Abstract: The global solar radiation(Rs) is of great significance in the fields of agricultural production system, hydrometeorological research and clean energy development. Due to the complicated topography and various climate in Sichuan province, the distribution of global solar radiation is uneven. In order to explore the most suitable Rs estimation models for different zones of Sichuan, Sichuan was divided into three solar radiation zones in this paper (zone I: western Sichuan plateau, zone II: eastern Sichuan basin, and zone III: southwest Sichuan mountain) for research. Zone I(Ganzi and Hongyuan stations) has low temperature, sufficient sunshine and strong solar radiation; zone II(Chengdu, Mianyang and Luzhou stations) has high relative humidity, short sunshine duration and low radiation; zone III(Emeishan and Panzhihua stations) is abundant in solar radiation resources, but the air temperature and humidity vary greatly within the zone. In three solar radiation zones, based on the meteorological data from 1994 to 2016, the applicability of six Rs estimation models were evaluated under three weather types(sunny, partially cloudy and cloudy), and the simulation effect of combined models based on weather types in different zones were analyzed. The results showed that: (1) the empirical models performed well in Sichuan province(the coefficient of determination R2 ranged from 0.554 to 0.934, P<0.001). The most accurate simulation model in zone I was sunshine-based model A−P with mean absolute error (MAE) 2.210±0.714MJ∙m⁻²∙d⁻¹. The hybrid model Chen was the best in zone II (MAE was 1.510±0.027MJ∙m⁻²∙d⁻¹) and zone III (MAE was 1.510±0.027MJ∙m⁻²∙d⁻¹). (2) The statistical performance of the six models under three weather types in Sichuan showed sunny>partially cloudy>cloudy. The sunshine-based models(A−P and Ba models) could better simulate the Rs in sunny days, while the hybrid models(Chen and Ab models) had higher accuracy in simulating partially cloudy and cloudy days. The A−P(the global performance indicator GPI = 0.850), Ab(1.294) and Ba(0.862) models were the best models to simulate Rs of zone I in sunny, partially cloudy and cloudy, respectively. The A−P(GPI = 0.381), Chen(1.358) and Chen(1.742) models were the best models to simulate Rs of zone II under three weather types, respectively. The Chen model was the best model to simulate Rs of zone III in sunny, partially cloudy and cloudy with GPI 0.204, 0.857 and 0.526, respectively. (3) The Rs combined models(Mnew) based on weather types had the best simulation accuracy in each zone(GPI were 0.558, 0.582 and 0.134 in 3 zones, respectively). Therefore, it is recommended to use the Rs combined models based on weather types to estimate Rs in Sichuan province.

Key words: Global solar radiation(Rs) models, Sichuan province, Solar radiation zones, Different weather types, Applicability evaluation