Aurora observation using the Syowa Station 50-MHz Doppler radar

A new 50-MHz Doppler radar with a minicomputer 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, July 14, 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. The 50-MHz backscatter echoes were received on July 13-14, 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, a large-scale electric field is determined 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.