Thermospheric Wind Observation using Fabry-Perot Interferometers at Arecibo and Nigeria

Thermospheric neutral wind is one of the drivers that change the behaviour of ionosphere by creating dynamo electric field that can influence plasma instabilities (Kelley, 2009) which in turn inhibit radio wave propagation through the region. The impact of the thermospheric winds over equatorial Africa ionosphere is just beginning to be addressed. In order to investigate this wind behaviour over African sector, we used thermospheric wind data obtained from Fabry perot interferometer (FPI) recently installed at Space Environment Research Laboratory, Center for Atmospheric Research, National Space Research and Development Agency (NASRDA), Nigeria (9.06^oN, 7.5^oE; 1.49^oS geomagnetic latitude), and compared with that of Arecibo, Puerto Rico (18.4^oN, 66.7^oW, 29.2^oN geomagnetic latitude) over South America sector by monitoring wind induced Doppler shift in the nightglow emissions at 630.0nm. The available data used for the analysis are December 9, 2016 a geomagnetically disturbed day with kp = 5; September 7 and December 25, 2016 obtained on quiet days with kp = 2 and 3 respectively. For all the nights considered, the meridional wind speed direction at Arecibo was poleward for major part of the nights with a maximum speed of 200m/s before midnight. Also, in Abuja, the meridional wind speed was poleward on December 9, 2016 with a maximum of 200m/s at 1930LT but on September 7, 2016 a reduced poleward wind speed of 50m/s was observed. The wind speed was equatorward on December 25, 2016 from post sunset till midnight with a maximum of 180m/s and reverses poleward towards sunrise. Similarly, the zonal wind speed at Arecibo was majorly westward reaching a maximum speed of 150m/s at 2300LT. For Abuja, a westward wind direction was only observed on December 9, 2016 with a maximum of 190m/s at 1800LT. The zonal wind speed was eastward for September 7 and December 25, 2016 with a maximum of 150m/s at 2000LT. In summary, the same thermospheric wind direction was observed on December 9, 2016 for both stations, a varying wind movement that are opposite in directions were observed on September 7, 2016 and December 25, 2016. NCAR Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) was compared with the observations. TIEGCM underestimated the observational thermospheric wind data at post sunset while a better performance was seen after midnight.