Title:

 

Statistical study of the spatial scale of Relativistic Electron Precipitation with NOAA POES.

 

 

Abstract:

 

Relativistic Electron Precipitation (REP) in the atmosphere can contribute significantly to electron loss from the outer radiation belts both during quiet times and conditions of geomagnetic activity. In order to estimate the contribution to this loss, it is important to estimate the spatial extent of the precipitation region. We observed REP with the 0 deg Medium Energy Proton Electron Detector (MEPED) on board Polar Orbiting Environmental Satellites (POES), for 15 years (2000-2014) and used both single and multi satellite measurements to estimate an average extent of region of precipitation in L shell and Magnetic Local Time (MLT). In the duration of 15 years (2000-2014), 31035 REP's were found in this study. Events were found to split into two classes; one class of events coincided with proton precipitation in the P1 channel (30-80 keV), were located in the dusk and early morning sector, and were more localized in L shell and magnetic local time (dMLT ~0-2 hrs, dL~0.25-0.5), on the other hand, the other class of events did not include proton precipitation, and were located mostly in the midnight sector and were wider in L shell (dL ~1-2.5) but localized in MLT (dMLT ~0-2 hrs); both classes occurring mostly during the declining phase of the solar cycle and Geo magnetically active times. The events located in the midnight sector for both classes were found to be associated with tail magnetic field stretching which could be due to the fact that they tend to occur mostly during Geo magnetically active times, or could imply that precipitation is caused by current sheet scattering.