A5023810917- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Earthquake Detection and Analysis
- Geomagnetism and Paleomagnetism Studies
- Seismic Waves and Analysis
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Atmospheric Ozone and Climate
- Laser-induced spectroscopy and plasma
- earthquake and tectonic studies
- Underwater Acoustics Research
- Ocean Waves and Remote Sensing
- Tropical and Extratropical Cyclones Research
- Acoustic Wave Phenomena Research
- Planetary Science and Exploration
- Speech and Audio Processing
- Particle accelerators and beam dynamics
- Magnetic confinement fusion research
- Laser-Plasma Interactions and Diagnostics
- Geophysics and Sensor Technology
- Space Satellite Systems and Control
- Stellar, planetary, and galactic studies
- Gyrotron and Vacuum Electronics Research
- Oceanographic and Atmospheric Processes
Goddard Space Flight Center
2021-2024
Heliophysics
2022-2024
University of Minnesota System
2011-2023
Nagoya University
2023
Earth and Space Research
2023
University of Alberta
2023
University of Minnesota
2013-2022
Twin Cities Orthopedics
2011-2021
John Wiley & Sons (United States)
2019
Charles River Laboratories (Netherlands)
2019
Abstract From a survey of the first nightside season NASA's Van Allen Probes mission (December 2012 to September 2013), 47 energetic (tens hundreds keV) electron injection events were found at L shells ≤ 4, all which are deeper than any previously reported substorm‐related injections. Preliminary details from these presented, including how occurred shortly after dipolarization signatures and injections observed higher shells, deepest was ~ 2.5, and, surprisingly, 4 limited in energy ≤250...
Abstract We present observations that provide the strongest evidence yet discrete whistler mode chorus packets cause relativistic electron microbursts. On 20 January 2016 near 1944 UT low Earth orbiting CubeSat Focused Investigations of Relativistic Electron Bursts: Intensity, Range, and Dynamics (FIREBIRD II) observed energetic microbursts (near L = 5.6 MLT 10.5) from its lower limit 220 keV, to 1 MeV. In outer radiation belt magnetically conjugate, Van Allen Probe A rising‐tone, band waves...
[1] We present results of a study the characteristics very large amplitude whistler mode waves inside terrestrial magnetosphere at radial distances less than 15 RE using waveform capture data from Wind spacecraft. observed 247 with least one electric field component (105/247 had ≥80 mV/m peak-to-peak amplitudes) and 66 search coil magnetic (38/66 ≥0.8 nT amplitudes). Wave vectors determined events three components indicate that 30/46 propagate within 20° ambient field, though some are more...
Abstract We present the first quantified measure of energy dissipation rates, due to wave‐particle interactions, in transition region Earth's collisionless bow shock using data from Time History Events and Macroscale Interactions during Substorms spacecraft. Our results show that interactions can regulate global structure dominate shocks. In every crossing examined, we observed both low‐frequency (<10 Hz) high‐frequency ( 10 electromagnetic waves throughout entire into magnetosheath. The...
We present observations of electromagnetic precursor waves, identified as whistler mode at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All right‐hand polarized field (spacecraft frame), all but one vector in incidence frame. They have rest frame frequencies f ci < ≪ ce wave numbers 0.02 ≲ k ρ 5.0....
Abstract We identify electromagnetic field variations from the Van Allen Probes which have properties of Doppler shifted kinetic scale Alfvénic line resonances. These are observed during injections energetic plasmas into inner magnetosphere. waves sizes perpendicular to magnetic determined be order an ion gyro‐radius ( ρ i ) and less. Cross‐spectral analysis electric fields reveals phase transitions at frequencies correlated with enhancements depressions in ratio fields. Modeling shows that...
We present the first observations of large amplitude waves in a well-defined electron diffusion region at sub-solar magnetopause using data from one THEMIS satellite. These identified as whistler mode waves, electrostatic solitary lower hybrid and cyclotron are observed same 12-sec waveform capture association with signatures active magnetic reconnection. The coincident abrupt increases parallel temperature suggesting strong wave heating. which scale enable us to probe dynamics were analyzed...
Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations a injection into inner magnetosphere. In premidnight sector at
Abstract Poloidal ULF waves are capable of efficiently interacting with energetic particles in the ring current and radiation belt. Using Van Allen Probes (Radiation Belt Storm (RBSP)) data from October 2012 to July 2014, we investigate spatial distribution storm time occurrence Pc4 (7–25 mHz) poloidal inner magnetosphere. sorted into two categories: without significant magnetic compressional components. Two types have comparable rates, both which much higher during geomagnetic storms. The...
Abstract The impact of radial diffusion in storm time radiation belt dynamics is well‐debated. In this study we quantify the changes and variability coefficients during geomagnetic storms. A statistical analysis Van Allen Probes data (2012–2019) conducted to obtain measurements magnetic electric power spectral densities for Ultra Low Frequency (ULF) waves, corresponding coefficients. results show global wave enhancements occur main phase, continue into recovery phase. Local asymmetries...
[1] We present multi-satellite observations of large amplitude radiation belt whistler-mode waves and relativistic electron precipitation. On separate occasions during the Wind petal orbits STEREO phasing orbits, recorded intense in outer nightside equatorial with peak-to-peak amplitudes exceeding 300 mV/m. During these intervals wave activity, SAMPEX microbursts near magnetic conjunction STEREO. This evidence microburst precipitation occurring at same time nearly local L-shell a bursty...
