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Found 7 entries in the Bibliography.
Showing entries from 1 through 7
| 2021 |
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A Comparison of Radial Diffusion Coefficients in 1-D and 3-D Long-Term Radiation Belt Simulations AbstractRadial diffusion is one of the dominant physical mechanisms driving acceleration and loss of radiation belt electrons. A number of parameterizations for radial diffusion coefficients have been developed, each differing in the dataset used. Here, we investigate the performance of different parameterizations by Brautigam and Albert (2000), Brautigam et al. (2005), Ozeke et al. (2014), Ali et al. (2015); Ali et al. (2016); Ali (2016), and Liu et al. (2016) on long-term radiation belt modeling using the Versatile El ... . Y. Drozdov, A; Allison, H.; . Y. Shprits, Y; Elkington, S.R.; Aseev, N.A.; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028707 Radiation belts; radial diffusion; VERB code; Van Allen Probes |
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Abstract Following the end of the Van Allen Probes mission, the Arase satellite offers a unique opportunity to continue in-situ radiation belt and ring current particle measurements into the next solar cycle. In this study we compare spin-averaged flux measurements from the MEPe, HEP-L, HEP-H, and XEP-SSD instruments on Arase with those from the MagEIS and REPT instruments on the Van Allen Probes, calculating Pearson correlation coefficient and the mean ratio of fluxes at L* conjunctions between the spacecraft. Arase and Van ... Szabó-Roberts, Mátyás; Shprits, Yuri; Allison, Hayley; Vasile, Ruggero; Smirnov, Artem; Aseev, Nikita; Drozdov, Alexander; Miyoshi, Yoshizumi; Claudepierre, Seth; Kasahara, Satoshi; Yokota, Shoichiro; Mitani, Takefumi; Takashima, Takeshi; Higashio, Nana; Hori, Tomo; Keika, Kunihiro; Imajo, Shun; Shinohara, Iku; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028929 |
| 2020 |
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The Implications of Temporal Variability in Wave-Particle Interactions in Earth s Radiation Belts Changes in electron flux in Earth s outer radiation belt can be modeled using a diffusion-based framework. Diffusion coefficients D for such models are often constructed from statistical averages of observed inputs. Here, we use stochastic parameterization to investigate the consequences of temporal variability in D. Variability time scales are constrained using Van Allen Probe observations. Results from stochastic parameterization experiments are compared with experiments using D constructed from averaged inputs and an aver ... Watt, C.; Allison, H.; Thompson, R.; Bentley, S.; Meredith, N.; Glauert, S.; Horne, R.; Rae, I.; Published by: Geophysical Research Letters Published on: 12/2020 YEAR: 2020 DOI: https://doi.org/10.1029/2020GL089962 probabilistic methods; stochastic parameterization; Van Allen Probes |
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In this study we investigate two distinct loss mechanisms responsible for the rapid dropouts of radiation belt electrons by assimilating data from Van Allen Probes A and B and Geostationary Operational Environmental Satellites (GOES) 13 and 15 into a 3-D diffusion model. In particular, we examine the respective contribution of electromagnetic ion cyclotron (EMIC) wave scattering and magnetopause shadowing for values of the first adiabatic invariant μ ranging from 300 to 3,000 MeV G−1. We inspect the innovation vector ... Cervantes, S.; . Y. Shprits, Y; Aseev, N.; Allison, H.; Published by: Journal of Geophysical Research: Space Physics Published on: 08/2020 YEAR: 2020 DOI: https://doi.org/10.1029/2020JA028208 data assimilation; EMIC waves; magnetopause shadowing; innovation vector; Kalman Filter; radiation belt losses; Van Allen Probes |
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In this study, we performed a series of long-term and individual storm simulations with and without hiss, chorus, and electromagnetic ion cyclotron (EMIC) waves. We compared simulation results incorporating different wave modes with Van Allen Probes flux observations to illustrate how hiss and chorus waves aid EMIC waves in depleting multi-MeV electrons. We found that EMIC, hiss, and chorus waves are required to reproduce satellite measurements in our simulations. Our results indicate that hiss waves play a dominant role in ... . Y. Drozdov, A; Usanova, M.; Hudson, M.; Allison, H.; . Y. Shprits, Y; Published by: Journal of Geophysical Research: Space Physics Published on: 08/2020 YEAR: 2020 DOI: https://doi.org/10.1029/2020JA028282 EMIC waves; Radiation belts; Whistler waves; VERB code; Fokker-Planck diffusion equation; Van Allen Probes |
| 2019 |
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Variability of Quasilinear Diffusion Coefficients for Plasmaspheric Hiss In the outer radiation belt, the acceleration and loss of high-energy electrons is largely controlled by wave-particle interactions. Quasilinear diffusion coefficients are an efficient way to capture the small-scale physics of wave-particle interactions due to magnetospheric wave modes such as plasmaspheric hiss. The strength of quasilinear diffusion coefficients as a function of energy and pitch angle depends on both wave parameters and plasma parameters such as ambient magnetic field strength, plasma number density, and co ... Watt, C.; Allison, H.; Meredith, N.; Thompson, R.; Bentley, S.; Rae, I.; Glauert, S.; Horne, R.; Published by: Journal of Geophysical Research: Space Physics Published on: 10/2019 YEAR: 2019 DOI: 10.1029/2018JA026401 empirical; Magnetosphere; parameterization; stochastic; Van Allen Probes; wave-particle interactions |
| 2018 |
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Determination of the Equatorial Electron Differential Flux From Observations at Low Earth Orbit Variations in the high-energy relativistic electron flux of the radiation belts depend on transport, acceleration, and loss processes, and importantly on the lower-energy seed population. However, data on the seed population is limited to a few satellite missions. Here we present a new method that utilizes data from the Medium Energy Proton/Electron Detector on board the low-altitude Polar Operational Environmental Satellites to retrieve the seed population at a pitch angle of 90\textdegree. The integral flux values measured ... Allison, Hayley; Horne, Richard; Glauert, Sarah; Del Zanna, Giulio; Published by: Journal of Geophysical Research: Space Physics Published on: 11/2018 YEAR: 2018 DOI: 10.1029/2018JA025786 electrons; integral flux; Radiation belts; seed population; Van Allen Probes |
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