A5079308156- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Earthquake Detection and Analysis
- Atmospheric Ozone and Climate
- Astro and Planetary Science
- Meteorological Phenomena and Simulations
- Geophysics and Gravity Measurements
- Spacecraft Design and Technology
- Tropical and Extratropical Cyclones Research
- Space exploration and regulation
- GNSS positioning and interference
- Atmospheric and Environmental Gas Dynamics
- Computational Physics and Python Applications
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Scientific Computing and Data Management
- Radiation Effects in Electronics
- Space Exploration and Technology
- Solar Radiation and Photovoltaics
- Space Satellite Systems and Control
- Planetary Science and Exploration
- Radiation Therapy and Dosimetry
- Graphite, nuclear technology, radiation studies
- Pulsed Power Technology Applications
Los Alamos National Laboratory
2016-2025
University of America
2024
Catholic University of America
2024
University of New Hampshire
2024
University of Alberta
2022
University of Newcastle Australia
2005-2010
Centre Hospitalier de Luxembourg
2008
British Antarctic Survey
2004-2007
Natural Environment Research Council
2004-2007
University of Southampton
2001-2006
The Van Allen radiation belts contain ultrarelativistic electrons trapped in Earth's magnetic field. Since their discovery 1958, a fundamental unanswered question has been how can be accelerated to such high energies. Two classes of processes have proposed: transport and acceleration from source population located outside the (radial acceleration) or lower-energy relativistic energies situ heart (local acceleration). We report measurements NASA's Radiation Belt Storm Probes that clearly...
Abstract Quantitative assessment of modeling and forecasting continuous quantities uses a variety approaches. We review existing literature describing metrics for forecast accuracy bias, concentrating on those based relative errors percentage errors. Of these metrics, the mean absolute error (MAPE) is one most common across many fields has been widely applied in recent space science we highlight benefits drawbacks MAPE proposed alternatives. then introduce log ratio derive from it two...
[1] Thirty years ago Paulikas and Blake (1979) showed a remarkable correlation between geosynchronous relativistic electron fluxes solar wind speed (Vsw). This seminal result has been foundation of radiation belt studies, space weather forecasting, current understanding coupling. We have repeated their analysis with considerably longer-running data set (1989–2010) from the Los Alamos National Laboratory energetic particle instruments several surprising results. Rather than roughly linear Vsw...
Abstract The DREAM3D diffusion model is applied to Van Allen Probes observations of the fast dropout and strong enhancement MeV electrons during October 2012 “double‐dip” storm. We show that in order explain very different behavior two “dips,” all three dimensions (energy, pitch angle, L * ) coupled with data‐driven, event‐specific inputs, boundary conditions required. Specifically, we find outward radial solar wind‐driven magnetopause, an chorus wave model, a dynamic lower‐energy seed...
Electromagnetic ion cyclotron (EMIC) waves have been observed during geomagnetic storms and are thought to contribute ring current radiation belt particle loss the main phase. Ground‐based storm time studies alternatively observe majority of Pc1‐2 pulsations recovery In this study we look at occurrences EMIC 119 occurring throughout CRRES mission. The were defined using Sym‐H index. was divided into three phases: pre‐onset, main, (80% minimum value). majority, 56.25%, found occur phase,...
Abstract On 30 September 2012, a flux “dropout” occurred throughout Earth's outer electron radiation belt during the main phase of strong geomagnetic storm. Using eight spacecraft from NASA's Time History Events and Macroscale Interactions Substorms (THEMIS) Van Allen Probes missions NOAA's Geostationary Operational Environmental Satellites constellation, we examined full extent timescales dropout based on particle energy, equatorial pitch angle, radial distance, species. We calculated space...
Abstract Drastic variations of Earth's outer radiation belt electrons ultimately result from various competing source, loss, and transport processes, to which wave‐particle interactions are critically important. Using 15 spacecraft including NASA's Van Allen Probes, THEMIS, SAMPEX missions NOAA's GOES POES constellations, we investigated the evolution during strong geomagnetic storm 30 September 3 October 2012. This storm's main phase dropout exhibited enhanced losses atmosphere at L* <...
Abstract To achieve a better understanding of the dominant loss mechanisms for rapid dropouts radiation belt electrons, three distinct dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations pitch angle distribution electron fluxes and electromagnetic ion cyclotron (EMIC) waves analyzed to determine effects atmospheric precipitation due scattering induced EMIC waves. Last closed drift shells (LCDS) magnetopause standoff position obtained...
Electromagnetic ion cyclotron (EMIC) waves may contribute to ring current and radiation belt electron losses, theoretical studies suggest these processes be most effective during the main phase of geomagnetic storms. However, ground‐based signatures EMIC waves, Pc1–Pc2 pulsations, are observed more frequently recovery phase. We investigate association with various storm phases in case statistical 22 storms over 1996–2003, an associated Dst < −30 nT. High‐resolution data from GOES 8, 9, 10...
We present a statistical study of relativistic electron counts in the radiation belt across range drift shells (L*>4) combining data from nine combined X-ray dosimeters (CXD) on global positioning system (GPS) constellation. The response as functions time, energy and shell are examined statistically for 67 solar wind stream interfaces (SIs); two-dimensional superposed epoch analysis is performed with CXD data. For these epochs we dropouts concurrent variations key geophysical parameters....
