中文摘要：

通过对1996年和1999年上海强梅雨的分析，发现在强梅雨年的梅雨期内140°E以西的西北太平洋上无热带气旋（以下简称TC）活动，使副高脊线和梅雨锋得以持久稳定，造成长江中下游地区的长时间强（多）梅雨。研究还表明，强梅雨年的副高脊线比常年偏北1-4个纬距，梅雨量的多少与副高、西风带系统的强弱、系统稳定控制的时间长短及其系统相互作用的位置有关。

英文摘要：

Analysis of two strong Meiyu process at Shanghai in 1996 and 1999 shows there is no tropical cyclone in the west of 140 °E in the Northwest Pacific during strong Meiyu process. Steadiness of the ridge of subtropical high and Meiyu front cause strong heavy rainfall for long time in the middle and lower reaches of the Yangtze River. It also shows the ridge of subtropical high in strong Meiyu year is much north than that in average year. Precipitation during Meiyu process is closely related with subtropical high, intensity of systems in westerly, steady time of dominant system, and the reciprocity among systems.