Simultaneous DMSP and CRRES observation of broadband electrons during a storm-time substorm on March 25, 1991

Broadband electrons observed by the DMSP satellites during storm-time substorms are characterized by an unusually intense flux of precipitating electrons over the broadband energy range from 30 eV to 30 keV near the equatorward edge of the auroral oval (Shiokawa et al., 1996; 1997). During the broadband electron event observed by the DMSP-F9 satellite at 21 MLT on March 25, 1991, the CRRES spacecraft was at a geocentric distance of 6.3 R(E) and in the same local time as that of DMSP. The CRRES satellite observed 1) a large enhancement of field-aligned electron flux, 2) highly turbulent electric fields up to 10 mV/m, 3) intense west-ward excursion (~100 nT) of magnetic field (suggesting intense field-aligned current generation) in a highly tail-like field configuration, 4) large O⁺ energy density, and 5) intense low-frequency (below 300 Hz) electrostatic waves. We discuss possible production mechanisms of broadband electrons on the basis of these observations.