A general model for estimation of daily global solar radiation using air temperatures and site geographic parameters in Southwest China

Estimation of daily global solar radiation (Rs) from routinely measured temperature data has been widely developed and used in many different areas of the world. However, many of them are site specific. It is assumed that a general model for estimating daily Rs using temperature variables and geographical parameters could be achieved within a climatic region. This paper made an attempt to develop a general model to estimate daily Rs using routinely measured temperature data (maximum (Tmax, °C) and minimum (Tmin, °C) temperatures) and site geographical parameters (latitude (La, °N), longitude (Ld, °E) and altitude (Alt, m)) for Guizhou and Sichuan basin of southwest China, which was classified into the hot summer and cold winter climate zone. Comparison analysis was carried out through statistics indicators such as root mean squared error of percentage (RMSE%), modeling efficiency (ME), coefficient of residual mass (CRM) and mean bias error (MBE). Site-dependent daily Rs estimating models were calibrated and validated using long-term observed weather data. A general formula was then obtained from site geographical parameters and the better fit site-dependent models with mean RMSE% of 38.68%, mean MBE of 0.381 MJ m−2 d−1, mean CRM of 0.04 and mean ME value of 0.713.

► Models using temperatures for daily Rs estimation were validated in southwest China.
► The best performed model was determined on the basis of RMSE%, MBE, CRM and ME.
► A general model was developed using the best model and site geographical parameters.
► RMSE% and MBE of the general model fell well within the ranges found in other studies.