1998年夏长江流域特大洪涝特征及其成因探讨

利用实际观测资料来分析１９９８年夏发生在长江流域特大洪涝的气候与水文特征，并探讨其成因。分析结果表明，造成１９９８年夏长江流域特大洪涝的成因可能是：在ＥＮＳＯ循环中ＥｌＮｉｎｏ事件由成熟期转变为衰减期时热带太平洋海温，特别是热带西太平洋次表层海温变冷，菲律宾周围对流活动减弱，致使西太平洋副热带高压位置偏南，从而使亚洲夏季风从孟加拉湾、南海携带大量的水汽和热带西太平洋以及西风带来的水汽先在长江中、下游，后在长江中、上游流域辐合，造成长江流域的持续性强降水

The Features of the Catastrophic Flood over the Changjiang River Basin during the Summer of 1998 and Cause Exploration

By use of the observational data, the climatic and hydrological features of the catastrophic flood over the Changjiang River basin during the summer of 1998 are analysed, its cause is also explored. The possible cause is shown as follows, during the transition of El Nio event from the mature stage to decaying stage in ENSO cycle, sea surface temperature in the tropical Pacific particularly sea subsurface temperature in the tropical west Pacific becomes cooler, the convection activities around Philippines decrease, thus the west Pacific subtropical high is located more southward, as a result, an abundant moisture from the Bay of Bengal and South China Sea carried by Asian summer monsoon converges with moisture from the tropical west Pacific and the westlies first in the middle and lower reaches of the Changjiang River and then in the upper and middle reaches, causing continuously severe rainfall in the Changjiang River basin.