What is happening near Sq focus? Original Research Article

Rocket measurements of electron temperatures (Te) in the E region over Kagoshima Space Center, Japan, carried out in a serees of experiments conducted from 1970 to 1988 are analysed in this paper. All the 13 flights whose results are presented here took place around 11 AM, close to the Sq current intensity maximum. Anomalously high electron temperatures associated with large increases of high energy tail electron population were observed whenever the estimated Sq current vortex was very close to the launch site. Such anomalous temperatures were observed only in local winter months. A mechanism for the anomalous heating is proposed based on the solsticial asymmetry of the Sq electric potentials and the resulting field-aligned current that could flow from winter to summer hemisphere.