The Dynamic Radiation Environment Assimilation Model (DREAM) was developed to provide accurate, global specification of the Earth's radiation belts and better understand physical processes that control belt structure dynamics. DREAM is designed using a modular software approach in order computational framework makes it easy change components such as magnetic field model, dynamics boundary conditions, etc. This paper provides broad overview model summary some principal results date. We...
The images taken by the Heliospheric Imagers (HIs), part of SECCHI imaging package onboard pair STEREO spacecraft, provide information on radial and latitudinal evolution plasma compressed inside corotating interaction regions (CIRs). A density wave imaged HI instrument STEREO-B was found to propagate towards STEREO-A, enabling a comparison between simultaneous remote-sensing in situ observations its structure be performed. In measurements made STEREO-A show that is associated with passage...
Abstract Geomagnetic indices are convenient quantities that distill the complicated physics of some region or aspect near‐Earth space into a single parameter. Most best‐known calculated from ground‐based magnetometer data sets, such as Dst, SYM‐H, Kp, AE, AL, and PC. Many models have been created predict values these indices, often using solar wind measurements upstream Earth input variables to calculation. This document reviews current state geomagnetic methods used assess their ability...
Abstract Since 2000, Los Alamos National Laboratory (LANL) Combined X‐ray and Dosimeter (CXD) Burst Detector for Block II‐R (BDD‐IIR) instruments have been fielded on Global Positioning System (GPS) satellites. Today, 21 of the 31 operational GPS satellites are equipped with a CXD detector further 2 carry BDD‐IIR. Each these measures wide range energetic electrons protons. These data now publicly released under terms Executive Order Coordinating Efforts to Prepare Nation Space Weather...
Abstract We present simulations of the outer radiation belt electron flux during March 2015 and 2013 storms using a radial diffusion model. Despite differences in disturbance short‐time intensity between two storms, response ultra‐relativistic electrons was remarkably similar, both showing sudden drop followed by rapid enhancement to levels over an order magnitude higher than those observed pre‐storm interval. Simulations storm show that outward can explain dropout down L *~4. However,...
Abstract The radiation belts of the Earth, filled with energetic electrons, comprise complex and dynamic systems that pose a significant threat to satellite operation. While various models electron flux both for low relativistic energies have been developed, behavior medium energy (120–600 keV) especially in MEO region, remains poorly quantified. At these energies, electrons are driven by convective diffusive transport, their prediction usually requires sophisticated 4D modeling codes. In...
AP1903 is a novel gene‐targeted drug that being developed for use in drug‐regulated cell therapies. An intravenous, single‐blind, placebo‐ and saline‐controlled, ascending‐dose study was performed to evaluate the safety, tolerability pharmacokinetics of AP1903. Twenty‐eight normal healthy male volunteers were randomized into five dosage groups (0.01, 0.05, 0.1, 0.5, 1 mg/kg). Within each group, 4 received single dose AP1903, volunteer an equal volume placebo, saline. The only exception 0.5...
A rapid loss of energetic (>230 keV) electrons from the outer radiation belt was observed with GPS constellation between 1430 and 1730 UTC on 7 May 2007. The occurred 4 < L * 6 over all measured energies above 230 keV. Currently accepted mechanisms include magnetopause shadowing and/or outward diffusion, precipitation to atmosphere due wave‐particle interactions. Here timescale is ∼2 hr, near = 8, which requires unrealistically high diffusion rates. Current estimates timescales...
We re‐examine whether substorms are triggered by solar wind fluctuations or an internal magnetospheric instability comparing the statistical associations between substorm onsets and (1) external trigger definition, (2) a simple definition of only prior loading energy that is subset definition. Statistical calculated both for observed generated Minimal Substorm Model in which purely internally triggered. Thence we argue minimum interval necessary condition onset, subsequent northward IMF...
Abstract Energetic electron observations in Earth's radiation belts are typically sparse, and multipoint studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of Combined X‐ray Dosimeter (CXD), currently flown 19 satellites Global Positioning System (GPS) constellation, by cross‐calibrating energetic measurements against data from Van Allen Probes. By breaking our cross calibration into two parts—one that removes any spectral assumptions CXD flux...
Abstract We simulated the entire month of January 2005 using Space Weather Modeling Framework (SWMF) with observed solar wind data as input. conducted this simulation and without an inner magnetosphere model tested two different grid resolutions. evaluated model's accuracy in predicting K p , S Y M ‐ H A L cross‐polar cap potential (CPCP). find that does excellent job index, a root‐mean‐square error (RMSE) 17–18 nT. is predicted well during storm time conditions but overpredicted quiet times...
Abstract We provide the first ever characterization of primary modes ionospheric Hall and Pedersen conductance variability as empirical orthogonal functions (EOFs). These are derived from six satellite years Defense Meteorological Satellite Program (DMSP) particle data acquired during rise solar cycles 22 24. The 60 million DMSP spectra were each processed through Global Airlglow Model. Ours is large‐scale analysis conductances completely free assumption incident electron energy spectra....
Abstract Fast dropout of relativistic and ultrarelativistic electrons at both high low L* regions were observed during the intense coronal mass ejection driven storm in June 2015. An improved radial diffusion model, using an event‐specific last closed drift shell newly available coefficients ( D LL ), is implemented to simulate magnetopause shadowing loss electrons. The model captures fast well after interplanetary shocks, reproduces initial adiabatic high‐energy storage ring second strong...