对流层上层斜压波包活动与2003年江淮流域梅雨的关系

利用NCEP/NCAR再分析和中国740站逐日降水资料, 研究了2003年淮河流域梅雨期间对流层上层斜压波动的传播情况。结果发现, 斜压波组织成波包向下游传播且具有明显的下游频散效应。波动起源于巴尔喀什湖西北侧, 沿着西北－东南向的路径向东南传播, 传至江淮流域大约需要3天。斜压波包所带来的扰动能量为江淮流域暴雨的发生发展提供了必要的能量积聚。通过与1998和1997年这两个梅雨年份的比较, 发现1998年异常强梅雨年的斜压波包的活动特征与2003年的相似, 但在梅雨降水非常偏少的1997年, 未发现有明显的斜压波包向下游的传播。

Activities of baroclinic wave packets in the upper troposphere related to Meiyu of 2003 in the Yangtze River\|Huaihe River valley

Using NCEP/NCAR reanalysis daily data from 1980 to 2003 along with 740-station precipitation data in China,the authors analyze the propagation features of the baroclinic wave packets in middle latitudes of the Northern Hemisphere during the Meiyu period of 2003.The results demonstrate that the baroclinic waves in the upper troposphere organize into the Rossby wave packets during the Meiyu period of 2003,dispersing to their downstream area distinctly.The waves originate from the regions northwest of Lake Balkhash and then spread southeastward to their downstream regions.About 3 days later,wave packets arrive in the Yangtze River-Huaihe River valley.The energy dispersion associated with baroclinic wave packets leads to the energy accumulation for rainstorms in the Yangtze River-Huaihe River valley.To further understand the downstream effect of the baroclinic wave packets,the authors compare the propagation features of the wave packets during the Meiyu periods of 1998 and 1997.It is found that the activities of baroclinic wave packets in flood Meiyu year 1998 are very similar to those in 2003.However,the downstream effect was not clearly observed in 1997 which is known as a dry Meiyu year in the Yangtze River-Huaihe River valley.