A5070208570- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Earthquake Detection and Analysis
- Astro and Planetary Science
- Atmospheric Ozone and Climate
- Oceanographic and Atmospheric Processes
- Geophysics and Gravity Measurements
- Solar Radiation and Photovoltaics
- Meteorological Phenomena and Simulations
- Gas Dynamics and Kinetic Theory
- Biotechnology and Related Fields
- Methane Hydrates and Related Phenomena
- Astrophysics and Cosmic Phenomena
- Spacecraft and Cryogenic Technologies
- Health Systems, Economic Evaluations, Quality of Life
- Laser-Plasma Interactions and Diagnostics
- Radiation Therapy and Dosimetry
- Modular Robots and Swarm Intelligence
- Scientific Computing and Data Management
- GNSS positioning and interference
- Seismic Waves and Analysis
- Distributed and Parallel Computing Systems
- Electrohydrodynamics and Fluid Dynamics
- Fire effects on concrete materials
Johns Hopkins University Applied Physics Laboratory
2020-2025
Johns Hopkins University
2021-2024
Boston University
2015-2022
Allentown Public Library
2021
Murray State University
2010
Abstract Thermospheric mass density perturbations are commonly observed during geomagnetic storms and fundamental to upper atmosphere dynamics, but the sources of these not well understood. Large neutral greatly affect drag experienced by low Earth orbit. We investigated thermospheric at all latitudes along CHAMP GRACE satellite trajectories August 24–25, 2005 storm. Observations show that large enhancements occurred only high latitudes, also globally. were seen in equatorial regions away...
Abstract The role of diffuse electron precipitation in the formation subauroral polarization streams (SAPS) is investigated with Multiscale Atmosphere‐Geospace Environment (MAGE) model. Diffuse derived from distribution drifting electrons. SAPS manifest themselves as a separate mesoscale flow channel duskside ionosphere, which gradually merges primary auroral convection toward dayside equatorward boundary approaches poleward Region‐2 field‐aligned currents (FACs) boundary. expand to lower...
Abstract Solar eruptions cause geomagnetic storms in the near‐Earth environment, creating spectacular aurorae visible to human eye and invisible dynamic changes permeating all of geospace. Just equatorward aurora, radars satellites often observe intense westward plasma flows called subauroral polarization streams (SAPS) dusk‐to‐midnight ionosphere. SAPS occur across a narrow latitudinal range lead frictional heating ionospheric atmospheric neutral gas. also generate small‐scale waves density...
Abstract A characteristic feature of the main phase geomagnetic storms is dawn‐dusk asymmetric depression low‐ and mid‐latitude ground magnetic fields, with largest in dusk sector. Recent work has shown, using data taken from hundreds storms, that this asymmetry strongly correlated enhancements dawnside westward electrojet been interpreted as a “dawnside current wedge” (DCW). Its ubiquity suggests it an important aspect stormtime magnetosphere‐ionosphere (MI) coupling. In we simulate...
Abstract On 21 June 2022, during the annual Geospace Environment Modeling (GEM) workshop, a panel discussion titled “Radiation Belt Loss: The Long‐Standing Debate Part II” was organized by focus group “System Understanding of Radiation Particle Dynamics.” focused on unresolved questions regarding mechanisms driving electron loss in Earth's radiation belts, discussing topics including magnetopause shadowing, outward radial transport, and wave‐particle interactions particle precipitation. In...
Abstract Shock-generated transients, such as hot flow anomalies (HFAs), upstream of planetary bow shocks, play a critical role in electron acceleration. Using multimission data from NASA’s Magnetospheric Multiscale and ESA’s Cluster missions, we demonstrate the transmission HFAs through Earth’s quasi-parallel shock, accelerating electrons to relativistic energies process. Energetic initially accelerated are shown remain broadly confined within transmitted transient structures downstream,...
Global numerical simulations are a valuable tool for understanding the Sun-Earth interaction as they provide more complete picture of system when compared to typically sparse observations. Yet, comparison global against observations is complicated by inherent uncertainty that observed phenomena occurred at same time and location in simulation domain. It therefore common use aggregate measures interaction, such Dst AL indices cross-polar cap potential, with downside missing details,...
We study the Kelvin–Helmholtz instability (KHI) for general case of a compressible, nonhomogeneous, magnetized plasma flow. The is limited to vortex sheet interface with an imposed parallel magnetic field. introduce new formalism based on convective Mach number Mc, Alfvénic MAc, and total that combines two. derive analytic expression KHI growth rate homogeneous flow (i.e., zero Atwood number, A=0) converges toward both unmagnetized compressible Chandrasekhar's incompressible Otherwise,...
The Kelvin-Helmholtz instability at the magnetospheric boundary plays a crucial role in solar wind-magnetosphere-ionosphere coupling, particle entry, and energization. full extent of its impact has remained an open question due, part, to global models without sufficient resolution capture waves higher latitudes. Using magnetohydrodynamic simulations, we investigate event when Magnetospheric Multiscale (MMS) mission observed periodic low-frequency dawn-flank, high-latitude layer. We show...
Abstract Typical planetary and satellite exospheres are in nonequilibrium conditions, which means that a distribution function describes these environments is far from Maxwellian. It even more true when considering transportation of energetic ions magnetospheres, making it necessary to solve the Boltzmann equation order capture kinetic effects modeling evolution describing such environments. Among various numerical methods, Monte Carlo approach one most used for solving equations. That...
Abstract Simultaneous observations from Van Allen Probes in Earth's outer radiation belt (∼4–6 R E ) and Magnetospheric Multiscale (MMS) the magnetotail plasma sheet at >20 geocentric distance are used to compare relative levels of relativistic electron phase space density (PSD) for constant values first adiabatic invariant, M. We present new evidence two events showing: (a) times, there is sufficient PSD central provide a source >1 MeV electrons into belt; (b) most intense not...
