Intensity correlations and substorm electron drift effects in the outer radiation belt measured with the OGO 3 and ATS 1 satellites

Abstract

During late December 1966 and January 1967 the elliptically orbiting satellite OGO 3 entered the magnetosphere within 30° of the subsolar point and within 10° of the geomagnetic equator. This permits the measurement of rb, the distance to the magnetosphere boundary, which is a necessary parameter for the Mead model magnetic field calculations. The electron fluxes measured by an electron spectrometer and an ion chamber of OGO 3 are correlated with electron fluxes on the geostationary satellite ATS 1 at the exact time when both satellites are on the same drift shells as calculated from the Mead model magnetic field with separations in local time up to 180°. During quiet times an absolute comparison of the fluxes from 50–1000 kev gives a linear relationship indicating agreement of the measurements over a three order-of-magnitude range of intensities. During substorm increases, the ATS 1 and OGO 3 measurements have similar profiles but are delayed in time with respect to each other. The observed delays are smaller for higher energy electrons and larger for greater separations in local time. As an example, the measured delays for 50, 150, and 400 kev electrons on January 11, 1967, when the local-time separation was 110° are 26, 13–17, and 5 minutes, respectively. The observed delays are consistent with newly created electrons being produced in a region near local midnight. These newly produced electrons then gradient drift past the two satellites. The production region is shown to be 30°–60° in width and about 4 RE in depth.