BEHAVIOR OF THE [OI] 6300 A EMISSION AT THE MAGNETIC EQUATOR AND ITS RELATION TO THE VERTICAL EXB PLASMA DRIFT VELOCITY

Observations of the local time dependence of the [OI] 6300 Å zenith intensity made with a filter photometer at Natal, Brazil, near the magnetic equator, are presented, together with the local time behavior of theoretical 6300 Å intensities calculated using a realistic dynamic computer model of the tropical ionosphere. It is shown that the observed local time variation of the 6300 Å emission is controlled by the local time behavior of the vertical E × B plasma drift velocity at the magnetic equator. The typical 6300 Å enhancement which occurs near midnight gives an indication of the magnitude and time of reversal of the vertical plasma drift velocity. © 1979.