Abstract: Variation in the distribution of solar radiation on the earth surface can fundamentally alter characteristics of temperature, humidity, precipitation and atmospheric circulation, and are thus considered important indicators in the evaluation of climate change. In this study, the determination of Angstrom coefficient of a, and b was conducted with the measured global solar radiation datasets from the stations of Hefei and Gushi. Then, the Angstrom formula was used to estimate global radiation based on relative sunshine data at 6 meteorological stations in Huaibei Plain during the period 1959-2015. The spatial variation characteristics of intensity distribution, variation trend and abrupt time of annual and seasonal total global radiation revealed in the past 57 years in Huaibei Plain were analyzed with the methods of linear-trend estimation, Mann-Kendall test and Moving-T test through the Kriging interpolation method. And the periodic variation of total global solar radiation was analyzed by Morlet wavelet analysis. The results showed that the solar radiation in north of the Huaibei Plain was greater than that in south. The annual solar radiations were varied from 4 600 to 5 020 MJ·m-2 in the whole area and the annual average difference of solar radiation between north and south is 200-400 MJ·m-2. In the western part of Huaibei Plain, the solar radiation showed obvious decreasing trend that were significant at the 99% confidence level in the past 57 years while there exist some subtle rising trend during the periods of spring in the eastern part of Huaibei Plain, and summer reaches the maximum decrease. Solar radiation catastrophe appeared mostly in 1980s in the western part of Huaibei Plain with bypass the significant test for at least 95% confidence level, while there basically no catastrophe appeared in eastern regions. The results of the wavelet analysis showed that the whole area of Huaibei Plain had quasi-periods of 29 a (long period) and 17 a (mid-long period). The major and significant periodic in Northern Huaibei Plain were 9-17a while the major cycle in Western Huaibei Plain were 27-30 a and the oscillation intensity of the main period exhibited in the western part of Huaibei Plain was stronger than that in the eastern part. The resource of solar radiation in Northern Huaibei Plain was abundant and stable. The analysis results showed that the decrease of relative sunshine is the main meteorological factor leading to the decrease of total solar radiation, which the variation of relative sunshine is positively correlated with wind speed.
Key words：surface global solar radiation; linear trend estimation; change point; wavelet analysis; Huaibei Plain