中文摘要：

利用1951-2001年江淮地区109个台站的逐日最高、最低气温资料,对江淮地区气温日较差变化趋势的气候特征及其环流背景进行了分析。结果表明,江淮地区梅雨期的气温日较差可划分为南、北、西3个气候区域,各个区域的气温日较差呈现出明显或不明显的减小趋势,北区的减小趋势最为明显;江淮特别是江淮南区气温日较差的异常与江淮地区梅雨期的降水有较好的对应关系;以江淮南区梅雨期气温日较差为代表分析其异常与环流背景的相关关系,发现季风环流、南亚高压加强（减弱）,副高减弱（增强）,低层暖（冷）平流加强,空气柱厚度增加（减小）,使江淮南区降水减少（增多）,利于气温日较差偏大（偏小）。

英文摘要：

On the basis of the daily maximum and minimum temperature data from 109 stations of Jianghuai Area from 1951 to 2001,the climate characteristics and the circulation background of the daily temperature range change trend in Jianghuai Area were analyzed.The results showed that the daily temperature range in Jianghuai Area in Meiyu period could be divided into southern,northern and western climatic areas.The daily temperature range in each region showed obvious or unconspicuous decreasing trends.The decreasing trend in northern area was most obvious.The daily temperature range anomalies in Jianghuai Area had better corresponding relationship with the rainfall in Jianghuai Area in Meiyu period,especially in Jianghuai southern area.Taking the daily temperature range in Jianghuai southern area in Meiyu period for an example,the correlation between the daily range anomalies and the circulation background was analyzed.It was found that monsoon circulation and South Asia high strengthened（weakened）,the subtropical high bated（reinforced）,warm（cool） advection in low level intensified,air column thickness increased（reduced）,which decreased（increased） the rainfall in Jianghuai south area and increased（decreased） the temperature daily range.