四川省秋季昼雨的区域变化特征

Regional Variation Characteristics of Autumn Daytime Rain in Sichuan Province

摘要: 为了研究四川省昼雨秋季的区域分布特征，利用四川省126个气象站1961~2021年共61年的逐日降水观测资料，通过经验正交函数分解(Empirical Orthogonal Function Decomposition，以下简称EOF分解)、旋转经验正交函数分解(Rotated Empirical Orthogonal Function Decomposition，以下简称REOF分解)等多种现代气候诊断统计分析方法，较为详细地分析了四川省61年来秋季昼雨的时空分布特征。研究表明：(1) 四川省秋季昼雨空间分布不均匀，秋季昼雨空间分布均表现为东多西少、南多北少的型态，其中大值中心位于东北部，中心达到425 m。秋季昼雨日数最大值在雅安、天全、峨眉一带，中心值达到50 d；秋季昼雨强度大值分布位于川东部，大致中心达到0.3 mm/h。(2) 秋季昼雨的REOF分解结果表明：可分为川南、川东北、川西北、盆地中部和川西高原5个区域。(3) 时间变化上，秋季昼雨趋势线在20世纪80年代从高于均值变成低于均值呈下降趋势，表明昼雨线性减少；秋季的昼雨日数趋势线在20世纪90年代从高于均值变成低于均值呈下降趋势，表明昼雨日数线性减少；秋季的昼雨强度趋势线在20世纪90年代从低于均值变成高于均值呈上升趋势，表明昼雨强度线性增强。南山地5个区域。

Abstract: In order to study the regional distribution characteristics of daytime rainfall in autumn in Sichuan Province, data from 126 meteorological stations across Sichuan Province over a period of 61 years (1961~2021) were utilized. Using modern climate diagnostic statistical methods, including empirical orthogonal function decomposition (EOF decomposition), rotated empirical orthogonal function decomposition (REOF decomposition), and Mann-Kendall abrupt change test, a detailed analysis was conducted on the spatiotemporal distribution characteristics of autumn daytime rainfall in Sichuan Province over the past 61 years. The study found that: (1) The spatial distribution of autumn daytime rainfall in Sichuan Province is uneven, generally showing more rainfall in the east and west, and more in the south and north. The highest concentration of rainfall is in the northeastern part of the province, with a maximum of 425 m. The highest number of autumn daytime rainfall days is observed in the Ya’an, Tianquan, and Emei areas, with a central value of 50 d. The highest intensity of autumn daytime rainfall is located in eastern Sichuan, with a central value of approximately 0.3 mm/h. (2) The REOF decomposition results indicate that the autumn daytime rainfall can be divided into five regions: southern Sichuan, northeastern Sichuan, northwestern Sichuan, central basin, and western plateau. (3) In terms of temporal changes, the trend line for daytime rainfall in autumn shifted from above to below the mean in the 1980s, indicating a linear decrease. The trend line for the number of days with daytime rainfall in autumn also shifted from above to below the mean in the 1990s, indicating a linear decrease. However, the trend line for the intensity of daytime rainfall in autumn changed from below to above the mean in the 1990s, indicating an increase.