三峡库区降水特征及其与大气环流因子的潜在联系

Characteristics of Precipitation in the Three Gorges Reservoir Area and Its Potential Relationship with Atmospheric Circulation Factors

探究三峡库区降水时空特征及其对气候变化的响应,对大型库区影响下的区域水资源安全与防洪抗旱具有重要意义。基于18个气象站点1959年1月1日—2019年12月31日的逐日降水数据,分析了三峡库区年尺度和4个季节尺度下的降水时空变化特征,计算了降水集中度,并通过小波相干分析方法,分析了降水集中度与大气环流因子间的潜在关系。结果表明:(1)时间分布上,三峡库区蓄水前的年际、夏季和冬季降水量变化均呈不显著的上升趋势,春季和秋季的均呈不显著下降趋势,且秋季的下降趋势更明显;蓄水后,年际、春季和秋季降水量变化均呈不显著的上升趋势,夏季和冬季的均呈不显著下降趋势。(2)空间分布上,年降水量与各季降水量的空间分布特征从库首至库尾均呈现“低—高—低”的变化趋势。(3)三峡库区蓄水前的降水集中度呈不显著上升趋势,蓄水后的降水集中度呈不显著下降趋势;蓄水后的降水集中度均值较蓄水前的有所增加。(4)降水集中度与大气环流因子间存在共振周期,不同时域中的相关性不同。

Exploring the temporal and spatial characteristics of precipitation in the Three Gorges Reservoir area and its response to climate change is of great significance for analyzing regional water resources and flood control and drought relief under the influence of large-scale reservoir areas. Based on the daily precipitation data of 18 meteorological stations from January 1, 1959 to December 31, 2019, the temporal and spatial variation characteristics of precipitation in the Three Gorges Reservoir area on an annual scale and four seasonal scales were analyzed, and the precipitation concentration was calculated. The wavelet coherence analysis method is used to analyze the potential relationship between precipitation concentration and atmospheric circulation factors. The results are as follows. Firstly, in terms of time distribution, the interannual, summer and winter precipitation changes in the Three Gorges reservoir area before the impoundment showed an insignificant upward trend, while those in spring and autumn showed an insignificant downward trend, and the downward trend in autumn was more obvious. After impoundment, the interannual, spring, and autumn precipitation showed an insignificant upward trend, while summer and winter showed an insignificant downward trend. Secondly, in terms of spatial distribution, the spatial distribution characteristics of annual precipitation and precipitation in each season showed a trend from low to high and finally low from the head to the tail of the reservoir. Thirdly, precipitation concentration in the Three Gorges Reservoir area showed an insignificant upward trend before water storage, and a non-significant downward trend in precipitation concentration after water storage, and the average precipitation concentration after water storage increased compared with that before water storage. Fourthly, there is a resonance period between precipitation concentration and atmospheric circulation factors, and the correlations are different in different time span.