These new missions will collect unique data that will allow us to study, e.g., the coupling between macroscopic physical processes to those on kinetic scales, the generation of solar energetic particles and their propagation into the heliosphere and the origin and acceleration of solar wind plasma. Combined with the several petabytes of data from NASA's Solar Dynamics Observatory, the scientific community will soon have access to multi­dimensional remote-sensing and complex in-situ observations from different vantage points, complemented by petabytes of simulation data. Answering overarching science questions like "How do solar transients drive heliospheric variability and space weather?" will only be possible if the community has the necessary tools at hand. In this contribution, we will present recent progress in visualizing the Sun and its magnetic field in 3D using the open-source JHelioviewer framework, which is part of the ESA/NASA Helioviewer Project.

Ions with low charges in the solar wind as measured by SWICS on board Ulysses. [Solar Wind Ion Composition Spectrometer

NASA Technical Reports Server (NTRS)

Geiss, J.; Ogilvie, K. W.; Von Steiger, R.; Mall, U.; Gloeckler, G.; Galvin, A. B.; Ipavich, F.; Wilken, B.; Gliem, F.

1992-01-01

We present new data on rare ions in the solar wind. Using the Ulysses-SWICS instrument with its very low background we have searched for low-charge ions during a 6-d period of low-speed solar wind and established sensitive upper limits for many species. In the solar wind, we found He(1+)/He(2+) of less than 5 x 10 exp -4. This result and the charge state distributions of heavier elements indicate that all components of the investigated ion population went through a regular coronal expansion and experienced the typical electron temperatures of 1 to 2 million Kelvin. We argue that the virtual absence of low-charge ions demonstrates a very low level of nonsolar contamination in the source region of the solar wind sample we studied. Since this sample showed the FlP effect typical for low-speed solar wind, i.e., an enhancement in the abundances of elements with low first ionization potential, we conclude that this enhancement was caused by an ion-atom separation mechanism operating near the solar surface and not by foreign material in the corona.

Dynamics of Magnetopause Reconnection in Response to Variable Solar Wind Conditions

NASA Astrophysics Data System (ADS)

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.

Quiet-time electron increases, a measure of conditions in the outer solar system

NASA Technical Reports Server (NTRS)

Fisk, L. A.; Vanhollebeke, M.

1972-01-01

One possible explanation for quiet-time electron increases, increases in the intensity of 3-12 MeV interplanetary electrons that have been reported by McDonald, Cline and Simnett, is discussed. It is argued that the electrons in quiet-time increases are galactic in origin, but that the observed increases are not the result of any variation in the modulation of these particles in the inner solar system. It is suggested instead that quiet-time increases may occur when more electrons than normal penetrate a modulating region that lies far beyond the orbit of earth. The number of electrons penetrating this region may increase when field lines that have experienced an unusually large random walk in the photosphere are carried by the solar wind out to the region. As evidence for this increased random walk, it is shown that five solar rotations before most of the quiet-time increases there is an extended period when the amplitude of the diurnal anisotropy, as is measured by the Deep River neutron monitor, is relatively low. Five rotations delay time implies that the proposed modulating region lies at approximately 30 AU from the Sun, assuming that the average solar wind speed is constant over this distance at approximately 400 km/sec.

SCR and GCR exposure ages of plagioclase grains from lunar soil

NASA Technical Reports Server (NTRS)

Etique, P.; Baur, H.; Signer, P.; Wieler, R.

1986-01-01

The concentrations of solar wind implanted Ar-36 in mineral grains extracted from lunar soils show that they were exposed to the solar wind on the lunar surface for an integrated time of 10E4 to 10E5 years. From the bulk soil 61501 plagioclase separates of 8 grain size ranges was prepared. The depletion of the implanted gases was achieved by etching aliquot samples of 4 grain sizes to various degrees. The experimental results pertinent to the present discussion are: The spallogenic Ne is, as in most plagioclases from lunar soils, affected by diffusive losses and of no use. The Ar-36 of solar wind origin amounts to (2030 + or - 100) x 10E-8 ccSTP/g in the 150 to 200 mm size fraction and shows that these grains were exposed to the solar wind for at least 10,000 years. The Ne-21/Ne-22 ratio of the spallogenic Ne is 0.75 + or - 0.01 and in very good agreement with the value of this ratio in a plagioclase separate from rock 76535. This rock has had a simple exposure history and its plagioclases have a chemical composition quite similar to those studied. In addition to the noble gases, the heavy particle tracks in an aliquot of the 150 to 200 mm plagioclase separate were investigated and found 92% of the grains to contain more than 10E8 tracks/sq cm. This corresponds to a mean track density of (5 + or - 1) x 10E8 tracks/sq cm. The exploration of the exposure history of the plagioclase separates from the soil 61501 do not contradict the model for the regolith dynamics but also fail to prove it.

Contribution of wind energy to the energy balance of a combined solar and wind energy system. Part 1: System description, data acquisition and system performance

NASA Astrophysics Data System (ADS)

Ferger, R.; Machens, U.

1985-05-01

A one-family house was equipped with a combined solar and wind energy system plus a night storage heater to measure the seasonal complementary contribution of wind and solar energy to energy demand. Project implementation, problems encountered and modifications to the initial system are described. Meteorological and operational data and house consumption data were recorded on computer-based measuring system. Data on the combined effects of and interdependence between solar collector and wind energy converter are discussed.

77 FR 72439 - Residential, Business, and Wind and Solar Resource Leases on Indian Land

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-05

... Affairs 25 CFR Part 162 Residential, Business, and Wind and Solar Resource Leases on Indian Land; Final...-2011-0001] RIN 1076-AE73 Residential, Business, and Wind and Solar Resource Leases on Indian Land... adds new regulations to address residential leases, business leases, wind energy evaluation leases, and...

Survey of the spectral properties of turbulence in the solar wind, the magnetospheres of Venus and Earth, at solar minimum and maximum

NASA Astrophysics Data System (ADS)

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 and maximum of the solar cycle we also analyze the spectral similarities and differences between fast and slow wind turbulence. We emphasize the importance of our data survey and analysis in the context of understanding the solar wind turbulence, the exploitation of data bases and as a first step towards developing a (virtual) laboratory for studying solar system plasma turbulence. 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.

78 FR 67138 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-08

... Solar 1, LLC, Copper Mountain Solar 2, LLC, Energia Sierra Juarez U.S., LLC, Flat Ridge 2 Wind Energy LLC, Fowler Ridge II Wind Farm LLC, Mehoopany Wind Energy LLC, Mesquite Power, LLC, Mesquite Solar 1...

Multifluid Simulations of the Global Solar Wind Including Pickup Ions and Turbulence Modeling

NASA Technical Reports Server (NTRS)

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

2011-01-01

I will describe a three-dimensional magnetohydrodynamic model of the solar wind that takes into account turbulent heating of the wind by velocity and magnetic fluctuations as well as a variety of effects produced by interstellar pickup protons. The interstellar pickup protons are treated in the model as one fluid and the protons and electrons are treated together as a second fluid. The model equations include a Reynolds decomposition of the plasma velocity and magnetic field into mean and fluctuating quantities, as well as energy transfer from interstellar pickup protons to solar wind protons that results in the deceleration of the solar wind. The model is used to simulate the global steady-state structure of the solar wind in the region from 0.3 to 100 AU. The simulation assumes that the background magnetic field on the Sun is either a dipole (aligned or tilted with respect to the solar rotation axis) or one that is deduced from solar magnetograms.

Contribution of strong discontinuities to the power spectrum of the solar wind.

