中国华东地区夏季高温的时空特征和年际变化

Temporal-Spatial Characters and Interannual Variations of Summer High Temperature in East China

利用中国华东地区1961-2004年夏季（7-8月）气温观测资料，分析了该区域夏季气温的总体变化特征，指出华东地区夏季气温具有降低的长期趋势。定义3项判别标准，得出该区域44a来有10个异常高温夏季。旋转经验正交函数（REOF）展开表明，华东地区夏季平均气温场可分为3个区域：北区气温在21世纪初有明显上升，中区和南区气温无显著突变；各区域气温以2a、3～4a的周期振荡为主；20世纪90年代以来，异常高温年出现频繁。

The observational temperature data （July--August, JA）from 1961 to 2004 in East China have been used to analyze the interannual variations of regional summer temperature anomalies related to the hot summer events in the present article, and the descending trend of the summer temperature has been found. Three criterions for defining hot summers have been set up,and 10 hot summers in the recent 44 years have been indentified. The JA mean temperature field in East China can be divided into three subdivisions with the rotated empirical orthogonal function （REOF） method. The analyses of the climatic catastrophic features as well as periodicities for each subdivision show that there are no significant temperature changes in these subdivisions except the northern subdivision where summer temperature has obviously increased in the 21 st century. The periods of both 2 yrs and 3--4 yrs are found to dominate in any one of the three subdivisions.