On the accuracy of a priori predictions of the magnetopause position (According to the INTERBALL Project Data)

The accuracy of a priori model predictions of a magnetopause position is es timated in the paper. These predictions are used in planning communication sessions and in control of scientific instrumentation of the Interball-1 sa tellite. With this purpose the real time moments of magnetosphere boundary crossings are compared with magnetopause position calculations from the emp irical model. As a result of the analysis of 82 single magnetopause crossin gs by the Interball-1 satellite, the error in predicting the spatial locati on of the boundary is shown to vary in the range from -2R(E) to +5R(E) (R-E is the Earth's radius). More frequently (in 65% of cases) the real magneto pause turns out to be closer to the Earth than is predicted by the model; i n half of the cases the magnetopause prediction error does not exceed 1R(E) . The discrepancy of the measured moments of boundary crossings and those p redicted by the preliminary model calculations disregarding the external co nditions reaches 1-2 h in the majority of cases (55 and 80% of events, resp ectively). In these cases, the real magnetopause is recorded before the pre dicted moment more frequently (in 67% of events).