The Characteristic Of Climate Change And Influence Factors On It During The Recent 47 Years In The Yangtze River Delta

In this paper,climatic changes of precipitation and air temperature,factors affecting summer rain fall and characteristics of high temperature hazards in the Yangtze River Delta were studied based on climate date including precipitation and air temperature from 59 observational stations in the Yangtze River Delta between 1961 and 2007,5°×10°500hPa height and 5 parameters of subtropical high provided by China Meteorological Center.Tendency analysis,vector EOF expansion,correlation analysis were carried out in this study.The researched results are as follows:(1) The annual precipitation in the Yangtze River Delta had a significant increase,which in summer and winter increased while in spring and autumn reduced,there were lots of precipitation since 1990s,and the increasing trend in the central and southern regions was more significant;In addition to the in line more (less) or the north-south contrast types in summer,the remaining three seasons are in line more(less) distributed.(2) The average temperature in the Yangtze River Delta was increasing,especially in spring,winter and the whole year.the warming area had a zonal distribution along the city center.Since 1990s,the annual,spring, summer and autumn's warming trend was significant,slightly in advance in winter.(3) By analysing the characteristics of the 500hPa height,the subtropical over West Pacific and ENSO,the cause of precipitation anomalies could possible be explored.(4)The increasing trend of extreme precipitation was significant in the eastern part such as Shanghai region, and the increasing of the average annual precipitation in the Yangtze River Delta was showed by the decreace of the light rain(0.1-10mm) days,the apprearant increace of the light rain(10-25mm) days,and the increase of the heavy rain(25-50mm or more than 50mm) days.(5) The warming in the Yangtze River Delta,mainly reflected by the increase of the extreme low temperature and the reduction of the low-temperature days,and the extreme high temperature events showed a significant increase in frequency in the Yangtze River Delta region.The extreme warming areas still had a zonal distribution along the city center,it was evident that the urbanization had effects on the climate change in this region.