Abstract Voyager 1 and 2 data from the vicinity of heliopause very local interstellar medium are reexamined to better understand confounding lack rotation in magnetic field ( B -field) across observed by both Voyagers, despite their large spatial separations (>100 au). Using three estimates for orientation -field pristine four models heliosphere, we calculate draped orientations along model heliopauses compare those observations. At expected -fields inconsistent with after boundary...
Abstract Interstellar neutral (ISN) hydrogen is the most abundant species in outer heliosheath and very local interstellar medium (VLISM). Charge-exchange collisions result filtration, reducing ISN density inside heliosphere. Additionally, these atoms are intensively ionized close to Sun, resulting a substantial reduction of their within few astronomical units from Sun. The products this ionization—pickup ions (PUIs)—are detected by charged particle detectors. Solar Wind Around Pluto...
Abstract Understanding the physical mechanisms responsible for cross‐scale energy transport and plasma heating from solar wind into Earth's magnetosphere is of fundamental importance magnetospheric physics understanding these processes in other places universe with comparable parameter ranges. This paper presents observations Magnetosphere Multiscale (MMS) mission at dawn‐side high‐latitude dayside boundary layer on February 25, 2016 between 18:55 20:05 UT. During this interval, MMS...
Abstract Global models of the heliosphere are critical tools used in interpretation heliospheric observations. There several three-dimensional magnetohydrodynamic (MHD) that rely on different strategies and assumptions. Until now only one paper has compared global models, but without magnetic field effects. We compare results two MHD BU Moscow models. Both use identical boundary conditions to how numerical approaches physical assumptions contribute solution. Based treatments discontinuities,...
Abstract The formation of the stormtime ring current is a result inward transport and energization plasma sheet ions. Previous studies have demonstrated that significant fraction total takes place in form bursty bulk flows, known theoretically as flux tube entropy‐depleted “bubbles.” However, it remains an open question to what extent bubbles contribute buildup current. Using Multiscale Atmosphere Geospace Environment Model, we present case study 17 March 2013 storm, including quantitative...
Abstract Neutral hydrogen has been shown to greatly impact the plasma flow in heliosphere and location of heliospheric boundaries. We present results Solar Wind with Hydrogen Ion Exchange Large-scale Dynamics (SHIELD) model, a new, self-consistent, kinetic–MHD model outer within Space Weather Modeling Framework. The charge exchange mean free path is on order size heliosphere; therefore, neutral atoms cannot be described as fluid. numerical code SHIELD couples MHD solution for single fluid...
Abstract Ly α absorption profiles have been used to detect astrospheres and heliospheric from the hydrogen wall heliotail. Using magnetohydrodynamic models of heliosphere, we can compare simulated observed probe neutral within near heliosphere. There is an ongoing controversy whether heliosphere has a long “comet-like” tail or short “croissant-like” tail. Here present first investigation using croissant-like With identical boundary conditions BU model, which presents tail, Moscow comet-like...
Abstract During geomagnetic storms relativistic outer radiation belt electron flux exhibits large variations on rapid time scales of minutes to days. Many competing acceleration and loss processes contribute the dynamic variability belts; however, distinguishing relative contribution each mechanism remains a major challenge as they often occur simultaneously over wide range spatiotemporal scales. In this study, we develop new comprehensive model for storm‐time dynamics by incorporating...
Traditionally, the solar magnetic field has been considered to have a negligible effect in outer regions of heliosphere. Recent works shown that may play crucial role collimating plasma heliosheath. Interstellar Boundary Explorer (IBEX) observations heliotail indicated latitudinal structure varying with energy energetic neutral atom (ENA) fluxes. At energies ~1 keV, ENA fluxes show an enhancement at low latitudes and deficit ENAs near poles. >2.7 had within latitudes, lobes higher flux This...
Abstract The geospace plume, referring to the combined processes of plasmaspheric and ionospheric storm‐enhanced density (SED)/total electron content (TEC) plumes, is one unique features geomagnetic storms. apparent spatial overlap joint temporal evolution between plume equatorial mapping SED/TEC indicate strong magnetospheric‐ionospheric coupling. However, a systematic modeling study factors contributing development has not yet been performed due lack sufficiently comprehensive model...
Abstract The shape of the heliosphere is thought to resemble a long, comet tail, however, recently it has been suggested that tailless with two-lobe structure. latter study was done three-dimensional (3D) magnetohydrodynamic code, which treats ionized and neutral hydrogen atoms as fluids. Previous studies described neutrals kinetically claim this removes structure heliosphere. In work, we use newly developed Solar-wind Hydrogen Ion Exchange Large-scale Dynamics (SHIELD) model. SHIELD...
In the heliosheath (HS), Voyager 2 has observed a flow with constant radial velocity and magnetic flux conservation. 1, however, decrease in flow's an order of magnitude flux. We investigate role 11 yr solar cycle variation field strength on within HS using global 3D magnetohydrodynamic model heliosphere. use time latitude-dependent wind density inferred from Solar Heliospheric Observatory/SWAN interplanetary scintillations data implemented variations derived 27 day averages average at 1 AU...
The formation of the stormtime ring current is a result inward transport and energization plasma sheet ions. Previous studies have demonstrated that significant fraction total takes place in form bursty bulk flows (BBFs), known theoretically as flux tube entropy-depleted “bubbles.’ However, it remains an open question to what extent bubbles contribute buildup current. Using Multiscale Atmosphere Geospace Environment (MAGE) Model, we present case study March 17, 2013 storm, including...