1951—2009年中国地表湿润状况变化趋势研究

利用1951—2009年中国160站的月降水和月平均温度资料,通过计算地表湿润指数,在分析其与降水及气温联系的基础上,探讨了中国区域平均地表湿润指数的年代际变化特征差异,给出了地表湿润指数年趋势的地理分布。结果表明：1951—2009年,中国北方的西北地区东部、华北和东北地区长江中下游地区及东南部分地区以干旱化趋势为主,这些地区干旱化趋势的产生与降水年际变差大、年内分配不均,降水持续减少和气温升高密切相关。东南、西南地区及西藏地区于20世纪90年代初期有湿向干的趋势转换,虽然长江中下游地区在70年代初期有明显的干向湿的趋势变换,但于90年代同样出现湿向干的趋势转换,并一直持续显著的干旱化。

Variation trend of surface humid index in China from 1951 to 2009

Based on the monthly air temperature and precipitation data from 160 observational stations in China from 1951 to 2009,the surface humid index was calculated and its relationships with air temperature and precipitation were analyzed.The inter-decadal characters of the surface humid index were discussed and the geographical distributions of the annual surface humid index were presented.The results indicate that drought is the main characters in the east of northwestern China,north China,northeast China,the middle and lower reaches of the Yangtze River and southeast China.The large difference of inter-annual precipitation,the uneven distributions of yearly rainfall,the persistent decrease of precipitation and warming are the main reasons causing drought in these regions.The climate transforms from wet to dry in the early 1990s in the southeast and southwest China and in the Tibet regions.Although the climate transforms significantly from dry to wet in the early 1970s in the middle and lower reaches of the Yangtze River,it varies from wet to dry in 1990s and remains persistent arid characters.