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A statistical approach to determining energetic outer radiation-belt electron precipitation fluxes

Wedlund, Mea Simon; Clilverd, Mark A.; Rodger, Craig J.; Cresswell-Moorcock, Kathy; Cobbett, Neil; Breen, Paul; Danskin, Donald; Spanswick, Emma; Rodriguez, Juan V.. 2014 A statistical approach to determining energetic outer radiation-belt electron precipitation fluxes. Journal of Geophysical Research: Space Physics, 119 (5). 3961-3978. 10.1002/2013JA019715

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Abstract/Summary

Sub-ionospheric radio-wave data from an AARDDVARK receiver located in Churchill, Canada, is analysed to determine the characteristics of electron precipitation into the atmosphere over the range 3 < L < 7. The study advances previous work by combining signals from two US transmitters from 20 July – 20 August 2010, allowing error estimates of derived electron precipitation fluxes to be calculated, including the application of time-varying electron energy spectral gradients. Electron precipitation observations from the NOAA POES satellites, and a ground-based riometer provide inter-comparison, and context, for the AARDDVARK measurements. AARDDVARK radiowave propagation data showed responses suggesting energetic electron precipitation from the outer radiation belt starting 27 July 2010, and lasting ~20 days. The uncertainly in >30 keV precipitation flux determined by the AARDDVARK technique was found to be ±10%. Peak >30 keV precipitation fluxes of AARDDVARK-derived precipitation flux during the main- and recovery-phase of the largest geomagnetic storm, that started on 04 August 2010, were >105 el. cm-2 s-1 sr-1. The largest fluxes observed by AARDDVARK occurred on the dayside, and were delayed by several days from the start of the geomagnetic disturbance. During the main phase of the disturbances nightside fluxes were dominant. Significant differences in flux estimates between POES, AARDDVARK and the riometer were found after the main phase of the largest disturbance, with evidence provided to suggest that >700 keV electron precipitation was occurring. Currently the presence of such relativistic electron precipitation introduces some uncertainty in the analysis of AARDDVARK data, given the assumption of a power-law electron precipitation spectrum.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1002/2013JA019715
Programmes: BAS Programmes > Polar Science for Planet Earth (2009 - ) > Climate
BAS Programmes > BAS Corporate
ISSN: 21699380
Additional Keywords: electron precipitation, geomagnetic storm
Date made live: 13 May 2014 08:45 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/507231

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