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概述了引起1998年长江大洪水的雨情。从天气气候角度分析了1998年长江流域降水异常偏多的原因。指出最直接的原因是副高移动的反常,特别7月15日以后副高突然南撤导致“二度梅雨”天气出现是主要原因之一。对其它诸多大气环流因子和海温异常,如1998年南海季风爆发晚、南亚和东亚季风强度偏弱、夏季赤道辐合带偏弱、热带地区台风生成少、生成时间晚、登陆台风少、亚洲地区上空长期出现阻塞高压、1997年12月至1998年2月青藏高原降雪异常偏多、1997～1998年东太平洋赤道附近发生了本世纪以来最强的一次厄尔尼诺现象等也进行了分析。
Outlines the rains that caused the 1998 floods in the Yangtze River. From the perspective of weather and climate, this paper analyzes the reasons for the abnormally high precipitation in the Yangtze River Basin in 1998. It is pointed out that the most direct reason is the abnormal movement of the subtropical high. In particular, the sudden appearance of the south subtropical high after July 15 resulted in the occurrence of the weather of the second rainy season. For many other atmospheric circulation factors and SST anomalies, such as the late onset of the South China Sea monsoon in 1998, the weak monsoon intensities in South and East Asia, the weak convergence of summer equatorial convergence zone, the low typhoon generation in the tropics, the late generation of landfalls and the low typhoon landed in Asia High-pressure blocking occurred over the region over a long period of time. From December 1997 to February 1998, snowfall over the Qinghai-Tibet Plateau was abnormally high. The strongest El Niño phenomenon since the middle of the equatorial Pacific in 1997-1998 was also analyzed.