关键词: 日照时数, 总云量, 华南, 线性趋势, 变化特征

Abstract:

Based on the annual sunshine duration data from 110 observational stations during 1961-2008 in South China，the climatic changes and the spatial temporal features of sunshine duration were studied by using statistical diagnostic methods，including linear regression analysis，MannKendall test，power spectrum function and the computation of trend coefficients. The results show that the annual mean sunshine duration shows a decreasing trend from South China to North China in the past 48 years.The highest center is located in Nanning of Guangxi（2552 h）and the lowest center in Jingxiu of Guangxi（1172h）.The annual sunshine duration has declined at a mean rate of 4.09 h/a，which is higher than that of China. The changes of annual sunshine duration show significant 22 year and 11 year periods，with an abrupt change in the late 1970s. The trend of sunshine duration in South China has a remarkable regional difference. Decreasing trend of sunshine duration is obvious in most part of South China. There are three decreasing centers, located in Shenzhen of Guangdong（-12.86 h/a），Chengmai of Hainan （-12.85 h/a）and Hengxian of Guangxi（-11.85 h/a）respectively. The distribution of the annual mean sunshine duration is in accord with that of total cloudiness，but the secular trend variation of sunshine duration is different from that of total cloudiness.In most part of Guangdong, the total cloudinessincreases and the sunshine duration decreases obviously.

Key words: sunlight duration, total cloudiness, South China, linear trend, change characteristics