夏季中国东部地区海陆温差变异及其与降水的关系

Land-sea thermal difference variations and its association with summer precipitation in eastern China

利用1957-2010年中国东部（105°E以东）355个站点的温度、降水观测资料和Hadley中心的HadISST海温再分析资料以及EOF等分析方法,分析了中国东部地表气温和邻近海域海表温度的时空变化特征,构建了一个用于表征夏季中国东部与邻近海域纬向海陆热力差异的温差序列,探讨了该序列的变化特征及其与中国东部夏季降水的关系.结果表明：（1）夏季海陆表面温度变化的强信号区分别位于中国黄海、东海北部及邻近海域和长江中下游地区;（2）夏季强信号区的海陆温差序列有明显的年际和年代际变化特征,约为4-6、8和15a的变化周期.此外,在2000年前后7月海陆温差发生明显转折,在1957-2000年期间,海陆温差幅度有下降的趋势,2000年之后则有上升的特点,并且与中国东部降水相关关系也不同;（3）6月份的海陆温差与中国东北大部分地区的降水有明显的正相关关系,7月份则与中国长江中下游及南部地区的降水有显著的负相关关系.这表明夏季中国东部纬向海陆热力差异的变化可能对中国东部的降水有重要的影响.

In this paper, the temporal and spatial characteristics of the land surface temperature anomaly and SST a- nomalies were analyzed based on the observed summer land surface temperature and precipitation datasets from 355 stations in eastern China and HadISST reanalysis data for the period 1957 -2010. An index of land-sea thermal difference was built to represent the characterization of zonal land-sea thermal difference between eastern China's Mainland and its adjacent seas. Then the relationship between the index and summer precipitation in eastern China was discussed. The results show that regions where the land and sea surface temperature changed significantly mainly are located in the lower reaches of the Yangtze River and the yellow sea and East China Sea and their adjacent seas, respectively. It is found that there are significant interannual and interdecadal variations of the land-sea temperature difference, its interdecadal periodicity is about 4 -6 years ,8 years and 15 years interannual periodicity in July. Moreover, the land-sea temperature difference of July declined from 1957 to 2000, and rose after 2000. Besides, the results of the correlation analysis indicate that the index has a significandy negative relationship to summer precipitation in the middle and lower reaches of the Yangtze River in June, and an obvious positive relationship to precipitation in Northeastern China. The results suggest that this local-zonal land-sea thermal difference between eastern China's Mainland and its adjacent seas is very likely to play an important role in the process of summer rainfall in eastern China.