Analysis And Prediction Of Drought/flood Variations During Each Period Of Past,Now And Future Over The East China

In this paper, the temporal and spatial variation of dryness and wetness over the east China was studied. By the analysis of each stage, the fact of historical dryness and wetness variation was examined, the characteristic analysis during the recent 40 years and the drought/flood prediction of the 21 century was also done.On the basis of the interpolation method which was widely used in climatology, the latitude-longitude grid dataset of drought/flood grades over the east China in the past 481 years (1470-1960a) are established, and the feasibility of the interpolation method was analyzed to verify that: during the interpolation process of the small number of stations in the past, there isn't any departure of large-scale temporal and spatial variation from the station research, so the interpolation is feasible . Then, using the grid dataset, the distribution characteristic of dryness or wetness was analyzed, additionally, by definition of dryness and wetness area index, the phasic and periodic characteristic of dryness and wetness area changes were studied.For the research of the recent 40 years, first, the varying characteristic of dryness and wetness distribution patterns and dryness and wetness area over the east China have been analyzed by the historical data of the drought/flood grades, and have been compared with the dryness and wetness distribution patterns and dryness and wetness area during the past 481years(1470-1960a) .Then, by using the observational data from 1951-2000, the long-term change trend index of precipitation is calculated, the results show us the general characteristic and regional characteristic of precipitation change trend over the east China.During the 21 century, by using our global ocean-atmosphere coupled model, reference of the IPCC future emission scene of the greenhouse gases and aerosol , and synthesis of several IPCC model simulation results, the precipitation of the future 100 years over the east China was predicted.In addition, for historical drought/flood, this study attempted to combine different types of proxy data (the historical dryness and wetness grades,tree-ring chronology over Huashan,the reconstruction data of precipitation based on the snow and rainfall archives in the Qing Dynasty)to give a more reliable estimate of the historical climate.