Airglow Studies on the Ionosphere Dynamics over Low Latitude in Brazil

摘要

Certain features are presented of the ionosphere dynamics over Cachoeira Paulista, Brazil, based on recent photometric observations of OI 6300 A emission, and ionosonde data, both taken at that site. The photometer scanned the geomagnetic meridional plane in a zenith angle range of 75 S to 75 N. Remarkable wavelike structures in the airglow intensity were observed in the premidnight period, which propagate from north to south (poleward) at an average speed of about 240 (+ or -) 70 m/s, assuming the emitting layer to be at an altitude of 250 km. These disturbances had wavelength of a few hundred kilometers and were associated with spread F echoes in the ionograms. A discussion is made on the possible source of the poleward propagating airglow disturbances. It is argued that these are possible manifestations of the vertical propagation of plasma bubbles over the magnetic equator.