Analysis of equatorial F-region vertical neutral winds from Brazil FPI observations

Abstract:

An accurate description of vertical neutral winds in the thermosphere is essential to understand the upper atmosphere variations. Although the vertical winds are typically small, significantly smaller than typical zonal and meridional winds, they can be non-zero under certain conditions. Recent development in observing instrumentation (primarily the Fabry-Perot interferometer (FPI)) now permits substantial progress to be made on specifying this component of the neutral wind vector. In this paper, neutral vertical wind data from Brazil FPI observations at around 240-km altitude during 2009 to 2014 are used for a climatological study of the equatorial vertical wind. This study included examination of the dependence on seasonal, solar, and geomagnetic activity. First, the data have been binned according to the local time, and the seasonal dependence of the local time variation is analyzed. Second, the examination of vertical neutral wind dependency on solar and geomagnetic activity is performed. The correlation of the vertical wind with F10.7, Kp and Dst parameters has also been studied. These results give us an unprecedented view of the behavior of the nighttime vertical wind at low latitudes, which is critical to specifying the dynamics of the upper atmosphere more globally.