A5010225205- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Earthquake Detection and Analysis
- Planetary Science and Exploration
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Stellar, planetary, and galactic studies
- Seismic Waves and Analysis
- Solar Radiation and Photovoltaics
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Spacecraft Design and Technology
- Dust and Plasma Wave Phenomena
- Lightning and Electromagnetic Phenomena
- Ocean Waves and Remote Sensing
- Geophysics and Sensor Technology
- Magnetic Field Sensors Techniques
- Atomic and Subatomic Physics Research
- Spacecraft and Cryogenic Technologies
- Radio Astronomy Observations and Technology
- Atmospheric Ozone and Climate
- earthquake and tectonic studies
University of California, Berkeley
2016-2025
University of California System
2008-2024
University of Michigan–Ann Arbor
2021
1366 Technologies (United States)
2021
Berkeley College
2020
University of Colorado Boulder
2020
Utah State University
2020
SRI International
2020
University of Southern California
2020
University of California, Los Angeles
2020
We report THEMIS observations of a dipolarization front, sharp, large‐amplitude increase in the Z ‐component magnetic field. The front was detected central plasma sheet sequentially at X = −20.1 R E (THEMIS P1 probe), −16.7 (P2), and −11.0 (P3/P4 pair), suggesting its earthward propagation as coherent structure over distance more than 10 velocity 300 km/s. thickness found to be small ion inertial length. Comparison with simulations allows us interpret leading edge fast flow formed by burst...
The Electric Fields and Waves (EFW) Instruments on the two Radiation Belt Storm Probe (RBSP) spacecraft (recently renamed Van Allen Probes) are designed to measure three dimensional quasi-static low frequency electric fields waves associated with major mechanisms responsible for acceleration of energetic charged particles in inner magnetosphere Earth. For this measurement, instrument uses pairs spherical double probe sensors at ends orthogonal centripetally deployed booms spin plane...
[1] We discuss results of a superposed epoch analysis dipolarization fronts, rapid (δt 10 nT) increases in the northward magnetic field component, observed during six Time History Events and Macroscale Interactions Substorms (THEMIS) conjunction events. All fronts propagated earthward; time delays at multiple probes were used to determine their propagation velocity. We define typical electric plasma parameter variations front crossings estimate characteristic gradient scales. The study...
Pulsating aurora, a spectacular emission that appears as blinking of the upper atmosphere in polar regions, is known to be excited by modulated, downward-streaming electrons. Despite its distinctive feature, identifying driver electron precipitation has been long-standing problem. Using coordinated satellite and ground-based all-sky imager observations from THEMIS mission, we provide direct evidence naturally occurring electromagnetic wave, lower-band chorus, can drive pulsating aurora....
The first two orbits of the Parker Solar Probe (PSP) spacecraft have enabled in situ measurements solar wind down to a heliocentric distance 0.17 au (or 36 Rs). Here, we present an analysis this data study turbulence at and its evolution out 1 au. While many features remain similar, key differences include: increased energy levels by more than order magnitude, magnetic field spectral index -3/2 matching that velocity both Elsasser fields, lower compressibility consistent with smaller...
One of the most striking observations made by Parker Solar Probe during its first solar encounter is omnipresence rapid polarity reversals in a magnetic field that otherwise mostly radial. These so-called switchbacks strongly affect dynamics field. We concentrate here on their macroscopic properties. First, we find these structures are self-similar, and have neither characteristic magnitude, nor duration. Their waiting time statistics shows evidence for aggregation. The associated long...
Observations of three closely‐spaced THEMIS spacecraft at 9–11 Re near midnight and close to the neutral sheet are used investigate a sharp injection/dipolarization front (SDF) propagating inward in flow‐braking region. This SDF was very thin current along North‐South direction embedded within an Earthward‐propagating flow burst. A short‐lived depression total magnetic field (down 1 nT), devoid wave activity intense particle fluxes, stays ahead SDF. Clear finite proton gyroradius effects,...
A long-standing problem in the field of space physics has been origin plasmaspheric hiss, a naturally occurring electromagnetic wave high-density plasmasphere (roughly within 20,000 kilometers Earth) that is known to remove high-energy Van Allen Belt electrons pose threat satellites and astronauts. recent theory tied hiss seemingly different outer magnetosphere, but this was difficult test because challenging set observational requirements. Here we report on experimental verification theory,...
