10 research outputs found
Extreme energetic electron fluxes in low Earth orbit: Analysis of POES E > 30, E > 100 and E > 300 keV electrons
Energetic electrons are an important space weather hazard. Electrons with energies less than about 100 keV cause surface charging while higher energy electrons can penetrate materials and cause internal charging. In this study we conduct an extreme value analysis of the maximum 3-hourly flux of E> 30 keV, E> 100 keV and E> 300 keV electrons in low Earth orbit as a function of Lâ, for geomagnetic field lines that map to the outer radiation belt, using data from the National Oceanic and Atmospheric Administration (NOAA) Polar Operational Environmental Satellites (POES) from July 1998 to June 2014. The 1 in 10 year flux of E> 30 keV electrons shows a general increasing trend with distance ranging from 1.8Ă107 cmâ2sâ1srâ1 at Lâ = 3.0 to 6.6Ă107 cmâ2sâ1srâ1 at Lâ = 8.0. The 1 in 10 year flux of E> 100 keV electrons peaks at Lâ= 4.5 - 5.0 at 1.9Ă107 cmâ2sâ1srâ1 decreasing to minima of 7.1Ă106 and 8.7Ă106 cmâ2sâ1srâ1 at Lâ = 3.0 and 8.0 respectively. In contrast to the E> 30 keV electrons, the 1 in 10 year flux of E> 300 keV electrons shows a general decreasing trend with distance, ranging from 2.4Ă106 cmâ2sâ1srâ1 at Lâ = 3.0 to 1.2Ă105 cmâ2sâ1srâ1 at Lâ= 8.0. Our analysis suggests that there is a limit to the E> 30 keV electrons with an upper bound in the range 5.1Ă107- 8.8Ă107 cmâ2sâ1srâ1. However, the results suggest that there is no upper bound for the E> 100 keV and E> 300 keV electrons
Extreme relativistic electron fluxes in the Earth's outer radiation belt: Analysis of INTEGRAL IREM data
Relativistic electrons (E > 500 keV) cause internal charging and are an important space weather hazard. To assess the vulnerability of the satellite fleet to these so-called âkillerâ electrons, it is essential to estimate reasonable worst cases, and, in particular, to estimate the flux levels that may be reached once in 10 and once in 100 years. In this study we perform an extreme value analysis of the relativistic electron fluxes in the Earth's outer radiation belt as a function of energy and Lâ. We use data from the Radiation Environment Monitor (IREM) on board the International Gamma Ray Astrophysical Laboratory (INTEGRAL) spacecraft from 17 October 2002 to 31 December 2016. The 1 in 10 year flux at Lâ=4.5, representative of equatorial medium Earth orbit, decreases with increasing energy ranging from 1.36 Ă 107 cmâ2 sâ1 srâ1 MeVâ1 at E = 0.69 MeV to 5.34 Ă 105 cmâ2 sâ1 srâ1 MeVâ1 at E = 2.05 MeV. The 1 in 100 year flux at Lâ=4.5 is generally a factor of 1.1 to 1.2 larger than the corresponding 1 in 10 year flux. The 1 in 10 year flux at Lâ=6.0, representative of geosynchronous orbit, decreases with increasing energy ranging from 4.35 Ă 106 cmâ2 sâ1 srâ1 MeVâ1 at E = 0.69 MeV to 1.16 Ă 105 cmâ2 sâ1 srâ1 MeVâ1 at E = 2.05 MeV. The 1 in 100 year flux at Lâ=6.0 is generally a factor of 1.1 to 1.4 larger than the corresponding 1 in 10 year flux. The ratio of the 1 in 10 year flux at Lâ=4.5 to that at Lâ=6.0 increases with increasing energy ranging from 3.1 at E = 0.69 MeV to 4.6 at E = 2.05 MeV