INFLUENCE OF THE AURORAL ELECTROJET AND OVAL ON MIDLATITUDE THERMOSPHERIC TEMPERATURES AND MERIDIONAL WINDS

A large geomagnetic storm commenced at 00:00 UT in conjunction with a southward turning of the IMF on September 18, 1979. There was a significant interruption in the development of the ring current between about 03:00 UT and 05:00 UT. But the growth phase re-emerged shortly after 05:00 UT, resulting in major changes in the auroral dynamics. The neutral temperatures showed general enhancements of 100 K to 150 K, consistent with the storm time conditions. The mean temperature was about 1324±164 K. The meridional winds were directed equatorward and they ranged between 30 m/s and 370 m/s. Both the temperature and wind speed showed a rapid and dramatic increase as several substorms occurred in rapid succession and the electrojet moved equatorward for the period between 05:00 and 10:00 UT. The maximum wind speed occurred some 40 minutes earlier than the occurrence of the maximum temperature. -from Authors