A5010913227- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Earthquake Detection and Analysis
- GNSS positioning and interference
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Lightning and Electromagnetic Phenomena
- Nuclear physics research studies
- Laser-induced spectroscopy and plasma
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Nuclear Physics and Applications
- Planetary Science and Exploration
- Atmospheric Ozone and Climate
- Spacecraft Design and Technology
- Atomic and Molecular Physics
- Astronomical and nuclear sciences
- Seismic Waves and Analysis
- Dust and Plasma Wave Phenomena
- Quantum Chromodynamics and Particle Interactions
- Space Satellite Systems and Control
- Magnetic Field Sensors Techniques
- Atomic and Subatomic Physics Research
- Spacecraft and Cryogenic Technologies
Goddard Space Flight Center
2015-2025
Heliophysics
2008-2024
Heliophysics Science Division
2011-2023
University of California, Los Angeles
2023
High Altitude Observatory
2023
University of Colorado Boulder
2023
NSF National Center for Atmospheric Research
2023
National Aeronautics and Space Administration
2008-2019
Charles River Laboratories (Netherlands)
2016
Kiel University
2008
The Electric and Magnetic Field Instrument Integrated Science (EMFISIS) investigation on the NASA Radiation Belt Storm Probes (now named Van Allen Probes) mission provides key wave very low frequency magnetic field measurements to understand radiation belt acceleration, loss, transport. science objectives contribution that EMFISIS makes providing as well theory modeling are described. components of instruments suite, both electronics sensors, including functional parameters, calibration,...
We report observations of “fast solitary waves” that are ubiquitous in downward current regions the mid‐altitude auroral zone. The single‐period structures have large amplitudes (up to 2.5 V/m), travel much faster than ion acoustic speed, carry substantial potentials ∼100 Volts), and associated with strong modulations energetic electron fluxes. amplitude speed distinguishes them from ion‐acoustic waves or weak double layers. electromagnetic signature appears be an positive charge (electron...
Observations of plasma particles and fields by the FAST satellite find evidence acceleration intense upgoing electron beams quasi‐static parallel electric fields. The beam characteristics include a broad energy spectrum with peak energies between 100 eV 5 keV, perpendicular temperatures less than 1 eV, fluxes greater 10 9 /cm²sec. Diverging electrostatic shocks associated have integrated potentials that match energy. These are found in regions downward Birkeland current account for total...
The FAST satellite mission investigates plasma processes occurring in the low altitude auroral acceleration region, where magnetic field‐aligned currents couple global magnetospheric current systems to high latitude ionosphere. In transition region between hot tenuous and cold, dense ionosphere, these give rise parallel electric fields, particle beams, heating, a host of wave‐particle interactions. instruments provide observations particles fields this with excellent temporal spatial...
Electric field and energetic particle observations by the Fast Auroral Snapshot (FAST) satellite provide convincing evidence of acceleration quasi‐static, magnetic‐field‐aligned (parallel) electric fields in both upward downward current regions auroral zone. We demonstrate this comparing inferred parallel potentials electrostatic shocks with energies. also report nonlinear structures which may play a role supporting fields. These include large‐amplitude ion cyclotron waves region, intense,...
Characteristics of solitary waves observed by Polar in the high altitude cusp, polar cap and plasma sheet boundary are reported compared to observations auroral zone. The study presented herein shows that, at altitudes, positive potential structures (electron holes), with scale sizes order 10's Debye lengths, which usually propagate velocities a few thousand km/s. At boundary, direction propagation can be either upward or downward; whereas leading edge cusp energetic particle injections, it...
The Fast Auroral SnapshoT (FAST) satellite has made observations in the Kilometric Radiation (AKR) source region with unprecedented frequency and time resolution. We confirm AKR is a density depleted cavity present examples which cold electrons appeared to have been nearly evacuated ( n hot > ). Electron distributions were at low‐energies up‐going ion beams always present. Source amplitudes far greater than previously reported, reaching 2×10 −4 (V/m)²/Hz (300 mV/m) short bursts bandwidths...
We have measured the longitudinal momentum distribution of ${}^{18}\mathrm{C}$, ${}^{17}\mathrm{C}$, and ${}^{16}\mathrm{C}$ after one-neutron breakup $^{19}C$, respectively, using A1200 fragment separator as an energy-loss spectrometer. The observed narrow width $44.3\ifmmode\pm\else\textpm\fi{}5.9\mathrm{MeV}/c$ for ${}^{18}\mathrm{C}$ fragments indicates that ${}^{19}\mathrm{C}$ is a new example halo, so far heaviest ever observed. consequences obtained results on structure three isotopes...
The three-body decay $^{12}\mathrm{O}\ensuremath{\rightarrow}2p+^{10}\mathrm{C}$ was studied following production via single-neutron stripping from a radioactive $^{13}\mathrm{O}$ projectile. This is the first observation of two-proton emission an unbound ground state where one-proton channel energetically closed beyond lightest case $^{6}\mathrm{Be}$. No evidence for $^{2}\mathrm{He}$ seen, despite predictions large diproton branching ratio. An upper limit 7% (95% C.L.) established this...
