CRRES electric field data during substorms have been analyzed to investigate intense electric fields in the inner magnetosphere associated with dipolarizations. Substorm injections during 13:00-15:00 UT on 7 March 1991 exhibit many large-scale electric fields and short-duration electric field spikes. Large-scale electric fields with durations of ∼1 min are identified as spatial structures associated with the region 1 field-aligned currents. Amplitudes of electric fields reach 30 mV/m with a high correlation with variations of the magnetic field, and the Poynting fluxes are directed toward the ionosphere with magnitudes of more than 0.5 mW/m2. 16-Hz high-resolution data show intense electric field spikes with amplitudes of ∼100 mV/m with durations of ∼1 s. Most of the spikes are electromagnetic with Poynting fluxes of ∼0.1 mW/m2 directed toward the ionosphere. The electric field spikes are identified as right-handed whistler waves with a size of ∼1000 km with frequencies just below the ion cyclotron frequency. A nearly simultaneous measurement by the DMSP-F9 satellite shows intense plasma flows with durations of 1 s and inverted-V electron precipitation. An estimation of the wave and particle energy fluxes shows that about half of the Poynting flux of the electric field spikes is consumed accelerating auroral particles, and 1% of the Poynting flux drives the fast plasma flows at the ionosphere. It is suggested that the electromagnetic spikes provide sufficient energy for auroral particle acceleration.
ASJC Scopus subject areas
- Space and Planetary Science