Study of equatorial plasma bubbles meridional development over Brazilian sector using ground-based GNSS receivers, COSMIC-2 GNSS RO, and Nasa Gold Satellite data

Abstract

Equatorial Plasma Bubbles (EPBs) are large scale irregularities that occur in the ionosphere under particular electro-dynamical conditions during the sunset to evening period. It is well known that the rapid uplift of the evening equatorial F layer (E×B drift) and the Rayleigh-Taylor instability are the main mechanism by which the EPBs are initiated. The most challenging aspect in EPB prediction now lies in understanding EPBs seeding process and its day-to-day variability. In this sense, a uniform trans-equatorial meridional wind could inhibit the EPBs development or force them to become "fossil". During the "fossil" stage, the EPBs may drift under the influence of background neutral winds and present an asymmetric meridional development with respect to the geomagnetic equator. The role of trans-equatorial wind on the EPBs development has been the subject of a few previous investigations, with no definitive answers. Therefore, this postdoctoral project proposes to study the EPBs meridional development over Brazilian sector using ground-based Global Navigation Satellite System (GNSS) receivers, COSMIC-2 GNSS Radio Occultation (RO), and NASA GOLD satellite data, for the period of 2012 to present. The present project will be the first to focus specifically on a) how thermospheric transequatorial meridional winds can decrease the EPBs linear growth and suppress the EPBs nonlinear growth into topside bubbles; b) the relation between the thermospheric zonal wind and the longitudinal/local time gradients in the integrated Pedersen conductivity across the solar terminator; c) how the EPBs meridional development varies with longitudes, solar and geomagnetic activities; d) calculate the EPBs characteristics (e. g., propagation direction, drift velocity, latitudinal extension, reverse "C" shape, width, and bifurcations); and e) how wave type oscillations (e. g., gravity waves) can affect the EPBs growth rate and its day-to-day variability. (AU)