# Thermospheric Neutral Wind Measurements and Investigations across the African Region--A Review
## 4 Measurements of Zonal Wind Magnitudes and Directions  
The typical scenario for the zonal thermospheric winds is that they are mostly eastward, especially before midnight. The zonal winds are generally fast in the early evening hours, and peak around \(\pm\)3 h of midnight. Then they slow down thereafter, and occasionally develop weakly in the westward direction a few hours prior to sunrise. In the equatorial region of East Africa, [PERSON] et al. (2017) [27] reported no occurrence of westward motions of the monthly averaged winds throughout the nights for the entire periods of their study (November 2015-April 2016). In equatorial West Africa, [PERSON] et al. (2021) [4] reported a few cases of westward wind motions during the months of June 2016 (05:00 to 06:00 LT) and January 2018 (06:00 LT). The westward wind magnitude in June reached \(\sim\)100 m/s, while the value in January was \(\sim\)20 m/s. The average monthly winds were predominantly eastward during the rest of the 9 months that they investigated. In mid-latitude Morocco, [PERSON] et al. (2015) [17] reported westward wind motions during the months of May (02:00 to 04:00 LT), June (02:00 to 04:00 LT), July (03:00 to 05:00 LT), August (03:00 to 05:00 LT), and September (03:00 to 05:00 LT). The reported westward wind magnitudes were generally less than 50 m/s. [PERSON] et al. (2017) [23] and [PERSON] et al. (2020) [26] reported no occurrence of the westward wind during winter, and their noticeable occurrence during summer. The averaged westward magnitudes were typically less than 50 m/s, except during 03:00 LT of the 2016 summer when the value reached \(\sim\)100 m/s. These results are similar and in agreement with the report of [PERSON] et al. (2015) [17]. The zonal winds also show dependence on solar activity. [PERSON] et al. (2020) [26] presented averaged zonal wind measurements for the years 2014, 2015, and 2016 (mean solar activity decreases in that order). The results showed that the eastward zonal winds were typically faster in 2014, slower in 2015, and slowest in 2016, indicating that the eastward zonal winds are faster during years of higher solar activity. Similar results were found  
Figure 4: Meridional winds in Nigeria for March 2016 to January 2018. The red plots represent the FPI measurements, while the black plots represent corresponding HWM-14 predictions. The vertical error bars indicate the standard deviations of the observations. Adapted with permission from Ref. [4]. 2021, [PERSON] et al. by [PERSON] et al. (2015) [17], who showed that the monthly means of the eastward zonal winds for days with higher solar activity were greater than values of the means for days in the same months with lower solar activity. In [PERSON] et al. (2020) [26], the switch from the eastward-to-westward direction of the zonal wind in summer was particularly observed to occur earlier in 2015 and 2016 (around 02:00 LT) than in 2014 (around 03:00 LT), indicating that the switch happens later for the year of higher solar activity. Figures 5-7 represent some plots of the zonal winds in Morocco, South Africa, and Nigeria, respectively. Geomagnetic activity can also significantly alter the climatology of wind patterns. In fact, due to high-latitude heat input, large scale storm-induced atmospheric waves that propagate to low latitudes and into the opposite hemisphere are created. As a result, the storm-induced westward zonal winds and equatorward meridional winds add and modify the quiet-time background wind circulation. The results of [PERSON] et al. (2018) [25], for example, revealed that there was conspicuous westward motion of the wind in Morocco during the geomagnetic storm of 27-28 February 2014, reaching a peak magnitude of ~75 m/s (when averaging the east and west look measurements) around 01:00 LT of the night. The impact was clearly distinct because the westward peak was reached at a time around the middle of the night, and the magnitudes returned thereafter to expected values towards sunrise.