Simultaneous observations of equatorial F-region plasma depletions and thermospheric winds

Simultaneous observations of the OI 630.0 nm nightglow emission using an all-sky imaging system, and thermospheric winds and temperatures using a Fabry-Perot interferometer at 630.0 nm, have been recently conducted at Cachoeira Paulista (22.7 degrees S, 45.0 degrees W, dip latitude 15.8 degrees S). The all-sky imaging observations of the OI 630.0 nm nightglow emission, which arises from the O(2)(+) ionospheric dissociative recombination process, are used to monitor the morphology and dynamics of transequatorial ionospheric plasma bubbles in the height range of the nightglow emissions. In this paper we present simultaneous observations from these two instruments obtained in April and August 1991, in which some nights showed the presence of ionospheric plasma bubbles. These observations are also complemented by ionospheric sounding data obtained at the equatorial station Fortaleza (3.9 degrees S, 38.4 degrees W, dip latitude 3.7 degrees S). Significant features of the morphology and time evolution of the plasma depletions as seen through the OI 630.0 nm emission images and possible influence of the thermospheric winds on the generation of the plasma irregularities are analyzed and discussed. (C) 1997 Elsevier Science Ltd.