历史时期长江中游水灾与厄尔尼诺事件的遥相关

长江中游历来是长江流域水灾最严重的地区，研究历史时期这一地区水灾发生的变化波动并找出其与厄尔尼诺事件的遥相关，将有助于对长江中游水灾发生的预测。对这二个时间序列自1525年以来的数据进行了统计学分析。结果表明，水灾发生的主要周期比厄尔尼诺事件发生的周期要长：后者主要表现为2年和3~4年的振动，而前者的主要周期为2年、8年和40年，其显著性也没有后者明显（但都超过了0.03的置信度）。通过进一步分析历史时期长江中游水灾与厄尔尼诺事件的耦合振动，发现它们之间存在显著的遥相关。结果表明，长江中游水灾对厄尔尼诺现象的响应不仅存在着如许多中国学者相信的短期滞后（如：1年），而且还存在着比较长时间的滞后（最长可达8年）。研究结果同时表明，如果厄尔尼诺事件发生的相距时间愈短，这一时期长江中游水灾响应的滞后时间也愈短，反之亦然。

HISTIROCAL FLOODS IN THE MIDDLE REACHES OF THE YANGTZE RIVER AND EI Ni(N~)O EVENTS

The basins of middle reaches of the Yangtze River are the worst flood area of whole basin. To study the variation regulation of the floods in this area and EI Nio events over a long historical period and to identify the teleconnection between them assure improvement in predictions of floods in the region. By using statistics analysis, both time series of the floods and EI Nio events since 1525 are studied. The results show that the main cycle of flood variation is longer than that of EI Nio events. The latter obviously shows the fluctuations of about 2-year and 3~4 year period while the former is not so significant but can also be identified obviously the period of 2, 8 and 40 years (at least exceeding the level of confidence {0.03}). By further analyzing the coupling fluctuation of the two time series, the significant teleconnections between them at both high and moderate frequency sections are found. The result turns out that the response of the floods along the middle reaches of the Yangtze River to the effects of El Nio events is not only immediately delay (see one year) as many Chinese scientists believe, but also can be somewhat long-lived (as long as about 8 years). The results also explicate that the shorter the interval of EI Nio events, the sooner the following flood responds. Vice versa, flood could delay if the interval time of EI Nio events is longer.