Characteristics and Distribution of Some Radiation Parameters over Nigeria

Abstract

This study examined the distribution and characteristics of Surface Solar Radiation Downward (SSRD), sunshine duration, cloudiness index, relative humidity, temperature, and wind speed from the archive of the NASA Power project between the years 2010 and 2020 over Nigeria using 37 stations. The datasets were subjected to monthly and seasonal analysis over three climatic zones in Nigeria. The results show that the SSRD of the Sahel is generally higher than that of the Savannah and Guinea Coast. Sunshine duration was found to increase seasonally and from south to north. From the extreme edge of the coastal region in the southern part of Nigeria to its far northern region, the mean sunshine duration hour increases northward from about 2075 hours over the coastal region of the south to about 3525 hours in the north. Relative humidity fluctuates between 70-90%, which peaks in August and declined back to its minimum (70%) in December. Observed over all seasons, relative humidity decreases northward from the far south near the Atlantic Ocean to the far north of Nigeria. This is in opposition to the pattern of 2m temperature observed, that is, the 2 m temperature spatial pattern increases from the south to the north. In terms of sky conditions classification, over Nigeria, the cloudiness index is generally less than 0.45. Over the Guinea Coast cloudiness index is observed to be higher than in Savannah and the Sahel zones in all the months with the lowest index of 0.42 in March and the highest index of 0.45 in September. However, the northeastern part of Nigeria is observed to be majorly cloudier in JJA and SON seasons than the far southern region of the country. However, wind speed is observed to be significantly lower than 2.7 m/s over the Guinea Coast compared to other zones. Relatively high and strong winds were noticed to be widespread over the extreme part of the northeastern and northwestern parts of Nigeria in all the seasons, making the region more suitable for wind energy generation.