PubMed

Borovsky, Joseph E

2010-09-10

Eight and a half years of magnetic field measurements (2(22) samples) from the ACE spacecraft in the solar wind at 1 A.U. are analyzed. Strong (large-rotation-angle) discontinuities in the solar wind are collected and measured. An artificial time series is created that preserves the timing and amplitudes of the discontinuities. The power spectral density of the discontinuity series is calculated and compared with the power spectral density of the solar-wind magnetic field. The strong discontinuities produce a power-law spectrum in the "inertial subrange" with a spectral index near the Kolmogorov -5/3 index. The discontinuity spectrum contains about half of the power of the full solar-wind magnetic field over this "inertial subrange." Warnings are issued about the significant contribution of discontinuities to the spectrum of the solar wind, complicating interpretation of spectral power and spectral indices.

Prompt Disappearance and Emergence of Radiation Belt Magnetosonic Waves Induced by Solar Wind Dynamic Pressure Variations

NASA Astrophysics Data System (ADS)

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.

Elsaesser variable analysis of fluctuations in the ion foreshock and undisturbed solar wind

NASA Technical Reports Server (NTRS)

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.

A comparison of empirical and experimental O7+, O8+, and O/H values, with applications to terrestrial solar wind charge exchange

NASA Astrophysics Data System (ADS)

Whittaker, Ian C.; Sembay, Steve

2016-07-01

Solar wind charge exchange occurs at Earth between the neutral planetary exosphere and highly charged ions of the solar wind. The main challenge in predicting the resultant photon flux in the X-ray energy bands is due to the interaction efficiency, known as the α value. This study produces experimental α values at the Earth, for oxygen emission in the range of 0.5-0.7 keV. Thirteen years of data from the Advanced Composition Explorer are examined, comparing O7+ and O8+ abundances, as well as O/H to other solar wind parameters allowing all parameters in the αO7,8+ calculation to be estimated based on solar wind velocity. Finally, a table is produced for a range of solar wind speeds giving average O7+ and O8+ abundances, O/H, and αO7,8+ values.

Costs of solar and wind power variability for reducing CO2 emissions.

PubMed

Lueken, Colleen; Cohen, Gilbert E; Apt, Jay

2012-09-04

We compare the power output from a year of electricity generation data from one solar thermal plant, two solar photovoltaic (PV) arrays, and twenty Electric Reliability Council of Texas (ERCOT) wind farms. The analysis shows that solar PV electricity generation is approximately one hundred times more variable at frequencies on the order of 10(-3) Hz than solar thermal electricity generation, and the variability of wind generation lies between that of solar PV and solar thermal. We calculate the cost of variability of the different solar power sources and wind by using the costs of ancillary services and the energy required to compensate for its variability and intermittency, and the cost of variability per unit of displaced CO(2) emissions. We show the costs of variability are highly dependent on both technology type and capacity factor. California emissions data were used to calculate the cost of variability per unit of displaced CO(2) emissions. Variability cost is greatest for solar PV generation at $8-11 per MWh. The cost of variability for solar thermal generation is $5 per MWh, while that of wind generation in ERCOT was found to be on average $4 per MWh. Variability adds ~$15/tonne CO(2) to the cost of abatement for solar thermal power, $25 for wind, and $33-$40 for PV.

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

NASA Technical Reports Server (NTRS)

Ofman, Leon

2001-01-01

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

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

NASA Technical Reports Server (NTRS)

Ofman, Leon

2000-01-01

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

Global solar wind variations over the last four centuries.

PubMed

Owens, M J; Lockwood, M; Riley, P

2017-01-31

The most recent "grand minimum" of solar activity, the Maunder minimum (MM, 1650-1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth's magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima.

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

DTIC Science & Technology

2012-03-05

subsonic corona below the critical point, resulting in an increased scale height and mass flux, while keeping the kinetic energy of the flow fairly...Approved for public release; distribution is unlimited. tubes with small expansion factors the heating occurs in the supersonic corona, where the energy ...goes into the kinetic energy of the solar wind, increasing the flow speed [Leer and Holzer, 1980; Pneuman, 1980]. Using this model and a sim- plified

Inertial Range Turbulence of Fast and Slow Solar Wind at 0.72 AU and Solar Minimum

NASA Astrophysics Data System (ADS)

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.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-29

... Affairs 25 CFR Part 162 Residential, Business, and Wind and Solar Resource Leases on Indian Land; Proposed...-0001] RIN 1076-AE73 Residential, Business, and Wind and Solar Resource Leases on Indian Land AGENCY... leases, and solar resource development leases on Indian land, and would therefore remove the existing...

Solar wind temperature observations in the outer heliosphere

NASA Technical Reports Server (NTRS)

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.

Using Dawn to Observe SEP Events Past 2 AU

NASA Astrophysics Data System (ADS)

Villarreal, M. N.; Russell, C. T.; Prettyman, T. H.

2017-12-01

The launch of the STEREO spacecraft provided much insight into the longitudinal and radial distribution of solar energetic particles (SEPs) relative to their origin site. However, almost all of the observations of SEP events have been made exclusively near 1 AU. The Dawn mission, which orbited around Vesta before arriving at Ceres, provides an opportunity to analyze these events at much further distances. Although Dawn's Gamma Ray and Neutron Detector (GRaND) is not optimized for SEP characterization, it is sensitive to protons greater than 4 MeV, making it capable of detecting a solar energetic particle event in its vicinity. Solar energetic particles in this area of the solar system are important as they are believed to cause sputtering at bodies such as Ceres and comets (Villarreal et al., 2017; Wurz et al., 2015). In this study, we use Dawn's GRaND data from 2011-2015 when Dawn was at distances between 2-3 AU. We compare the SEP events seen by Dawn with particle measurements at 1 AU using STEREO, Wind, and ACE to understand how the SEP events evolved past 1 AU.References: Villarreal, M. N., et al. (2017), The dependence of the Cerean exosphere on solar energetic particle events, Astrophys. J. Lett., 838, L8.Wurz, P. et al. (2015), Solar wind sputtering of dust on the surface of 67P/Churyumov-Gerasimenko, A&A, 583, A22.

Using Dawn to Observe SEP Events Past 2 AU

NASA Astrophysics Data System (ADS)

Villarreal, Michaela; Russell, Christopher T.; Prettyman, Thomas H.

2017-10-01

The launch of the STEREO spacecraft provided much insight into the longitudinal and radial distribution of solar energetic particles (SEPs) relative to their origin site. However, almost all of the observations of SEP events have been made exclusively near 1 AU. The Dawn mission, which orbited around Vesta before arriving at Ceres, provides an opportunity to analyze these events at much further distances. Although Dawn's Gamma Ray and Neutron Detector (GRaND) is not optimized for SEP characterization, it is sensitive to protons greater than 4 MeV, making it capable of detecting a solar energetic particle event in its vicinity. Solar energetic particles in this area of the solar system are important as they are believed to cause sputtering at bodies such as Ceres and comets (Villarreal et al., 2017; Wurz et al., 2015). In this study, we use Dawn’s GRaND data from 2011-2015 when Dawn was at distances between 2-3 AU. We compare the SEP events seen by Dawn with particle measurements at 1 AU using STEREO, Wind, and ACE to understand how the SEP events evolved past 1 AU.References: Villarreal, M. N., et al. (2017), The dependence of the Cerean exosphere on solar energetic particle events, Astrophys. J. Lett., 838, L8.Wurz, P. et al. (2015), Solar wind sputtering of dust on the surface of 67P/Churyumov-Gerasimenko, A&A, 583, A22.

Magnetosphere-Ionosphere-Thermosphere Response to Quasi-periodic Oscillations in Solar Wind Driving Conditions

NASA Astrophysics Data System (ADS)

Liu, J.; Wang, W.; Zhang, B.; Huang, C.

