西南雨季降水时空变化特征

Temporal and Spatial Variation Characteristics of Rainy Season Precipitation in Southwest China

摘要: 为研究西南雨季降水的时空变化特征，利用1960~2022年西南地区81个气象站点的逐日气象降水量观测资料，通过EOF分解、Morlet小波分析和EEMD分析等方法，对西南地区雨季降水量的多尺度变化特征进行了详细研究。结果表明：1) 西南地区63年来雨季降水量空间分布不均匀，大体有由东向西逐渐递减，以及由南向北逐渐递减的变化趋势。川西高原为降水量低值区，雅安、峨眉以及云南南部为降水量高值区。西南地区趋势系数正值区和负值区交错分布，正值区主要在川西高原以及川东和贵州，负值区在云南地区。2) EOF分析表明：西南地区雨季降水量第1模态为全区一致型，大值中心位于云南地区以及四川中南部。西南地区雨季降水量第2模态显示为北负南正型，正值大值中心位于云南地区，负值大值区位于川西和川东。西南地区雨季降水量第3模态显示为东北到西南正负交错的分布类型。西南地区雨季降水量第4模态为西负东正的分布类型。西南地区雨季降水量第5模态显示为东北到西南呈正负交错的分布类型。3) 小波分析表明西南地区雨季降水量主要有3~4年、7~8年、10~14年、15~23年的变化周期；EEMD分解表明西南地区雨季降水量主要有2.66年、5.33年、10年、21.3年的变化周期。由此可知，西南地区主要存在4年、8年和20年左右的周期。

Abstract: In order to study the spatio-temporal variation of rainy season precipitation in Southwest China, the multi-scale variation of rainy season precipitation in Southwest China was studied in detail by means of EOF decomposition, Morlet wavelet analysis and EEMD analysis, based on the daily meteorological precipitation observation data of 81 meteorological stations in Southwest China during 1960~2022. The results show that: 1) The spatial distribution of rainy season precipitation in Southwest China in the past 63 years is uneven, with a gradual decline from east to west and from south to north. The West Sichuan Plateau has a low precipitation value, while Ya’an, E’mei and southern Yunnan have a high precipitation value. The positive and negative regions of the trend coefficient in Southwest China are interleaved, the positive regions are mainly in the west Sichuan Plateau, the east Sichuan and Guizhou, and the negative regions are in Yunnan. 2) The EOF analysis shows that the first mode of precipitation in the rainy season in southwest China is the uniform type in the whole region, and the large value center is located in Yunnan and central and southern Sichuan. The second mode of rainy season precipitation in Southwest China shows that the north is negative and the south is positive. The positive value center is located in Yunnan, and the negative value area is located in west and east Sichuan. The third mode of precipitation in the rainy season in Southwest China shows the distribution type of positive and negative interleaving from northeast to southwest. The fourth mode of precipitation in the rainy season in Southwest China is the distribution type of west negative and east positive. The fifth mode of precipitation of rainy season in Southwest China shows the distribution type of positive and negative from northeast to southwest. 3) Wavelet analysis shows that the rainy season precipitation in Southwest China mainly has a change cycle of 3~4 years, 7~8 years, 10-14 years and 15~23 years. The EEMD decomposition shows that the rainy season precipitation in Southwest China mainly has a change cycle of 2.66 years, 5.33 years, 10 years and 21.3 years. It can be seen that there are cycles of about 4 years, 8 years and 20 years in Southwest China.