A hybrid model for estimating global solar radiation

In view of the site-dependence of Angstrom correlation, this study developed a hybrid model to estimate global radiation H. Unlike Angstrom correlation H = (alpha + betaS/S(0))H(0), this model suggested that H = (a + b S/S(0))H(b) + (c + d S/S(0))H(d), H(b) and H(d) are effective beam radiation and effective diffuse radiation, which imply latitude, elevation and seasonal effect on radiation. H(b) and H(d) are calculated by an arithmetic model derived from spectral model. The hybrid model was designed for estimating monthly mean daily global radiation with hourly-recorded bright sunshine time, and its applicability was verified at observatories in Japan. (C) 2001 Elsevier Science Ltd. All rights reserved.