2017-12-01

Periodical oscillations with periods of several tens of minutes to several hours are commonly seen in the Alfven wave embedded in the solar wind. It is yet to be known how the solar wind oscillation frequency modulates the solar wind-magnetosphere-ionosphere coupled system. Utilizing the Coupled Magnetosphere-Ionosphere-Thermosphere Model (CMIT), we analyzed the magnetosphere-ionosphere-thermosphere system response to IMF Bz oscillation with periods of 10, 30, and 60 minutes from the perspective of energy budget and electrodynamic coupling processes. Our results indicate that solar wind energy coupling efficiency depends on IMF Bz oscillation frequency; energy coupling efficiency, represented by the ratio between globally integrated Joule heating and Epsilon function, is higher for lower frequency IMF Bz oscillation. Ionospheric Joule heating dissipation not only depends on the direct solar wind driven process but also is affected by the intrinsic nature of magnetosphere (i.e. loading-unloading process). In addition, ionosphere acts as a low-pass filter and tends to filter out very high-frequency solar wind oscillation (i.e. shorter than 10 minutes). Ionosphere vertical ion drift is most sensitive to IMF Bz oscillation compared to hmF2, and NmF2, while NmF2 is less sensitive. This can account for not synchronized NmF2 and hmF2 response to penetration electric fields in association with fast solar wind changes. This research highlights the critical role of IMF Bz oscillation frequency in constructing energy coupling function and understanding electrodynamic processes in the coupled solar wind-magnetosphere-ionosphere system.

THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC MODELING OF THE SOLAR WIND INCLUDING PICKUP PROTONS AND TURBULENCE TRANSPORT

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Analysis of Wind Forces on Roof-Top Solar Panel

NASA Astrophysics Data System (ADS)

Panta, Yogendra; Kudav, Ganesh

2011-03-01

Structural loads on solar panels include forces due to high wind, gravity, thermal expansion, and earthquakes. International Building Code (IBC) and the American Society of Civil Engineers are two commonly used approaches in solar industries to address wind loads. Minimum Design Loads for Buildings and Other Structures (ASCE 7-02) can be used to calculate wind uplift loads on roof-mounted solar panels. The present study is primarily focused on 2D and 3D modeling with steady, and turbulent flow over an inclined solar panel on the flat based roof to predict the wind forces for designing wind management system. For the numerical simulation, 3-D incompressible flow with the standard k- 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).

Analysis of Solar Wind Precipitation on Mars Using MAVEN/SWIA Observations of Spacecraft-Scattered Ions

NASA Astrophysics Data System (ADS)

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 an instrument point-of-view and evaluate the instrument sensitivity to ENAs. 1. Halekas, J. S., et al. (2015), Geophys. Res. Lett., 42, doi:10.1002/2015GL064693 2. Halekas, J. S., et al. (2017), J. Geophys. Res., 122, doi:10.1002/2016JA023167

Wave Modeling of the Solar Wind.

PubMed

Ofman, Leon

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

Long-term changes in solar wind elemental and isotopic ratios - A comparison of two lunar ilmenites of different antiquities

NASA Technical Reports Server (NTRS)

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.

Interaction between Solar Wind and Lunar Magnetic Anomalies observed by Kaguya MAP-PACE

NASA Astrophysics Data System (ADS)

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 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 were observed, the simultaneously measured electrons were often heated and the incident solar wind ions were sometimes slightly decelerated. At ~50km altitude, when the reflected ions were observed, proton scattering at the lunar surface clearly disappeared. It suggests that there exists an area on the lunar surface where solar wind does not impact. At ~10km altitude, the interaction between the solar wind ions and the lunar magnetic anomalies was remarkable with clear deceleration of the incident solar wind ions and heating of the reflected ions as well as significant heating of the electrons. Calculating velocity moments including density, velocity, temperature of the ions and electrons, we have found that there exists 100km scale regions over strong magnetic anomalies where plasma parameters are quite different from the outside. Solar wind ions observed at 10km altitude show several different behaviors such as deceleration without heating and heating in a limited region inside the magnetic anomalies that may be caused by the magnetic field structure. The deceleration of the solar wind has the same ΔE/q (ΔE : deceleration energy, q: charge) for different species, which constraints the possible mechanisms of the interaction between solar wind and magnetic anomalies.

The Solar Wind Depletion (SWD) event of 26 April 1999: Triggering of an auroral pseudobreakup event

NASA Technical Reports Server (NTRS)

Zhou, X.; Tsurutani, B.; Gonzalez, W.

2000-01-01

The interplanetary solar wind depletion (SWD) event of 26 April 1999 and its magnetospheric consequences are examined. The SWD event is characterized by a solar wind density decrease from [similar to] 3.0 to 0.7 cm(sup -3) leading to a solar wind ram pressure decrease from [similar to] 2.0 to 0.2 nPa. This SWD onset is followed by a dipolarization of nightside magnetospheric fields.

Solar Wind Earth Exchange Project (SWEEP)

DTIC Science & Technology

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

Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona

NASA Astrophysics Data System (ADS)

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.

A Study of the Structure of the Source Region of the Solar Wind in Support of a Solar Probe Mission

NASA Technical Reports Server (NTRS)

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.

Some remarks on waves in the solar wind

NASA Technical Reports Server (NTRS)

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 it has been found that Langmuir waves are associated with magnetic holes. This may help to elucidate the nature of magnetic holes. Nonlinear processes are important in the transformation of wave energy to panicle energy. Some recent examples from WIND data will be shown.

Solar power. [comparison of costs to wind, nuclear, coal, oil and gas

NASA Technical Reports Server (NTRS)

Walton, A. L.; Hall, Darwin C.

1990-01-01

This paper describes categories of solar technologies and identifies those that are economic. It compares the private costs of power from solar, wind, nuclear, coal, oil, and gas generators. In the southern United States, the private costs of building and generating electricity from new solar and wind power plants are less than the private cost of electricity from a new nuclear power plant. Solar power is more valuable than nuclear power since all solar power is available during peak and midpeak periods. Half of the power from nuclear generators is off-peak power and therefore is less valuable. Reliability is important in determining the value of wind and nuclear power. Damage from air pollution, when factored into the cost of power from fossil fuels, alters the cost comparison in favor of solar and wind power. Some policies are more effective at encouraging alternative energy technologies that pollute less and improve national security.

The Delta II with ACE aboard is prepared for liftoff from Pad 17A, CCAS

NASA Technical Reports Server (NTRS)

1997-01-01

After launch tower retraction, the Boeing Delta II expendable launch vehicle carrying the Advanced Composition Explorer (ACE) undergoes final preparations for liftoff in the predawn hours of Aug. 24, 1997, at Launch Complex 17A, Cape Canaveral Air Station. This is the second Delta launch under the Boeing name and the first from Cape Canaveral. ACE with its combination of nine sensors and instruments will investigate the origin and evolution of solar phenomenon, the formation of solar corona, solar flares and acceleration of the solar wind. ACE was built for NASA by the Johns Hopkins Applied Physics Laboratory and is managed by the Explorer Project Office at NASA's Goddard Space Flight Center. The lead scientific institution is the California Institute of Technology.

On the generation of solar spicules and Alfvénic waves

NASA Astrophysics Data System (ADS)

Martínez-Sykora, J.; De Pontieu, B.; Hansteen, V. H.; Rouppe van der Voort, L.; Carlsson, M.; Pereira, T. M. D.

2017-06-01

In the lower solar atmosphere, the chromosphere is permeated by jets known as spicules, in which plasma is propelled at speeds of 50 to 150 kilometers per second into the corona. The origin of the spicules is poorly understood, although they are expected to play a role in heating the million-degree corona and are associated with Alfvénic waves that help drive the solar wind. We compare magnetohydrodynamic simulations of spicules with observations from the Interface Region Imaging Spectrograph and the Swedish 1-m Solar Telescope. Spicules are shown to occur when magnetic tension is amplified and transported upward through interactions between ions and neutrals or ambipolar diffusion. The tension is impulsively released to drive flows, heat plasma (through ambipolar diffusion), and generate Alfvénic waves.

