Characterization of small-scale structures at the magnetopause from ISEE measurements

High-resolution data (covering up to 8 Hz) from the flux gate magnetometers on the two ISEE spacecraft are used to analyze ultralow-frequency (ULF) fluctuations observed at the magnetopause and in the adjacent layers. Intersatellite correlations are computed to show that the same structure can be identified in the fluctuations observed on both spacecraft when the interspacecraft distance is small. Then the possibility of deducing the velocity of the struture from two-point measurements is discussed; it is shown that it can be estimated only in certain cases.