中文摘要：

为了进一步检验青藏高原、北方冷空气及西太副高对1998年和1991年江南北部和江淮洪涝的影响，利用NCEP／NCAR的再分析格点资料和MM5中尺度模式分别对该两年夏季的两段强暴雨个例作了对照和滤波试验。模拟结果表明：在两次强暴雨个例中，考虑了中高纬度环流、青藏高原热力作用和低纬西太副高影响的对照试验，能相当好地再现中高纬度环流的平均场特征及形势演变的情景；而不包括上述准静止波异常影响的滤波试验的模拟结果与对照试验的结果相差较大，更接近多年平均的7月气候场。这证实北方冷空气活动、高原热力作用和西太副高位置对该两个个例中雨带的重要影响。同时，本文模拟也显示中尺度模式MM5有相当强的模拟中高纬度形势演变的能力，这种保留或滤除准静止波异常的模拟方法不失为一种讨论大尺度准静止波异常对区域气候影响的有效方法。

英文摘要：

Our earlier investigations show the flooding over Changjiang-Huai River（CHR） in summer of 1998 and 1991 related to the fact that there were more southwest vortexes and long-stayed Meiyu front there, the so-called the transient waves inside the region in the following, and the fact that there were stronger cold air north, stronger Plateau thermal effects west and weaker and far south Subtropical High over West Pacific （SHWP）, which is viewed as the external forcing of Quasi-Stationary Waves （QSW） on the large scale outside the CHR. To further verify and exhibit the influences of external forcing of QSW on the flooding both in 1998 and 1991, four about 20 day-long-integral simulations with and without the above external forcing of QSW, i. e. , the control and filtered runs respectively, have been run, utilizing the wide-used NCAR MMSV3 model and the NCEP reanalysis gridded data for both the flood cases of July 15-August 5, 1998 and July 2-16, 1991. Their simulated results averaged over both the whole case processes and each scenario of every 5 days were analysed. Their intercomparisons among the control and filtered runs and the observed illustrated ： （1） Both the control runs with the QSW forcing can quite well reproduce the observed circulation situation in mid- and high-latitudes, and partly reproduce the observed behaviors of the SHWP and main rain belt; while both the filtered ones, in which the QSW anomalies were removed, produce the circulation and precipitation closer to the normal climate values. Namely, the external QSW anomalies, like the cold air north, plateau thermal effect west and the SHWP south, have the significant impacts on the CHR flooding. （2） The PSU/NCAR MMSV3 meso-scale model has the quite good simulative performance in reproducing the circulation in mid- and high-latitudes, especially in the first five days, but the simulated SHWP position and main rainy belt is something north than the observed. Possibly, it relates to the too weak, cold air invading simulat