The FAST spacecraft observes Alfvénic fluctuations in field quantities throughout the auroral oval. In this report, we show preliminary results from a statistical study of Alfvén waves with transverse scales comparable to electron skin‐depth observed over frequency range 0.2 ∼20 Hz frame. This shows that these are most commonly found magnetospheric cusps and at polar cap boundary oval premidnight sector where intense events observed. It is shown wave Poynting flux well correlated energy...
A statistical survey of plasma densities and electron distributions (0.5–100 keV) is performed using data obtained from the Time History Events Macroscale Interactions During Substorms spacecraft in near‐equatorial orbits 1 July 2007 to May 2009 order investigate optimum conditions for whistler mode chorus excitation. The density calculated potential, together with situ magnetic field, used construct global maps cyclotron Landau resonant energies under quiet, moderate, active geomagnetic...
Following a long interval (many days) of sustained very quiet geomagnetic conditions, electromagnetic ion cyclotron (EMIC) wave activity was seen by the CARISMA array (www.carisma.ca) on ground for several hours simultaneously with enhanced solar wind density and related magnetic compression at GOES 12 29th June 2007. The THEMIS C, D, E satellites were outbound in “string‐of‐pearls” configuration each observed EMIC waves L‐shells ranging from 5 to 6.5. resolved some spatial‐temporal...
Drift‐resonance wave‐particle interaction is a fundamental collisionless plasma process studied extensively in theory. Using cross‐spectral analysis of electric field, magnetic and ion flux data from the Van Allen Probe (Radiation Belt Storm Probes) spacecraft, we present direct evidence identifying generation mode standing poloidal wave through drift‐resonance interactions inner magnetosphere. Intense azimuthal field (E φ ) oscillations as large 10mV/m are observed, associated with radial...
Recent reports of large‐amplitude whistler waves (>100 mV/m) in the radiation belts have intensified interest role accelerating belt electrons to MeV energies. Several critical parameters for addressing this issue not previously been observed, including occurrence frequency, spatial extent and longevity regions whistlers. The THEMIS mission, with multiple satellites a near‐equatorial orbit, offers an excellent opportunity study these waves. We use data from Electric Field Instrument (EFI)...
Statistical results on the global distribution of suprathermal electron (0.1–10 keV) fluxes are shown both outside and inside plasmasphere separately, using data from THEMIS. Significant found within plasmasphere, although they nevertheless smaller than populations plasmasphere. Electron plasmapause increase with stronger magnetic activity nightside decrease as a function increasing local time (MLT). Inside just plasmapause, particularly midnight to dawn sector during active times, while...
Heat transport in the solar corona and wind is still a major unsolved astrophysical problem. Because of key role played by electrons, electron density temperature(s) are important prerequisites for understanding these plasmas. We present such situ measurements along two first encounters Parker Solar Probe (PSP), between 0.5 0.17 AU from Sun, revealing different states emerging near activity minimum. These preliminary results obtained simplified analysis plasma quasi-thermal noise (QTN)...
Abstract Chorus waves are among the most important natural electromagnetic emissions in magnetosphere as regards to their potential effects on electron dynamics. They can efficiently accelerate or precipitate electrons trapped outer radiation belt, producing either fast increases of relativistic particle fluxes auroras at high latitudes. Accurately modeling effects, however, requires detailed models wave power and obliquity distribution a function geomagnetic activity particularly wide...
Abstract Electromagnetic ion cyclotron (EMIC) waves have been suggested to be a cause of radiation belt electron loss the atmosphere. Here simultaneous, magnetically conjugate measurements are presented EMIC wave activity, measured at geosynchronous orbit and on ground, energetic precipitation, seen by Balloon Array for Radiation Relativistic Electron Losses (BARREL) campaign, two consecutive days in January 2013. Multiple bursts precipitation were observed duskside magnetosphere end 18...
[1] Chorus waves, which have received intense attention recently due to their significant role in radiation belt electron dynamics, frequently exhibit rising and falling tones. Lower-band chorus observed using THEMIS wave burst data, are analyzed obtain the typical properties of either class emissions. Our results show that tones more likely be quasi field-aligned, whereas typically very oblique, close resonance cone. Furthermore, occur significantly often than tones, magnetic amplitudes...
The characteristics of the Poynting flux and wave normal vectors whistler‐mode waves outside plasmapause are investigated for lower (0.1–0.5 f ce ) upper bands (0.5–0.8 ), where is equatorial electron cyclotron frequency. To analyze properties, we utilized high‐resolution waveform data from multiple THEMIS spacecraft in near‐equatorial magnetosphere June 2008 to November 2012. Full measurements electric magnetic fields used calculate fluxes construct vectors, which then polar azimuthal...