Magnetospheric configuration and energetic particle effects associated with a SSC: A case study of the CDAW 6 Event on March 22, 1979


  • B. Wilken,

  • D. N. Baker,

  • P. R. Higbie,

  • T. A. Fritz,

  • W. P. Olson,

  • K. A. Pfitzer


Three geostationary satellites, GEOS 2, 1976-059, 1977-007, located near noon, near midnight, and 0400 LT, respectively, observed the global energetic particle signatures produced by the storm sudden commencement (SSC) at 0826 UT on March 22, 1979. The SSC-induced magnetopause compression generated a steplike wave which traversed the magnetosphere within 2 min. The associated induced electric fields substantially altered both particle energies and drift motions. Local observations of spectral distributions at all longitudes are compared with predictions from a simple model, thus allowing some inference on the radial properties of the particles' energy distribution function. The nonadiabatic compression during the SSC modified existing drift orbits of energetic particles and increased drift shell splitting. Field-aligned pitch angle distributions for electrons and protons appearing at and around local midnight are related to an intersection of drift shells with the inward displaced magnetopause. These observations are used to detect displacements of the magnetopause to standoff distances between 6.6 and 9 RE with satellites located in the midnight sector. A combination of the present multipoint measurements with the Olson-Pfitzer dynamic magnetospheric model allows quantative conclusions on, for example, energetic particle drift times in disturbed fields and the magnetopause standoff distance and its relation to both pitch angle cutoffs and dispersive flux dropout events. The availability of this model made it possible to use particle drift as a medium for remote sensing techniques over global distances.