403 / 2024-03-13 16:01:32

Analysis on the influence of typhoons on precipitation in the upper reaches of the Yangtze River during the storage period of the Three Gorges Reservoir

Typhoon,Storage period of the Three Gorges Reservoir,Precipitation in the upper reaches of the Yangtze River,Circulation situation

Subtheme 2: Integrated Water Resources Management > Topic 3: Optimal allocation and effective utilization of Water Resources

The topography of the upper reaches of the Yangtze River is complicated and the climate is changeable. During the storage period of the Three Gorges Reservoir, Typhoon has an indirect effect on precipitation in the upper reaches of Yangtze River under a certain circulation situation. In order to determine the influence of typhoon on precipitation in the upper reaches of Yangtze River, this study analyzes the relationship between typhoons and daily precipitation in the upper reaches of the Yangtze River during the storage period (September and October) of the Three Gorges Reservoir from 1992 to 2021, and finds that the westbound and northwestward typhoons and the typhoons turning in the west of 130°E have a greater impact on precipitation in the upper reaches of the Yangtze River. By atmospheric circulation analysis and diagnostic analysis of cases, it is found that the circulation situation conducive to precipitation in the upper reaches of the Yangtze River for westbound and northwestward typhoons is that there is cold vortex in the middle and high latitudes and cold air is transported to the upper reaches of the Yangtze River. The upper reaches of the Yangtze River is located in the western or northwestern periphery of the subtropical high, and the typhoon moves to the west or northwest along the southern edge of the subtropical high. For turning typhoons, the circulation that is conducive to precipitation is characterized by the input of cold air from the middle and high latitudes. The northwest edge of the subtropical high extends west to the middle of the upper reaches of the Yangtze River, or combines the South Asia High and its northeast edge is located in the lower reaches of the Jinsha River, and the typhoon turns to the northeast within the subtropical high or cuts off the subtropical high to the northeast. The weather situation unfavorable to precipitation in the upper reaches of the Yangtze River is characterized by the subtropical high extending west to the middle area of the upper reaches of the Yangtze River, located in the south of the Yangtze River basin or retreating to the sea.