Plasma bubble zonal drift characteristics observed by airglow images over Brazilian tropical region

Abstract

Using airglow images observed at São João do Cariri (7.4°S, 36.5°W; dip angle: -11°S) from September 2000 to April 2007, plasma bubble zonal drifts for ninety-seven geomagnetically quiet nights (Dst index higher than -30 nT) were calculated. The plasma bubble eastward averaged drifts presented an increase from 18:00 to 22:00 local time (LT), and followed by a deceleration. The plasma bubbles observed during high solar activity were faster after 22:00 LT. Eastward drifts observed during the summer, after 21:00 LT, were higher than drifts observed during the equinox months. Few nights had plasma bubble eastward drifts higher than 100 m/s and almost all bubbles disappeared after 02:00 LT. Averaged zonal drifts observed between -9.5 and -5.5°S were almost constant, primarily, around 23:00 LT. © 2011 Sociedade Brasileira de Geofísica.