A5066058076- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Earthquake Detection and Analysis
- Solar Radiation and Photovoltaics
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Astrophysics and Cosmic Phenomena
- Atmospheric Ozone and Climate
- Planetary Science and Exploration
- Magnetic confinement fusion research
- Global Energy and Sustainability Research
- Gamma-ray bursts and supernovae
- Dust and Plasma Wave Phenomena
- Photovoltaic System Optimization Techniques
- Market Dynamics and Volatility
- Space Exploration and Technology
- Electromagnetic Launch and Propulsion Technology
- High-pressure geophysics and materials
- Laser-Plasma Interactions and Diagnostics
- Ocean Waves and Remote Sensing
- Neural Networks and Applications
- Spacecraft Design and Technology
- GNSS positioning and interference
Laboratory for Atmospheric and Space Physics
2006-2017
University of Colorado Boulder
2006-2016
Los Alamos National Laboratory
1998-2011
University of Colorado System
2007-2011
University of California, San Diego
2010
University of Iowa
2010
Southwest Research Institute
2005-2009
University College London
2005
Observatoire Midi-Pyrénées
2005
Jet Propulsion Laboratory
2005
Many years of research have demonstrated that large, nonrecurrent geomagnetic storms, shock wave disturbances in the solar wind, and energetic particle events interplanetary space often occur close association with large flares. This result has led to a paradigm cause effect ‐ flares are fundamental these near‐Earth environment. paradigm, which I call “the flare myth,” dominates popular perception relationship between activity provided much pragmatic rationale for study phenomenon. Yet there...
Eleven passes of the ISEE satellites through frontside terrestrial magnetopause (local time 0900–1700; GSM latitude 2–43°N) have been identified, where plasma velocity in and boundary layer was substantially larger than it magnetosheath. This paper examines nature flow, magnetic field, energetic particle fluxes these regions, with a view to determining whether enhancements can be explained by magnetic‐field reconnection. The principal question is observed difference tangential Δv between...
Normally the ≳ 80‐eV electrons which carry solar wind electron heat flux are collimated along interplanetary magnetic field (IMF) in direction pointing outward away from sun. Occasionally, however, fluxes of observed traveling both parallel and antiparallel to IMF. Here we present results a survey such bidirectional events as with plasma experiments aboard ISEE 3 at times when spacecraft was not magnetically connected earth's bow shock. The onset usually signals entry into distinct entity,...
This study examines solar wind plasma and magnetic field observations from Ulysses' first full polar orbit in order to characterize the high‐latitude under conditions of decreasing low activity. By comparing taken over nearly all heliolatitudes two different intervals covering same radial distances, we are able separate latitudinal variations wind. We find that once gradients removed, none parameters show much variation, indicating emanating coronal holes is extremely uniform. In addition,...
Observations of solar wind from both large polar coronal holes (PCHs) during Ulysses' third orbit showed that the fast was slightly slower, significantly less dense, cooler, and had mass momentum flux than previous minimum (first) orbit. In addition, while much more variable, measurements in in‐ecliptic match quantitatively with Ulysses show essentially identical trends. Thus, these combined observations indicate significant, long‐term variations output entire Sun. The trend to lower dynamic...
A survey of two‐dimensional electron velocity distributions, ƒ( V ), measured near the earth's bow shock using Los Alamos/Garching plasma instrumentation aboard ISEE 2 is presented. This provides clues to mechanisms thermalization within and relaxation both upstream downstream distributions. First, foreshock boundary, fluxes electrons having a power law shape at high energies backstream from shock. Although most often they appear as monotonically decreasing extension solar wind distributions...
Ion velocity space distributions measured with Los Alamos/Garching instruments on ISEE 1 and 2 across the earth's bow shock have revealed that nearly perpendicular reflects some fraction of incident solar wind ions over a wide range Mach numbers ( M A ≃ 2.0–12.4). The relative density reflected varies from 1–3% at to 15–25% = 8–12, in qualitative agreement computer simulations predictions indicate such are needed provide essential dissipation shock. These gyrate about B plasma rest frame...
We have obtained direct evidence for local magnetic reconnection in the solar wind using plasma and field data by Advanced Composition Explorer (ACE). The prime consists of accelerated ion flow observed within reversal regions wind. Here we report such observations interior an interplanetary coronal mass ejection (ICME) or at interface between two ICMEs on 23 November 1997 a time when was stronger than usual. acceleration consistent with Walen relationship, which relates changes velocity to...
Observations upstream of the earth's bow shock with LASL/MPI fast plasma experiments on ISEE 1 and 2 reveal presence two distinct mutually exclusive populations low energy (≤ 40 keV) ions apparently accelerated at shock. The first these, "reflected" population, is characterized by 1) sharply peaked spectra seldom extending much above ∼ 10 keV/ion 2) relatively collimated flow coming from direction On other hand, "diffuse" are distinguished flat keV broad angular distributions. They far most...
Measurements with Los Alamos Scientific Laboratory instrumentation aboard Imp 6, 7, and 8 reveal that approximately one third of all high‐speed solar wind streams observed at 1 AU contain a sharp boundary (of thickness less than ∼4 × 10 4 km) near their leading edge, called stream interface, which separates plasma distinctly different properties origins. Identified as discontinuities across the density drops abruptly, proton temperature increases speed rises, interfaces are remarkably...
