Application of Kriging Technique for the Construction of Clearness Index Maps for Some Selected Tropical Stations in Nigeria

Authors: Ojo, M.O.
Department of Physics, Adeyemi College of Education, Ondo

In this study, bringing technique was adopted in the construction of clearness index maps for some selected tropical stations in South Western Nigeria. Characterization of solar radiation was carried out to assess the feasibility of solar energy utilization. Clearness index, diffuse ratio and diffuse coefficient are computed from acquired data of global solar radiation, temperature and relative humidity which are obtained from the Satellite derived data from National Aeronautical and Space Administration (NASA). A characterization of the sky conditions over the stations based on the calculated clearness index KT values for the eleven years (January 1995 - December, 2005) were presented. Aaron monthly irradiance data given as a mean monthly radiation are transformed into monthly clearness index values through the application of the Bringing Technique. Finally, monthly mean clearness index contour maps were constructed for the stations for the selected years using Kriging method. The results of the research work revealed that the clearness index varies with the geographical location and period of the year. The implications of the results on the effective utilization of the solar energy are subsequently discussed.