洞庭湖流域气候变化特征(1961-2003年)

Characteristics of climate change in the Lake Dongting Basin (1961-2003)

以22个气象站1961-2003年的气象观测数据为基础,对洞庭湖流域的气温、降水和参照蒸散量进行趋势与突变分析．从1970年开始,洞庭湖流域经历了一个缓慢而稳定的增温过程,1990s发生突变进入快速增温时期；尤其是是在春、冬季节,这种突变式的增温特征非常显著；秋季持续而稳定增温,而夏季气温并无明显变化．进入1990s,洞庭湖流域降水有明显增多,尤其是夏季降水突变式增加；与此同时,夏季暴雨频率也突变式增大,但是暴雨强度并无明显变化．1900s迄今,参照蒸散量持续而稳定的减少,夏季减少量尤为显著．全球变暖的区域响应,驱动洞庭湖流域水循环速度加快,夏季降水增多,而蒸发能力减弱,这是1990s洞庭湖流域洪水频发的主要气候因子．

This paper has detected the trends and abrupt changes of climate changes in Lake Dongting basin in the past 40 years based on observed data of 22 meteorological stations. Lake Dongting basin had undergone a slow but steady increase of temperature since 1970s, but a significant increase with abrupt change has been detected since 1990s, especially in spring and winter; while in summer, the temepreture has changed little. A positive and abrupt trend of precipitation in summer as well as its storm frequency has been well detected in 1990s ; on the contrary, hardly has the storm density changed. The reference evapotranspiration has decreased steadily and obviously since 1960s; and in summer the decrease is of much more significance. The accelerated water circulation driven by global wanning-up has brought the Lake Dongting basin more precipitation in summer, but the reference evapotranspiration has decreased at the same time, as is the main climatic contributor to the frequent floods in summer in 1990s.