天气尺度波列对长江中下游6月梅雨的影响

采用1979—2007年6月NCEP/NCAR2.5°×2.5°逐日再分析资料和中国743站逐日降水资料,利用相关分析、合成分析等方法,分析了天气尺度波列的特征及其对长江中下游6月梅雨的影响。结果表明:当长江中下游6月梅雨较少时,东亚及西太平洋区域存在一个天气尺度波列;该波列的延伸距离较短(从黄河河套地区经过长江中下游至南海、菲律宾海一带),维持时间也很短,且仅仅在500 h Pa以下较强。诊断及个例分析表明,当该波列异常显著时,长江中下游梅雨降水明显减少,而其南部区域降水则增多,说明该波列对预报长江中下游降水具有重要的指示意义。

Impact of synoptic scale wave train on Meiyu over the middle and lower reaches of the Yangtze River in June

Based on the NCEP/NCAR daily reanalysis datasets(2.5°×2.5°) and the daily precipitation datasets of 743 meteorological stations in China in June during 1979-2007,the characteristics of the synoptic scale wave train and its impact on Meiyu in the middle and lower reaches of the Yangtze River are investigated by the correlation analysis method,the synthetic analysis method,etc.Results indicate that,when the precipitation is less in the middle and lower reaches of the Yangtze River in June,there is a synoptic scale wave train over East Asia and West Pacific.The wave train has both shorter duration and extended distance(from Hetao area of the Yellow River to the middle and lower reaches of the Yangtze River,to South China Sea,and to the Philippine Sea),and is stronger only below 500 hPa.Diagnosis and case analyses show that,when the wave train is especially notable,the Meiyu rainfall obviously decreases in the middle and lower reaches of the Yangze River and increases in the south region.It shows that the wave train has an important indicative significance for the precipitation prediction in the middle and lower reaches of the Yangtze River.