A5065251959- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Earthquake Detection and Analysis
- Geomagnetism and Paleomagnetism Studies
- Magnetic confinement fusion research
- Astro and Planetary Science
- Aerodynamics and Fluid Dynamics Research
- Fluid Dynamics and Turbulent Flows
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Lightning and Electromagnetic Phenomena
- High voltage insulation and dielectric phenomena
- earthquake and tectonic studies
- Atomic and Subatomic Physics Research
- Dark Matter and Cosmic Phenomena
- Radiation Therapy and Dosimetry
- GNSS positioning and interference
- Gas Dynamics and Kinetic Theory
The Aerospace Corporation
2014-2025
Lockheed Martin (United States)
1998-2001
We use results of guiding‐center simulations ion transport to map phase space densities the stormtime proton ring current. model a storm as sequence substorm‐associated enhancements in convection electric field. Our pre‐storm distribution is an analytical solution steady‐state which quiet‐time radial diffusion balances charge exchange. This spectra at L ∼2‐4 reproduce many features found observed spectra. Using from during storms having main phases 3, 6, and 12 hr, we distributions...
This is an investigation of stormtime particle transport that leads to formation the ring current. Our method trace guiding‐center motion representative ions (having selected first adiabatic invariants µ) in response model substorm‐associated impulses convection electric field. We compare our simulation results qualitatively with existing analytically tractable idealizations (direct convective access and radial diffusion) order assess limits validity these approximations. For µ ≲ 10 MeV/G (...
An important question that is being increasingly studied across subdisciplines of Heliophysics “how do mesoscale phenomena contribute to the global response system?” This review paper focuses on this within two specific but interlinked regions in Near-Earth space: magnetotail’s transition region inner magnetosphere and ionosphere. There a concerted effort Geospace Environment Modeling (GEM) community understand degree which transport magnetotail contributes dynamics magnetic flux...
Abstract Geomagnetic storms transfer massive amounts of energy from the sun to geospace. Some that is dissipated in ionosphere as energetic particles precipitate and their atmosphere, creating aurora. We used Time History Events Macroscale Interactions during Substorms (THEMIS) mosaic all‐sky‐imagers across Canada Alaska measure amount flux deposited into via auroral precipitation 2013 March 17 storm. determined time‐dependent percent total contributed by meso‐scale (<500 km wide)...
We employ a three‐dimensional ring current model to trace the bounce‐averaged drift of singly charged ions during storm‐associated enhancements in convection electric field. Using simulation results, we map proton phase space density main and recovery phases storm accordance with conservation ƒ. from an initial quiescent distribution that is obtained by solving steady state transport equation (bounce‐averaged charge exchange balancing radial diffusion) observed plasma sheet spectra as outer...
To investigate the spatial and spectral structure of diffuse aurora during a model geomagnetic storm characterized by random impulses in cross‐magnetospheric convection electric field, we simulate bounce‐averaged drift motion precipitation plasma sheet electrons. Bounce‐averaged trajectories are computed from Hamiltonian formulation which have treated electrons as though they were undergoing strong pitch angle diffusion Dungey's magnetosphere (dipole field plus uniform southward B z ). Using...
Abstract We investigate the effects of different ionospheric conductance and electron loss models on ring current dynamics during large magnetic storm 5–7 April 2010 using magnetically electrically self‐consistent Rice Convection Model–Equilibrium (RCM‐E). The time‐varying RCM‐E proton distribution boundary conditions are specified a combination TWINS 1 2 ion temperature maps in situ THEMIS GOES spectral measurements plasma sheet. With strong pitch‐angle diffusion, simulated equatorial...
The ability to accurately model precipitating electron distributions is crucial for understanding magnetosphere-ionosphere-thermosphere coupling processes. We use the magnetically and electrically self-consistent Rice Convection Model-Equilibrium (RCM-E) of inner magnetosphere assess how well different loss models can account observed fluxes during large 10 August 2000 magnetic storm. strong pitch angle scattering rate produces excessive on morning dayside at geosynchronous orbit (GEO)...
Effects of scattering electrons from whistler chorus waves and ions due to field line curvature on diffuse precipitating particle fluxes ionospheric conductance during the large 17 March 2013 storm are examined using self-consistent Rice Convection Model Equilibrium (RCM-E) model. Electrons found dominate integrated energy flux, with ~21:00 magnetic local time (MLT) eastward ~11:00 MLT main phase. Simulated proton oxygen ion precipitation is sporadic localized, occurring where model lines...
Particle flux measurements by the Charge and Mass Magnetospheric Ion Composition Experiment/Magnetospheric Spectrometer (CAMMICE/MICS) Hydra instruments on NASA Polar satellite have been used to build empirical models of plasma environment at low energies in Earth's inner magnetosphere. These may be develop design test specifications for spacecraft surface materials, which are susceptible damage ions. The combination CAMMICE/MICS provides ion range 20 eV 200 keV as a function position For...
