近40年中国暖季日气温及其异常强度变化趋势

Trends on the Daily Mean Air Temperature and Its Anomalous Strength in China for the Warm Season in the Last 40 Years

利用中国大陆453个测站1961～2000年的逐日平均气温资料,通过标准差和Skewness系数计算日气温距平强度,反映中国近40年来暖季(5-9月)气候变化趋势.近40年中国暖季增温的幅度有南北差异,以黄河流域为界,北边高纬增温更强烈;平均气温趋势有前后两段的显著差别,大致在1970年代后期实现向增温趋势的转变;最强的增温出现在1990年代以后.多数区域气温反映出季节内气候变率增大,显示暖季日平均气温趋于大的涨落.日气温距平和降水有良好的对应关系.由于降水时的气温降幅较大,故暖季中天气过程的降温和持续高温一样是季节内气候变率的重要信号,这在低纬沿海地区(如华南、云南)尤为明显.

Trends on the daily mean air temperature and its anomalous strength in China for the warm season (May-September) in the last 40 years (1961-2000) were analyzed using observational 453-station datasets including daily temperature and daily precipitation. Calculation methods are standard deviation and Skewness. Results show that there were different spatial-temporal characteristics in the daily air temperature variability. In the last 40 years, a warming trend was commonly noted in China but the stronger warming was located in the area north of the Yellow River. For the time evolution, a transition time point was found in the late 1970s from a cooling trend to a warming trend but the stronger warming appeared since the late 1990s. The amplifying daily temperature anomaly indicated a trend of climate variability in many places of China. The relationships between daily air temperature and rainfall events were also discussed particularly in the coastal regions.