Influence Of Geomagnetic Field Structure On >= 2 Mev Electron Distribution At The Geostationary Orbit

Based on AE8 electron radiation belt model and various geomagnetic field models, we analyzed the effects of geomagnetic field models, solar wind, geomagnetic disturbance and the pointing of geomagnetic axis on >= 2 MeV electron distribution at the geostationary orbit, examined the differences of >= 2 MeV electron distribution at different longitudes of the geostationary orbit, and made a comparison between the results from models and the observations from GOES satellites. It is shown that the results of >= 2 MeV electron fluxes at the geostationary orbit from AE8+IGRF+T96 model are better than those from AE8+IGRF+OPQ77 model or AE8 +IGRF +T89 model, most of qualitative results from AE8 + IGRF + T96 model are consistent with observations from GOES satellites, and >= 2 MeV electron fluxes at the geostationary orbit from AE8+IGRF+T96 model have a good negative correlation with magnetic shell parameter Lm and a good positive correlation with local magnetic field B. Based on the AE8+IGRF+T96 model, >= 2 MeV electron fluxes at the geostationary orbit each minute during 2010 are calculated by the assumption of constant solar wind conditions and geomagnetic disturbances. The data reveal that the ratios of the maximal to minimal values of >= 2 MeV electron fluxes at the geostationary orbit each minute vary from 2. 50 to 7. 51 in one year, with a main period of 1 day and the variation of ratios each day more than 3, the ratios of the maximal to minimal values of >= 2 MeV electron fluxes for any geostationary satellite each day are within the range from 2. 98 to 6. 00 in one year, varying with the time and the location, and the maximum and minimum values of >= 2 MeV electron daily fluences for the geostationary satellites at the same day in one year appear near 170 degrees W and 70 degrees W, respectively, with their the ratios varying from 1. 86-2. 13. The variations of >= 2 MeV electron distribution at the geostationary orbit above are mainly due to Lm, and the effect of B/B-o is less than 5%, where B-o is the minimal value of magnetic field at any field line. Therefore, the influence of geomagnetic field structure, especially the Lm parameter, should be considered for developing the model of >= 2 MeV high energy electron flux distribution at the geostationary orbit.