Correlation of energetic electron fluxes at geostationary orbit with solar wind parameters and geomagnetic activity indices during solar cycles 22 and 23

We studied correlation of energetic electron fluxes at geostationary orbit (GO) with solar wind parameters (V and n) and geomagnetic activity indices (PC, AE, K p, and D st) during solar cycles 22 and 23. We used data on electron fluxes recorded by LANL satellites (electron energy range from 24.1 keV to 2.0 MeV) in 1996-2009 and GOES satellites (Е>2 MeV) in 1986-2009. The correlation was found to change in the following way during a solar cycle: the correlation of electron fluxes having different energies with solar wind parameters and geomagnetic activity indices was highest at solar minimum; it was lowest at solar maximum and at the initial decay phase of a solar cycle. According to the analysis of 3-month periods during solar cycle 23, the solar wind velocity is the best indicator of relativistic electron fluxes in about 60 % of cases. In about 20 % of cases, the best indicator is the solar wind density; in other 20 % of cases, these are the geomagnetic activity indices. For low-energy electron fluxes (up to 100-150 keV), the highest correlation with geomagnetic activity indices is observed in virtually all cases. The results are discussed from the viewpoint of conditions in the solar wind and in the magnetosphere.