Diurnal Variation of Net Radiation at Ile-Ife, Nigeria

Using a four-component net radiometer, model NR01, hourly averaged net all-wave radiation data spanning 3-year period (2010 – 2012) at Ile-Ife (7.52 oN, 4.52 oE), Nigeria has been analyzed in this study to discuss both the diurnal and seasonal variations. From the dataset, hourly maxima of the net radiation occurred at 14:00 hr local time (GMT+1), the values of which increased considerably from 337.6 ± 146.4 Wm-2 in July which is peak of the wet season to 441.7 ± 82.4 Wm-2 in March, end of the dry season. April and October, both of which mark beginning and end of raining season at Ile-Ife have recorded the highest values of 584.7 Wm-2 and 612.2 Wm-2 respectively. The intra/inter-seasonal variations observed in the hourly mean values of the net radiation is mainly due to fluctuations of the cloudiness and humidity. There is a net radiative heating at the surface which annual trend follows a bimodal distribution. The data represents the most consistent and detailed information available for a tropical location in West Africa to date.