Impacts of cloudiness on near surface radiation and temperature in Nigeria, West Africa

Abstract

This study investigates impacts of cloudiness on surface radiation budget and temperature from 1983 to 2018 in Nigeria, West Africa. The National Aeronautics and Space Administration meteorological datasets were used to achieve this objective. Net radiation (R) increased latitudinally from the coast to the inland areas. The least value of R was obtained in wet season which coincided with the period when cloud cover was at its optimal. We obtained significant decreasing trends (− 0.110 to − 0.536 Wm −2 year −1) in R but significant increasing trends in cloud cover in most parts of the region. Under clear-sky conditions, however, significant increasing trends (0.256-0.807 Wm −2 year −1) in R were obtained. Annual mean temperature showed significant upward trends under all-sky (0.009-0.059 °C year −1) and clear-sky (0.019-0.072 °C year −1) conditions. Furthermore, significant negative correlations (− 0.70 ≤ r ≤ − 0.95) were obtained between monthly values of cloud cover and R over the country. However, r values for cloud cover and temperature were positive over Sahel (r ~ 0.65) but negative over Guinea (r ~ 0.45); both significant at p < 0.05. Changes in R were accounted for by 21 to 26% variations in cloud cover, while fluctuation in temperature was explained by about 14% variation in cloud cover over Sahel region at p < 0.05. Our results revealed that the surface radiation budget was significantly perturbed by variations in cloudiness which resulted in net cloud-radiative cooling (− 30 Wm −2) over Guinea but warming over Savannah (25 Wm −2) and Sahel (50 Wm −2) zones.