热带太平洋海表温度对厄瓜多尔季节性径流变化的影响
Tropical Pacific SST influence on seasonal streamflow variability in Ecuador
AI总结：
本研究利用1979—2015年45个水文站数据，通过趋势分析和奇异值分解，揭示了热带太平洋SST对厄瓜多尔湿季和干季径流的影响，发现典型厄尔尼诺与厄尔尼诺Modoki分别主导不同季节的径流变率，为径流模拟提供依据。
摘要：
本研究对1979—2015年期间厄瓜多尔径流的时空变异性进行了全流域范围的评估。分析了热带太平洋海表温度（SST）对2月至4月（FMA）期间径流变异性的影响，该时段为厄瓜多尔湿季中径流量最大的月份，以及对6月至8月（JJA）干季径流的影响。首先，通过对位于厄瓜多尔不同流域的45个水文站的月径流数据应用Sen斜率估计法和Mann-Kendall检验，进行了长期趋势分析。沿海地区在7月至1月表现出最高的普遍正趋势，而太平洋安第斯地区的结果表明季节性正在增强，除8月、9月和10月呈负趋势外，其余所有月份的径流量总体增加。其次，应用奇异值分解（SVD）来寻找FMA径流与准同期SST（12月至2月，DJF）之间以及JJA径流与同期SST之间的主要耦合变率模态。结果揭示了DJF SST/FMA径流的两个主要耦合模态，第一个与典型厄尔尼诺（canonical El Niño）相关，第二个与厄尔尼诺Modoki（El Niño Modoki）相关。后者对厄瓜多尔大部分地区的FMA径流产生了主要影响。然而，对于JJA径流而言，与传统厄尔尼诺相关的模态更为重要。这些结果为基于太平洋SST的厄瓜多尔径流模拟奠定了基础，表明径流对不同类型厄尔尼诺事件具有强烈响应。
英文摘要：
This study presents a basin wide assessment about the spatio-temporal variability of streamflows in Ecuador for the period 1979-2015. The influence of the tropical Pacific sea surface temperature (SST) on stremaflow variariability from February to April (FMA) period, as the months showing maximum stramflow for the wet season in Ecuador, and from the June to August (JJA), correspondign to the dry season, was analysed. First, a long-term trend analysis was carried out by applying the Sen's slope estimator and the Mann-Kendall test to monthly streamflow data from 45 gaging stations located in different basins across Ecuador. While the coastal region showed the highest generalized positive trends from July to January, the results for the Pacific Andean area suggested a strengthening of the seasonality, presenting an overall increase in the streamflow for all months except August, September and October, which showed negative trends. Second, a singular-value decomposition (SVD) was applied in order to find the main coupled variability patterns between the FMA streamflow and the quasi-coetaneous SST (December-February, DJF) and between the JJA streamflow and the coetaneous SST. The results revealed two main coupled modes for DJF SST/FMA streamflow, the first associated with the canonical El Niño and the second with El Niño Modoki. The latter exerted a major influence on FMA streamflow over most of Ecuador. For JJA streamflow, however, the pattern associated with the traditional El Niño was even more relevant. These results establish the foundations for streamflow modelling in Ecuador based on the Pacific SST, showing the strong response of the streamflows to different types of El Niño events
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