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Electron Precipitation From the Outer Radiation Belt During the St. Patrick's Day Storm 2015: Observations, Modeling, and Validation
Author(s) -
Clilverd Mark A.,
Rodger Craig J.,
Kamp Max,
Verronen Pekka T.
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2019ja027725
Subject(s) - van allen radiation belt , geomagnetic storm , electron precipitation , atmospheric sciences , flux (metallurgy) , storm , precipitation , earth's magnetic field , van allen probes , ionosphere , tec , noon , physics , environmental science , climatology , geophysics , geology , meteorology , magnetosphere , magnetic field , materials science , quantum mechanics , metallurgy
Recently, a model for medium‐energy (30–1000 keV) radiation belt‐driven electron precipitation (ApEEP) has been put forward for use in decadal to century‐long climate model runs as part of the Climate Modelling Intercomparison Project, phase 6 (CMIP6). The ApEEP model is based on directly observed precipitation data spanning 2002–2012 from the constellation of low‐Earth‐orbiting Polar Operational Environmental Satellites (POES). Here, we test the ApEEP model's ability using its magnetic local time variant, ApEEP_MLT, to accurately represent electron precipitation fluxes from the radiation belts during a large geomagnetic storm that occurred outside of the span of the development data set. In a study of narrowband subionospheric very low frequency (VLF) transmitter data collected during March 2015, continuous phase observations have been analyzed throughout the entire St. Patrick's Day geomagnetic storm period for the first time. Using phase data from the U.K. transmitter, call‐sign GVT (22.1 kHz), received in Reykjavik, Iceland, electron precipitation fluxes from L = 2.8 to 5.4 are calculated around magnetic local noon (12 MLT) and magnetic midnight (00 MLT). VLF‐inferred >30‐keV fluxes are similar to the equivalent directly observed POES fluxes. The ApEEP_MLT >30‐keV fluxes for L < 5.5 describe the overall St. Patrick's Day geomagnetic storm‐driven flux enhancement well, although they are a factor of 1.7 (1.3) lower than POES (VLF‐inferred) fluxes during the recovery phase. Such close agreement in >30‐keV flux levels during a large geomagnetic storm, using three different techniques, indicates this flux forcing are appropriate for decadal climate simulations for which the ApEEP model was created.