13 June, 2016

Energetic electrons are an important space weather hazard. In this paper we apply extreme value analysis to 16 years of operational satellite data from the NOAA Polar Operational Environmental Satellites (POES) to determine the 1 in 10 and 1 in 100 year flux of E > 30, E > 100 and E > 300 keV electrons as a function of L*. Here L* is a magnetic coordinate, related to the distance from the centre of the Earth to the equatorial crossing of the dipole field line passing through the satellite in units of Earth radii.

The 1 in 10 year flux of E > 30 keV electrons show a general increasing trend with L* ranging from 1.8 x 107 cm-2s-1sr-1 at L* = 3.0 to 6.6 x 107 cm-2s-1sr-1 at L* = 8.0. In contrast the 1 in 10 year flux of E > 300 keV electrons decreases with L* ranging from 2.4 x 106 cm-2s-1sr-1 at L* = 3.0 to 1.2 x 105 cm-2s-1sr-1 at L* = 8.0. The 1 in 100 year fluxes of E > 30 and E > 300 keV electrons are generally factors of 1.1-1.5 and 1.7-5.9 times larger than the corresponding 1 in 10 year events respectively.

The 1 in N year flux levels as a function of energy and L* computed in this study serve as benchmarks against which to compare other space weather events. The results may also be used to compute the return period of any given space weather event as a function of energy and L* to determine if the event was particularly extreme at any given energy or location.

 

The Paper
Extreme energetic electron fluxes in low Earth orbit: Analysis of POES E > 30, E > 100, and E > 300 keV electrons

Authors
Nigel P. Meredith, Richard B. Horne, John D. Isles, and Janet C. Green

Published by
Space Weather, 14, 136–150, doi: 10.1002/2015SW001348