Comparison of POES and SAMPEX Observations of Radiation Belt Particles Precipitation

English Abstract:

The phenomenon of Duskside Releativistic Electron Precipitation (DREP) was first proposed by Thorne and Kennel [1971] as scattering of electrons by electromagnetic ion cyclotron (EMIC) waves at the plasmapause boundary on the duskside. Duskside precipitation is known to occur over a broad radial distribution (L = 3–8) and a wide range of magnetic activity levels, from small substorms (Lorentzen et al. 2000) to major Coronal Mass Ejections (CME) driven storms (Kokorowski et al. 2008). Furthermore, it does not strongly correlate with geomagnetic storms, and has slower temporal variations, from minutes to hours (Millan et al., 2002). Comess et al, JGR 2013 analyzed the energy spectrum for such precipitation events from 1992 to 2004 obtained from SAMPEX, a low Earth orbiting satellite, and found they follow an exponentially decreasing distribution. This study re-examines a selection of SAMPEX events with the NOAA-POES satellites, a low altitude, polar orbiting network of spacecraft measuring electrons and protons, which show good conjunctions with SAMPEX on 8th January 2004. Using the SAMPEX e-folding energy and POES Medium Energy Proton and Electron Detector (MEPED 0o) geometric factors obtained through GEANT simulations (Yando et. al., 2011), a model of the expected counts in each POES MEPED channel has been constructed for the events and compared with the observed counts. This work paves the way towards estimating the energy spectrum of precipitation from POES observations, which will allow for detailed observations of precipitation during the post- SAMPEX era.