Relativistic Electron Enhancement (REE) Behavior during the Recovery Phase of Solar Cycle 23

Abstract

To quantify the relationship between geomagnetic storms and relativistic electron enhancement (REE) at geosynchronous orbit and magnetic storms, a full solar cycle (1996–2006) of data has been examined.  The relativistic electron fluxes of the earth’s outer belt are subjected to strong temporal variations.  The most prominent changes are initiated by the fast solar wind streams which often also caused enhanced substorm activity and magnetic storms.  We considered the weak, moderate and intense geomagnetic storms using the index for 313 storms that occurred during Solar Cycle 23 (in the interval from January 1996 to December 2006).  The relativistic electron fluence data were based on fluxes observed by the GOES geosynchronous satellites.

In the present study, we analyzed 313 Intense, Moderate and Weak storms observed at three different latitudes. A statistical study has been performed to quantify the REE behavior before and after the recovery phase of magnetic storms.  Every relativistic electron event was associated with a magnetic storm, but, magnetic storms could occur without appreciable enhancement of the relativistic electron fluxes.  More input parameters such as; solar wind velocity, dynamic pressure, and density, were thus used to make a cross-correlation analysis to determine what parameters might influence the flux of relativistic electrons.

Keywords: Geomagnetic storms, Geosynchronous orbit, Dst index, Relativistic Electron Enhancement.