长江流域径流量变化过程及其对ENSO和PDO的响应

根据宜昌站、汉口站和大通站的径流量数据，运用M-K检验和小波分析等方法，对1900年以来长江流域径流量的趋势和周期变化进行分析，探究径流量变化对厄尔尼诺?南方涛动（ENSO）和太平洋年代际振荡（PDO）的响应。结果表明：1900 年以来长江流域径流量呈显著的减少趋势，并具有2~8 a的年际周期变化和14~17 a的年代际周期变化。流域径流量与ENSO具有相同的2~8 a周期变化，在El Ni?o发生期，径流量较低，在La Ni?a发生期，径流量较高。14~17 a的周期变化与PDO相关，在暖位相期径流量偏少，在冷位相期径流量偏多。PDO影响着ENSO和径流量之间的相关性，在暖位相期，El Ni?o对径流量的影响增强，在冷位相期，La Ni?a对径流量的影响增强。因此，在分析和预测流域径流量长时间尺度上的变化时要综合考虑ENSO和PDO的影响。

Variation Process of Water Discharge and Its Response to ENSO and PDO in the Yangtze River Basin

Based on the annual and month water discharge at Yichang, Hankou and Datong stations, the trend and periodic variations of water discharge in the Yangtze River Basin since 1900 have been examined by methods of the M-K nonparametric test and the wavelet analysis. Furthermore, to explore the potential response of water discharge to El Ni?o Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). Results show that water discharges in the Yangtze River Basin show a significant decreasing trend since 1900, and water discharge has significant periodic variations at the time scales of 2-8 a interannual periodic variation and 14-17 a interdecadal variation. Water discharges and ENSO events have the same 2-8 a significant periodic variation with characteristics of water discharges decrease in the El Ni?o event and increase in the La Ni?a event. Time scale of 14-17 a periodic variation of water discharge may be related to PDO with characteristic of lower water discharge in the warm phase of PDO and higher water discharge in the cool phase of PDO. The PDO could affect the teleconnections between ENSO and water discharge in the Yangtze River Basin, PDO enhances influence of La Ni?a on water discharge in the cool phase and El Ni?o on water discharge in the warm phase. Hence, to analyze and predict variation of water discharge in long time scale, the comprehensive influences of PDO and ENSO should be considered.