Analysis Of The Change In The Distribution Of Different Precipitation Intensity Over China Under Global Warming

As an important part of the climate resources, the variation of water resources received significant attention under global warming. Daily precipitation data from364stations during1961-2006are used to analyze and compare the distribution characteristic of different precipitation intensity over of5regions of China under global warming. We use a variable-grid atmospheric general circulation model, LMDZ/IPSL, to compare the distribution of the precipitation intensity over Yangze-Huaihe Basin between current and future. By using Gamma function to fit the distribution of daily precipitation, the changes of shape parameter Alpha and scale parameter Beta of Gamma function are discussed under different climatic background. The result shows that:(1)The average precipitation intensity spectrum tends to ’rich get richer, poor get poorer’in Northwest China and Northeast China, North China, Yangze-Huaihe Basin and South China under global warming. The contribution of light precipitation to total precipitation reduced and the extreme precipitation increased. The change of Yangze-Huaihe Basin is the most significant region. The proportion of heavy rain days in total precipitation days over Yangze-Huaihe Basin in5warmest years chosen by global temperature is30%more than that in5coldest years. But light rain reflects the opposite characteristics, the proportion in warm years is nearly60%less than in cold years.It is the same in the proportion of heavy rain and light rain in total precipitation amounts, the relative difference is about13%and80%, respectively. This change of Yangze-Huaihe Basin has basically been confirmed by the Simulation results of LMDZ.(2)There are some differences in the response of the average precipitation intensity spectrum to global warming over different regions. The change of light precipitation over Yangze-Huaihe Basin and South China is larger than40%, compare with that less than30%over Northwest China and North China; the change of extreme precipitation over Yangze-Huaihe Basin and South China is larger than25%, which is also larger than that in Northwest China and North China, less than20%. The amplitude of change in winter is basically greater than the summer. The contribution of light precipitation in North China decreases,but the contribution of extreme precipitation is almost unchanged, especially in summer, it even reduced. The reason could be the climate tends to drought over North China.(3)The change of the average precipitation intensity spectrum is actually the change of precipitation probability distribution in the statistical theory. The distributions of precipitation intensity over Northwest China and Northeast China, North China, Yangze-Huaihe Basin and South China can be fitted well with Gamma distribution by K-S test. Both Shape parameter ALPHA and Scale parameter BETA of GAMMA distribution of daily precipitation in almost all regions of China has a increasing trend, but there are some regional and seasonal differences. It means that the Probability Distribution Function is negative skewed, the dispersion of PDF increases, which would increase average daily rainfall intensity and increase the probability of occurrence of extreme precipitation. But there are some difference in the changes of Alpha and Beta in different season and regions under global warming.