西南雨季不同年代降水特征对比分析

Comparative Analysis of Precipitation Characteristics of Different Ages in the Southwestern Rainy Season

为了更好地对西南雨季降水的时空变化特征进行研究,利用中国西南地区1960~2022年81个气象站点共63年的逐日降水量气象观测资料,通过经验正交函数分解(EOF)、线性趋势倾向分析和Morlet小波分析等研究方法,揭示西南地区降水的时空分布特征、长期变化趋势以及周期变化特征。分析结果表明:(1) 西南地区1960~2022年的雨季降水量总体呈现下降趋势,其年代际变率为−12.516/10a,降水距平值呈现下降趋势,且降水存在周期性变化。(2) 西南雨季降水量的EOF分析表明:第1模态表明西南地区降水呈全区一致型分布;第2模态呈现南北反位相的分布类型;第3模态降水为由南向北呈现“正–负–正”的分布类型;第4模态降水呈现西北–东南反向的分布类型。(3) 除川西高原地区外,年代降水距平值呈先增后减的趋势,其他区域的年代降水距平值无明显变化规律。西南地区雨季的年代降水距平百分率属于正常变化。In order to better study the spatio-temporal variation characteristics of rainy season precipitation in Southwest China, the day-by-day precipitation meteorological observations from 81 meteorological stations in Southwest China for a total of 63 years from 1960 to 2022 are utilized to reveal the spatio-temporal distribution characteristics of precipitation in Southwest China, the long-term trend by means of the empirical orthogonal function decomposition (EOF), the linear trend tendency analysis and the Morlet wavelet analysis, and the cyclic variation characteristics and cycle change characteristics. The analysis results show that: (1) The rainy season precipitation in Southwest China from 1960 to 2022 shows an overall decreasing trend, and its interdecadal variability is −12.516/10a, the precipitation distance level shows a decreasing trend, and there are cyclic changes in precipitation. (2) The EOF analysis of the rainy season precipitation in Southwest China shows that: mode 1 indicates that the precipitation in Southwest China is uniformly distributed throughout the region;mode 2 shows a north-south antipodal distribution;mode 3 shows a “positive-negative-positive” distribution from the south to the north;and mode 4 shows a northwesterly-southeasterly inverse distribution. (3) Except for the Western Sichuan Plateau area, the distance level of the chronological precipitation shows a tendency of increasing and then decreasing, and there is no obvious pattern of change in the distance level of the chronological precipitation in other areas. The percentage of chronological precipitation distance level in the rainy season in the southwestern region belongs to the normal change.