Planetary X-ray studies: past, present and future

NASA Astrophysics Data System (ADS)

Branduardi-Raymont, Graziella

2016-07-01

Our solar system is a fascinating physics laboratory and X-ray observations are now firmly established as a powerful diagnostic tool of the multiple processes taking place in it. The science that X-rays reveal encompasses solar, space plasma and planetary physics, and the response of bodies in the solar system to the impact of the Sun's activity. This talk will review what we know from past observations and what we expect to learn in the short, medium and long term. Observations with Chandra and XMM-Newton have demonstrated that the origin of Jupiter's bright soft X-ray aurorae lies in the Charge eXchange (CX) process, likely to involve the interaction with atmospheric neutrals of local magnetospheric ions, as well as those carried in the solar wind. At higher energies electron bremsstrahlung is thought to be the X-ray emitting mechanism, while the whole planetary disk acts as a mirror for the solar X-ray flux via Thomson and fluorescent scattering. This 'X-ray mirror' phenomenon is all that is observed from Saturn's disk, which otherwise lacks X-ray auroral features. The Earth's X-ray aurora is bright and variable and mostly due to electron bremsstrahlung and line emission from atmospheric species. Un-magnetised planets, Venus and Mars, do not show X-ray aurorae but display the interesting combination of mirroring the solar X-ray flux and producing X-rays by Solar Wind Charge eXchange (SWCX) in their exospheres. These processes respond to different solar stimulation (photons and solar wind plasma respectively) hence their relative contributions are seen to vary according to the Sun's output. Present and future of planetary X-ray studies are very bright. We are preparing for the arrival of the Juno mission at Jupiter this summer and for coordinated observations with Chandra and XMM-Newton on the approach and later during Juno's orbital phase. These will allow direct correlation of the local plasma conditions with the X-ray emissions and the establishment of the relative contributions of different processes. SWCX X-ray emission from the Earth's exosphere is turning from unwanted variable background in astrophysical observations to a novel and global diagnostic tool for investigating solar-terrestrial interactions: this underpins the development of the ESA-CAS joint mission SMILE (Solar Wind Magnetosphere Ionosphere Link Explorer) due for launch in 2021. On the longer term ATHENA (Advanced Telescope for High ENergy Astrophysics, launch 2028) will provide planetary targets with vastly improved X-ray sensitivity on that currently afforded by XMM-Newton.

Eta Carinae: A Demanding Mistress

NASA Technical Reports Server (NTRS)

Gull, Theodore

2012-01-01

In the 1840's a southern star, Eta Argus, brightened to rival Sirius for nearly a decade, then faded. Today, we see the Homunculus, an hourglass figure with tutu, a dusty shell exceeding 12 solar masses expanding outward at 500 km/s. Many observers have systematically studied the massive binary total shrouded by interacting winds and its ejecta. More recently 3-D wind-wind collision models have begun to explain the extended structures resolved by Hubble Space Telescope. Now Herschel Space Observatory infrared scans are revealing wind interaction emissions and complex molecules left over from the dust that formed out of gas originally overabundant in nitrogen and greatly-depleted in oxygen and carbon. Many questions remain to be answered: What is the dust that formed in the 1840s event? What are the end states of the two massive companions ... SN, GRB, Hypernova? and When

GPP Webinar: Market Outlook and Innovations in Wind and Solar Power

EPA Pesticide Factsheets

Green Power Partnership webinar reviewing the state of the renewable energy industry as a whole, with a focus on wind and solar power and exploring recent marketplace innovations in wind and solar power and renewable energy purchases.

Generation of Kappa Distributions in Solar Wind at 1 au

NASA Astrophysics Data System (ADS)

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.

Stationarity of extreme bursts in the solar wind

NASA Astrophysics Data System (ADS)

Moloney, N. R.; Davidsen, J.

2014-05-01

Recent results have suggested that the statistics of bursts in the solar wind vary with solar cycle. Here, we show that this variation is basically absent if one considers extreme bursts. These are defined as threshold-exceeding events over the range of high thresholds for which their number decays as a power law. In particular, we find that the distribution of duration times and energies of extreme bursts in the solar wind ɛ parameter and similar observables are independent of the solar cycle and in this sense stationary, and show robust asymptotic power laws with exponents that are independent of the specific threshold. This is consistent with what has been observed for solar flares and, thus, provides evidence in favor of a link between solar flares and extreme bursts in the solar wind.

Recent perspectives in solar physics - Elemental composition, coronal structure and magnetic fields, solar activity

NASA Technical Reports Server (NTRS)

Newkirk, G., Jr.

1975-01-01

Elemental abundances in the solar corona are studied. Abundances in the corona, solar wind and solar cosmic rays are compared to those in the photosphere. The variation in silicon and iron abundance in the solar wind as compared to helium is studied. The coronal small and large scale structure is investigated, emphasizing magnetic field activity and examining cosmic ray generation mechanisms. The corona is observed in the X-ray and EUV regions. The nature of coronal transients is discussed with emphasis on solar-wind modulation of galactic cosmic rays. A schematic plan view of the interplanetary magnetic field during sunspot minimum is given showing the presence of magnetic bubbles and their concentration in the region around 4-5 AU by a fast solar wind stream.

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

NASA Technical Reports Server (NTRS)

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

1978-01-01

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

Composition of the Solar Wind

NASA Technical Reports Server (NTRS)

Suess, S. T.

2007-01-01

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

A reexamination of the QBO period modulation by the solar cycle

NASA Astrophysics Data System (ADS)

Fischer, P.; Tung, K. K.

2008-04-01

Using the updated Singapore wind from 1953 to 2007 for the lower stratosphere 70-10 hPa, courtesy of Barbara Naujokat of Free University of Berlin, we examine the variation of the period of the Quasi-Biennial Oscillation (QBO) as a function of height and its modulation in time by the 11-year solar cycle. The analysis is supplemented by the ERA-40 reanalysis up to 1 hPa. Previously, it was reported that the descent of the easterly shear zone tends to stall near 30 hPa during solar minimum, leading to a lengthened QBO westerly duration near 44-50 hPa and the reported anticorrelation of the westerly duration and the solar cycle. Using an objective method, continuous wavelet transform (CWT), for the determination of local QBO period, we find that the whole QBO period is almost invariant with respect to height, so that the stalling mechanism affects only the partition of the whole period between easterly and westerly durations. Using this longest data set available for equatorial stratospheric wind, which spans five and half solar cycles (six solar minima), we find that in three solar minima, the QBO period is lengthened, while in the remaining almost three solar cycles, the QBO period is lengthened instead at solar maxima. We suggest that the decadal variation of the QBO period originates in the upper stratosphere, where the solar-ozone radiative influence is strong. The solar modulation of the QBO period is found to be nonstationary; the averaged effect cannot be determined unless the data record is much longer. In shorter records, the correlation can change sign, as we have found in segments of the longest record available, with or without lag.

Impacts of wind stilling on solar radiation variability in China

PubMed Central

Lin, Changgui; Yang, Kun; Huang, Jianping; Tang, Wenjun; Qin, Jun; Niu, Xiaolei; Chen, Yingying; Chen, Deliang; Lu, Ning; Fu, Rong

2015-01-01

Solar dimming and wind stilling (slowdown) are two outstanding climate changes occurred in China over the last four decades. The wind stilling may have suppressed the dispersion of aerosols and amplified the impact of aerosol emission on solar dimming. However, there is a lack of long-term aerosol monitoring and associated study in China to confirm this hypothesis. Here, long-term meteorological data at weather stations combined with short-term aerosol data were used to assess this hypothesis. It was found that surface solar radiation (SSR) decreased considerably with wind stilling in heavily polluted regions at a daily scale, indicating that wind stilling can considerably amplify the aerosol extinction effect on SSR. A threshold value of 3.5 m/s for wind speed is required to effectively reduce aerosols concentration. From this SSR dependence on wind speed, we further derived proxies to quantify aerosol emission and wind stilling amplification effects on SSR variations at a decadal scale. The results show that aerosol emission accounted for approximately 20% of the typical solar dimming in China, which was amplified by approximately 20% by wind stilling. PMID:26463748

Probability Density Functions of the Solar Wind Driver of the Magnetopshere-Ionosphere System

NASA Astrophysics Data System (ADS)

Horton, W.; Mays, M. L.

