黄河源区径流量的季节变化及其与区域气候的小波相关

Seasonal Variations of Runoff and Its Wavelet Correlations with Regional Climate in Source Region of the Yellow River

采用交叉小波分析方法，分析了黄河源区达日站四季径流量与区域降水量、蒸发量以及最高、最低气温之间的时频域统计特征，讨论了黄河源区河川径流的季节变化及其与气候要素之间的多时间尺度相关。结果表明，黄河源区径流量具有明显的年际和年代际变化，存在着2～4a、6～8a和12～22a尺度的显著变化周期。夏秋季径流变化与区域降水量之间年际和年代际尺度正相关振荡的凝聚性最强，秋季两者相关程度更高；夏季径流与区域蒸发量、最高和最低气温的年代际尺度相关凝聚性高于秋季，径流变化对区域蒸发和气温异常的响应时间也不相同。冬春季径流变化与最高、最低气温的高凝聚性相关表现在年际尺度共振周期上，春季径流与最高气温的负相关程度高于冬季，冬季径流与最低气温的正相关高于春季。分析认为，区域降水量是黄河源区丰水期径流变化的主导因子，最高、最低气温对枯水期径流变化具有重要影响；不同季节气候要素对河川径流的影响机制不同，径流变化对区域气候异常的响应时间存在差异，黄河源区径流变化是气候要素综合作用的结果。

The cross wavelet transform method is adopted to analyze the runoff characteristics in time and frequency domains and the multi-time scale correlations between the runoff and regional precipitation, evaporation, maximum temperature and minimum temperature in source region of the Yellow River. The results show that runoff in source region of the Yellow River have interannual and interdecadal periodic variations and there are significant periods at scale of 2-4 a, 6-8 a and 12-22 a. In summer and autumn, the coherence of positive correlation oscillations at interannual and interdecadal scale between the runoff and regional precipitation is the highest and the correlation degree in autumn is higher than in summer. The coherences of interdecadal correlation oscillations in summer between runoff and regional evaporation, maximum and minimum temperature are higher than in autumn, and the phase differences of them show that responding times of the runoff variations to the regional evaporation and temperature anomalies are also different. In winter and spring, the high coherence of correlative oscillations between the runoff and maximum and minimum temperature exhibit on syntony periods at interannual scales. Negative correlation between the runoff and maximum temperature in spring is higher than in winter, and positive correlation between the runoff and minimum temperature in winter is higher than in spring. The primary factor of the runoff variations in flood season in source region of the Yellow River is the regional precipitation, while the maximum temperature and the minimum temperature have important influence on the runoff variations in low-water seasons. Mechanism of climatic elements influencing the runoff variation in different seasons is different, and responses of the runoff variation to regional climate anomalies are different. The runoff variations in source region of the Yellow River are resulted from the conjunct influence of climatic elements.