中文摘要：

本文基于集中度和集中期的定义方法，利用1960～2007年的48年江淮地区站点的日平均温度资料和累积频率的阈值统计方法，分析梅雨期江淮地区极端高温事件的非均匀分布特征．结果表明，集中度和集中期的方法能够定量地表征梅雨期江淮地区极端高温事件的非均匀分布特征．集中期的异常型为全场一致和南北异常型，集中度的异常分布主要为南北异常和东西异常．进一步比较集中度和集中期异常与同期环流系统的配置关系得知，当集中期南北异常变化时，在高纬度的北太平洋区域出现一对正负的异常模态，且随高度增加而增强，为相当正压结构．海温的异常集中在北太平洋的北美沿岸的显著负异常中心．当集中度为东西异常时，主要环流异常型为约在160°W左右出现“＋-＋-”的200hPa纬向西风异常波列形式从低纬度到高纬度地区传播以及与ENSO的显著负相关．

英文摘要：

Based on the definition of concentration density （CD） and concentration period （CP）, uneven distribution characteristics of warm extremes during Meiyu period over Yangtze-Huaihe region are analyzed by using data of daily averaged temperature from 1960 to 2007 and method of cumulating frequency threshold. Results show that the definition of CD and CP can do a quantitative description of the uneven distribution characteristics. The anomaly pattern of CP is uniformly south-north anomalies, while the pattern of CD is south-north and west-east anomalies. Furthermore, a comparison of configuration between the circulation and CP and CD anomalies shows that when the south north anomaly of CP occurs, a ＂＋ -＋＂anomaly mode appears over north Pacific. In addition, the intensity increases with the altitude, that leads to an equivalent barotropic structure. The sea temperature anomaly is located at the significantly negative center on the coast of North America in the north Pacific. When the west-east anomaly of CD happens, there is an unusual westerly wave at 200 hPa with the pattern of ＂＋- ＋ --＂ around 160°W transferring from low latitude to high latitude. More importantly, the circulation pattern has a significantly negative correlation with ENSO.