2007-12-01

The solar-wind driven magnetosphere-ionosphere system is a complex dynamical system in that it exhibits (1) sensitivity to initial conditions; (2) multiple space-time scales; (3) bifurcation sequences with hysteresis in transitions between attractors; and (4) noncompositionality. This system is modeled by WINDMI--a network of eight coupled ordinary differential equations which describe the transfer of power from the solar wind through the geomagnetic tail, the ionosphere, and ring current in the system. The model captures both storm activity from the plasma ring current energy, which yields a model Dst index result, and substorm activity from the region 1 field aligned current, yielding model AL and AU results. The input to the model is the solar wind driving voltage calculated from ACE solar wind parameter data, which has a regular coherent component and broad-band turbulent component. Cross correlation functions of the input-output data time series are computed and the conditional probability density function for the occurrence of substorms given earlier IMF conditions are derived. The model shows a high probability of substorms for solar activity that contains a coherent, rotating IMF with magnetic cloud features. For a theoretical model of the imprint of solar convection on the solar wind we have used the Lorenz attractor (Horton et al., PoP, 1999, doi:10.10631.873683) as a solar wind driver. The work is supported by NSF grant ATM-0638480.

Three-Dimensional Evolution of Flux-Rope CMEs and Its Relation to the Local Orientation of the Heliospheric Current Sheet

NASA Astrophysics Data System (ADS)

Isavnin, A.; Vourlidas, A.; Kilpua, E. K. J.

2014-06-01

Flux ropes ejected from the Sun may change their geometrical orientation during their evolution, which directly affects their geoeffectiveness. Therefore, it is crucial to understand how solar flux ropes evolve in the heliosphere to improve our space-weather forecasting tools. We present a follow-up study of the concepts described by Isavnin, Vourlidas, and Kilpua ( Solar Phys. 284, 203, 2013). We analyze 14 coronal mass ejections (CMEs), with clear flux-rope signatures, observed during the decay of Solar Cycle 23 and rise of Solar Cycle 24. First, we estimate initial orientations of the flux ropes at the origin using extreme-ultraviolet observations of post-eruption arcades and/or eruptive prominences. Then we reconstruct multi-viewpoint coronagraph observations of the CMEs from ≈ 2 to 30 R⊙ with a three-dimensional geometric representation of a flux rope to determine their geometrical parameters. Finally, we propagate the flux ropes from ≈ 30 R⊙ to 1 AU through MHD-simulated background solar wind while using in-situ measurements at 1 AU of the associated magnetic cloud as a constraint for the propagation technique. This methodology allows us to estimate the flux-rope orientation all the way from the Sun to 1 AU. We find that while the flux-ropes' deflection occurs predominantly below 30 R⊙, a significant amount of deflection and rotation happens between 30 R⊙ and 1 AU. We compare the flux-rope orientation to the local orientation of the heliospheric current sheet (HCS). We find that slow flux ropes tend to align with the streams of slow solar wind in the inner heliosphere. During the solar-cycle minimum the slow solar-wind channel as well as the HCS usually occupy the area in the vicinity of the solar equatorial plane, which in the past led researchers to the hypothesis that flux ropes align with the HCS. Our results show that exceptions from this rule are explained by interaction with the Parker-spiraled background magnetic field, which dominates over the magnetic interaction with the HCS in the inner heliosphere at least during solar-minimum conditions.

Three-Fluid Magnetohydrodynamic Modeling of the Solar Wind in the Outer Heliosphere

NASA Technical Reports Server (NTRS)

Usmanov, Arcadi V.; Goldstein, Melvyn L.; Matthaeus, William H.

2011-01-01

We have developed a three-fluid, fully three-dimensional magnetohydrodynamic model of the solar wind plasma in the outer heliosphere as a co-moving system of solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Our approach takes into account the effects of electron heat conduction and dissipation of Alfvenic turbulence on the spatial evolution of the solar wind plasma and interplanetary magnetic fields. The turbulence transport model is based on the Reynolds decomposition of physical variables into mean and fluctuating components and uses the turbulent phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. We solve the coupled set of the three-fluid equations for the mean-field solar wind and the turbulence equations for the turbulence energy, cross helicity, and correlation length. The equations are written in the rotating frame of reference and include heating by turbulent dissipation, energy transfer from interstellar pickup protons to solar wind protons, and solar wind deceleration due to the interaction with the interstellar hydrogen. The numerical solution is constructed by the time relaxation method in the region from 0.3 to 100 AU. Initial results from the novel model are presented.

Solar wind speed and He I (1083 nm) absorption line intensity

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Identification of Interplanetary Coronal Mass Ejections at 1 AU Using Multiple Solar Wind Plasma Composition Anomalies

NASA Technical Reports Server (NTRS)

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 of both ICMEs and the ambient solar wind.

25 CFR 162.010 - How do I obtain a lease?

Code of Federal Regulations, 2014 CFR

2014-04-01

... subpart E for wind energy evaluation, wind resource, or solar resource leases; and (3) Prospective lessees..., residential, business, wind energy evaluation, wind resource, and solar resource leases will not be advertised...

25 CFR 162.010 - How do I obtain a lease?

Code of Federal Regulations, 2013 CFR

2013-04-01

... subpart E for wind energy evaluation, wind resource, or solar resource leases; and (3) Prospective lessees..., residential, business, wind energy evaluation, wind resource, and solar resource leases will not be advertised...

Role of Concentrating Solar Power in Integrating Solar and Wind Energy: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

Handbook of solar-terrestrial data systems, version 1

NASA Technical Reports Server (NTRS)

1991-01-01

The interaction between the solar wind and the earth's magnetic field creates a large magnetic cavity which is termed the magnetosphere. Energy derived from the solar wind is ultimately dissipated by particle acceleration-precipitation and Joule heating in the magnetosphere-ionosphere. The rate of energy dissipation is highly variable, with peak levels during geomagnetic storms and substorms. The degree to which solar wind and magnetospheric conditions control the energy dissipation processes remains one of the major outstanding questions in magnetospheric physics. A conference on Solar Wind-Magnetospheric Coupling was convened to discuss these issues and this handbook is the result.

The evolution of 1 AU equatorial solar wind and its association with the morphology of the heliospheric current sheet from solar cycles 23 to 24

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, L.; Landi, E.; Zurbuchen, T. H.

2014-09-20

The solar wind can be categorized into three types based on its 'freeze-in' temperature (T {sub freeze-in}) in the coronal source: low T {sub freeze-in} wind mostly from coronal holes, high T {sub freeze-in} wind mostly from regions outside of coronal holes, including streamers (helmet streamer and pseudostreamer), active regions, etc., and transient interplanetary coronal mass ejections (ICMEs) usually possessing the hottest T {sub freeze-in}. The global distribution of these three types of wind has been investigated by examining the most effective T {sub freeze-in} indicator, the O{sup 7+}/O{sup 6+} ratio, as measured by the Solar Wind Ion Composition Spectrometermore » on board the Advanced Composition Explorer (ACE) during 1998-2008 by Zhao et al. In this study, we extend the previous investigation to 2011 June, covering the unusual solar minimum between solar cycles 23 and 24 (2007-2010) and the beginning of solar cycle 24. We find that during the entire solar cycle, from the ascending phase of cycle 23 in 1998 to the ascending phase of cycle 24 in 2011, the average fractions of the low O{sup 7+}/O{sup 6+} ratio (LOR) wind, the high O{sup 7+}/O{sup 6+} ratio (HOR) wind, and ICMEs at 1 AU are 50.3%, 39.4%, and 10.3%, respectively; the contributions of the three types of wind evolve with time in very different ways. In addition, we compare the evolution of the HOR wind with two heliospheric current sheet (HCS) parameters, which indicate the latitudinal standard deviation (SD) and the slope (SL) of the HCS on the synoptic Carrington maps at 2.5 solar radii surface. We find that the fraction of HOR wind correlates with SD and SL very well (slightly better with SL than with SD), especially after 2005. This result verifies the link between the production of HOR wind and the morphology of the HCS, implying that at least one of the major sources of the HOR wind must be associated with the HCS.« less

The GENESIS Mission: Solar Wind Isotopic and Elemental Compositions and Their Implications

NASA Astrophysics Data System (ADS)

Wiens, R. C.; Burnett, D. S.; McKeegan, K. D.; Kallio, A. P.; Mao, P. H.; Heber, V. S.; Wieler, R.; Meshik, A.; Hohenberg, C. M.; Mabry, J. C.; Gilmour, J.; Crowther, S. A.; Reisenfeld, D. B.; Jurewicz, A.; Marty, B.; Pepin, R. O.; Barraclough, B. L.; Nordholt, J. E.; Olinger, C. T.; Steinberg, J. T.

