Fractal research of rainy day changing trend from Tibetan Plateau to Eastern China
青藏高原至中国东部年雨日变化趋势的分形研究

The precipitation climatic change includes the changes of the rainfall and the rainy days.Rainy day change is an important constituent of the precipitation climatic change.Under the background of the temperature rising and the climatic warming,how will the rainy days be able to change? This problem belongs to one of the important contents on global climatic change research.The author studied the regional change,the tendency change and the future change of the annual rainy days of China.Using the rainy day data from 1951 to 2002 at 194 meteorological stations of China,the author studied and forecasted climatic change tendency of annual rainy days in five regions of China with the basic principle of the fractal theory,R/S analytic method.The study indicates that,there is a similarity between future change tendencies of annual rainy days in five regions with that of the past 50 years.In order to make an in-depth study of the future change of rainy days,this study designed two items of Hurst Index experiment and inferred the changing tendency, the transition and the sudden change of rainy days with the corresponding relation between two experimental results and the annual changing tendency of the rainy days.The result indicates that the annual rainy days have the completely consistent tendency to reduce in five regions of China,but the change of rainy days shows a remarkable regional differential characteristic.The rainy days will reduce 6.8 days every ten years in the next ten years in the north of Eastern China and 5.9 days in the south of Eastern China.The reduction of that of Sichuan Basin is the most,which will be 12.3 days every ten years,the Tibetan Plateau and Western Sichuan Plateau are the least,which will be 3.7 to 3.8 days but be not stable.There is the transition of climatic change in five regions of China,but there is no sudden climatic change of rainy days in this period.