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Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Van Allen Probe Observations

We use measurements from NASA's Van Allen Probes to calculate the decay time constants for electrons over a wide range of energies (30 keV to 4 MeV) and [Formula: see text] values ( [Formula: see text] = 1.3–6.0) in the Earth's radiation belts. Using an automated routine to identify flux d...

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Autores principales: Claudepierre, S. G., Ma, Q., Bortnik, J., O'Brien, T. P., Fennell, J. F., Blake, J. B.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7375131/
https://www.ncbi.nlm.nih.gov/pubmed/32713975
http://dx.doi.org/10.1029/2019GL086053
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author Claudepierre, S. G.
Ma, Q.
Bortnik, J.
O'Brien, T. P.
Fennell, J. F.
Blake, J. B.
author_facet Claudepierre, S. G.
Ma, Q.
Bortnik, J.
O'Brien, T. P.
Fennell, J. F.
Blake, J. B.
author_sort Claudepierre, S. G.
collection PubMed
description We use measurements from NASA's Van Allen Probes to calculate the decay time constants for electrons over a wide range of energies (30 keV to 4 MeV) and [Formula: see text] values ( [Formula: see text] = 1.3–6.0) in the Earth's radiation belts. Using an automated routine to identify flux decay events, we construct a large database of lifetimes for near‐equatorially mirroring electrons over a 5‐year interval. We provide the first accurate estimates of the long decay timescales in the inner zone ( [Formula: see text] 100 days), which are highly resolved in energy and free from proton contamination. In the slot region and outer zone, we compare our lifetime calculations with prior empirical estimates and find good quantitative agreement (lifetimes [Formula: see text] 1–20 days). The comparisons suggest that some prior estimates may overestimate electron lifetimes between [Formula: see text] 2.5–4.5 due to instrumental effects and/or background contamination. Previously reported two‐stage decays are explicitly demonstrated to be a consequence of using integral fluxes.
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spelling pubmed-73751312020-07-23 Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Van Allen Probe Observations Claudepierre, S. G. Ma, Q. Bortnik, J. O'Brien, T. P. Fennell, J. F. Blake, J. B. Geophys Res Lett Research Letters We use measurements from NASA's Van Allen Probes to calculate the decay time constants for electrons over a wide range of energies (30 keV to 4 MeV) and [Formula: see text] values ( [Formula: see text] = 1.3–6.0) in the Earth's radiation belts. Using an automated routine to identify flux decay events, we construct a large database of lifetimes for near‐equatorially mirroring electrons over a 5‐year interval. We provide the first accurate estimates of the long decay timescales in the inner zone ( [Formula: see text] 100 days), which are highly resolved in energy and free from proton contamination. In the slot region and outer zone, we compare our lifetime calculations with prior empirical estimates and find good quantitative agreement (lifetimes [Formula: see text] 1–20 days). The comparisons suggest that some prior estimates may overestimate electron lifetimes between [Formula: see text] 2.5–4.5 due to instrumental effects and/or background contamination. Previously reported two‐stage decays are explicitly demonstrated to be a consequence of using integral fluxes. John Wiley and Sons Inc. 2020-02-07 2020-02-16 /pmc/articles/PMC7375131/ /pubmed/32713975 http://dx.doi.org/10.1029/2019GL086053 Text en ©2020. The Authors. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Letters
Claudepierre, S. G.
Ma, Q.
Bortnik, J.
O'Brien, T. P.
Fennell, J. F.
Blake, J. B.
Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Van Allen Probe Observations
title Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Van Allen Probe Observations
title_full Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Van Allen Probe Observations
title_fullStr Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Van Allen Probe Observations
title_full_unstemmed Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Van Allen Probe Observations
title_short Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Van Allen Probe Observations
title_sort empirically estimated electron lifetimes in the earth's radiation belts: van allen probe observations
topic Research Letters
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7375131/
https://www.ncbi.nlm.nih.gov/pubmed/32713975
http://dx.doi.org/10.1029/2019GL086053
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