Discussion on the Variation Characteristics of the Total Solar Radiation in Jiangxi Province Utilizing Penman Equation

Based on the annual total solar radiation and related meteorological data of monitoring stations of Ganzhou and Nanchang from 1960 to 2000, the annual total solar radiation of the two stations were calculated with six net long wave radiation formulas combinated with Penman equation. The Method of Absolute Errors (MAE), aiming at estimating the total solar radiation in the region, was proposed with the annual weight coefficients of MAE. The annual total solar radiation of the other 76 stations in Jiangxi Province was calculated with this method. Through the analysis of the temporal-spatial distribution and the trend of the annual total solar radiation of the province, the authors found that: (1) During 1961 to 2000, the value of the total solar radiation in the most parts of Jiangxi Province was 3800-4400 MJ·m-2·a-1. The total solar radiation was high in the southeast region, where there was a large value center. The west part had a lower value than the other parts of the province; (2) For the whole province, the total solar radiation decreased in the past 40 years with the ratio of 143.70 MJ·m-2·(10 a)-1. Among the total 78 stations, 63 stations passed the 0.05 significance level and six stations presented an upward trend. The total solar radiation showed a relatively larger decline in the northern and southern region than in the center part. And there was a low value center on the east side of Poyang Lake.