Abstract During geomagnetic storms and substorms, the magnetosphere ionosphere are strongly coupled by precipitating magnetospheric electrons from Earth's plasma sheet driven both ionospheric processes. Magnetospheric wave activity initiates electron precipitation, upper atmosphere further facilitate this process enhancing value of precipitated energy fluxes via connection two magnetically conjugate regions multiple atmospheric reflections. This paper focuses on resulting affiliated...
Abstract In addition to wave particle scattering in the magnetosphere, atmospheric backscatter of magnetospheric electrons is an important process that contributes formation precipitated region diffuse aurora. Two magnetically conjugate regions are involved a complex magnetosphere‐ionosphere (MI) and energy interplay. Based on synthesizing previous theoretical/modeling studies experimental evidence, we demonstrate need for improving quantification processes can affect inner electrodynamics,...
In this study we compare the proton pitch angle distributions (PADs) in ring current region ( L ∼ 3–4) obtained from Combined Release and Radiation Effects Satellite (CRRES) observations during large magnetic storm (minimum Dst = −170 nT) on August 19, 1991, with results of phase‐space mapping simulations which trace bounce‐averaged drift protons storm‐associated enhancements a model convection electric field. We map density ƒ according to Liouville's theorem except for attenuation by charge...
Using a guiding‐center simulation of plasmasheet electrons postulated to be in strong pitch angle diffusion, we compute drift trajectories from Hamiltonian formulation and map phase space densities the nightside neutral line Dungey's model magnetosphere (dipole field plus uniform southward B z ) according Liouville's theorem modified for exponential loss implicit diffusion hypothesis. From resulting distributions precipitating energy flux into auroral ionosphere as functions magnetic...
Recent measurements show that magnetospheric convection electric fields during the main phases of magnetic storms are much more complicated in spatial structure than have generally been used to model formation stormtime ring current. To investigate transport effects such realistic on charged particles, we map Assimilative Model Ionospheric Electrodynamics (AMIE) potential functions analytically with a simple field at selected times interest several from 1997–1998 and extremely large storm...
In order to understand the characteristics of quiet time inner plasma sheet protons, we use a modified version Magnetospheric Specification Model simulate bounce averaged electric and magnetic drift isotropic protons in an approximately self‐consistent field. Proton differential fluxes are assigned model boundary mimic mixed tail source consisting hot from distant cooler low latitude layer (LLBL). The is local dependent based on Geotail observations results finite width convection model. For...
We evaluate the relative importance of stormtime ring current electrons to protons by calculating energy content ratio for typical energies inferred from observations and simulations. analyze Explorer 45 measurements taken around minimum Dst (=−171 nT) 17 December 1971 storm. simulate electron proton during a hypothetical storm using drift‐loss From data analysis, we find that with ∼1–50 keV ∼10–200 contribute most corresponding particle content. both simulations, only ∼1% as much quiet...
We investigate effects of magnetic self‐consistency on ring current development by calculating equatorial particle transport in a model that feeds back the magnetospheric configuration. The intensity is computed solving force‐balance equation plane. This computation coupled to kinetic proton and electron drift‐loss model. electric field used includes corotation, quiescent Volland‐Stern convection, storm‐associated enhancements convection. have modeled 19 October 1998 storm (min Dst = −112...
Significant increases in electron fluxes and energy densities at energies from 200 eV to ≥1 MeV have been observed during magnetic storms L values as low 2. To investigate the processes responsible for these flux of ring current electrons, we simulate guiding‐center drift loss electrons plasma sheet inner magnetosphere storms. We use a dipole field plus constant southward interplanetary our model. Over this model impose corotation, quiescent Stern‐Volland, storm‐associated enhancements...
We seek to determine whether the adiabatic plasma transport and energization resulting from electric magnetic drift can quantitatively account for sheet under weak enhanced convection observed by Geotail presented in companion paper [ Wang et al. , 2004 ]. use a modified Magnetospheric Specification Model simulate dynamics distributions of protons originating deep tail low‐latitude boundary layer (LLBL) an assigned, slowly increasing field. The field is Tsyganenko 96 model, so that force...
In order to understand the evolution of protons and magnetic field in inner plasma sheet from quiet disturbed conditions, we incorporate a modified version Magnetospheric Specification Model (MSM) with Tsyganenko 96 (T96) model simulate under an increasing convection electric two‐dimensional (2‐D) force balance maintained along midnight meridian. The local time dependent proton differential fluxes assigned boundary are mixture hot mantle cooler low latitude layer (LLBL). We previously used...
Abstract Ions in the plasma sheet are measured by energetic neutral atom imagers on Two Wide‐Angle Imaging Neutral‐Atom Spectrometers (TWINS) spacecraft. A line of sight (LOS) projection is used to determine location ions that dominate spectrum, assuming equatorial plane hottest region along LOS. We verify reasonable agreement between ion spectral shapes using this remote measurement technique and situ measurements from Time History Events Macroscale Interactions during Substorms (THEMIS)...
Internal charging has been indicated as the cause of many satellite anomalies. In some cases, it argued that internal caused system failures. It may be possible to predict occurrence an threat in future but does not remove necessity know what environmental be. The existence, for years now, energetic electron and measurements inner magnetosphere provides ability identify levels generate specifications. specifications must embody worst-case environments can expected from magnetic storms...