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Investigation of the variability of night-time equatorial thermospheric winds over Nigeria, West Africa
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  • Daniel Izuikedinachi Okoh,
  • A. Babatunde Rabiu,
  • Qian Wu,
  • Bolaji O S,
  • R. B. Abdulrahim,
  • O. E. Dare-Idowu,
  • Aderonke Adekemi Obafaye
Daniel Izuikedinachi Okoh
Space Environment Research Laboratory

Corresponding Author:okodan2003@gmail.com

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A. Babatunde Rabiu
National Space Research and Development Agency NASRDA,, Abuja, Nigeria
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Qian Wu
National Center for Atmospheric Research (UCAR)
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Bolaji O S
Department of Physics, University of Lagos, Nigeria.
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R. B. Abdulrahim
Centre for Satellite Technology Development, NASRDA,
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O. E. Dare-Idowu
Centre for Atmospheric Research
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Aderonke Adekemi Obafaye
Centre for Atmospheric Research
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This paper examined the variability of equatorial thermospheric meridional and zonal wind speeds at night-time using an optical Fabry–Perot interferometer (FPI) located in Abuja, Nigeria (Geographic: 8.99°N, 7.39°E; Geomagnetic latitude: -1.60). The study period covered 9 months with useable data of 139 nights between March 2016 and January 2018. The hourly zonal wind speed is between 19.33 and 250 ms-1 and that of the meridional wind ranged between 0 and 200 ms-1. These speeds are greater than those reported in other longitudinal sectors, and this could be one of the reasons responsible for reduced EXB drift in this region compared to other regions. Comparison of FPI ground-based measurements with estimates from the Horizontal Wind Model (HWM-14) accurately reproduced the meridional component, but for some departure of ~45 ms-1 in May and June 2016, and January 2018. A very good agreement is observed between the predicted and measured zonal winds speed in the months of 2017. However, the HWM-14 overestimated the zonal wind speed in the early evening values by ~30 ms-1 and underestimated the post-midnight values by a larger factor in December 2017. Hence, this necessitates a call for improvement of the HWM-14 by using newly observed data in order to better characterize the West African sector. The varying zonal winds showed modal periods of 25.9 and 133.5 days, which are quasi 27-days and quasi-terannual periodic variations, respectively. On the meridional wind, oscillatory periods of 133.5 and 23.1 days are seen in year 2016 and 2017, respectively.