| Solar radiation is primary energy source for all the biological organisms on the earth and one of the most important natural factors concerned about in many scientific fields. However, compared to temperature and precipitation, its measurements are rather deficient in China. Consequently, it needs to be estimated from routinely meteorological variables.Based on the observational daily solar radiation and other data of meteorological elements including sunshine hour and temperature of 67 stations in China from 1961 to 2000, the spatial and temporal distribution characters and the long-term changing tendency of the total radiation were studied. Considered the physical mechanism that influences the change of solar radiation, models were established for assessment of daily solar radiation. The models include two independent variables of percentage of sunshine and diurnal temperature range. The results are as follows:The value of total solar radiation in northwest is larger than that in southeast in China. Its distribution is different according to season and area.The trend of total radiation is decreased by the average range of 1.9682%/10yr over the past 40 years. The decline is largest in winter, followed by summer.Except for Qinghai-Tibet Plateau, multiple correlative coefficients of the other seven models all surpass 0.84.The annual mean absolute error is 2.1587 MJ·m-2·d-1 and the mean relative error is 15.6854% of the eight areas.In view of the seasonal differences, models were established for different seasons. Through analysis on the modeled results, we found that it is necessary to use separate model in spring and seasonal models in Yunnan Province.Through examination by the data of different years, it could come to a conclusion that the models developed in this paper are effective and feasible in assessment of daily solar radiation in all periods.
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