Abstract We present a detailed outline and discussion of the analysis techniques used to compare relevance different energy dissipation mechanisms at collisionless shock waves. show that low‐frequency, quasi‐static fields contribute less ohmic dissipation, (− j · E ), than their high‐frequency counterparts. In fact, we found high‐frequency, large‐amplitude (>100 mV/m and/or >1 nT) waves are ubiquitous in transition region shocks. quantitatively fields, through wave‐particle...
Abstract Using the Helium Oxygen Proton Electron (HOPE) and Electric Field Waves (EFW) instruments from Van Allen Probes, we explored relationship between electron energy fluxes in eV keV ranges spacecraft surface charging. We present statistical results on charging within geosynchronous orbit by L MLT. An algorithm to extract H + line HOPE instrument data was developed better explore intense events. Also, this study how potential relates number density, pressure, temperature, thermal...
Abstract Short‐lived (<1 s) but intense electron precipitation, known as “microbursts,” may contribute significantly to losses in the outer radiation belt. Their origin has been suggested correlate with resonant scattering by whistler‐mode chorus waves, existing models cannot fully explain properties of microbursts, particular, bouncing packets form a microburst that have recently observed. A numerical model is presented reproduces series bounce response individual elements. Results...
Abstract Using the Parker Solar Probe FIELDS bandpass-filter data and SWEAP electron from Encounters 1 through 9, we show statistical properties of narrowband whistlers ∼16 R s to ∼130 , compare wave occurrence including beta, temperature anisotropy, heat flux. Whistlers are very rarely observed inside ∼28 (∼0.13 au). Outside 28 they occur within a narrow range parallel beta ∼1 10, with beta-heat flux consistent whistler fan instability. Because distributions ∼30 display signatures ambipolar...
We present waveform observations of electromagnetic lower hybrid and whistler waves with f_ci << f < f_ce downstream four supercritical interplanetary (IP) shocks using the Wind search coil magnetometer. The were observed to have a weak positive correlation between \partialB normalized heat flux magnitude an inverse T_eh/T_ec. All simultaneous electron distributions satisfying instability threshold most T_{perp,h}/T_{para,h} > 1.01. Thus, mode appear be driven by cause perpendicular heating...
Observation and model results accumulated in the last decade indicate that substorms can promptly inject relativistic ‘killer’ electrons (≥MeV) addition to 10–100 keV subrelativistic populations. Using measurements from Cluster, Polar, LANL, GOES satellites near midnight sector, we show two events intense electric fields, as large 20 mV/m, associated with substorm dipolarization are injections of into outer radiation belt. Enhancements hundreds at magnetotail account for injected MeV through...
Abstract Purely compressional electromagnetic waves (fast magnetosonic waves), generated at multiple harmonics of the local proton gyrofrequency, have been observed by various types satellite instruments (fluxgate and search coil magnetometers electric field sensors), but most recent studies used data from sensors, many restricted to high harmonics. We report here on a survey low‐harmonic waves, based magnetic Electric Fields Waves double probe Magnetic Field Instrument Suite Integrated...
Abstract With data from Van Allen Probes, we investigate electromagnetic ion cyclotron (EMIC) wave excitation using simultaneously observed distributions. Strong He band waves occurred while the spacecraft was moving through an enhanced density region. We extract helium, oxygen, proton, and electron mass spectrometer measurement velocity distributions of warm heavy ions as well anisotropic energetic protons that drive growth instability. Fitting measured fluxes to multiple sin m ‐type...
Abstract The Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) mission of opportunity working in tandem with the Van Allen Probes was designed to study loss radiation electrons ionosphere and upper atmosphere. BARREL is also sensitive X‐rays from other sources. During second campaign, Sun produced an X‐class flare followed by a solar energetic particle event (SEP) associated same active region. Two days later on 9 January 2014, shock generated coronal mass ejection (CME)...
Abstract Using the Van Allen Probes, we investigate enhancement in large‐scale duskward convection electric field during geomagnetic storm ( Dst ~ −120 nT) on 1 June 2013 and its role ring current ion transport energization plasmasphere erosion. During this storm, enhancements of ~1–2 mV/m corotating frame are observed down to L shells as low ~2.3. A simple model consisting a dipole magnetic constant, azimuthally westward, is used calculate earthward westward drift 90° pitch angle ions. This...
Abstract The magnetospheric driver of strong thermal emission velocity enhancement (STEVE) is investigated using conjugate observations when Van Allen Probes' footprint directly crossed both STEVE and stable red aurora (SAR) arc. In the ionosphere, associated with subauroral ion drift features, including electron temperature peak, density gradient, westward flow. SAR arc at lower latitudes corresponds to regions inside plasmapause isotropic plasma heating, which causes redline‐only via heat...
Abstract We present the first statistical analysis with continuous data coverage and nonaveraged amplitudes of prevalence distribution high‐amplitude (>5 mV/m) whistler mode waves in outer radiation belt using 5 years Van Allen Probes data. These are most common above L = 3.5 between magnetic local time 0–7 where they 1–4% time. During high geomagnetic activity, wave occurrence rises 30% some regions. these active times plasmasphere erodes to lower observed at all outside it, highest low...