Estimation of Daily Global Solar Radiation with Measured Meteorological Data in Xining, China

Solar radiation is a very important and major variable in crop simulation models. However, it is measured at a very limited number of meteorological stations worldwide. In this study, with Xining station, China, as a case study, 9 models were calibrated and evaluated using the meteorological data from 1959 to 2000 for estimating daily global solar radiation. The best results were derived from models 1-4, which used sunshine hours as the predictor. Temperature-based models (models 7-9) provided less accurate results. Therefore, we proposed a strategy to select an optimal method for calculating daily global solar radiation: (1) when sunshine hour data are available, use models 1-4; (2) when only temperature data are available, use models 7-9; and (3) when any meteorological data are not available, use models 5 and 6. Although these models were based on the metrological data of Xining station, they could be applied to other regions with similar meteorological conditions in China after calibration.