ISEE-1 AND GEOTAIL OBSERVATIONS OF LOW-FREQUENCY WAVES AT THE MAGNETOPAUSE

Observations of waves at frequencies below similar to 200 Hz obtained near the magnetopause are presented. For one case identified in the ISEE 1 data as a period when steady state reconnection was occurring, there were waves below the lower hybrid frequency with amplitudes up to similar to 7 mV/m. Intense low-frequency waves with amplitudes up to similar to 20 mV/m at the subsolar magnetopause have also been observed by the Geotail electric field instrument. In some cases, large spiky fields were embedded in the waves. The waves observed by ISEE 1 and Geotail were large enough to provide the dissipation required for reconnection to occur.