Study on a forecasting method of the relativistic electron flux at geostationary orbit using geomagnetic pulsation data
利用地磁脉动预报地球同步轨道相对论电子通量的方法研究

Relativistic electron fluxes measured at constant energy undergo large dropouts and enhancements during geomagnetic storms. As far as we know, there are two substantial preconditions for the relativistic electron flux enhancement in the outer radiation belt during geomagnetic storm: the first and the most important is that there must be enough low energy electron (on the order of tens to hundreds of keV ), the so-called seed electron; second, kinds of waves which can contribute to the electron acceleration by wave-particle interaction are necessary. Geomagnetic field data observed by Memambetsu (L=1.57) observatory are used to extract Pi1-2 pulsations during geomagnetic storm. The relativistic electron data at geostationary orbit are from GOES satellites observation. We investigate the relationship between Pi1-2 pulsation duration and relativistic electron flux during the recovery phase, and find that the relativistic electron flux increases with the Pi1-2 pulsation duration. The Pc5 pulsation at geostationary orbit has the similar result, the duration and amplitude of Pc5 pulsation can also impact the relativistic electron flux. Due to this statistic analysis result, a model was developed to forecast the relativistic electron flux at geostationary orbit during the recover phase of the geomagnetic storms. The model uses the duration and amplitude of Pi1 pulsation and Pc5 pulsation as input. Parameters in the model are set by optimizing prediction efficiency (PE) for 38 events during 2004.01~2006.12, and the optimized linear correlation coefficient and PE for these events are 0.82 and 0.67, which means this method is viable.