西南雨季降水不同年代水汽输送对比分析

Comparison Analysis of Water Vapor Transport in Different Decades during the Rainy Season in Southwest China

摘要: 为了研究西南地区雨季降水不同年代水汽输送的对比，选取了云南和四川的全部地区，以及贵州和重庆的部分地区共81个气象台站资料，从1960年伊始，到2022年的每年雨季的观测资料，还采用了ERA5从1940年至今的压力水平和单一水平的月平均数据，数据的分辨率是0.25˚ × 0.25˚。凭借天气学诊断分析、multiquadric插值算法、相关系数的显著性检验等方法，对西南地区的雨季不同年代水输送进行了详尽的对比分析，其研究结论表明：1) 西南地区整体水汽输送与全球气候变化紧密相关，水汽输送的基本形势是地形上西北方位弱，正东和正南方位强。拥有的若干传统高值区在近30年来均呈减弱趋势，其中云贵交界减弱最为明显，而传统低值区的水汽输送趋势与整体保持一致。2) 对于传统的高值区，水汽输送情况并不一致。对于传统高值区，近30年来减弱程度从高到低分别为云贵交界，雅安周边，云南南部，雅安周边和以及云南南部还将维持稳定的高值降水。3) 存在一个异常带，约位于104˚E附近，这些区域常与西南地区整体呈相反趋势，拥有独立的水汽输送通道，是异常水汽输送的高发区。异常带有向周围扩散的趋势，表现为沿104˚E线向外扩散，这一异常带更多受到来自孟湾向北方向的水汽输送，并引导产生异常降水，伴随西南整体周期性的水汽输送增强和异常降水增多，104˚E周边地区将易发异常低值。

Abstract: To study the contrast of water transport during the rainy season across different decades in Southwest China, data from 81 meteorological stations in Yunnan and Sichuan provinces, as well as parts of Guizhou and Chongqing, were selected. The observation data span from the rainy seasons of 1960 to 2022, and ERA5 monthly average data from pressure levels and single levels, with a resolution of 0.25˚ × 0.25˚, were used from 1940 to the present. Using synoptic diagnostic analysis, multiquadric interpolation algorithm, and significance tests of correlation coefficients, a detailed comparative analysis of water transport during the rainy seasons in different decades in Southwest China was conducted. The study concluded that: 1) The overall moisture transport in Southwest China is closely related to global climate change, with a basic pattern of weak transport in the northwest and strong transport in the east and south directions due to topography. Traditional high-value areas have shown a weakening trend in the past 30 years, with the Yunnan-Guizhou border weakening the most significantly, while the trend in traditional low-value areas remains consistent with the overall pattern. 2) For traditional high-value areas, the moisture transport situation is not uniform. In the past 30 years, the degree of weakening from highest to lowest is as follows: Yunnan-Guizhou border, around Ya’an, and southern Yunnan. Both around Ya’an and southern Yunnan will maintain stable high-value precipitation. 3) There is an anomalous belt approximately located near 104˚E, where these regions often show a trend opposite to the overall trend in Southwest China, having independent moisture transport channels and being high-incidence areas of anomalous moisture transport. This anomalous belt shows a tendency to spread outward along the 104˚E line, more influenced by moisture transport from the north of the Bay of Bengal, leading to anomalous precipitation. Accompanied by the periodic enhancement of moisture transport and increased anomalous precipitation in Southwest China, the areas around 104˚E are prone to anomalously low values.