2008-12-01

The GENESIS mission was a novel NASA experiment to collect solar wind at the Earth's L1 point for two years and return it for analysis. The capsule crashed upon re-entry in 2004, but many of the solar-wind collectors were recovered, including separate samples of coronal hole, interstream, and CME material. Laboratory analyses of these materials have allowed higher isotopic precision than possible with current in-situ detectors. To date GENESIS results have been obtained on isotopes of O, He, Ne, Ar, Kr, and Xe on the order of 1% accuracy and precision, with poorer uncertainty on Xe isotopes and significantly better uncertainties on the lighter noble gases. Elemental abundances are available for the above elements as well as Mg, Si, and Fe. When elemental abundances are compared with other in situ solar wind measurements, agreement is generally quite good. One exception is the Ne elemental abundance, which agrees with Ulysses and Apollo SWC results, but not with ACE. Neon is of particular interest because of the uncertainty in the solar Ne abundance, which has significant implications for the standard solar model. Helium isotopic results of material from the different solar wind regimes collected by GENESIS is consistent with isotopic fractionation predictions of the Coulomb drag model, suggesting that isotopic fractionation corrections need to be applied to heavier elements as well when extrapolating solar wind to solar compositions. Noble gas isotopic compositions from GENESIS are consistent with those obtained for solar wind trapped in lunar grains, but have for the first time yielded a very precise Ar isotopic result. Most interesting for cosmochemistry is a preliminary oxygen isotopic result from GENESIS which indicates a solar enrichment of ~4% in 16O relative to the planets, consistent with a photolytic self-shielding phenomenon during solar system formation. Analyses of solar wind N and C isotopes may further elucidate this phenomenon. Preliminary results from GENESIS have been reported for N, and results are still pending for C.

Mapping the Solar Wind from its Source Region into the Outer Corona

NASA Technical Reports Server (NTRS)

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.

Wind and Solar Resource Assessment of Sri Lanka and the Maldives (CD-ROM)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elliott, D.; Schwartz, M.; Scott, G.

2003-08-01

The Wind and Solar Resource Assessment of Sri Lanka and the Maldives CD contains an electronic version of Wind Energy Resource Atlas of Sri Lanka and the Maldives (NREL/TP-500-34518), Solar Resource Assessment for Sri Lanka and the Maldives (NREL/TO-710-34645), Sri Lanka Wind Farm Analysis and Site Selection Assistance (NREL/SR-500-34646), GIS Data Viewer (software and data files with a readme file), and Hourly Solar and Typical Meteorological Year Data with a readme file.

An Analysis of the Use of Energy Audits, Solar Panels, and Wind Turbines to Reduce Energy Consumption from Non Renewable Energy Sources

DTIC Science & Technology

2015-04-15

the Use of Energy Audits, Solar Panels, and Wind Turbines to Reduce Energy Consumption from Non Renewable Energy Sources Energy is a National...Park, NC 27709-2211 Energy Audits, Energy Conservation, Renewable Energy, Solar Energy, Wind Turbine Use, Energy Consumption REPORT DOCUMENTATION PAGE 11...in non peer-reviewed journals: An Analysis of the Use of Energy Audits, Solar Panels, and Wind Turbines to Reduce Energy Consumption from Non

Thomas Gold's Intense Solar Wind; It's evidence in prehistoric petroglyphs recorded along rivers in North and South America

NASA Astrophysics Data System (ADS)

Peratt, A. L.

2008-11-01

A past intense solar outburst and its effect on Earth circa 8,000 BCE was proposed by Gold who based his hypotheses on astronomical and geophysical evidence [1]. The discovery of high-current Z-pinch patterns in Neolithic petroglyphs provides evidence for this occurrence and insight into the origin and meaning of these ancient symbols produced by mankind. These correspond to mankind's visual observations of ancient aurora if the solar wind had increased between one and two orders of magnitude millennia ago [2]. Our data show identical MHD patterns from surveys along 300 km of the Orinoco River (Venezuela), the Chuluut River (Mongolia), the Columbia River (USA), Red Gorge (South Australia) and the Urubamba River (Peru). Three-dimensional, high-fidelity PIC simulations of intense Z-pinches replicate the carved data [3]. 1. T. Gold, Pontificiae Academiae Scientiarvm Scripta Varia, 25, 159, 1962. 2. A. L. Peratt. Trans. Plasma Sci. 35. 778. 2007. 3. A. L. Peratt and W. F. Yao, Physica Scripta, T130, August 2008.

Analysis of data from the plasma composition experiment on the International Sun-Earth Explorer (ISEE 1)

NASA Technical Reports Server (NTRS)

Lennartsson, O. W.

1994-01-01

The Lockheed plasma composition experiment on the ISEE 1 spacecraft has provided one of the largest and most varied sets of data on earth's energetic plasma environment, covering both the solar wind, well beyond the bow shock, and the near equatorial magnetosphere to a distance of almost 23 earth radii. This report is an overview of the last four years of data analysis and archiving. The archiving for NSSDC includes most data obtained during the initial 28-months of instrument operation, from early November 1977 through the end of February 1980. The data products are a combination of spectra (mass and energy angle) and velocity moments. A copy of the data user's guide and examples of the data products are attached as appendix A. The data analysis covers three major areas: solar wind ions upstream and downstream of the day side bowshock, especially He(++) ions; terrestrial ions flowing upward from the auroral regions, especially H(+), O(+), and He(+) ions; and ions of both solar and terrestrial origins in the tail plasma sheet and lobe regions. Copies of publications are attached.

Constraints on the origin of the Moon's atmosphere from observations during a lunar eclipse.

PubMed

Mendillo, M; Baumgardner, J

1995-10-05

The properties of the Moon's rarefied atmosphere, which can be traced through observations of sodium and potassium, provide important insights into the formation and maintenance of atmospheres on other primitive Solar System bodies. The lunar atmosphere is believed to be composed of atoms from the surface rocks and soil, which might have been sputtered by micrometeorites, by ions in the solar wind, or by photons. It might also form by the evaporation of atoms from the hot, illuminated surface. Here we report the detection of sodium emission from the Moon's atmosphere during a total lunar eclipse (which occurs when the Moon is full). The sodium atmosphere is considerably more extended at full Moon than expected--it extends to at least nine lunar radii--and its brightness distribution is incompatible with sources involving either solar-wind or micrometeorite sputtering. This leaves photon sputtering or thermal desorption as the preferred explanations for the lunar atmosphere, and suggests that sunlight might also be responsible for the transient atmospheres of other primitive bodies (such as Mercury).

"Solar-Wind-Rich" Howardite: True Regolith vs. CM-Implanted Components

NASA Technical Reports Server (NTRS)

Cartwright, Julia A.; Mittlefehldt, D. W.; Herrin, J. S.; Hermann, S.; Ott, U.

