四川省夏季夜雨的时间变化特征

Time Variation Characteristics of Summer Night Rain in Sichuan Province

摘要: 为研究四川省夏季夜雨的降水时空变化特征，本文利用四川省1961~2021年共61年全省126个基本气象站的逐日降水观测资料，采用Morlet小波分析和集合经验模态分解(Ensemble Empirical Mode Decomposition，以下简称EEMD分解)，详细探讨了四川省夏季夜雨降水的时间变化特征。结果表明：1) 在REOF结果表明，四川省夏季夜雨可划分为四个区域，即盆地西北型(方差贡献率25.7%)、川东北型(方差贡献率17.3%)、南北相反型(方差贡献率13.6%)和高原盆地相反型(方差贡献率8.5%)。其中，盆地西北型增长速度为−0.067•(10a)⁻¹，川东北型为−0.087•(10a)⁻¹，南北相反型为−0.117•(10a)⁻¹，而高原盆地相反型为0.074•(10a)⁻¹。2) 综合四川省夏季夜雨量REOF各区域的Morlet小波与EEMD分析，可知：盆地西北区域夏季夜雨主要有30年的周期变化和2~3年的短周期变化；川东北区域除2~3年短周期变化外，还有7~9年和30年左右的较长周期变化；盆地南部区域有3~4年和30年左右两个主要变化周期；川西高原区大部分时间段变率小，无稳定的较长时间变化周期，以2~3年短周期变化为主。

Abstract: To study the spatiotemporal variation characteristics of summer night rain precipitation in Sichuan Province, this paper uses daily precipitation observation data from 126 basic meteorological stations in the province from 1961 to 2021. Morlet wavelet analysis, and Ensemble Empirical Mode Decomposition (EEMD decomposition) are used to explore in detail the temporal variation characteristics of summer night rain precipitation in Sichuan Province. The results showed that: 1) In the REOF analysis, summer night rain in Sichuan Province can be divided into four regions, namely the northwest basin type (variance contribution rate 25.7%), the northeast Sichuan type (variance contribution rate 17.3%), the north-south opposite type (variance contribution rate 13.6%), and the plateau basin opposite type (variance contribution rate 8.5%). Among them, the growth rate of the northwest basin type is −0.067•(10a)⁻¹, the northeast Sichuan type is −0.087•(10a)⁻¹, the north-south opposite type is −0.117•(10a)⁻¹, and the plateau basin opposite type is −0.074•(10a)⁻¹. 2) Based on the Morlet wavelet and EEMD analysis of summer night rain in various regions of the REOF in Sichuan Province, it can be concluded that the summer night rain in the northwest region of the basin mainly exhibits a 30-year cycle and a 2~3 year short cycle; In addition to short-term fluctuations of 2~3 years, the Northeast Sichuan region also experiences longer cycles of 7~9 years and around 30 years; The southern region of the basin has two main cycles of change: 3~4 years and around 30 years; Most of the time periods in the western Sichuan Plateau region have low variability and no stable long-term cycles, with a predominance of short cycles of 2~3 years.