Performance of solar radiation models - a case study

Performance of cloud-based (Kasten) and sunshine-based. (Angstrom-Prescott, Garg and Garg, Sivkov) empirical solar radiation models is presented for a lowland and mountain grassland sites. Data sets utilised for the study extended from 1991 to 1994. Adjustable parameters in the models were determined. Observed monthly mean values of solar radiation KJ and those estimated using Kasten model agreed within 2.5% for the lowland site and 13% for the mountain site, while those estimated using Angstrom-Prescott relation agreed with observation within 2.5% for lowland site and 3.4% for the mountain site. The incorporation of air mass, latitude and water vapour terms into Angstrom-Prescott relation did not significantly improve estimates of K down arrow. In general, Angstrom-Prescott as well as Garg and Garg models yielded the least RMSE for the study sites. (C) 2001 Elsevier Science B.V. All rights reserved.