2011-01-01

Howardite, eucrite and diogenite meteorites (collectively HED) likely originate from asteroid 4-Vesta [1], one of two asteroids targeted by NASA s Dawn mission. Many howardites (polymict breccias of E and D material) contain "regolithic" features, including impact-melt clasts, fragmental breccia clasts, and carbonaceous chondrite fragments. True regolithic nature can be determined through noble gas analysis, as Solar Wind (SW) is implanted into the upper-most surfaces of solar system bodies. Whilst previous work [2] suggested that high siderophile element contents (e.g. Ni of 300-1200 g/g) were regolith indicators, we found no obvious correlation between SW and these indicators in our initial howardite noble gas analyses [3]. We observed CM-like fragments in a number of our howardites, whose textures suggest late addition to the breccia assemblage [4]. As typical CMs contain mixtures of SW (in matrix) and planetary (in clasts) components [5], we investigate the dominance of such components in SW-rich howardites. This will help deter-mine the extent of implanted SW in HED grains vs. SW and planetary gases from CM fragments, and allow better understanding of regolith processes

Solar-wind velocity measurements from near-Sun comets C/2011 W3 (Lovejoy), C/2011 L4 (Pan-STARRS), and C/2012 S1 (ISON)

NASA Astrophysics Data System (ADS)

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 equipment and sensors, rival and sometimes arguably exceed the quality of professional images obtained only 2--3 decades ago. Multiple solar-wind velocity estimates were derived from each image and the results compared to observed and modelled near-Earth solar-wind data. Our unique analysis technique [Ramanjooloo et al., in preparation] allows us to determine the latitudinal variations of the solar wind, heliospheric current-sheet sector boundaries and the boundaries of transient features as a comet with an observable plasma tail probes the inner heliosphere. We present solar-wind velocity measurements derived from multiple observing locations of comets Lovejoy from the 14th -- 19th December 2011, comet Pan-STARRS during 11th -- 16th March 2013 and comet ISON from 12th -- 29th November 2013. Observations were gathered from multiple resources, from the SECCHI heliospheric imagers aboard STEREO A and B [8], the LASCO coronagraphs aboard SOHO [9], as well as ground-based amateur and professional observations coordinated by the CIOC. Overlapping observation sessions from the three spacecraft and ground-based efforts provided the perfect opportunity to use these comets as a diagnostic tool to understand solar-wind variability close to the Sun. We plan to compare our observations to results of suitable simulations [10] of plasma conditions in the corona and inner heliosphere during each of the comets' perihelion passage. The correlation of the solar-wind velocity distribution from different observing locations can provide clues towards the morphology and orientation of the plasma tail. We also attempt to determine the difficult-to-determine non-radial components of the measured solar-wind velocities.

High charge state carbon and oxygen ions in Earth's equatorial quasi-trapping region

NASA Technical Reports Server (NTRS)

Christon, S. P.; Hamilton, D. C.; Gloeckler, G.; Eastmann, T. E.

1994-01-01

Observations of energetic (1.5 - 300 keV/e) medium-to-high charge state (+3 less than or equal to Q less than or equal to +7) solar wind origin C and O ions made in the quasi-trapping region (QTR) of Earth's magnetosphere are compared to ion trajectories calculated in model equatorial magnetospheric magnetic and electric fields. These comparisons indicate that solar wind ions entering the QTR on the nightside as an energetic component of the plasma sheet exit the region on the dayside, experiencing little or no charge exchange on the way. Measurements made by the CHarge Energy Mass (CHEM) ion spectrometer on board the Active Magnetospheric Particle Tracer Explorer/Charge Composition Explorer (AMPTE/CCE) spacecraft at 7 less than L less than 9 from September 1984 to January 1989 are the source of the new results contained herein: quantitative long-term determination of number densities, average energies, energy spectra, local time distributions, and their variation with geomagnetic disturbance level as indexed by Kp. Solar wind primaries (ions with charge states unchanged) and their secondaries (ions with generally lower charge states produced from primaries in the magnetosphere via charge exchange)are observed throughout the QTR and have distinctly different local time variations that persist over the entire 4-year analysis interval. During Kp larger than or equal to 3 deg intervals, primary ion (e.g., O(+6)) densities exhibit a pronounced predawn maximum with average energy minimum and a broad near-local-noon density minimum with average energy maximum. Secondary ion (e.g., O(+5)) densities do not have an identifiable predawn peak, rather they have a broad dayside maximum peaked in local morning and a nightside minimum. During Kp less than or equal to 2(-) intervals, primary ion density peaks are less intense, broader in local time extent, and centered near midnight, while secondary ion density local time variations diminish. The long-time-interval baseline helps to refine and extend previous observations; for example, we show that ionospheric contribution to O(+3)) is negligible. Through comparison with model ion trajectories, we interpret the lack of pronounced secondary ion density peaks colocated with the primary density peaks to indicate that: (1) negligible charge exchange occurs at L greater than 7, that is, solar wind secondaries are produced at L less than 7, and (2) solar wind secondaries do not form a significant portion of the plasma sheet population injected into the QTR. We conclude that little of the energetic solar wind secondary ion population is recirculated through the magnetosphere.

On the Relationship Between Solar Wind Speed, Geomagnetic Activity, and the Solar Cycle Using Annual Values

NASA Technical Reports Server (NTRS)

Wilson, Robert M.; Hathaway, David H.

2008-01-01

The aa index can be decomposed into two separate components: the leading sporadic component due to solar activity as measured by sunspot number and the residual or recurrent component due to interplanetary disturbances, such as coronal holes. For the interval 1964-2006, a highly statistically important correlation (r = 0.749) is found between annual averages of the aa index and the solar wind speed (especially between the residual component of aa and the solar wind speed, r = 0.865). Because cyclic averages of aa (and the residual component) have trended upward during cycles 11-23, cyclic averages of solar wind speed are inferred to have also trended upward.

The large-scale magnetic field in the solar wind. [astronomical models of interplanetary magnetics and the solar magnetic field

NASA Technical Reports Server (NTRS)

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.

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

NASA Technical Reports Server (NTRS)

Farrell, William M.

2011-01-01

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

Use of meteorological information in the risk analysis of a mixed wind farm and solar

NASA Astrophysics Data System (ADS)

Mengelkamp, H.-T.; Bendel, D.

2010-09-01

Use of meteorological information in the risk analysis of a mixed wind farm and solar power plant portfolio H.-T. Mengelkamp*,** , D. Bendel** *GKSS Research Center Geesthacht GmbH **anemos Gesellschaft für Umweltmeteorologie mbH The renewable energy industry has rapidly developed during the last two decades and so have the needs for high quality comprehensive meteorological services. It is, however, only recently that international financial institutions bundle wind farms and solar power plants and offer shares in these aggregate portfolios. The monetary value of a mixed wind farm and solar power plant portfolio is determined by legal and technical aspects, the expected annual energy production of each wind farm and solar power plant and the associated uncertainty of the energy yield estimation or the investment risk. Building an aggregate portfolio will reduce the overall uncertainty through diversification in contrast to the single wind farm/solar power plant energy yield uncertainty. This is similar to equity funds based on a variety of companies or products. Meteorological aspects contribute to the diversification in various ways. There is the uncertainty in the estimation of the expected long-term mean energy production of the wind and solar power plants. Different components of uncertainty have to be considered depending on whether the power plant is already in operation or in the planning phase. The uncertainty related to a wind farm in the planning phase comprises the methodology of the wind potential estimation and the uncertainty of the site specific wind turbine power curve as well as the uncertainty of the wind farm effect calculation. The uncertainty related to a solar power plant in the pre-operational phase comprises the uncertainty of the radiation data base and that of the performance curve. The long-term mean annual energy yield of operational wind farms and solar power plants is estimated on the basis of the actual energy production and it's relation to a climatologically stable long-term reference period. These components of uncertainty are of technical nature and based on subjective estimations rather than on a statistically sound data analysis. And then there is the temporal and spatial variability of the wind speed and radiation. Their influence on the overall risk is determined by the regional distribution of the power plants. These uncertainty components are calculated on the basis of wind speed observations and simulations and satellite derived radiation data. The respective volatility (temporal variability) is calculated from the site specific time series and the influence on the portfolio through regional correlation. For an exemplary portfolio comprising fourteen wind farms and eight solar power plants the annual mean energy production to be expected is calculated, the different components of uncertainty are estimated for each single wind farm and solar power plant and for the portfolio as a whole. The reduction in uncertainty (or risk) through bundling the wind farms and the solar power plants (the portfolio effect) is calculated by Markowitz' Modern Portfolio Theory. This theory is applied separately for the wind farm and the solar power plant bundle and for the combination of both. The combination of wind and photovoltaic assets clearly shows potential for a risk reduction. Even assets with a comparably low expected return can lead to a significant risk reduction depending on their individual characteristics.