Recent studies have shown that most Earthward transport hi the midtail, high‐beta plasma sheet takes place in form of short‐lived, high‐speed flow bursts. Bursty bulk flows are observed both when is thin, such as during substorm expansion, and it thick, recovery. We present multi‐instrument observations from ISEE1 ISEE 2 spacecraft to argue becomes thick close its equilibrium state, magnetic field signatures events consistent with theoretically predicted plasma‐depleted flux tubes or...
We present Ulysses solar wind plasma data from the peak southerly latitude of −80.2° on 12 September 1994 through corresponding northerly 31 July 1995. encountered fast throughout this time except for a 43° band centered equator. Median mass flux was nearly constant with latitude, while speed and density had positive negative poleward gradients, respectively. Solar momentum highest at high latitudes, suggesting latitudinal asymmetry in heliopause cross section. energy also latitudes.
Ulysses is now completing its second solar polar orbit, dropping back down in latitude as the Sun passes through post‐maximum phase of cycle. A mid‐sized circumpolar coronal hole that formed around maximum northern hemisphere has persisted and produced a highly inclined CIR, which was observed from ∼70°N to ∼30°N. We find speed maxima high‐speed streams follow same slow drop with decreasing large holes minimum. These results suggest wind acceleration effect related heliolatitude or rotation....
During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of complex mixture water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties ion composition. Protons are the dominant species outside about 9 RS (where is radial distance from center Saturn), whereas inside, consists corotating comet-like mix ions with approximately 3% N+. Over A B rings, found an ionosphere which O2+ O+...
We have investigated solar wind flow properties associated with very low helium to hydrogen abundance ratios ( A (He)) observed Los Alamos instrumentation on IMP 6, 7, and 8 during the 1971 ‐ 1978 interval. characteristic pattern has been discovered, consisting of correlated interplanetary field reversals, high plasma density, nearly identical H + He ++ bulk velocities, kinetic temperatures minimums in their ratio. superposed epoch analysis 74 well defined sector boundary crossings 1971–1978...
Measurements made with the Fast Plasma Experiment on ISEE 2 in vicinity of high‐latitude, dusk magnetopause near terminator plane, at a time when local magnetosheath and tail lobe magnetic fields were nearly oppositely directed, provide direct evidence for reconnection open field lines lobes interplanetary (IMF). The consists primarily observations accelerated plasma flowing both tailward sunward within high‐latitude current layer. Observed speed changes order twice Alfven quantitatively...
The IMPACT (In situ Measurements of Particles And CME Transients) investigation on the STEREO mission was designed and developed to provide multipoint solar wind suprathermal electron, interplanetary magnetic field, energetic particle information required unravel nature coronal mass ejections their heliospheric consequences. consists seven individual sensors which are packaged into a boom suite, SEP suite. This review summarizes science objectives IMPACT, instruments that comprise...
Examination of solar wind plasma data obtained by the Los Alamos experiments on Imp 6, 7, and 8 during 1971–1978 interval has revealed a frequent association between minimums in helium abundance maximums proton density. These events occur at low flow speeds are strongly correlated with polarity reversals interplanetary magnetic field. A large fraction these high density‐low examples noncompressive density enhancements (NCDE), i.e., positive signals not readily associated stream‐stream...
Using plasma electron and magnetic field measurements from ISEE 3, 220 R E earth, we find that the magnetotail at distance is a coherent structure evidently waves about through distances comparable to its own lateral scale size. For one‐third of time it was inside magnetotail, 3 in sheet. During quiet times sheet apparently quite thin, but response geomagnetic activity expands, becoming filled with hot flowing tailward speeds sometimes exceeding 1000 km/sec, forces cross‐section itself...
Measurements of suprathermal electron fluxes in the solar wind indicate that field lines within coronal mass ejections, CMEs, near and beyond 1 AU are normally connected to Sun at both ends. However, on occasion some embedded deep CMEs appear be only one end. Here we propose an explanation for how such arise terms 3‐dimensional reconnection close Sun. Such also provides a natural flux rope topology characteristic many as well loops formed during long‐duration, soft X‐ray events. Our...
After ten long years of wandering the uncharted seas, Ulysses returned to his home port Ithaca. Similarly, after its unprecedented five year odyssey through previously regions over poles Sun, spacecraft has slow, variable solar wind which dominates observations near ecliptic plane. Solar plasma and magnetic field from are used examine this return fast polar region variability into a slow low latitude streamer belt. As it journeyed equatorward, encountered large corotating interaction...
Data from the Los Alamos Scientific Laboratory/Max‐Planck‐Institut fast plasma experiment on Isee 2 have been combined with data European Space Agency/Imperial College/Space Research Laboratory low‐energy proton 3 to obtain for first time an ion velocity distribution function f (ν) extending solar wind energies (∼1 keV) 1.6 MeV during postshock phase of energetic storm particle (ESP) event. This study reveals that ESP population is roughly isotropic in frame thermal out MeV. Emerging...