The first simultaneous electric field observations performed in the ionosphere and atmosphere over an active nighttime thunderstorm are reported here. In stratosphere, typical storm‐related dc fields were detected from a horizontal distance of ∼100 km, transient due to lightning measured at several different altitudes. mesosphere, lightning‐induced range tens millivolts per meter with rise times least as fast 0.2 ms duration 10–20 ms. transients had significant components parallel magnetic...
During the PLUMEX I rocket flight from Kwajalein Island, plasma density and electric field fluctuations were measured in situ, simultaneous with ground‐based radar backscatter measurements at 0.96‐m 0.36‐m wavelengths. The penetrated an extremely turbulent topside region which had associated intense backscatter. As by power was decaying time during after flight. intermediate wavelength (0.1–10 km) situ electron are described a companion paper, while here we report transitional short results...
[1] An unexpected feature revealed by the measurements of Communication/Navigation Outage Forecasting System (C/NOFS) satellite is presence broad plasma depletions in midnight–dawn sector during deep solar minimum. It has not been well understood what causes and how equatorial bubbles are related to depletions. In this paper we present C/NOFS a few cases. The ion density perturbations enhanced vertical velocity first identified topside F region at ∼2200 LT, suggesting that start form earlier...
Abstract We present a statistical survey of the latitudinal structure fast magnetosonic wave mode detected by Van Allen Probes spanning time interval 21 September 2012 to 1 August 2014. show that statistically, occurrence frequency ( f ) normalized local proton cyclotron cP has distinct funnel‐shaped appearance in latitude about magnetic equator similar found case studies. By comparing observed E/B ratios with model ratio, using plasma density and background field magnitude as input we this...
Abstract. The lower-thermosphere–ionosphere (LTI) system consists of the upper atmosphere and lower part ionosphere as such comprises a complex coupled to both below space above. atmospheric LTI is dominated by laws continuum fluid dynamics chemistry, while plasma controlled electromagnetic forces driven magnetosphere, solar wind, well wind dynamo. hence domain many different physical processes. However, systematic in situ measurements within this region are severely lacking, although...
The lower thermosphere-ionosphere (LTI) is a key transition region between Earth’s atmosphere and space. Interactions ions neutrals maximize within the LTI in particular at altitudes from 100 to 200 km, which least visited of near-Earth environment. lack situ co-temporal co-spatial measurements all relevant parameters their elusiveness most remote-sensing methods means that complex interactions its neutral charged constituents remain poorly characterized this date. This measurements,...
Small‐scale solitary electric potential structures are commonly observed on auroral field lines with the Polar Electric Field Instrument (EFI). This study focuses observations of in southern hemisphere zone at altitudes between 5500 and 7500 km. Some similar to those previously by S3‐3 Viking satellites inferred be negative pulses traveling upward along magnetic lines, associated upgoing ion beams currents. The velocities these “ion” estimated, using spaced EFI measurements, distributed...
The Fast Auroral SnapshoT (FAST) explorer frequently observes the auroral density cavity, which is source region for Kilometric Radiation (AKR). An important factor in generation of AKR relative abundance hot and cold electrons within since introduce relativistic modifications to wave dispersion. VLF wave‐form data acquired by FAST cavity show clear signatures whistler‐mode waves propagating on resonance cone. This allows us obtain electron plasma frequency, often has densities <1 cm −3 ....
Electric field and plasma density instrumentation on board a sounding rocket launched from Punta Lobos, Peru, detected intense electrostatic waves indicative of instabilities in the daytime equatorial electrojet. Simultaneous measurements taken by Jicamarca radar showed strong 3‐m type 1 electrojet echoes as well evidence kilometer scale horizontally propagating waves. The situ electric wave spectra displayed three markedly different height regions within unstable layer: (1) two‐stream...
Intense electrostatic waves in the auroral E region have been detected simultaneously on two payloads launched a mother‐daughter configuration from Kiruna, Sweden. The data sets comprise electric field and density measurements ambient (dc) conditions to fluctuations as high 50 kHz. dc measured by both was 54 mV/m northwest, which corresponded an electron drift velocity of 1080 m/s. This drove two‐stream perpendicular B observed spacecraft throughout altitude agrees quite well with range...
The Communication/Navigation Outage Forecasting System (C/NOFS) satellite was launched in 2008, during solar minimum conditions. An unexpected feature the C/NOFS plasma density data is presence of deep depletions observed at sunrise all altitudes. Ionospheric irregularities are often embedded within these dawn depletions. Their frequencies strongly depend on longitude and season. Dawn also coincident passes such as DMSP CHAMP. In one example depletion extended 50° × 14° N‐S E‐W directions,...
DC electric fields and associated E × B plasma drifts detected with the double‐probe experiment on C/NOFS satellite during extreme solar minimum conditions near June 2008 solstice are shown to be highly variable, weak moderate ambient amplitudes of ∼1–2 mV/m (∼25–50 m/s). Average field or drift patterns show similarities those reported for more active conditions, i.e., eastward outward day westward inward at night. However, these vary significantly longitude not always present. Daytime...