Solar wind stream evolution at large heliocentric distances - Experimental demonstration and the test of a model

NASA Technical Reports Server (NTRS)

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.

Measurements of the properties of solar wind plasma relevant to studies of its coronal sources

NASA Technical Reports Server (NTRS)

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.

The Interaction Between the Magnetosphere of Mars and that of Comet Siding Spring

NASA Astrophysics Data System (ADS)

Holmstrom, M.; Futaana, Y.; Barabash, S. V.

2015-12-01

On 19 October 2014 the comet Siding Spring flew by Mars. This was a unique opportunity to study the interaction between a cometary and a planetary magnetosphere. Here we model the magnetosphere of the comet using a hybrid plasma solver (ions as particles, electrons as a fluid). The undisturbed upstream solar wind ion conditions are estimated from observations by ASPERA-3/IMA on Mars Express during several orbits. It is found that Mars probably passed through a solar wind that was disturbed by the comet during the flyby. The uncertainty derives from that the size of the disturbed solar wind region in the comet simulation is sensitive to the assumed upstream solar wind conditions, especially the solar wind proton density.

Global solar wind variations over the last four centuries

PubMed Central

Owens, M. J.; Lockwood, M.; Riley, P.

2017-01-01

The most recent “grand minimum” of solar activity, the Maunder minimum (MM, 1650–1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth’s magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima. PMID:28139769

Convective and radiative components of wind chill in sheep: Estimation from meteorological records

NASA Astrophysics Data System (ADS)

Brown, D.; Mount, L. E.

1987-06-01

Wind chill is defined as the excess of sensible heat loss over what would occur at zero wind speed with other conditions unchanged. Wind chill can be broken down into a part that is determined by air temperature and a radiative part that comprises wind-dependent effects on additional long-wave radiative exchange and on solar radiation (by reducing solar warming). Radiative exchange and gain from solar radiation are affected by changes that are produced by wind in both surface and fleece insulations. Coefficients are derived for (a) converting the components of sensible heat exchange (air-temperature-dependent including both convective and associated long-wave radiative, additional long-wave radiative and solar) into the components of the total heat loss that are associated with wind and (b) for calculating equivalent air temperature changes. The coefficients contain terms only in wind speed, wetting of the fleece and fleece depth; these determine the external insulation. Calculation from standard meteorological records, using Plymouth and Aberdeen in 1973 as examples, indicate that in April September 1973 at Plymouth reduction in effective solar warming constituted 28% of the 24-h total wind chill, and 7% in the other months of the year combined; at Aberdeen the corresponding percentages were 25% and 6%. Mean hour-of-day estimates for the months of April and October showed that at midday reduction in solar warming due to wind rose to the order of half the air-temperature-dependent component of wind chill, with a much smaller effect in January. For about six hours at midday in July reduction in solar warming due to wind was similar in magnitude to the air-temperature-dependent component. It is concluded that realistic estimates of wind chill cannot be obtained unless the effect of solar radiation is taken into account. Failure to include solar radiation results not only in omitting solar warming but also in omitting the effects of wind in reducing that warming. The exchange of sensible (non-evaporative) heat loss between a homeothermic animal and its environment can be divided into two parts: one part is due to the temperature difference between the animal and the surrounding air, and the other part is due to additional long-wave radiative exchange between animal and environment and to solar radiation. Both parts of the heat exchange are determined in magnitude by the animal's thermal insulation, which is itself affected by windspeed and wetting. Wind diminishes as animal's external insulation, so increasing heat loss under all conditions when the air temperature is lower than the animal's surface temperature: this effect is termed wind chill. Wind chill has previously been investigated more commonly in relation to man (Burton an Edholm, 1955; Smithson and Baldwin, 1978; Mumford, 1979; Baldwin and Smithson, 1979). This paper is concerned with the separate contributions to wind chill calculated for sheep that can be associated with convective and radiative heat exchanges.

Radioactivites in returned lunar materials and in meteorites

NASA Technical Reports Server (NTRS)

Fireman, E. L.

1983-01-01

The cosmic-ray, solar-flare, and solar-wind bombardments of lunar rocks and soils and meteorites were studied by measurements of tritium, carbon-14 and argon radioactivity. The radioactivity integrates the bombardment for a time period equal to several half-lines. H-3, Ar-37, Ar-39, C-14. For the interior samples of lunar rocks and for deep lunar soil samples, the amounts of the radioactivities were equal to those calculated for galactic cosmic-ray interactions. The top near-surface samples of lunar rocks and the shallow lunar soil samples show excess amounts of the radioactivities attributable to solar flares. Lunar soil fines contain a large amount of hydrogen due to implanted solar wind. Studies of the H-3 in lunar soils and in recovered Surveyor-3 materials gave an upper limit for the H-3/H ratio in the solar wind of 10 to the -11th power. Solar wind carbon is also implanted on lunar soil fines. Lunar soils collected on the surface contained a 0.14 component attributable to implanted solar wind C-14. The C-14/H ratio attributed to the solar wind from this C-14 excess is approximately 4 x 10 to the -11th power.

Propagation of Interplanetary Disturbances in the Outer Heliosphere

NASA Technical Reports Server (NTRS)

Wang, Chi

2002-01-01

Work finished during 2002 included: (1) Finished a multi-fluid solar wind model; (2) Determined the solar wind slowdown and interstellar neutral density; (3) Studied shock propagation and evolution in the outer heliosphere; (4) Investigated statistical properties of the solar wind in the outer heliosphere.

Unintentional Insider Threats: A Review of Phishing and Malware Incidents

DTIC Science & Technology

2014-07-01

their agency as deliberate, malicious hackers [1]. This research supports the conclusions in the 2013 Verizon Data Breach Report that 47% of...References [1] SolarWinds. SolarWinds Federal Cybersecurity Survey Summary Report. SolarWinds, 2014. [2] Verizon. 2013 Data Breach Investigations

Dependence of Subsolar Magnetopause on Solar Wind Properties using the Magnetosphere Multiscale Mission

NASA Astrophysics Data System (ADS)

Russell, C. T.; Zhao, C.; Qi, Y.; Lai, H.; Strangeway, R. J.; Paterson, W. R.; Giles, B. L.; Baumjohann, W.; Torbert, R. B.; Burch, J.

2017-12-01

The nature of the solar wind interaction with the Earth's magnetic field depends on the balance between magnetic and plasma forces at the magnetopause. This balance is controlled by the magnetosonic Mach number of the bow shock standing in front of the magnetosphere. We have used measurements of the solar wind obtained in the near Earth solar wind to calculate this Mach number whenever MMS was near the magnetopause and in the subsolar region. In particular, we examine two intervals of magnetopause encounters when the solar wind Mach number was close to 2.0, one when the IMF was nearly due southward and one when it was due northward. The due southward magnetic field produced a rapidly oscillating boundary. The northward magnetic field produced a much more stable boundary but with a hot low density boundary layer between the magnetospheric and magnetosheath plasmas. These magnetopause crossings are quite different than those studied earlier under high solar wind Mach number conditions.