Counter equatorial electrojet currents in the Indian zone

Abstract

The paper describes the phenomenon of afternoon depression of the geomagnetic H field on quiet days near the magnetic equator in the Indian zone. These events occur most frequently around 1600 solar hr and are localized in longitude; sometimes, not seen at stations separated by even 2 hr LT. The geomagnetic disturbance tends to decrease or destroy the identity of the phenomenon. The latitudinal extent of these events is confined to the equatorial electrojet region. The events do not seem to be caused mainly by the Moon, but their occurrences are modified by the lunar age, being most frequent around new and full Moon. These events are associated with the disappearance of the q type of E_s over the Equator for periods during which the H field is below the night-time level. The currents responsible for these events flow westward in the E-region and are within few degrees centred near the magnetic equator.