Analysis of the Climate Change Tendency and Abrupt Climate Change in Nansihu Basin over 1960-2005

Analyzing the monthly data of air temperature and precipitation,as well as the 20-cm pan-evaporation,in 1960-2005 from 22 meteorological stations over Nansihu basin,the climate change tendency and abrupt climate change in the recent 46 years were revealed.The results show that the mean air temperatures in spring and winter and the annual mean air temperature have increased obviously,while the changes of seasonal and annual precipitations are not marked.The seasonal and annual pan-evaporations have decreased obviously,with changing amplitude in summer and spring higher than that in autumn and winter.The annual mean air temperature had presented an abrupt rising in 1985,the annual precipitation has not presented abrupt change,and the annual pan-evaporation had presented abrupt changes in 1969 and 1985.The observed data of pan-evaporation are not followed with the rising of air temperature;which is not consisted with anticipation.The long-term tendency of pan-evaporation can not be explained by the change of a single environmental factor.