Coincident observations of equatorial bubbles by ROCSAT-1 and a ground imager at southern Taiwan

Abstract

On the night of 19 March 1999, ROCSAT-1 orbiting at ∼ 600 km altitude observed several small ion depletions of equatorial spread F events at various longitudes. At the southern Taiwan on Mountain A-Li, a 6300 Å airglow imager also observed bubble events at ∼ 300 km during the night. Coincident observations of the depletion event by the two instruments near 13:39 UT (21:39 LT) were analyzed. Mapping the ROCSAT-1 orbit along the magnetic flux tube to a lower altitude where the 6300 Å airglow images were recorded, a good correlation between the image intensity and the ion density structure inside the bubble was obtained. Comparable eastward drifts of the bubble at 300 km and at 600 km within the same magnetic flux tube illustrate the elongated nature of the bubble along the magnetic field.