Vol. 13(2), pp. 8-15, 30 January, 2018 DOI: 10.5897/IJPS2017.4703 Article Number: 81CDF5D55935 ISSN 1992 - 1950 Copyright ©2018 Author(s) retain the copyright of this article http://www.academicjournals.org/IJPS International Journal of Physical Sciences Full Length Research Paper High-latitude thermospheric zonal winds during low solar activity period Sivla W. T.*, Ugonabo O. J. and Okoro E. C. Department of Physics and Astronomy, University of Nigeria, Nsukka, Enugu State, Nigeria. Received 2 December, 2017; Accepted 18 January, 2018 Changes resulting from the cyclical nature of the sun’s energy output result to variations in thermosphere-ionosphere system parameters. The prolonged low solar activity period of solar cycle 23 provides an opportunity to study the thermosphere-ionosphere system parameters when the sun was at its ground state. The CHAMP satellite has provided wind data that can be used for investigation of neutral thermospheric parameters such as zonal winds and density. Using zonal wind data from 2006 to 2008 generated from CHAMP accelerometer readings using an iterative algorithm, the diurnal variation of averaged zonal thermospheric winds in the high latitudes (70 - 80°N) has been investigated. In the analysis we grouped the data into four seasons; the March and September equinoxes, and the June and December solstices. The wind data is binned into local time bins and averaged to find the hourly mean speeds. The results reveal maximum eastward and westward wind speeds going above 150 m/s for each of the seasons considered. Of particular interest is the observation that despite the expected complex behavior resulting from the expected magnetospheric inputs, the diurnal patterns are similar to those obtained in the mid-latitudes in an earlier study with data from this algorithm. Due to likely errors arising from the longitudinal effects of mixing composite solar times, there is need for simultaneous measurements in the high latitudes. Key words: CHAMP satellite, high latitude, solar activity, thermosphere. INTRODUCTION The thermosphere is the first layer of the earth’s atmosphere that receives the sun’s ultraviolet (UV) and extreme ultraviolet (EUV) radiations. These radiations ionize the neutral molecules that make up the thermosphere forming an embedded ionized region; the ionosphere. The thermosphere is coupled to the ionosphere by the interactions between the ionized and neutral species. A thorough understanding of thermospheric variability is important in establishing the state of the earth’s upper atmosphere. Thermospheric perturbations can arise from external forcing sources to which the thermosphere is coupled. The earth’s thermosphere-ionosphere system is coupled from above by interactions with incoming solar radiations and magnetospheric electric fields, and coupled to layers below by tides, gravity and planetary waves as shown in *Corresponding author. E-mail: william.sivla@unn.edu.ng. Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License