近60年西南地区夏季降水量气候变化特征

Characteristics of Summer Precipitation and Climate Change in Southwest China in Recent 60 Years

摘要: 利用西南地区76个站点1961~2017年共57年逐日降水量资料，运用EOF分解、谐波分析、EEMD分解等方法，详细分析西南地区夏季降水量的时空变化特征，结果表明：1) 西南地区夏季降水量空间分布不均，普遍在500 mm以上，四川盆地和云贵高原南部地区存在降水极值区。EOF分析表明西南地区夏季降水第一模态存在北–东南型及西南–东南型反向空间分布、第二模态存在非对称三极型空间分布、第三模态存在东北–西南型空间分布。2) 西南地区夏季降水量时间演变不均，1972年存在降水极低值，为415.87 mm，1998年存在降水极高值，为661.15 mm，存在明显的年际–年代际变化。EEMD分解表明：在年际尺度上，西南地区降水具有准3a (IMF1)和准5a (IMF2)的显著性周期；在年代际尺度上，具有准12a (IMF3)和准28a (IMF4)的显著性周期，其中年代际振荡12a (IMF3)在西南地区降水长期变化中占据主导地位，且通过显著性检验。

Abstract: Using the daily precipitation data of 76 stations in Southwest China from 1961 to 2017 for 57 years, and using EOF analysis method, harmonic analysis, EEMD decomposition and other methods, the temporal and spatial variation characteristics of summer precipitation in Southwest China were analyzed in detail. The results show that: 1) the summer precipitation in Southwest China is unevenly distributed, generally above 500 mm, and there are extreme precipitation areas in the Sichuan Basin and southern Yunnan and Guizhou. EOF analysis shows that the first mode of summer precipitation in Southwest China has a north-southeast type and southwest-southeast type inverse spatial distribution, the second mode has an asymmetric three-pole spatial distribution, and the third mode has a northeast-southwest type spatial distribution. 2) The temporal evolution of summer precipitation in Southwest China is uneven. In 1972, there was an extremely low precipitation value of 415.87 mm, and in 1998, there was an extremely high precipitation value of 661.15 mm, with obvious interannual-interdecadal variation. The EEMD decomposition shows that: on the interannual scale, the precipitation in Southwest China has significant periods of quasi-3a (IMF1) and quasi-5a (IMF2); among them, the decadal oscillation 12a (IMF3) is dominant in the long-term variation of precipitation in southwest China, and it passes the significance test.