Solar-terrestrial disturbances of June-September 1982, 4

A new 50-MHz Doppler radar with a mini-computer for real-time data processing and radar control was installed at Syowa Station, Antarctica in February 1982. Severe geomagnetic disturbances occurred at about 00 h UT, 14 July 1982. Then the magnetic H component decrease of about 4200 nT was observed at Syowa Station, and that of about 630 nT was observed at Kakioka Magnetic Observatory in the midlatitude. 50-MHz backscatter echoes were received on 13 - 14 July 1982 during a substorm growth phase, so the rough estimates of the Doppler velocity during this period were obtained. In this paper the Doppler spectra are discussed on the following three stages: SSC onset, substorm main phase and recovery phase. On the hypothesis of spatially homogeneous plasma flow, we determined a large-scale electric field by combining the drift velocities along the radar beams. It appeared that the E region electric field was larger than 30 mV/m in the main phase of this substorm. (author)