基于EEMD的西南雨季降水的多尺度变化特征

Multiscale Variation Characteristics of Rainy Season Precipitation in Southwest China Based on EEMD

利用1960~2022年西南地区81个气象站点共63年的逐日气象降水量观测资料,运用旋转经验正交函数分解(REOF)、Morlet小波分析和集合经验模态分析(EEMD)等方法,对西南地区63年雨季降水量的多尺度变化特征进行了详细研究。结果表明:根据REOF分析表明:第1模态高值区主要在云南地区,低值在川西高原及四川东部;第2模态高值区主要在云南东南部和四川东部,低值区在川西高原;第3模态高值区主要在四川中部及北部,第4模态高值区主要在贵州地区,第5模态高值区主要在四川东部。根据高荷载量以及各种因素可以把西南地区分为5个区域,分别为云南区、川西高原区、川东区、川中区以及贵州区。小波分析表明云南区主要存在准3a、准8a、准23a的降水周期;EEMD分解表明云南区主要有3.2年、6.4年、9.6年、21.3年的周期。小波分析表明川东地区主要存在准7a、准13a、准22a的降水周期;EEMD分解表明川东区主要有3.36年、8年、26.6年的周期。小波分析表明川西高原区主要存在准4a、准8a、准15a、准18a的降水周期;EEMD分解表明川西高原区具有3年、6.4年、8.6年、21.3年的周期。小波分析表明川中区主要有准4a、准6a、准10a、准16a、准27a的降水周期;EEMD分解表明川中区主要有2.78年、7.6年、16年的周期。小波分析表明贵州区主要有准7a、准11a、准15a和准20a的降水周期变化;EEMD分解表明贵州区具有4.15年、10年、20年的周期。由此可知,西南地区主要存在4年、8年和20年左右的周期。Utilizing day-by-day meteorological precipitation observations from 81 meteorological stations in Southwest China for a total of 63 years from 1960 to 2022, the multi-scale variation characteristics of precipitation during the 63-year rainy season in Southwest China were studied in detail by means of Rotation Empirical Orthogonal Function decomposition (REOF), Morlet wavelet analysis and Ensemble Empirical Mode Decomposition analysis (EEMD). The results show that: According to the REOF analysis, the high value of mode 1 is mainly in Yunnan, and the low value is in western Sichuan Plateau and eastern Sichuan. The high value area of mode 2 is mainly in southeast Yunnan and eastern Sichuan, and the low value area is in western Sichuan Plateau. The third mode high value area is mainly in the central and northern part of Sichuan, the fourth mode high value area is mainly in Guizhou, and the fifth mode high value area is mainly in the eastern part of Sichuan. According to the high load capacity and various factors, the southwest region can be divided into five regions, namely Yunnan region, western Sichuan Plateau region, eastern Sichuan region, central Sichuan region and Guizhou region. Wavelet analysis shows that there are mainly quasi-3a, quasi-8a and quasi-23a precipitation cycles in Yunnan. The EEMD decomposition shows that there are 3.2, 6.4, 9.6 and 21.3 years in Yunnan region. Wavelet analysis shows that there are quasi-7a, quasi-13a and quasi-22a precipitation cycles in eastern Sichuan. The EEMD decomposition shows that there are 3.36 years, 8 years and 26.6 years in eastern Sichuan. Wavelet analysis shows that the precipitation periods of quasi-4a, quasi-8a, quasi-15a and quasi-18a mainly exist in the western Sichuan Plateau. The EEMD decomposition shows that the western Sichuan Plateau has a period of 3 years, 6.4 years, 8.6 years and 21.3 years. Wavelet analysis shows that the main precipitation periods in central Sichuan are quasi-4a, quasi-6a, quasi-10a, quasi-16a and quasi-27a. The EEMD decomposition shows that there are 2.78 years, 7.6 years and 16 years in central Sichuan region. The wavelet analysis shows that there are mainly quasi-7a, quasi-11a, quasi-15a and quasi-20a precipitation cycles in Guizhou. The EEMD decomposition shows that the Guizhou region has 4.15-year, 10-year and 20-year cycles. It can be seen that there are cycles of about 4 years, 8 years and 20 years in southwest China.