Multispacecraft observations at the compressed magnetopause following the 13 July 1982 interplanetary shock

Abstract

The global magnetospheric compression on 13 July 1982 following the arrival of an interplanetary shock was observed by a number of spacecraft. Energetic electron and ion data as well as magnetometer measurements on three geostationary spacecraft operating on the frontside of the magnetosphere are used to obtain information about the shape of the magnetopause during times of enhanced solar wind dynamic pressure. The deviation from the average shape of the uncompressed magnetopause to a more circular shape found occasionally during this event is discussed in terms of the unusually high thermal pressure in addition to the enhanced kinetic pressure of the streaming solar wind plasma. Unidirectional distributions of energetic (up to ∼300 keV) ions found at the magnetopause outside the last closed field line for a period of more than 1 h are interpreted as field aligned streaming of ions indicative of the depletion of newly reconnected field lines at the frontside of the magnetosphere.